Rubber composition and pneumatic tire having tread fabricated using rubber composition

Abstract

Provided are a rubber composition that shows a balanced improvement in fuel economy, abrasion resistance, and wet grip performance while having good processability, and a pneumatic tire including a tread formed from the rubber composition. The present invention relates to a rubber composition containing: a copolymer synthesized by copolymerization of a conjugated diene monomer and a compound represented by the formula (1) below; and carbon black and/or silica, ##STR00001##
wherein R.sup.11 and R.sup.12 are the same as or different from each other and each represent a hydrogen atom or a C1-C30 hydrocarbon group.

Claims

1. A pneumatic tire, comprising: a tread comprising a rubber composition comprising a copolymer and at least one of carbon black and silica, wherein the copolymer comprises a first monomer unit derived from 1, 3-butadiene and a second monomer unit derived from a compound represented by formula (1), ##STR00009## where R.sup.11 and R.sup.12 are the same or different from each other and each represent a hydrogen atom or a C1-C30 hydrocarbon group, and the copolymer comprises the first monomer unit in a range of 5% to 95% by mass and the second monomer unit in a range of 5% to 95% by mass per 100% by mass of structural units of the copolymer, the copolymer is produced by synthesizing the 1, 3-butadiene and the compound represented by the formula (1) by emulsion polymerization, and the copolymer has a weight average molecular weight in a range of 5,000 to 2,000,000 and a molecular weight distribution in a range of 2.1 to 11.

2. The pneumatic tire according to claim 1, wherein R.sup.11 and R.sup.12 are ethyl groups.

3. The pneumatic tire according to claim 1, wherein the copolymer is produced by further emulsion polymerizing a compound represented by formula (2), ##STR00010## where R.sup.21 represents a hydrogen atom, a C1-C3 aliphatic hydrocarbon group, a C3-C8 alicyclic hydrocarbon group, or a C6-C10 aromatic hydrocarbon group, and R.sup.22 represents a hydrogen atom or a methyl group, and the copolymer comprises 1% to 50% by mass of units derived from the compound represented by the formula (2) per 100% by mass of structural units of the copolymer.

4. The pneumatic tire according to claim 1, wherein the copolymer is produced by the emulsion polymerization in the presence of a chain transfer agent.

5. The pneumatic tire according to claim 1, wherein the copolymer is produced by synthesizing the 1, 3-butadiene and the compound represented by the formula (1) in the presence of a chain transfer agent comprising a compound having a mercapto group and a functional group having an affinity for filler.

6. The pneumatic tire according to claim 1, wherein the copolymer is produced by synthesizing the 1, 3-butadiene and the compound represented by the formula (1) by emulsion polymerization, and the copolymer has a glass transition temperature in a range of 100 C. to 100 C. and a Mooney viscosity ML.sub.1+4 at 130 C. in a range of 30 to 100.

7. The pneumatic tire according to claim 2, wherein the copolymer further comprises a third monomer unit derived from a compound represented by formula (2), ##STR00011## where R.sup.21 represents a hydrogen atom, a C1-C3 aliphatic hydrocarbon group, a C3-C8 alicyclic hydrocarbon group, or a C6-C10 aromatic hydrocarbon group, and R.sup.22 represents a hydrogen atom or a methyl group, and the copolymer comprises the third monomer unit in a range of 1% to 50% by mass per 100% by mass of structural units of the copolymer.

8. A pneumatic tire, comprising: a tread comprising a rubber composition comprising a copolymer and at least one of carbon black and silica, wherein the copolymer comprises a first monomer unit derived from 1, 3-butadiene and a second monomer unit derived from a compound represented by formula (1), ##STR00012## where R.sup.11 and R.sup.12 are the same or different from each other and each represent a hydrogen atom or a C1-C30 hydrocarbon group, and the copolymer is produced by synthesizing the 1, 3-butadiene and the compound represented by the formula (1) by emulsion polymerization, and the copolymer has a weight average molecular weight in a range of 5,000 to 2,000,000 and a molecular weight distribution in a range of 2.1 to 11.

