WO2020110940A1 - Rubber composition for tire - Google Patents
Rubber composition for tire Download PDFInfo
- Publication number
- WO2020110940A1 WO2020110940A1 PCT/JP2019/045802 JP2019045802W WO2020110940A1 WO 2020110940 A1 WO2020110940 A1 WO 2020110940A1 JP 2019045802 W JP2019045802 W JP 2019045802W WO 2020110940 A1 WO2020110940 A1 WO 2020110940A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- mass
- rubber
- parts
- tire
- rubber composition
- Prior art date
Links
- 229920001971 elastomer Polymers 0.000 title claims abstract description 92
- 239000005060 rubber Substances 0.000 title claims abstract description 92
- 239000000203 mixture Substances 0.000 title claims abstract description 70
- KAKZBPTYRLMSJV-UHFFFAOYSA-N butadiene group Chemical class C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 claims abstract description 48
- 239000005062 Polybutadiene Substances 0.000 claims abstract description 46
- 229920002857 polybutadiene Polymers 0.000 claims abstract description 45
- 239000006229 carbon black Substances 0.000 claims abstract description 29
- 244000043261 Hevea brasiliensis Species 0.000 claims abstract description 14
- 229920003052 natural elastomer Polymers 0.000 claims abstract description 14
- 229920001194 natural rubber Polymers 0.000 claims abstract description 14
- 238000001179 sorption measurement Methods 0.000 claims abstract description 14
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 16
- 239000003795 chemical substances by application Substances 0.000 claims description 13
- 150000001412 amines Chemical class 0.000 claims description 10
- 238000009826 distribution Methods 0.000 claims description 10
- 125000000524 functional group Chemical group 0.000 claims description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims description 8
- 230000003712 anti-aging effect Effects 0.000 claims description 7
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 7
- 125000003545 alkoxy group Chemical group 0.000 claims description 4
- 125000003368 amide group Chemical group 0.000 claims description 4
- 125000003277 amino group Chemical group 0.000 claims description 4
- 125000003700 epoxy group Chemical group 0.000 claims description 4
- 125000005647 linker group Chemical group 0.000 claims description 4
- 238000005096 rolling process Methods 0.000 abstract description 15
- 239000004615 ingredient Substances 0.000 abstract 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 31
- 239000000446 fuel Substances 0.000 description 16
- 238000013329 compounding Methods 0.000 description 15
- 239000000377 silicon dioxide Substances 0.000 description 15
- 238000006116 polymerization reaction Methods 0.000 description 14
- 238000012360 testing method Methods 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 13
- 230000009477 glass transition Effects 0.000 description 12
- 230000020169 heat generation Effects 0.000 description 11
- MZRVEZGGRBJDDB-UHFFFAOYSA-N N-Butyllithium Chemical compound [Li]CCCC MZRVEZGGRBJDDB-UHFFFAOYSA-N 0.000 description 10
- 238000002156 mixing Methods 0.000 description 10
- 239000000945 filler Substances 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 229920003048 styrene butadiene rubber Polymers 0.000 description 8
- 239000003963 antioxidant agent Substances 0.000 description 7
- 230000007423 decrease Effects 0.000 description 7
- 229920003244 diene elastomer Polymers 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 229920000459 Nitrile rubber Polymers 0.000 description 6
- 230000003078 antioxidant effect Effects 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 description 5
- 230000000704 physical effect Effects 0.000 description 5
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 5
- 238000004073 vulcanization Methods 0.000 description 5
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 4
- 238000002788 crimping Methods 0.000 description 4
- 238000005227 gel permeation chromatography Methods 0.000 description 4
- 238000004898 kneading Methods 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 4
- 229920002554 vinyl polymer Polymers 0.000 description 4
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 238000005452 bending Methods 0.000 description 3
- 239000011256 inorganic filler Substances 0.000 description 3
- 229910003475 inorganic filler Inorganic materials 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 239000004594 Masterbatch (MB) Substances 0.000 description 2
- 239000002174 Styrene-butadiene Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 2
- 239000011787 zinc oxide Substances 0.000 description 2
- DLNKOYKMWOXYQA-CBAPKCEASA-N (-)-norephedrine Chemical compound C[C@H](N)[C@H](O)C1=CC=CC=C1 DLNKOYKMWOXYQA-CBAPKCEASA-N 0.000 description 1
- ZNRLMGFXSPUZNR-UHFFFAOYSA-N 2,2,4-trimethyl-1h-quinoline Chemical compound C1=CC=C2C(C)=CC(C)(C)NC2=C1 ZNRLMGFXSPUZNR-UHFFFAOYSA-N 0.000 description 1
- GAODDBNJCKQQDY-UHFFFAOYSA-N 2-methyl-4,6-bis(octylsulfanylmethyl)phenol Chemical compound CCCCCCCCSCC1=CC(C)=C(O)C(CSCCCCCCCC)=C1 GAODDBNJCKQQDY-UHFFFAOYSA-N 0.000 description 1
- ZZMVLMVFYMGSMY-UHFFFAOYSA-N 4-n-(4-methylpentan-2-yl)-1-n-phenylbenzene-1,4-diamine Chemical compound C1=CC(NC(C)CC(C)C)=CC=C1NC1=CC=CC=C1 ZZMVLMVFYMGSMY-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- KWYHDKDOAIKMQN-UHFFFAOYSA-N N,N,N',N'-tetramethylethylenediamine Chemical compound CN(C)CCN(C)C KWYHDKDOAIKMQN-UHFFFAOYSA-N 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical group CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 235000021355 Stearic acid Nutrition 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 125000003172 aldehyde group Chemical group 0.000 description 1
- 125000005370 alkoxysilyl group Chemical group 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 229910052570 clay Inorganic materials 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 239000003431 cross linking reagent Substances 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 150000001993 dienes Chemical class 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 125000001033 ether group Chemical group 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 125000001841 imino group Chemical group [H]N=* 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000012844 infrared spectroscopy analysis Methods 0.000 description 1
- 229920003049 isoprene rubber Polymers 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000010445 mica Substances 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000012763 reinforcing filler Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000004043 responsiveness Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 230000001953 sensory effect Effects 0.000 description 1
- 125000005372 silanol group Chemical group 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000008117 stearic acid Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 238000011191 terminal modification Methods 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 125000003396 thiol group Chemical group [H]S* 0.000 description 1
- ICJGKYTXBRDUMV-UHFFFAOYSA-N trichloro(6-trichlorosilylhexyl)silane Chemical compound Cl[Si](Cl)(Cl)CCCCCC[Si](Cl)(Cl)Cl ICJGKYTXBRDUMV-UHFFFAOYSA-N 0.000 description 1
- 239000004636 vulcanized rubber Substances 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/04—Carbon
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L15/00—Compositions of rubber derivatives
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L7/00—Compositions of natural rubber
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
- Y02T10/86—Optimisation of rolling resistance, e.g. weight reduction
Definitions
- the present invention mainly relates to a rubber composition for a tire intended to be used for an undertread portion of a pneumatic tire.
- tan ⁇ at 60° C. (hereinafter, referred to as “tan ⁇ (60° C.)”) measured by dynamic viscoelasticity is generally used, and tan ⁇ (60° C.) of the rubber composition is small. The lower the exothermicity, the less. Then, as a method of reducing tan ⁇ (60° C.) of the rubber composition, for example, it is possible to reduce the compounding amount of a filler such as carbon black or increase the particle size of carbon black. Alternatively, it has been proposed to blend silica (see, for example, Patent Document 1).
- the object of the present invention is a rubber composition for a tire intended mainly for use in the undertread portion of a pneumatic tire, which has low rolling resistance, and is excellent in steering stability and durability when formed into a tire. To provide a rubber composition for a tire.
- the rubber composition for a tire of the present invention which achieves the above object has a nitrogen adsorption specific surface area N with respect to 100 parts by mass of a rubber component containing 50% by mass or more of natural rubber and 35% by mass to 50% by mass of terminal-modified butadiene rubber.
- a rubber composition for a tire comprising 50 parts by mass or more of carbon black having 2 SA of 70 m 2 /g or less, having a hardness of 65 or more and a rebound resilience at 40° C. of 80% or more. To do.
- the rubber composition for a tire according to the present invention is a combination of a terminal modified butadiene rubber in addition to a natural rubber as a rubber component, and a carbon black having a large particle size is compounded as a filler, and the hardness and the impact resilience of the rubber composition. Is sufficiently increased as described above, it is possible to improve the steering stability and durability of the tire while reducing rolling resistance. In particular, since carbon black having a large particle size and terminal-modified butadiene rubber are used in combination, it is possible to increase the compounding amount of carbon black and improve the rubber hardness without deteriorating heat generation. The performance of can be improved in a balanced manner.
- the “hardness” is the hardness of the rubber composition measured by the durometer type A at a temperature of 20° C. according to JIS K6253.
- the “repulsion elastic modulus at 40° C.” is the repulsive elastic modulus of the rubber composition measured at a temperature of 40° C. by a Lupke type repulsion elasticity testing device according to JIS K6255.
- the molecular weight distribution (Mw/Mn) obtained from the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the terminal-modified butadiene rubber is preferably 2.0 or less.
- the rubber physical properties become better, and it is advantageous to reduce the rolling resistance and to improve the steering stability and durability of the tire.
- the "weight average molecular weight Mw" and the "number average molecular weight Mn” are measured by gel permeation chromatography (GPC) in terms of standard polystyrene.
- the terminal functional group of the terminal-modified butadiene rubber is at least one of a hydroxyl group, an amino group, an alkoxyl group, and an epoxy group. This increases the affinity with carbon black and further improves the dispersibility of carbon black, so it is possible to more effectively increase rubber hardness and adhesiveness while maintaining low exothermicity, and balance these performances. It is advantageous to be well balanced.
- the amine anti-aging agent it is preferable to add 1.0 to 4.0 parts by mass of the amine anti-aging agent to 100 parts by mass of the rubber component. Further, it is preferable to add more than 0 parts by mass and 2.0 parts by mass or less of wax to 100 parts by mass of the rubber component. By thus blending the antioxidant and wax, the crack resistance and workability can be improved.
- the rubber composition for a tire of the present invention is preferably used in the undertread portion of a pneumatic tire, and a pneumatic tire using the rubber composition for a tire of the present invention in the undertread portion has steering stability and durability. It is possible to improve fuel efficiency while maintaining good performance.
- the rubber component is a diene rubber, which always contains natural rubber and terminal-modified butadiene rubber.
- the natural rubber a rubber normally used in a rubber composition for tires can be used. By blending natural rubber, it is possible to obtain sufficient rubber strength as a rubber composition for tires.
- the content of the natural rubber is 50% by mass or more, preferably 50% by mass to 70% by mass, more preferably 60% by mass to 65% by mass. If the content of natural rubber is less than 50% by mass, the rubber strength will decrease.
- the terminal-modified butadiene rubber is a butadiene rubber modified with an organic compound having a functional group at one or both ends of the molecular chain.
- Examples of the functional group that modifies the terminal of the molecular chain include an alkoxysilyl group, a hydroxyl group (hydroxyl group), an aldehyde group, a carboxyl group, an amino group, an amide group, an imino group, an alkoxyl group, an epoxy group, an amide group, a thiol group, Examples thereof include ether groups and siloxane bonding groups. Among them, at least one selected from a hydroxyl group (hydroxyl group), an amino group, an amide group, an alkoxyl group, an epoxy group, and a siloxane bonding group is preferable.
- the siloxane bonding group is a functional group having a —O—Si—O— structure.
- the content of the terminal-modified butadiene rubber is 35% by mass to 50% by mass, preferably 40% by mass to 50% by mass. If the compounding amount of the terminal-modified butadiene rubber is less than 35% by mass, fuel economy is deteriorated. If the compounding amount of the terminal-modified butadiene rubber exceeds 50% by mass, the rubber strength will decrease.
- the molecular weight distribution (Mw/Mn) of the terminal-modified butadiene rubber is preferably 2.0 or less, more preferably 1.1 to 1.6. In this way, by using a terminal-modified butadiene rubber with a narrow molecular weight distribution, the rubber physical properties become better, and rolling resistance is reduced while effectively improving steering stability and durability when used as a tire. can do.
