Latent, heat-curable epoxy resin compositions containing metal carboxylate curing systems
AssigneeHenkel Research Corporation
InventorThomas J. Stierman
Life of this patent
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Abstract
Latent, heat-curable epoxy resin compositions containing metal carboxylate curing systems provide exceptional latency, particularly at elevated temperature, as well as facile curing, high T.sub.g and adhesive strength, and other attractive properties. The metal carboxylates comprise alkali metals and alkaline earth metals, aromatic and aliphatic metal carboxylates. The preferred curing systems comprise synergistic combinations of the metal carboxylates with cure modifiers.
Claims51
A heat-curable epoxy resin composition free of cure-effective amounts of an amine, carboxylic anhydride, or carboxylic acid in the acid form, comprising:
- (a) at least one polyepoxide;
- (b) from about 0.1 to about 50 parts of a metal carboxylate salt curing agent per hundred parts by weight of total epoxy resin, said metal carboxylate salt being selected from a Group IA or Group IIA metal and being derived from a carboxylic acid containing from 1 to 4 carboxyl groups, wherein said metal carboxylate salt is substantially soluble in said epoxy resin composition at a cure temperature of above about 100.degree. C.;
- and
- (c) from about 1 to about 100 parts of a cure modifier per hundred parts by weight of total epoxy resin, said cure modifier containing polar functionality, being soluble in said epoxy resin composition at said cure temperature and having sufficient solvating strength as to increase the solubility of said metal carboxylate salt in said epoxy resin to curing effective levels at said cure temperature.
A composition as in claim said cure modifier is present in an amount of from about 1 to about 20 parts per hundred parts by weight of total epoxy resin.
A composition as in claim 53 wherein said cyanate ester is selected from the poly-cyanate esters of bisphenol A, tetramethylbisphenol F, thiodiphenol, hexafluorobisphenol A, bisphenol E, dicyclopentadienephenol condensates or their partially trimerized blends.
A process for curing a heat-curable epoxy resin composition that is free of cure-effective amounts of an amine, carboxylic anhydride, or carboxylic acid in the acid form, comprising mixing together
- (a) at least one polyepoxide;
- (b) from about 0.1 to about 50 parts of a metal carboxylate salt curing agent per hundred parts by weight of total epoxy resin, said metal carboxylate salt being selected from a Group IA or Group IIA metal and being derived from a carboxylic acid containing from 1 to 4 carboxyl groups, wherein said metal carboxylate salt is substantially soluble in said epoxy resin composition at the cure temperature of said composition;
- and
- (c) from about 1 to about 100 parts of a cure modifier per hundred parts by weight of total epoxy resin, said cure modifier containing polar functionality, being soluble in said epoxy resin composition at said cure temperature and having sufficient solvating strength as to increase the solubility of said metal carboxylate salt in said epoxy resin to curing effective levels at said cure temperature;
- and heating said composition to a curing temperature of at least about 100.degree. C.
Dependencies are inferred from the claim text.