Rosin Ester Handbook - Arizona Chemical, Intnl Paper Flipbook PDF

Rosin Ester Handbook Arizona Chemical, Intnl Paper

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January 2007

January 2007

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Table of Contents

Table of Contents

Chapter 1: Introduction to Rosin Esters ............................................. 5

Chapter 1: Introduction to Rosin Esters ............................................. 5

Chapter 2: Rosin Ester Chemistry ...................................................... 27

Chapter 2: Rosin Ester Chemistry ...................................................... 27

Chapter 3: Rosin Ester Kinetics .......................................................... 39

Chapter 3: Rosin Ester Kinetics .......................................................... 39

Chapter 4: Process Equipment ............................................................ 43

Chapter 4: Process Equipment ............................................................ 43

Chapter 5: Raw Materials and Formulation........................................ 57

Chapter 5: Raw Materials and Formulation........................................ 57

Chapter 6: Yields................................................................................. 77

Chapter 6: Yields................................................................................. 77

Chapter 7: Cycle Times....................................................................... 85

Chapter 7: Cycle Times....................................................................... 85

Chapter 8: Energy and Utilities........................................................... 103

Chapter 8: Energy and Utilities........................................................... 103

Chapter 9: Rosin Ester Economics...................................................... 127

Chapter 9: Rosin Ester Economics...................................................... 127

Chapter 10: Waste and By-Products ................................................... 143

Chapter 10: Waste and By-Products ................................................... 143

Chapter 11: Troubleshooting Guide.................................................... 149

Chapter 11: Troubleshooting Guide.................................................... 149

References ........................................................................................... 165

References ........................................................................................... 165

Appendices .......................................................................................... 171

Appendices .......................................................................................... 171

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Chapter 1: Introduction to Rosin Esters What is Rosin ....................................................................................................................................... 7 What is a Rosin Ester ........................................................................................................................... 9 Major Rosin Ester Applications ........................................................................................................... 10 Rosin Ester Properties ......................................................................................................................... 10 Flow Properties ...................................................................................................................... 10 Softening Point ........................................................................................................ 10 Viscosity .................................................................................................................. 11 Glass Transition Temperature.................................................................................. 12 Property Interactions................................................................................................ 12 Cold Flow ................................................................................................................ 13 Acid Number.......................................................................................................................... 13 Color ...................................................................................................................................... 14 Molecular Weight .................................................................................................................. 15 Solubility Parameter, Solubility and Cloud Point .................................................................. 16 Hydroxyl Value...................................................................................................................... 18 Iodine Value and Bromine Number ....................................................................................... 18 Stability .................................................................................................................................. 19 Spectral Properties ................................................................................................................. 20 Specific Gravity, Density ....................................................................................................... 20 Volatile Materials................................................................................................................... 21 Odor ....................................................................................................................................... 21 Thermal Properties................................................................................................................. 23 Vapor Pressure......................................................................................................... 23 Heat Capacity........................................................................................................... 24 Thermal Conductivity .............................................................................................. 24 Heat of Combustion ................................................................................................. 24 Hazard Information ................................................................................................................ 24 Flash Point ............................................................................................................... 24 Limiting Oxygen Concentration .............................................................................. 25 Auto-ignition Temperature ...................................................................................... 25 Dust Hazards............................................................................................................ 25

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Chapter 1: Introduction to Rosin Esters What is Rosin ....................................................................................................................................... 7 What is a Rosin Ester ........................................................................................................................... 9 Major Rosin Ester Applications ........................................................................................................... 10 Rosin Ester Properties ......................................................................................................................... 10 Flow Properties ...................................................................................................................... 10 Softening Point ........................................................................................................ 10 Viscosity .................................................................................................................. 11 Glass Transition Temperature.................................................................................. 12 Property Interactions................................................................................................ 12 Cold Flow ................................................................................................................ 13 Acid Number.......................................................................................................................... 13 Color ...................................................................................................................................... 14 Molecular Weight .................................................................................................................. 15 Solubility Parameter, Solubility and Cloud Point .................................................................. 16 Hydroxyl Value...................................................................................................................... 18 Iodine Value and Bromine Number ....................................................................................... 18 Stability .................................................................................................................................. 19 Spectral Properties ................................................................................................................. 20 Specific Gravity, Density ....................................................................................................... 20 Volatile Materials................................................................................................................... 21 Odor ....................................................................................................................................... 21 Thermal Properties................................................................................................................. 23 Vapor Pressure......................................................................................................... 23 Heat Capacity........................................................................................................... 24 Thermal Conductivity .............................................................................................. 24 Heat of Combustion ................................................................................................. 24 Hazard Information ................................................................................................................ 24 Flash Point ............................................................................................................... 24 Limiting Oxygen Concentration .............................................................................. 25 Auto-ignition Temperature ...................................................................................... 25 Dust Hazards............................................................................................................ 25

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Chapter 1: Introduction to Rosin Esters

Chapter 1: Introduction to Rosin Esters

What is Rosin

What is Rosin

Rosin is the name commonly applied to a group of resin acids that occurs in pine trees (genus Pinus) and, to a lesser extent, other conifers. It is a component of pine exudate (i.e., sap), a complex mixture of mono-, sesqui-, and diterpenoids, which accumulates at a tree’s wound site to kill insects and to flush and seal the injury. This exudate, commonly termed pine gum, is more correctly referred to as oleoresin (true gums such as gum Arabic and gum tragacanth are hydrophilic carbohydrates).

Rosin is the name commonly applied to a group of resin acids that occurs in pine trees (genus Pinus) and, to a lesser extent, other conifers. It is a component of pine exudate (i.e., sap), a complex mixture of mono-, sesqui-, and diterpenoids, which accumulates at a tree’s wound site to kill insects and to flush and seal the injury. This exudate, commonly termed pine gum, is more correctly referred to as oleoresin (true gums such as gum Arabic and gum tragacanth are hydrophilic carbohydrates).

Rosin containing materials such as oleoresin and pitch have been produced and used since antiquity. In fact, rosin is sometimes referred to as colophony, a term derived from resina colophonia (resin from Colophon). Colophon was an ancient Greek city situated on a small mountain between Lebedos and the port of Ephesos (in present day Turkey) whose inhabitants were traders in crude pine exudate. Archaeologists discovered a 3rd century Gallo-Roman ship which was carrying a cargo of pitch whose source was the Les Landes region of France. The pitch is thought to have been used for sealing or lining amphorae. The 4th century Roman statesman and poet Ausonius wrote about the tapping of pines for resin in Aquitania in the southeastern part of France. Marcus Graecus (circa 8th – 13th century) described the separation of rosin and turpentine by distillation. However rosin, as we know it, was isolated from oleoresin by alchemists using distillation some time around the 15th century. In the 17th century the term “naval stores” came into being in English records to describe the pine pitch and tar commodities used to waterproof rigging and to caulk sailing ships of the British Royal Navy. In fact, rosin and turpentine are still sometimes referred to as naval stores.

Rosin containing materials such as oleoresin and pitch have been produced and used since antiquity. In fact, rosin is sometimes referred to as colophony, a term derived from resina colophonia (resin from Colophon). Colophon was an ancient Greek city situated on a small mountain between Lebedos and the port of Ephesos (in present day Turkey) whose inhabitants were traders in crude pine exudate. Archaeologists discovered a 3rd century Gallo-Roman ship which was carrying a cargo of pitch whose source was the Les Landes region of France. The pitch is thought to have been used for sealing or lining amphorae. The 4th century Roman statesman and poet Ausonius wrote about the tapping of pines for resin in Aquitania in the southeastern part of France. Marcus Graecus (circa 8th – 13th century) described the separation of rosin and turpentine by distillation. However rosin, as we know it, was isolated from oleoresin by alchemists using distillation some time around the 15th century. In the 17th century the term “naval stores” came into being in English records to describe the pine pitch and tar commodities used to waterproof rigging and to caulk sailing ships of the British Royal Navy. In fact, rosin and turpentine are still sometimes referred to as naval stores.

The biosynthesis of resin acids is postulated to be derived from the cyclization of the C20 diterpene precursor, geranylgeranyl pyrophosphate1. These resin acids occur in a number of isomeric forms having the empirical formula C20H30O2 and some related structures2. The most prevalent acids are the conjugated abietic type acids (levopmaric, palustric, abietic, neoabietic and dehydroabietic acids) and non-conjugated pimaric type acids (pimaric, isopimaric and sandaracopimaric acids).

The biosynthesis of resin acids is postulated to be derived from the cyclization of the C20 diterpene precursor, geranylgeranyl pyrophosphate1. These resin acids occur in a number of isomeric forms having the empirical formula C20H30O2 and some related structures2. The most prevalent acids are the conjugated abietic type acids (levopmaric, palustric, abietic, neoabietic and dehydroabietic acids) and non-conjugated pimaric type acids (pimaric, isopimaric and sandaracopimaric acids).

Rosin is classified into three types, depending upon the process used to obtain it from the pine tree: gum, wood and tall oil. Currently, about 64% of global rosin production is gum rosin, about 33% is tall oil rosin with the remaining 3% being wood rosin.

Rosin is classified into three types, depending upon the process used to obtain it from the pine tree: gum, wood and tall oil. Currently, about 64% of global rosin production is gum rosin, about 33% is tall oil rosin with the remaining 3% being wood rosin.

Using a “modern” version of an ancient process, gum rosin is obtained from the sap (oleoresin) of a pine tree. In this method the living tree is wounded, the injury is treated with sulfuric acid to maintain liquid flow and the resulting oleoresin is collected in cups fastened below the wound. After collection, the oleoresin is diluted with gum turpentine (largely C10 monocyclic terpenes), filtered to remove trash, washed, decanted and steam distilled to yield gum rosin and gum turpentine. China is by far the largest producer of gum rosin worldwide (accounting for about 70%), followed by Indonesia and Brazil.

Using a “modern” version of an ancient process, gum rosin is obtained from the sap (oleoresin) of a pine tree. In this method the living tree is wounded, the injury is treated with sulfuric acid to maintain liquid flow and the resulting oleoresin is collected in cups fastened below the wound. After collection, the oleoresin is diluted with gum turpentine (largely C10 monocyclic terpenes), filtered to remove trash, washed, decanted and steam distilled to yield gum rosin and gum turpentine. China is by far the largest producer of gum rosin worldwide (accounting for about 70%), followed by Indonesia and Brazil.

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Wood rosin was introduced in 1910 as an alternative source for gum rosin. The Yaryan process, originally designed to extract linseed oil from flaxseed with petroleum hydrocarbons, was applied to the recovery of naval stores from pine stump wood3. Using this technique, wood rosin is obtained by solvent (hydrocarbon or MIBK) extraction of aged pine tree stumps that had been removed from the field, cleaned and shredded. After solvent removal the resulting crude wood rosin is then refined using two, immiscible solvents (e.g., hydrocarbon and furfural). The extracts are separated and the solvents stripped off. The hydrocarbon extract produces refined, decolorized wood rosin and the furfural extract yields dark fractions consisting of dark rosin (Belro®) and/or a phenolic-containing resin (Vinsol®). The volume of wood rosin products continues to decline with the only U.S. (and probably worldwide) producer being Pinova, a division of Hercules.

Wood rosin was introduced in 1910 as an alternative source for gum rosin. The Yaryan process, originally designed to extract linseed oil from flaxseed with petroleum hydrocarbons, was applied to the recovery of naval stores from pine stump wood3. Using this technique, wood rosin is obtained by solvent (hydrocarbon or MIBK) extraction of aged pine tree stumps that had been removed from the field, cleaned and shredded. After solvent removal the resulting crude wood rosin is then refined using two, immiscible solvents (e.g., hydrocarbon and furfural). The extracts are separated and the solvents stripped off. The hydrocarbon extract produces refined, decolorized wood rosin and the furfural extract yields dark fractions consisting of dark rosin (Belro®) and/or a phenolic-containing resin (Vinsol®). The volume of wood rosin products continues to decline with the only U.S. (and probably worldwide) producer being Pinova, a division of Hercules.