- Mw/Mn molecular weight distribution of the terminal-modified butadiene rubber exceeds 2.0, the hysteresis loss becomes large, the heat generation property of the rubber becomes large, and the compression set resistance decreases.
- the glass transition temperature Tg of the terminal-modified butadiene rubber used in the present invention is preferably ⁇ 85° C. or lower, more preferably ⁇ 90° C. to ⁇ 100° C. By setting the glass transition temperature Tg in this way, heat generation can be effectively reduced. When the glass transition temperature Tg exceeds ⁇ 80° C., the effect of reducing heat generation cannot be sufficiently obtained.
- the glass transition temperature Tg of natural rubber is not particularly limited, but can be set to, for example, ⁇ 70° C. to ⁇ 80° C.
- the terminal-modified butadiene rubber used in the present invention has a vinyl content of preferably 0.1% by mass to 20% by mass, more preferably 0.1% by mass to 15% by mass.
- the vinyl content of the terminal-modified butadiene rubber is less than 0.1% by mass, the affinity with carbon black is insufficient and it becomes difficult to sufficiently reduce heat generation.
- the vinyl content of the terminal-modified butadiene rubber exceeds 20% by mass, the glass transition temperature Tg of the rubber composition rises, and rolling resistance and abrasion resistance cannot be sufficiently improved.
- the vinyl unit content of the terminal-modified butadiene rubber is to be measured by infrared spectroscopic analysis (Hampton method).
- the increase/decrease in the vinyl unit content in the terminal-modified butadiene rubber can be appropriately adjusted by a usual method such as a catalyst.
- the tire rubber composition of the present invention may contain a diene rubber other than natural rubber and terminal-modified butadiene rubber.
- diene rubbers include, for example, butadiene rubber without terminal modification, styrene butadiene rubber, isoprene rubber, acrylonitrile-butadiene rubber and the like. These diene rubbers can be used alone or as an arbitrary blend.
- the tire rubber composition of the present invention always contains carbon black as a filler.
- carbon black used in the present invention has a nitrogen adsorption specific surface area N 2 SA of 70 m 2 /g or less, preferably 35 m 2 /g to 60 m 2 /g, and more preferably 35 m 2 /g to 50 m 2 /g. is there.
- N 2 SA nitrogen adsorption specific surface area
- the nitrogen adsorption specific surface area N 2 SA of carbon black exceeds 70 m 2 /g, the exothermic property deteriorates.
- the nitrogen adsorption specific surface area N 2 SA of carbon black is measured according to JIS 6217-2.
- the blending amount of carbon black is 50 parts by mass or more, preferably 55 parts by mass to 65 parts by mass, and more preferably 57 parts by mass to 60 parts by mass with respect to 100 parts by mass of the above rubber component. If the blending amount of the filler is less than 50 parts by mass, the hardness will decrease.
- the rubber composition of the present invention may contain an inorganic filler other than carbon black.
- inorganic fillers include silica, clay, talc, calcium carbonate, mica, aluminum hydroxide and the like.
- the weight ratio of silica to carbon black is preferably 0.1 to 0.5, more preferably 0.15 to 0.3. Good to do. If the weight ratio is out of the above range, the effect of increasing the rubber hardness while maintaining the low exothermicity cannot be obtained. In particular, if the weight ratio of silica is too large, the exothermicity may deteriorate.
- the total amount of the fillers is preferably 70 parts by mass or less, more preferably 55 parts by mass to 60 parts by mass. If the total amount of the fillers is more than 75 parts by mass, heat generation may be deteriorated. From the relationship between the above blending amount and the weight ratio, when silica is used in combination, the blending amount of silica is preferably 5 parts by mass to 20 parts by mass, more preferably 5 parts by mass with respect to 100 parts by mass of the diene rubber. Parts to 10 parts by mass.
- the CTAB adsorption specific surface area of silica is preferably 100 m 2 /g to 250 m 2 /g, more preferably 135 m 2 /g to 210 m 2 /g. If the CTAB adsorption specific surface area of silica is less than 100 m 2 /g, the rubber strength will decrease. When the CTAB adsorption specific surface area of silica exceeds 250 m 2 /g, the heat generation property deteriorates. In the present invention, the CTAB adsorption specific surface area of silica shall be measured in accordance with ISO 5794.
- an amine anti-aging agent and/or wax By compounding these, crack resistance and workability can be improved.
- the compounding amount of the amine anti-aging agent is preferably 1.0 part by mass to 4.0 parts by mass, and more preferably 1.5 parts by mass to 3.5 parts by mass with respect to 100 parts by mass of the rubber component.
- the blending amount of the wax is preferably more than 0 parts by mass and 2.0 parts by mass or less, more preferably 0.1 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the rubber component, and an amine-based antioxidant and a wax. May be blended alone or in combination.
- the amount of the amine-based antioxidant is less than 1.0 part by mass, the effect of improving the crack resistance and workability cannot be expected, and especially the crack resistance is lowered. If the compounding amount of the amine anti-aging agent exceeds 4.0 parts by mass, the workability is deteriorated. If the amount of the wax compounded exceeds 2.0 parts by mass, the processability will decrease.
- compounding agents may be added to the rubber composition for tires of the present invention.
- Other compounding agents include reinforcing fillers other than carbon black and silica, vulcanization or crosslinking agents, vulcanization accelerators, antioxidants other than amines, liquid polymers, thermosetting resins, and thermoplastic resins.
- Various compounding agents generally used for pneumatic tires can be exemplified.
- the compounding amount of these compounding agents may be a conventional general compounding amount as long as the object of the present invention is not violated.
- kneading machine a usual kneading machine for rubber, for example, Banbury mixer, kneader, roll or the like can be used.
- the hardness of the rubber composition for a tire of the present invention having such a composition is 65 or more, preferably 65 to 75, more preferably 65 to 70.
- the impact resilience at 40° C. of the rubber composition for a tire of the present invention is 80% or more, preferably 80% to 85%, more preferably 82% to 85%. Since the rubber composition of the present invention has such physical properties, it is possible to improve rolling stability and durability of the tire while reducing rolling resistance. When the hardness is less than 65, the steering stability when used as a tire is deteriorated. When the impact resilience is less than 80%, heat generation is deteriorated and the rolling resistance cannot be reduced.
- the hardness and the impact resilience are not determined only by the above-mentioned composition, but are physical properties that can be adjusted by the kneading conditions and the kneading method.
- the rubber composition for a tire of the present invention can improve rolling stability and durability when being made into a tire while reducing rolling resistance due to the above-mentioned composition and physical properties.
- end-modified butadiene rubber is used in combination, and carbon black having a large particle size is blended as a filler, and carbon black having a large particle size and terminal-modified butadiene rubber are combined.
- carbon black having a large particle size is blended as a filler, and carbon black having a large particle size and terminal-modified butadiene rubber are combined.
- the hardness and impact resilience of the rubber composition are sufficiently increased as described above, it is possible to improve the steering stability and durability of the tire while reducing rolling resistance. Therefore, these performances can be improved in a well-balanced manner.
- the rubber composition for a tire of the present invention is preferably used in the undertread portion of a pneumatic tire, and the pneumatic tire using the rubber composition for a tire of the present invention in the undertread portion has steering stability and durability. Fuel economy performance can be improved while maintaining good performance.
- the hardness of the rubber composition was measured at a temperature of 20° C. by a durometer type A in accordance with JIS K6253. Further, the impact resilience of the rubber composition was measured at a temperature of 40° C. by a Lupke impact resilience tester in accordance with JIS K6255.
- the obtained rubber composition was evaluated for fuel efficiency, steering stability, durability, crack resistance, and workability by the methods shown below.
- a test tire (tire size 215/45R17) using the obtained rubber composition as an undertread was prepared and mounted on a standard rim (rim size 7JJ) to an air pressure of 230 kPa and an indoor drum tester (drum diameter). : 1707 mm) and rolling at a speed of 80 km/h while being pressed against the drum under a load equivalent to 85% of the maximum load under the air pressure described in JATMA Yearbook 2009 The resistance was measured. The evaluation result was shown by an index with the value of Standard Example 1 being 100, using the reciprocal of the measured value. The larger the index value, the smaller the rolling resistance and the better the fuel economy performance.
- a test driver conducted a sensory evaluation on the road surface responsiveness when changing the lane at the time of running and traveling 80 km/h on a test course consisting of a paved road surface. The evaluation results are shown by index values with the standard example 1 being 100. The larger this index value, the better the road surface response at the time of lane change, and the better the steering stability.
- Durability A test tire (tire size 215/45R17) in which the obtained rubber composition was used as an undertread was prepared, mounted on a standard rim (rim size 7JJ), the air pressure was set to 230 kPa, and mounted on a test vehicle of displacement 2000 cc. Then, the car was run on an 8-shaped turning test course under conditions of a turning acceleration of 0.8 G and 500 laps, and the amount of wear of the tread portion after running was measured. The evaluation results are shown by an index with the standard example 1 being 100, using the reciprocal of the measured value. The larger the index value, the smaller the amount of wear and the more excellent the durability.
- the obtained rubber composition was extruded into a sheet, and two extrudates (sample for crimping) 3 hours after the extruding were subjected to a crimping load of 0.98 N, a crimping time of 0 seconds, and a crimping speed of 50 cm/min. After press-bonding under the conditions, the film was peeled under the condition of a peeling speed of 125 cm/min, and the adhesive force at that time was measured by a PICMA type tack meter (manufactured by Toyo Seiki Seisaku-sho, Ltd.). The evaluation results are shown in AC below.
- the "tack index” used for the evaluation of A to C is an index with the measured value as standard example 1 being 100.
- Tables 1 and 2 The types of raw materials used in Tables 1 and 2 are shown below.
- -NR natural rubber
- TSR20 glass transition temperature Tg: -65°C
- SBR styrene butadiene rubber
- Nipol 1502 glass transition temperature: -60°C
- -Modified S-SBR Terminal-modified solution-polymerized styrene-butadiene rubber
- Nipol NS612 manufactured by Nippon Zeon Co., Ltd.
- BR butadiene rubber
- Nipol BR1220 manufactured by Zeon Corporation (glass transition temperature Tg: -105°C)
- -Modified BR1 end-modified butadiene rubber
- JSR BR54 glass transition temperature Tg: -107°C, functional group: silanol group, molecular weight distribution 2.5
- Modified BR2 terminal modified butadiene rubber synthesized by the following method (glass transition temperature Tg: -93°C, functional group: polyorganosiloxane group)
- BR3 end-modified butadiene rubber, Nipol BR1250H manufactured by Nippon Zeon Co., Ltd.
- CB1 Carbon black, Tokai Carbon Co., Ltd., Seast KHP (nitrogen adsorption specific surface area N 2 SA: 85 m 2 /g)
- CB2 carbon black, Niteron #GN (Nitrogen adsorption specific surface area N 2 SA: 35 m 2 /g) manufactured by Shin Nikka Carbon Co., Ltd.
- Silica Ultrasil VN3 (CTAB adsorption specific surface area: 153 m 2 /g) manufactured by Degussa ⁇ Zinc oxide: Three types of zinc oxide manufactured by Shodo Chemical Industry ⁇ Stearic acid: Lunac S-25 manufactured by Kao -Anti-aging agent 1: amine-based anti-aging agent, Santoflex 6PPD manufactured by Flexis -Anti-aging agent 2: amine-ketone type anti-aging agent, Nocrac 224 manufactured by Ouchi Shinko Chemical Industry Co., Ltd. ⁇ Wax: Ouchi Shinko Chemical Co., Ltd. Sannok Sulfur: Shikoku Kasei Co., Ltd. Mucron OT-20 ⁇ Vulcanization accelerator: Nocceller CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
- the maximum temperature during the polymerization reaction was 80°C. After the continuous addition was completed, the polymerization reaction was continued for another 15 minutes, and after confirming that the polymerization conversion rate was in the range of 95% to 100%, a small amount of the polymerization solution was sampled. A small amount of the sampled polymerization solution was quenched by adding excess methanol and then air-dried to obtain a polymer, which was used as a sample for gel permeation chromatography (GPC) analysis. Using the sample, the peak top molecular weight and the molecular weight distribution of the polymer (corresponding to a conjugated diene-based polymer chain having an active end) were measured and found to be "230,000" and "1.04", respectively.
