RUBBER COMPOSITION, AND TIRE USING THE SAME

Abstract

Disclosed is a rubber composition and a tire using the same. The rubber composition comprises a rubber matrix and a compounding component. In parts by weight, every 100 parts by weight of said rubber matrix comprises 5-95 parts by weight of a branched polyethylene, 5-90 parts by weight of a highly unsaturated diene elastomer and 0-30 parts by weight of a low unsaturated diene elastomer; and said compounding component comprises a vulcanization system and a filler. The rubber composition has good aging resistance and mechanical properties, and can be applied for products such as tires, rubber hoses, rubber tapes and so on, in which the traditional, easily aging diene rubber was commonly used.

Claims

1. A rubber composition, comprising a rubber matrix and a compounding component, wherein, every 100 parts by weight of said rubber matrix comprises 5-95 parts by weight of a branched polyethylene, 5-90 parts by weight of a highly unsaturated diene elastomer and 0-30 parts by weight of a low unsaturated diene elastomer; and said compounding component comprises a vulcanization system and a filler.

2. The rubber composition according to claim 1, wherein, said branched polyethylene is an ethylene homopolymer having a branching degree of not lower than 50 branches/1,000 carbons.

3. The rubber composition according to claim 2, wherein, said branched polyethylene is an ethylene homopolymer having a branching degree of 70-120 branches/1,000 carbons.

4. The rubber composition according to claim 2, wherein, said branched polyethylene is an ethylene homopolymer having a branching degree of 82-112 branches/1,000 carbons.

5. The rubber composition according to claim 1, wherein, the polymeric monomers of said highly unsaturated diene elastomer includes diene polymeric monomers with a molar content not lower than 15%.

6. The rubber composition according to claim 5, wherein, the polymeric monomers of said highly unsaturated diene elastomer includes diene polymeric monomers with a molar content not lower than 50%.

7. The rubber composition according to claim 1, wherein, said highly unsaturated diene elastomer is selected from at least one of natural rubber (NR), butadiene/styrene copolymer (SBR), polybutadiene (BR), synthetic polyisoprene (IR), isoprene/butadiene copolymer (BIR), isoprene/styrene copolymer (SIR) or isoprene/butadiene/styrene copolymer (SBIR).

8. The rubber composition according to claim 1, wherein, the polymeric monomers of said low unsaturated diene elastomer includes diene polymeric monomers with a molar content lower than 15%.

9. The rubber composition according to claim 1, wherein, said low unsaturated diene elastomer is selected from at least one of ethylene-propylene-diene terpolymer and halogenated butyl rubber.

10. The rubber composition according to claim 9, wherein, said low unsaturated diene elastomer is composed of one or more ethylene-propylene-diene terpolymers, in which the content of propylene is 15%-95%; and in every 100 parts of said rubber matrix, the content of all the ethylene-propylene-diene terpolymers is 5-30 parts.

11. The rubber composition according to claim 9, wherein, said low unsaturated diene elastomer is an ethylene-propylene-diene terpolymer, in which the content of ethylene is 2 wt %-40 wt %, the content of propylene is 60 wt %-95 wt %, and the content of diene is 0.5 wt %-12 wt %.

12. The rubber composition according to claim 9, wherein, said low unsaturated diene elastomer is an ethylene-propylene-diene terpolymer, in which the diene is selected from at least one of 5-ethylidene-2-norbornene and vinyl norbornene.

13. The rubber composition according to claim 1, wherein, said vulcanization system is a peroxide vulcanization system or a peroxide-sulfur mixed vulcanization system.

14. The rubber composition according to claim 1, wherein, said filler is selected from silica-based fillers, carbon black, or a blend of silica-based fillers and carbon black.

15. The rubber composition according to claim 1, wherein, based on 100 parts by weight of said rubber matrix, said compounding component comprises 2-80 parts of a plasticizer, 0-3 parts of a stearic acid, 0-10 parts of a metal oxide, 0-20 parts of a surface modifier, 0-8 parts of a stabilizer, 0-15 parts of a tackifier and 0-20 parts of an adhesive.

16. A tire, wherein, the rubber composition used for the tread of said tire comprises said rubber composition according to claim 1.

