Method for synthesizing a thermoplastic elastomer comprising at least one poly(α-methylstyrene) block

Patent metadata

Field	Value
Publication number	US-10889676-B2
Application number	US-201616063988-A
Country	US
Kind code	B2
Filing date	Dec 8, 2016
Priority date	Dec 21, 2015
Publication date	Jan 12, 2021
Grant date	Jan 12, 2021

Abstract

A method for synthesizing a thermoplastic elastomer comprising at least one polydiene block and at least one other poly(α-methylstyrene) block comprises:
polymerizing at least one diene monomer in a starting reaction medium comprising an anionic polymerization initiator and an aprotic non-polar solvent; polymerizing α-methylstyrene to the living polydiene chain obtained in the preceding step comprising: maintaining the reaction medium containing the living diene elastomer obtained previously and α-methylstyrene at a positive temperature, below the ceiling temperature for the polymerization of α-methylstyrene; cooling the reaction medium obtained at the end of step a., to a temperature below 0° C.; simultaneously, successively or prior to the cooling step, adding a purified aprotic polar solvent to the reaction medium with a volume ratio of the polar solvent to the non-polar solvent of less than 1; and propagating the polymerization of α-methylstyrene to the living polydiene chain.

First claim

The invention claimed is:

1. A method for synthesizing a thermoplastic elastomer comprising at least one polydiene block and at least one other poly(α-methylstyrene) block, wherein the method comprises the following steps:
1. polymerizing at least one diene monomer in a starting reaction medium comprising an anionic polymerization initiator and an aprotic non-polar solvent to obtain a living polydiene chain;
2. polymerizing α-methylstyrene to the living polydiene chain obtained in the preceding step comprising:
a. at the end of the polymerization of step 1., maintaining a reaction medium containing the living polydiene chain obtained previously and α-methylstyrene at a temperature above 20° C. and below the ceiling temperature for the polymerization of α-methylstyrene for at least one minute;
b. cooling the reaction medium obtained at the end of the preceding step a., to a temperature below 0° C.;
c. simultaneously, successively or prior to the cooling step, adding a purified aprotic polar solvent to the reaction medium with a volume ratio of the polar solvent to the non-polar solvent of less than 1; and
d. propagating the polymerization of α-methylstyrene to the living polydiene chain;

3. terminating the polymerization and recovering the thermoplastic polymer.

2. A method according to claim 1 , wherein the diene monomer is butadiene.

3. A method according to claim 1 , wherein, during step 1, the diene monomer is copolymerized with another monomer.

4. A method according to claim 3 , wherein the other monomer is styrene.

5. A method according to claim 1 , wherein the anionic polymerization initiator is an organometallic compound comprising at least one carbon-alkali metal bond.

6. A method according to claim 1 , wherein the anionic polymerization initiator is monofunctional.

7. A method according to claim 1 , wherein the anionic polymerization initiator is polyfunctional.

8. A method according to claim 7 , wherein the anionic polymerization initiator is bifunctional.

9. A method according to claim 8 , wherein the anionic polymerization initiator is 1,3-diisopropylbenzenedilithium.

10. A method according to claim 1 , wherein the α-methylstyrene is a purified α-methylstyrene monomer that is added to the reaction medium at the end of the polymerization of at least one diene monomer of step 1.

11. A method according to claim 1 , wherein, in step 2.a., the reaction medium comprising the living polydiene is maintained at ambient temperature in the presence of α-methylstyrene.

12. A method according to claim 1 , wherein the cooling of step 2.b. is carried out at a temperature ranging from −10° C. to −40° C.

13. A method according to claim 1 , wherein the aprotic polar solvent is selected from thioethers and ethers.

14. A method according to claim 13 , wherein the aprotic polar solvent is tetrahydrofuran.

15. A method according to claim 1 , wherein the purified aprotic polar solvent is introduced into the reaction medium before the cooling step.

16. A method according to claim 1 , wherein the purified aprotic polar solvent is introduced into the reaction medium after the cooling step.

17. A method according to claim 1 , wherein the volume ratio of the polar solvent to the non-polar solvent is less than 1/3.

18. A method according to claim 1 , wherein, during step 2, the α-methylstyrene monomer is copolymerized with another monomer.

19. A method according to claim 1 , wherein at the end of the polymerization of step 1, the reaction medium containing the living diene elastomer and α-methylstyrene is maintained at a temperature above 20° C. and below the ceiling temperature for at least fifteen minutes for the polymerization of α-methylstyrene.

20. A method according to claim 1 , wherein at the end of the polymerization of step 1, the reaction medium containing the living diene elastomer and α-methylstyrene is maintained at a temperature above 20° C. and below the ceiling temperature for at least one hour for the polymerization of α-methylstyrene.

Assignees

• Michelin & Cie

Inventors

• Matmour Rachid
• Ngo Robert

Classifications

• C08F136/06

  Butadiene · CPC title

• C08F297/04 Primary

  polymerising vinyl aromatic monomers and conjugated dienes · CPC title

• C08F297/042

  using a polyfunctional initiator · CPC title

• B60C1/00

  Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition · CPC title

• C08K5/56

  Organo-metallic compounds, i.e. organic compounds containing a metal-to-carbon bond · CPC title