- GPC gel permeation chromatography
- the styrene-butadiene rubber was blended in place of the terminal-modified butadiene rubber, so the fuel economy performance deteriorated.
- the terminal-modified solution-polymerized styrene-butadiene rubber was blended in place of the terminal-modified butadiene rubber, so the durability was deteriorated.
- the rubber composition (tire) of Comparative Example 3 was poor in durability because the compounding amount of the terminal-modified butadiene rubber was too small.
- the steering stability and durability deteriorated because the amount of carbon black blended was too small.
- the rubber composition (tire) of Comparative Example 5 contained not only natural rubber and terminal-modified butadiene rubber but also styrene-butadiene rubber, and thus the impact resilience deteriorated.
- the rubber composition (tire) of Comparative Example 7 had too low a hardness, and thus had poor steering stability.
- the rubber composition (tire) of Comparative Example 8 had a too small impact resilience, and thus the fuel efficiency was deteriorated.
- the rubber composition (tire) of Comparative Example 9 does not contain the terminal-modified butadiene rubber, it is not possible to obtain the effect of improving the fuel economy performance and the steering stability performance, and further, only the non-amine-based antioxidant is blended. Therefore, the crack resistance and durability deteriorated.
- the rubber composition (tire) of Comparative Example 10 since the terminal-modified butadiene rubber was not blended, it was not possible to obtain the effect of improving the fuel economy performance, the steering stability performance, and the durability, and further, the antioxidant content was large. Since it was too much, workability deteriorated.
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Abstract
Provided is a rubber composition for tires which is intended mainly for use in producing the undertread part of a pneumatic tire and which gives tires having low rolling resistance and excellent in terms of steering stability and durability. Carbon black having a nitrogen-adsorption specific surface area N2SA of 70 m2/g or smaller is incorporated in an amount of 50 parts by mass or more into 100 parts by mass of a rubber ingredient comprising 50 mass% or more natural rubber and 35-50 mass% terminal-modified butadiene rubber, and the rubber composition is made to have a hardness set at 65 or higher and a 40°C resilience set at 80% or higher.
Description
本発明は、主に空気入りタイヤのアンダートレッド部に用いることを意図したタイヤ用ゴム組成物に関する。
The present invention mainly relates to a rubber composition for a tire intended to be used for an undertread portion of a pneumatic tire.
空気入りタイヤにおいては、環境負荷を低減するために走行時の燃費性能を向上することが求められている。そのため、空気入りタイヤの各部を構成するゴム組成物の発熱を抑制することが行われている。近年、燃費性能の更なる改善のために、例えば、空気入りタイヤの踏面を形成するキャップトレッド部の内側に配置されるアンダートレッド部を構成するゴム組成物についても発熱を抑制することが求められている。
In pneumatic tires, it is required to improve fuel efficiency during running to reduce the environmental load. Therefore, heat generation of the rubber composition forming each part of the pneumatic tire is suppressed. In recent years, in order to further improve fuel efficiency, for example, it is required to suppress heat generation in a rubber composition that constitutes an undertread portion arranged inside a cap tread portion that forms a tread surface of a pneumatic tire. ing.
ゴム組成物の発熱性の指標としては、一般に動的粘弾性測定による６０℃におけるｔａｎδ（以下、「ｔａｎδ（６０℃）」という。）が用いられ、ゴム組成物のｔａｎδ（６０℃）が小さいほど発熱性が小さくなる。そして、ゴム組成物のｔａｎδ（６０℃）を小さくする方法として、例えばカーボンブラック等の充填材の配合量を少なくしたり、カーボンブラックの粒径を大きくすることが挙げられる。或いは、シリカを配合することも提案されている（例えば特許文献１を参照）。しかしながら、これらの方法では、必ずしもゴム硬度や耐疲労性が十分に得られず、タイヤに利用したとき（特に、アンダートレッド部に用いたとき）に、操縦安定性や耐久性への影響が懸念される。そのため、アンダートレッド部として用いることを意図したタイヤ用ゴム組成物において、タイヤにした時の操縦安定性や耐久性を良好に維持しながら、低転がり性を向上する更なる対策が求められている。
As an index of exothermicity of the rubber composition, tan δ at 60° C. (hereinafter, referred to as “tan δ (60° C.)”) measured by dynamic viscoelasticity is generally used, and tan δ (60° C.) of the rubber composition is small. The lower the exothermicity, the less. Then, as a method of reducing tan δ (60° C.) of the rubber composition, for example, it is possible to reduce the compounding amount of a filler such as carbon black or increase the particle size of carbon black. Alternatively, it has been proposed to blend silica (see, for example, Patent Document 1). However, these methods do not always provide sufficient rubber hardness and fatigue resistance, and there is concern about the influence on steering stability and durability when used in tires (particularly when used in the undertread portion). To be done. Therefore, in a rubber composition for a tire intended to be used as an undertread portion, further measures are required to improve low rolling performance while maintaining good steering stability and durability when used as a tire. ..
本発明の目的は、主に空気入りタイヤのアンダートレッド部に用いることを意図したタイヤ用ゴム組成物であって、転がり抵抗が低く、且つ、タイヤにした時の操縦安定性や耐久性に優れるタイヤ用ゴム組成物を提供することにある。
The object of the present invention is a rubber composition for a tire intended mainly for use in the undertread portion of a pneumatic tire, which has low rolling resistance, and is excellent in steering stability and durability when formed into a tire. To provide a rubber composition for a tire.
上記目的を達成する本発明のタイヤ用ゴム組成物は、天然ゴム５０質量％以上と末端変性ブタジエンゴム３５質量％～５０質量％とを含むゴム成分１００質量部に対して、窒素吸着比表面積Ｎ2 ＳＡが７０ｍ2 ／ｇ以下であるカーボンブラックが５０質量部以上配合されたタイヤ用ゴム組成物であって、硬度が６５以上、４０℃における反発弾性率が８０％以上であることを特徴とする。
The rubber composition for a tire of the present invention which achieves the above object has a nitrogen adsorption specific surface area N with respect to 100 parts by mass of a rubber component containing 50% by mass or more of natural rubber and 35% by mass to 50% by mass of terminal-modified butadiene rubber. A rubber composition for a tire, comprising 50 parts by mass or more of carbon black having 2 SA of 70 m 2 /g or less, having a hardness of 65 or more and a rebound resilience at 40° C. of 80% or more. To do.
本発明のタイヤ用ゴム組成物は、ゴム成分として天然ゴムに加えて末端変性ブタジエンゴムを併用し、且つ、充填材として粒径の大きいカーボンブラックを配合し、ゴム組成物の硬度や反発弾性率を上記のように充分に高めているので、転がり抵抗を低減しながら、タイヤにした時の操縦安定性や耐久性を向上することができる。特に、粒径の大きいカーボンブラックと末端変性ブタジエンゴムとを組み合わせて用いているので、発熱を悪化させずに、カーボンブラックの配合量を増大してゴム硬度を向上することも可能になり、前述の性能をバランスよく改善することができる。
The rubber composition for a tire according to the present invention is a combination of a terminal modified butadiene rubber in addition to a natural rubber as a rubber component, and a carbon black having a large particle size is compounded as a filler, and the hardness and the impact resilience of the rubber composition. Is sufficiently increased as described above, it is possible to improve the steering stability and durability of the tire while reducing rolling resistance. In particular, since carbon black having a large particle size and terminal-modified butadiene rubber are used in combination, it is possible to increase the compounding amount of carbon black and improve the rubber hardness without deteriorating heat generation. The performance of can be improved in a balanced manner.
尚、本発明において、「硬度」とは、ＪＩＳ Ｋ６２５３に準拠して、デュロメータのタイプＡにより温度２０℃で測定したゴム組成物の硬度である。また、「４０℃における反発弾性率」とは、ＪＩＳ Ｋ６２５５に準拠して、リュプケ式反発弾性試験装置により温度４０℃で測定したゴム組成物の反発弾性率である。
In the present invention, the “hardness” is the hardness of the rubber composition measured by the durometer type A at a temperature of 20° C. according to JIS K6253. Further, the “repulsion elastic modulus at 40° C.” is the repulsive elastic modulus of the rubber composition measured at a temperature of 40° C. by a Lupke type repulsion elasticity testing device according to JIS K6255.
本発明では、末端変性ブタジエンゴムの重量平均分子量（Ｍｗ）および数平均分子量（Ｍｎ）から求められる分子量分布（Ｍｗ／Ｍｎ）が２．０以下であることが好ましい。このように分子量分布を狭くすることで、ゴム物性がより良好になり、転がり抵抗を低減しながら、タイヤにした時の操縦安定性や耐久性を向上するには有利になる。尚、本発明において、「重量平均分子量Ｍｗ」と「数平均分子量Ｍｎ」とは、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）により標準ポリスチレン換算により測定するものとする。
In the present invention, the molecular weight distribution (Mw/Mn) obtained from the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the terminal-modified butadiene rubber is preferably 2.0 or less. By narrowing the molecular weight distribution in this way, the rubber physical properties become better, and it is advantageous to reduce the rolling resistance and to improve the steering stability and durability of the tire. In the present invention, the "weight average molecular weight Mw" and the "number average molecular weight Mn" are measured by gel permeation chromatography (GPC) in terms of standard polystyrene.
本発明では、末端変性ブタジエンゴムの末端の官能基が水酸基、アミノ基、アルコキシル基、エポキシ基のうちの少なくとも１種であることが好ましい。これによりカーボンブラックとの親和性が高まり、カーボンブラックの分散性がより改善されるので、より効果的に、発熱性を低く維持しながらゴム硬度や接着性を高めることができ、これら性能をバランスよく両立するには有利になる。
In the present invention, it is preferable that the terminal functional group of the terminal-modified butadiene rubber is at least one of a hydroxyl group, an amino group, an alkoxyl group, and an epoxy group. This increases the affinity with carbon black and further improves the dispersibility of carbon black, so it is possible to more effectively increase rubber hardness and adhesiveness while maintaining low exothermicity, and balance these performances. It is advantageous to be well balanced.
本発明では、ゴム成分１００質量部に対してアミン系老化防止剤を１．０質量部～４．０質量部配合することが好ましい。また、ゴム成分１００質量部に対してワックスを０質量部超２．０質量部以下配合することが好ましい。このように老化防止剤やワックスを配合することで、耐クラック性や加工性を向上することができる。
In the present invention, it is preferable to add 1.0 to 4.0 parts by mass of the amine anti-aging agent to 100 parts by mass of the rubber component. Further, it is preferable to add more than 0 parts by mass and 2.0 parts by mass or less of wax to 100 parts by mass of the rubber component. By thus blending the antioxidant and wax, the crack resistance and workability can be improved.
本発明のタイヤ用ゴム組成物は、空気入りタイヤのアンダートレッド部に用いることが好ましく、本発明のタイヤ用ゴム組成物をアンダートレッド部に用いた空気入りタイヤは、操縦安定性や耐久性を良好に維持しながら、燃費性能を向上することができる。
The rubber composition for a tire of the present invention is preferably used in the undertread portion of a pneumatic tire, and a pneumatic tire using the rubber composition for a tire of the present invention in the undertread portion has steering stability and durability. It is possible to improve fuel efficiency while maintaining good performance.
本発明のタイヤ用ゴム組成物において、ゴム成分はジエン系ゴムであり、天然ゴムと末端変性ブタジエンゴムとを必ず含む。
In the rubber composition for tires of the present invention, the rubber component is a diene rubber, which always contains natural rubber and terminal-modified butadiene rubber.
天然ゴムとしては、タイヤ用ゴム組成物に通常用いられるゴムを使用することができる。天然ゴムを配合することで、タイヤ用ゴム組成物として充分なゴム強度を得ることができる。ジエン系ゴム全体を１００質量％としたとき、天然ゴムの配合量は５０質量％以上、好ましくは５０質量％～７０質量％、より好ましくは６０質量％～６５質量％である。天然ゴムの配合量が５０質量％未満であるとゴム強度が低下する。
As the natural rubber, a rubber normally used in a rubber composition for tires can be used. By blending natural rubber, it is possible to obtain sufficient rubber strength as a rubber composition for tires. When the total amount of the diene rubber is 100% by mass, the content of the natural rubber is 50% by mass or more, preferably 50% by mass to 70% by mass, more preferably 60% by mass to 65% by mass. If the content of natural rubber is less than 50% by mass, the rubber strength will decrease.
