Abstract: The invention provides a modified liquid diene polymer that allows a rubber composition to give a crosslinked product which contains a filler in a dispersed state ideal for attaining enhanced properties and which also exhibits excellent properties such as wet grip and abrasion resistance. The invention also provides a rubber composition including the modified liquid diene polymer, a crosslinked product thereof, and a tire which includes a portion including the composition or the crosslinked product. The modified liquid diene polymer is a product of modification, with a specific silane compound, of a liquid diene block copolymer including a polymer block (b?1) or (b?1) containing butadiene units and a polymer block (b?2) or (b?2). The modified liquid diene polymer has a functional group derived from the silane compound, and satisfies specific conditions.

Abstract: A method for producing a hydrogenated polymer composition including a hydrogenated conjugated diene modified polymer that has a boron-containing functional group, the method including: (1) anionically polymerizing a monomer including a conjugated diene in the presence of a reactive metal or reactive metal compound capable of causing anionic polymerization to produce a reactive terminal polymer (Z); (2) reacting the reactive terminal polymer (Z) obtained in (1) with a boric acid compound that has at least two partial structures represented by B—O—R (I), and in which at least one R bonded to an oxygen atom in the partial structure (I) has a Taft's steric parameter Es value of ?0.30 or less to obtain an unhydrogenated conjugated diene modified polymer having a boron-containing functional group; and (3) hydrogenating at least some of carbon-carbon double bonds contained in conjugated diene units included in the unhydrogenated conjugated diene modified polymer obtained in (2).

Abstract: A method for producing a polymer composition including modified polymers having a boron-containing functional group includes anionically polymerizing at least one monomer selected from the group consisting of conjugated dienes and aromatic vinyl compounds in the presence of an active metal or an active metal compound capable of catalyzing anionic polymerization to produce a terminal-active polymer (Z), and reacting the terminal-active polymer (Z) obtained with a boric acid compound having at least two or more partial structures represented by the formula B-O-R (B is boron, O is oxygen, and R is an organic group) and having a Taft’s steric parameter Es of -0.30 or less with respect to at least one of Rs bonded to the oxygen atom in the partial structures.

Abstract: Disclosed herein is a rubber composition containing 100 parts by mass of a solid rubber (A), 0.1 to 50 parts by mass of a modified liquid diene rubber (B) having a functional group derived from a silane compound represented by the formula (1), and 20 to 200 parts by mass of a filler (C), the modified liquid diene rubber (B) satisfying (i) to (iii): (i) a weight average molecular weight (Mw) is not less than 1,000 and less than 15,000; (ii) a vinyl content is not more than 70 mol %; and (iii) an average number of functional groups per molecule of the modified liquid diene rubber (B) is 1 to 20.

Abstract: A rubber composition includes 100 parts by mass of a solid rubber (A), 0.1 to 50 parts by mass of a modified liquid diene rubber (B) having a functional group derived from a silane compound represented by the formula (1), and 20 to 200 parts by mass of a filler (C), the modified liquid diene rubber (B) satisfying (i) to (iii) below: (i) The weight average molecular weight (Mw) is 15,000 to 120,000. (ii) The vinyl content is not more than 70 mol %. (iii) The average number of functional groups per molecule of the modified liquid diene rubber (B) is 1 to 30.

Abstract: The invention provides a modified liquid diene polymer that allows a rubber composition to give a crosslinked product which contains a filler in a dispersed state ideal for attaining enhanced properties and which also exhibits excellent properties such as wet grip and abrasion resistance. The invention also provides a rubber composition including the modified liquid diene polymer, a crosslinked product thereof, and a tire which includes a portion including the composition or the crosslinked product. The modified liquid diene polymer is a product of modification, with a specific silane compound, of a liquid diene block copolymer including a polymer block (b?1) or (b?1) containing butadiene units and a polymer block (b?2) or (b?2). The modified liquid diene polymer has a functional group derived from the silane compound, and satisfies specific conditions.

Abstract: A rubber composition includes 100 parts by mass of a solid rubber (A), 0.1 to 50 parts by mass of a modified liquid diene rubber (B) having a functional group derived from a silane compound represented by the formula (1), and 20 to 200 parts by mass of a filler (C), the modified liquid diene rubber (B) satisfying (i) to (iii) below: (i) The weight average molecular weight (Mw) is 15,000 to 120,000. (ii) The vinyl content is not more than 70 mol %. (iii) The average number of functional groups per molecule of the modified liquid diene rubber (B) is 1 to 30.

Abstract: Disclosed herein is a rubber composition containing 100 parts by mass of a solid rubber (A), 0.1 to 50 parts by mass of a modified liquid diene rubber (B) having a functional group derived from a silane compound represented by the formula (1), and 20 to 200 parts by mass of a filler (C), the modified liquid diene rubber (B) satisfying (i) to (iii): (i) a weight average molecular weight (Mw) is not less than 1,000 and less than 15,000; (ii) a vinyl content is not more than 70 mol %; and (iii) an average number of functional groups per molecule of the modified liquid diene rubber (B) is 1 to 20.