JP6900719B2 - Rubber composition for tread and tires - Google Patents

Description

The present invention relates to a rubber composition for tread and a tire having a tread composed of the rubber composition.

In order to prevent dust pollution caused by studded tires, the ban on the use of studded tires has been legislated, and studless tires have been used in place of studded tires in cold regions. When the tire is gripped on ice, water is generated on the ice surface, and in that case, the tire is in a state of floating on the water, so that sufficient grip force cannot be obtained, which causes slippage. Therefore, it is important to remove the water generated on the ice surface and bring the rubber surface of the tire into direct contact with the ice.

As a method of removing water on the ice surface, a method of using foam rubber and a method of allowing a balloon to exist inside the rubber are known, but in order to ensure the performance on ice, the content and occupied area of these are increased. I need to let you. However, when the content and the occupied area are increased, there is a problem that the durability and wear resistance of the studless tire are lowered.

Further, Patent Documents 1 and 2 also know a method of blending eggshell powder, crushed shells, and calcium carbonate with a rubber component to improve the performance on ice. As the amount is increased, there is a problem that the wear resistance is greatly deteriorated.

Methods to prevent deterioration of wear resistance include increasing the content ratio of natural rubber and using aroma oil instead of low-polarity oil such as mineral oil as oil, but performance on ice and snow deteriorates. .. There is also a method of using butadiene rubber having excellent wear resistance, but there is a concern that the cost will increase and the workability will deteriorate.

Furthermore, in recent years, due to the effects of global warming and the troublesome replacement of summer tires, studless tires are often used on roads other than ice and snow, and the wear resistance of the tread part of the studless tires has improved. More sought after.

JP-A-2007-169500 Japanese Unexamined Patent Publication No. 9-77915

An object of the present invention is to provide a rubber composition for a tread having excellent performance on low temperature ice and abrasion resistance, and a tire having a tread composed of the rubber composition.

The present invention is a rubber composition for a tread containing 3 to 15 parts by mass of eggshell powder having an average particle diameter of 120 μm or more and 10 parts by mass or less of at least one of a polyterpene resin and a terpene styrene resin with respect to 100 parts by mass of a rubber component. Regarding.

The present invention also relates to a tire having a tread composed of the rubber composition for tread.

A tire having a tread rubber composition containing the rubber component of the present invention, large particle eggshell powder, and at least one of a polyterpene resin and a terpene styrene resin and a tread composed of the tread rubber composition has low-temperature ice performance and resistance. Excellent wear resistance.

The rubber composition for tread of the present invention is characterized by containing a large particle eggshell powder having an average particle diameter of 120 μm or more and at least one of a polyterpene resin and a terpene styrene resin as a rubber component, and has low-temperature ice performance and abrasion resistance. Excellent for. Here, the eggshell powder having a large particle size exhibits a scratching effect due to the unevenness of the rubber surface remaining after the eggshell powder is detached, and is excellent in low-temperature ice performance, especially in starting performance at 0 ° C., while having abrasion resistance. Although it will decrease, the abrasion resistance can be improved by using at least one of the polyterpene resin and the terpene styrene resin in combination. This is because the rubber strength (elongation) is improved by containing at least one of the polyterpene resin and the terpene styrene resin, and the occurrence of unnecessary cracks and the like at the edge portion of the unevenness that appears when the eggshell falls off can be suppressed. It is considered that this is because the occurrence of wear is suppressed. Furthermore, it is expected that the performance on ice will be further improved because the uneven edges will be effective.

By containing eggshell powder, (A) the eggshell powder itself has the effect of scratching the ice and snow road surface, (B) the pores existing in the eggshell powder particles absorb and remove the water on the ice and snow road surface, and (C) the eggshell powder particles The pores formed by falling off absorb and remove water from the ice and snow road surface, and (D) the edge of the pores formed by the eggshell powder particles falling off acts as an edge and has the effect of scratching the ice and snow road surface. can get. In particular, the effect of (D) is more prominently exhibited by containing a large particle size eggshell powder.