9. The pneumatic tire according to claim 8, wherein R.sup.11 and R.sup.12 are ethyl groups.

10. The pneumatic tire according to claim 8, wherein the copolymer further comprises a third monomer unit derived from a compound represented by formula (2), ##STR00013## where R.sup.21 represents a hydrogen atom, a C1-C3 aliphatic hydrocarbon group, a C3-C8 alicyclic hydrocarbon group, or a C6-C10 aromatic hydrocarbon group, and R.sup.22 represents a hydrogen atom or a methyl group, and the copolymer comprises the third monomer unit in a range of 1% to 50% by mass per 100% by mass of structural units of the copolymer.

11. The pneumatic tire according to claim 8, wherein the copolymer is produced by synthesizing the 1, 3-butadiene and the compound represented by the formula (1) by emulsion polymerization in the presence of a chain transfer agent.

12. A pneumatic tire, comprising: a tread comprising a rubber composition comprising a copolymer and at least one of carbon black and silica, wherein the copolymer comprises a first monomer unit derived from 1, 3-butadiene and a second monomer unit derived from a compound represented by formula (1), ##STR00014## where R.sup.11 and R.sup.12 are ethyl groups.

13. The pneumatic tire according to claim 12, wherein the copolymer further comprises a third monomer unit derived from a compound represented by formula (2), ##STR00015## where R.sup.21 represents a hydrogen atom, a C1-C3 aliphatic hydrocarbon group, a C3-C8 alicyclic hydrocarbon group, or a C6-C10 aromatic hydrocarbon group, and R.sup.22 represents a hydrogen atom or a methyl group, and the copolymer comprises the third monomer unit in a range of 1% to 50% by mass per 100% by mass of structural units of the copolymer.

14. The pneumatic tire according to claim 12, wherein the copolymer is produced by synthesizing the 1, 3-butadiene and the compound represented by the formula (1) by emulsion polymerization in the presence of a chain transfer agent.

15. A pneumatic tire, comprising: a tread comprising a rubber composition comprising a copolymer and at least one of carbon black and silica, wherein the copolymer comprises a first monomer unit derived from 1, 3-butadiene and a second monomer unit derived from a compound represented by formula (1), ##STR00016## where R.sup.11 and R.sup.12 are the same or different from each other and each represent a hydrogen atom or a C1-C30 hydrocarbon group, and the copolymer comprises the first monomer unit in a range of 5% to 95% by mass and the second monomer unit in a range of 5% to 95% by mass per 100% by mass of structural units of the copolymer, and the copolymer has a weight average molecular weight in a range of 5,000 to 2,000,000.

16. A pneumatic tire, comprising: a tread comprising a rubber composition comprising a copolymer and at least one of carbon black and silica, wherein the copolymer comprises a first monomer unit derived from 1, 3-butadiene and a second monomer unit derived from a compound represented by formula (1), ##STR00017## where R.sup.11 and R.sup.12 are the same or different from each other and each represent a hydrogen atom or a C1-C30 hydrocarbon group, and the copolymer comprises the first monomer unit in a range of 5% to 95% by mass and the second monomer unit in a range of 5% to 95% by mass per 100% by mass of structural units of the copolymer, and the copolymer has a molecular weight distribution in a range of 2.1 to 11.

17. The pneumatic tire according to claim 2, wherein the copolymer is produced by synthesizing the 1, 3-butadiene and the compound represented by the formula (1) by emulsion polymerization in the presence of a chain transfer agent.

18. The pneumatic tire according to claim 2, wherein the copolymer is produced by synthesizing the 1, 3-butadiene and the compound represented by the formula (1) in the presence of a chain transfer agent comprising a compound having a mercapto group and a functional group having an affinity for filler.

19. The pneumatic tire according to claim 2, wherein the copolymer is produced by synthesizing the 1, 3-butadiene and the compound represented by the formula (1) by emulsion polymerization, and the copolymer has a glass transition temperature in a range of 100 C. to 100 C. and a Mooney viscosity ML.sub.1+4 at 130 C. in a range of 30 to 100.

20. The pneumatic tire according to claim 3, wherein the copolymer is produced by synthesizing the 1, 3-butadiene and the compound represented by the formula (1) by emulsion polymerization in the presence of a chain transfer agent.

21. The pneumatic tire according to claim 3, wherein the copolymer is produced by synthesizing the 1, 3-butadiene and the compound represented by the formula (1) in the presence of a chain transfer agent comprising a compound having a mercapto group and a functional group having an affinity for filler.