17. A tire, wherein, the rubber composition used for the sidewall of said tire comprises said rubber composition according to claim 1.

Description

DETAILED DESCRIPTION

[0052] The following provides descriptions of the present invention, but is not intended to limit the scope of the present invention. Some non-essential improvements and adjustments made to the present invention by a person of ordinary skill in the art according to the summary still fall within the protection scope of the present invention.

[0053] The branched polyethylene used in the embodiments can be obtained by catalyzing homopolymerization of ethylene by a (α-diimine) nickel catalyst under the action of a cocatalyst. The structure and synthesis method of the (α-diimine) nickel catalyst used and the method for preparing branched polyethylene with the (α-diimine) nickel catalyst are disclosed prior art. The documents used may include, but not limited to, CN102827312A, CN101812145A, CN101531725A, CN104926962A, U.S. Pat. No. 6,103,658, and U.S. Pat. No. 6,660,677.

[0054] The branched polyethylene raw materials used in the embodiments have the following characteristics: the branching degree is preferably 50-130 branches/1,000 carbons, a weight average molecular weight is preferably 6.6×10.sup.4-53.4×10.sup.4 g/mol, and a Mooney viscosity ML(1+4)125° C. is preferably 6-105. The branching degree is more preferably 82-112 branches/1,000 carbons, the weight average molecular weight is preferably 20×10.sup.4-40×10.sup.4 g/mol, and the Mooney viscosity ML(1+4)125° C. is preferably 20-80. The branching degree is measured by hydrogen NMR spectroscopy, and the mole percentages of various branches are measured by carbon NMR spectroscopy.

[0055] The branched polyethylene raw materials used in the embodiments may be further selected from the following table:

TABLE-US-00001 Hexyl Weight and average Molecular Mooney Branched longer molecular weight viscosity polyethylene Branching Methyl Ethyl Propyl Butyl Amyl branch weight/ten distri- ML(1 + 4) number degree content/% content/% content/% content/% content/% content% thousand bution 125° C. PER-1 130 46.8 18.3 8.3 6.7 5.2 14.7 6.6 2.2 6 PER-2 120 49.2 17.9 8.2 6.1 5.1 13.5 8.2 2.1 12 PER-3 112 52.4 16.2 7.6 5.6 4.9 13.3 22.5 1.9 32 PER-4 105 54.0 13.7 6.4 5.3 5.1 15.5 26.8 2.1 42 PER-5 102 56.2 12.9 6.2 5.2 4.9 14.6 27.9 2.1 52 PER-6 99 59.6 11.6 5.8 4.9 5.1 13.0 28.3 1.8 63 PER-7 97 60.5 10.8 5.7 4.7 4.9 13.3 34.8 2.0 65 PER-8 90 62.1 9.4 5.4 4.6 4.5 14.0 32.1 2.1 77 PER-9 82 64.2 8.7 5.3 4.2 3.9 13.7 35.6 1.7 80 PER-10 72 67.1 6.2 3.7 4.1 3.3 15.6 15.8 1.9 20 PER-11 70 66.5 7.2 4.6 3.2 3.2 15.3 43.6 2.1 93 PER-12 60 68.1 7.1 4.2 2.7 2.8 15.1 51.8 2.2 102 PER-13 50 69.2 7.1 3.9 2.5 2.6 14.7 53.4 2.3 105

[0056] In a specific embodiment, the highly unsaturated diene elastomer may be selected from polybutadiene (BR), synthetic polyisoprene (IR), natural rubber (NR), butadiene/styrene copolymer (SBR), isoprene/butadiene copolymer (BIR), isoprene/styrene copolymer (SIR), isoprene/butadiene/styrene copolymer (SBIR) or mixtures thereof.

[0057] In a preferred embodiment, the highly unsaturated diene elastomer mainly includes SBR. The SBR may be emulsion polymerized styrene-butadiene rubber (ESBR) or solution polymerized styrene-butadiene rubber (SSBR), which has an appropriate styrene content, for example, 20 wt %-35 wt %, or a high styrene content, for example, 35 wt %-45 wt %. The high styrene content is beneficial to improving wet skid resistance of the rubber composition. In the butadiene part, a 1,2 structure content is 10%-65%, a trans-1,4 structure content is 15%-75%, and Tg is between −65° C. and −10° C.

