Rosin acids

Table 8. UOP Sorbex Separation of Fatty Acids from Rosin Acids in Distilled Tall Oil...

Fig. 3. Resin acids in rosin sizes, R = CH(CH2)2- The rosin acids are represented here as abietic acid [514-10-3] (1) and levopimaric acid [79-54-9] (2). In rosin there are other isomers and disproportionation products. The product of reaction with fumaric acid (3) is levopimaric acid— fumaric acid adduct...

Tall oil rosin is a by-product of paper manufacturing. Raw wood chips are digested under heat and pressure with a mixture of sodium hydroxide and sodium sulfide. Soluble sodium salts of lignin, rosin, and fatty acids are formed, which are removed from the wood pulp as a dark solution. The soaps of the rosin and fatty acids float to the top of the mixture, where they are skimmed off and treated with sulfuric acid to free the rosin and fatty acids. This mixture, known as cmde tall oil (CTO), is refined further to remove color and odor bodies fractional distillation separates the tall oil rosin acids from the fatty acids (see Tall oil). 

The most commonly used emulsifiers are sodium, potassium, or ammonium salts of oleic acid, stearic acid, or rosin acids, or disproportionate rosin acids, either singly or in mixture. An aLkylsulfate or aLkylarenesulfonate can also be used or be present as a stabilizer. A useful stabilizer of this class is the condensation product of formaldehyde with the sodium salt of P-naphthalenesulfonic acid. AH these primary emulsifiers and stabilizers are anionic and on adsorption they confer a negative charge to the polymer particles. Latices stabilized with cationic or nonionic surfactants have been developed for special apphcations. Despite the high concentration of emulsifiers in most synthetic latices, only a small proportion is present in the aqueous phase nearly all of it is adsorbed on the polymer particles. 

Eatty acid soap was first used for ESBR. Its scarcity prompted the investigation of rosin acids from gum and wood as substitutes (1). The discovery of the disproportionation of rosin allowed rosin acid soaps to overcome the polymerization inhibition of untreated rosin acids. Rosin acid soaps gave the added benefit of tack to the finished polymer. In the 1990s, both fatty acid and rosin acid soaps, mainly derived from tall oil, are used in ESBR. 

The principal constituents of rosin (qv) are abietic and related acids. Tall oil (qv) is a mixture of unsaturated fatty and aHcycHc acids of the abietic family. Refined tall oil may be high in rosin acids or unsaturated acids, depending on the refining process. Ethoxylates of rosin acids, eg, dehydro abietic acid, are similar to fatty acid ethoxylates in surfactant properties and manufacture, except for thek stabiHty to hydrolysis. No noticeable decomposition is observed when a rosin ester of this type is boiled for 15 min in 10% sulfuric acid or 25% sodium hydroxide (90). Steric hindrance of the carboxylate group associated with the aHcycHc moiety has been suggested as the cause of this unexpectedly great hydrolytic stabiHty. 

Tall oil fatty acids (TOFA) consist primarily of oleic andlinoleic acids and are obtained by the distillation of crude tall oil. Crude tall oil, a by-product of the kraft pulping process, is a mixture of fatty acids, rosin acids, and unsaponiftables (1). These components are separated from one another by a series of distillations (2). Several grades of TOFA are available depending on rosin, unsap oniftable content, color, and color stabiUty. Typical compositions of tall oil fatty acid products are shown in Table 1 (see Tall oil). 

Trees, especially conifers, contain tall oils. Tall oil is not isolated dkecfly tall oil fatty acids are isolated from the soaps generated as a by-product of the sulfate pulping process for making paper. Refined tall oil fatty acids are obtained by acidification of the soaps, followed by fractional distillation to separate the fatty acids from the rosin acids and terpene hydrocarbons that also are present in the cmde tall oil fatty acids (see Carboxylic acids Fatty ACIDS FROMTALL OIL). 

Compounding is quite different for the two systems. The solvent base system is dependent on magnesium oxide and a /-butylphenoHc resin in the formulation to provide specific adhesion, tack, and added strength. Neither of these materials have proven useful in latex adhesive formulations due to colloidal incompatibihty. In addition, 2inc oxide slowly reacts with carboxylated latexes and reduces their tack. Zinc oxide is an acceptable additive to anionic latex, however. Other tackifying resins, such as rosin acids and esters, must be used with anionic latexes to provide sufficient tack and open time. 

