Diamino disulfide curatives for polyurethanes

A curative comprising a blend consisting of (a) an organic diamino disulfide selected from the group consisting of:

• 1. diamino diphenyl disulfides with amino groups located in different phenyl radicals and having the amino groups located in positions ortho to the disulfide group,
• 2. diamino dinaphthyl disulfides having melting points below 150.degree. C., and with amino groups located in different naphthyl radicals,
• 3. organic diamino disulfides having the structure NH.sub.2 --Ar--S--S--R'--NH.sub.2 or NH.sub.2 --R'--S--S--R'--NH.sub.2 in which Ar is an aryl radical and R' is a tertiary aliphatic or cycloaliphatic radical in which the amino group is attached to the tertiary carbon atom, and
• 4. organic diamino aryl disulfides in which one of the radicals attached to the disulfide group is a diaminoaryl radical and the other radical attached to the disulfide group is either an aryl or a lower alkyl radical, and (b) an aromatic diamine.

A curative comprising a blend consisting of (a) an organic diamino disulfide selected from the group consisting of:

• 1. diamino diphenyl disulfides with amino groups located in different phenyl radicals and having the amino groups located in positions ortho to the disulfide group,
• 2. diamino dinaphthyl disulfides having melting points below 150.degree. C., and with amino groups located in different naphthyl radicals,
• 3. organic diamino disulfides having the structure NH.sub.2 --Ar--S--S--R'--NH.sub.2 or NH.sub.2 --R'--S--S--R'--NH.sub.2 in which Ar is an aryl radical and R' is a tertiary aliphatic or cycloaliphatic radical in which the amino group is attached to the tertiary carbon atom,
• 4. organic diamino aryl disulfides in which one of the radicals attached to the disulfide group is a diaminoaryl radical and the other radical attached to the disulfide group is either an aryl or a lower alkyl radical, and
• 5. substituted para, para' diamino diphenyl disulfides having substituents selected from the group consisting of lower alkyl and lower alkoxy radicals, and (b) a diol.

A curative comprising a blend consisting of (a) an organic diamino disulfide selected from the group consisting of:

• 1. diamino diphenyl disulfides with amino groups located in different phenyl radicals and having the amino groups located in positions ortho to the disulfide group,
• 2. diamino dinaphthyl disulfides having melting points below 150.degree. C., and with amino groups located in different naphthyl radicals,
• 3. organic diamino disulfides having the structure NH.sub.2 --Ar--S--S--R'--NH.sub.2 or NH.sub.2 --R'--S--S--R'--NH.sub.2 in which Ar is an aryl radical and R' is a tertiary aliphatic or cycloaliphatic radical in which the amino group is attached to the tertiary carbon atom,
• 4. organic diamino aryl disulfides in which one of the radicals attached to the disulfide group is a diaminoaryl radical and the other radical attached to the disulfide group is either an aryl or a lower alkyl radical, and
• 5. substituted para, para'-diamino diphenyl disulfides having substituents selected from the group consisting of lower alkyl and lower alkoxy radicals, (b) an aromatic diamine, and (c) a diol.

The process of producing a polyurethane composition which comprises intimately admixing a polyurethane prepolymer having isocyanato terminal groups with an organic diamino disulfide curative selected from the group consisting of:

• a. diamino diphenyl disulfides with amino groups located in different phenyl radicals and having the amino groups located in positions ortho to the disulfide group,
• b. diamino dinaphthyl disulfides having melting points below 150.degree. C., and with amino groups located in different naphthyl radicals,
• c. organic diamino disulfides having the structure NH.sub.2 --Ar--S--S--R'--NH.sub.2 or NH.sub.2 --R'--S--S--R'--NH.sub.2 in which Ar is an aryl radical and R' is a tertiary aliphatic or cycloaliphatic radical in which the amino group is attached to the tertiary carbon atom,
• d. organic diamino aryl disulfides in which one of the radicals attached to the disulfide group is a diaminoaryl radical and the other radical attached to the disulfide group is either an aryl or a lower alkyl radical, and
• e. 3,5,3',5'-tetra-lower-alkyl-4,4'-diaminodiphenyl disulfides, in an amount such that the stoichiometric ratio of amino groups to isocyanato groups ranges from 0.50 to 0.90 and allowing the reaction mixture to cure by maintaining a temperature ranging from room temperature to 95.degree. C.

The process of producing a polyurethane composition which comprises reacting (A) a polymeric polyol, (B) an organic polyisocyanate and (C) an organic diamino disulfide selected from the group consisting of

• a. diamino diphenyl disulfides with amino groups located in different phenyl radicals and having the amino groups located in positions ortho to the disulfide group,
• b. diamino dinaphthyl disulfides having melting points below 150.degree. C., and with amino groups located in different naphthyl radicals,
• c. organic diamino disulfides having the structure NH.sub.2 --Ar--S--S--R'--NH.sub.2 or NH.sub.2 --R'--S--S--R'--NH.sub.2 in which Ar is an aryl radical and R' is a tertiary aliphatic or cycloaliphatic radical in which the amino group is attached to the tertiary carbon atom,
• d. organic diamino aryl disulfides in which one of the radicals attached to the disulfide group is a diaminoaryl radical and the other radical attached to the disulfide group is either an aryl or a lower alkyl radical, and
• e. 3,5,3',5'-tetra-lower-alkyl-4,4'-diaminodiphenyl disulfides, with the amounts of (A), (B), and (C) being such that the stoichiometric ratio of amino groups to isocyanato groups ranges from 0.50 to 0.90 and allowing the reaction mixture to cure in the presence of a catalyst for the reaction of isocyanato groups with hydroxyl groups.