[0058] In another embodiment, the highly unsaturated diene elastomer is a composition of different diene elastomers, for example, SBR/BR, or SBR/NR, or SBR/IR, or SBR/BR/NR, or SBR/BR/IR, or NR/BR, or IR/BR. The polybutadiene is preferably a species with a cis-1,4 structure content (mol %) of greater than 80%. The synthetic polyisoprene elastomer is preferably a species with a cis-1,4 structure content (mol %) of greater than 90%, and more preferably a species with a cis-1,4 structure content (mol %) of greater than 98%.

[0059] In another aspect, the highly unsaturated diene elastomer composition in the embodiment preferably includes both an elastomer having a high glass transition temperature (Tg is not lower than −70° C.) and an elastomer having a low glass transition temperature (Tg is −110° C.-−80° C., preferably −100° C.-−90° C.). The elastomer having a high glass transition temperature may be selected from SSBR, ESBR, NR, high-cis-1,4-content IR, BIR, SIR, SBIR, and a mixture of these elastomers. The elastomer having a low glass transition temperature is preferably BR with a high cis-1,4 structure content.

[0060] In another embodiment, the highly unsaturated diene elastomer composition includes both SSBR or ESBR having a high glass transition temperature and high cis BR having a low glass transition temperature.

[0061] The styrene-butadiene rubber used in the embodiments of the present invention may be selected from the following table:

TABLE-US-00002 Designation of Bound Mooney Type of styrene-butadiene styrene viscosity anti-aging rubber content/% ML(1 + 4)100° C. agent SBR1502 23.5 52 Non-polluting type SBR1516 40 50 Non-polluting type

[0062] The designation of the natural rubber used in the embodiments of the present invention is 3L, Vietnam.

[0063] The polybutadiene rubber used in the embodiments of the present invention is BR9000.

[0064] In a specific embodiment, the low unsaturated diene elastomer is preferably an ethylene-propylene-diene terpolymer. The diene is ENB or VNB. The propylene content is 20 wt %-60 wt %, or 60 wt %-95%.

[0065] The ethylene-propylene-diene terpolymer used in the embodiments may be specifically selected from the following table:

[0066] Low-propylene-content copolymers:

TABLE-US-00003 EPDM Ethylene Propylene ENB Mooney number content/% content/% content/% viscosity EPDM-1 70 25.5 4.5 ML(1 + 4)125° C.: 55 EPDM-2 50 42 8 ML(1 + 4)125° C.: 30 EPDM-3 50 41 9 ML(1 + 4)125° C.: 65 EPDM-4 55 33.5 11.5 ML(1 + 8)100° C.: 55

[0067] High-propylene-content copolymers:

TABLE-US-00004 PEDM Ethylene Propylene ENB MFR(230° C., number content/% content/% content/% 2.16 kg) PEDM-1 11 84.7 4.3 4.2 PEDM-2 4.5 91.4 4.1 2.6

[0068] In another embodiment, the low unsaturated diene elastomer may further includes halogenated butyl rubber, which may be specifically selected from the following table:

TABLE-US-00005 Halogenated butyl Mass percentage Mooney viscosity rubber number of bromine/% ML(1 + 8)125° C. BIIR-1 2 32 BIIR-2 2.1 37 BIIR-3 2.1 46

[0069] In a specific embodiment, the reinforcing filler is carbon black and/or silica. The carbon black may be preferably selected from SAF, ISAF or HAF type carbon black, more specifically, such as N115, N134, N220, N234, N326, N330, N339, N347 and N375, or higher series of carbon black, such as N550, N660 and N772. The carbon black may also be added in the form of a rubber master batch. The silica is preferably a highly dispersible species, for example, Zeosi11165MP or Zeosi11115MP from Rhodia, Ultrasi17000 or Ultrasi17005 from Degussa, and the like.

