Rubber composition using a silane coupling agent having a specific distribution of sulfur

A rubber composition comprising:

• (i) a rubber component comprising at least one member selected from the group consisting of natural rubber and diene based synthetic rubbers;
• (ii) silica in an amount of 10 to 85 parts by weight per 100 parts by weight of the rubber component;
• (iii) a polysulfide silane coupling agent (B) in an amount of 1 to 20% by weight of the amount of the silica;
• wherein the polysulfide silane coupling agent (B) is obtained by a reaction of a polysulfide silane coupling agent (A) with at least one trivalent phosphorus compound selected from the group consisting of phosphine compounds represented by P(NR.sup.1 R.sup.2).sub.3 or P(R.sup.3).sub.3, phosphite compounds represented by P(OR.sup.4).sub.3, and compounds represented by the following formula (3):
• ##STR13## wherein R.sup.1 to R.sup.5 each independently represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group;
• the polysulfide silane coupling agent (A) is represented by the following general formula (1):
• (C.sub.n H.sub.2n+1 O).sub.3 Si--(CH.sub.2).sub.m --S.sub.p --(CH.sub.2).sub.m --Si(O C.sub.n H.sub.2n+1).sub.3 ( 1)
• (wherein n represents an integer of 1 to 3;
• m represents an integer of 1 to 9;
• and p represents an average number of sulfur atoms;
• and the average number of p is a positive number of 2 or more);
• the polysulfide silane coupling agent (B) is represented by the following general formula (2):
• (C.sub.n H.sub.2n+1 O).sub.3 Si--(CH.sub.2).sub.m --S.sub.p --(CH.sub.2).sub.m --Si(O C.sub.n H.sub.2n+1).sub.3 ( 2)
• (wherein n represents an integer of 1 to 3;
• m represents an integer of 1 to 9;
• and q represents an average number of sulfur atoms and is a positive number);
• the value of n in general formula (1) is the same as the value of n in general formula (2), and the value of m in general formula (1) is the same as the value of m in general formula (2);
• the value of p is less than the value of q;
• and
• the polysulfide silane coupling agent (A) and the polysulfide silane coupling agent (B) are each a mixture of polysulfide silanes.

A rubber composition comprising:

• (i) a rubber component comprising at least one member selected from the group consisting of natural rubber and diene based synthetic rubbers;
• (ii) silica in an amount of 10 to 85 parts by weight per 100 parts by weight of the rubber component;
• (iii) a polysulfide silane coupling agent (B) in an amount of 1 to 20% by weight of the amount of the silica;
• wherein the polysulfide silane coupling (B) agent is obtained by a reaction of a polysulfide silane coupling agent (A) with at least one trivalent phosphorus compound selected from the group consisting of phosphine compounds represented by P(NR.sup.1 R.sup.2).sub.3 or P(R.sup.3).sub.3, phosphite compounds represented by P(OR.sup.4).sub.3, and compounds represented by the following formula (3):
• ##STR14## wherein R.sup.1 to R.sup.5 each independently represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group;
• the polysulfide silane coupling agent (A) is represented by the following general formula (1):
• (C.sub.n H.sub.2n+1 O).sub.3 Si--(CH.sub.2).sub.m --S.sub.p --(CH.sub.2).sub.m --Si(O C.sub.n H.sub.2n+1).sub.3 ( 1)
• (wherein n represents an integer of 1 to 3;
• m represents an integer of 1 to 9;
• and p represents an average number of sulfur atoms and a positive number of 2 or more);
• and
• the polysulfide silane coupling agent (B) is represented by the following general formula (1):
• (C.sub.n H.sub.2n+1 O).sub.3 Si--(CH.sub.2).sub.m --S.sub.p --(CH.sub.2).sub.m --Si(O C.sub.n H.sub.2n+1).sub.3 ( 2)
• (wherein n represents an integer of 1 to 3;
• m represents an integer of 1 to 9;
• and q represents an average number of sulfur atoms and is a positive number);
• the value of q is less than the value of p;
• and
• the value of n in general formula (1) is the same as the value of n in general formula (2), and the value of m in general formula (1) is the same as the value of m in general formula (2).

A rubber composition comprising:

• (i) a rubber component comprising at least one member selected from the group consisting of natural rubber and diene based synthetic rubbers;
• (ii) silica in an amount of 10 to 85 parts by weight per 100 parts by weight of the rubber component;
• and
• (iii) a polysulfide silane coupling agent (B) in an amount of 1 to 20% by weight of the amount of the silica;
• wherein the polysulfide silane coupling agent (B) is obtained by a reaction of a polysulfide silane coupling agent (A) with at least one trivalent phosphorus compound selected from the group consisting of phosphine compounds represented by P(NR.sup.1 R.sup.2).sub.3 or P(R.sup.3).sub.3, phosphite compounds represented by P(OR.sup.4).sub.3, and compounds represented by the following formula (3):
• ##STR15## wherein R.sup.1 to R.sup.5 each independently represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, and
• the polysulfide silane coupling agent (A) is represented by the following general formula (1):
• (C.sub.n H.sub.2n+1 O).sub.3 Si--(CH.sub.2).sub.m --S.sub.p --(CH.sub.2).sub.m --Si(O C.sub.n H.sub.2n+1).sub.3 ( 1)
• (wherein n represents an integer of 1 to 3;
• m represents an integer of 1 to 9;
• and p represents an average number of sulfur atoms and integer of 2 or more).