末端変性ブタジエンゴムは、分子鎖の片末端または両末端が官能基を有する有機化合物で変性されたブタジエンゴムである。このような末端変性ブタジエンゴムを配合することにより、後述のカーボンブラックとの親和性を高くし分散性を改善するため、発熱性を低く維持しながら、カーボンブラックの作用効果を一層向上して、ゴム硬度を高めることができる。分子鎖の末端を変性する官能基としては、例えばアルコキシシリル基、ヒドロキシル基（水酸基）、アルデヒド基、カルボキシル基、アミノ基、アミド基、イミノ基、アルコキシル基、エポキシ基、アミド基、チオール基、エーテル基、シロキサン結合基を挙げることができる。なかでもヒドロキシル基（水酸基）、アミノ基、アミド基、アルコキシル基、エポキシ基、シロキサン結合基から選ばれる少なくとも一つであるとよい。ここで、シロキサン結合基は、－Ｏ－Ｓｉ－Ｏ－構造を有する官能基とする。
The terminal-modified butadiene rubber is a butadiene rubber modified with an organic compound having a functional group at one or both ends of the molecular chain. By blending such a terminal-modified butadiene rubber, the affinity with the carbon black described later is increased and the dispersibility is improved, so that the action effect of the carbon black is further improved while keeping the exothermicity low. The rubber hardness can be increased. Examples of the functional group that modifies the terminal of the molecular chain include an alkoxysilyl group, a hydroxyl group (hydroxyl group), an aldehyde group, a carboxyl group, an amino group, an amide group, an imino group, an alkoxyl group, an epoxy group, an amide group, a thiol group, Examples thereof include ether groups and siloxane bonding groups. Among them, at least one selected from a hydroxyl group (hydroxyl group), an amino group, an amide group, an alkoxyl group, an epoxy group, and a siloxane bonding group is preferable. Here, the siloxane bonding group is a functional group having a —O—Si—O— structure.
ジエン系ゴム全体を１００質量％としたとき、末端変性ブタジエンゴムの配合量は、３５質量％～５０質量％、好ましくは４０質量％～５０質量％である。末端変性ブタジエンゴムの配合量が３５質量％未満であると低燃費性が悪化する。末端変性ブタジエンゴムの配合量が５０質量％を超えるとゴム強度が低下する。
When the total amount of the diene rubber is 100% by mass, the content of the terminal-modified butadiene rubber is 35% by mass to 50% by mass, preferably 40% by mass to 50% by mass. If the compounding amount of the terminal-modified butadiene rubber is less than 35% by mass, fuel economy is deteriorated. If the compounding amount of the terminal-modified butadiene rubber exceeds 50% by mass, the rubber strength will decrease.
末端変性ブタジエンゴムの分子量分布（Ｍｗ／Ｍｎ）は、好ましくは２．０以下、より好ましくは１．１～１．６である。このように、末端変性ブタジエンゴムとして分子量分布が狭いものを用いることで、ゴム物性がより良好になり、転がり抵抗を低減しながら、タイヤにした時の操縦安定性や耐久性を効果的に向上することができる。末端変性ブタジエンゴムの分子量分布（Ｍｗ／Ｍｎ）が２．０を超えるとヒステリシスロスが大きくなってゴムの発熱性が大きくなると共に、耐コンプレッションセット性が低下する。
The molecular weight distribution (Mw/Mn) of the terminal-modified butadiene rubber is preferably 2.0 or less, more preferably 1.1 to 1.6. In this way, by using a terminal-modified butadiene rubber with a narrow molecular weight distribution, the rubber physical properties become better, and rolling resistance is reduced while effectively improving steering stability and durability when used as a tire. can do. When the molecular weight distribution (Mw/Mn) of the terminal-modified butadiene rubber exceeds 2.0, the hysteresis loss becomes large, the heat generation property of the rubber becomes large, and the compression set resistance decreases.
本発明で使用する末端変性ブタジエンゴムのガラス転移温度Ｔｇは好ましくは－８５℃以下、より好ましくは－９０℃～－１００℃であるとよい。このようにガラス転移温度Ｔｇを設定することで、発熱性を効果的に低減することができる。ガラス転移温度Ｔｇが－８０℃を超えると発熱性を低減する効果が充分に得られなくなる。尚、天然ゴムのガラス転移温度Ｔｇは特に限定されないが、例えば－７０℃～－８０℃に設定することができる。
The glass transition temperature Tg of the terminal-modified butadiene rubber used in the present invention is preferably −85° C. or lower, more preferably −90° C. to −100° C. By setting the glass transition temperature Tg in this way, heat generation can be effectively reduced. When the glass transition temperature Tg exceeds −80° C., the effect of reducing heat generation cannot be sufficiently obtained. The glass transition temperature Tg of natural rubber is not particularly limited, but can be set to, for example, −70° C. to −80° C.
本発明で使用する末端変性ブタジエンゴムは、ビニル含有量が好ましくは０．１質量％～２０質量％、より好ましくは０．１質量％～１５質量％である。末端変性ブタジエンゴムのビニル含有量が０．１質量％未満であると、カーボンブラックとの親和性が不足し発熱を充分に低減することが難しくなる。末端変性ブタジエンゴムのビニル含有量が２０質量％を超えると、ゴム組成物のガラス転移温度Ｔｇが上昇し、転がり抵抗および耐摩耗性を十分に改良することができない。尚、末端変性ブタジエンゴムのビニル単位含有量は赤外分光分析（ハンプトン法）により測定するものとする。末端変性ブタジエンゴムにおけるビニル単位含有量の増減は、触媒等、通常の方法で適宜調製することができる。
The terminal-modified butadiene rubber used in the present invention has a vinyl content of preferably 0.1% by mass to 20% by mass, more preferably 0.1% by mass to 15% by mass. When the vinyl content of the terminal-modified butadiene rubber is less than 0.1% by mass, the affinity with carbon black is insufficient and it becomes difficult to sufficiently reduce heat generation. When the vinyl content of the terminal-modified butadiene rubber exceeds 20% by mass, the glass transition temperature Tg of the rubber composition rises, and rolling resistance and abrasion resistance cannot be sufficiently improved. The vinyl unit content of the terminal-modified butadiene rubber is to be measured by infrared spectroscopic analysis (Hampton method). The increase/decrease in the vinyl unit content in the terminal-modified butadiene rubber can be appropriately adjusted by a usual method such as a catalyst.
本発明のタイヤ用ゴム組成物は、天然ゴム、末端変性ブタジエンゴム以外の他のジエン系ゴムを含有してもよい。他のジエン系ゴムとしては、例えば、末端変性していないブタジエンゴム、スチレンブタジエンゴム、イソプレンゴム、アクリロニトリル‐ブタジエンゴム等が挙げられる。これらジエン系ゴムは、単独又は任意のブレンドとして使用することができる。
The tire rubber composition of the present invention may contain a diene rubber other than natural rubber and terminal-modified butadiene rubber. Other diene rubbers include, for example, butadiene rubber without terminal modification, styrene butadiene rubber, isoprene rubber, acrylonitrile-butadiene rubber and the like. These diene rubbers can be used alone or as an arbitrary blend.
本発明のタイヤ用ゴム組成物は、充填剤としてカーボンブラックが必ず配合される。カーボンブラックを配合することでゴム組成物の強度を高めることができる。特に、本発明で使用するカーボンブラックは、窒素吸着比表面積Ｎ2 ＳＡが７０ｍ2 ／ｇ以下、好ましくは３５ｍ2 ／ｇ～６０ｍ2 ／ｇ、より好ましくは３５ｍ2 ／ｇ～５０ｍ2 ／ｇである。このように粒径が大きいカーボンブラックを上述の変性ブタジエンゴムと組み合わせて配合することで、発熱性を低く維持しながら、ゴム硬度を効果的に高めることができる。カーボンブラックの窒素吸着比表面積Ｎ2 ＳＡが７０ｍ2 ／ｇを超えると発熱性が悪化する。尚、本発明において、カーボンブラックの窒素吸着比表面積Ｎ2 ＳＡは、ＪＩＳ６２１７‐２に準拠して測定するものとする。
The tire rubber composition of the present invention always contains carbon black as a filler. By blending carbon black, the strength of the rubber composition can be increased. Particularly, the carbon black used in the present invention has a nitrogen adsorption specific surface area N 2 SA of 70 m 2 /g or less, preferably 35 m 2 /g to 60 m 2 /g, and more preferably 35 m 2 /g to 50 m 2 /g. is there. By blending carbon black having such a large particle diameter in combination with the above-mentioned modified butadiene rubber, it is possible to effectively increase the rubber hardness while keeping the heat generation property low. When the nitrogen adsorption specific surface area N 2 SA of carbon black exceeds 70 m 2 /g, the exothermic property deteriorates. In the present invention, the nitrogen adsorption specific surface area N 2 SA of carbon black is measured according to JIS 6217-2.
カーボンブラックの配合量は、上述のゴム成分１００質量部に対して、５０質量部以上、好ましくは５５質量部～６５質量部、より好ましくは５７質量部～６０質量部である。充填剤の配合量が５０質量部未満であると硬度が低下する。
The blending amount of carbon black is 50 parts by mass or more, preferably 55 parts by mass to 65 parts by mass, and more preferably 57 parts by mass to 60 parts by mass with respect to 100 parts by mass of the above rubber component. If the blending amount of the filler is less than 50 parts by mass, the hardness will decrease.
本発明のゴム組成物は、カーボンブラック以外の他の無機充填剤を配合することができる。他の無機充填剤としては、例えばシリカ、クレー、タルク、炭酸カルシウム、マイカ、水酸化アルミニウム等を例示することができる。
The rubber composition of the present invention may contain an inorganic filler other than carbon black. Examples of other inorganic fillers include silica, clay, talc, calcium carbonate, mica, aluminum hydroxide and the like.
これら他の無機充填剤のなかでも、特にシリカを併用する場合、カーボンブラックに対するシリカの重量比率を好ましくは０．１～０．５、より好ましくは０．１５～０．３になるように配合するとよい。この重量比率が上記範囲から外れると、発熱性を低く維持しながらゴム硬度を高める効果が得られない。特に、シリカの重量比率が過多であると発熱性が悪化する虞がある。
Among these other inorganic fillers, when silica is used in combination, the weight ratio of silica to carbon black is preferably 0.1 to 0.5, more preferably 0.15 to 0.3. Good to do. If the weight ratio is out of the above range, the effect of increasing the rubber hardness while maintaining the low exothermicity cannot be obtained. In particular, if the weight ratio of silica is too large, the exothermicity may deteriorate.
充填剤としてシリカを併用する場合、充填材の総配合量は好ましくは７０質量部以下、より好ましくは５５質量部～６０質量部にするとよい。充填材の総配合量が７５質量部を超えると発熱性が悪化する虞がある。尚、上述の配合量と重量比率との関係から、シリカを併用する場合のシリカの配合量は、ジエン系ゴム１００質量部に対して好ましくは５質量部～２０質量部、より好ましくは５質量部～１０質量部である。
When silica is also used as a filler, the total amount of the fillers is preferably 70 parts by mass or less, more preferably 55 parts by mass to 60 parts by mass. If the total amount of the fillers is more than 75 parts by mass, heat generation may be deteriorated. From the relationship between the above blending amount and the weight ratio, when silica is used in combination, the blending amount of silica is preferably 5 parts by mass to 20 parts by mass, more preferably 5 parts by mass with respect to 100 parts by mass of the diene rubber. Parts to 10 parts by mass.