The average particle size of the large-particle eggshell powder is 120 μm or more, preferably 125 μm or more, and more preferably 130 μm or more. When the average particle size of eggshell powder is less than 120 μm, the effect of improving the performance on low-temperature ice tends to be insufficient. The average particle size of eggshell powder is preferably 150 μm or less, more preferably 140 μm or less, and even more preferably 135 μm or less from the viewpoint of abrasion resistance. The average particle size of eggshell powder in the present specification is a value measured by a particle size distribution measuring device.

Examples of eggshell powder having an average particle size of 120 μm or more include eggshell powder calcium SQ-130 manufactured by Green Techno Co., Ltd.

The content of eggshell powder having an average particle size of 120 μm or more with respect to 100 parts by mass of the rubber component is 3 parts by mass or more, more preferably 5 parts by mass or more, because the effect of the present invention can be sufficiently obtained. The content of the eggshell powder is 15 parts by mass or less, more preferably 12 parts by mass or less, from the viewpoint of abrasion resistance.

Polyterpene resin and terpene styrene resin are used in rubber compositions for tires such as kumaron resin, petroleum resin (aliphatic petroleum resin, aromatic petroleum resin, alicyclic petroleum resin, etc.), phenolic resin, rosin derivative, etc. It is characterized by having a lower SP value than other adhesive resins used. Here, the SP value means a solubility parameter calculated by the Hoy method based on the structure of the compound, and the farther the SP values of the two compounds are, the lower the compatibility is. Here, since the SP value of water is about 23 and the SP value of the other adhesive resin is about 9 to 12, the polyterpene resin and the terpene styrene resin having lower SP values than the other adhesive resins are , It is an adhesive resin having a lower compatibility with water, and by using a rubber composition containing this, the water repellency of the rubber composition can be improved. The Hoy method is, for example, a calculation method described in K.L. Hoy “Table of Solubility Parameters”, Solvent and Coatings Materials Research and Development Department, Union Carbites Corp. (1985).

The polyterpene resin is a resin made from at least one selected from terpene compounds such as α-pinene, β-pinene, limonene, and dipentene. The terpene styrene resin is a resin made from the terpene raw material and styrene. The terpene styrene resin in the present specification refers to a resin in which the total amount of the terpene compound and styrene in the raw material is 80% by mass or more. The polyterpene resin and the terpene styrene resin may be hydrogenated resins (hydrogenated polyterpene resin, hydrogenated terpene styrene resin). The hydrogenation treatment to the terpene resin can be carried out by a known method, or a commercially available hydrogenated resin can also be used.

On the other hand, a terpene phenol resin made from a terpene compound and a phenol-based compound tends to deteriorate wear resistance, and therefore, it is preferable not to contain the terpene phenol resin.

The softening point of the polyterpene resin and the terpene styrene resin is preferably 75 ° C. or higher, more preferably 80 ° C. or higher, and even more preferably 90 ° C. or higher from the viewpoint of ease of handling. Further, from the viewpoint of workability and improvement of dispersibility between the rubber component and the filler, 150 ° C. or lower is preferable, 140 ° C. or lower is more preferable, and 130 ° C. or lower is further preferable. The softening point of the resin in the present invention is determined by using a flow tester (CFT-500D manufactured by Shimadzu Corporation, etc.) and using a plunger while heating 1 g of the resin as a sample at a heating rate of 6 ° C./min. A load of 1.96 MPa was applied, and the sample was extruded from a nozzle having a diameter of 1 mm and a length of 1 mm.

The glass transition temperature (Tg) of the polyterpene resin and the terpene styrene resin is preferably 80 ° C. or lower, more preferably 75 ° C. or lower, because it prevents the rubber composition from increasing the glass transition temperature and deteriorating the durability. .. The lower limit of the glass transition temperature of the terpene resin is not particularly limited, but is preferably 5 ° C. or higher because the weight average molecular weight (Mw) equal to or higher than that of oil can be obtained and the low volatility can be ensured. Further, the weight average molecular weight of the terpene resin is preferably 300 or less because it is excellent in volatility at high temperature and easily disappears.

