Process for producing aromatic vinyl/conjugated diene copolymer and product of hydrogenation thereof
As a method for producing a copolymer with a high oil absorption rate by separating a solvent from a copolymer solution containing a copolymer in a simple manner with a less energy consumption, the present invention relates to a production method for obtaining a copolymer by separating a solvent from a copolymer solution, the method including the following Steps A to C. Step A: a step of regulating a solid component concentration (Ts) of the copolymer solution to a range of (5≤Ts≤60) in terms of a mass %, Step B: a step of heating the copolymer (P) solution obtained in the Step A such that a temperature T (° C.) is in a specified range, and Step C: a step of discharging the copolymer solution heated in the Step B from a specified nozzle at a linear velocity of 1 to 100 m/sec to separate the solvent in an inert gas stream at 0 to 200° C.
1. A method for producing a copolymer (P), comprising separating a solvent contained in a copolymer (P) solution to obtain the copolymer (P),
the copolymer (P) being at least one copolymer selected from the group consisting of an aromatic vinyl compound-conjugated diene copolymer comprising at least one conjugated diene and at least one aromatic vinyl compound and having a weight average molecular weight of 10,000 to 1,000,000, a hydride of the copolymer, and a mixture thereof;
the solvent being a saturated aliphatic hydrocarbon solvent or a saturated alicyclic hydrocarbon solvent each having a boiling point of 30 to 100° C.,
the method comprising:
regulating a solid component concentration (Ts) of the copolymer (P) solution to a range of (5≤Ts≤60) in terms of a mass %;
heating the copolymer (P) solution obtained in the regulating such that a temperature T (° C.) is in a range of {(225−1.9×Ts)≤T≤(310−1.9×Ts)}; and
discharging the copolymer (P) solution heated in the heating from any one nozzle selected from a rotary wheel atomizer, a two-fluid nozzle atomizer, and a pressure nozzle atomizer at a linear velocity of 1 to 100 m/sec to separate the solvent in an inert gas stream at 0 to 200° C.
2. The method according to claim 1 , wherein the copolymer (P) is at least one copolymer selected from the group consisting of a block copolymer comprising a polymer block (b) comprising at least one conjugated diene unit and a polymer block (a) comprising at least one aromatic vinyl compound unit, a hydride of the block copolymer, and a mixture thereof.
3. The method according to claim 1 , wherein the copolymer (P) is one produced by liquid phase anionic polymerization with an organic alkali metal compound.
4. The method according to claim 1 , wherein a molar weight distribution of the copolymer (P) is in a range of 1.0 to 2.5.
5. The method according to claim 1 , wherein the solvent is at least one selected from the group consisting of isopentane, pentane, cyclopentane, hexane, cyclohexane, isoheptane, and heptane.
6. The method according to claim 1 , wherein the temperature T (° C.) in the heating is in a range of 200 to 275° C.
7. The method according to claim 1 , wherein the solid component concentration (Ts) of the copolymer (P) solution in the regulating is (10≤Ts ≤35) in terms of a mass %.
8. The method according to claim 1 , wherein the linear velocity in the discharging is from 5 to 50 m/sec.
9. The method according to claim 1 , wherein the temperature of the inert gas in the discharging is from 10 to 120° C.
10. The method according to claim 1 , wherein an amount of the inert gas in the discharging is from 0.01 to 5.0 NL relative to 1 kg of the copolymer (P) solution.
11. The method according to claim 1 , wherein the copolymer (P) obtained through the discharging is a fibrous copolymer.
12. The method according to claim 1 , wherein an amount of the residual solvent in the copolymer (P) obtained through the discharging is 2 mass % or less.
13. The method according to claim 1 , wherein a bulk density of the copolymer (P) obtained through the discharging is from 0.02 to 0.20 g/mL, and an oil absorption rate thereof is from 10 to 50 g/g.