GB515000A - Improvements relating to the treatment of lac or shellac - Google Patents

Abstract

515,000. Treatment of lac ; coating-compositions. SUTER, A. F., JANSER, A., and SUTER, W. E. May 16, 1938, No. 14531. [Classes 1 (i) and 95] A method of producing partial or total dispersion of lac or shellac in water consists in mechanically disintegrating the lac in the presence of the water until the lac has assumed partly or wholly a colloidal particle size, while maintaining a temperature below the softening point of the lac, and facilitating the dispersion by including in the water a wetting or dispersing agent in amount not sufficient to exert an appreciable dissolving action. Specified wetting or dispersing agents are sulphonated castor oil, tri-ethanolamine-lauryl-sulphonate, sodiumnaphthalene-sulphonate, ammonium linoleate, #-amino-ethylol-ricinoleate, ammonia, triethanolamine, ammonium sulpho-ricinoleate, and' alkali salts of shellac, partly hydrolysed shellac, or the oxyacids of shellac, such as the #-amino-ethylol compound of hydrolysed lac, and these may be used in conjunction with auxiliary dispersing agents such as linseed-oilfatty acids, glyceryl-mono-acetate, oleyl alcohol and ricinoleyl alcohol. Protective colloids such as methyl cellulose, gelatin, gum tragacanth, agar-agar, alkali caseinates and alginates are sometimes added. Organic solvents that possess a selective solvent power for the soft resinous lac portion, such As benzene and its homologues and tetra-hydro-naphthalene, may be added. These are readily emulsified and greatly promote the dispersion of the lac. If desired, the lac may be prepared, for' dispersion by the present process, by first dissolving it completely in an organic solvent or in an alkali, and precipitating it in a jelled or flocculent condition by means of water or an acid. The dispersions may be incorporated in coatings, paints, adhesives and mouldable materials, and the method of producing the dispersions is useful in separating the lac into hard and soft lac fractions, as the soft lac resin portion tends to disperse first and to assume a smaller particle size than the hard lac resin portion; and may, in consequence, be easily separated by filtration, especially if the dispersion is treated with an organic solvent having a selective solvent power for the soft, lac resin fraction. Drying oils, stand oils' and phenolaldehyde resins may be added and jointly emulsified, or rubber latex may be added after completion of the dispersion. Fillers, such as kaolin, and pigments may be incorporated. Examples are given. Specification 496,124. is referred to.