Conjugated diene copolymer and method for manufacturing conjugated diene copolymer
A conjugated diene copolymer has a covalent bond reversibly dissociated and added by heat, and has at least two peaks in each of curves of molecular weight distributions measured at 40° C. and 60° C. by gel permeation chromatography, wherein a change rate of the proportion of the area of the peak having the lowest molecular weight in measurement at 60° C. to the proportion of the area of the peak having the lowest molecular weight in measurement at 40° C.
1. A conjugated diene copolymer having a structure represented by the following formula (1):
wherein in the formula (1), m represents an integer of 0 to 30, P 1 , P 2 , P 3 , and P 4 represent a polymer chain containing conjugated diene units, c1, c2, c3, and c4 each independently represent an integer of 0 to 3, c1+c2+c3+c4 is 1 or more, R 1 , R 2 , R 3 , and R 4 represent a hydrocarbyl group optionally having a substituent or R 1 and R 2 and/or R 3 and R 4 are bonded to represent a hydrocarbylene group or an aromatic heterocyclic ring optionally having at least one atom selected from the group consisting of a silicon atom, a nitrogen atom, and an oxygen atom, and L 1 , L 2 , L 3 , and L 4 represent a hydrogen atom or any bonding group, with the proviso that at least one of L 1 , L 2 , L 3 and L 4 represents a bonding group, the bonding group represents a structure obtained by a reaction of a functional group reactive with a conjugated diene copolymer having an active terminal, and the functional group is selected from the group consisting of a glycidyl ether group, an alkoxy group, a phenoxy group, a benzyloxy group, an alkoxysilyl group, and a halogen group.
2. The conjugated diene copolymer according to claim 1 , having a cyclic structure in which R 1 and R 2 are bonded and a cyclic structure in which R 3 and R 4 are bonded in the formula (1).
3. A method for manufacturing a conjugated diene copolymer according to claim 1 , the method comprising:
a step of polymerizing a monomer containing a conjugated diene compound in a hydrocarbon solvent in the presence of a polymerization initiator to yield a conjugated diene copolymer having an active terminal; and
a step of reacting the conjugated diene copolymer having an active terminal with a compound having a covalent bond reversibly dissociated and added by heat to yield a conjugated diene copolymer having the covalent bond, wherein the compound is a compound represented by the following formula (2)
wherein in the formula (2), m represents an integer of 0 to 30, R 1 , R 2 , R 3 , and R 4 represent a hydrocarbyl group optionally having a substituent or R 1 and R 2 and/or R 3 and R 4 are bonded to represent a hydrocarbylene group or an aromatic heterocyclic ring optionally having at least one atom selected from the group consisting of a silicon atom, a nitrogen atom, and an oxygen atom, and at least one Y 1 , Y 2 , Y 3 , and Y 4 represents a functional group reactive with a diene copolymer having an active terminal, the remaining Y 1 , Y 2 , Y 3 , and Y 4 groups representing a hydrogen atom, and
wherein the functional group is selected from the group consisting of a glycidyl ether group, an alkoxy group, a phenoxy group, a benzyloxy group, an alkoxysilyl group, and a halogen group.
4. The method for manufacturing a conjugated diene copolymer according to claim 3 , further comprising a step of reacting the conjugated diene copolymer having an active terminal with a modifier containing a heteroatom to introduce a unit based on the modifier into the conjugated diene copolymer.
5. The method for manufacturing a conjugated diene copolymer according to claim 3 , wherein a modifier containing a heteroatom is added in the step of yielding the conjugated diene copolymer having an active terminal.
6. The conjugated diene copolymer according to claim 1 , further having a unit based on a modifier containing a heteroatom.
7. The conjugated diene copolymer according to claim 2 , further having a unit based on a modifier containing a heteroatom.
8. The method for manufacturing a conjugated diene copolymer according to claim 4 , wherein a modifier containing a heteroatom is added in the step of yielding the conjugated diene copolymer having an active terminal.