Shellac Shellacs

Shellac. Shellac wheels are limited to a few appHcations where extreme coolness of cut is required and wheel life is immaterial. They are produced by mixing shellac [9000-59-3] and abrasive grain in a heated mixer, then rolling or shaping to the desired configuration. 

Shellac. Shellac is outstanding in that it is the only resin of animal origin. Shellac is a yellow, orange, or brown solid derived from lac, the secretion of the scale-like Kerria lacca insects that inhabit trees in areas of India and Thailand. To obtain the resin, twigs encrusted with the insect s secretion are cut down from the trees, the incrustation is removed from the twigs, coarsely... 

Shellac, Bleached, Wax-Free, occurs as an amorphous, light yellow, granular resin. It is obtained from lac, the resinous secretion of the insect Laccifer (Tachardia) lacca Kerr (Fam. Coccidae). Shellac, Bleached, Wax-Free, is obtained by the same process as that described in the monograph for Bleached Shellac, except that, in addition, wax is removed by filtration. Its solubility is the same as that of Bleached Shellac. Shellac, Bleached, Wax-Free, is usually dissolved in a suitable solvent for application to food products. 

Paint related material (including paint thinning or reducing compounds), 3, 3.1, 3.2, 3.3,8 Polish Printing ink, 3, 3.1, 3.2, 3.3 Shellac Shellac solution Stain Varnish Varnish drier, liquid Varnish drier, solid... 

Collective name for resins of plant or animal origin - the sole example of the latter that has attained technical importance is shellac (shellac wax). The plant natural resins are based on secretions exudates) of particular plants, mostly trees, from natural or artificial (cuts in the bark) injuries. These exudates normally occur in the form of sticky masses that harden in the air as a result of evaporation of volatile components and/or polymerization and oxidation reactions. 

Sandarac. Light yellow conifer resin consisting of a mixture of terpenoid resin acids, especially pimaric (80%), callitrolic (10%), and sandaricinic acids (10%). S. is obtained from the bark of the North African sandarac cypress [Tetraclinis articulata (Callitris quadri-va/vis)].Mp. 135-140 °C, soluble in many organic solvents and turpentine oil. S. is used in the manufacture of special paints, polishes, putty, dental cement, and as a substitute for shellac (shellac wax). 

Shellac (shellac wax). S. is a hard, tough resin (mp. 65-85 °C) obtained from secretions of the female lac insect (Kerria lacca, Coccideae). Chemically S. consists of esterified carboxylic acids, especially hy-droxy fatty acids (e. g., aleuritic acid), as well as the terpenoid shellolic acid C15H20O6, Mr 296.32, mp. 204-207 °C, [a] 3 +26° (CHCI3)). S. is used in coatings for foods, cosmetics, and pharmaceuticals. 

Rosin Rosin acrylate Rosin hydrolyzed collagen Rubber latex Sericin Shellac Shellac wax Sodium acrylate/vinyl alcohol copolymer Sodium carrageenan Sodium C8-16 isoalkylsuccinyl lactoglobulin sulfonate... 

V—Vitrified S—Silicate R—Rubber RF—Rubber reinforced B—Resinoid BF—Resinoid reinforced E—Shellac O—Oxychloride... 

Bond Type. Most bonded abrasive products are produced with either a vitreous (glass or ceramic) or a resinoid (usually phenoHc resin) bond. Bonding agents such as mbber, shellac, sodium siHcate, magnesium oxychloride, or metal are used for special appHcations. 

Articles of circular cross section may be made in iron paste molds. To keep the inner surface of the paste mold moist, it is coated with shellac or varnish and a mixture of charcoal and linseed oil is baked on. Hot iron molds ate used for ware of any shape, particularly for screw threading, multiple decoration, or raised lettering. 

Many older finishes can be removed with single solvents or blends of petroleum solvents and oxygenates. Varnish can be removed with mineral spirits, shellac can be stripped with alcohols, and lacquers can be removed with blends of acetates and alcohols (lacquer thinners). The removal mechanism is one of dissolving the coating, then washing the surface or wiping away the finish. This method is often used to reamalgamate or liquefy old finishes on antique items of furniture. 

As solvents, the amyl alcohols are intermediate between hydrocarbon and the more water-miscible lower alcohol and ketone solvents. Eor example, they are good solvents and diluents for lacquers, hydrolytic fluids, dispersing agents in textile printing inks, industrial cleaning compounds, natural oils such as linseed and castor, synthetic resins such as alkyds, phenoHcs, urea —formaldehyde maleics, and adipates, and naturally occurring gums, such as shellac, paraffin waxes, rosin, and manila. In solvent mixtures they dissolve cellulose acetate, nitrocellulose, and ceUulosic ethers. 

Natural resins are generally described as solid or semisolid amorphous, fusible, organic substances that are formed in plant secretions. They are usually transparent or translucent yeUow-to-brown colored, and are soluble in organic solvents but not in water. The principal uses for natural resins are in varnishes, printing inks, adhesives, paper size, and polymer compositions. The term natural resins includes tree and plant exudates, fossil resins, mined resins, and shellac. They often have been altered from their original state during isolation and processing. For some appHcations, the resins have been chemically modified to increase their industrial utiUty. 

