RUBBER COMPOSITION FOR INNER LINER

Abstract

The present invention relates to a cross-linkable rubber composition, the cross-linkable rubber composition comprising a halogenated butyl rubber, a filler, and a resin. The resin is a terpolymer of ethylene, acrylic ester and maleic anhydride and is present in an amount ranging from ≥1 to ≤20 phr.

Claims

1. A cross-linkable rubber composition, the cross-linkable rubber composition comprising: a halogenated butyl rubber, a filler, and a resin, wherein the resin is a terpolymer of ethylene, acrylic ester and maleic anhydride and is present in an amount ranging from ≥1 to ≤20 phr.

2. The rubber composition according to claim 1, wherein the halogenated butyl rubber is selected from chlorinated butyl rubber or brominated butyl rubber.

3. The rubber composition according to claim 1, wherein the halogenated butyl rubber is present in an amount of at least 60 phr.

4. The rubber composition according to claim 1, wherein the composition further comprises a natural rubber.

5. The rubber composition according to claim 1, wherein the natural rubber is present in an amount of ≤40 phr.

6. The rubber composition according to claim 1, wherein the filler is or comprises a reinforcing filler selected from carbon black or silica.

7. The rubber composition according to claim 6, wherein the filler further comprises a non-reinforcing filler selected from the group of china clay, talc and rice husk.

8. The rubber composition according to claim 1, wherein the composition comprises a syndiotactic 1,2-polybutadiene.

9. The rubber composition according to claim 8, wherein the syndiotactic 1,2-polybutadiene is present in an amount ranging from ≥5 to ≤20 phr.

10. The rubber composition according to claim 1, wherein the terpolymer of ethylene, acrylic ester and maleic anhydride is present in an amount in a range of ≥5 to ≤15 phr.

11. A cross-linked rubber composition, is-obtained by cross-linking a rubber composition according to claim 1.

12. The cross-linked rubber composition according to claim 11 with an air permeability (determined according to ISO 2393) ranging from ≥40 am.sup.2/Pas to ≤60 am.sup.2/Pas or from ≥30 am.sup.2/Pas to ≤40 am.sup.2/Pas.

13. The cross-linked rubber composition according to claim 11 with a rebound value ranging from 31% to 44%.

14. A method of preparing a tyre, comprising the steps of: providing a tyre assembly comprising a cross-linkable rubber composition according to claim 1; and cross-linking at least the cross-linkable rubber composition in the tyre assembly.

15. A tyre comprising an inner liner, wherein the inner liner comprises a cross-linked rubber composition according to claim 11.

16. The rubber composition according to claim 6, wherein the reinforcing filler is present in an amount ranging from ≥40 to ≤70 phr.

17. The rubber composition according to claim 7, wherein the non-reinforcing filler is present in an amount ranging from ≥10 to ≤30 phr

Description

EXAMPLE 1

[0043] The table below shows compositions using only bromobutyl rubber as the rubber component. Amounts for the components are given in PHR. The rubber composition R is a reference composition. The composition according to the invention I1 is a composition with a higher amount of RAE process oil along with the terpolymer of ethylene, acrylic ester and maleic anhydride (Lotader®) and the composition I2 is a composition with the same amount of RAE process oil with lower Carbon black as the reference and the terpolymer of ethylene, acrylic ester and maleic anhydride (Lotader®) according to the invention.

TABLE-US-00001 Reference R1 amount I1 amount I2 amount Components (PHR) (PHR) (PHR) Bromobutyl rubber 100 100 100 RAE Process oil, Free of 8 10 8 labeling N660 GPF Carbon Black 60 60 50 China Clay - 8 m2/g Sulphur Soluble Fg No. 1 0.4 0.4 0.4 0.5% Oil Based MBTS 1.3 1.3 1.3 DCBS Zinc Oxide 2.75 2.75 2.75 Stearic Acid (Flake Form) 2 2 2 Struktol 40MS (Flake 4 4 4 Form) Aliphatic Resin 5 Phenol Formaldehyde 3 3 Resin Lotader 10 10

[0044] Mercaptobenzothiazole Sulfenamide (MBTS) is used as an accelerator 1.

[0045] Dicyclohexyl benzothiazole sulfenamide (DCBS) is used as an accelerator 2.