The SP value of the polyterpene resin and the terpene styrene resin is preferably 8.90 or less, more preferably 8.80 or less, because the water repellency of the rubber composition can be further improved. The lower limit of the SP value of the terpene resin is preferably 7.5 or more from the viewpoint of compatibility with the rubber component.

The content of at least one of the polyterpene resin and the terpene styrene resin with respect to 100 parts by mass of the rubber component is 10 parts by mass or less, preferably 8 parts by mass or less from the viewpoint of abrasion resistance. Further, 2 parts by mass or more is preferable, and 4 parts by mass or more is more preferable, because the effect of the present invention can be obtained satisfactorily.

The rubber component is not particularly limited, and a rubber component used in a conventional tire tread rubber composition can be used. For example, isoprene-based rubber containing natural rubber and polyisoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR). Diene-based rubber components such as, and butyl-based rubber can be mentioned. These rubber components may be used alone or in combination of two or more. Among them, isoprene rubber, SBR, and BR are preferably contained from the viewpoint of balance of fuel efficiency, wear resistance, durability, and wet grip performance, and isoprene rubber and SBR are particularly excellent in chipping resistance. Is preferably contained.

Examples of the natural rubber include modified natural rubber such as natural rubber (NR), epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), and high-purity natural rubber (UPNR). Etc. are also included.

When the isoprene-based rubber is contained, the content in the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of being excellent in the kneading processability and extrusion processability of the rubber. Further, the content of the isoprene-based rubber is preferably 80% by mass or less, more preferably 70% by mass or less, from the viewpoint of being excellent in low temperature characteristics.

The BR includes a high cis BR having a cis content of 90% or more, a modified BR having a modified terminal and / or main chain, a modified BR (condensate, having a branched structure, etc.) coupled with a tin, silicon compound, or the like. Etc.) and so on. Among these BRs, Hisys BR is preferable because it has excellent wear resistance.

When BR is contained, the content in the rubber component is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more from the viewpoint of wear resistance. The BR content is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less from the viewpoint of processability.

In addition to the above components, the rubber composition of the present invention contains a compounding agent generally used for producing the rubber composition, for example, a filler other than the eggshell powder (other filler), zinc oxide, and stearic acid. , Softener, anti-aging agent, wax, vulcanizing agent, vulcanization accelerator and the like can be appropriately contained.

The other filler is not particularly limited, and examples thereof include eggshell powder (small particle eggshell powder) having an average particle diameter of less than 120 μm, carbon black, silica, aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, and talc. These fillers can be used alone or in combination of two or more.

The small particle eggshell powder is an eggshell powder having an average particle diameter of less than 120 μm, and is preferably 100 μm or less, more preferably 80 μm or less, still more preferably 30 μm or less, from the viewpoint of breaking strength. Further, the small particle eggshell powder is preferably 10 μm or more, more preferably 12 μm or more, because it is excellent in low-temperature ice performance.

When the small particle eggshell powder is contained, the content of the rubber component with respect to 100 parts by mass is preferably 1 part by mass or more, more preferably 3 parts by mass or more, because it is excellent in low-temperature ice performance. The content of the eggshell powder is preferably 20 parts by mass or less, more preferably 15 parts by mass or less.

Examples of carbon black include furnace black, acetylene black, thermal black, channel black, graphite, and the like, and these carbon blacks may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ ^{SA) of carbon black is preferably 70 m 2} / g or more, and more preferably 90 m ² / g or more, from the viewpoint of obtaining sufficient reinforcing properties and wear resistance. Also, N ₂ SA of carbon black is excellent in dispersibility, from the viewpoint that it is difficult to heat generation, preferably 300 meters ² / g or less, more preferably 250m ² / g. N ₂ SA can be measured according to JIS K 6217-2 "Carbon black for rubber-Basic characteristics-Part 2: How to obtain specific surface area-Nitrogen adsorption method-Single point method".