22. A pneumatic tire, comprising: a tread comprising a rubber composition comprising a copolymer, carbon black and silica, wherein the carbon black has a nitrogen adsorption specific surface area of 100 m.sup.2/g or more, the copolymer comprises a first monomer unit derived from 1, 3-butadiene and a second monomer unit derived from a compound represented by formula (1), ##STR00018## where R.sup.11 and R.sup.12 are the same or different from each other and each represent a hydrogen atom or a C1-C30 hydrocarbon group, and the copolymer comprises the first monomer unit in a range of 5% to 95% by mass and the second monomer unit in a range of 5% to 95% by mass per 100% by mass of structural units of the copolymer, and the copolymer has a glass transition temperature in a range of 100 C. to 100 C.

Description

EXAMPLES

(1) The present invention is specifically described with reference to examples but is not limited thereto.

(2) The chemicals used in production examples are listed below.

(3) Ion-exchanged water: In-house product

(4) Potassium rosinate soap: available from Harima Chemicals Group, Inc.

(5) Fatty acid sodium soap: available from Wako Pure Chemical Industries, Ltd.

(6) Potassium chloride: available from Wako Pure Chemical Industries, Ltd.

(7) Sodium naphthalenesulfonate-formaldehyde condensate: available from Kao Corporation

(8) Styrene: Styrene available from Wako Pure Chemical Industries, Ltd.

(9) 1,3-Butadiene: 1,3-Butadiene available from Takachiho Trading Co., Ltd.

(10) t-Dodecyl mercaptan: tert-Dodecyl mercaptan available from Wako Pure Chemical Industries, Ltd. (chain transfer agent)

(11) Si363: 3-[Ethoxybis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silyl]-1-propanethiol available from Degussa (chain transfer agent, a compound represented by the formula below)

(12) ##STR00008##

(13) 2-Ethylhexyl 3-mercaptopropionate: available from Tokyo Chemical Industry Co., Ltd. (chain transfer agent)

(14) 2-Mercaptoethyl octanoate: available from Tokyo Chemical Industry Co., Ltd. (chain transfer agent)

(15) 3-Mercaptopropyltriethoxysilane: available from Tokyo Chemical Industry Co., Ltd. (chain transfer agent, a compound represented by formula (3))

(16) Sodium hydrosulfide: available from Wako Pure Chemical Industries, Ltd.

(17) FeSO.sub.4: Ferric sulfate available from Wako Pure Chemical Industries, Ltd.

(18) EDTA: Sodium ethylenediaminetetraacetate available from Wako Pure Chemical Industries, Ltd.

(19) Rongalite: Sodium formaldehyde sulfoxylate available from Wako Pure Chemical Industries, Ltd.

(20) Polymerization initiator: Paramenthane hydroperoxide available from NOF Corporation

(21) Polymerization terminator: N,N-Diethylhydroxylamine available from Wako Pure Chemical Industries, Ltd.

(22) 2,6-Di-t-butyl-p-cresol: Sumilizer BHT available from Sumitomo Chemical Co., Ltd.

(23) Diethyl itaconate (IDE): available from Tokyo Chemical Industry Co., Ltd.

(24) Dibutyl itaconate (IDB): available from Tokyo Chemical Industry Co., Ltd.

(25) (Preparation of Emulsifier)

(26) An emulsifier was prepared by adding 9,356 g of ion-exchanged water, 1,152 g of potassium rosinate soap, 331 g of fatty acid sodium soap, 51 g of potassium chloride, and 30 g of sodium naphthalenesulfonate-formaldehyde condensate, followed by stirring at 70 C. for 2 hours.

Production Example 1

(27) A 50 L (interior volume) stainless-steel polymerization reactor was cleaned, dried, and purged with dry nitrogen. Then, the reactor was charged with 3,500 g of 1,3-butadiene, 1,500 g of styrene, 5.74 g of t-dodecyl mercaptan, 9,688 g of the emulsifier, 6.3 ml of sodium hydrosulfide (1.8 M), 6.3 ml each of the activators (FeSO.sub.4/EDTA/Rongalite), and 6.3 ml of the polymerization initiator (2.3 M), followed by polymerization at 10 C. for 3 hours with stirring. After the completion of the polymerization, 2.9 g of N,N-diethylhydroxylamine was added to the reaction mixture and they were reacted for 30 minutes. The contents were taken out from the polymerization reactor and combined with 10 g of 2,6-di-t-butyl-p-cresol. After most of the water was evaporated off, the residue was dried under reduced pressure at 55 C. for 12 hours to give a copolymer 1.

