Composite reinforcement
Composite reinforcer (R- 2 ) self-adhesive, by curing, to a diene rubber matrix, which can be used as reinforcing element for a tire, comprising: one or more reinforcing thread(s) ( 20 ), for example a carbon steel cord; a first layer ( 21 ) of a thermoplastic polymer, the glass transition temperature of which is positive, for example, a polyamide 6,6, covering individually said thread or each thread or collectively several threads; a second layer ( 22 ) comprising a functionalized diene elastomer bearing functional groups selected from epoxide, carboxyl, acid anhydride and acid ester groups, for example, an epoxidized natural rubber, covering the first layer ( 21 ). Process for manufacturing such a composite reinforcer and rubber article or semi-finished product, especially a tire, incorporating such a composite reinforcer.
1. A composite reinforcer comprising:
one or more reinforcing thread(s);
a first layer of a thermoplastic polymer, the glass transition temperature of which is positive, covering said thread, individually each thread or collectively several threads; and
a second layer consisting of a functionalized diene elastomer bearing functional groups selected from epoxide, carboxyl, acid anhydride and acid ester groups, covering the first layer.
2. The reinforcer according to claim 1 , wherein the glass transition temperature of the thermoplastic polymer is greater than +20° C.
3. The reinforcer according to claim 1 , wherein the thermoplastic polymer is an aliphatic polyamide or a polyester.
4. The reinforcer according to claim 3 , wherein the thermoplastic polymer is a polyamide 6,6.
5. The reinforcer according to claim 1 , wherein the diene elastomer is selected from the group consisting of natural rubber, synthetic polyisoprenes, polybutadienes, butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
6. The reinforcer according to claim 1 , wherein the diene elastomer is an epoxidized diene elastomer.
7. The reinforcer according to claim 6 , wherein the diene elastomer is a natural rubber or a synthetic polyisoprene.
8. The reinforcer according to claim 6 , wherein the diene elastomer is a polybutadiene or a butadiene/styrene copolymer.
9. The reinforcer according to claim 1 , wherein the minimum thickness of the first layer is between 1 μm and 2 mm.
10. The reinforcer according to claim 1 , wherein the minimum thickness of the second layer lies in the range from 0.02 μm to 10 μm.
11. The reinforcer according to claim 1 , wherein the reinforcing thread is made of metal.
12. The reinforcer according to claim 11 , wherein the metal wire is a carbon steel wire.
13. A rubber article or semi-finished product comprising a composite reinforcer according to claim 1 .
14. A pneumatic tire comprising a composite reinforcer according to claim 1 .
15. A process for manufacturing a composite reinforcer according to claim 1 , comprising the steps of:
the reinforcing thread or each reinforcing thread is covered individually, or several reinforcing threads are covered collectively by a first layer of the thermoplastic polymer having a positive glass transition temperature;
a second layer comprising the functionalized diene elastomer bearing functional groups selected from epoxide, carboxyl, acid anhydride and acid ester groups, is deposited on the first layer; and
the assembly undergoes a thermo-oxidative treatment.
16. The process according to claim 15 , wherein the glass transition temperature of the thermoplastic polymer is above +20° C.
17. The process according to claim 15 , wherein the thermoplastic polymer is an aliphatic polyamide or a polyester.
18. The process according to claim 15 , wherein the diene elastomer is selected from the group consisting of natural rubber, synthetic polyisoprenes, polybutadienes, butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
19. The process according to claim 15 , wherein the diene elastomer is an epoxidized diene elastomer.
20. The process according to claim 19 , wherein the diene elastomer is a natural rubber or a synthetic polyisoprene.
21. The process according to claim 19 , wherein the diene elastomer is a polybutadiene or a butadiene/styrene copolymer.
22. The process according to claim 15 , which further includes a final step of crosslinking the composite reinforcer.