Tall oil (primarily a mixture of rosin and fatty acids) was first described by the Swede, Markt, in 1903. Its composition and vacuum distillation were reported in 1905 by Larsson. Tall oil was introduced as a commodity in this country in the early 1930’s. However, it made little impact on the American naval stores market until World War II when substitutes for inedible oils were needed3. Tall oil is derived from the sulfate or Kraft process for obtaining wood pulp from pine trees. The tree is chipped and the resulting wood chips are treated with aqueous sodium hydroxide and sodium sulfide at elevated temperatures to solubilize lignin thereby freeing the wood fibers. Along the way the long chain fatty glycerides are saponified and the rosin acids are converted to their sodium salts where they both end up in the aqueous “black liquor” fraction. These rosin and fatty acid salts or “soaps” are collected, acidulated (acidified) with sulfuric acid to yield CTO (crude tall oil), which is then fractionally distilled. The rosin acids fraction (tall oil rosin) obtained from CTO using this process is 30 – 35%; tall oil fatty acids, DTO, heads, pitch and losses account for the remaining 65 – 70%.

Tall oil (primarily a mixture of rosin and fatty acids) was first described by the Swede, Markt, in 1903. Its composition and vacuum distillation were reported in 1905 by Larsson. Tall oil was introduced as a commodity in this country in the early 1930’s. However, it made little impact on the American naval stores market until World War II when substitutes for inedible oils were needed3. Tall oil is derived from the sulfate or Kraft process for obtaining wood pulp from pine trees. The tree is chipped and the resulting wood chips are treated with aqueous sodium hydroxide and sodium sulfide at elevated temperatures to solubilize lignin thereby freeing the wood fibers. Along the way the long chain fatty glycerides are saponified and the rosin acids are converted to their sodium salts where they both end up in the aqueous “black liquor” fraction. These rosin and fatty acid salts or “soaps” are collected, acidulated (acidified) with sulfuric acid to yield CTO (crude tall oil), which is then fractionally distilled. The rosin acids fraction (tall oil rosin) obtained from CTO using this process is 30 – 35%; tall oil fatty acids, DTO, heads, pitch and losses account for the remaining 65 – 70%.

The distribution of resin acids among the three rosin types varies because of differing processing, wood storage and growing conditions as well as tree species. Even within a given type these factors can result in considerable variation in resin acid distribution. Table 1 shows typical distributions of common resin acids in the three types of U.S. rosins1.

The distribution of resin acids among the three rosin types varies because of differing processing, wood storage and growing conditions as well as tree species. Even within a given type these factors can result in considerable variation in resin acid distribution. Table 1 shows typical distributions of common resin acids in the three types of U.S. rosins1.

Table 1. Resin Acids Distribution in US Rosins Resin Acid Tall Oil Abietic 37.8 Dehydroabietic 18.2 Isopimaric 11.4 Palustric 8.2 Pimaric 4.4 Sandaracopimaric 3.9 Neoabietic 3.3 Communic 1.0 Levopimaric PAN Number* 49.3

Table 1. Resin Acids Distribution in US Rosins Resin Acid Tall Oil Abietic 37.8 Dehydroabietic 18.2 Isopimaric 11.4 Palustric 8.2 Pimaric 4.4 Sandaracopimaric 3.9 Neoabietic 3.3 Communic 1.0 Levopimaric PAN Number* 49.3

Wood 50.8 7.9 15.5 8.2 7.1 2.0 4.7 63.7

Gum 23.7 5.3 17.4 21.2 4.5 1.3 19.1 3.1 1.8 65.8

*Sum of palustric, abietic and neoabietic acids

Wood 50.8 7.9 15.5 8.2 7.1 2.0 4.7 63.7

Gum 23.7 5.3 17.4 21.2 4.5 1.3 19.1 3.1 1.8 65.8

*Sum of palustric, abietic and neoabietic acids

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In addition to rosin acids, tall oil rosin contains residual tall oil fatty acids (behenic, lignoceric, etc.) as well as some neutral and unsaponifiable materials. The neutrals consist of alcohols (largely sterols), hydrocarbons (decarboxylated rosin), aldehydes, anhydrides and esters. The unsaponifiables are similar to neutrals except that esters and anhydrides are saponified and thus not included in this determination. Thus the neutrals content is always equal to or higher than that of the unsaponifiables. The levels of fatty acids and neutrals vary depending upon the quality of the crude tall oil and the efficiency of the distillation process. Lastly, unlike gum and wood rosin, tall oil rosin contains about 500 ppm of sulfur compounds resulting form the Kraft pulping process. Table 2 shows the typical composition and property ranges of U.S. tall oil rosin. Table 2. Typical U.S. Tall Oil Rosin Composition / Properties Component Level Rosin Acids (%) 93 - 97 Fatty Acids (%) 1-4 Neutrals (%) 2-4 Sulfur (ppm) 400 - 1000 Property Typical Value Acid Number 170 – 182 Softening Point, R&B (°C) 75 – 80 Color, Gardner 4–6

In addition to rosin acids, tall oil rosin contains residual tall oil fatty acids (behenic, lignoceric, etc.) as well as some neutral and unsaponifiable materials. The neutrals consist of alcohols (largely sterols), hydrocarbons (decarboxylated rosin), aldehydes, anhydrides and esters. The unsaponifiables are similar to neutrals except that esters and anhydrides are saponified and thus not included in this determination. Thus the neutrals content is always equal to or higher than that of the unsaponifiables. The levels of fatty acids and neutrals vary depending upon the quality of the crude tall oil and the efficiency of the distillation process. Lastly, unlike gum and wood rosin, tall oil rosin contains about 500 ppm of sulfur compounds resulting form the Kraft pulping process. Table 2 shows the typical composition and property ranges of U.S. tall oil rosin. Table 2. Typical U.S. Tall Oil Rosin Composition / Properties Component Level Rosin Acids (%) 93 - 97 Fatty Acids (%) 1-4 Neutrals (%) 2-4 Sulfur (ppm) 400 - 1000 Property Typical Value Acid Number 170 – 182 Softening Point, R&B (°C) 75 – 80 Color, Gardner 4–6

While gum and wood rosins contain very little fatty acids, they do contain different types of neutrals. Gum rosin contains 5 – 10% high molecular weight terpenes such as α-terpineol, methyl chavicol and longifolene. Wood rosin includes about 11% diterpene hydrocarbons and alcohols; about one fifth of these neutrals are highly hindered aromatics.

While gum and wood rosins contain very little fatty acids, they do contain different types of neutrals. Gum rosin contains 5 – 10% high molecular weight terpenes such as α-terpineol, methyl chavicol and longifolene. Wood rosin includes about 11% diterpene hydrocarbons and alcohols; about one fifth of these neutrals are highly hindered aromatics.

By definition, rosin acids contain carboxylic acid functionality and thus display weak acidity. However the insolubility of rosin acids in water makes determination of their dissociation constants difficult. A Ka value of 2.5 x 10-6 has been reported; for comparison acetic acid has a Ka of about 1.8 x 10-5. The formation of salts from their reaction with inorganic bases is a key step in the metal salt catalysis of rosin esterification.

By definition, rosin acids contain carboxylic acid functionality and thus display weak acidity. However the insolubility of rosin acids in water makes determination of their dissociation constants difficult. A Ka value of 2.5 x 10-6 has been reported; for comparison acetic acid has a Ka of about 1.8 x 10-5. The formation of salts from their reaction with inorganic bases is a key step in the metal salt catalysis of rosin esterification.

What is a Rosin Ester

What is a Rosin Ester

Esterification is one of the best known transformations in organic chemistry. The condensation reaction of a carboxylic acid and an alcohol yields an ester plus water as shown in the schematic below.

Esterification is one of the best known transformations in organic chemistry. The condensation reaction of a carboxylic acid and an alcohol yields an ester plus water as shown in the schematic below.

RCO2H + R’OH

RCO2R’ + H2O

RCO2H + R’OH

RCO2R’ + H2O

When the carboxylic acid is rosin, a rosin ester is formed. For example if glycerin is used as the alcohol, the resultant ester is the glycerin ester of rosin. It is important that the water formed be removed since the reaction is reversible. Rosin esters were synthesized as early as the 1880’s by the German chemist Eugen Schaal4. These esters were used as substitutes for copal and other

When the carboxylic acid is rosin, a rosin ester is formed. For example if glycerin is used as the alcohol, the resultant ester is the glycerin ester of rosin. It is important that the water formed be removed since the reaction is reversible. Rosin esters were synthesized as early as the 1880’s by the German chemist Eugen Schaal4. These esters were used as substitutes for copal and other

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Arizona Chemical Confidential – Do Not Copy

natural resins in the manufacture of varnishes. The glycerin ester of colophony (gum rosin) was often employed for this purpose5. Pentaerythritol (often abbreviated PE) esters were introduced in the 1930s and imparted improved varnish properties.

natural resins in the manufacture of varnishes. The glycerin ester of colophony (gum rosin) was often employed for this purpose5. Pentaerythritol (often abbreviated PE) esters were introduced in the 1930s and imparted improved varnish properties.

Major Rosin Ester Applications

Major Rosin Ester Applications

By far the largest use of rosin esters in the adhesives’ industry is that of a “tackifier” (it is sometimes called a tackifier resin). A tackifier is an amorphous, polymer modifier for a class of adhesives known as resin/rubber adhesives since the major components are a resin (tackifier) and a rubber (polymer). Tackifying resins are divided into three groups: petrochemical hydrocarbon resins, rosin resins and terpene resins. Applications include pressure sensitive tapes and labels, non-wovens, hot melt packaging and bookbinding adhesives, construction adhesives, etc. Additional uses of rosin esters are in the chewing gum, coating, investment casting and emulsifier industries.

By far the largest use of rosin esters in the adhesives’ industry is that of a “tackifier” (it is sometimes called a tackifier resin). A tackifier is an amorphous, polymer modifier for a class of adhesives known as resin/rubber adhesives since the major components are a resin (tackifier) and a rubber (polymer). Tackifying resins are divided into three groups: petrochemical hydrocarbon resins, rosin resins and terpene resins. Applications include pressure sensitive tapes and labels, non-wovens, hot melt packaging and bookbinding adhesives, construction adhesives, etc. Additional uses of rosin esters are in the chewing gum, coating, investment casting and emulsifier industries.

In pressure sensitive adhesive (PSA) applications the tackifier lowers the modulus (softens), increases the glass transition temperature and alters the polarity of the polymer to allow the blend to form an adhesive bond. Depending upon the polymer, the level of tackifier used can range from 10% in an acrylic to 60 % in a styrenic block polymer. Typical examples are PSA paper labels, PSA tapes and diaper (non-woven) assembly adhesives.

In pressure sensitive adhesive (PSA) applications the tackifier lowers the modulus (softens), increases the glass transition temperature and alters the polarity of the polymer to allow the blend to form an adhesive bond. Depending upon the polymer, the level of tackifier used can range from 10% in an acrylic to 60 % in a styrenic block polymer. Typical examples are PSA paper labels, PSA tapes and diaper (non-woven) assembly adhesives.

In hot melt packaging and bookbinding applications, the tackifier lowers the adhesive viscosity, improves wet out and adjusts the glass transition temperature (Tg). The most common formulations consist of an ethylene vinyl acetate (EVA) polymer, wax and tackifier.

In hot melt packaging and bookbinding applications, the tackifier lowers the adhesive viscosity, improves wet out and adjusts the glass transition temperature (Tg). The most common formulations consist of an ethylene vinyl acetate (EVA) polymer, wax and tackifier.

Construction adhesives are solvent or water-based adhesives based on SBR (styrene-butadiene rubber), tackifier and a high loading of filler (clay or calcium carbonate). The resins in these applications can provide wet out as well as act as a binder. Low cost is a requirement in this market so low cost, dark resins are often used.

Construction adhesives are solvent or water-based adhesives based on SBR (styrene-butadiene rubber), tackifier and a high loading of filler (clay or calcium carbonate). The resins in these applications can provide wet out as well as act as a binder. Low cost is a requirement in this market so low cost, dark resins are often used.

