Modified disulfide polymer composition and method for making same from mercaptan terminated disulfide polymer and diethyl formal mercaptan terminated polysulfide

A liquid polymer composition curable to a solid elastomer having excellent thermal stability, good adhesion after exposure to fuel and high strength, said composition consisting essentially of a polymeric mixture of

• (a) from 90 mole percent to 25 mole percent of thioether mercaptan terminated disulfide polymer of the formula HS(RSS).sub.m R'SH and
• (b) from 10 mole percent to 75 mole percent of diethyl formal mercaptan terminated polysulfide polymer of the formula HS(RSS).sub.n RSH;
• wherein in the formulae R is --C.sub.2 H.sub.4 --O--CH.sub.2 --O--C.sub.2 H.sub.4 --;
• R' is a divalent alkyl thioether of from 4 to 20 carbon atoms and the value of m and n is such that the diethyl formal mercaptan terminated polysulfide and the thioether mercaptan terminated disulfide polymer have an average molecular weight of between about 1,000 and about 4,000.

A liquid mercaptan terminated disulfide polymer curable to a solid elastomer having excellent thermal stability, said mercaptan terminated disulfide polymer having the formula HS(RSS).sub.m R'SH wherein R is --C.sub.2 H.sub.4 --O--CH.sub.2 --O--C.sub.2 H.sub.4 --;

• R' is a divalent member selected from the group consisting of alkyl of from 2 to 12 carbon atoms;
• alkyl thioether of from 4 to 20 carbon atoms;
• alkyl ether of from 4 to 20 carbon atoms and one oxygen atom;
• alkyl ether of from 4 to 20 carbon atoms and from 2 to 4 oxygen atoms each of which is separated from the other by at least 2 carbon atoms, alicyclic of from 6 to 12 carbon atoms and aromatic lower alkyl;
• and the value of m is such that mercaptan terminated disulfide polymer has a molecular weight of between 1,000 to about 4,000.

A method for producing a liquid polymer composition curable to a solid elastomer having excellent thermal stability which consists essentially of a polymeric mixture of

• (a) from 90 mole percent to 25 mole percent of mercaptan terminated disulfide polymer of the formula HS(RSS).sub.m R'SH and
• (b) from 10 mole percent to 75 mole percent of diethyl formal mercaptan terminated polysulfide polymer of the formula HS(RSS).sub.n RSH;
• wherein in the formulae R is --C.sub.2 H.sub.4 --O--CH.sub.2 --O--C.sub.2 H.sub.4 --;
• R' is a divalent member selected from the group consisting of alkyl of from 2 to 12 carbon atoms;
• alkyl thioether of from 4 to 20 carbon atoms;
• alkyl ether of from 4 to 20 carbon atoms and one oxygen atom;
• alkyl ether of from 4 to 20 carbon atoms and from 2 to 4 oxygen atoms each of which is separated from the other by at least 2 carbon atoms, alicyclic of from 6 to 12 carbon atoms and aromatic lower alkyl;
• and the value m and n is such that the diethyl formal mercaptan terminated disulfide polymer and the mercaptan terminated polysulfide polymer have an average molecular weight of between about 1,000 and about 4,000, which comprises
• forming a reaction admixture consisting essentially of (1) reactant one having the formula HS(RSS).sub.m RSH wherein R has the same significance as set forth above and the value of m is such that said reactant has a molecular weight of between about 2,000 and about 8,000;
• (2) a reactant two having the formula R'(SH).sub.2 wherein R' has the same significance as set forth above, the molar ratio of reactant two to reactant one being 0.3:1 to 7:1, and (3) a catalytic effective amount of an organic amine catalyst having a pKb value of at least about 10;
• the temperature of said reaction mixture being at least ambient.

A method for producing a liquid polymer composition curable to a solid elastomer having excellent thermal stability which consists essentially of a polymer mixture of

• (a) from 90 mole percent to 25 mole percent of mercaptan terminated disulfide polymer of the formula HS(RSS).sub.m R'SH and
• (b) from 10 mole percent to 75 mole percent of diethyl formal mercaptan terminated polysulfide polymer of the formula HS(RSS).sub.n RSH;
• wherein in the formulae R is --C.sub.2 H.sub.4 --O--CH.sub.2 --O--C.sub.2 H.sub.4 --;
• R' is a divalent alkyl thioether of from 4 to 20 carbon atoms and the value of m and n is such that the diethyl formal mercaptan terminated disulfide polymer and the mercaptan terminated polysulfide polymer have an average molecular weight of between about 1,000 and about 4,000, which comprises
• forming a reaction admixture consisting essentially of (1) reactant one having the formula HS(RSS).sub.m RSH wherein R has the same significance as set forth above and the value of m is such that said reactant has a molecular weight of between about 2,000 and about 8,000;
• (2) reactant two having the formula R'(SH).sub.2 wherein R' has the same signficance as set forth above, the molar ratio of reactant two to reactant one being 0.3:1 to 7:1, and (3) a catalytic effective amount of an organic amine catalyst having a pKb value of at least about 10;
• the temperature of said reaction mixture being at least ambient.