Method for producing modified conjugated diene polymer, polymer composition, crosslinked polymer and tire
A modified conjugated diene polymer obtained by modifying a conjugated diene polymer that is obtained by polymerizing a conjugated diene compound or polymerizing a conjugated diene compound and an aromatic vinyl compound is produced by a production method comprising a first modification step wherein an unsaturated binding site at least either in the skeleton or at the side chain of the conjugated diene polymer is reacted with a first compound having a group 4 or 13 element of the periodic table.
1. A method for modifying a conjugated diene polymer obtained by polymerizing a conjugated diene compound or polymerizing a conjugated diene compound and an aromatic vinyl compound, the method comprising:
reacting an active end of the conjugated diene polymer with a third compound having a functional group that interacts with silica;
subsequently reacting an unsaturated binding site in at least one of a skeleton and a side chain of the conjugated diene polymer with a first compound having a boron-hydrogen bond; and
subsequently reacting the conjugated diene polymer with a second compound having a functional group that interacts with silica, the functional group comprising at least one nitrogen atom;
wherein the conjugated diene polymer is a polymer obtained by polymerization in the presence of an alkali metal compound or an alkaline earth metal compound.
2. The method for producing a modified conjugated diene polymer according to claim 1 , wherein the third compound is at least one selected from the group consisting of:
(I) a compound (a-1) represented by the following formula (1):
wherein:
A 1 is a monovalent functional group which has at least one atom selected from the group consisting of a nitrogen atom, a phosphorus atom, and a sulfur atom, does not have an active hydrogen, and binds to R 3 with the nitrogen atom, the phosphorus atom, or the sulfur atom;
R 1 and R 2 are each a hydrocarbyl group;
R 3 is a hydrocarbylene group; and
n is an integer of 0 to 2;
provided that, when plural R 1 and R 2 groups are present, the groups R 1 and R 2 may each be the same or different;
(II) a compound (a-2) having, in the molecule, at least one functional group (x1) selected from the group consisting of a cyclic ether group and a (thio)carbonyl group and a group (x2) different from the functional group (x1), which has at least one atom selected from the group consisting of a nitrogen atom, a phosphorus atom, an oxygen atom, and a sulfur atom and does not have an active hydrogen; and
(III) a compound (a-3) having two or more iso(thio)cyanate groups in the molecule.
3. A method for preparing a polymer composition comprising:
modifying a conjugated diene polymer by the method according to claim 1 ; and
blending the modified conjugated diene polymer with silica and a crosslinking agent.
4. A method for producing a crosslinked polymer, comprising:
preparing a polymer composition by the method of claim 3 ; and
cross-linking the polymer composition.
5. A method for producing a tire, comprising:
producing a crosslinked polymer by the method of claim 4 ;
wherein producing the crosslinked polymer comprises molding the polymer composition and crosslinking to form a tread or a side wall of the tire.