Rosin Ester Properties

Rosin Ester Properties

While softening point, acid number and color are the most commonly reported rosin ester properties, there are several others used to characterize them as well. These include glass transition temperature, viscosity, molecular weight, hydroxyl value, solubility parameter, density, heat capacity, thermal conductivity, etc.

While softening point, acid number and color are the most commonly reported rosin ester properties, there are several others used to characterize them as well. These include glass transition temperature, viscosity, molecular weight, hydroxyl value, solubility parameter, density, heat capacity, thermal conductivity, etc.

Flow Properties – Softening point, melt viscosity and glass transition temperature are all related in that they are impacted by molecular motion. Because all of these can be considered flow properties, this section will discuss each of these phenomena in detail and attempt to define their relationships.

Flow Properties – Softening point, melt viscosity and glass transition temperature are all related in that they are impacted by molecular motion. Because all of these can be considered flow properties, this section will discuss each of these phenomena in detail and attempt to define their relationships.

Softening Point - Unlike pure rosin acids, the corresponding rosin esters are amorphous (i.e., they have no crystalline structure) and therefore have no true melting points. The property most often used to describe the liquid-solid relationship is Ring & Ball Softening Point (a less popular

Softening Point - Unlike pure rosin acids, the corresponding rosin esters are amorphous (i.e., they have no crystalline structure) and therefore have no true melting points. The property most often used to describe the liquid-solid relationship is Ring & Ball Softening Point (a less popular

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method, the Hercules Drop Softening Point, gives results about 8 - 10°C higher than the R & B method). R & B Softening Point is defined as the temperature at which a disc of resin (supported in a metal ring) flows one inch under the weight of a steel ball as the sample is heated at a defined rate. Currently, most softening points are determined automatically using a Mettler Dropping Point instrument which has been calibrated using a R & B Softening Point apparatus.

method, the Hercules Drop Softening Point, gives results about 8 - 10°C higher than the R & B method). R & B Softening Point is defined as the temperature at which a disc of resin (supported in a metal ring) flows one inch under the weight of a steel ball as the sample is heated at a defined rate. Currently, most softening points are determined automatically using a Mettler Dropping Point instrument which has been calibrated using a R & B Softening Point apparatus.

Several formulae can be used to calculate the softening point (or glass transition temperature) of a blend of two different rosin esters. A widely used relationship is the Fox equation shown below. 1/SP = W1/SP1 + W2/SP2

Several formulae can be used to calculate the softening point (or glass transition temperature) of a blend of two different rosin esters. A widely used relationship is the Fox equation shown below. 1/SP = W1/SP1 + W2/SP2

In this formula SP = softening point of the blend in degrees Kelvin, W1 = weight fraction of ester 1, SP1 = softening point of ester 1 in degrees Kelvin, W2 = weight fraction of ester 2 and SP2 = softening point of ester 2 in degrees Kelvin. Employing a simple, linear algebraic sum gives results that are about 7% too high at a 1:1 blend ratio.

In this formula SP = softening point of the blend in degrees Kelvin, W1 = weight fraction of ester 1, SP1 = softening point of ester 1 in degrees Kelvin, W2 = weight fraction of ester 2 and SP2 = softening point of ester 2 in degrees Kelvin. Employing a simple, linear algebraic sum gives results that are about 7% too high at a 1:1 blend ratio.

Viscosity – Rosin derivatives are processed, delivered and/or used in the molten state. Since the different resins have different softening points, their temperature-viscosity responses are different. The most common means of providing this information is by the use of temperatureviscosity charts, wherein the resin’s viscosity is plotted against temperature. This relationship is determined by a combination of a viscometer (e.g. Brookfield) and a heated, constant temperature cell (e.g. Brookfield Thermosel®). The temperature-viscosity profiles of a series of rosin esters are shown in the Table 3 below:

Viscosity – Rosin derivatives are processed, delivered and/or used in the molten state. Since the different resins have different softening points, their temperature-viscosity responses are different. The most common means of providing this information is by the use of temperatureviscosity charts, wherein the resin’s viscosity is plotted against temperature. This relationship is determined by a combination of a viscometer (e.g. Brookfield) and a heated, constant temperature cell (e.g. Brookfield Thermosel®). The temperature-viscosity profiles of a series of rosin esters are shown in the Table 3 below:

Table 3. Typical Rosin Ester Temperature – Viscosity Profiles Soft. Point Viscosity (cps) Rosin Ester (°C) 125°C 150°C 177°C ST RE 25 23 40 ST RE 85 83 2,500 500 70 ST RE 100 97 11,800 955 150 SL RE 110L 107 38,300 2,110 300

Table 3. Typical Rosin Ester Temperature – Viscosity Profiles Soft. Point Viscosity (cps) Rosin Ester (°C) 125°C 150°C 177°C ST RE 25 23 40 ST RE 85 83 2,500 500 70 ST RE 100 97 11,800 955 150 SL RE 110L 107 38,300 2,110 300

190°C 80 150

If we consider softening point to be a type of viscosity measurement, there should be a relationship between the two. Work done by Xinya Lu at Arizona’s research laboratory in 1998 found the following relationship between a tackifier resin’s viscosity at a given temperature and its softening point6. Using this formula one can develop a temperature-viscosity profile for a resin of known softening point. In this general equation V = viscosity (cps) at temperature T (°C) and SP = resin softening point (°C).

V = 10

-1+ (C1/ (C2+T-SP))

190°C 80 150

If we consider softening point to be a type of viscosity measurement, there should be a relationship between the two. Work done by Xinya Lu at Arizona’s research laboratory in 1998 found the following relationship between a tackifier resin’s viscosity at a given temperature and its softening point6. Using this formula one can develop a temperature-viscosity profile for a resin of known softening point. In this general equation V = viscosity (cps) at temperature T (°C) and SP = resin softening point (°C).

V = 10

-1+ (C1/ (C2+T-SP))

To verify this formula, viscosity-temperature data from a series of rosin PE esters (Sylvatac RE 100, Sylvalite RE 100L and Sylvalite RE 100XL) were fitted to this equation. As shown below the coefficient C1 varied slightly from Lu’s general formula while C2 remained constant. While this equation is valid for most tackifier types, the coefficients may have to be adjusted to obtain

To verify this formula, viscosity-temperature data from a series of rosin PE esters (Sylvatac RE 100, Sylvalite RE 100L and Sylvalite RE 100XL) were fitted to this equation. As shown below the coefficient C1 varied slightly from Lu’s general formula while C2 remained constant. While this equation is valid for most tackifier types, the coefficients may have to be adjusted to obtain

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more accurate results (e.g. for polyterpene resins Lu calculated C1 = 504 and C2 = 67.6). Please refer to Table 4: Table 4. Viscosity Prediction Constants Lu’s General Tackifier Coefficients 98°C SP Rosin PE Ester Coefficients

more accurate results (e.g. for polyterpene resins Lu calculated C1 = 504 and C2 = 67.6). Please refer to Table 4: Table 4. Viscosity Prediction Constants

C1 477 465

C2 66.2 66.2

Lu’s General Tackifier Coefficients 98°C SP Rosin PE Ester Coefficients

C1 477 465

C2 66.2 66.2

Interestingly, application of this equation indicates that the viscosity of a resin at its R & B softening point is approximately 1.6 million cps.

Interestingly, application of this equation indicates that the viscosity of a resin at its R & B softening point is approximately 1.6 million cps.

Glass Transition Temperature - The glass transition temperature (Tg) of an amorphous material may be described as that temperature at which it changes from a “frozen” or glassy state to one of increased molecular motion. It is a measure of the amount of room, or free volume, required for the molecule or part of it to move about. The Tg usually is measured by differential scanning calorimetry (DSC) or, less often, by dynamic mechanical analysis (DMA). Tan δ is a rheological measurement which may be considered to be the ratio of a resin’s hardness to softness whose peak temperature corresponds to a type of glass transition temperature. An ester’s Ring & Ball Softening Point is directly proportional to its Tg. The R & B Softening Point of a rosin ester (and of most amorphous tackifier resins) is about 50°C higher than its Tg (DSC) as shown in the chart in APPENDIX I. The precisions for softening point, Tg (DSC) and Tg (DMA) determinations are 0.31, 0.60 and 0.87, respectively. Thus softening point is the most precise determination of the aforementioned determinations.

Glass Transition Temperature - The glass transition temperature (Tg) of an amorphous material may be described as that temperature at which it changes from a “frozen” or glassy state to one of increased molecular motion. It is a measure of the amount of room, or free volume, required for the molecule or part of it to move about. The Tg usually is measured by differential scanning calorimetry (DSC) or, less often, by dynamic mechanical analysis (DMA). Tan δ is a rheological measurement which may be considered to be the ratio of a resin’s hardness to softness whose peak temperature corresponds to a type of glass transition temperature. An ester’s Ring & Ball Softening Point is directly proportional to its Tg. The R & B Softening Point of a rosin ester (and of most amorphous tackifier resins) is about 50°C higher than its Tg (DSC) as shown in the chart in APPENDIX I. The precisions for softening point, Tg (DSC) and Tg (DMA) determinations are 0.31, 0.60 and 0.87, respectively. Thus softening point is the most precise determination of the aforementioned determinations.

Property Interactions – The number of alcohol groups on the polyol (e.g., two for ethylene glycol, three for glycerin and four for pentaerythritol) determines the maximum number of rosin acids that can be reacted and, in turn, the molecular weight of the ester. While one would expect that the softening point, viscosity and Tg of a rosin ester would be proportional to its molecular weight, this only is true where additional rosin molecules are added to a similar polyol, in which case each additional rosin ester group increases the softening point by about 20°C. Thus the structure of the polyol and resultant rosin ester is critical. For example, compare the molecular weights and softening points of the ethylene glycol, diethylene glycol and triethylene glycol rosin diesters in Table 5.

Property Interactions – The number of alcohol groups on the polyol (e.g., two for ethylene glycol, three for glycerin and four for pentaerythritol) determines the maximum number of rosin acids that can be reacted and, in turn, the molecular weight of the ester. While one would expect that the softening point, viscosity and Tg of a rosin ester would be proportional to its molecular weight, this only is true where additional rosin molecules are added to a similar polyol, in which case each additional rosin ester group increases the softening point by about 20°C. Thus the structure of the polyol and resultant rosin ester is critical. For example, compare the molecular weights and softening points of the ethylene glycol, diethylene glycol and triethylene glycol rosin diesters in Table 5.

Table 5. Impact of Alcohol Structure on Rosin Ester Properties Alcohol / Polyol Number of –OH Approximate Ester Employed Groups Molecular Weight Methanol 1 314 Ethylene Glycol 2 626 Diethylene Glycol 2 670 Triethylene Glycol 2 714 Glycerin 3 938 Pentaerythritol 4 1266

Table 5. Impact of Alcohol Structure on Rosin Ester Properties Alcohol / Polyol Number of –OH Approximate Ester Employed Groups Molecular Weight Methanol 1 314 Ethylene Glycol 2 626 Diethylene Glycol 2 670 Triethylene Glycol 2 714 Glycerin 3 938 Pentaerythritol 4 1266

Typical Ester Softening Point (°°C) Liquid 40 25 10 85 100

Typical Ester Softening Point (°°C) Liquid 40 25 10 85 100

In this instance the addition of each -CH2-CH2-O- segment between the two rosins decreases the softening point (or Tg) by about 15°C as a result of the reduced rigidity (or increased flexibility)

In this instance the addition of each -CH2-CH2-O- segment between the two rosins decreases the softening point (or Tg) by about 15°C as a result of the reduced rigidity (or increased flexibility)

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Arizona Chemical Confidential – Do Not Copy

of the ester molecule. If one assumes similar intermolecular forces for most rosin esters, this is best explained by the concept of free volume. As stated previously the softening point, viscosity and Tg are related to molecular mobility which, in turn is dependent upon free volume. As the free volume increases, the values of these properties decrease. Using the glass transition temperature as a reference, the free volume of a material may be estimated by the following formula7.

of the ester molecule. If one assumes similar intermolecular forces for most rosin esters, this is best explained by the concept of free volume. As stated previously the softening point, viscosity and Tg are related to molecular mobility which, in turn is dependent upon free volume. As the free volume increases, the values of these properties decrease. Using the glass transition temperature as a reference, the free volume of a material may be estimated by the following formula7.

fT = fg + αf (T-Tg)

fT = fg + αf (T-Tg)

Where fT = fractional free volume at temperature T, fg = fractional free volume at Tg (about 0.025 or 2.5%) and αf = coefficient of thermal expansion of the fractional free volume above the Tg (about 4.8 x 10-4 °C-1). Picking T = 100°C, the data in Table 6 compares the calculated fractional free volumes of rosin ethylene glycol and triethylene glycol esters.