Production Example 2

(28) A copolymer 2 was prepared in the same manner as in Production Example 1, except that 1,500 g of diethyl itaconate (IDE) was used instead of 1,500 g of styrene.

Production Example 3

(29) A copolymer 3 was prepared in the same manner as in Production Example 1, except that 1,500 g of dibutyl itaconate (IDB) was used instead of 1,500 g of styrene.

Production Example 4

(30) A copolymer 4 was prepared in the same manner as in Production Example 1, except that 1,500 g of diethyl itaconate (IDE) was used instead of 1,500 g of styrene, and 6.40 g of Si363 was used instead of 5.74 g of t-dodecyl mercaptan.

Production Example 5

(31) A copolymer 5 was prepared in the same manner as in Production Example 1, except that 750 g out of 1,500 g of styrene was replaced with 750 g of diethyl itaconate (IDE).

Production Example 6

(32) A copolymer 6 was prepared in the same manner as in Production Example 1, except that 750 g out of 1,500 g of styrene was replaced with 750 g of diethyl itaconate (IDE), and 5.74 g of t-dodecyl mercaptan was replaced with 6.40 g of Si363.

Production Example 7

(33) A copolymer 7 was prepared in the same manner as in Production Example 1, except that 1,500 g of diethyl itaconate (IDE) was used instead of 1,500 g of styrene, and 6.11 g of 2-ethylhexyl 3-mercaptopropionate was used instead of 5.74 g of t-dodecyl mercaptan.

Production Example 8

(34) A copolymer 8 was prepared in the same manner as in Production Example 1, except that 750 g out of 1,500 g of styrene was replaced with diethyl itaconate (IDE), and 5.74 g of t-dodecyl mercaptan was replaced with 6.11 g of 2-ethylhexyl 3-mercaptopropionate.

Production Example 9

(35) A copolymer 9 was prepared in the same manner as in Production Example 1, except that 1,500 g of diethyl itaconate (IDE) was used instead of 1,500 g of styrene, and 6.11 g of 2-mercaptoethyl octanoate was used instead of 5.74 g of t-dodecyl mercaptan.

Production Example 10

(36) A copolymer 10 was prepared in the same manner as in Production Example 1, except that 750 g out of 1,500 g of styrene was replaced with diethyl itaconate (IDE), and 5.74 g of t-dodecyl mercaptan was replaced with 6.11 g of 2-mercaptoethyl octanoate.

Production Example 11

(37) A copolymer 11 was prepared in the same manner as in Production Example 1, except that 1,500 g of styrene was replaced with diethyl itaconate (IDE), and 5.74 g of t-dodecyl mercaptan was replaced with 6.11 g of 3-mercaptopropyltriethoxysilane.

Production Example 12

(38) A copolymer 12 was prepared in the same manner as in Production Example 1, except that 750 g out of 1,500 g of styrene was replaced with diethyl itaconate (IDE), and 5.74 g of t-dodecyl mercaptan was replaced with 6.11 g of 3-mercaptopropyltriethoxysilane.

(39) Table 1 shows the amount of butadiene (conjugated diene monomer), the amount of diethyl itaconate or dibutyl itaconate (compound represented by formula (1)), the amount of styrene (compound represented by formula (2)), Mw, Mw/Mn, Tg, and Mooney viscosity of the copolymers 1 to 12 prepared in Production Examples 1 to 12. These values were determined as collectively described below.

(40) (Amount of Each of Monomer Units)

(41) A .sup.1H-NMR spectrum was measured using an NMR device available from Bruker at 23 C. The ratio of the peaks from the phenyl protons of the styrene units at 6.5 to 7.2 ppm, the vinyl protons of the butadiene units at 4.9 to 5.4 ppm, and the isobutyl vinyl ether units at 3.9 to 4.2 ppm was determined based on the spectrum. Then, the amounts of the monomer units were determined from the ratio.