[0070] In a specific embodiment, when the reinforcing filler contains silica, it is preferable to add a silane coupling agent to assist its reinforcing effect. The silane coupling agent may be selected from sulfur-containing coupling agents, vinyl coupling agents, mercapto coupling agents, amino coupling agents, nitro coupling agents, chlorine-containing coupling agents or epoxy propoxy coupling agents commonly used by those skilled in the art, and more specifically, may be selected from vinyltriethoxysilane (A-151), vinyltrimethoxysilane (A-171), vinyl tris(2-methoxyethoxy)silane (A-172), γ-glycidoxypropyldimethoxysilane (A-187), γ-mercaptopropyl dimethoxysilane (A-189), bis(3-ethoxysilylpropyl)tetrasulfide (Si69), bi s(3 -ethoxysilylpropyl)disulfde(TESPD), γ-aminopropyltriethoxysilane (KH-550) and the like. The sulfur-containing and mercapto-containing coupling agents are more suitable for a sulfur vulcanization system, and the vinyl coupling agents are more suitable for a peroxide vulcanization system.

[0071] In a specific embodiment, the vulcanization system may be selected from a peroxide vulcanization system, a sulfur vulcanization system or a peroxide-sulfur mixed vulcanization system. Optional peroxide crosslinking agents, co-crosslinking agents, sulfur donors and curing accelerators are all species known to those skilled in the art.

[0072] In another embodiment, the compounding component of the rubber composition may further include a plasticizer, zinc oxide, a processing aid, a stabilizer (anti-aging agent) and a tackifier, all of which are known to those skilled in the art.

[0073] In a specific embodiment process, the rubber composition of the present invention may be mixed and cured by any conventional means known to those skilled in the art.

[0074] The rubber composition of the present invention may usually be mixed in one or more suitable mixing devices (such as a Banbury mixer, an open mill and a kneader). Firstly, all the ingredients except the vulcanization system are mixed. This mixing usually takes 3-5 minutes, but a longer or shorter mixing time may also be used. The mixing temperature may range from room temperature or below to a temperature of 150° C. or above. If the mixing temperature used is higher than the activation temperature of the vulcanization system, the rubber should be cooled to below the activation temperature after the mixing is completed, and then the vulcanization system is added through mixing.

[0075] The mixed composition may be formed into a cured tread or sidewall by a suitable extrusion process, and molded together with other tire components in a tire molding machine by a typical method to form an uncured tire. The uncured tire is heated and pressurized in a curing press to obtain the tire.

[0076] Rubber performance test methods involved in the embodiments:

[0077] 1. Hardness test: The test is performed with a hardness tester in accordance with the national standard GB/T531.1-2008, and the test temperature is room temperature.

[0078] 2. Tensile strength and elongation at break performance test: The test is performed with an electronic tensile testing machine in accordance with the national standard GB/T528-2009, the tensile speed is 500 mm/min, the test temperature is 23±2° C., and the sample is a type 2 dumbbell sample.

[0079] 3. Mooney viscosity test: The test is performed with a Mooney viscometer in accordance with the national standard GB/T1232.1-2000.

[0080] 4. Hot air accelerated aging test: The test is performed in a thermal aging test box in accordance with the national standard GB/T3512-2001.

[0081] 5. Compression set test: The test is performed with a compression set device in accordance with the national standard GBAT7759-1996, a type B sample is used, the amount of compression is 25%, and the test temperature is 70° C.

[0082] 6. Ozone aging resistance test: In accordance with the national standard GBAT7762-2003, an ozone cracking resistance test is carried out in the ozone aging chamber, under a certain static tensile strain condition, with an exposure to the air with a certain ozone concentration, and in an environment with a specified temperature (40° C.) and no direct influence of light.

[0083] 7. Curing curve test: The test is performed in a rotorless curemeter in accordance with the national standard GB/T16584-1996.

[0084] 8. Dynamic mechanical property test: DMA-242 dynamic mechanical analyzer produced by NETZSCH (German) is used to analyze the dynamic mechanical properties of the cured rubber. The test conditions are as follows: a double cantilever beam mode is used, the frequency is 10Hz, the tensile displacement is 7%, the test temperature ranges from −100° C.-100° C., and the heating rate is 3K/min.

[0085] 9. Tear strength test: The test is performed with an electronic tensile testing machine in accordance with the national standard GB/T529-2008, the tensile speed is 500 mm/min, the test temperature is 23±2° C., and the sample is a right-angled sample.