充填剤としてシリカを併用する場合、シリカのＣＴＡＢ吸着比表面積は好ましくは１００ｍ2 ／ｇ～２５０ｍ2 ／ｇ、より好ましくは１３５ｍ2 ／ｇ～２１０ｍ2 ／ｇであるとよい。シリカのＣＴＡＢ吸着比表面積が１００ｍ2 ／ｇ未満であるとゴム強度が低下する。シリカのＣＴＡＢ吸着比表面積が２５０ｍ2 ／ｇを超えると発熱性が悪化する。尚、本発明において、シリカのＣＴＡＢ吸着比表面積は、ＩＳＯ ５７９４に準拠して測定するものとする。
When silica is also used as a filler, the CTAB adsorption specific surface area of silica is preferably 100 m 2 /g to 250 m 2 /g, more preferably 135 m 2 /g to 210 m 2 /g. If the CTAB adsorption specific surface area of silica is less than 100 m 2 /g, the rubber strength will decrease. When the CTAB adsorption specific surface area of silica exceeds 250 m 2 /g, the heat generation property deteriorates. In the present invention, the CTAB adsorption specific surface area of silica shall be measured in accordance with ISO 5794.
本発明では、アミン系老化防止剤および／またはワックスを配合することが好ましい。これらを配合することで、耐クラック性や加工性を向上することができる。アミン系老化防止剤の配合量は、ゴム成分１００質量部に対して好ましくは１．０質量部～４．０質量部、より好ましくは１．５質量部～３．５質量部である。ワックスの配合量は、ゴム成分１００質量部に対して好ましくは０質量部超２．０質量部以下、より好ましくは０．１質量部以上２．０質量部以下アミン系老化防止剤とワックスとは、それぞれ単独で配合してもよく、併用してもよい。アミン系老化防止剤の配合量が１．０質量部未満であると、耐クラック性や加工性を向上する効果が見込めなくなり、特に耐クラック性が低下する。アミン系老化防止剤の配合量が４．０質量部を超えると加工性が低下する。ワックスの配合量が２．０質量部を超えると加工性が低下する。
In the present invention, it is preferable to add an amine anti-aging agent and/or wax. By compounding these, crack resistance and workability can be improved. The compounding amount of the amine anti-aging agent is preferably 1.0 part by mass to 4.0 parts by mass, and more preferably 1.5 parts by mass to 3.5 parts by mass with respect to 100 parts by mass of the rubber component. The blending amount of the wax is preferably more than 0 parts by mass and 2.0 parts by mass or less, more preferably 0.1 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the rubber component, and an amine-based antioxidant and a wax. May be blended alone or in combination. If the amount of the amine-based antioxidant is less than 1.0 part by mass, the effect of improving the crack resistance and workability cannot be expected, and especially the crack resistance is lowered. If the compounding amount of the amine anti-aging agent exceeds 4.0 parts by mass, the workability is deteriorated. If the amount of the wax compounded exceeds 2.0 parts by mass, the processability will decrease.
本発明のタイヤ用ゴム組成物には、上記以外の他の配合剤を添加することができる。他の配合剤としては、カーボンブラックおよびシリカ以外の他の補強性充填剤、加硫又は架橋剤、加硫促進剤、アミン系以外の老化防止剤、液状ポリマー、熱硬化性樹脂、熱可塑性樹脂など、一般的に空気入りタイヤに使用される各種配合剤を例示することができる。これら配合剤の配合量は本発明の目的に反しない限り、従来の一般的な配合量にすることができる。また混練機としは、通常のゴム用混練機械、例えば、バンバリーミキサー、ニーダー、ロール等を使用することができる。
Other compounding agents than the above may be added to the rubber composition for tires of the present invention. Other compounding agents include reinforcing fillers other than carbon black and silica, vulcanization or crosslinking agents, vulcanization accelerators, antioxidants other than amines, liquid polymers, thermosetting resins, and thermoplastic resins. Various compounding agents generally used for pneumatic tires can be exemplified. The compounding amount of these compounding agents may be a conventional general compounding amount as long as the object of the present invention is not violated. As the kneading machine, a usual kneading machine for rubber, for example, Banbury mixer, kneader, roll or the like can be used.
このような配合からなる本発明のタイヤ用ゴム組成物の硬度は６５以上、好ましくは６５～７５、より好ましくは６５～７０である。また、本発明のタイヤ用ゴム組成物の４０℃における反発弾性率は８０％以上、好ましくは８０％～８５％、より好ましくは８２％～８５％である。本発明のゴム組成物はこのような物性を有するため、転がり抵抗を低減しながら、タイヤにした時の操縦安定性や耐久性を向上することができる。硬度が６５未満であると、タイヤにした時の操縦安定性が悪化する。反発弾性率が８０％未満であると、発熱が悪化し転がり抵抗を低減することができない。尚、これら硬度や反発弾性率は上述の配合のみで決定されるものではなく、例えば混練条件や混練方法によっても調整可能な物性である。
The hardness of the rubber composition for a tire of the present invention having such a composition is 65 or more, preferably 65 to 75, more preferably 65 to 70. The impact resilience at 40° C. of the rubber composition for a tire of the present invention is 80% or more, preferably 80% to 85%, more preferably 82% to 85%. Since the rubber composition of the present invention has such physical properties, it is possible to improve rolling stability and durability of the tire while reducing rolling resistance. When the hardness is less than 65, the steering stability when used as a tire is deteriorated. When the impact resilience is less than 80%, heat generation is deteriorated and the rolling resistance cannot be reduced. The hardness and the impact resilience are not determined only by the above-mentioned composition, but are physical properties that can be adjusted by the kneading conditions and the kneading method.
本発明のタイヤ用ゴム組成物は、上述の配合や物性により、転がり抵抗を低減しながら、タイヤにした時の操縦安定性や耐久性を向上することができる。具体的には、ゴム成分として天然ゴムに加えて末端変性ブタジエンゴムを併用し、且つ、充填材として粒径の大きいカーボンブラックを配合し、粒径の大きいカーボンブラックと末端変性ブタジエンゴムとを組み合わせて用いており、更に、ゴム組成物の硬度や反発弾性率を上記のように充分に高めているので、転がり抵抗を低減しながら、タイヤにした時の操縦安定性や耐久性を向上することができ、これら性能をバランスよく改善することができる。そのため、本発明のタイヤ用ゴム組成物は、空気入りタイヤのアンダートレッド部に用いることが好ましく、本発明のタイヤ用ゴム組成物をアンダートレッド部に用いた空気入りタイヤは、操縦安定性や耐久性を良好に維持しながら、燃費性能を向上することができる。
The rubber composition for a tire of the present invention can improve rolling stability and durability when being made into a tire while reducing rolling resistance due to the above-mentioned composition and physical properties. Specifically, in addition to natural rubber as a rubber component, end-modified butadiene rubber is used in combination, and carbon black having a large particle size is blended as a filler, and carbon black having a large particle size and terminal-modified butadiene rubber are combined. In addition, since the hardness and impact resilience of the rubber composition are sufficiently increased as described above, it is possible to improve the steering stability and durability of the tire while reducing rolling resistance. Therefore, these performances can be improved in a well-balanced manner. Therefore, the rubber composition for a tire of the present invention is preferably used in the undertread portion of a pneumatic tire, and the pneumatic tire using the rubber composition for a tire of the present invention in the undertread portion has steering stability and durability. Fuel economy performance can be improved while maintaining good performance.
以下、実施例によって本発明を更に説明するが、本発明の範囲はこれらの実施例に限定されるものではない。
The present invention will be further described below with reference to examples, but the scope of the present invention is not limited to these examples.
表１～２に示す配合からなる２４種類のゴム組成物（標準例１、比較例１～１２、実施例１～１１）を、それぞれ加硫促進剤および硫黄を除く配合成分を秤量し、１．８Ｌの密閉式バンバリーミキサーで５分間混練し、温度１５０℃でマスターバッチを放出し室温冷却した。その後、このマスターバッチを１．８Ｌの密閉式バンバリーミキサーに供し、加硫促進剤及び硫黄を加え２分間混合してゴム組成物を調製した。次に、得られたゴム組成物を所定の金型中で１６０℃、２０分間プレス加硫して加硫ゴム試験片を作製した。
Twenty-four types of rubber compositions having the formulations shown in Tables 1 and 2 (Standard Example 1, Comparative Examples 1 to 12 and Examples 1 to 11) were weighed for the compounding components except the vulcanization accelerator and sulfur, and 1 The mixture was kneaded for 5 minutes with an 8 L closed Banbury mixer, the master batch was discharged at a temperature of 150° C., and the mixture was cooled to room temperature. Then, this masterbatch was provided to a 1.8 L closed Banbury mixer, and a vulcanization accelerator and sulfur were added and mixed for 2 minutes to prepare a rubber composition. Next, the obtained rubber composition was press-vulcanized in a predetermined mold at 160° C. for 20 minutes to prepare a vulcanized rubber test piece.
尚、表１～２において、ゴム組成物の硬度は、ＪＩＳ Ｋ６２５３に準拠して、デュロメータのタイプＡにより温度２０℃で測定した。また、ゴム組成物の反発弾性率は、ＪＩＳ Ｋ６２５５に準拠して、リュプケ式反発弾性試験装置により温度４０℃で測定した。
In addition, in Tables 1 and 2, the hardness of the rubber composition was measured at a temperature of 20° C. by a durometer type A in accordance with JIS K6253. Further, the impact resilience of the rubber composition was measured at a temperature of 40° C. by a Lupke impact resilience tester in accordance with JIS K6255.
得られたゴム組成物について、下記に示す方法により、低燃費性能、操縦安定性、耐久性、耐クラック性、加工性の評価を行った。
The obtained rubber composition was evaluated for fuel efficiency, steering stability, durability, crack resistance, and workability by the methods shown below.
低燃費性能
得られたゴム組成物をアンダートレッドに使用した試験タイヤ（タイヤサイズ２１５／４５Ｒ１７）を作製し、標準リム（リムサイズ７ＪＪ）に組み付けて、空気圧を２３０ｋＰａとし、室内ドラム試験機（ドラム径：１７０７ｍｍ）を用いて、ＪＡＴＭＡ イヤーブック２００９年版記載の当該空気圧における最大負荷荷重の８５％に相当する荷重を負荷してドラムに押し付けた状態で、速度８０ｋｍ／ｈで走行させたときの転動抵抗を測定した。評価結果は、測定値の逆数を用いて、標準例１の値を１００とする指数で示した。この指数値が大きいほど転動抵抗が小さく、低燃費性能に優れることを意味する。 Low Fuel Consumption Performance A test tire (tire size 215/45R17) using the obtained rubber composition as an undertread was prepared and mounted on a standard rim (rim size 7JJ) to an air pressure of 230 kPa and an indoor drum tester (drum diameter). : 1707 mm) and rolling at a speed of 80 km/h while being pressed against the drum under a load equivalent to 85% of the maximum load under the air pressure described in JATMA Yearbook 2009 The resistance was measured. The evaluation result was shown by an index with the value of Standard Example 1 being 100, using the reciprocal of the measured value. The larger the index value, the smaller the rolling resistance and the better the fuel economy performance.
得られたゴム組成物をアンダートレッドに使用した試験タイヤ（タイヤサイズ２１５／４５Ｒ１７）を作製し、標準リム（リムサイズ７ＪＪ）に組み付けて、空気圧を２３０ｋＰａとし、室内ドラム試験機（ドラム径：１７０７ｍｍ）を用いて、ＪＡＴＭＡ イヤーブック２００９年版記載の当該空気圧における最大負荷荷重の８５％に相当する荷重を負荷してドラムに押し付けた状態で、速度８０ｋｍ／ｈで走行させたときの転動抵抗を測定した。評価結果は、測定値の逆数を用いて、標準例１の値を１００とする指数で示した。この指数値が大きいほど転動抵抗が小さく、低燃費性能に優れることを意味する。 Low Fuel Consumption Performance A test tire (tire size 215/45R17) using the obtained rubber composition as an undertread was prepared and mounted on a standard rim (rim size 7JJ) to an air pressure of 230 kPa and an indoor drum tester (drum diameter). : 1707 mm) and rolling at a speed of 80 km/h while being pressed against the drum under a load equivalent to 85% of the maximum load under the air pressure described in JATMA Yearbook 2009 The resistance was measured. The evaluation result was shown by an index with the value of Standard Example 1 being 100, using the reciprocal of the measured value. The larger the index value, the smaller the rolling resistance and the better the fuel economy performance.
