Unitary curable resin compositions
AssigneeAmicon Corporation
InventorJustin C. Bolger
Life of this patent
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Abstract
Novel thermoplastic curing agents formed by reacting an imidazole compound with an epoxy resin, and with--optionally as a third reactant--polyfunctional proton-donating compounds like polybasic acids or phenolic novolac resins. The curing agents are extraordinary in that they are useful in formulating novel storeable, one-package, heat-curable epoxy resin-based compositions. Moreover, they react synergistically with known curing agents, most notably dicyandiamid. The cured materials are of excellent quality. Processes, whereby the various novel materials of the invention are made, are also described.
Claims31
A curing agent suitable for use with epoxy resin systems comprising the solid thermoplastic reaction product of an epoxy resin containing a plurality of oxirane groups and an imidazole compound selected from ##STR13## wherein R is hydrogen, alkyl, alkenyl, aryl, or halo;
- ##STR14## wherein R is defined as above;
- ##STR15## wherein R is defined as above and R.sub.1 is alkyl, alkenyl, aryl, or halo;
- and
- d. mixtures of such compounds, the ratio of oxirane groups in the epoxy resin to the molecules of imidazole compound being between 1:1 and 2:1, said reaction product having a melting point from about 70.degree. C. to about 140.degree. C.
A curing agent suitable for use with epoxy resin systems comprising a solid thermoplastic reaction product of (1) an epoxy resin containing a plurality of oxirane groups and (2) an imidazole compound selected from ##STR16## wherein R is hydrogen, alkyl, alkenyl, aryl or halo;
- ##STR17## wherein R is defined as above;
- ##STR18## wherein R is defined as above and R.sub.1 is alkyl, alkenyl, aryl or halo;
- d. mixtures of such compounds,
- and (3) a polyfunctional proton-donor compound selected from the group consisting of polycarboxylic acids and phenolic novolac resins, the ratio of oxirane groups in the epoxy resin to the molecules of imidazole compound being between 0.8:1 and 2.2:1 and the ratio of acid equivalents of proton-donor compound to molecules of imidazole compound being up to 1.5:1, said epoxy resin having an epoxide equivalent weight from about 170 to about 2000, said reaction product having a melting point from about 70.degree. C. to about 140.degree. C.
A process for converting a polyepoxide having more than one vicinal epoxy group per molecule into an insoluble, infusible product which comprises heating said polyepoxide at an elevated temperature with a curing amount of a combination comprising (1) a fusible, ketone-soluble adduct prepared by reacting (a) an epoxy compound containing at least two vicinal epoxy groups with (b) an imidazole compound of the general formula:
- ##STR25## wherein each R is hydrogen or a hydrocarbon radical selected from the group consisting of alkyl and cycloalkyl radicals of up to 12 carbon atoms and aryl radicals, at a temperature from about 50.degree. to 250.degree. C. and for a time sufficient to complete the reaction, said epoxy compound and imidazole compound being employed in amounts to furnish from 0.8 to 2.2 epoxy groups per secondary amino group and (2) an epoxy co-curing agent selected from the group consisting of at least one carboxylic acid anhydride and dicyandiamide.
A shelf-stable, heat-curable composition comprising (A) a polyepoxide having more than one vicinal epoxy group per molecule and a curing amount of (B) a combination comprising (1) a fusible, ketone-soluble adduct prepared by reacting (a) an epoxy compound containing at least two vicinal epoxy groups with (b) an imidazole compound of the general formula:
- ##STR26## wherein each R is hydrogen or a hydrocarbon radical selected from the group consisting of alkyl and cycloalkyl radicals of up to 12 carbon atoms and aryl radicals, at a temperature from about 50.degree. to 250.degree. C and for a time sufficient to complete the reaction, said epoxy compound and imidazole compound being employed in amounts to furnish from 0.8 to 2.2 epoxy groups per secondary amino groups, and (2) an epoxy co-curing agent selected from the group consisting of at least one carboxylic acid anhydride and dicyandiamide.
Dependencies are inferred from the claim text.