Where fT = fractional free volume at temperature T, fg = fractional free volume at Tg (about 0.025 or 2.5%) and αf = coefficient of thermal expansion of the fractional free volume above the Tg (about 4.8 x 10-4 °C-1). Picking T = 100°C, the data in Table 6 compares the calculated fractional free volumes of rosin ethylene glycol and triethylene glycol esters.

Table 6. Impact of Alcohol Type on Rosin Ester Fractional Free Volume Rosin Ester Tg (°C) Fractional Free Volume at 100°C Ethylene Glycol 10 6.8% Triethylene Glycol - 20 8.3%

Table 6. Impact of Alcohol Type on Rosin Ester Fractional Free Volume Rosin Ester Tg (°C) Fractional Free Volume at 100°C Ethylene Glycol 10 6.8% Triethylene Glycol - 20 8.3%

The log of the viscosity is inversely proportional to the fractional free volume. Thus the higher the fractional free volume at a given temperature, the lower the viscosity. So despite a higher molecular weight, the triethylene glycol ester of rosin has a higher free volume and thus a lower softening point and viscosity than the ethylene glycol ester.

The log of the viscosity is inversely proportional to the fractional free volume. Thus the higher the fractional free volume at a given temperature, the lower the viscosity. So despite a higher molecular weight, the triethylene glycol ester of rosin has a higher free volume and thus a lower softening point and viscosity than the ethylene glycol ester.

Cold Flow - A related phenomenon, “cold flow” or “blocking” is the relatively slow remassing of flaked or pastillated resin which occurs during storage. It is impacted by Tg, time, temperature, and pressure. Cold flow is of importance when bags of flaked rosin ester (or other resin) become solid masses and can no longer be readily emptied by the end-user. To prevent cold flow the flaked resin must be flaked and stored at temperatures where this process will not occur during a specified period. Based on a comparison of data of different rosin esters one can use a rule of thumb that the resin should be stored at temperatures 5 - 10°C below its Tg to prevent significant cold flow and remassing. It is thought that the storage temperature should be below the Tg because of pressure from the stacking of bags or super sacks. Glycerin esters with their relatively low Tg are prone to cold flow and remassing whereas PE esters are not.

Cold Flow - A related phenomenon, “cold flow” or “blocking” is the relatively slow remassing of flaked or pastillated resin which occurs during storage. It is impacted by Tg, time, temperature, and pressure. Cold flow is of importance when bags of flaked rosin ester (or other resin) become solid masses and can no longer be readily emptied by the end-user. To prevent cold flow the flaked resin must be flaked and stored at temperatures where this process will not occur during a specified period. Based on a comparison of data of different rosin esters one can use a rule of thumb that the resin should be stored at temperatures 5 - 10°C below its Tg to prevent significant cold flow and remassing. It is thought that the storage temperature should be below the Tg because of pressure from the stacking of bags or super sacks. Glycerin esters with their relatively low Tg are prone to cold flow and remassing whereas PE esters are not.

Acid Number - Acid number (AN) is a measure of the concentration of rosin carboxylic acids

Acid Number - Acid number (AN) is a measure of the concentration of rosin carboxylic acids

(expressed as mg KOH/gm resin). Expressed another way, the AN divided by 56,100 equals the COOH concentration in equivalents/gm. Therefore the AN of an ester is a measure of the amount of unreacted rosin acid remaining after esterification and since there is always unreacted rosin present, rosin esters have an acid number. While typical acid numbers of commercial rosin esters range from 5 – 15, in some instances high ANs are desirable. In these cases partial esters are prepared with ANs in the 40 – 50 region. The acid number of a blend of two (or more) different rosin esters can be calculated by the algebraic sum of the acid numbers of the different esters.

(expressed as mg KOH/gm resin). Expressed another way, the AN divided by 56,100 equals the COOH concentration in equivalents/gm. Therefore the AN of an ester is a measure of the amount of unreacted rosin acid remaining after esterification and since there is always unreacted rosin present, rosin esters have an acid number. While typical acid numbers of commercial rosin esters range from 5 – 15, in some instances high ANs are desirable. In these cases partial esters are prepared with ANs in the 40 – 50 region. The acid number of a blend of two (or more) different rosin esters can be calculated by the algebraic sum of the acid numbers of the different esters.

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Arizona Chemical Confidential – Do Not Copy

Color - While the softening point and acid number of a rosin ester can significantly affect its end-use performance, its color is strictly an esthetic property. That is, a dark resin may perform just as well as a light-colored one but it may be deemed unsuitable because of its color. Rosin ester color can be determined and reported in a number of ways. The classical method is based on the US Department of Agriculture (USDA) system. In this case a 7/8” cube of resin is compared with standard glass cubes supplied by the USDA; the colors range from D to XC.

Color - While the softening point and acid number of a rosin ester can significantly affect its end-use performance, its color is strictly an esthetic property. That is, a dark resin may perform just as well as a light-colored one but it may be deemed unsuitable because of its color. Rosin ester color can be determined and reported in a number of ways. The classical method is based on the US Department of Agriculture (USDA) system. In this case a 7/8” cube of resin is compared with standard glass cubes supplied by the USDA; the colors range from D to XC.

However the most popular methodology is the Gardner system that has been standardized in ASTM method D1544 and AOCS Method Td 1a. The sample of molten resin, in a specifically sized glass tube, is compared against colored glass standards in a comparator. This device allows the tube containing the resin to be situated between the standards for ease of comparison. The colors range from 1 to 18. The picture below compares USDA and Gardner colors and a conversion chart for USDA to Gardner color is shown in APPENDIX II.

However the most popular methodology is the Gardner system that has been standardized in ASTM method D1544 and AOCS Method Td 1a. The sample of molten resin, in a specifically sized glass tube, is compared against colored glass standards in a comparator. This device allows the tube containing the resin to be situated between the standards for ease of comparison. The colors range from 1 to 18. The picture below compares USDA and Gardner colors and a conversion chart for USDA to Gardner color is shown in APPENDIX II.

The Gardner color of a blend of different colored rosin esters cannot be easily calculated because Gardner colors are not linear. An estimate can be made by 1) correlating Gardner color to a linear scale like potassium dichromate or iodine color, 2) determining the algebraic sum of the potassium dichromate or iodine colors and 3) converting this value back to Gardner color.

The Gardner color of a blend of different colored rosin esters cannot be easily calculated because Gardner colors are not linear. An estimate can be made by 1) correlating Gardner color to a linear scale like potassium dichromate or iodine color, 2) determining the algebraic sum of the potassium dichromate or iodine colors and 3) converting this value back to Gardner color.

In Europe the Gardner color is usually reported as the color of a 50% solution of the resin in toluene instead of molten as in the US. The Gardner color of a 50% resin solution can be approximated from the molten or “neat” color by the following equation:

In Europe the Gardner color is usually reported as the color of a 50% solution of the resin in toluene instead of molten as in the US. The Gardner color of a 50% resin solution can be approximated from the molten or “neat” color by the following equation:

50% Solution Gardner Color = (0.96 x Neat Gardner Color) – 1.50

50% Solution Gardner Color = (0.96 x Neat Gardner Color) – 1.50

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Arizona Chemical Confidential – Do Not Copy

However there can be a drawback to using solution colors because in some instances a phenomenon called “solvent darkening” will occur. In this case the color of the resin solution is significantly darker than expected (sometimes even darker than the neat resin) presumably because of an interaction or complex with the solvent.

However there can be a drawback to using solution colors because in some instances a phenomenon called “solvent darkening” will occur. In this case the color of the resin solution is significantly darker than expected (sometimes even darker than the neat resin) presumably because of an interaction or complex with the solvent.

Lastly, there are spectrophotometic methods of determining the color. In these cases selected absorptions in the visible spectrum of the material are mathematically converted to Gardner colors that are more precise than the visual comparative methods. Such an instrument is available from Minolta.

Lastly, there are spectrophotometic methods of determining the color. In these cases selected absorptions in the visible spectrum of the material are mathematically converted to Gardner colors that are more precise than the visual comparative methods. Such an instrument is available from Minolta.

There are times when rosin esters have unacceptable “green” tints or hues that originate from equipment or raw materials. In PE esters, oxidation resulting from reactor air leaks, especially in the sparge lines or dry chargers, can be the source of green color8. Rosin (or other raw material) containing iron results in green iron salts. Fumarated rosin glycerin esters can have green colors in the resultant ester; this has happened even though no analytical anomalies were found but the type of disproportionation agent appeared to impact the color. In this case, Lowinox® TBM6 appeared to impart the least green tint to the ester.

There are times when rosin esters have unacceptable “green” tints or hues that originate from equipment or raw materials. In PE esters, oxidation resulting from reactor air leaks, especially in the sparge lines or dry chargers, can be the source of green color8. Rosin (or other raw material) containing iron results in green iron salts. Fumarated rosin glycerin esters can have green colors in the resultant ester; this has happened even though no analytical anomalies were found but the type of disproportionation agent appeared to impact the color. In this case, Lowinox® TBM6 appeared to impart the least green tint to the ester.

Molecular Weight – The molecular weight of a rosin ester would appear to be simply that of

Molecular Weight – The molecular weight of a rosin ester would appear to be simply that of

the subject molecule (e.g., methyl rosinate). However it is not that simple if the alcohol is a polyol, that is it contains more than one –OH group. In these instances, the polyol molecules may have different numbers of rosin acid group attached. Thus an ethylene glycol can have either one or two rosin molecules attached; pentaerythritol can have one, two, three or four rosins attached. These moieties are known as mono-, di-, tri- and tetraesters, respectively. The distribution of these various esters is governed by the equivalents of polyol used per equivalent of rosin (refer to the Alcohols / Polyols section in Chapter 5). The amounts of each of these ester species can be quantitatively determined using size exclusion / gel permeation chromatography (GPC). In addition to the various mono-, di-, etc. esters, decarboxylated rosin (“lights”), rosin and high molecular weight species (“highers”) can be seen. As will be discussed later, the “highers” originate from maleic / fumaric adduction and/or from such side reactions as polyol etherification and/or rosin dimerization. The GPC retention times for the various ester species are shown in the Table 7. Note that these assignments are made using the small pore GPC columns in use in Arizona’s Analytical Group as of June, 2005 and are subject to change. An example of a pentaerythritol rosin ester GPC with assignments is shown in APPENDIX III. Table 7. Rosin Ester GPC Assignments Component Retention Time Range (minutes) Lights (Rosin Oils) 25.4 – 26.9 Rosin Acids 24.4 – 24.8 Monoester 23.5 – 24.1 Diester 22.5 – 22.9 Triester 21.9 – 22.3 Tetraester 21.4 – 21.7 Highers (Larger Than Tetraester) 15.0 – 20.9

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the subject molecule (e.g., methyl rosinate). However it is not that simple if the alcohol is a polyol, that is it contains more than one –OH group. In these instances, the polyol molecules may have different numbers of rosin acid group attached. Thus an ethylene glycol can have either one or two rosin molecules attached; pentaerythritol can have one, two, three or four rosins attached. These moieties are known as mono-, di-, tri- and tetraesters, respectively. The distribution of these various esters is governed by the equivalents of polyol used per equivalent of rosin (refer to the Alcohols / Polyols section in Chapter 5). The amounts of each of these ester species can be quantitatively determined using size exclusion / gel permeation chromatography (GPC). In addition to the various mono-, di-, etc. esters, decarboxylated rosin (“lights”), rosin and high molecular weight species (“highers”) can be seen. As will be discussed later, the “highers” originate from maleic / fumaric adduction and/or from such side reactions as polyol etherification and/or rosin dimerization. The GPC retention times for the various ester species are shown in the Table 7. Note that these assignments are made using the small pore GPC columns in use in Arizona’s Analytical Group as of June, 2005 and are subject to change. An example of a pentaerythritol rosin ester GPC with assignments is shown in APPENDIX III. Table 7. Rosin Ester GPC Assignments Component Retention Time Range (minutes) Lights (Rosin Oils) 25.4 – 26.9 Rosin Acids 24.4 – 24.8 Monoester 23.5 – 24.1 Diester 22.5 – 22.9 Triester 21.9 – 22.3 Tetraester 21.4 – 21.7 Highers (Larger Than Tetraester) 15.0 – 20.9

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Since a rosin ester has several components with different molecular weights, there is a molecular weight distribution. The number average (Mn), the weight average (Mw), and the z-average (Mz) molecular weights as well as the polydispersity can be obtained from GPC analysis. The general formula for the above distributions is shown below.

