Leather resistant

Commonly used repeUents for leather are sUicones, chrome complexes of long chain fatty acids, and fluorochemicals. Fluorochemical repeUents also provide repeUency to oUs and greases so that the treated leather resists staining. A water repeUent may also be a hydrophobic chemical insolubUized in the leather. A simple water-repeUent treatment consists of forming an aluminum soap in leather by the two-step process of applying a soap, and then an aluminum salt. 

Leather (qv) has been employed for many uses since ancient time on account of the convertibiUty of an easily decomposed substance into one which resists putrefaction. Leather is stUl an important material with its unique stmcture it is so dense in texture that it resists wind and water while retaining breathabihty and flexibiUty, which makes the resulting goods comfortable. Early attempts to imitate leather included appHcation of oil, mbber, or soluble cotton onto paper or fabrics. However, very Htde progress had been made until the era of synthetic resins began in the twentieth century. 

Such a unique hierarchical stmcture gives leather several advantages (/) transformabiUty into any desired shape, (2) resistance to penetration of wind, water, and other materials, (3) breathabiUty (water vapor and air permeabiUty, and water absorption), (4) flexibiUty, and (5) processibiUty into finished forms having a grain or suede surface. 

The properties of leather-like materials depend on the polymer used for substrate and coating layer. Feel, hand, and resistance to grain break are affected by the constmction. The polymers and constmctions of leather-like materials are shown in Table 1. Physical properties of leather and leather-like materials are shown in Table 2. 

Use of a shoe poHsh imparts high gloss, maintains the supple hand of the leather (qv), and increases the weather resistance of the leather (3,57—59). Three general types of poHshes are produced solvent pastes, self-polishing Hquids, and emulsion creams. Solvent pastes represent ca 60% of the market (58). 

Potassium forms corrosive potassium hydroxide and Hberates explosive hydrogen gas upon reaction with water and moisture. Airborne potassium dusts or potassium combustion products attack mucous membranes and skin causing bums and skin cauterization. Inhalation and skin contact must be avoided. Safety goggles, full face shields, respirators, leather gloves, fire-resistant clothing, and a leather apron are considered minimum safety equipment. 

The greatest industrial consumption of monobasic aluminum acetate has been as a solution in the preparation of red color lakes for the dyeing of cotton. Formation of a water-resistant coating on fabrics, paper, leather, or other materials is also an important appHcation. In this process, for example, cloth is dipped into a solution of water-soluble soap, then into the aluminum salt solution, forming an insoluble, water-resistant aluminum soap coating on the fiber surfaces (10). 

Chrome complexes of stearic and myristic acids provide water and aqueous stain resistance, dimensional stabUity, and lubricity. The products may also enhance the appearance and durabUity of leather. The chrome complex reacts with the leather molecules to form a permanent bond. 

For dynamic water resistance, the Maeser Test, ASTM D2099 (53) measures the number of flexes and water penetration. The flex imparted to the leather is a magnification of the flex given the vamp of a shoe ia actual wear. 

Chlorinated paraffins are versatile materials and are used in widely differing appHcations. As cost-effective plasticizers, they are employed in plastics particularly PVC, mbbers, surface coatings, adhesives, and sealants. Where required they impart the additional features of fire retardance, and chemical and water resistance. In conjunction with antimony trioxide, they constitute one of the most cost-effective fire-retardant systems for polymeric materials, textiles, surface coatings, and paper products. Chlorinated paraffins are also employed as components in fat Hquors used in the leather industry, as extreme pressure additives in metal-working lubricants, and as solvents in carbonless copying paper. 

Leather 220 Low cost. Limited cbemical and beat resistance. Not recommended against pressurized steam, acid or alkali solutions. 

Leather To 210 Good mechanical properties for sealing. Resistant to alcohol, gasobne, many oils and solvents, synthetic hydraulic fluids, water. 

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