From the viewpoint of wear resistance, the DBP oil absorption amount of carbon black is preferably 50 ml / 100 g or more, and more preferably 100 ml / 100 g or more. From the viewpoint of grip performance, the DBP oil absorption amount of carbon black is preferably 250 ml / 100 g or less, more preferably 200 ml / 100 g or less, and more preferably 135 ml / 100 g or less. The DBP oil absorption amount of carbon black in the present specification is a value measured according to JIS K6217-4: 2008.

When carbon black is contained, the content of the diene rubber component with respect to 100 parts by mass is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more. If it is less than 5 parts by mass, sufficient reinforcing properties tend not to be obtained. The carbon black content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and even more preferably 60 parts by mass or less. If it exceeds 200 parts by mass, the workability tends to deteriorate, heat generation tends to occur easily, and wear resistance tends to decrease.

The silica is not particularly limited, and examples thereof include dry silica (silicic anhydride) and wet silica (hydrous silica), but wet silica is preferable because it contains a large amount of silanol groups.

The nitrogen adsorption specific surface area (N ₂ ^{SA) of silica is preferably 80 m 2} / g or more, and more preferably 100 m ² / g or more, from the viewpoint of durability and elongation at break. The N ₂ SA of the silica, from the viewpoint of fuel economy and workability, preferably 250 meters ² / g or less, more preferably 220 m ² / g. _{The N 2} SA of silica in the present specification is a value measured according to ASTM D3037-93.

When silica is contained, the content of the rubber component with respect to 100 parts by mass is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, from the viewpoint of durability and elongation at break. The silica content is 200 parts by mass from the viewpoint of improving dispersibility during kneading and from the viewpoint of suppressing the reaggregation of silica during heating during rolling and storage after rolling to reduce processability. The following is preferable, and 150 parts by mass or less is more preferable.

Silica is preferably used in combination with a silane coupling agent. As the silane coupling agent, any silane coupling agent conventionally used in combination with silica can be used in the rubber industry, for example, bis (3-triethoxysilylpropyl) disulfide and bis (3-triethoxy). Cyrilpropyl) Tetrasulfide and other sulfides, 3-mercaptopropyltrimethoxysilane, Momentive's NXT-Z100, NXT-Z45, NXT and other mercaptos (silane coupling agents having a mercapto group), vinyltriethoxysilane Vinyl type such as 3-aminopropyltriethoxysilane, amino type such as γ-glycidoxypropyltriethoxysilane, nitro type such as 3-nitropropyltrimethoxysilane, 3-chloropropyltrimethoxysilane Such as chloro system can be mentioned. These may be used alone or in combination of two or more.

When the silane coupling agent is contained, the content with respect to 100 parts by mass of silica is 4.0 parts by mass or more because an effect of improving sufficient filler dispersibility and an effect of reducing viscosity can be obtained. It is preferably 6.0 parts by mass or more, and more preferably 6.0 parts by mass or more. Further, the content of the silane coupling agent is preferably 12 parts by mass or less, preferably 10 parts by mass or less, because a sufficient coupling effect and silica dispersion effect cannot be obtained and the reinforcing property is lowered. Is more preferable.

Examples of the softener include low-temperature plasticizers, oils, and liquid diene-based polymers. Above all, it is preferable to contain an adhesive resin because the performance on ice is expected to be improved.

Examples of the low temperature plasticizer include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di2-ethylhexyl azelaate (DOZ), dibutyl sebacate (DBS), and diisononyl adipate. (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundesyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sevacinate (DOS), tributyl phosphate (TBP), trioctyl phosphate (DINA) Examples thereof include ester-based plasticizers such as TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricrecil phosphate (TCP), and trixylenyl phosphate (TXP), which are used at low temperatures. DOS and TOP are preferable from the viewpoint of the balance between the plasticizing effect and the abrasion resistance.

