RUBBER COMPOSITION FOR TYRE RIM CUSHION

Abstract

The present invention relates to a cross-linkable rubber composition, the cross-linkable rubber composition comprising a natural rubber (NR), 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 ≥5 to ≤20 phr.

Claims

1. A cross-linkable rubber composition, the cross-linkable rubber composition comprising: a natural rubber (NR), 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 ≥5 phr to ≤20 phr.

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

3. The rubber composition according to claim 1, wherein the rubber composition further comprises a butadiene rubber.

4. The rubber composition according to claim 3, wherein the butadiene rubber has a cis content in the range of ≥25 to ≤50%.

5. The rubber composition according to claim 3, wherein the butadiene rubber has a cis content in the range of ≥75 to ≤99.9%.

6. The rubber composition according to claim 1, wherein the filler is carbon black.

7. The rubber composition according to one of claim 6, wherein the carbon black is present in an amount ranging from ≥40 to ≤70 phr.

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

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

10. The cross-linked rubber composition according to claim 9 with a tan delta value at 70° C. (determined from DMA measurements according to ASTM D5963, frequency 10 Hz, 0.1% dynamic strain) of ≤0.13 and a storage modulus G′ of ≥8.5.

11. The cross-linked rubber composition according to claim 9 with a rebound value of ≥64%.

12. The cross-linked rubber composition according to claim 9, having a tensile strength according to ASTM D412 of ≥19.55 MPa.

13. The cross-linked rubber composition according to claim 9, having a payne value G′ at 0.56% strain of ≤360 kPa, the payne value being determined at a temperature of 100° C. and a frequency of 0.5 Hz.

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; cross-linking at least the cross-linkable rubber composition in the tyre assembly.

15. A tyre comprising a rim cushion, wherein the rim cushion comprises a cross-linked rubber composition according to claim 9.

Description

EXAMPLE 1

[0051] The table below shows compositions using a low cis butadiene rubber as second rubber component. Amounts for the components are given in PHR. The composition R is a reference compound. The composition C1 is a comparative example without the Lotader® resin but an amount of carbon black as low as in the composition I2. The composition I2 is a composition with the terpolymer of ethylene, acrylic ester and maleic anhydride (Lotader®) according to the invention.

TABLE-US-00002 Reference C1 (without Reference R Lotader ®) I2 amount amount amount components (PHR) (PHR) (PHR) NR (TSR 20, mooney 80) 65.00 65.00 65.00 low cis butadiene rubber 35.00 35.00 35.00 N 330 Carbon Black 63.00 58.00 58.00 Silica (semi HDS) 7.00 7.00 7.00 RAE (processing oil) 3.00 3.00 3.00 Insoluble sulphur 20% oil, 3.25 3.25 3.25 High Dispersable TBBS (N-Tert-Butyl-2 2.90 2.90 2.90 benzo-thiazole sulfenamide) Zinc oxyde (indirect) 4.00 4.00 4.00 Stearic Acid 1.50 1.50 1.50 PVI (CTP, N-(cyclohexylthio) 0.30 0.30 0.30 phthalimide) 6PPD 2.00 2.00 2.00 TMQ (Polymerized 2,2,4 tri 1.00 1.00 1.00 methyl 1,2 di hydro quinoline) Anti ozone wax 1.50 1.50 1.50 Koresin 4.00 4.00 4.00 DBD (Peptizer) 0.10 0.10 0.10 LOTADER ® 3430 resin — — 15.00

[0052] The following table shows the results obtained from the cured compositions:

TABLE-US-00003 Result R C1 I2 Hardness (median) °Sh A 68.80 67.20 73.00 Elongation at break % 271.43 289.64 367.72 Tear strength (delft) MPa 7.05 5.21 8.50 Mooney ML(1 + 1.5) 135° C. M.U. 65.60 61.50 59.60 Rebound (70° C.) % 64.30 67.90 62.30 Tan (70° C.) 0.13 0.13 0.14

[0053] The lower the Tan ∂ at 70 ° C., the lower is the hysteresis of the compound and the better for rolling resistance. A higher tensile strength of rubber compound means that the rubber compound has better mechanical property. A higher the rebound value means a compound having lower hysteresis property and better rolling resistance. A lower value G′ at 0.56 strain hints to a lower hysteresis property.

[0054] As can be seen in the result table, using the terpolymer of ethylene, acrylic ester and maleic anhydride results in an increase in hardness, an increase in elongation at break and an improvement in tear strength. Further, the Mooney value was lower, while at the same time rebound remained at the same level as the reference compound and also Tan ∂ at 70 ° C. remains the same.

EXAMPLE 2

[0055] The table below shows the composition I2 in comparison to a composition I3 with the terpolymer of ethylene, acrylic ester and maleic anhydride (Lotader®) using a high cis butadiene rubber as second rubber component. Amounts for the components are given in PHR.

TABLE-US-00004 components amount (PHR) I2 amount (PHR) I3 NR (TSR 20, mooney 80) 65.00 65.00 low cis butadiene rubber 35.00 — N 330 Carbon Black 58.00 58.00 Silica (semi HDS) 7.00 7.00 RAE (processing oil) 3.00 3.00 Insoluble sulphur 20% oil, High 3.25 3.25 Dispersable TBBS (N-Tert-Butyl-2 benzo- 2.90 2.90 thiazole sulfenamide) Zinc oxyde (indirect) 4.00 4.00 Stearic Acid 1.50 1.50 PVI (CTP, N-(cyclohexylthio) 0.30 0.30 phthalimide) 6PPD 2.00 2.00 TMQ (Polymerized 2,2,4 tri 1.00 1.00 methyl 1,2 di hydro quinoline) Anti ozone wax 1.50 1.50 Koresin 4.00 4.00 DBD (Peptizer) 0.10 0.10 High cis butadiene rubber — 35.00 LOTADER ® 3430 resin 15.00 15.00

[0056] The following table shows the results obtained from the cured compositions:

TABLE-US-00005 Result I2 I3 Hardness (median) °Sh A 73.00 73.60 Elongation at break % 367.72 352.63 Tear strength (delft) MPa 8.50 12.22 Mooney ML(1 + 1.5) 135° C. M.U. 59.60 52.40 Rebound (70° C.) % 62.30 60.00 Tan (70° C.) 0.14 0.16

[0057] As can be seen from this table, results are comparable for low cis and high cis butadiene rubber with Lotader® terpolymer in the composition.

[0058] Therefore, a terpolymer of ethylene, acrylic ester and maleic anhydride combined with a natural rubber and optionally a low cis or a high cis butadiene rubber results in a lower hysteresis while maintaining good mechanical properties. Such cross-linked rubber compositions are particularly usable for manufacturing a tyre rim cushion.