| 摘要 |
1,150,758. Curing epoxy resins. CIBA Ltd. 1 Dec., 1966 [10 Dec., 1965; 26 Sept., 1966], No. 53884/66. Heading C3B. Epoxy resins are cured using polycarboxylic acid anhydrides which consist, at least partially, of a mixture of anhydrides obtained by isomerizing a methyl-tetrahydrophthalic anhydride. Isomerization may take place at elevated temperature (e.g. 8 hours at 210‹ C.) in the presence of a Pd or Ru catalyst. The starting material may be 4-methyl-#<SP>4</SP>-tetrahydrophthalic anhydride and the product may contain 30-45% by wt. of 4-methyl-#<SP>1</SP>-tetrahydrophthalic anhydride. A disproportionation reaction may also take place leading, e.g., to the formation of 15-35% by wt. of 4-methylhexahydrophthalic anhydride and from 7-18% by wt. of 4-methylphthalic anhydride. The curing catalyst may also comprise, subsequently added, hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride or 4-methyl-#<SP>4</SP>-tetrahydrophthalic anhydride. A tertiary amine or a sodium alcoholate may also be present as curing accelerator. |