[0086] The present invention will be further described below with the embodiments:

Embodiments 1-6

COMPARATIVE EXAMPLE 1

[0087] The present invention provides a rubber composition with good physical and mechanical properties and good aging resistance, which is suitable for preparing cycle tire tread rubber. Embodiments 1-5 are taken as examples for specific formulations.

[0088] The basic formulations of Embodiments 1-5 and Comparative Example 1 are shown in Table 1: (in which the parts by weight of each ingredient relative to every 100 parts by weight of the rubber matrix are listed)

TABLE-US-00006 TABLE 1 Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Comparative Ingredient 1 2 3 4 5 6 Example 1 Styrene- 70 70 40 30 30 70 butadiene rubber 1502 EPDM-2 25 30 Branched 5 30 30 50 70 95 polyethylene Branched PER-9 PER-8 PER-8 PER-8 PER-8 PER-6 polyethylene number Natural rubber 30 20 5 Zinc oxide 5 5 5 5 5 5 5 Stearic acid 2 2 2 2 2 1 2 Silane coupling 2 agent A-172 Calcium carbonate 40 35 Titanate coupling 1 agent Calcined clay 50 50 50 50 White carbon black 20 Carbon black N330 60 60 60 35 50 60 Paraffin oil 20 20 20 10 10 10 20 Sunpar2280 1102 resin 3 3 3 3 3 3 BIPB 1 1 1 1 3 3 1 Sulfur 2 2 2 2 1 0.5 2 TAIC 0.3 0.3 0.3 0.3 0.6 1 0.3 Accelerator 1/0.5 1/0.5 1/0.5 1/0.5 1/0.5 0.75/0 1/0.5 CZ/TMTD ZDMA 2 2 2

[0089] The formulations of Embodiments 1-6 and Comparative Example 1 were processed according to the following method: 50% of reinforcing filler (and coupling agent), 50% of zinc oxide and stearic acid, all of BIPB and TAIC, and 50% of sulfur and accelerator were firstly mixed with EPDM and branched polyethylene to obtain a master batch, the rest rubber matrix ingredients (in which natural rubber was plasticized previously) were mixed with the aforementioned master batch for 1 minute, then the remaining ingredients were added in a conventional sequence, and the mixture was mixed for 2 minutes and discharged. After the rubber mixture was plasticated on an open mill to obtain a sheet with a roll temperature of 60° C., the roll spacing was enlarged to 2 mm, and the sheet was discharged and placed for 20 hours. After curing and placing for 16 hours, the product was subjected to various tests.

[0090] Test results of Embodiments 1-6 and Comparative Example 1 are shown in Table 2:

TABLE-US-00007 TABLE 2 Performance Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Comparative test 1 2 3 4 5 6 Example 1 Hardness 63 64 63 60 62 62 63 (Shore A) Tensile 17.5 18.2 19.2 18.7 17.2 22.5 17.3 strength/MPa Elongation at 503 475 563 521 488 588 509 break/% Tear 37.8 41.6 43.8 40.5 42.6 47.1 36.6 strength/(kN/m) Tensile stress 6.5 6.8 5.4 5.9 6.3 8.3 6.4 at 300% elongation/MPa Ozone resistance (40° No No No No No No No C. × 0.5 μL/L × 20% cracking cracking cracking cracking cracking cracking cracking elongation × 300 h, static)

[0091] Analysis of test results: By comparing Embodiment 1 with Comparative Example 1, it can be found that by replacing part of ethylene-propylene rubber with a small amount of high-molecular-weight branched polyethylene, the overall physical and mechanical properties can be improved without affecting the original effect of improving aging resistance. By comparing Embodiment 2 with Comparative Example 1, it can be found that when all the ethylene-propylene rubber is replaced by the branched polyethylene, the tear strength can be significantly improved, which can also be understood as weakening the influence of adding ethylene-propylene rubber on the original tear strength of the styrene-butadiene rubber. This effect means that more branched polyethylene can be used in the rubber to enhance the aging resistance of the rubber without significantly affecting the physical and mechanical properties of the rubber, which can also be confirmed from the performance in Embodiment 5. The formulations of Embodiments 1-6 can be used to prepare cycle tire tread rubber with good aging resistance.

