Patent GB-573826-A (GB)
Title: Manufacture of condensation products of lac and compositions made therewith
IPC: C09F5/08
Filed: 1943-09-28
Abstract: Lac which has been etherified with one of the hydroxyl groups of a glycol is esterified with a resin acid or with an unsaturated fatty acid containing more than one double bond, but containing no conjugated double bonds.  Two or more mixed resin acids or mixed fatty acids or a mixture of a resin acid with one or more fatty acids may be employed.  Suitable acids are abietic, e.g. as rosin, or the fatty acids of linseed, sunflower, perilla, soya bean or poppy seed oil.  Suitable glycols are ethylene, propylene, butylene or di-, tri- or tetra-ethylene glycol.  Etherification may be carried out with excess glycol above the melting point of the lac and, if desired, with an acid condensing agent such as aluminium chloride or sulphate or sulphuric or paratoluene sulphonic acid.  Excess glycol and condensing agent may be removed by washing with water or the glycol only may be removed by distillation and the residue with some remaining acid catalyst used for the esterification which may be conducted at 120-300 DEG  C. with or without a condensing agent, and if desired in an atmosphere of an inert gas, or in an inert solvent which is preferably an ingredient of the final composition.  The lac glycol ether may be polymerized before esterification.  Acidity of the products may be reduced by addition of a base, e.g. a metal oxide.  The products may be purified by treatment with a bleaching earth or activated carbon in the presence of solvents.  The products are soluble in drying oils which may be pre-bodied, or the lac ether-ester and the oil may be bodied together.  The ether-esters are compatible with synthetic resins such as formaldehyde condensation products of phenols, cresols, urea or melamine, or with cellulose esters or ethers.  They are suitable for paints, varnishes, linoleum, plasticizers, printers' ink, printers' blankets, electrical insulating coatings, or lacquers for tin plate for food containers. According to the examples: (1) the ethylene glycol ether of dewaxed lac is heated with linseed oil fatty acids at 140-150 DEG  C. in presence of p-toluene sulphonic acid or at 200 DEG  C. with no catalyst.  Solutions of the products in organic solvents yield air drying films which may be baked; (2) the butylene glycol ether of T.N. shellac is heated first with linseed oil fatty acids and then with rosin.  Litharge is dispersed in the product with heating and stirring and the product, thinned with white spirit yields an air-drying varnish; (3) an ethylene glycol ether of shellac is esterified with fatty acid from linseed, sunflower, perilla, soya bean or poppy seed oil or a mixture of these acids.  The product is heated with linseed oil and thinned with white spirit.  It yields air-drying films which may be baked.  Pale bodied oil, dehydrated castor oil or tung oil may replace the linseed oil, or a bodied oil such as stand oil may be used without the second heating treatment; (4) ethylene glycol ether of orange shellac is heated with rosin and slaked lime or zinc oxide mixed with the product which is soluble in hydrocarbons or drying oils to yield air-drying or stoving media; (5) Dewaxed lac is melted with ethylene glycol, cooled, mixed with a little sulphuric acid, and the mixture distilled. Linseed oil fatty acids are added to the residue and the mixture heated with additional sulphuric acid.  The product may be thinned with white spirit to yield a varnish or bodied by further heating in an inert atmosphere; (6) ethylene glycol ether of shellac and rosin are melted together and white spirit added.  The product is refluxed, water being separated from the condensed solvent.  The resulting varnish may be further diluted with xylene or a xylene-white spirit mixture.  Other solvents which may be employed are tetralin, decalin or kerosene.