GB788806A - Compositions comprising polyepoxides and silicon-containing compounds, and cured products prepared therefrom - Google Patents

Abstract

A composition, which may be heated to form resinous products, comprises a polyepoxide and and an organo-silicon compound having in the molecule at least one hydrogen atom reactive with the epoxy group. The polyepoxide may be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic and may be substituted with other radicals, e.g. halogens, hydroxyl or ether groups. They may be monomeric or polymeric. A large number of examples is given. The preferred substances are those prepared from epichlorhydrin and a dihydric phenol in an alkaline medium, and polymers of unsaturated epoxy compounds such as allyl glycidyl ether. In the organo-silicon compounds, the reactive hydrogen atoms may be in groups which are directly attached to silicon or to organic radicals which are attached to silicon. Such groups are OH, NH2, NHR, CONH2, CONHR, COOH, C ­ CH and SH. The preferred compounds include silanols, siloxanols, hydroxyl-containing silanes containing two or more silicon atoms bonded together through divalent organic radicals, and partially esterified silicon-containing polyhydric alcohols; and many examples of these and other silicon compounds are given. Reaction between the two components is effected by heating to 50 DEG to 250 DEG C., generally at atmospheric pressure, with or without solvents. Accelerators such as tertiary amines, choline and BF3 dihydrate complexes may be added. The products contain free OH groups and range from viscous liquids to solids. They are soluble in various oils and solvents and are compatible with phenolaldehyde resins and with film-forming materials such as drying oils, cellulose esters and ethers, vinyl polymers and urea-formaldehyde resins. The products may be cured by reacting, at temperatures up to 350 DEG C., with alkaline compounds such as sodium and potassium hydroxides, phenoxides and methoxide, and amires; with acidic compounds, e.g. phthalic anhydride; with polyisocyanates; or methylol compounds, e.g. urea- or melamine resins. They may be used in adhesive or impregnating compositions, by dissolving in or mixing with solvents such as benzene, toluene, acetonitrile or crotonitrile, together with the curing agent. They may also be used for electrical pottings and castings. They may be reacted with monocarboxylic acids to form esters which are useful as plasticizers and coatings, or with polyethylenic monocarboxylic acids, or with polycarboxylic acids. In the examples the polyepoxide used is prepared by reacting bis-phenol with an excess of epichlorhydrin in alkaline medium and has a molecular weight of about 350 and an epoxy equivalency of 1.75. In (1) it is heated with diphenylsilanediol, and the reaction product is dissolved in an organic solvent, ureaformaldehyde resin is added, and cured films are prepared by baking the composition on tin panels. The reaction product is also dissolved in a mixture of "Cellosolve" (Registered Trade Mark) and xylene, a small amount of citric acid is added, and cured films are obtained by baking on a glass plate. Using lead 2-ethylhexoate as catalyst, the film is cured at room temperature. Related reaction products are produced by substituting ditolyl-, dixylyl-, phenyloctyl-, and di (trifluoromethylphenyl) silanediols for the one above; and increased reaction rates are obtained by the addition of 0.1 per cent choline. (2) The polyepoxide is heated with triphenylhydroxysilane, and a solution of the reaction product in a mixture of methyl "Cellosolve" and xylene containing ethylene diamine as catalyst is converted to cured films.. (3) The polyepoxide is heated with dimethyl-bis (p-phenylol) silane to give a product having the probable structure: <FORM:0788806/IV (a)/1> This is dissolved in a solvent as in (2) containing phthalic anhydride as curing agent, and converted to films. Dibutyl-, diphenyl- and dicyclohexyl-bis (p-phenylol) silane may be substituted for the one used. (4) The polyepoxide is heated with tetramethyl disiloxanediol-1,3, and the product treated as in (3). The siloxane diol may be submitted by tetraphenyldisiloxanediol-1,3, hexamethyltrisiloxanediol and tetramethoxydisiloxanediol. (5) A 50 per cent methyl "Cellosolve" solution of the reaction product of Example (1) is combined with a 10 per cent methyl ethyl ketone solution of a polyvinyl acetal resin to form solutions of varying proportions of resins which form baked and airdried films. (6) A vinyl chloride-acetate copolymer solution in methylethyl ketone and toluene is substituted for the acetal solution of the previous example. (7) A vinyl acetate homopolymer is substituted for the copolymer of the previous example. Specifications 737,142, 737,515, 737,614 and 760,309 are referred to.