Shellac applications

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

Until 1950 the principal application of shellac was in gramophone records. The resin acted as a binder for about three times its weight of mineral filter, e.g. slate... 

Chemical nature Isolation of casein from milk Production of casein plastics Properties of casein Applications Miscellaneous Protein Plastics Derivatives of Natural Rubber Gutta Percha and Related Materials Shellac... 

Thus, based on material applications, the following polymers are important natural rubber, coal, asphaltenes (bitumens), cellulose, chitin, starch, lignin, humus, shellac, amber, and certain proteins. Figure 4 shows the primary structures of some of the above polymers. For detailed information on their occurrence, conventional utilization, etc., refer to the references cited previously. 

Lacquer. A coating comprised of resins such as cellulose esters or ethers, shellac or gum, or allethyl alcohol that evaporates easily. The application process involves no chemical change, only the evaporation of the solvent leaving behind a hard, durable finish. 

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 yellow-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 applications, the resins have been chemically modified to increase their industrial utility. 

Shellac has had a commercial history similar to that of the traditional resins. It has been replaced by synthetic resins in many applications. In the 1950s, about 19,000 t of various grades of processed shellac were available in the United States. The volume was about 5,500 t in 1995. The largest importer of shellac is William Zinsser Company, Inc. The superior grades of shellac are sold for about 6.60— 9.90/kg, depending on quality. 

Shellac has been affirmed by the U.S. FDA (4) as GRAS for food applications. The most significant uses for shellac are in food, for coating fruits and confections to preserve quality and appearance. 

PVB combinations with the thermoplastic resins nitrocellulose or shellac have been used as sealers for wood finishing. In these applications the PVB component adds flexibility and adhesion. Tough, optically clear blends have been made with aliphatic polyurethanes. Thermosets are prepared with cross-linkers that form covalent bonds with hydroxy] groups. 

Disintegration time is measured at three steps in the process at compression, after application of the second shellac coat, and at finished product release. Table 4 compares the values of mean hardness obtained for 10 individual cores to the disintegration times for the core, shellacked core, and coated tablets. No... 

Natural products and transformed natural products can also be used as binding agents for packaging applications. These are shellac, dammar gum, dried unsaturated oils (linseed oil), rosin and hydrated esters of rosin, cellulose acetate and propionate acetate, cellulose acetobutyrate, cellulose nitrate and ethyl cellulose. 

Shellac, Bleached, occurs as an off white to tan, amorphous, granular resin. Shellac is obtained from lac, the resinous secretion of the insect Laccifer (Tachardia) lacca Kerr (Fam. Coc-cidae). Shellac, Bleached, is obtained by dissolving the lac in aqueous sodium carbonate, followed by bleaching with sodium hypochlorite, precipitation of the bleached lac with a dilute sulfuric acid solution, and drying. It is freely (though very slowly) soluble in alcohol, insoluble in water, and slightly soluble in acetone and in ether. Shellac, Bleached, is usually dissolved in a suitable solvent for application to food products. 

Bond Type. Alost bonded abrasive products are produced with either a vitreous (glass or ceramic) or a resinoid (usually7 phenolic resin) bond. Bonding agents such as rubber, shellac, sodium silicate, magnesium oxyvbloride, or metal are used for special applications. 

Shellac, Shellac wheels are limited to a few applications 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. 

Specht F, Saugestad M, Waaler T, Muller BW. The application of shellac acidic polymer for enteric coating. Pharm Technol Eur 1998 10(9) 20, 22, 24, 27, 28. 

Zein is used as a tablet binder in wet-granulation processes or as a tablet-coating agent mainly as a replacement for shellac. It is used primarily as an enteric-coating agent or in extended-release oral tablet formulations. Zein is also used in food applications as a coating agent. See Table I. 

Other special macromolecules are known, and some were analyzed by pyrolytic techniques. Among these are special gums and lacquers such as mastic, gum elemi, copal, kauri, sandarac, shellac, colophony, amber, etc. [4]. These materials have narrow fields of applications and were not included in this book. 

Stability of shellac to UV radiation is the most important optical property. The principal application of shellac was in gramophraie records. The resin acts as a binder for about three times its weight of mineral filler. Today, the most important application of shellac is in surface coatings. It is also used in some French polish as adhesives and cements including valve capping and optical cements. Shellac is also used in the manufacture of sealing wax. 

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