操縦安定性
得られたゴム組成物をアンダートレッドに使用した試験タイヤ（タイヤサイズ２１５／４５Ｒ１７）を作製し、標準リム（リムサイズ７ＪＪ）に組み付けて、空気圧を２３０ｋＰａとし、排気量２０００ｃｃの試験車両に装着し、舗装路面からなるテストコースにて、８０ｋｍ／ｈ走行時にレーンチェンジをする際の路面応答性についてテストドライバーによる官能評価を行った。評価結果は、標準例１を１００とする指数値にて示した。この指数値が大きいほどレーンチェンジをする際の路面応答性が良好であり、操縦安定性が優れていることを意味する。 Steering stability A test tire (tire size 215/45R17) using the obtained rubber composition as an undertread was prepared and mounted on a standard rim (rim size 7JJ) to a test vehicle with an air pressure of 230 kPa and a displacement of 2000 cc. A test driver conducted a sensory evaluation on the road surface responsiveness when changing the lane at the time of running and traveling 80 km/h on a test course consisting of a paved road surface. The evaluation results are shown by index values with the standard example 1 being 100. The larger this index value, the better the road surface response at the time of lane change, and the better the steering stability.
得られたゴム組成物をアンダートレッドに使用した試験タイヤ（タイヤサイズ２１５／４５Ｒ１７）を作製し、標準リム（リムサイズ７ＪＪ）に組み付けて、空気圧を２３０ｋＰａとし、排気量２０００ｃｃの試験車両に装着し、舗装路面からなるテストコースにて、８０ｋｍ／ｈ走行時にレーンチェンジをする際の路面応答性についてテストドライバーによる官能評価を行った。評価結果は、標準例１を１００とする指数値にて示した。この指数値が大きいほどレーンチェンジをする際の路面応答性が良好であり、操縦安定性が優れていることを意味する。 Steering stability A test tire (tire size 215/45R17) using the obtained rubber composition as an undertread was prepared and mounted on a standard rim (rim size 7JJ) to a test vehicle with an air pressure of 230 kPa and a displacement of 2000 cc. A test driver conducted a sensory evaluation on the road surface responsiveness when changing the lane at the time of running and traveling 80 km/h on a test course consisting of a paved road surface. The evaluation results are shown by index values with the standard example 1 being 100. The larger this index value, the better the road surface response at the time of lane change, and the better the steering stability.
耐久性
得られたゴム組成物をアンダートレッドに使用した試験タイヤ（タイヤサイズ２１５／４５Ｒ１７）を作製し、標準リム（リムサイズ７ＪＪ）に組み付けて、空気圧を２３０ｋＰａとし、排気量２０００ｃｃの試験車両に装着し、８の字旋回テストコースを旋回加速度０．８Ｇ、５００ラップの条件で走行し、走行後のトレッド部の摩耗量を測定した。評価結果は、測定値の逆数を用い、標準例１を１００とする指数にて示した。この指数値が大きいほど摩耗量が小さく、耐久性に優れることを意味する。 Durability A test tire (tire size 215/45R17) in which the obtained rubber composition was used as an undertread was prepared, mounted on a standard rim (rim size 7JJ), the air pressure was set to 230 kPa, and mounted on a test vehicle of displacement 2000 cc. Then, the car was run on an 8-shaped turning test course under conditions of a turning acceleration of 0.8 G and 500 laps, and the amount of wear of the tread portion after running was measured. The evaluation results are shown by an index with the standard example 1 being 100, using the reciprocal of the measured value. The larger the index value, the smaller the amount of wear and the more excellent the durability.
得られたゴム組成物をアンダートレッドに使用した試験タイヤ（タイヤサイズ２１５／４５Ｒ１７）を作製し、標準リム（リムサイズ７ＪＪ）に組み付けて、空気圧を２３０ｋＰａとし、排気量２０００ｃｃの試験車両に装着し、８の字旋回テストコースを旋回加速度０．８Ｇ、５００ラップの条件で走行し、走行後のトレッド部の摩耗量を測定した。評価結果は、測定値の逆数を用い、標準例１を１００とする指数にて示した。この指数値が大きいほど摩耗量が小さく、耐久性に優れることを意味する。 Durability A test tire (tire size 215/45R17) in which the obtained rubber composition was used as an undertread was prepared, mounted on a standard rim (rim size 7JJ), the air pressure was set to 230 kPa, and mounted on a test vehicle of displacement 2000 cc. Then, the car was run on an 8-shaped turning test course under conditions of a turning acceleration of 0.8 G and 500 laps, and the amount of wear of the tread portion after running was measured. The evaluation results are shown by an index with the standard example 1 being 100, using the reciprocal of the measured value. The larger the index value, the smaller the amount of wear and the more excellent the durability.
耐クラック性
得られた試験片からＪＩＳ Ｋ６２５１に準拠したＪＩＳ３号ダンベル型試験片を切り出した。この試験片をＪＩＳ Ｋ６２６０に準拠し、デマチャ屈曲き裂試験機を用いて、温度２３℃、ストローク４０ｍｍ、速度３００±１０ｒｐｍ、屈曲回数１０万回の条件で、繰り返し屈曲によるき裂成長の長さを測定し、その後、試験片表面の亀裂（クラック）の有無を目視で観察し以下のＡ～Ｃで評価した。得られた結果を、表１～３の「耐クラック性」の欄に示した。
Ａ：亀裂の数が少ない（およそ１０個未満）
Ｂ：亀裂の数が多い（およそ１０個以上、１００個未満）
Ｃ：亀裂が無数に存在する（およそ１００個以上） Crack resistance A JIS No. 3 dumbbell type test piece according to JIS K6251 was cut out from the obtained test piece. The length of crack growth by repeated bending of this test piece was performed in accordance with JIS K6260 using a Demacha bending crack tester under the conditions of temperature 23° C., stroke 40 mm, speed 300±10 rpm, and bending number 100,000 times. Was measured, and then the presence or absence of cracks on the surface of the test piece was visually observed and evaluated by the following A to C. The obtained results are shown in the column of "crack resistance" in Tables 1 to 3.
A: Small number of cracks (less than about 10)
B: There are many cracks (about 10 or more and less than 100)
C: There are innumerable cracks (about 100 or more)
得られた試験片からＪＩＳ Ｋ６２５１に準拠したＪＩＳ３号ダンベル型試験片を切り出した。この試験片をＪＩＳ Ｋ６２６０に準拠し、デマチャ屈曲き裂試験機を用いて、温度２３℃、ストローク４０ｍｍ、速度３００±１０ｒｐｍ、屈曲回数１０万回の条件で、繰り返し屈曲によるき裂成長の長さを測定し、その後、試験片表面の亀裂（クラック）の有無を目視で観察し以下のＡ～Ｃで評価した。得られた結果を、表１～３の「耐クラック性」の欄に示した。
Ａ：亀裂の数が少ない（およそ１０個未満）
Ｂ：亀裂の数が多い（およそ１０個以上、１００個未満）
Ｃ：亀裂が無数に存在する（およそ１００個以上） Crack resistance A JIS No. 3 dumbbell type test piece according to JIS K6251 was cut out from the obtained test piece. The length of crack growth by repeated bending of this test piece was performed in accordance with JIS K6260 using a Demacha bending crack tester under the conditions of temperature 23° C., stroke 40 mm, speed 300±10 rpm, and bending number 100,000 times. Was measured, and then the presence or absence of cracks on the surface of the test piece was visually observed and evaluated by the following A to C. The obtained results are shown in the column of "crack resistance" in Tables 1 to 3.
A: Small number of cracks (less than about 10)
B: There are many cracks (about 10 or more and less than 100)
C: There are innumerable cracks (about 100 or more)
加工性
得られたゴム組成物をシート状に押出成形し、押出後３時間後の２枚の押出物（圧着用試料）を圧着荷重０．９８Ｎ、圧着時間０秒、圧着速度５０ｃｍ／ｍｉｎの条件で圧着した後に、剥離速度１２５ｃｍ／ｍｉｎの条件で剥離して、その際の粘着力をＰＩＣＭＡ式タックメーター（東洋精機製作所社製）により測定した。評価結果は、以下のＡ～Ｃで示した。尚、Ａ～Ｃの評価に用いた「タック指数」は、測定値を用いて、標準例１を１００とした指数である。
Ａ：加工性が非常に良好（タック指数が９５超）
Ｂ：加工性が良好（タック指数が８０超９５以下）
Ｃ：加工性が悪い（タック指数が８０以下） Processability The obtained rubber composition was extruded into a sheet, and two extrudates (sample for crimping) 3 hours after the extruding were subjected to a crimping load of 0.98 N, a crimping time of 0 seconds, and a crimping speed of 50 cm/min. After press-bonding under the conditions, the film was peeled under the condition of a peeling speed of 125 cm/min, and the adhesive force at that time was measured by a PICMA type tack meter (manufactured by Toyo Seiki Seisaku-sho, Ltd.). The evaluation results are shown in AC below. The "tack index" used for the evaluation of A to C is an index with the measured value as standard example 1 being 100.
A: Very good workability (Tack index over 95)
B: Good workability (tack index is more than 80 and 95 or less)
C: poor workability (tack index of 80 or less)
得られたゴム組成物をシート状に押出成形し、押出後３時間後の２枚の押出物（圧着用試料）を圧着荷重０．９８Ｎ、圧着時間０秒、圧着速度５０ｃｍ／ｍｉｎの条件で圧着した後に、剥離速度１２５ｃｍ／ｍｉｎの条件で剥離して、その際の粘着力をＰＩＣＭＡ式タックメーター（東洋精機製作所社製）により測定した。評価結果は、以下のＡ～Ｃで示した。尚、Ａ～Ｃの評価に用いた「タック指数」は、測定値を用いて、標準例１を１００とした指数である。
Ａ：加工性が非常に良好（タック指数が９５超）
Ｂ：加工性が良好（タック指数が８０超９５以下）
Ｃ：加工性が悪い（タック指数が８０以下） Processability The obtained rubber composition was extruded into a sheet, and two extrudates (sample for crimping) 3 hours after the extruding were subjected to a crimping load of 0.98 N, a crimping time of 0 seconds, and a crimping speed of 50 cm/min. After press-bonding under the conditions, the film was peeled under the condition of a peeling speed of 125 cm/min, and the adhesive force at that time was measured by a PICMA type tack meter (manufactured by Toyo Seiki Seisaku-sho, Ltd.). The evaluation results are shown in AC below. The "tack index" used for the evaluation of A to C is an index with the measured value as standard example 1 being 100.
A: Very good workability (Tack index over 95)
B: Good workability (tack index is more than 80 and 95 or less)
C: poor workability (tack index of 80 or less)
表１～２において使用した原材料の種類を下記に示す。
・ＮＲ：天然ゴム、ＴＳＲ２０（ガラス転移温度Ｔｇ：－６５℃）
・ＳＢＲ：スチレンブタジエンゴム、日本ゼオン社製 Ｎｉｐｏｌ １５０２（ガラス転移温度：－６０℃）
・変性Ｓ‐ＳＢＲ：末端変性溶液重合スチレンブタジエンゴム、日本ゼオン社製 Ｎｉｐｏｌ ＮＳ６１２（非油展品、ガラス転移温度Ｔｇ：－６５℃、官能基：水酸基）
・ＢＲ：ブタジエンゴム、日本ゼオン社製 Ｎｉｐｏｌ ＢＲ１２２０（ガラス転移温度Ｔｇ：－１０５℃）
・変性ＢＲ１：末端変性ブタジエンゴム、ＪＳＲ社製 ＢＲ５４（ガラス転移温度Ｔｇ：－１０７℃、官能基：シラノール基、分子量分布２．５）
・変性ＢＲ２：下記の方法で合成した末端変性ブタジエンゴム（ガラス転移温度Ｔｇ：－９３℃、官能基：ポリオルガノシロキサン基）
・変性ＢＲ３：末端変性ブタジエンゴム、日本ゼオン社製 Ｎｉｐｏｌ ＢＲ１２５０Ｈ（ガラス転移温度Ｔｇ：－９６℃、官能基：Ｎ‐メチルピロリドン基、分子量分布１．１）
・ＣＢ１：カーボンブラック、東海カーボン社製 シーストＫＨＰ（窒素吸着比表面積Ｎ2 ＳＡ：８５ｍ2 ／ｇ）
・ＣＢ２：カーボンブラック、新日化カーボン社製 ニテロン＃ＧＮ（窒素吸着比表面積Ｎ2 ＳＡ：３５ｍ2 ／ｇ）
・シリカ：デグサ社製 Ｕｌｔｒａｓｉｌ ＶＮ３（ＣＴＡＢ吸着比表面積：１５３ｍ2 ／ｇ）
・酸化亜鉛：正同化学工業社製 酸化亜鉛３種
・ステアリン酸：花王社製 ルナックＳ‐２５
・老化防止剤１：アミン系老化防止剤、フレキシス社製 サントフレックス６ＰＰＤ
・老化防止剤２：アミン‐ケトン系老化防止剤、大内新興化学工業社製 ノクラック２２４
・ワックス：大内新興化学工業社製 サンノック
・イオウ：四国化成工業社製 ミュークロンＯＴ‐２０
・加硫促進剤：大内新興化学工業社製 ノクセラーＣＺ The types of raw materials used in Tables 1 and 2 are shown below.