Since a rosin ester has several components with different molecular weights, there is a molecular weight distribution. The number average (Mn), the weight average (Mw), and the z-average (Mz) molecular weights as well as the polydispersity can be obtained from GPC analysis. The general formula for the above distributions is shown below.

Mol. Wt. = ΣniMix/ ΣniMix-1

Mol. Wt. = ΣniMix/ ΣniMix-1

When x=1, the distribution is Mn; x=2 is Mw; x=3 is Mz. These are the first, second and third moments of the molecular weight. Polydispersity (P.D.) is a measure of the distribution and is defined as Mw/Mn. The typical GPC molecular weights and polydispersities of some selected rosin esters are shown in Table 8.

When x=1, the distribution is Mn; x=2 is Mw; x=3 is Mz. These are the first, second and third moments of the molecular weight. Polydispersity (P.D.) is a measure of the distribution and is defined as Mw/Mn. The typical GPC molecular weights and polydispersities of some selected rosin esters are shown in Table 8.

Table 8. Rosin Ester GPC Molecular Weight Data Rosin Ester Mn Mw Mz Pentaerythritol 828 1008 1182 Glycerin 625 751 895 Trimethylolpropane 672 776 885 Ethylene glycol 563 653 755 Triethylene glycol 535 611 689

P.D. 1.218 1.203 1.154 1.161 1.141

Table 8. Rosin Ester GPC Molecular Weight Data Rosin Ester Mn Mw Mz Pentaerythritol 828 1008 1182 Glycerin 625 751 895 Trimethylolpropane 672 776 885 Ethylene glycol 563 653 755 Triethylene glycol 535 611 689

P.D. 1.218 1.203 1.154 1.161 1.141

It important to note that polystyrene standards are used to calculate the rosin ester’s GPC derived molecular weights. Because the hydrodynamic volumes of rosin esters are different than those of the polystyrene standards, the GPC molecular weights are lower than the actual ones. For example the GPC derived Mn of the various rosin species are about 23% too low as shown by the graph in APPENDIX IV.

It important to note that polystyrene standards are used to calculate the rosin ester’s GPC derived molecular weights. Because the hydrodynamic volumes of rosin esters are different than those of the polystyrene standards, the GPC molecular weights are lower than the actual ones. For example the GPC derived Mn of the various rosin species are about 23% too low as shown by the graph in APPENDIX IV.

Since the major application of rosin esters is as polymer modifiers (tackifiers), polymer compatibility is a key property. Molecular weight and molecular weight distribution are chief contributors to resin-polymer compatibility (in addition to solubility parameter). The lower the molecular weight and the narrower the distribution (polydispersity), the better the polymer compatibility of the ester. Thus a rosin ester’s performance as a tackifier is strongly dependent on these properties.

Since the major application of rosin esters is as polymer modifiers (tackifiers), polymer compatibility is a key property. Molecular weight and molecular weight distribution are chief contributors to resin-polymer compatibility (in addition to solubility parameter). The lower the molecular weight and the narrower the distribution (polydispersity), the better the polymer compatibility of the ester. Thus a rosin ester’s performance as a tackifier is strongly dependent on these properties.

Solubility Parameter, Solubility and Cloud Point – As stated above solubility parameter, δ, is one of the major factors that define the compatibility of a rosin ester with a given polymer, the others being molecular weight / molecular weight distribution and enthalpy (ability to pack well with itself). The calculated solubility parameters for rosin esters are in the range of 8.8 – 9.1 (cal/cm3)½, which is very close to that of styrene. However because rosin ester structures are branched with fused rings (that reduce packing efficiency) they are able to tackify materials having solubility parameters ranging from δ = 8.0 (polyisobutylene) to δ = 9.4 (polyvinyl acetate). In contrast, pure monomer aromatic resins, which have a solubility parameter close to that of a rosin ester, have much more limited compatibility9. Because of their high solvency power rosin esters are often added as compatibilizing agents where polymers are marginally compatible with other synthetic resins. Rosin esters are soluble in aromatic and aliphatic hydrocarbons, most esters, ketones and halogenated solvents but insoluble in low molecular weight alcohols, glycols and water. For example, the room-temperature solubilities

Solubility Parameter, Solubility and Cloud Point – As stated above solubility parameter, δ, is one of the major factors that define the compatibility of a rosin ester with a given polymer, the others being molecular weight / molecular weight distribution and enthalpy (ability to pack well with itself). The calculated solubility parameters for rosin esters are in the range of 8.8 – 9.1 (cal/cm3)½, which is very close to that of styrene. However because rosin ester structures are branched with fused rings (that reduce packing efficiency) they are able to tackify materials having solubility parameters ranging from δ = 8.0 (polyisobutylene) to δ = 9.4 (polyvinyl acetate). In contrast, pure monomer aromatic resins, which have a solubility parameter close to that of a rosin ester, have much more limited compatibility9. Because of their high solvency power rosin esters are often added as compatibilizing agents where polymers are marginally compatible with other synthetic resins. Rosin esters are soluble in aromatic and aliphatic hydrocarbons, most esters, ketones and halogenated solvents but insoluble in low molecular weight alcohols, glycols and water. For example, the room-temperature solubilities

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Arizona Chemical Confidential – Do Not Copy

of a stabilized, tall oil rosin PE ester (Uni-Tac R100) in various solvents (20/80 wt/v %) are shown in Table 9.

of a stabilized, tall oil rosin PE ester (Uni-Tac R100) in various solvents (20/80 wt/v %) are shown in Table 9.

Table 9. Room-Temperature Solubility of a Stabilized TOR PE Ester Solubility Hydrogen Solvent Parameter Bonding Soluble Insoluble

Table 9. Room-Temperature Solubility of a Stabilized TOR PE Ester Solubility Hydrogen Solvent Parameter Bonding Soluble Insoluble

Mineral Spirits Hexane Heptane Cyclohexane Xylene Toluene Nitropropane Nitroethane Nitromethane Isopropyl Ether Diisobutyl Ketone Isobutyl Cellosolve Methyl Isobutyl Ketone Methyl n-Amyl Ketone n-Butyl Carbitol Ethyl Acetate Dibutyl Phthalate Carbitol Acetone Dimethyl Phthalate Dimethyl Sulfoxide Propylene Carbonate Ethyl Hexanol Cyclohexanol Isopropyl Alcohol Diethylene Glycol Ethyl Alcohol

Mineral Spirits Hexane Heptane Cyclohexane Xylene Toluene Nitropropane Nitroethane Nitromethane Isopropyl Ether Diisobutyl Ketone Isobutyl Cellosolve Methyl Isobutyl Ketone Methyl n-Amyl Ketone n-Butyl Carbitol Ethyl Acetate Dibutyl Phthalate Carbitol Acetone Dimethyl Phthalate Dimethyl Sulfoxide Propylene Carbonate Ethyl Hexanol Cyclohexanol Isopropyl Alcohol Diethylene Glycol Ethyl Alcohol

6.9 7.3 7.4 8.2 8.8 8.9 9.9 11.1 12.7 6.9 7.8 8.3 8.4 8.5 8.9 9.1 9.3 9.6 10.0 10.2 12.0 13.3 9.5 11.5 11.5 12.1 13.1

2.2 2.1 2.2 2.2 3.0 3.0 3.1 3.1 2.5 5.5 5.2 5.5 5.0 5.5 6.9 5.2 7.0 6.9 5.7 5.5 5.5 5.5 8.5 8.9 8.9 8.5 8.9

√ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √

6.9 7.3 7.4 8.2 8.8 8.9 9.9 11.1 12.7 6.9 7.8 8.3 8.4 8.5 8.9 9.1 9.3 9.6 10.0 10.2 12.0 13.3 9.5 11.5 11.5 12.1 13.1

2.2 2.1 2.2 2.2 3.0 3.0 3.1 3.1 2.5 5.5 5.2 5.5 5.0 5.5 6.9 5.2 7.0 6.9 5.7 5.5 5.5 5.5 8.5 8.9 8.9 8.5 8.9

√ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √

Another means of predicting compatibilities of resins and polymers is by determining cloud points in selected solvent systems. Cloud point data can be used to determine the degree of aliphatic / aromatic character as well as the polarity. Hercules developed this concept for tackifier resins using the cloud points in three solvent systems: MMAP (1 : 2 mixture of methylcyclohexane and aniline), DACP (1 : 1 mixture of xylene and diacetone alcohol) and OMSCP (odorless mineral spirits)10. The determination is straight forward and involves dissolving a standard amount of resin in the solvent at high temperature. The solution is allowed to cool and the temperature at which the resin begins to form a separate phase is the cloud point. The MMAP is a measure of aliphatic / aromatic character; OMSCP is a gauge of aliphatic character while DACP reflects the polarity. Note that the lower the cloud point, the more soluble the resin is in the solvent system. Some examples of rosin esters and other types of tackifier resins are shown in Table 10 below.

Another means of predicting compatibilities of resins and polymers is by determining cloud points in selected solvent systems. Cloud point data can be used to determine the degree of aliphatic / aromatic character as well as the polarity. Hercules developed this concept for tackifier resins using the cloud points in three solvent systems: MMAP (1 : 2 mixture of methylcyclohexane and aniline), DACP (1 : 1 mixture of xylene and diacetone alcohol) and OMSCP (odorless mineral spirits)10. The determination is straight forward and involves dissolving a standard amount of resin in the solvent at high temperature. The solution is allowed to cool and the temperature at which the resin begins to form a separate phase is the cloud point. The MMAP is a measure of aliphatic / aromatic character; OMSCP is a gauge of aliphatic character while DACP reflects the polarity. Note that the lower the cloud point, the more soluble the resin is in the solvent system. Some examples of rosin esters and other types of tackifier resins are shown in Table 10 below.

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Arizona Chemical Confidential – Do Not Copy

Table 10. Cloud Points of Selected Tackifiers Resin C5 Hydrocarbon Resin (95° SP) Rosin PE Ester (100° SP) Rosin Glycerin Ester (85° SP) Polymerized Rosin (85° SP)

MMAP 99 5 1 -15

Table 10. Cloud Points of Selected Tackifiers Cloud Points (°C) OMSP -77 -65 -45 -30

DACP 64 -55 -51 -51

Resin C5 Hydrocarbon Resin (95° SP) Rosin PE Ester (100° SP) Rosin Glycerin Ester (85° SP) Polymerized Rosin (85° SP)

MMAP 99 5 1 -15

Cloud Points (°C) OMSP -77 -65 -45 -30

DACP 64 -55 -51 -51

These data indicate that the C5 hydrocarbon resin is least aromatic, most aliphatic and least polar while polymerized rosin is most aromatic, least aliphatic and (like all rosin products) relatively polar. Rosin esters are approximately intermediate between hydrocarbon and polymerized resin properties. Thus hydrocarbons would be most compatible with aliphatic polymers while rosin derivatives are more compatible with polar and aromatic polymers. It is also possible to gauge resin compatibility by determining the cloud point in a polymer or polymer blend (e.g., resin compatibility in an EVA).

