Process for preparing a diene copolymer comprising a polyether block, diene copolymer comprising a polyether block, reinforced rubber composition and tire
View Patent ↗A process for preparing, in one step, a diene block copolymer, of which at least one of these blocks is constituted of a polyether, the number-average molecular weight of which is approximately from 100 to 5000 g/mol, and at least one other of these blocks is constituted of a diene elastomer. The process according to the invention allows a high degree of grafting of the polyether to the polymer chains. Also disclosed is a reinforced rubber composition, especially intended for the manufacture of tires, comprising such a block copolymer which is intended to interact with the reinforcing filler. Such a rubber composition has improved hysteresis properties in the vulcanized state, while retaining satisfactory processing properties in the non-vulcanized state.
1. A process for preparing a block copolymer, of which at least one of said blocks is constituted of a diene elastomer and at least another of said blocks is constituted of a polyether, wherein the process comprises a step of reacting a living diene elastomer with a functionalizing agent of general formula I having a functional polyether block of number-average molecular weight approximately from 100 to 5000 g/mol,
in which:
R 1 represents a saturated aliphatic hydrocarbon radical of valence m having 1 to 15 carbon atoms, an unsubstituted aromatic hydrocarbon radical of valence m having 6 to 15 carbon atoms or an aryl-substituted saturated aliphatic hydrocarbon radical of valence m having 7 to 15 carbon atoms;
R 2 represents a C 1 -C 10 alkylene radical;
n is an integer from 2 to 60;
m is an integer from 1 to 4; and
wherein the living diene elastomer is obtained by anionic polymerization using an organolithium initiator.
2. The process according to claim 1 , wherein in the general formula I, m is equal to 2.
3. The process according to claim 1 , wherein in the general formula I, R 2 represents the
radical, in which R 3 and R 4 are, independently of one another, a hydrogen atom or a C i -C 4 alkyl radical.
4. The process according to claim 3 , wherein in the general formula I, R 2 represents the ethylene radical.
5. The process according to claim 4 , wherein the functionalizing agent of general formula I is polyethylene glycol diglycidyl ether.
6. The process according to claim 1 , wherein prior to the step of reacting a living diene elastomer with a functionalizing agent of general formula I, the process comprises a step of preparing the living polymer by anionic polymerization of at least one diene monomer in the presence of a monofunctional organolithium initiator.
7. The process according to claim 1 , further comprising a step of coupling and/or of star-branching and/or else of supplementary functionalization with a functionalizing agent different from that of general formula I.
8. A diene block copolymer, of which at least one of said blocks is constituted of a diene elastomer and at least another of said blocks is constituted of a polyether of number-average molecular weight approximately from 100 to 5000 g/mol, obtained by the process according to claim 1 .
9. The diene block copolymer according to claim 8 , comprising three blocks, the block constituted of a polyether being located in the middle of the polymer chain between two blocks constituted of a diene elastomer.
10. The diene block copolymer according to claim 8 , wherein the diene elastomer is a styrene/butadiene copolymer.
11. A reinforced rubber composition, for use in the manufacture of a pneumatic tire, based on at least one diene block copolymer obtained according to the process of claim 1 and adapted to interact with the reinforcing filler.
12. The rubber composition according to claim 11 , comprising predominantly a reinforcing inorganic filler as a reinforcing filler.
13. The rubber composition according to claim 12 , wherein the reinforcing filler is constituted by the reinforcing inorganic filler.
14. The rubber composition according to claim 12 , wherein the reinforcing inorganic filler is silica.
15. The rubber composition according to claim 11 , wherein the reinforcing filler comprises carbon black.
16. The rubber composition according to claim 11 , comprising, as a blend with said diene block copolymer, at least one of the polymers chosen from natural rubber, synthetic diene elastomers, synthetic diene elastomers that are coupled and/or star-branched and/or partially or completely functionalized by a functionalizing agent different from that represented by the general formula I, and synthetic elastomers other than diene elastomers.
17. A tire, incorporating, in at least one of its constituent components, a rubber composition according to claim 11 .
18. A tread for a tire wherein the tire and the tread comprise a rubber composition according to claim 11 .