Tough epoxy casting resins based on polybutadiene-polyoxyalkleneglycol copolymers

Claim 2

A curable composition comprising A) an epoxy resin having on average more than one epoxy group per molecule, B) a carboxylic anhydride curing agent for component A) selected from an anhydride of aliphatic, cycloaliphatic or aromatic dicarboxylic acids and C) about 5 to 40% by weight, relative to the amount of the components A), B) and C), of a liquid, segmented copolymer having hydroxyl, carboxyl, carboxylic anhydride or glycidyl end groups and containing at least one block derived from a polyalkylene glycol based on polypropylene glycol or polybutylene glycol and at least one block derived from an elastomeric copolymer based on butadiene, a polar, ethylenically unsaturated comonomer and, optionally, further ethylenically unsaturated comonomers, the said blocks being attached via identical or different functional groups --CO--X-- or --Y--CH 2 --CH(OH)--CH 2 --O-- in which X is --O--, --S-- or --NR 1 --, Y is --O--, --S--, --NR 1 -- or --CO--O-- and R 1 is hydrogen, alkyl, cycloalkyl, aryl or aralkyl.

Claim 3

A curable composition according to claim 1, wherein component A) is a cycloaliphatic epoxy resin or a polyglycidyl ether.

Claim 4

A curable composition according to claim 2, wherein component A) is a diglycidyl ether based on bisphenol.

Claim 5

A curable composition according to claim 3, wherein component A) is a liquid diglycidyl ether based on a bisphenol A.

Claim 6

A curable composition according to claim 1, wherein component B) is an anhydride of dicarboxylic acids or a mixture of these anhydrides which is liquid at temperatures below 40° C.

Claim 7

A curable composition according to claim 1, wherein component C) contains blocks derived from liquid butadiene acrylonitrile copolymers and difunctional polybutylene glycols or trifunctional or difunctional polypropylene glycols.

Claim 8

A cured product obtained by heating a curable composition according to claim 1.

Claim 9

A curable composition according to claim 6, wherein component C) is a segmented copolymer of the formula VI Z--[PAG--X.sub.1 BDC].sub.n --X.sub.1 --PAG--Z (VI) in which n is an integer from 1 to 10, PAG is the radical of a difunctional polypropylene glycol or polybutylene glycol after the functional groups have been removed, BDC is the radical of a difunctional, liquid butadiene/acrylonitrile copolymer after the functional groups have been removed, each X 1 is a bridge group of the formula --CO--X-- and/or --X--CO-- or --Y--CH 2 --CH(OH)--CH 2 --O-- and/or --O--CH 2 --CH(OH)--CH 2 --Y-- in which X is --O--, --S-- or NR 1 --, Y is --O--, --S--, NR 1 -- or --CO--O--, R 1 is hydrogen, alkyl, cycloalkyl, aryl or aralkyl, and Z is a radical selected from the group consisting of ##STR5## and --O--R 7 , in which R 4 is the radical of an aliphatic, cycloaliphatic or aromatic dicarboxylic acid after the two carboxyl groups have been removed, R 5 is the radical of an aromatic tricarboxylic acid after the three carboxyl groups have been removed, R 6 is the radical of an aromatic hydroxycarboxylic acid after the carboxyl group and the phenolic hydroxyl group have been removed and R 7 is hydrogen or a group of the formula ##STR6##