These data indicate that the C5 hydrocarbon resin is least aromatic, most aliphatic and least polar while polymerized rosin is most aromatic, least aliphatic and (like all rosin products) relatively polar. Rosin esters are approximately intermediate between hydrocarbon and polymerized resin properties. Thus hydrocarbons would be most compatible with aliphatic polymers while rosin derivatives are more compatible with polar and aromatic polymers. It is also possible to gauge resin compatibility by determining the cloud point in a polymer or polymer blend (e.g., resin compatibility in an EVA).

Hydroxyl Value – Because almost all rosin esters are made using an excess of polyol and

Hydroxyl Value – Because almost all rosin esters are made using an excess of polyol and

because the carboxyl group is hindered, there are usually hydroxyl groups present in the ester (e.g., exemplified by di- and triesters of PE). Steric hindrance makes the typical methods for determining rosin ester hydroxyl values inaccurate. However the hydroxyl value may be estimated by applying the equations in Table 11 to the amounts of mono- di- and triester present by GPC.

because the carboxyl group is hindered, there are usually hydroxyl groups present in the ester (e.g., exemplified by di- and triesters of PE). Steric hindrance makes the typical methods for determining rosin ester hydroxyl values inaccurate. However the hydroxyl value may be estimated by applying the equations in Table 11 to the amounts of mono- di- and triester present by GPC.

Table 11. Hydroxyl Number Equations Ester Hydroxyl Number (Calc.) Pentaerythritol ((% monoester x 399) + (% diester x 160) + (% triester x 57))/100 Glycerin ((% monoester x 300) + (% diester x 85.5))/100 Trimethylolpropane ((% monoester x 213) + (% diester x 80.4))/100 Triethylene glycol (% monoester x 129.9)/100

Table 11. Hydroxyl Number Equations Ester Hydroxyl Number (Calc.) Pentaerythritol ((% monoester x 399) + (% diester x 160) + (% triester x 57))/100 Glycerin ((% monoester x 300) + (% diester x 85.5))/100 Trimethylolpropane ((% monoester x 213) + (% diester x 80.4))/100 Triethylene glycol (% monoester x 129.9)/100

For example a PE ester containing 0.5% monoester, 5% diester and 30% triester would have a calculated hydroxyl value of 27 (note that the tetraester does not contribute an –OH group).

For example a PE ester containing 0.5% monoester, 5% diester and 30% triester would have a calculated hydroxyl value of 27 (note that the tetraester does not contribute an –OH group).

Calculated hydroxyl value = ((0.5 x 399) + (5 x 160) + (30 x 57))/100 = 27

Calculated hydroxyl value = ((0.5 x 399) + (5 x 160) + (30 x 57))/100 = 27

Iodine Value and Bromine Number – These analyses, originally developed for fatty

Iodine Value and Bromine Number – These analyses, originally developed for fatty

acids, are measures of the degree of unsaturation. The principle behind the analysis is that the amount of halogen that adds to the double bonds is a quantitative determination of the unsaturation of the sample. Because rosin has tertiary hydrogens that are easily replaced by halogen in a substitution reaction, this methodology has little significance. While bromine has been considered for analysis of rosin and rosin-containing materials because it is less reactive than iodine, bromine number is not a reliable value. For example abietic acid has a theoretical bromine number of 106, assuming only addition, but is reported to have a bromine number of 160. This corresponds to 6 bromines consumed; presumably 4 by addition, 1 by substitution and

acids, are measures of the degree of unsaturation. The principle behind the analysis is that the amount of halogen that adds to the double bonds is a quantitative determination of the unsaturation of the sample. Because rosin has tertiary hydrogens that are easily replaced by halogen in a substitution reaction, this methodology has little significance. While bromine has been considered for analysis of rosin and rosin-containing materials because it is less reactive than iodine, bromine number is not a reliable value. For example abietic acid has a theoretical bromine number of 106, assuming only addition, but is reported to have a bromine number of 160. This corresponds to 6 bromines consumed; presumably 4 by addition, 1 by substitution and

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Arizona Chemical Confidential – Do Not Copy

1 by forming HBr. The best method for determining unsaturation is by gas chromatographic identification of the specific rosin acids.

1 by forming HBr. The best method for determining unsaturation is by gas chromatographic identification of the specific rosin acids.

Stability – This term can encompass a variety of issues. Typically it refers to shelf life (the

Stability – This term can encompass a variety of issues. Typically it refers to shelf life (the

time period a resin can be stored at ambient conditions and still be in specification). But it can also refer to resin color stability (color retention under a given set of conditions), to hot melt stability (retention of hot-melt adhesive properties) or to other end-use properties. This discussion will concern only shelf life. Flaked rosin esters will oxidize (refer to the Oxidation section in Chapter 2) under ambient conditions resulting in an increase in polarity and, upon melting, color degradation and foaming. Liquid resins usually have long shelf lives because of low surface to volume ratios and because they are sealed in drums. Shelf life can be determined by real-time or by accelerated aging tests. One method for accelerated aging of flaked resins is carried out by placing sieved flakes in a paper bag in an incubator oven set at about 93°F/34°C and the re-melt color is measured periodically until it is out of specification. Color is usually the only property measured because its degradation is representative of other properties (e.g., peroxide number, foaming and reduced solubility in non-polar solvents). If this is compared with a standard rosin ester like Sylvalite RE 100L which has a shelf life of about three months at “ambient” (~ 80°F) conditions, one can approximate the shelf life of the subject resin. Since color loss increases exponentially with storage temperature, prolonged storage conditions above 100°F are unacceptable for most rosin esters. An example of the impact of time and temperature on color loss of a typical PE ester is shown in APPENDIX V. In this example, the rate of color loss doubles with each 7 - 8°F increase in temperature.

time period a resin can be stored at ambient conditions and still be in specification). But it can also refer to resin color stability (color retention under a given set of conditions), to hot melt stability (retention of hot-melt adhesive properties) or to other end-use properties. This discussion will concern only shelf life. Flaked rosin esters will oxidize (refer to the Oxidation section in Chapter 2) under ambient conditions resulting in an increase in polarity and, upon melting, color degradation and foaming. Liquid resins usually have long shelf lives because of low surface to volume ratios and because they are sealed in drums. Shelf life can be determined by real-time or by accelerated aging tests. One method for accelerated aging of flaked resins is carried out by placing sieved flakes in a paper bag in an incubator oven set at about 93°F/34°C and the re-melt color is measured periodically until it is out of specification. Color is usually the only property measured because its degradation is representative of other properties (e.g., peroxide number, foaming and reduced solubility in non-polar solvents). If this is compared with a standard rosin ester like Sylvalite RE 100L which has a shelf life of about three months at “ambient” (~ 80°F) conditions, one can approximate the shelf life of the subject resin. Since color loss increases exponentially with storage temperature, prolonged storage conditions above 100°F are unacceptable for most rosin esters. An example of the impact of time and temperature on color loss of a typical PE ester is shown in APPENDIX V. In this example, the rate of color loss doubles with each 7 - 8°F increase in temperature.

The problem with establishing a defined shelf life is that different locations / customers have different storage conditions. As stated above, as the storage temperature (and humidity) increases, the shelf life of a rosin ester decreases. Additionally different types of rosin esters oxidize at different rates under the same conditions. Applying the Arrhenius equation, if one determines the rate of color loss at different temperatures the activation energy (Ea) and the integration factor (log A) can be determined. In this case Ea reflects the sensitivity to temperature change (the smaller Ea, the more susceptible the rate of color loss to temperature). This was done for several resins where Ea and log A were calculated from the data at two temperatures, 65°F and 93°F. Refer to Table 12:

The problem with establishing a defined shelf life is that different locations / customers have different storage conditions. As stated above, as the storage temperature (and humidity) increases, the shelf life of a rosin ester decreases. Additionally different types of rosin esters oxidize at different rates under the same conditions. Applying the Arrhenius equation, if one determines the rate of color loss at different temperatures the activation energy (Ea) and the integration factor (log A) can be determined. In this case Ea reflects the sensitivity to temperature change (the smaller Ea, the more susceptible the rate of color loss to temperature). This was done for several resins where Ea and log A were calculated from the data at two temperatures, 65°F and 93°F. Refer to Table 12:

Table 12. Rates of Color Loss Rate of Color Loss / Week Rosin Ester @ 65°F @ 93°F SL RE 80HP 0.014 0.18 SL RE 100XL 0.014 0.24 SR TP 96 0.06 1.20 SR TR B115 0.04 0.17 SR PR 295 0.07 0.36 SL RE 85L 0.09 0.47 ST RE 85 0.17 0.55 SR PR R85 0.19 0.39 SG RE 85K 0.31 0.44

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Ea 29172 32458 34218 16527 18705 18880 13411 8214 4000

log A 20.028 22.493 24.446 10.999 12.876 13.117 9.290 5.440 2.492

Arizona Chemical Confidential – Do Not Copy

Table 12. Rates of Color Loss Rate of Color Loss / Week Rosin Ester @ 65°F @ 93°F SL RE 80HP 0.014 0.18 SL RE 100XL 0.014 0.24 SR TP 96 0.06 1.20 SR TR B115 0.04 0.17 SR PR 295 0.07 0.36 SL RE 85L 0.09 0.47 ST RE 85 0.17 0.55 SR PR R85 0.19 0.39 SG RE 85K 0.31 0.44

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Ea 29172 32458 34218 16527 18705 18880 13411 8214 4000

log A 20.028 22.493 24.446 10.999 12.876 13.117 9.290 5.440 2.492

Arizona Chemical Confidential – Do Not Copy

Because the Ea and log A were determined from only two data points, their accuracy is limited. However, for the resins in the above table, the rate of Gardner color loss per week (k) at any temperature (T) can be estimated by using the following equation:

Because the Ea and log A were determined from only two data points, their accuracy is limited. However, for the resins in the above table, the rate of Gardner color loss per week (k) at any temperature (T) can be estimated by using the following equation:

k = 10-(Ea/4.576*T) +logA

k = 10-(Ea/4.576*T) +logA

Where k = rate of Gardner color loss/week, Ea and log A for the specified resin are taken from the table and T = temperature in °K. Note that °K = ((°F-32)/1.8) +273.

Where k = rate of Gardner color loss/week, Ea and log A for the specified resin are taken from the table and T = temperature in °K. Note that °K = ((°F-32)/1.8) +273.

Spectral Properties – These properties include UV, IR and NMR (both H1 and C13).

Spectral Properties – These properties include UV, IR and NMR (both H1 and C13).

Stabilized rosin esters have a strong UV absorbance in the region 230 – 285 nm with the maximum occurring at about 240 nm. IR spectra show major absorbances for C–O at 1050 and 1300 cm-1, for C=O at 1715-1745 cm-1 and COOH (for high AN esters) at 1680-1725 cm-1. H1 NMR is useful for determining the amount of aromaticity (dehydroabietic acid) in a rosin ester. See assignments in Table 13. C13 NMR can be used for polyol identification as discussed in that section. Table 13. Major H1 Chemical Shifts for Rosin Derivatives Chemical Shift (ppm) PE Ester Glycerin Ester 0.6 – 2.2 m m 4.0 – 4.2 s m 7.0 m m 11.5

Rosin Acids m m s

Stabilized rosin esters have a strong UV absorbance in the region 230 – 285 nm with the maximum occurring at about 240 nm. IR spectra show major absorbances for C–O at 1050 and 1300 cm-1, for C=O at 1715-1745 cm-1 and COOH (for high AN esters) at 1680-1725 cm-1. H1 NMR is useful for determining the amount of aromaticity (dehydroabietic acid) in a rosin ester. See assignments in Table 13. C13 NMR can be used for polyol identification as discussed in that section. Table 13. Major H1 Chemical Shifts for Rosin Derivatives Chemical Shift (ppm) PE Ester Glycerin Ester 0.6 – 2.2 m m 4.0 – 4.2 s m 7.0 m m 11.5

Rosin Acids m m s

s = singlet; m = multiplet

s = singlet; m = multiplet

Specific Gravity, Density – Rosin esters have specific gravities ranging from 1.02 to 1.11. Densities in both grams/cm3 and pounds/gallon of some typical solid and liquid rosin esters are shown in Table 14.

