Leather fatliquoring

Uses Emulsifier for agric., emulsion polymerization, leather fatliquoring, paints Regulatory Exempt from tolerance under EPA 40CFR 180.1001 (c)(e)... 

Uses Emulsifier for agric. emulsions, emulsion polymerization, inverse emulsion polymerization, paints, leather fatliquoring Features Forms stable w/o emulsions Properties HLB 9.5 cloud pt. < 20 C (1% aq.)... 

Uses Solubilizer for acid cleaners, textile finishing oils, dry cleaning soaps, inks, lacquers, paints, metalworking fluids, pesticides, cosmetic emulsions, emulsion polymerization, leather fatliquoring Features Solubilizes water into aliphatic soivs. 

There are other drawbacks to conventionally fatliquored leather. When it is used in automobile upholstery, it is often heated by sunlight in the unstirred air of the parked vehicle to temperatures high enough to sublime or distill the fat or oil onto the windows. This deposited material is troublesome to remove and causes some lots of leather to be rejected by the automobile manufacmrer. Another drawback is flammability, which can be obviated by a judicious choice of oil in the emulsion. Further, the oil sometimes tends to migrate to the surface of the leather, causing an unpleasant film, or spew, to form. Under some conditions it can cause separation of the hnish or coating from the leather substratum. 

The emulsion of a fatliquor should not be too stable. The leathermaker wants to control its depth of penetration into the leather by the tendency of the surfactant to adsorb to the protein of the hide. This adsorption depletes the micelles of surfactant, causing the emulsion to break before it permeates the interior of the hide, releasing the oil somewhat superficially. The untreated interior thereby retains its stiffness, but with only a small mechanical moment. The product is then firm but resilient (not like cardboard). The released oil, with the surfactant tightly bound to the fibers, also resists being washed out of the leather by water. Suede leather, on the other hand, requires full penetration of the fatliquor and, therefore, an emulsifier that does not bind tightly to the protein. 

Figure 1. Effect of fatliquor on the structure of fibers in leather after drying. (Top) The 100- m fiber bundles In the leather dried without fatliquor are intact. (Bottom) They are broken into fragments when dried with fatliquor, making the leather compliant. Bar W im.

Egg yolk was once commonly used, probably because of its lecithin, to emulsify oils in leathermaking. Lecithin itself is effective as a fatliquor emulsifier (12). Nonionic emulsifiers have the advantage of forming emulsions that are stable to electrolytes, so they do not interact electrostatically with the chromium or aluminum tanning ions. Nonionic-anionic combinations (e.g., 1% nonionic-99% anionic) are now used to suppress the accumulation of fatty deposits or extrusions at the surface of the leather. These systems are under active development. 

Cationic surfactants are used mainly to treat the surface of the leather, making it waxy. These are typically C-16 to C-18 alkylbenzyl quaternary ammonium compounds (e.g., 13). Also effective are cationic fatliquors from aminated and quater-nized castor oil other vegetable oils are also used (14). 

Leather is also softened, after it is dried, by the addition of grease at temperatures at which it is fluid. These stuffing compounds are made from wool grease or high-melting (230-266°C, 110-130°F) mixmres of mineral waxes and fatty acids. For reasons that are not understood, they must be used at much higher levels than fatliquors— usually about 30% of the weight of the leather, instead of 10-15%. 

Examples of such developments are sulfation of transesterified rapeseed oil phosphatides (17) and the use of bicontinuous microemulsions obtained by the addition of aliphatic alcohols (18, 19). The stability of these systems promises to be more reliable than those in present use. Oils from wood (tall oil) can be sulfo-nated for self-emulsifying fatliquors (20). Polymerizable oils have been used in fatliquors (21). We expect more progress on the use of high polymers, such as the already commercial alkyl acrylate esters developed by Hodder et al. (22-24), and material based on elastomers (6). We anticipate the development of novel systems to be encouraged by the demand for leather in washable garments and automobile upholstery. 

The amount of residual namral fat and added fatliquor is usually determined by chemically analyzing hexane extracts, following ASTM Standard D-3495 (25). The leather is extracted in a Soxhlet apparatus and the amount dissolved in the hexane is determined gravimetric ally. Analyses for specific fatty components are described in (26). 

Fatliquor affects mostly the mechanical properties, measured also by a collection of ASTM methods given in (25). In addition, the sounds emitted by leather when it is deformed are greatly suppressed by the presence of fat, supporting a method of assay by means of the acoustic emission test (27). 

CrestoiL [Reilly-Whiteman] Emulsifier, fatliquoring agent for textile and leather industries. 

Dermoblock. [Alzo] Fatliquoring agents for leather, fin ptooessitig. 

Grairifat [Reilly-Whiteman] Sulfated fatliquors for leather industry. 

Monosulf. [Henkd/O anic Plods.] Sul-fated castnr oil penetrant emulsifier, dyeing assistant fatliquor, plasticizer for textiles, leathers, paper coatings, glues, latex. 

Atlasol 103 EINECS 2055655 Sodium decyl sulfate Sodium decyl sulphate Sulfuric acid, decyl ester, sodium salt. Emulsifier, wetting agent, dispersant, fiber lubricant, synthetic fatliquor for textile, leather, and general industrial applications. Atlas Chemical Corp. 

Properties Fixed pale yel. oily liq. peculiar odor sol. in alcohol, ether, chloroform, kerosene insol. in water dens. 0.916 solid, pt. -10 to 0 C iodine no. 70 sapon. no. 194-199 flash pt. 243 C Toxicology TSCA listed Precaution Combustible subject to spontaneous heating Uses Fatliquor and softener for leathers lubricant oiling wool emollient, solvent in cosmetics... 

Uses Lubricant, emulsifier textile applies. fatliquor, softener for leather processing... 

Uses Lubricant, emulsifier, carrier, base for fatliquor systems emulsifier, carrier for refined oils detergent formulations rust preventative metal polishes metalworking compds. penetrant, fiber lubricant for textile and leather processing... 

Neatsfoot oil Sodium decyl sulfate fatliquor, textiles Sodium decyl sulfate fat-liquoring agent, leather Canola oil Paraffin, chlorinated Rapeseed (Brassica campestris) oil fats/oils, edible Hydrogenated menhaden oil fatting agent, cosmetics Dimethicone copolyol acetate 2-Hexyldecyl stearate... 

According to the final product, leather requires a certain softness, which is achieved by application of fat. A fat content of 5% is essential gloves, garments, and upholstery may contain up to 15%. Therefore, after dyeing, the leather is oiled. In this process, called fatliquoring, oily fat is emulsified and applied to the leather in a warm bath. The emulsion breaks on contact with the chrome-tanned fibers of the leather, and the fat remains on the leather. The oils used are sulfated or sulfonated plant, animal or fish oils or synthetic products, usually biocide preserved (Heidemann 1990 Podmore 1995 Thorstensen 1995). 

The colored and fatliquored leather is dried, staked, and buffered. Staking and buffering are mechanical treatments to increase flexibility and softness and to achieve special surface aspects. 

The grafted leathers were analyzed and compared with controls (untreated leather). Ash, Kjeldahl nitrogen and ethyl acetate extractables were determined on a dry weight basis. Total polymer uptake was determined from increase of non-nitro organic solids as compared with that of controls. Homopolymer was determined from increase in extractables which were negligible in the controls, since the leather had not been fatliquored. 

Ivanov, A. M. Ivanov, I. A. Method of production of black dyeing composition for fatliquoring substances used in leather manufacturing. Russ. RU 2263713, 2005 Chem. Abstr. 2005, 143, 442411. 

---