| 摘要 |
1,251,507. Polyamide precursors for polyimides. KALLE A.G. 8 Nov., 1968 [11 Nov., 1967], No. 52974/68. Heading C3R. Polyamides curable to polyimides are obtained by reacting an anhydride of a tri- or tetra-carboxylic acid anhydride in an inert organic solvent with one mole of an aliphatic and/or aromatic monohydroxy compound per equivalent of carboxylic anhydride to half esterify the anhydride group or groups and converting the product to the polyamide by reaction with 1 to 1.3 mols of a diisocyanate. Up to 30 mol. per cent of the partial ester may be replaced by an unesterified dicarboxylic acid e.g. isophthalic. Specified anhydrides are pyromellitic dianhydride, benzophenone-3,3<SP>1</SP>,4,4<SP>1</SP>- tetracarboxylic dianhydride, naphthalene- 1,4,5,8 - tetracarboxylic dianhydride and trimellitic monoanhydride; mono-hydroxy compounds C 1-4 alkanols, phenol, 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol, 2{2-(2- methoxyethoxy)ethoxy}ethanol and p-methoxyphenol; solvents dimethyl formamide, acetamide or sulphoxide; diisocyanates diphenyl - methane or -ether - 4,4<SP>1</SP> - diisocyanate and hexamethylene diisocyanate; and catalysts 0.1 to 2% by weight of the isocyanate of a tamine or Cu, Co or Pb naphthenate. The solutions of the polyamide may be used to give films or coatings, e.g. for packaging or electrical or thermal insulation, and are convertible to polyimides above 150‹ C. Other polymers, plasticizers, fillers, dyestuffs or pigments may be included. In Examples 1 to 3 polyamide solutions of R.V. (at 1% in m-cresol at 25‹ C.) 1À14, 1.37 and 1.4 respectively are obtained from thediester of benzophenone dianhydride and diphenylmethane diisocyanate in dimethylformamide; in Example 2 1,4-diaza-{2,2,2}- bicyclooctane is used as catalyst and in Example 3 20 mol. per cent of the diester is replaced by isophthalic acid. In Example 4 polyamide of R.V. 1.0 is obtained from the p-methoxyphenyl monoester of trimellitic anhydride and diphenyl methane diisocyanate. |
