US 5,629,379 AGranted

Anhydride-hardened epoxy resin with polybutadiene-maleic anhydride adduct

OwnerJohn D. Harperinventor

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Abstract

Toughened epoxy resin systems having high temperature capabilities of from 250.degree. to 350.degree. C. prepared by carefully curing blends of epoxy resins having an average epoxy functionality greater than two with bicycloalkene dicarboxylic anhydride hardener, maleinized polybutadiene toughening agent, supplemental hardener selected from the group consisting of aromatic tetracarboxylic dianhydrides and bismaelimides of aromatic diamines, and epoxy/anhydride accelerator.

Claims8

Dependent claims

A toughened epoxy resin system having a glass transition temperature of from about 250.degree. C. to 350.degree. C., said resin system being prepared from a blend comprising the following ingredients:

(1) An epoxy resin component selected from the group consisting of
(a) a single epoxy resin having an epoxy functionality greater than two epoxy groups per molecule;
and
(b) a mixture of epoxy resins so chosen that all epoxy resins in said mixture have epoxy functionality of at least two epoxy groups per molecule, and that the average epoxy functionality of said mixture is greater than two epoxy groups per molecule;
(2) An anhydride hardener component consisting essentially of
(a) a bicyclo alkene dicarboxylic acid anhydride;
and
(b) a 1,2-polybutadiene-maleic anhydride adduct containing from about 15 to 25% combined maleic anhydride and having an equivalent weight in the range of from about 400 to 700;
the stoichiometric ratio of anhydride hardener (2)(a) to (2)(b) being from 75 to 1 equivalents to 2 to 1 equivalents;
and the stoichiometric ratio of said anhydrides (2)(a) and (2)(b) combined to said epoxy resin component (1) being from about 0.7 to 1 equivalent to 1 to 1 equivalent;
(3) A supplemental hardener component selected from the group consisting of
(a) an aromatic tetracarboxylic acid dianhydride in an amount of from 1% to 100% by weight of said bicyclo alkene dicarboxylic acid anhydride component (2)(a);
and
(b) an aromatic diamine bis(maleimide) in an amount of from 1% to 25% of the total mixture;
(4) An epoxy/anhydride accelerator selected from the group consisting of dialkyl imidazole-2-thiones, dialkylimidazoles, tertiary amines, dicyandiamide, Lewis bases, and mixtures thereof, and alternately Lewis acids,
said blend being subjected to preliminary curing at from about 80.degree. C. to 120.degree. C. till said blend has gelled, and then to further curing at temperatures of from 200.degree. C. to 300.degree. C. till curing is complete, thereby obtaining final toughened solid epoxy resin.

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Dependencies are inferred from the claim text.

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Abstract

(1) An epoxy resin component selected from the group consisting of
(a) a single epoxy resin having an epoxy functionality greater than two epoxy groups per molecule;
and
(b) a mixture of epoxy resins so chosen that all epoxy resins in said mixture have epoxy functionality of at least two epoxy groups per molecule, and that the average epoxy functionality of said mixture is greater than two epoxy groups per molecule;
(2) An anhydride hardener component consisting essentially of
(a) a bicyclo alkene dicarboxylic acid anhydride;
and
(b) a 1,2-polybutadiene-maleic anhydride adduct containing from about 15 to 25% combined maleic anhydride and having an equivalent weight in the range of from about 400 to 700;
the stoichiometric ratio of anhydride hardener (2)(a) to (2)(b) being from 75 to 1 equivalents to 2 to 1 equivalents;
and the stoichiometric ratio of said anhydrides (2)(a) and (2)(b) combined to said epoxy resin component (1) being from about 0.7 to 1 equivalent to 1 to 1 equivalent;
(3) A supplemental hardener component selected from the group consisting of
(a) an aromatic tetracarboxylic acid dianhydride in an amount of from 1% to 100% by weight of said bicyclo alkene dicarboxylic acid anhydride component (2)(a);
and
(b) an aromatic diamine bis(maleimide) in an amount of from 1% to 25% of the total mixture;
(4) An epoxy/anhydride accelerator selected from the group consisting of dialkyl imidazole-2-thiones, dialkylimidazoles, tertiary amines, dicyandiamide, Lewis bases, and mixtures thereof, and alternately Lewis acids,
said blend being subjected to preliminary curing at from about 80.degree. C. to 120.degree. C. till said blend has gelled, and then to further curing at temperatures of from 200.degree. C. to 300.degree. C. till curing is complete, thereby obtaining final toughened solid epoxy resin.

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