(42) (Measurement of Weight Average Molecular Weight (Mw) and Number Average Molecular Weight (Mn))

(43) The weight average molecular weight (Mw) and the number average molecular weight (Mn) of each copolymer were determined relative to polystyrene standards using a gel permeation chromatograph (GPC) (GPC-8000 series available from Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M available from Tosoh Corporation).

(44) (Measurement of Glass Transition Temperature (Tg))

(45) The glass transition temperature (Tg) is defined as the glass transition onset temperature measured using a differential scanning calorimeter (Q200) available from TA Instruments, Japan at a temperature increase rate of 10 C./min in accordance with JIS K 7121.

(46) (Mooney Viscosity (ML.sub.1+4, 130 C.)

(47) After preheating at 130 C. for 1 minute, each rubber was measured for Mooney viscosity (ML.sub.1+4, 130 C.) for 4 minutes using a Mooney viscometer (SMV-200) available from Shimadzu Corporation in accordance with JIS K 6300.

(48) TABLE-US-00001 TABLE 1 Production Production Production Production Production Production Production Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Amount of butadiene 76 76 76 76 76 76 76 (conjugated diene monomer) (% by mass) Amount of diethyl itaconate or 24 24 24 12 12 24 dibutyl itaconate (formula (1)) (% by mass) Amount of styrene (formula (2)) 24 12 12 (% by mass) Weight average molecular weight 510,000 500,000 495,000 495,000 520,000 520,000 490,000 (Mw) Molecular weight distribution 3.6 3.7 4.1 4.1 3.9 4.1 4.1 (Mw/Mn) Tg ( C.) 51 48 55 45 42 38 46 Mooney viscosity 52 46 42 51 52 56 49 (ML.sub.1+4, 130 C.) Production Production Production Production Production Example 8 Example 9 Example 10 Example 11 Example 12 Amount of butadiene 76 76 76 76 76 (conjugated diene monomer) (% by mass) Amount of diethyl itaconate or 12 24 12 24 12 dibutyl itaconate (formula (1)) (% by mass) Amount of styrene (formula (2)) 12 12 12 (% by mass) Weight average molecular weight 520,000 495,000 510,000 500,000 520,000 (Mw) Molecular weight distribution 4 4 3.9 3.8 3.8 (Mw/Mn) Tg ( C.) 41 47 42 45 41 Mooney viscosity 53 49 52 51 55 (ML.sub.1+4, 130 C.)

(49) The chemicals used in examples and comparative example were listed below.

(50) Rubber component: Copolymers 1 to 12 prepared in Production Examples 1 to 12

(51) Carbon black: SHOBLACK N220 (N.sub.2SA: 111 m.sup.2/g, DBP: 115 ml/100 g) available from Cabot Japan K.K.

(52) Silica: ULTRASIL VN3 (N.sub.2SA: 175 m.sup.2/g) available from Degussa

(53) Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide) available from Degussa

(54) Zinc oxide: Zinc oxide #1 available from Mitsui Mining and Smelting Co., Ltd.

(55) Stearic acid: Stearic acid available from NOF Corporation

(56) Antioxidant: NOCRAC 6C (N-1,3-dimethylbutyl-N-phenyl-p-phenylenediamine) available from Ouchi Shinko Chemical Industrial Co., Ltd.

(57) Wax: Sunnoc Wax available from Ouchi Shinko Chemical Industrial Co., Ltd.

(58) Vulcanization accelerator 1: Nocceler CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) available from Ouchi Shinko Chemical Industrial Co., Ltd.

(59) Vulcanization accelerator 2: Nocceler D (N,N-diphenylguanidine) available from Ouchi Shinko Chemical Industrial Co., Ltd.

(60) Sulfur: Sulfur powder available from Tsurumi Chemical Industry Co., Ltd.

Examples and Comparative Example

(61) According to the formulations shown in Table 2, the chemicals other than the sulfur and vulcanization accelerators were kneaded using a Banbury mixer at 150 C. for 5 minutes. To the kneaded mixture were added the sulfur and vulcanization accelerators, and they were kneaded using an open roll mill at 170 C. for 12 minutes to prepare an unvulcanized rubber composition.

(62) The unvulcanized rubber composition was press-vulcanized at 170 C. for 20 minutes to prepare a vulcanized rubber composition.