-NR: natural rubber, TSR20 (glass transition temperature Tg: -65°C)
SBR: styrene butadiene rubber, Nipol 1502 (glass transition temperature: -60°C) manufactured by Nippon Zeon Co., Ltd.
-Modified S-SBR: Terminal-modified solution-polymerized styrene-butadiene rubber, Nipol NS612 manufactured by Nippon Zeon Co., Ltd. (non-oil-extended product, glass transition temperature Tg: -65°C, functional group: hydroxyl group)
BR: butadiene rubber, Nipol BR1220 manufactured by Zeon Corporation (glass transition temperature Tg: -105°C)
-Modified BR1: end-modified butadiene rubber, JSR BR54 (glass transition temperature Tg: -107°C, functional group: silanol group, molecular weight distribution 2.5)
Modified BR2: terminal modified butadiene rubber synthesized by the following method (glass transition temperature Tg: -93°C, functional group: polyorganosiloxane group)
-Modified BR3: end-modified butadiene rubber, Nipol BR1250H manufactured by Nippon Zeon Co., Ltd. (glass transition temperature Tg: -96°C, functional group: N-methylpyrrolidone group, molecular weight distribution 1.1)
CB1: Carbon black, Tokai Carbon Co., Ltd., Seast KHP (nitrogen adsorption specific surface area N 2 SA: 85 m 2 /g)
CB2: carbon black, Niteron #GN (Nitrogen adsorption specific surface area N 2 SA: 35 m 2 /g) manufactured by Shin Nikka Carbon Co., Ltd.
Silica: Ultrasil VN3 (CTAB adsorption specific surface area: 153 m 2 /g) manufactured by Degussa
・Zinc oxide: Three types of zinc oxide manufactured by Shodo Chemical Industry・Stearic acid: Lunac S-25 manufactured by Kao
-Anti-aging agent 1: amine-based anti-aging agent, Santoflex 6PPD manufactured by Flexis
-Anti-aging agent 2: amine-ketone type anti-aging agent, Nocrac 224 manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
・Wax: Ouchi Shinko Chemical Co., Ltd. Sannok Sulfur: Shikoku Kasei Co., Ltd. Mucron OT-20
・Vulcanization accelerator: Nocceller CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
・ＮＲ：天然ゴム、ＴＳＲ２０（ガラス転移温度Ｔｇ：－６５℃）
・ＳＢＲ：スチレンブタジエンゴム、日本ゼオン社製 Ｎｉｐｏｌ １５０２（ガラス転移温度：－６０℃）
・変性Ｓ‐ＳＢＲ：末端変性溶液重合スチレンブタジエンゴム、日本ゼオン社製 Ｎｉｐｏｌ ＮＳ６１２（非油展品、ガラス転移温度Ｔｇ：－６５℃、官能基：水酸基）
・ＢＲ：ブタジエンゴム、日本ゼオン社製 Ｎｉｐｏｌ ＢＲ１２２０（ガラス転移温度Ｔｇ：－１０５℃）
・変性ＢＲ１：末端変性ブタジエンゴム、ＪＳＲ社製 ＢＲ５４（ガラス転移温度Ｔｇ：－１０７℃、官能基：シラノール基、分子量分布２．５）
・変性ＢＲ２：下記の方法で合成した末端変性ブタジエンゴム（ガラス転移温度Ｔｇ：－９３℃、官能基：ポリオルガノシロキサン基）
・変性ＢＲ３：末端変性ブタジエンゴム、日本ゼオン社製 Ｎｉｐｏｌ ＢＲ１２５０Ｈ（ガラス転移温度Ｔｇ：－９６℃、官能基：Ｎ‐メチルピロリドン基、分子量分布１．１）
・ＣＢ１：カーボンブラック、東海カーボン社製 シーストＫＨＰ（窒素吸着比表面積Ｎ2 ＳＡ：８５ｍ2 ／ｇ）
・ＣＢ２：カーボンブラック、新日化カーボン社製 ニテロン＃ＧＮ（窒素吸着比表面積Ｎ2 ＳＡ：３５ｍ2 ／ｇ）
・シリカ：デグサ社製 Ｕｌｔｒａｓｉｌ ＶＮ３（ＣＴＡＢ吸着比表面積：１５３ｍ2 ／ｇ）
・酸化亜鉛：正同化学工業社製 酸化亜鉛３種
・ステアリン酸：花王社製 ルナックＳ‐２５
・老化防止剤１：アミン系老化防止剤、フレキシス社製 サントフレックス６ＰＰＤ
・老化防止剤２：アミン‐ケトン系老化防止剤、大内新興化学工業社製 ノクラック２２４
・ワックス：大内新興化学工業社製 サンノック
・イオウ：四国化成工業社製 ミュークロンＯＴ‐２０
・加硫促進剤：大内新興化学工業社製 ノクセラーＣＺ The types of raw materials used in Tables 1 and 2 are shown below.
-NR: natural rubber, TSR20 (glass transition temperature Tg: -65°C)
SBR: styrene butadiene rubber, Nipol 1502 (glass transition temperature: -60°C) manufactured by Nippon Zeon Co., Ltd.
-Modified S-SBR: Terminal-modified solution-polymerized styrene-butadiene rubber, Nipol NS612 manufactured by Nippon Zeon Co., Ltd. (non-oil-extended product, glass transition temperature Tg: -65°C, functional group: hydroxyl group)
BR: butadiene rubber, Nipol BR1220 manufactured by Zeon Corporation (glass transition temperature Tg: -105°C)
-Modified BR1: end-modified butadiene rubber, JSR BR54 (glass transition temperature Tg: -107°C, functional group: silanol group, molecular weight distribution 2.5)
Modified BR2: terminal modified butadiene rubber synthesized by the following method (glass transition temperature Tg: -93°C, functional group: polyorganosiloxane group)
-Modified BR3: end-modified butadiene rubber, Nipol BR1250H manufactured by Nippon Zeon Co., Ltd. (glass transition temperature Tg: -96°C, functional group: N-methylpyrrolidone group, molecular weight distribution 1.1)
CB1: Carbon black, Tokai Carbon Co., Ltd., Seast KHP (nitrogen adsorption specific surface area N 2 SA: 85 m 2 /g)
CB2: carbon black, Niteron #GN (Nitrogen adsorption specific surface area N 2 SA: 35 m 2 /g) manufactured by Shin Nikka Carbon Co., Ltd.
Silica: Ultrasil VN3 (CTAB adsorption specific surface area: 153 m 2 /g) manufactured by Degussa
・Zinc oxide: Three types of zinc oxide manufactured by Shodo Chemical Industry・Stearic acid: Lunac S-25 manufactured by Kao
-Anti-aging agent 1: amine-based anti-aging agent, Santoflex 6PPD manufactured by Flexis
-Anti-aging agent 2: amine-ketone type anti-aging agent, Nocrac 224 manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
・Wax: Ouchi Shinko Chemical Co., Ltd. Sannok Sulfur: Shikoku Kasei Co., Ltd. Mucron OT-20
・Vulcanization accelerator: Nocceller CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
変性ＢＲ２の合成方法
攪拌機付きオートクレーブに、窒素雰囲気下、シクロヘキサン５６７０ｇ、１，３‐ブタジエン７００ｇおよび、テトラメチルエチレンジアミン０．１７ｍｍｏｌを仕込んだ後、シクロヘキサンと１，３‐ブタジエンとに含まれる重合を阻害する不純物の中和に必要な量のｎ‐ブチルリチウムを添加し、更に、重合反応に用いる分のｎ－ブチルリチウムを８．３３ｍｍｏｌ加えて、５０℃で重合を開始した。重合を開始してから２０分経過後に、１，３‐ブタジエン３００ｇを３０分間かけて連続的に添加した。重合反応中の最高温度は８０℃であった。連続添加終了後、更に１５分間重合反応を継続し、重合転化率が９５％から１００％の範囲になったことを確認してから、少量の重合溶液をサンプリングした。サンプリングした少量の重合溶液は、過剰のメタノールを添加して反応停止した後、風乾して、重合体を取得し、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）分析の試料とした。その試料を用いて、重合体（活性末端を有する共役ジエン系重合体鎖に該当）のピークトップ分子量および分子量分布を測定したところ、それぞれ、「２３万」および「１．０４」であった。 Method for synthesizing modified BR2 After charging cyclohexane 5670 g, 1,3-butadiene 700 g and tetramethylethylenediamine 0.17 mmol in a nitrogen atmosphere in an autoclave with a stirrer, the polymerization contained in cyclohexane and 1,3-butadiene is inhibited. The amount of n-butyllithium necessary for neutralizing the impurities was added, and further, 8.33 mmol of n-butyllithium for the polymerization reaction was added, and the polymerization was started at 50°C. After 20 minutes from the start of the polymerization, 300 g of 1,3-butadiene was continuously added over 30 minutes. The maximum temperature during the polymerization reaction was 80°C. After the continuous addition was completed, the polymerization reaction was continued for another 15 minutes, and after confirming that the polymerization conversion rate was in the range of 95% to 100%, a small amount of the polymerization solution was sampled. A small amount of the sampled polymerization solution was quenched by adding excess methanol and then air-dried to obtain a polymer, which was used as a sample for gel permeation chromatography (GPC) analysis. Using the sample, the peak top molecular weight and the molecular weight distribution of the polymer (corresponding to a conjugated diene-based polymer chain having an active end) were measured and found to be "230,000" and "1.04", respectively.
攪拌機付きオートクレーブに、窒素雰囲気下、シクロヘキサン５６７０ｇ、１，３‐ブタジエン７００ｇおよび、テトラメチルエチレンジアミン０．１７ｍｍｏｌを仕込んだ後、シクロヘキサンと１，３‐ブタジエンとに含まれる重合を阻害する不純物の中和に必要な量のｎ‐ブチルリチウムを添加し、更に、重合反応に用いる分のｎ－ブチルリチウムを８．３３ｍｍｏｌ加えて、５０℃で重合を開始した。重合を開始してから２０分経過後に、１，３‐ブタジエン３００ｇを３０分間かけて連続的に添加した。重合反応中の最高温度は８０℃であった。連続添加終了後、更に１５分間重合反応を継続し、重合転化率が９５％から１００％の範囲になったことを確認してから、少量の重合溶液をサンプリングした。サンプリングした少量の重合溶液は、過剰のメタノールを添加して反応停止した後、風乾して、重合体を取得し、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）分析の試料とした。その試料を用いて、重合体（活性末端を有する共役ジエン系重合体鎖に該当）のピークトップ分子量および分子量分布を測定したところ、それぞれ、「２３万」および「１．０４」であった。 Method for synthesizing modified BR2 After charging cyclohexane 5670 g, 1,3-butadiene 700 g and tetramethylethylenediamine 0.17 mmol in a nitrogen atmosphere in an autoclave with a stirrer, the polymerization contained in cyclohexane and 1,3-butadiene is inhibited. The amount of n-butyllithium necessary for neutralizing the impurities was added, and further, 8.33 mmol of n-butyllithium for the polymerization reaction was added, and the polymerization was started at 50°C. After 20 minutes from the start of the polymerization, 300 g of 1,3-butadiene was continuously added over 30 minutes. The maximum temperature during the polymerization reaction was 80°C. After the continuous addition was completed, the polymerization reaction was continued for another 15 minutes, and after confirming that the polymerization conversion rate was in the range of 95% to 100%, a small amount of the polymerization solution was sampled. A small amount of the sampled polymerization solution was quenched by adding excess methanol and then air-dried to obtain a polymer, which was used as a sample for gel permeation chromatography (GPC) analysis. Using the sample, the peak top molecular weight and the molecular weight distribution of the polymer (corresponding to a conjugated diene-based polymer chain having an active end) were measured and found to be "230,000" and "1.04", respectively.
