Polyether urea epoxy curing agent

A curable epoxy resin composition consisting essentially of:

• a vicinal polyepoxide;
• and, an effective amount of
• a polyether urea curing agent of the formula:
• ##STR13## wherein A is a polyoxyalkylene radical containing from about 1 to 15 oxyalkylene groups wherein each oxyalkylene group contains from 2 to about 4 carbon atoms;
• R is a hydrocarbon radical containing from 2 to 5 carbon atoms and forming from 2 to 4 oxycarbon linkages with and B;
• B is a polyoxyalkylene amino radical containing from about 1 to 15 oxyalkylene groups wherein each oxyalkylene group contains from 2 to about 4 carbon atoms;
• X is a C=O radical;
• c and d are from 1 to 3 and chosen so that their sum is from 2 to 4;
• e is a number from 1 to 3;
• f is a number from 1 to 3;
• g is a number from 1 to 3;
• y is a number from 0 to about 5;
• z is a number from 0 to 2.

An epoxy resin curing agent for curing vicinal epoxy resins consisting essentially of:

• a polyether urea having terminal primary amino groups and being formed by the reaction of a compound selected from a group consisting of urea and urea forming compounds with a polyoxyalkylenepolyamine of the formula:
• ##STR16## wherein X is a hydrogen, a methyl radical, or an ethyl radical;
• Z is a hydrocarbon radical having 2 to 5 carbon atoms forming from 2 to 4 external ether linkages;
• n is a number from 1 to about 15;
• and r is a number from 2 to 4 wherein the molar ratio of said compound to said polyoxyalkylenepolyamine is about 0.50 to 0.83.

An epoxy resin curing agent consisting essentially of:

• ##STR17## wherein A is a polyoxyalkylene radical containing from about 1 to about 15 oxyalkylene groups wherein each oxyalkylene group contains from 2 to about 4 carbon atoms;
• R is a hydrocarbon radical containing from 2 to 5 carbon atoms forming from 2 to 4 oxycarbon linkages with A and B;
• B is a polyoxyalkylene amino radical containing from about 1 to 15 oxyalkylene groups wherein each oxyalkylene group contains from 2 to about 4 carbon atoms;
• X is a C=O radical;
• c and d are from 1 to 3 and chosen so that their sum is from 2 to 4;
• e is a number from 1 to 3;
• f is a number from 1 to 3;
• g is a number from 1 to 3;
• y is a number from 0 to 5;
• z is a number from 0 to 2.

A process for preparing a polyether urea having terminal primary amino groups comprising the steps of:

• reacting, at temperatures of 100.degree. C to 200.degree. C a compound selected from a group consisting of urea and urea forming compounds with a polyoxyalkylenepolyamine of the formula:
• ##STR20## wherein X is a hydrogen, a methyl radical, or an ethyl radical, Z is a hydrocarbon radical having 2 to 5 carbon atoms forming from 2 to 4 ether linkages, n is a number from 1 to about 15;
• r is a number from 2 to 4 wherein the molar ratio of said compound to said polyoxyalkylenepolyamine is about 0.50 to 0.83;
• and,
• recovering said polyether urea from the reaction mixture.

A curable epoxy resin consisting essentially of:

• a diglycidyl ether of 4,4'-isopropylidenebisphenol;
• and,
• an effective amount of a curing agent wherein said curing agent consists essentially of a polyether urea formed by reacting a polyoxypropylenepolyamine, having a molecular weight of about 400 with an effective amount of urea;
• and, a polyoxypropylenepolyamine having a molecular weight of from about 200-2,000 in a ratio of said polyether urea to said polyoxypropylenepolyamine of from about 5:1 to 1:5 by weight.