Embodiments 7-13

COMPARATIVE EXAMPLE 2

[0092] The present invention provides a novel rubber composition for automobile tire tread rubber, which has ideal physical and mechanical properties and matches the required wet skid resistance and low rolling resistance, taking Embodiments 7-13 as examples.

[0093] The basic formulations of Embodiments 7-13 and Comparative Example 2 are shown in Table 3: (in which the parts by weight of each ingredient relative to every 100 parts by weight of the rubber matrix are listed)

TABLE-US-00008 TABLE 3 Comparative Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Ingredient Example 2 7 8 9 10 11 12 13 Styrene- 50 50 50 50 butadiene rubber 1502 Styrene- 20 20 20 20 50 40 40 30 butadiene rubber 1516 EPDM-3 30 10 PEDM-1 10 5 10 10 Branched 20 30 20 25 30 45 20/50 polyethylene Branched PER-7 PER-7 PER-7 PER-7 PER-7 PER-7 PER-3/PER-7 polyethylene number Natural rubber 20 10 Cis-polybutadiene BR9000 20 Zinc oxide 5 5 5 5 5 5 5 5 Stearic acid 2 2 2 2 2 2 2 2 Anti-aging agent RD 2 2 2 2 2 2 2 2 Silane coupling 3 3 3 3 1 1 1 3 agent A-172 Silane coupling 2 2 2 2 2 2 2 2 agent Si69 White carbon black 50 50 50 50 30 30 30 50 Zeosilll65MP Carbon black N220 20 20 20 20 40 40 40 20 Naphthenic oil 18 18 18 18 18 18 18 18 DCP 1.2 1.2 1.2 1.2 1.4 1.5 1.8 1.8 Sulfur 1.2 1.2 1.2 1.2 1 0.8 0.8 0.7 TAIC 0.6 0.6 0.6 0.6 0.7 0.7 0.8 0.8 Accelerator CZ 1.5 1.5 1.5 1.5 1.2 1 1 1

[0094] The formulations of Embodiments 7-13 and Comparative Example 2 were processed according to the following method: 50% of reinforcing filler and coupling agent, 50% of zinc oxide and stearic acid, all of BIPB and TAIC, and 30% of sulfur and accelerator were firstly mixed with branched polyethylene and EPDM or PEDM to obtain a master batch, the rest rubber matrix ingredients (in which natural rubber was plasticized previously) were mixed with the aforementioned master batch for 1 minute, then the remaining ingredients were added in a conventional sequence, and the mixture was mixed for 2 minutes and discharged. After the rubber mixture was plasticated on an open mill to obtain a sheet with a roll temperature of 60° C., the roll spacing was enlarged to 2 mm, and the sheet was discharged and placed for 20 hours. After curing and placing for 16 hours, the product was subjected to various tests.

[0095] Test results of Embodiments 7-13 and Comparative Example 2 are shown in Table 4:

TABLE-US-00009 TABLE 4 Performance Comparative Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment test Example 2 7 8 9 10 11 12 13 Hardness 63 63 63 62 62 62 63 64 (Shore A) Tensile 16.7 19.2 21.1 19.1 20.5 22.5 20.3 22.8 strength/Mpa Elongation at 478 486 456 502 483 518 471 510 break % Tear 39.2 46.6 47.3 48.4 43.5 50.6 48.1 53.8 strength/(kN/m) Tensile stress 11.7 12.9 13.8 12.5 13.1 14.3 12.1 14.2 at 300% elongation/Mpa 0° C. Tanδ 0.42 0.43 0.42 0.46 0.48 0.44 0.43 0.39 60° C. Tanδ 0.15 0.14 0.13 0.13 0.13 0.12 0.11 0.1

[0096] Analysis of test data: Embodiments 7-13 show that the introduction of styrene-butadiene rubber with high styrene content effectively improves the wet skid resistance of the rubber, and the presence of the branched polyethylene, EPDM or PEDM can effectively reduce the rolling resistance of the rubber. On the other hand, the comparison of Embodiments 8 and 9 shows that the introduction of an appropriate amount of PEDM with high propylene content can effectively improve the wet skid resistance, and can also improve the co-curability between the branched polyethylene and the highly unsaturated diene elastomer, and the overall product has a high elongation at break. The comparison of Embodiment 8 and Comparative Example 2 shows that when the EPDM is replaced with the branched polyethylene, the overall product can have better physical and mechanical properties and significantly higher tear strength, and can better satisfy the use requirements of tread rubber.