[0046] Struktol 40MS is a hydrocarbon blend and used as a process aid.

[0047] The following table shows the results obtained from the cured rubber compositions:

TABLE-US-00002 Result R1 I1 I2 Hardness (median) °Sh A 48.80 55.10 50.30 Air Permeability am.sup.2/Pas 42.96 47.39 45.87 Payne Effect G′0.56 0.38 0.31 0.23 (100° C.) Rebound (70° C.) % 28.80 35.00 36.50

[0048] A higher rebound value suggests that the compound have lower damping property and better rolling resistance.

[0049] A lower value of G′ at 0.56 strain hints to less filler-filler interaction and therefore depicts lower hysteresis property of the compound.

[0050] As can be taken from the results above, the addition of Lotader resulted in an increase in the results for air impermeability value. Higher air impermeability value indicates less air retention.

[0051] Furthermore, addition of Lotader to the composition increases the hardness of the compound I1 and I2 with respect to reference R1.

EXAMPLE 2

[0052] The table below shows the composition I3 in comparison to a composition I4 with the terpolymer of ethylene, acrylic ester and maleic anhydride (Lotader®) using a natural rubber as second rubber component. Amounts for the components are given in PHR.

TABLE-US-00003 Reference R2 amount I3 amount I4 amount Components (PHR) (PHR) (PHR) TSR 20 15 15 15 Bromobutyl rubber 85 85 85 RAE Process oil, Free of 6 6 5 labeling N660 GPF Carbon Black 60 60 50 China Clay - 8 m2/g 20 20 20 Sulphur Soluble Fg No. 1 0.5 0.5 0.5 0.5% Oil Based MBTS 1 1 1 DCBS 1 1 1 Zinc Oxide 3 3 3 Stearic Acid (Flake Form) 1 1 1 Struktol 40MS (Flake 5 5 5 Form) Koresin 3 3 3 Lotader 10 10

[0053] The following table shows the results obtained from the cured rubber compositions:

TABLE-US-00004 Result R2 I3 I4 Hardness (median) °Sh A 58.50 63.10 60.90 Air Permeability am.sup.2/Pas 57.12 59.41 58.03 Payne Effect G′0.56 0.49 0.42 0.32 (100° C.) Rebound (70° C.) % 33.90 39.40 41.00

[0054] As can be seen from this table, a small amount of natural rubber added to the composition comprising Lotader® terpolymer improved the rolling resistance.

[0055] Such cross-linked rubber compositions are particularly usable for manufacturing a tyre inner liner.

EXAMPLE 3

[0056] The table below shows the composition I5 and I6 in comparison to a reference composition R3. The composions I5 and I6 comprise the terpolymer of ethylene, acrylic ester and maleic anhydride (Lotader®) and a syndiotactic 1,2-polybutadiene. Amounts for the components are given in PHR.

TABLE-US-00005 Reference R3 amount I5 amount I6 amount Components (PHR) (PHR) (PHR) Bromobutyl rubber 100 100 100 N-660 (GPF) Carbon Black 50 50 40 Stearic acid, Rubber grade 1 1 1 China Clay 20 20 20 Sulphur (Soluble, 1% Oil 0.40 0.40 0.40 treated) Polyterpene Resin 7 7 7 Zinc Oxide 2 2 2 MBTS 0.9 0.9 0.9 (Mercaptobezothiazole Disulfide) LOTADER ® 3430 resin — 10 10 AT 400 10 10 10

[0057] The syndiotactic 1,2-polybutadiene was AT 400 syndiotactic 1,2-butadiene supplied by JSR Corporation.

[0058] The following table shows the results obtained from the cured rubber compositions of R3, I5 and I6:

TABLE-US-00006 Result R3 I5 I6 Hardness (median) °Sh A 61.50 69.70 65.40 Air Permeability am.sup.2/Pas 28.08 30.28 31.34 rubber 20′ at 160° C. Payne Effect G′0.56 0.43 0.39 0.30 (100° C.) Rebound (70° C.) % 36.50 39.40 41.70

[0059] As can be seen from this table, results for air permeability were improved for the rubber composition when a syndiotactic 1,2-butadiene rubber was added to the composition comprising Lotader® terpolymer. This is particularly usable for manufacturing a tyre inner liner.