Method for producing modified conjugated diene based (co)polymer, modified conjugated diene based (co)polymer, and rubber composition

1. A method for producing a modified conjugated diene based (co)polymer, the method comprising reacting a conjugated diene based (co)polymer with a metal halide compound to obtain a modified conjugated diene based (co)polymer,

wherein the conjugated diene based (co)polymer has a weight-average molecular weight of 150,000 to 2,000,000, and is obtained by a process comprising bonding, to a polymer having at least a conjugated diene unit, an alkoxysilyl group and an [optionally] protected primary amino group, where the polymer is obtained by polymerization with an initiator comprising an organic lithium,

the conjugated diene based (co)polymer is reacted with the metal halide compound of such an amount that the total mols of the halogen atom becomes 1 to 10 times the total mols of the [optionally] protected primary amino group possessed by the conjugated diene based (co)polymer, to obtain the modified conjugated diene based (co)polymer, and

a ratio of the total mols of chlorine atoms of the metal halogen compound is 2.1 times or more of the total mols of the organic group contained in the organic lithium.

2. The method according to claim 1 , wherein the polymer having at least a conjugated diene unit is a homopolymer of a conjugated diene, or a copolymer of a conjugated diene and an aromatic vinyl compound.

3. The method according to claim 1 , wherein the metal halide compound is a compound which generates hydrogen halide upon hydrolysis.

4. The method according to claim 1 , wherein the metal halide compound is a compound which comprises at least one kind of metal atom selected from the group consisting of silicon (Si), tin (Sn), aluminum (Al), zinc (Zn), titanium (Ti) and zirconium (Zr).

5. The method according to claim 1 , wherein the metal halide compound is at least one kind of compound selected from the group consisting of trimethylsilyl chloride, dimethyldichlorosilane, methyltrichlorosilane, silicon tetrachloride, methyldichlorosilane, tin tetrachloride, diethyl aluminum chloride, ethyl aluminum sesquichloride, ethyl aluminum dichloride, zinc chloride, titanium tetrachloride, titanocene dichloride, zirconium tetrachloride and zirconocene dichloride.

6. The method according to claim 1 , wherein the conjugated diene based (co)polymer is a polymer obtained by a process comprising:

adding an initiator comprising at least either of an organic alkali metal and an organic alkaline earth metal to a hydrocarbon solvent comprising a conjugated diene or a conjugated diene and an aromatic vinyl compound to obtain a mixture;

subjecting the mixture to anionic polymerization to obtain a polymer; and

reacting the polymerization active terminal of the polymer obtained with at least one kind of compound selected from a compound of formula (1) and a compound of formula (2)

wherein in formula (1), R 1 is an alkylene group having 1 to 12 carbon atoms; R 2 and R 3 are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group; R 4 , R 5 and R 6 are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group, or two of them may bond to each other to form a ring containing a Si atom to which they bond; g is an integer of 1 to 2; and f is an integer of 1 to 10, and

wherein in formula (2), R 1 , R 2 , R 3 , R 4 , R 5 and R 6 have the same definitions as given above; and e is an integer of 1 to 2.

7. The method according to claim 1 , wherein the reaction is conducted by adding water.

8. The method according to claim 1 , wherein the ratio of the total mols of chlorine atoms of the metal halogen compound is from 2.1 to 4.1 times of the total mols of the organic group contained in the organic lithium.