Blocked mercaptosilane coupling agents for filled rubbers

A rubber composition comprising:

• a) a blocked mercaptosilane selected from the group consisting of:
• [[(ROC(═O))p—(G)j]k—Y—S]r—G—(SiX3)s (1);
• and
• [(X3Si)q—G]a—[Y—[S—G—SiX3]b]c (2)
• wherein
• Y is a polyvalent species (Q)zA(═E), each wherein the atom A attached to the unsaturated heteroatom E is attached to the sulfur, which in turn is linked via a group G to the silicon atom;
• each R is chosen independently from hydrogen, straight, cyclic or branched alkyl that may or may not contain unsaturation, alkenyl groups, aryl groups, and aralkyl groups, with each R containing from 1 to 18 carbon atoms;
• each G is independently a monovalent or polyvalent group derived by substitution of alkyl, alkenyl, aryl or aralkyl wherein G can contain from 1 to 18 carbon atoms, with the proviso that if Y is —C(═O)—, G is not such that the blocked mercaptosilane would contain an α,β-unsaturated carbonyl, and if G is univalent, G can be a hydrogen atom;
• X is independently selected from the group consisting of —Cl, —Br, RO—, RC(═O)O—, R2C═NO—, R2NO—, R2N—, —R, and —(OSiR2)t(OSiR3) wherein each R is as above and at least one X is not —R;
• Q is oxygen, sulfur, or (—NR—);
• A is carbon, sulfur, phosphorus, or sulfonyl;
• E is oxygen, sulfur, or NR;
• p is 0 to 5;
• r is 1 to 3;
• z is 0 to 2;
• q is 0 to 6;
• a is 0 to 7;
• b is 1 to 3;
• j is 0 to 1, but it may be 0 only if p is 1;
• c is 1 to 6, t is 0 to 5;
• s is 1 to 3;
• k is 1 to 2, with the provisos that (A) if A is carbon, sulfur, or sulfonyl, then (i) a+b is 2 and (ii) k is 1;
• (B) if A is phosphorus, then a+b is 3 unless both (i) c is greater than 1 and (ii) b is 1, in which case a is c+1;
• and (C) if A is phosphorus, then k is 2;
• b) an organic polymer;
• c) a filler;
• and
• d) a deblocking agent.