Embodiments 14-16

COMPARATIVE EXAMPLE 3

[0097] The basic formulations of Embodiments 14-16 and Comparative Example 3 are shown in Table 5: (in which the parts by weight of each ingredient relative to every 100 parts by weight of the rubber matrix are listed)

TABLE-US-00010 TABLE 5 Embodi- Embodi- Embodi- Compar- ment ment ment ative Ingredient 14 15 16 Example 3 Natural rubber 50 50 40 50 EPDM-4 10 30 Branched 30 20 20 polyethylene Branched PER-6 PER-6 PER-7 polyethylene number Halogenated butyl 20 rubber BIIR-2 Cis-polybutadiene 20 20 20 20 Zinc oxide 3 3 3 3 Stearic acid 1 1 1 2 Anti-aging agent MB 1 1 1 1 Carbon black N330 50 50 50 50 Paraffin oil 10 10 10 Naphthenic oil 10 10 10 20 Escorez 1102 resin 5 DCP 0.8 0.8 0.6 Sulfur 0.5 0.5 0.5 1.75 TAIC 0.3 0.3 0.3 HVA-2 1 Accelerator CZ 0.75 0.75 0.75 1

[0098] The formulations of Embodiments 14-16 and Comparative Example 3 were processed according to the following method: 50% of carbon black, 50% of zinc oxide and stearic acid, all of DCP, TAIC and HVA-2, and 30% of sulfur and accelerator were firstly mixed with branched polyethylene, EPDM and BHR to obtain a master batch, the rest rubber matrix ingredients (in which natural rubber was plasticized previously) were mixed with the aforementioned master batch for 1 minute, then the remaining ingredients were added in a conventional sequence, and the mixture was mixed for 2 minutes and discharged. After the rubber mixture was plasticated on an open mill to obtain a sheet with a roll temperature of 60° C., the roll spacing was enlarged to 2mm, and the sheet was discharged and placed for 20 hours. After curing and placing for 16 hours, the product was subjected to various tests.

[0099] Test results of Embodiments 14-16 and Comparative Example 3 are shown in Table 6:

TABLE-US-00011 TABLE 6 Embodi- Embodi- Embodi- Compar- Test ment ment ment ative item 14 15 16 Example 3 Hardness (Shore A) 55 56 54 58 Tensile strength/Mpa 19.1 18.2 16.3 15.2 Elongation at break/% 502 532 541 519 Tear strength 52.2 48.2 43.5 41.1 Tensile stress at 8.7 7.3 7.1 7.5 300% elongation/MPa Ozone resistance (40° No No No No C. × 0.5 μL/L × 20% cracking cracking cracking cracking elongation × 300 h, static) Compression set 22 19 24 31 (70° C. × 22 h) After hot air aging (100° C. × 70 h) Hardness (Shore A) 53 53 52 62 Tensile strength 81 75 72 62 retention/% Elongation at break 88 89 80 47 retention/%

[0100] In Embodiments 14-16, the introduction of branched polyethylene with narrow molecular weight distribution and high molecular weight can impart better aging resistance, physical and mechanical properties, and compression set resistance to the sidewall rubber. The sidewall mentioned above may be the sidewall of a cycle tire or the sidewall of an automobile tire.

[0101] Although the preferred embodiments of the present invention are described in this specification, these embodiments are provided only as examples. It should be understood that variants of the embodiments of the present invention described in this specification may also be used for implementing the present invention. A person of ordinary skill in the art should understand that various variants, changes and replacements may be implemented without departing from the scope of the present invention. It should be understood that the protection scope of each aspect of the present invention is determined by the claims, and a method and a structure in the claims and an equivalent method and structure thereof both fall within the scope of the claims.