Specific Gravity, Density – Rosin esters have specific gravities ranging from 1.02 to 1.11. Densities in both grams/cm3 and pounds/gallon of some typical solid and liquid rosin esters are shown in Table 14.

Table 14. Rosin Ester Densities at ~ 25°C Resin Ester Sylvatac RE 100 Pentaerythritol Sylvatac 80N Glycerin Sylvalite RE 10L Triethylene Glycol

grams/cm3 1.095 1.080 1.076

pounds/gallon 9.06 9.01 8.98

Table 14. Rosin Ester Densities at ~ 25°C Resin Ester Sylvatac RE 100 Pentaerythritol Sylvatac 80N Glycerin Sylvalite RE 10L Triethylene Glycol

grams/cm3 1.095 1.080 1.076

pounds/gallon 9.06 9.01 8.98

Most rosin esters have densities greater than that of water (8.34 lb/gal) at temperatures where they are fluid enough to be pumped. For example pentaerythritol esters are denser than water at temperatures below 190°C; liquid esters, such as Sylvalite RE 10L, have densities greater than water below about 140°C. The weight/gallon of rosin esters decreases by a factor of about 0.005 lb/gal for each °C increase in temperature. Applying this information, rosin PE ester densities can be estimated by the following equation, where the density (ρ) is in lb/gal and the temperature (T) is in °C. ρ = - 0.005T + 9.22

Most rosin esters have densities greater than that of water (8.34 lb/gal) at temperatures where they are fluid enough to be pumped. For example pentaerythritol esters are denser than water at temperatures below 190°C; liquid esters, such as Sylvalite RE 10L, have densities greater than water below about 140°C. The weight/gallon of rosin esters decreases by a factor of about 0.005 lb/gal for each °C increase in temperature. Applying this information, rosin PE ester densities can be estimated by the following equation, where the density (ρ) is in lb/gal and the temperature (T) is in °C. ρ = - 0.005T + 9.22

However it is important to note that the bulk density of flaked resins at ambient temperatures is about 60% of the “solid” resin (i.e., not flaked).

However it is important to note that the bulk density of flaked resins at ambient temperatures is about 60% of the “solid” resin (i.e., not flaked).

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Arizona Chemical Confidential – Do Not Copy

Volatile Materials – Tackifiers of all types are used in hot melt adhesives, therefore the

Volatile Materials – Tackifiers of all types are used in hot melt adhesives, therefore the

Wt. Loss = (-2.604 + 0.016 x T)2

Wt. Loss = (-2.604 + 0.016 x T)2

The relationship is valid over a temperature range of 165 - 350°C. The standard deviations are ± 0.2% and 1.1% at 200°C and 350°C, respectively. The experimental data indicates that with higher softening point resins, the weight loss is largely a function of temperature. This is logical since the esters are non-volatile, are all stripped and have similar acid numbers.

The relationship is valid over a temperature range of 165 - 350°C. The standard deviations are ± 0.2% and 1.1% at 200°C and 350°C, respectively. The experimental data indicates that with higher softening point resins, the weight loss is largely a function of temperature. This is logical since the esters are non-volatile, are all stripped and have similar acid numbers.

A more commonly used test method is to place about 10 gm. of the resin in an aluminum weighting dish in a forced air oven at 177°C for 24 hours and determine the percentage weight loss; see Table 15 for some typical data. Comparing the two different weight loss methods it is readily apparent that the test conditions significantly affect the results.

A more commonly used test method is to place about 10 gm. of the resin in an aluminum weighting dish in a forced air oven at 177°C for 24 hours and determine the percentage weight loss; see Table 15 for some typical data. Comparing the two different weight loss methods it is readily apparent that the test conditions significantly affect the results.

amount of volatiles (weight loss) at elevated temperatures is of concern to adhesive manufacturers and users. A rosin ester’s weight loss is dependent upon the method used. For example using TGA (heating rate of 20°C/min.) the weight loss of “typical” rosin esters with softening points in the range of 80 – 105°C can be approximated by the equation below.

Table 15. Volatiles Levels of Selected Rosin Esters Volatiles Level (24 hr @ 177°C) Low (0.7 – 1.8 %) Typical (2.0 – 3.0 %) High (> 4 %)

Rosin Ester Glycerin Foral 85 ST 1085 -

Pentaerythritol ST RE 100LV ST 4216 ST 100NS

amount of volatiles (weight loss) at elevated temperatures is of concern to adhesive manufacturers and users. A rosin ester’s weight loss is dependent upon the method used. For example using TGA (heating rate of 20°C/min.) the weight loss of “typical” rosin esters with softening points in the range of 80 – 105°C can be approximated by the equation below.

Table 15. Volatiles Levels of Selected Rosin Esters Triethylene glycol SL RE 10L

Volatiles Level (24 hr @ 177°C) Low (0.7 – 1.8 %) Typical (2.0 – 3.0 %) High (> 4 %)

Rosin Ester Glycerin Foral 85 ST 1085 -

Pentaerythritol ST RE 100LV ST 4216 ST 100NS

Triethylene glycol SL RE 10L

In this test, a high level of volatiles is indicative of a low degree of vacuum-steam stripping and /or the presence of low-molecular weight materials. Pentaerythritol esters such as Sylvatac RE 100LV have low volatiles (1.7 – 2.9 %) while liquid esters like Sylvalite RE 10L have relatively high levels (9.4 %). Not surprisingly the level of volatiles correlates well with the percentage of rosin oils (lights) as determined by GPC as shown in APPENDIX VI for Sylvatac RE 100LV. However volatiles did not correlate well with the rosin acids concentration, probably because rosin is less volatile and harder to remove than the light oils.

In this test, a high level of volatiles is indicative of a low degree of vacuum-steam stripping and /or the presence of low-molecular weight materials. Pentaerythritol esters such as Sylvatac RE 100LV have low volatiles (1.7 – 2.9 %) while liquid esters like Sylvalite RE 10L have relatively high levels (9.4 %). Not surprisingly the level of volatiles correlates well with the percentage of rosin oils (lights) as determined by GPC as shown in APPENDIX VI for Sylvatac RE 100LV. However volatiles did not correlate well with the rosin acids concentration, probably because rosin is less volatile and harder to remove than the light oils.

There is some indication that the presence of volatiles in a rosin ester contribute to a decrease in color stability (color loss upon heating). Upon aging a PE ester for 24 hours at 180°C, the presence of 0.2 – 0.7 wt. % volatiles caused a color loss of 3.7 – 5.8 Gardner units, respectively.

There is some indication that the presence of volatiles in a rosin ester contribute to a decrease in color stability (color loss upon heating). Upon aging a PE ester for 24 hours at 180°C, the presence of 0.2 – 0.7 wt. % volatiles caused a color loss of 3.7 – 5.8 Gardner units, respectively.

There are reports that the level of volatiles in a rosin ester is directly related to its odor and at first glance this seems quite reasonable. However this is true in the broadest sense. Even when the most efficient stripping processes are applied, rosin ester odor continues to be an issue.

There are reports that the level of volatiles in a rosin ester is directly related to its odor and at first glance this seems quite reasonable. However this is true in the broadest sense. Even when the most efficient stripping processes are applied, rosin ester odor continues to be an issue.

Odor – This property of rosin esters is both complex and subjective. Some applications (e.g.,

Odor – This property of rosin esters is both complex and subjective. Some applications (e.g.,

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top tier, multipurpose adhesives for diaper construction) have very strict odor requirements, limiting the use of tall oil rosin esters. It has long been the case that the terpene-like odors of gum and wood rosin esters were thought to smell “better” than tall oil rosin esters. The odor of Arizona Chemical Confidential – Do Not Copy

top tier, multipurpose adhesives for diaper construction) have very strict odor requirements, limiting the use of tall oil rosin esters. It has long been the case that the terpene-like odors of gum and wood rosin esters were thought to smell “better” than tall oil rosin esters. The odor of Arizona Chemical Confidential – Do Not Copy

tall oil rosin derivatives has been described as sour, acrid, sulfur-like, etc. Additionally, tall oil rosin esters heat-aged in the presence of air had more intense odors than nonheat-aged samples with a burnt, smoky character becoming more pronounced. A tremendous amount of work has been done by both Arizona Chemical and Union Camp Chemical groups to characterize, as well as to find ways to mitigate, these odors.

tall oil rosin derivatives has been described as sour, acrid, sulfur-like, etc. Additionally, tall oil rosin esters heat-aged in the presence of air had more intense odors than nonheat-aged samples with a burnt, smoky character becoming more pronounced. A tremendous amount of work has been done by both Arizona Chemical and Union Camp Chemical groups to characterize, as well as to find ways to mitigate, these odors.

D. McMahon and L. Nielsen at Union Camp’s Princeton Technology Center carried out much of the analytical work on rosin ester odor characterization. There are over 50 chemical compounds in the headspace of rosin PE esters that can impact odor, at least 23 of them negatively. It was initially thought that sulfur species, introduced during the Kraft pulping process, were the sole source of tall oil rosin odor11. While volatile sulfur compounds are indeed present in tall oil rosin esters, they are not a good measure of odor preference12 as both hydrocarbon and oxygencontaining chemicals have been shown to be odor sources. Interestingly the use of the sulfurcontaining disproportionation agent, Vultac 2, does not contribute significantly to rosin ester odor. Some examples of chemical odor sources in tall oil rosin esters are shown in Table 16 below. Table 16. Odor Types and Chemical Sources in Tall Oil Rosin Esters Odor Notes Chemical Species Compounds

D. McMahon and L. Nielsen at Union Camp’s Princeton Technology Center carried out much of the analytical work on rosin ester odor characterization. There are over 50 chemical compounds in the headspace of rosin PE esters that can impact odor, at least 23 of them negatively. It was initially thought that sulfur species, introduced during the Kraft pulping process, were the sole source of tall oil rosin odor11. While volatile sulfur compounds are indeed present in tall oil rosin esters, they are not a good measure of odor preference12 as both hydrocarbon and oxygencontaining chemicals have been shown to be odor sources. Interestingly the use of the sulfurcontaining disproportionation agent, Vultac 2, does not contribute significantly to rosin ester odor. Some examples of chemical odor sources in tall oil rosin esters are shown in Table 16 below. Table 16. Odor Types and Chemical Sources in Tall Oil Rosin Esters Odor Notes Chemical Species Compounds

Sulfury Gasoline, kerosene Sour, sharp, acrid Skunk-like Burnt woody, smoky Old sneakers

Mercaptans, alkyl sulfides Hydrocarbons Short chain acids Unsaturated C3 – C5 aldehydes Alkyl substituted benzenes, phenolics Ketones, unsaturated C8 aldehydes

Dimethyldisulfide Cyclohexane, p-cymene, toluene Isobutyric acid, butyric acid 2-Pentenal, 2-methyl-2-propenal Ethyl cumene, guaiacols 2-Cyclohexen-1-one

Sulfury Gasoline, kerosene Sour, sharp, acrid Skunk-like Burnt woody, smoky Old sneakers

Mercaptans, alkyl sulfides Hydrocarbons Short chain acids Unsaturated C3 – C5 aldehydes Alkyl substituted benzenes, phenolics Ketones, unsaturated C8 aldehydes

Dimethyldisulfide Cyclohexane, p-cymene, toluene Isobutyric acid, butyric acid 2-Pentenal, 2-methyl-2-propenal Ethyl cumene, guaiacols 2-Cyclohexen-1-one

Numerous attempts have been made to remove tall oil rosin odor bodies. Some approaches taken include heat or chemical treatment followed by distillation, the use of absorbents like clays, carbons, zeolites as well metal adsorbents like nickel, copper, copper-zinc-aluminum oxide. These processes were both expensive and ineffective13.