Examples of the oil include process oils such as paraffin-based, aroma-based, and naphthenic-based process oils.

The liquid diene polymer is a diene polymer in a liquid state at room temperature (25 ° C.), and is, for example, a liquid styrene-butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), or a liquid isoprene polymer. (Liquid IR), liquid styrene isoprene copolymer (liquid SIR) and the like can be mentioned. Of these, liquid SBR is preferable because it provides a good balance between wear resistance and stable grip performance during running.

The content of the rubber component with respect to 100 parts by mass when the softener is contained (the total amount of all when a plurality of softeners are used in combination) is 5 parts by mass or more because the effect of the present invention can be effectively obtained. Is preferable. Further, it is preferably 30 parts by mass or less.

The antiaging agent is not particularly limited, and those used in the rubber field can be used, and examples thereof include quinoline-based, quinone-based, phenol-based, and phenylenediamine-based antiaging agents.

When the anti-aging agent is contained, the content of the rubber component with respect to 100 parts by mass is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more. The content of the antiaging agent is preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, and 1.2 parts by mass from the viewpoints of dispersibility of the filler and the like, elongation at break, and kneading efficiency. Less than a part is more preferable.

The vulcanizing agent is not particularly limited, and those commonly used in the tire industry can be used. Sulfur is preferable, and powdered sulfur is more preferable, from the viewpoint that the effects of the present invention can be obtained satisfactorily. In addition, sulfur may be used in combination with other vulcanizing agents. Other vulcanizing agents include, for example, Tackylol V200 manufactured by Taoka Chemical Industry Co., Ltd., DURALINK HTS (1,6-hexamethylene-sodium dithiosulfate / dihydrate) manufactured by Flexis, and KA9188 manufactured by Rankses. Examples thereof include a vulcanizing agent containing a sulfur atom such as (1,6-bis (N, N'-dibenzylthiocarbamoyldithio) hexane) and an organic peroxide such as dicumyl peroxide.

When the vulcanizing agent is contained, the content of the rubber component with respect to 100 parts by mass is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more. The content of the vulcanizing agent is preferably 15 parts by mass or less, and more preferably 5 parts by mass or less.

Examples of the vulcanization accelerator include guanidine-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, thiuram-based, dithiocarbamate-based, and zandate-based compounds. Among them, a vulcanization accelerator having a benzothiazolyl sulfide group is preferable because the effect of the present invention can be preferably obtained.

Examples of the brewing accelerator having a benzothiazolyl sulfide group include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), and N. , N-Dicyclohexyl-2-benzothiazolyl sulfenamide (DCBS), N, N-diisopropyl-2-benzothiazolesulfenamide, N, N-di (2-ethylhexyl) -2-benzothiazolyl sulfenamide (BEHZ), N, N-di (2-methylhexyl) -2-benzothiazolyl sulfenamide (BMHZ), N-ethyl-N-t-butylbenzothiazole-2-sulfenamide (ETZ), etc. Examples thereof include sulfenamide-based sulfide accelerators, N-tert-butyl-2-benzothiazolyl sulfenimide (TBSI), and di-2-benzothiazolyl disulfide (DM).

When the vulcanization accelerator is contained, the content of the rubber component with respect to 100 parts by mass is preferably 0.5 parts by mass or more, and preferably 1.0 part by mass or more from the viewpoint of ensuring a sufficient vulcanization rate. The content of the vulcanization accelerator is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of suppressing blooming.

The rubber composition for tread of the present invention can be produced by a general method. For example, a known kneader used in the general rubber industry such as a Banbury mixer, a kneader, and an open roll is used to knead each of the above components other than the cross-linking agent and the vulcanization accelerator, and then knead the components. , A cross-linking agent and a vulcanization accelerator are added, the mixture is further kneaded, and then vulcanization is performed.

