| 摘要 |
1,246,732. Polyurethane foams. STANDARD OIL CO. 22 April, 1969 [23 April, 1968], No. 20473/69. Headings C3C and C3R. Polyurethane foams are prepared by reacting in the presence of a substance capable of producing a gas within the reaction mixture, (1) a polyfunctional aromatic compound having at least two carbpnyl groups each attached to an aromatic nucleus, each carbonyl group being present as part of a carboxylic acid anhydride, carboxyl or acid halide group, (2) a liquid polyarylpolyisocyanate containing at least two interconnected aromatic rings and at least one isocyanate group per aromatic ring in an equivalent weight ratio of (2) to (1) of 0À6 1 to 4À0 : 1, and (3) a polyol component comprising a polyol adduct of M.W. less than 2000 and having at least 3 hydroxyl groups (including carboxylic hydroxyl groups) per molecule in an equivalent weight ratio of (3) to (1) plus (2) of 0À1 : 1 to 3À0 : 1, the polyol adduct being a half-ester reaction adduct of (a) a polyether polyol and (b) an anhydride of a polyfunctional carboxylic acid, from 5 to 40 weight per cent of the adduct being derived from the anhydride. The preferred polyfunctional aromatic compound (1) is trimellitic anhydride but other compounds, e.g. benzophenone tetracarboxylic acid di-anhydride and glycerol tris(4-trimellitate) may be used. Polymethylene polyphenylisocyanates having an average of 2À1 to 3À5 benzene rings per molecule are preferred polyisocyanates. The polyol component (3) is most suitably prepared from a sucrose-, sorbitol-, alpha-methylglucoside- or pentaerythritol-based polyether and tetrabromophthalic-, tetrachlorophthalic- or chlorendic-anhydride optionally in the presence of a polyethylene glycol. The foam may be prepared by the "one-shot" process or by reacting component (1) with component (2) to form a precursor which is reacted with the polyol component (3). Conventional blowing agents, catalyst, surfactants and flame-retarding agents may be incorporated in the reaction mixture. Half-ester adducts are described being prepared from propoxylated sucrose, pentaerythritol, trimethylolpropane, α-methyl glucoside or sorbitol, optionally mixed with a polyethylene glycol of low molecular weight and tetrabromophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, phthalic anhydride, trimellitic anhydride and chlorendic anhydride. |
