Activated isocyanate prepolymers and a process for the production of elastomeric polyurethane resins

Claim 2

In a process for the production of polyurethane elastomers by the reaction of 1,5-naphthylene diisocyanate with a substantially linear, relatively high molecular weight polyhydroxyl compound to produce a prepolymer containing isocyanate groups, followed by a reaction with a chain lengthening agent in the presence of an activator, the improvement wherein the activator used is a compound corresponding to the general formula: ##STR6## wherein R 1 represents an alkyl, cycloalkyl, aralkyl or aryl group with 1 to 15 carbon atoms which may be substituted by a urea group corresponding to the general formula: ##STR7## wherein R 2 , R 3 and R 4 represent hydrogen, phenyl groups or straight or branched chain alkyl groups having 1 to 6 carbon atoms, and wherein the operating conditions employed are such that substantially homogeneous elastomers are obtained.

Claim 3

A process according to claim 1, wherein the relatively high molecular weight polyhydroxyl compound used is a polyester diol having a molecular weight of from 1,000 to 3,000.

Claim 4

A process according to claim 1, characterized in that the chain lengthening agent used is 1,4-butanediol, 2,3-butanediol or thiodiglycol.

Claim 5

A process according to claim 1, wherein the activator is used in a quantity of from 0.01 to 0.5% by weight, based on the sum of the naphthylene diisocyanate and the relatively high molecular weight polyhydroxyl compound.

Claim 6

A process according to claim 1, wherein the activator used is N-methylurea or N,N'-dimethylurea.

Claim 7

Activated prepolymers with isocyanate end groups which are stable in storage consisting of (a) compounds corresponding to the general formula: ##STR8## wherein a represents a group corresponding to the formula: ##STR9## D represents a divalent group such as is obtained by removal of the hydroxyl groups from a glycol having a molecular weight of from 500 to 6,000 and n represents an integer of from 1 to 5, (b) from 0.001 to 1% by weight, based on (a)+(b), of a compound corresponding to the general formula: ##STR10## wherein R 1 represents an alkyl, cycloalkyl, aralkyl or aryl group with 1 to 15 carbon atoms which may be substituted by a urea group corresponding to the general formula ##STR11## wherein R 2 , R 3 and R 4 represent hydrogen, phenyl groups or straight or branched chain alkyl groups having 1 to 6 carbon atoms; and (c) a monomeric 1,5-naphthylene diisocyanate.

Claim 8

Activated prepolymers with isocyanate end groups which are stable in storage consisting of (a) compounds corresponding to the general formula: ##STR8## wherein a represents a group corresponding to the formula: ##STR9## D represents a divalent group such as is obtained by removal of the hydroxyl groups from a glycol having a molecular weight of from 500 to 6,000 and n represents an integer of from 1 to 5, (b) from 0.001 to 1% by weight, based on (a)+(b), of a compound corresponding to the general formula: ##STR10## wherein R 1 represents an alkyl, cycloalkyl, aralkyl or aryl group with 1 to 15 carbon atoms which may be substituted by a urea group corresponding to the general formula ##STR11## wherein R 2 , R 3 and R 4 represent hydrogen, phenyl groups or straight or branched chain alkyl groups having 1 to 6 carbon atoms; and (c) a monomeric 1,5-naphthylene diisocyanate.

Claim 9

Prepolymers according to claim 6, wherein D denotes a divalent group as obtained by the removal of the hydroxyl group from a polyester diol having a molecular weight of from 1,000 to 3,000.

Claim 10

Prepolymers according to claim 6, wherein n represents the number 1 or 2.