Latex Types. Latexes are differentiated both by the nature of the coUoidal system and by the type of polymer present. Nearly aU of the coUoidal systems are similar to those used in the manufacture of dry types. That is, they are anionic and contain either a sodium or potassium salt of a rosin acid or derivative. In addition, they may also contain a strong acid soap to provide additional stabUity. Those having polymer soUds around 60% contain a very finely tuned soap system to avoid excessive emulsion viscosity during polymeri2ation (162—164). Du Pont also offers a carboxylated nonionic latex stabili2ed with poly(vinyl alcohol). This latex type is especiaUy resistant to flocculation by electrolytes, heat, and mechanical shear, surviving conditions which would easUy flocculate ionic latexes. The differences between anionic and nonionic latexes are outlined in Table 11. 

Rosin and tall oil-based tackifiers are derived from feedstock, which is typically obtained by extraction and distillation of the materials from shredded tree stumps or wood chips. A typical structure of one of the different products obtained through this process is this abietic acid structure shown in Fig. 14 as a representative of the rosin acid family. 

Separation of fatty acids (Ruthven, 1997). Tall oil from the pulp and paper industry is subjected to separation of rosin acid, linoleic acid, oleic acid, and neutral compounds. Distillation at reduced pressure is u.sed, but this leads to degradation of products. A Sorbex process eliminates this problem. 

We focused our attention on Tall oil, a by-product of the paper industry, whenever this is prepared according to the KRAFT process. Said material consists of a mixture of highly unsaturated fatty acids (many of which with conjugated diene systems) and terpene derived rosin acids. The rosin acids have the molecular formula C20H30O2 and thus belong to the diterpenes (pimaric and abietic acids). Tall Oil has an iodine number equal to approximately 170 gl2/100 g. 

Naturally occurring rosins are derived from vegetable sources in the forms of exudates, i.e., gums. Rosin and rosin esters have found a number of applications within the rubber industry. Rosin acids are easily oxidised and thus it is more usual to find rosin presented to the rubber industry in a... 

Humphrey A catalytic process for hydrogenating rosin acids. 

Cleary, M.T., Kulprathipanja, S., and Neuzil, R.W. (1985) Process for separating fatty acids from rosin acids. U.S. Patent 4,522,761. 

During the kraft pulping process, the first step in making hundreds of paper products, crude tall oil is obtained from the alkaline material by acidifying it with sulfuric acid. The crude tall oil is then converted through dehydration, dry distillation, and finally the fractionation of the vaporized tall oil compounds. Fatty acids, rosin acids, and neutral materials make up tall oil. 

Examples of the fatty acids are oleic (c -9-octadecenoic) and linoleic (c ,c -9,12-octadecadienoic) acid. The major constituent of rosin acids is abietic acid. Uses of tall oil are tall oil rosin (31%, for paper size, protective coatings, adhesives, inks, and rubber), tall oil fatty acids (30%, in protective coatings, soaps, and inks), tall oil pitch (30%, in fuel, binders, coatings, rubber modifiers, asphalt, sizing, inks, and hardboard impregnation), and distilled tall oil (9%, in soaps, coatings, flotation, and board impregnation). 

In the process described here [50], the esterification reaction was carried out in the homogeneous phase and was followed by distillation under vacuum of the methyl esters obtained, allowing the removal of rosin acids as a bottom product. Hydrogenation of tall oil methyl esters obtained in this way gave the results reported in Table 10.6 and Figure 10.8. 

Preparation of Emulsions. An emulsion is a system in which one liquid is colloidally dispersed in another (see Emulsions). The general method for preparing an oil-in-water emulsion is to combine the oil with a compatible fatty acid, such as an oleic, stearic, or rosin acid, and separately mix a proportionate quantity of an alkali, such as potassium hydroxide, with the water. The alkali solution should then be rapidly stirred to develop as much shear as possible while the oil phase is added. Use of a homogenizer to force the resulting emulsion through a fine orifice under pressure further reduces its oil particle size. Liquid oleic acid is a convenient fatty acid to use in emulsions, as it is readily miscible with most oils. 

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