Unlike other natural resins, shellac [9000-59-3] is derived from the hardened secretion of the lac insect (species l ccifer (Tachardia) lacca Kerr (family Coccidae), also known as Kerns lacca (Kerr)). Shellac is a refined grade of the cmde lac secretion and is the most widely known lac product. Therefore, shellac has been accepted as the common generic term. Over 50% of the world s supply is produced in the Indian provinces of Bihar and Orissa, with the remainder originating in adjacent areas of southeast Asia such as Sri Lanka, China, Thailand, and Myanmar. 

Lac became an important component of decorative and protective finishes by the nineteenth century. It is ironic that the success of shellac led to the synthetic resin industry. Baekeland developed phenoHc resins while trying to find a substitute for shellac. 

Raw lac is first treated to remove water-soluble carbohydrates and the dye that gives lac its red color. Also removed are woody materials, insect bodies, and trash. It is further refined by either hot filtration or a solvent process. In the heat process, the dried, refined lac is filtered molten through cloth or wine screens to produce the standard grades of orange shellac. In the solvent process, lac is dissolved and refluxed in alcohol solvents, filtered to remove dirt and impurities, and concentrated by evaporation. The lac can be further decolori2ed in this process to produce very pale grades. Bleached shellac is prepared by treatment with dilute sodium hypochlorite and coalesced into slabs. 

Composition. Shellac is primarily a mixture of aUphatic polyhydroxy acids in the form of lactones and esters. It has an acid number of ca 70, a saponification number of ca 230, a hydroxyl number of ca 260, and an iodine number of ca 15. Its average molecular weight is ca 1000. Shellac is a complex mixture, but some of its constituents have been identified. Aleuritic acid, an optically inactive 9,10,16-trihydroxypalmitic acid, has been isolated by saponification. Related carboxyflc acids such as 16-hydroxy- and 9,10-dihydroxypalmitic acids, also have been identified after saponification. These acids may not be primary products of hydrolysis, but may have been produced by the treatment. Studies show that shellac contains carboxyflc acids with long methylene chains, unsaturated esters, probably an aliphatic aldehyde, a saturated aliphatic ester, a primary alcohol, and isolated or unconjugated double bonds. 

Uses. Synthetic resins have taken over a large share of the market for shellac. Unpigmented shellac is used on floors, woodwork, and paneling. 

White pigmented shellac is used as a primer—sealer for iaterior appHcations. Shellac is used as a protective coating for pharmaceuticals to maintain the potency of medication. Several coats of shellac gla2e protect medication from the effects of stomach acids so that the medication is not released before the tablet reaches the intestines. 

Candy is coated with shellac to seal in moisture and keep the product fresh. The coating provides a high gloss to the confection, which improves its appearance. Citms fmits and some apples are often coated with shellac. This improves the appearance, while allowing the fmit to breathe without spoilage. Shellac is used as a stiffener for felt hat bodies, primarily for recreational hats. It is also used to stiffen playing cards, providing "snap."... 

The poly(vinyl acetal) prepared from acetaldehyde was developed in the early 1940s by Shawinigan Chemicals, Ltd., of Canada and sold under the trade name Alvar. Early uses included injection-molded articles, coatings for paper and textiles, and replacement for shellac. Production peaked in the early 1950s and then decreased as a result of competition from less expensive resins such as poly(vinyl chloride) (see Vinyl polymers, poly(vinyl chloride)). 

Oxidized castor oils are excellent nonmigrating, nonvolatile plasticizers (qv) for ceUulosic resins, poly(vinyl butyral), polyamides, shellac, and natural and synthetic mbber (see Rubber, natural). The high viscosity products are also used as tackifiers in gasket compounds and adhesives (qv) because of good oil and solvent resistance. They also serve as excellent pigment grinding media and as a base for inks (qv), lubricating oils, and hydrauHc oils (62). 

Cyclohexanoae is miscible with methanol, ethanol, acetone, benzene, / -hexane, nitrobenzene, diethyl ether, naphtha, xylene, ethylene glycol, isoamyl acetate, diethylamine, and most organic solvents. This ketone dissolves cellulose nitrate, acetate, and ethers, vinyl resias, raw mbber, waxes, fats, shellac, basic dyes, oils, latex, bitumea, kaure, elemi, and many other organic compounds. 

One principal use of cyclohexanol has been in the manufacture of esters for use as plasticizers (qv), ie, cyclohexyl and dicyclohexyl phthalates. In the finishes industry, cyclohexanol is used as a solvent for lacquers, shellacs, and varnishes. Its low volatiUty helps to improve secondary flow and to prevent blushing. It also improves the miscibility of cellulose nitrate and resin solutions and helps maintain homogeneity during drying of lacquers. Reaction of cyclohexanol with ammonia produces cyclohexylamine [108-91-8], a corrosion inhibitor. Cyclohexanol is used as a stabilizer and homogenizer for soaps and synthetic detergent emulsions. It is used also by the textile industry as a dye solvent and kier-boiling assistant (see Dye carriers). 

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