Tire belt incorporating an antioxidant agent
View Patent ↗Tire belt comprising a rubber composition based on at least one isoprene elastomer, a reinforcing filler, a crosslinking system and an antioxidant agent, characterized in that said antioxidant agent comprises a 4,4′-bis(alkylamino)triphenylamine corresponding to the formula (I): in which R 1 and R 2 , which are identical or different, each represent a linear or branched alkyl group having from 1 to 12 carbon atoms or a cycloalkyl group having from 5 to 8 carbon atoms. Such an antioxidant gives the belt of the invention a better long-term resistance to fatigue and to crack propagation.
1. A tire belt comprising a rubber composition based on at least one isoprene elastomer, a reinforcing filler, a crosslinking system and an antioxidant agent, wherein said antioxidant agent comprises a 4,4′-bis(alkylamino)triphenylamine corresponding to the formula (I):
in which R 1 and R 2 , which are identical or different, each represent a linear or branched alkyl group having from 2 to 8 carbon atoms or a cycloalkyl group having from 5 to 8 carbon atoms;
wherein said antioxidant agent is present in an amount between 1 and 10 phr.
2. The tire belt according to claim 1 , wherein the R 1 and R 2 radicals, which are identical or different, each represent an alkyl group chosen from the group composed of isopropyl, 1,3-dimethylbutyl and 1,4-dimethylpentyl.
3. The tire belt according to claim 2 , wherein the antioxidant agent is 4,4′-bis(isopropylamino)triphenylamine corresponding to the formula (III-a):
4. The tire belt according to claim 2 , the antioxidant agent being 4,4′-bis(1,3-dimethylbutylamino)triphenylamine corresponding to the formula (III-b):
5. The tire belt according to claim 2 , wherein the antioxidant agent is 4,4′-bis(1,4-dimethylpentylamino)triphenylamine corresponding to the formula (III-c):
6. The tire belt according to claim 1 , wherein the content of antioxidant agent is between 2 and 8 phr.
7. The tire belt according to claim 1 , wherein the at least one isoprene elastomer is chosen from the group composed of natural rubber, synthetic cis-1,4-polyisoprenes and blends of these elastomers.
8. The tire belt according to claim 7 , wherein the at least one isoprene elastomer is natural rubber.
9. A method for providing anti-ageing protection to a tire belt, comprising incorporating into a rubber composition of said tire belt an antioxidant agent comprising a 4,4′-bis(alkylamino)triphenylamine corresponding to the formula (I):
wherein R 1 and R 2 , which are identical or different, each represent a linear or branched alkyl group having from 2 to 8 carbon atoms or a cycloalkyl group having from 5 to 8 carbon atoms;
wherein said antioxidant is present in an amount between 1 and 10 phr.
10. A method of manufacture or retreading of a tire, comprising introducing a tire belt according to claim 1 .
11. A tire comprising a tire belt according to claim 1 .
12. A tire according to claim 11 , wherein the tire is a heavy vehicle tyre.
13. A process for preparing a tire belt comprising a rubber composition based on at least one isoprene elastomer, a reinforcing filler, a crosslinking system and an antioxidant agent, comprising:
incorporating into an isoprene elastomer, in a mixer:
a reinforcing filler; and
an antioxidant agent,
by thermomechanically kneading the entire mixture, in one or more stages, until a maximum temperature between 110° C. and 190° C. is reached;
cooling the entire mixture to a temperature below 100° C.;
then incorporating a crosslinking system;
kneading the entire mixture up to a maximum temperature below 110° C.;
calendering or extruding the composition thus obtained in the form of a layer of rubber; and
incorporating this layer, after optional addition of textile or metallic reinforcements, into a tire belt,
wherein said antioxidant agent comprises a 4,4′-bis(alkylamino)triphenylamine corresponding to the formula (I):
wherein R 1 and R 2 , which are identical or different, each represent a linear or branched alkyl group having from 2 to 8 carbon atoms or a cycloalkyl group having from 5 to 8 carbon atoms and is present in an amount between 1 and 10 phr.
14. The tire belt according to claim 1 , wherein the content of antioxidant is between 2 and 6 phr.
15. The tire belt according to claim 4 , wherein the content of antioxidant is 3.3 phr.
16. The tire belt according to claim 4 , wherein the content of antioxidant is between 2 and 6 phr.
17. The tire belt according to claim 4 , wherein the content of antioxidant is 3.3 phr.
18. The tire belt according to claim 2 , wherein one of the R 1 and R 2 radicals is 1,3-dimethylbutyl.