前述の少量の重合溶液をサンプリングした直後、重合溶液に、１，６‐ビス（トリクロロシリル）ヘキサン０．２８８ｍｍｏｌ（重合に使用したｎ‐ブチルリチウムの０．０３４５倍モルに相当）を４０重量％シクロヘキサン溶液の状態で添加し、３０分間反応させた。更に、その後、ポリオルガノシロキサンＡ０．０３８２ｍｍｏｌ（重合に使用したｎ‐ブチルリチウムの０．００４５９倍モルに相当）を２０重量％キシレン溶液の状態で添加し、３０分間反応させた。その後、重合停止剤として、使用したｎ‐ブチルリチウムの２倍モルに相当する量のメタノールを添加した。これにより、変性ブタジエンゴムを含有する溶液を得た。この溶液に、ゴム成分１００部あたり、老化防止剤として２，４‐ビス（ｎ‐オクチルチオメチル）‐６‐メチルフェノール０．２部を添加した後、スチームストリッピングにより溶媒を除去し、６０℃で２４時間真空乾燥して、固形状の変性ブタジエンゴム（変性ＢＲ２）を得た。この変性ブタジエンゴム（変性ＢＲ２）について、重量平均分子量、分子量分布、カップリング率、ビニル結合含有量、および、ムーニー粘度を測定したところ、それぞれ、「５１万」、「１．４６」、「２８％」、「１１質量％」および「４６」であった。
Immediately after sampling a small amount of the above-mentioned polymerization solution, 40% by weight of 0.288 mmol of 1,6-bis(trichlorosilyl)hexane (corresponding to 0.0345 times mol of n-butyllithium used for the polymerization) was added to the polymerization solution. It was added in the state of a cyclohexane solution and reacted for 30 minutes. Further, after that, 0.0382 mmol of polyorganosiloxane A (corresponding to 0.00459 times mol of n-butyllithium used for the polymerization) was added in the state of a 20 wt% xylene solution and reacted for 30 minutes. Then, as a polymerization terminator, methanol was added in an amount corresponding to twice the mol of n-butyllithium used. As a result, a solution containing the modified butadiene rubber was obtained. To this solution, after adding 0.2 parts of 2,4-bis(n-octylthiomethyl)-6-methylphenol as an antioxidant per 100 parts of rubber component, the solvent was removed by steam stripping, It was vacuum dried at 24° C. for 24 hours to obtain a solid modified butadiene rubber (modified BR2). The weight average molecular weight, molecular weight distribution, coupling rate, vinyl bond content, and Mooney viscosity of this modified butadiene rubber (modified BR2) were measured to be "510,000", "1.46", and "28", respectively. %", "11 mass%" and "46".
表１～２から明らかなように、実施例１～１２のゴム組成物（タイヤ）は、標準例１に対して低燃費性能、操縦安定性、耐久性をバランスよく向上した。また、標準例１と同等以上の良好な耐クラック性および加工性を発揮した。
As is clear from Tables 1 and 2, the rubber compositions (tires) of Examples 1 to 12 improved the fuel economy performance, steering stability, and durability in a well-balanced manner compared to Standard Example 1. Further, good crack resistance and workability equivalent to or higher than those of Standard Example 1 were exhibited.
一方、比較例１のゴム組成物（タイヤ）は、末端変性ブタジエンゴムの代わりにスチレンブタジエンゴムが配合されているため、低燃費性能が悪化した。比較例２のゴム組成物（タイヤ）は、末端変性ブタジエンゴムの代わりに末端変性溶液重合スチレンブタジエンゴムが配合されているため、耐久性が悪化した。比較例３のゴム組成物（タイヤ）は、末端変性ブタジエンゴムの配合量が少なすぎるため、耐久性が悪化した。比較例４のゴム組成物（タイヤ）は、カーボンブラックの配合量が少なすぎるため、操縦安定性および耐久性が悪化した。比較例５のゴム組成物（タイヤ）は、カーボンブラックの窒素吸着比表面積が大きすぎるため、低燃費性能および耐久性が悪化した。比較例６のゴム組成物（タイヤ）は、天然ゴムおよび末端変性ブタジエンゴムだけでなく、更にスチレンブタジエンゴムが配合されているため、反発弾性が悪化した。比較例７のゴム組成物（タイヤ）は、硬度が小さすぎるため、操縦安定性が悪化した。比較例８のゴム組成物（タイヤ）は、反発弾性率が小さすぎるため、燃費性能が悪化した。比較例９のゴム組成物（タイヤ）は、末端変性ブタジエンゴムが配合されないため、低燃費性能、操縦安定性能を向上する効果が得られず、更に、アミン系ではない老化防止剤だけが配合されるので、耐クラック性および耐久性が悪化した。比較例１０のゴム組成物（タイヤ）は、末端変性ブタジエンゴムが配合されないため、低燃費性能、操縦安定性能、耐久性を向上する効果が得られず、更に、老化防止剤の配合量が多すぎるため、加工性が悪化した。比較例１１のゴム組成物（タイヤ）は、末端変性ブタジエンゴムが配合されないため、低燃費性能、操縦安定性能、耐久性を向上する効果が得られず、更に、ワックスの配合量が多すぎるため、加工性が悪化した。比較例１２のゴム組成物（タイヤ）は、末端変性ブタジエンゴムが配合されないため、低燃費性能、操縦安定性能、耐久性を向上する効果が得られず、更に、アミン系ではない老化防止剤だけが多量に配合されるため、耐クラック性および加工性が悪化した。
On the other hand, in the rubber composition (tire) of Comparative Example 1, the styrene-butadiene rubber was blended in place of the terminal-modified butadiene rubber, so the fuel economy performance deteriorated. In the rubber composition (tire) of Comparative Example 2, the terminal-modified solution-polymerized styrene-butadiene rubber was blended in place of the terminal-modified butadiene rubber, so the durability was deteriorated. The rubber composition (tire) of Comparative Example 3 was poor in durability because the compounding amount of the terminal-modified butadiene rubber was too small. In the rubber composition (tire) of Comparative Example 4, the steering stability and durability deteriorated because the amount of carbon black blended was too small. In the rubber composition (tire) of Comparative Example 5, since the nitrogen adsorption specific surface area of carbon black was too large, the fuel economy performance and the durability were deteriorated. The rubber composition (tire) of Comparative Example 6 contained not only natural rubber and terminal-modified butadiene rubber but also styrene-butadiene rubber, and thus the impact resilience deteriorated. The rubber composition (tire) of Comparative Example 7 had too low a hardness, and thus had poor steering stability. The rubber composition (tire) of Comparative Example 8 had a too small impact resilience, and thus the fuel efficiency was deteriorated. Since the rubber composition (tire) of Comparative Example 9 does not contain the terminal-modified butadiene rubber, it is not possible to obtain the effect of improving the fuel economy performance and the steering stability performance, and further, only the non-amine-based antioxidant is blended. Therefore, the crack resistance and durability deteriorated. In the rubber composition (tire) of Comparative Example 10, since the terminal-modified butadiene rubber was not blended, it was not possible to obtain the effect of improving the fuel economy performance, the steering stability performance, and the durability, and further, the antioxidant content was large. Since it was too much, workability deteriorated. In the rubber composition (tire) of Comparative Example 11, since the terminal-modified butadiene rubber was not blended, the effects of improving fuel economy performance, steering stability performance, and durability could not be obtained, and further, the amount of wax blended was too large. , Workability deteriorated. Since the rubber composition (tire) of Comparative Example 12 does not contain the terminal-modified butadiene rubber, it is not possible to obtain the effect of improving the fuel economy performance, the steering stability performance, and the durability. However, the crack resistance and workability deteriorated.
Claims (6)
- 天然ゴム５０質量％以上と末端変性ブタジエンゴム３５質量％～５０質量％とを含むゴム成分１００質量部に対して、窒素吸着比表面積Ｎ2 ＳＡが７０ｍ2 ／ｇ以下であるカーボンブラックが５０質量部以上配合されたタイヤ用ゴム組成物であって、硬度が６５以上、４０℃における反発弾性率が８０％以上であることを特徴とするタイヤ用ゴム組成物。 50 parts by mass of carbon black having a nitrogen adsorption specific surface area N 2 SA of 70 m 2 /g or less based on 100 parts by mass of a rubber component containing 50% by mass or more of natural rubber and 35% by mass to 50% by mass of terminal-modified butadiene rubber. A rubber composition for a tire, wherein the hardness is 65 or more and the impact resilience at 40° C. is 80% or more.
- 前記末端変性ブタジエンゴムの重量平均分子量（Ｍｗ）および数平均分子量（Ｍｎ）から求められる分子量分布（Ｍｗ／Ｍｎ）が２．０以下であることを特徴とする請求項１に記載のタイヤ用ゴム組成物。 The rubber for tires according to claim 1, wherein a molecular weight distribution (Mw/Mn) obtained from the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the terminal-modified butadiene rubber is 2.0 or less. Composition.
- 前記末端変性ブタジエンゴムの末端の官能基が水酸基、アミノ基、アミド基、アルコキシル基、エポキシ基、シロキサン結合基からなる群から選ばれる少なくとも１種であることを特徴とする請求項１または２に記載のタイヤ用ゴム組成物。 The terminal functional group of the terminal-modified butadiene rubber is at least one selected from the group consisting of a hydroxyl group, an amino group, an amide group, an alkoxyl group, an epoxy group, and a siloxane bonding group. The rubber composition for a tire as described.
- 前記ゴム成分１００質量部に対してアミン系老化防止剤が１．０質量部～４．０質量部配合されたことを特徴とする請求項１～３のいずれかに記載の空気入りタイヤ。 The pneumatic tire according to any one of claims 1 to 3, wherein an amine anti-aging agent is blended in an amount of 1.0 part by mass to 4.0 parts by mass with respect to 100 parts by mass of the rubber component.
- 前記ゴム成分１００質量部に対してワックスが０質量部超２．０質量部以下配合されたことを特徴とする請求項１～４のいずれかに記載の空気入りタイヤ。 The pneumatic tire according to any one of claims 1 to 4, wherein wax is blended with more than 0 parts by mass and 2.0 parts by mass or less based on 100 parts by mass of the rubber component.
- 請求項１～５のいずれかに記載のタイヤ用ゴム組成物をアンダートレッド部に用いたことを特徴とする空気入りタイヤ。 A pneumatic tire comprising the tire rubber composition according to any one of claims 1 to 5 in an undertread portion.
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| WO2009084285A1 (en) * | 2007-12-28 | 2009-07-09 | Sumitomo Rubber Industries, Ltd. | Rubber composition for tire |
| WO2010041737A1 (en) * | 2008-10-09 | 2010-04-15 | 株式会社ブリヂストン | Rubber compositions, manufacturing method therefor and tires using same |
| JP2011178848A (en) * | 2010-02-26 | 2011-09-15 | Sumitomo Rubber Ind Ltd | Rubber composition for tire and pneumatic tire |
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| WO2010041737A1 (en) * | 2008-10-09 | 2010-04-15 | 株式会社ブリヂストン | Rubber compositions, manufacturing method therefor and tires using same |
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| CN115181342B (en) * | 2022-08-22 | 2023-09-26 | 四川远星橡胶有限责任公司 | High-rebound-resilience high-modulus low-heat-generation tire lip protective adhesive and preparation method thereof |
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