Rubber composition containing a modified elastomer, method for preparing same, and tire containing same
View Patent ↗The invention relates to a rubber composition based on at least one diene elastomer, a reinforcing filler, a chemical crosslinker and a modifier selected from compounds comprising at least one group Q, and at least one group A, which are joined to one another by at least one and preferably one spacer group Sp, wherein: Q comprises a dipole containing at least one and preferably one nitrogen atom, A comprises an associative group comprising at least one nitrogen atom, Sp is an atom or group of atoms forming a bond between Q and A. This composition has an improved balance between stiffness under moderate deformations/elongation at break and improved hysteresis properties and is therefore especially suited to the manufacture of tires for enhancing the trade off between rolling resistance and resistance to large deformations.
1. A rubber composition based on at least one diene elastomer, a reinforcing filler, a chemical crosslinker and a modifier, optionally already grafted onto the elastomer, selected from compounds comprising at least one group Q, and at least one group A, which are joined to one another by at least one spacer group Sp, wherein:
Q comprises a dipole containing at least one nitrogen atom,
A comprises an associative group comprising at least one nitrogen atom, wherein A is selected from imidazolidinyl, triazolyl, triazinyl, bis-ureyl, and ureido-pyrimidyl groups
Sp is an atom or group of atoms forming a bond between Q and A.
2. The composition according to claim 1 , wherein the group A conforms to one of the formulae (II) to (VI) below:
where:
R denotes a hydrocarbon group optionally containing heteroatoms,
X denotes an oxygen or sulphur atom.
3. The composition according to claim 1 , wherein Q comprises a nitrile oxide, nitrone or imine nitrile function.
4. The composition according to claim 1 , wherein the group Q is a group of formula (VII), (VIII) or (IX) below:
in which R 1 to R 6 are selected independently from a spacer group Sp, a hydrogen atom, a linear or branched C 1 -C 20 alkyl group, a linear or branched C 3 -C 20 cycloalkyl group, a linear or branched C 6 -C 20 aryl group and a group of formula (X)
wherein n represents 1, 2, 3, 4 or 5, and each Y represents independently a spacer group Sp, an alkyl group, or a halide.
5. The composition according to claim 1 , wherein the spacer group is a C 1 -C 24 linear or branch alkyl chain, optionally comprising one or more heteroatoms selected from nitrogen, sulphur, silicon or oxygen atoms.
6. The composition according to claim 1 , wherein the group Q is a group of formula (XIa) or (XIb):
wherein R 7 and R 8 represent independently a hydrogen or a C 1 -C 5 alkyl group, an alkoxy, or a halide, R 3 is selected independently from a spacer group Sp, a hydrogen atom, a linear or branched C 1 -C 20 alkyl group, a linear or branched C 3 -C 20 cycloalkyl group, a linear or branched C 6 -C 20 aryl group and a group of formula (X)
wherein n represents 1, 2, 3, 4 or 5 and each Y represents independently a spacer group Sp, an alkyl group or a halide, and the group A is a group of formula (XII)
7. The composition according to claim 1 , wherein the modifier is selected from the compounds of formula (XIII) to (XXI) below:
where R 3 is selected from a spacer group Sp, a hydrogen atom, a linear or branched C 1 -C 20 alkyl group, a linear or branched C 3 -C 20 cycloalkyl group, a linear or branched C 6 -C 20 aryl group and a group of formula (X)
wherein n represents 1, 2, 3, 4 or 5, and each Y represents independently a spacer group Sp, an alkyl group, or a halide
8. The composition according to claim 1 , wherein the modifier is selected from the compounds of formula (XXII) and (XXIII) below:
9. The composition according to claim 1 , wherein the diene elastomer is a substantially unsaturated diene elastomer selected from natural rubber, synthetic polyisoprenes, polybutadienes, butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
10. The composition according to claim 1 , wherein the diene elastomer is a substantially saturated elastomer selected from butyl rubbers and the copolymers of dienes and alpha-olefins such as EPDMs.
11. The composition according to claim 1 , wherein the chemical crosslinker comprises 0.5 to 12 phr of sulphur, or 1 to 10 phr of sulphur, or 0.01 to 10 phr of one or more peroxide compounds.
12. The composition according to claim 1 , wherein the proportion of modifier varies from 0.01 to 50 mol %, or from 0.01 mol % to 5 mol %.
13. A tire comprising a rubber composition as described in claim 1 .
14. The composition according to claim 5 , wherein the spacer group is a C 1 -C 10 linear or branched alkyl chain optionally comprising one or more heteroatoms selected from nitrogen, sulphur, silicon, or oxygen atoms.
15. The composition according to claim 6 , wherein R 7 and R 8 represent independently a C 1 -C 5 alkyl group or a halide.
16. The composition according to claim 15 , wherein R 7 and R 8 represent independently a methyl group or a chlorine atom.
17. The composition according to claim 1 , wherein there is one spacer group Sp.
18. The composition according to claim 1 , wherein Q comprises a dipole containing one nitrogen atom.
19. The composition according to claim 2 , wherein X denotes an oxygen atom.