Process for radical grafting of a diene elastomer

Patent metadata

Field	Value
Publication number	US-9487614-B2
Application number	US-201314653337-A
Country	US
Kind code	B2
Filing date	Dec 17, 2013
Priority date	Dec 20, 2012
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

A process for the radical grafting of a graft to a diene elastomer, comprising the following stages:
a. dissolving, with stirring, at least one diene elastomer and at least one thiol derivative as graft in a solvent comprising a mixture of at least one polar solvent and at least one nonpolar solvent, b. heating the homogeneous reaction mixture obtained in the preceding stage to the temperature of the grafting reaction, and c. once the temperature of the grafting reaction has been reached, adding the radical initiator in order to bring about the grafting of the graft to the units of the elastomer comprising unsaturations.

This radical grafting process makes it possible to achieve high grafting yields which can reach 100%.

First claim

The invention claimed is:

1. A process for the radical grafting of a graft to a diene elastomer, comprising the following stages:
a) dissolving, with stirring, at least one diene elastomer and at least one thiol derivative as graft in a solvent comprising a mixture of at least at least one polar solvent and at least one nonpolar solvent,
b) heating the homogeneous reaction mixture obtained in the preceding stage to the temperature of the grafting reaction, and
c) once the temperature of the grafting reaction has been reached, adding the radical initiator in order to bring about the grafting of the graft to the units of the elastomer comprising unsaturations, and wherein the solvent of the mixture in stage c) comprises at least 4% by volume and at most 60% by volume of the at least one polar solvent with respect to the volume of the at least one nonpolar solvent.

2. The process for the radical grafting of a graft to a diene elastomer according to claim 1 , wherein the polar solvent is selected from the group consisting of nitrogenous solvents, ketones, sulphoxides, ethers, halogenated solvents, and mixtures of these solvents.

3. The process for the radical grafting of a graft to a diene elastomer according to claim 2 , wherein the polar solvent is dichloromethane or tetrahydrofuran.

4. The process for the radical grafting of a graft to a diene elastomer according to claim 1 , wherein the thiol derivative is chosen from the compounds of following formula (1):
HS—R1-X  Formula (1)

wherein: R1 denotes a C1-C36 alkanediyl, C5-C15 cycloalkanediyl, C6-C15 arenediyl or C7-C15 alkanediyl group, it being possible for these groups to be halogenated or nonhalogenated,
X denotes a C1-C50 alkyl, C5-C50 cycloalkyl, C6-C50 aryl or C7-C50 arylalkyl group, a halogen atom, a hydrocarbon group comprising at least one heteroatom selected from the group consisting of O, N, P, S and Si, or a monovalent polymer chain.

5. The process for the radical grafting of a graft to a diene elastomer according to claim 4 , wherein the thiol derivative is selected from the group consisting of 2-mercaptoethanol, dodecanethiol, 4-cyanobutanethiol, cysteamine, mercapto-1-decanoic acid, 4-mercaptobutyric acid, ethyl thioglycolate, 3-chloro-1-propanethiol, methyl 3-mercaptopropionate, benzyl mercaptan, 3-dimethylamino-1-propanethiol, 3-methoxy-1-propanethiol, and 2-(2-oxiranylmethoxy)ethanethiol.

6. The process for the radical grafting of a graft to a diene elastomer according to claim 1 , wherein the thiol derivative and the radical initiator are present in a molar ratio that is at least 12, and at most 96.

7. The process for the radical grafting of a graft to a diene elastomer according to claim 1 , wherein the diene elastomer is chosen from elastomers exhibiting a content by weight of vinyl units in the diene part of greater than 20%.

8. The process for the radical grafting of a graft to a diene elastomer according to claim 1 , wherein the diene elastomer is a polybutadiene (BR), a synthetic polyisoprene (IR), a natural rubber (NR), or a copolymer of butadiene and/or of isoprene.

9. The process for the radical grafting of a graft to a diene elastomer according to claim 1 , wherein the amounts of grafts to the vinyl units resulting from the conjugated diene(s) of the diene elastomer are present in a molar ratio that is at least 0.1%, and is at most 80%.

10. The process for the radical grafting of a graft to a diene elastomer according to claim 1 , wherein the solvent of the reaction medium in stage c) comprises at most 40% by volume of the at least one polar solvent with respect to the volume of the at least one nonpolar solvent.

11. The process for the radical grafting of a graft to a diene elastomer according to claim 6 , wherein the molar ratio of the thiol derivative to the radical initiator is at least 24 and at most 48.

12. The process for the radical grafting of a graft to a diene elastomer according to claim 7 , wherein the diene elastomer is chosen from elastomers exhibiting a content by weight of vinyl units in the diene part of greater than 40%.

13. The process for the radical grafting of a graft to a diene elastomer according to claim 7 , wherein the diene elastomer is chosen from elastomers exhibiting a content by weight of vinyl units in the diene part of greater than 50%.

14. The process for the radical grafting of a graft to a diene elastomer according to claim 8 , wherein the diene elastomer is a butadiene/styrene copolymer (SBR), an isoprene/butadiene copolymer (BIR), an isoprene/styrene copolymer (SIR), or an isoprene/butadiene/styrene copolymer (SBIR).

15. The process for the radical grafting of a graft to a diene elastomer according to claim 9 , wherein the molar ratio of the amounts of grafts to the vinyl units resulting from the conjugated diene(s) of the diene elastomer is at least 0.2% and at most 60%.

16. The process for the radical grafting of a graft to a diene elastomer according to claim 9 , wherein the molar ratio of the amounts of grafts to the vinyl units resulting from the conjugated diene(s) of the diene elastomer is at least 0.3% and at most 40%.

Assignees

• Michelin & Cie
• Michelin Rech Tech

Inventors

• Matmour Rachid
• Ngo Robert
• Seeboth Nicolas

Classifications

• C08F279/02 Primary

  on to polymers of conjugated dienes · CPC title

• C08C19/20 Primary

  Incorporating sulfur atoms into the molecule · CPC title