Numerous attempts have been made to remove tall oil rosin odor bodies. Some approaches taken include heat or chemical treatment followed by distillation, the use of absorbents like clays, carbons, zeolites as well metal adsorbents like nickel, copper, copper-zinc-aluminum oxide. These processes were both expensive and ineffective13.

Tall oil rosin esters made from 1,8-octanediol and cyclohexanedimethylol (CHDM) have lower levels of odor compounds and are perceived to have lower odors than the corresponding PE esters. However headspace analyses showed that the odor compounds were the same for all tall oil rosin esters indicating their origin is in the rosin acid. Furthermore when the three aforementioned esters are heat-aged at 175°C for 72 hours their odor profiles become similar. They all end up with about the same number, type and intensity of odor compounds. An explanation for the low odor initially observed in the diol esters are their mild thermal histories during synthesis14.

Tall oil rosin esters made from 1,8-octanediol and cyclohexanedimethylol (CHDM) have lower levels of odor compounds and are perceived to have lower odors than the corresponding PE esters. However headspace analyses showed that the odor compounds were the same for all tall oil rosin esters indicating their origin is in the rosin acid. Furthermore when the three aforementioned esters are heat-aged at 175°C for 72 hours their odor profiles become similar. They all end up with about the same number, type and intensity of odor compounds. An explanation for the low odor initially observed in the diol esters are their mild thermal histories during synthesis14.

Three approaches have been somewhat successful in minimizing rosin ester odor: 1) malodor counteractants, 2) low-temperature, vacuum-steam deodorization and 3) stripping using a shortpath evaporator. Bush, Boake Allen, Inc., a fragrance house once owned by Union Camp Corp., was working on a malodor counteractant concept wherein certain molecules would block odor receptors in the nose thereby rendering some odors imperceptible. They applied this approach to rosin ester odor mitigation. BBA formulated the malodor counteractant “Fragrance 970584” and it was added to a rosin PE ester at about 300 ppm. This product (Sylvalite RE LO) was sold to Findley Adhesives for use in their nonwovens (diaper) adhesives for a few years but other than

Three approaches have been somewhat successful in minimizing rosin ester odor: 1) malodor counteractants, 2) low-temperature, vacuum-steam deodorization and 3) stripping using a shortpath evaporator. Bush, Boake Allen, Inc., a fragrance house once owned by Union Camp Corp., was working on a malodor counteractant concept wherein certain molecules would block odor receptors in the nose thereby rendering some odors imperceptible. They applied this approach to rosin ester odor mitigation. BBA formulated the malodor counteractant “Fragrance 970584” and it was added to a rosin PE ester at about 300 ppm. This product (Sylvalite RE LO) was sold to Findley Adhesives for use in their nonwovens (diaper) adhesives for a few years but other than

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Arizona Chemical Confidential – Do Not Copy

this one account this approach was not commercially accepted. The major issue was that the malodor counteractant was more of an odor mask than odor eliminator. Adhesive customers wanted a rosin ester with “no odor” not one with a different odor.

this one account this approach was not commercially accepted. The major issue was that the malodor counteractant was more of an odor mask than odor eliminator. Adhesive customers wanted a rosin ester with “no odor” not one with a different odor.

In 1994-95, work was carried out at Union Camp that led to a process to minimize odor in rosin ester commercial production and molten storage15. The observation that the odor of rosin esters is regenerated upon heating led to the following hypothesis: odor body formation is competitive with its removal by sparging at high temperatures, but at low temperatures, odor body removal is faster than formation. Thus if the vacuum-steam sparging step carried out at top reaction temperature in rosin ester production is also applied at a lower temperature (180°C is preferred but certainly below 200°C), the “odor bodies” could be minimized. This proved to be the case and the odor of rosin esters made using this process, while not eliminated, was much improved. This process currently is in use at Arizona’s US facilities and the resultant esters are suitable for use in second tier diaper adhesive manufacture. A similar approach was used to minimize odor regeneration during storage of molten rosin esters. It was demonstrated that if the molten ester is continually sparged with nitrogen the odor will remain constant or even improve slightly. With design engineering support from Union Camp, H.B. Fuller installed and used such a storage vessel at their Paducah, KY facility15.

In 1994-95, work was carried out at Union Camp that led to a process to minimize odor in rosin ester commercial production and molten storage15. The observation that the odor of rosin esters is regenerated upon heating led to the following hypothesis: odor body formation is competitive with its removal by sparging at high temperatures, but at low temperatures, odor body removal is faster than formation. Thus if the vacuum-steam sparging step carried out at top reaction temperature in rosin ester production is also applied at a lower temperature (180°C is preferred but certainly below 200°C), the “odor bodies” could be minimized. This proved to be the case and the odor of rosin esters made using this process, while not eliminated, was much improved. This process currently is in use at Arizona’s US facilities and the resultant esters are suitable for use in second tier diaper adhesive manufacture. A similar approach was used to minimize odor regeneration during storage of molten rosin esters. It was demonstrated that if the molten ester is continually sparged with nitrogen the odor will remain constant or even improve slightly. With design engineering support from Union Camp, H.B. Fuller installed and used such a storage vessel at their Paducah, KY facility15.

Arizona Chemical’s Scandinavian facilities prepare rosin esters by batch esterifying the rosin and polyol to an acid number of about 25 followed by vacuum stripping using a short-path evaporator. The evaporator conditions are about 0.5 – 2.0 mbar and 240 – 265°C at a flow rate of about 1000 lb/hr. This process is used because Scandinavian tall oil rosin contains heavy neutrals which result in rosin and rosin esters of decreased softening points. The use of the short-path evaporator allows the efficient removal of these materials thereby increasing the softening point of the resultant ester. This process is thought to remove more odor bodies than does vacuum steam sparging.

Arizona Chemical’s Scandinavian facilities prepare rosin esters by batch esterifying the rosin and polyol to an acid number of about 25 followed by vacuum stripping using a short-path evaporator. The evaporator conditions are about 0.5 – 2.0 mbar and 240 – 265°C at a flow rate of about 1000 lb/hr. This process is used because Scandinavian tall oil rosin contains heavy neutrals which result in rosin and rosin esters of decreased softening points. The use of the short-path evaporator allows the efficient removal of these materials thereby increasing the softening point of the resultant ester. This process is thought to remove more odor bodies than does vacuum steam sparging.

It is not clear whether the short-path or the low-temperature sparging process results in the lowest odor rosin esters as different odor panels have provided conflicting results. However the question may be academic as neither process produces tall oil rosin esters with low enough odors to be suitable for top-tier diaper construction adhesives.

It is not clear whether the short-path or the low-temperature sparging process results in the lowest odor rosin esters as different odor panels have provided conflicting results. However the question may be academic as neither process produces tall oil rosin esters with low enough odors to be suitable for top-tier diaper construction adhesives.

Thermal Properties – There is no published compilation of thermal property data on rosin

Thermal Properties – There is no published compilation of thermal property data on rosin

Vapor Pressure – The vapor pressures of rosin esters are relatively low due to their high molecular weights. Since the values are somewhat higher than expected for the esters, it is likely the vapor pressures are due to volatiles present in the ester. Some examples are shown in Table 17 (the value for Uni-Tac R40 appears low).

Vapor Pressure – The vapor pressures of rosin esters are relatively low due to their high molecular weights. Since the values are somewhat higher than expected for the esters, it is likely the vapor pressures are due to volatiles present in the ester. Some examples are shown in Table 17 (the value for Uni-Tac R40 appears low).

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esters and only a limited amount on rosin itself16. The rosin ester vapor pressure data were determined by an outside testing laboratory. While the heat capacity and thermal conductivity data are based on rosin, it is believed that they are suitable for rosin ester process design calculations.

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esters and only a limited amount on rosin itself16. The rosin ester vapor pressure data were determined by an outside testing laboratory. While the heat capacity and thermal conductivity data are based on rosin, it is believed that they are suitable for rosin ester process design calculations.

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Table 17. Rosin Ester Vapor Pressures Rosin Ester Ester Type Uni-Tac R40 PE/DEG Uni-Tac XL-10 TEG Sylvatac 4216 PE Sylvatac RE 80N Glycerin Uni-Tac R112 IPA/PE

Vapor Pressure (torr) @ 205°C 6 36 36 44 46

Table 17. Rosin Ester Vapor Pressures Rosin Ester Ester Type Uni-Tac R40 PE/DEG Uni-Tac XL-10 TEG Sylvatac 4216 PE Sylvatac RE 80N Glycerin Uni-Tac R112 IPA/PE

Vapor Pressure (torr) @ 205°C 6 36 36 44 46

Heat Capacity – This property, also called specific heat, is an important engineering value used for specifying commercial heating and cooling systems. Rosin ester heat capacity can be estimated from the following equation.

Heat Capacity – This property, also called specific heat, is an important engineering value used for specifying commercial heating and cooling systems. Rosin ester heat capacity can be estimated from the following equation.

Cp = 0.454e0.002T

Cp = 0.454e0.002T

Where Cp = the heat capacity in calories/gm·°C and T = temperature in °C. Typical values are shown below. 0.55 calories/gm·°C at 100°C 0.76 calories/gm·°C at 250°C

Where Cp = the heat capacity in calories/gm·°C and T = temperature in °C. Typical values are shown below. 0.55 calories/gm·°C at 100°C 0.76 calories/gm·°C at 250°C

Thermal Conductivity – Rosin and its derivatives are poor conductors of heat. The thermal conductivity of molten rosin acids and as an estimate, rosin esters, at various temperatures is shown below: 0.131 Kcal/hr·m·°C at 150°C 0.127 Kcal/hr·m·°C at 177°C 0.134 Kcal/hr·m·°C at 232°C

Thermal Conductivity – Rosin and its derivatives are poor conductors of heat. The thermal conductivity of molten rosin acids and as an estimate, rosin esters, at various temperatures is shown below: 0.131 Kcal/hr·m·°C at 150°C 0.127 Kcal/hr·m·°C at 177°C 0.134 Kcal/hr·m·°C at 232°C

Heat of Combustion – The heat of combustion for a dehydroabietic acid, pentaerythritol tetraester was calculated using the molar group contribution method of Walters17. A value of 39.3 kJ/Kg (16,884 BTU/lb) was obtained.

Heat of Combustion – The heat of combustion for a dehydroabietic acid, pentaerythritol tetraester was calculated using the molar group contribution method of Walters17. A value of 39.3 kJ/Kg (16,884 BTU/lb) was obtained.

Hazard Information – This section is a short compilation of information relating to fire and

Hazard Information – This section is a short compilation of information relating to fire and

dust explosion hazards. The information is general therefore Arizona’s Regulatory Group should be contacted for specific product information.

dust explosion hazards. The information is general therefore Arizona’s Regulatory Group should be contacted for specific product information.

Flash Point – The lowest temperature at which a substance will ignite in the presence of an external source of ignition is known as its flash point. The determinations shown in Table 18 below were made using Standard Test Methods for Flash Point by Pensky-Martens Closed Cup (ASTM D 93-99) and Seta-flash Closed-Cup method (ASTM D3828-87).

Flash Point – The lowest temperature at which a substance will ignite in the presence of an external source of ignition is known as its flash point. The determinations shown in Table 18 below were made using Standard Test Methods for Flash Point by Pensky-Martens Closed Cup (ASTM D 93-99) and Seta-flash Closed-Cup method (ASTM D3828-87).

Table 18. Rosin Ester Flash Points Ester Trade Name Sylvatac RE 40N Uni-Tac XL 10 Uni-Tac R40

Table 18. Rosin Ester Flash Points

Ester Type Glycerin TEG PE-DEG

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Flash Point (°C) Pensky-Martens Setaflash 188 188 204 210 221 227

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Ester Trade Name Sylvatac RE 40N Uni-Tac XL 10 Uni-Tac R40

Ester Type Glycerin TEG PE-DEG

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Flash Point (°C) Pensky-Martens Setaflash 188 188 204 210 221 227

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