| 摘要 |
<p>Lignin is intimately admixed with polyepoxides. The lignin must be in such a form that it has a solubility of at least 5% by weight in the polyepoxide. Suitable lignins are:-alkali lignin in the free or acid form, wood hydrolysis lignin (e.g. Rheinau), demethylated lignin, and various esters and ethers of lignin, e.g. lignin treated with benzyl chloride or diethyl sulphate. Polyepoxides specified are glycidyl ethers of glycerol, (di)ethylene glycol, resorcinol, 1,3,5-hydroxy benzene, 1,5-dihydroxy naphthalene, 2,2,5,5-tetrakis-(4-hydroxy phenyl) hexane, and bis-phenol A; and dicyclopentadiene dioxide. Various modifying agents are also added to either or both in varying quantities and in various orders:- (i) phthalic, hexahydrophthalic, dodecenyl succinic, methyl nadic, tetrachlorophthalic, pyromellitic and maleic acids or anhydrides; (ii) amines, e.g. N,N-dimethyl benzylamine, m-phenylene diamine, hydroxy ethylated diethylene triamine, (iii) aliphatic monocarboxylic acids, e.g. oleic, linoleic, linolenic, palmitic, stearic and tall oil; (iv) solvents, e.g. acetone, xylene, mono ethyl ether of ethylene glycol and allyl glycidyl ether; (v) fillers, e.g. clays, sand, wood flour, resin scrap, asbestos, TiO2, and wood, cotton or glass fibres; (vi) Co or Ca naphthenates, phosphoric acid, epoxidized oils, and urea-formaldehyde, polyamide or polysulphide resins. Uses: The main uses are as moulding powders, adhesives, coating compositions and laminates (see Group VIII).ALSO:Lignin is reacted with a polycarboxylic curing agent for polyepoxides to provide a reaction product containing residual carboxyl groups, and the reaction product is then reacted with the polyepoxide (see Group IV(a)). In Example 32 phthalic anhydride is reacted with oven-dry free alkali lignin for 1 hour at 140 DEG C.ALSO:In Example 21 a wood board is made from aspen wood flakes sprayed with an acetone solution of an epoxy resin and lignin. The acetone is evaporated and the wood flakes are pressed at 200 p.s.i. and 350 DEG F. for 15 minutes to form a solid board 0,5 inches thick.</p> |