(63) The unvulcanized rubber compositions and vulcanized rubber compositions thus prepared were evaluated as follows.

(64) Table 2 shows the results.

(65) (Processability)

(66) Each unvulcanized rubber composition was measured for Mooney viscosity at 100 C. in accordance with JIS K 6300. A lower Mooney viscosity indicates better processability.

(67) (Fuel Economy)

(68) The tan of each vulcanized rubber composition was measured using the viscoelasticity spectrometer VES (Iwamoto Seisakusho Co., Ltd.) at a temperature of 30 C., an initial strain of 10%, and a dynamic strain of 2%. A lower tan indicates better fuel economy.

(69) (Wet Grip Performance)

(70) A viscoelastic parameter was determined for specimens prepared from each vulcanized rubber composition, using a viscoelastometer (ARES) available from Rheometric Scientific in a torsional mode. The tan was measured at 0 C., a frequency of 10 Hz, and a strain of 1%. A higher tan indicates better wet grip performance.

(71) (Abrasion Resistance)

(72) Using a Lambourn abrasion tester, the abrasion loss of each vulcanized rubber composition was measured at room temperature, an applied load of 1.0 kgf, and a slip ratio of 30% and expressed as an index using the equation below. A higher index indicates better abrasion resistance.
(Abrasion resistance index)=(Abrasion loss of Comparative Example 1)/(Abrasion loss in each formulation)100

(73) TABLE-US-00002 TABLE 2 Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Formulation (parts by mass) Copolymer 1 100 Copolymer 2 100 Copolymer 3 100 Copolymer 4 100 Copolymer 5 100 Copolymer 6 100 Copolymer 7 Copolymer 8 Copolymer 9 Copolymer 10 Copolymer 11 Copolymer 12 Carbon black 5 5 5 5 5 5 Silica 75 75 75 75 75 75 Silane coupling agent 6 6 6 6 6 6 Zinc oxide 2 2 2 2 2 2 Stearic acid 2 2 2 2 2 2 Antioxidant 2 2 2 2 2 2 Wax 2 2 2 2 2 2 Vulcanization 1.5 1.5 1.5 1.5 1.5 1.5 accelerator 1 Vulcanization 2 2 2 2 2 2 accelerator 2 Sulfur 1.5 1.5 1.5 1.5 1.5 1.5 Evaluation Processability 61 37 45 45 48 52 (Mooney viscosity (ML.sub.1+4 at 100 C.)) Fuel economy 0.228 0.208 0.22 0.156 0.215 0.199 (30 C., tan ) Wet grip performance 0.454 0.619 0.561 0.602 0.722 0.712 (0 C., tan ) Abrasion resistance 100 130 110 152 150 171 (Lambourn test) Example Example 6 Example 7 Example 8 Example 9 10 Example 11 Formulation (parts by mass) Copolymer 1 Copolymer 2 Copolymer 3 Copolymer 4 Copolymer 5 Copolymer 6 Copolymer 7 100 Copolymer 8 100 Copolymer 9 100 Copolymer 10 100 Copolymer 11 100 Copolymer 12 100 Carbon black 5 5 5 5 5 5 Silica 75 75 75 75 75 75 Silane coupling agent 6 6 6 6 6 6 Zinc oxide 2 2 2 2 2 2 Stearic acid 2 2 2 2 2 2 Antioxidant 2 2 2 2 2 2 Wax 2 2 2 2 2 2 Vulcanization 1.5 1.5 1.5 1.5 1.5 1.5 accelerator 1 Vulcanization 2 2 2 2 2 2 accelerator 2 Sulfur 1.5 1.5 1.5 1.5 1.5 1.5 Evaluation Processability 51 52 46 49 50 56 (Mooney viscosity (ML.sub.1+4 at 100 C.)) Fuel economy 0.2 0.211 0.201 0.208 0.198 0.199 (30 C., tan ) Wet grip performance 0.571 0.709 0.571 0.702 0.598 0.711 (0 C., tan ) Abrasion resistance 135 152 132 155 138 160 (Lambourn test)

(74) Table 2 demonstrates that, in the examples in which each of the copolymers 2 to 12 in the present invention was contained, a balanced improvement in fuel economy, abrasion resistance, and wet grip performance was achieved while providing good processability.