A tire using the rubber composition of the present invention can be produced by a usual method using the rubber composition. That is, the rubber composition obtained by blending the above-mentioned compounding agent with the diene-based rubber component as necessary is extruded according to the shape of the tread and bonded together with other tire members on a tire molding machine. An unvulcanized tire is formed by molding according to the above method, and the tire can be manufactured by heating and pressurizing the unvulcanized tire in a vulcanizer.

Although the present invention will be specifically described based on Examples, the present invention is not construed as being limited to these.

Various chemicals used in Examples and Comparative Examples will be described.
NR: TSR20
BR: BR150B manufactured by Ube Industries, Ltd. (Hisys BR, cis content 97% by mass)
Carbon Black: Dia Black I manufactured by Mitsubishi Chemical Corporation (ASTM No. N220, N ₂ SA: 114 m ² / g, DBP: 114 ml / 100 g, average particle size: 22 nm)
Eggshell powder 1: SQ-10 manufactured by Green Techno Co., Ltd. (average particle size: 10 μm)
Eggshell powder 2: SQ-50 manufactured by Green Techno Co., Ltd. (average particle size: 50 μm)
Eggshell powder 3: SQ-130 manufactured by Green Techno Co., Ltd. (average particle size: 130 μm)
Polyterpen resin: PX1150N manufactured by Yasuhara Chemical Co., Ltd. (Polyterpen resin without hydrogenation, SP value: 8.26, softening point: 115 ° C, Tg: 65 ° C)
Hydrogenated polyterpene resin: P125 manufactured by Yasuhara Chemical Co., Ltd. (hydrogenated polyterpene resin, hydrogenation rate: 100 mol%, SP value: 8.36, softening point: 125 ° C., Tg: 74 ° C.)
Terpene Styrene Resin: SYLVATARX6720 manufactured by Arizona Chemical (Non-hydrogenated Terpene Styrene Resin, SP Value: 8.70, Softening Point: 118 ° C, Tg: 70 ° C, Total of Terpene Compound and Styrene: 90% by Mass)
Terpene Phenol Formaldehyde: SYLVARES TP115 manufactured by Arizona Chemical
Oil: Process P-200 manufactured by Japan Energy Co., Ltd.
Wax: Sunknock N manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Stearic acid: Stearic acid "Camellia" manufactured by NOF CORPORATION
Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Metal Mining Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd .: Noxeller CZ (N-cyclohexyl-2-) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd. Benzothiazolyl vulcan amide)

Examples and Comparative Examples According to the formulation shown in Table 1, chemicals other than sulfur and vulcanization accelerator were kneaded for 5 minutes until the discharge temperature reached 170 ° C. using a 1.7 L sealed Banbury mixer, and kneaded. I got something. Further, the obtained kneaded product was kneaded again with the Banbury mixer at a discharge temperature of 150 ° C. for 4 minutes (remill). Next, using a twin-screw open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded for 4 minutes until the temperature reached 105 ° C. to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press-vulcanized at 170 ° C. for 12 minutes to prepare a test rubber composition.

Further, the unvulcanized rubber composition is extruded into a tire tread shape by an extruder equipped with a base having a predetermined shape, and bonded together with other tire members to form an unvulcanized tire, under the condition of 170 ° C. Test tires (size: 195 / 65R15, studless tires) were produced by press vulcanization underneath for 12 minutes.

The obtained unvulcanized rubber composition, vulcanized rubber composition and test tire were evaluated as follows. The evaluation results are shown in Table 1.

Low temperature ice performance (0 ° C start performance)
A vehicle equipped with test tires on the drive shaft was started from a state where it was stopped on the front road surface, and the mileage when the speed reached 10 km / h was measured. The results are indicated by an index, and the larger the index, the better the performance on low temperature ice. The index was calculated by the following formula. The performance target value is 118 or more.
(Low temperature figure of merit) = (mileage when reaching 10 km / h in Comparative Example 1) / (mileage when reaching 10 km / h in each formulation example) × 100

Abrasion resistance performance Each test tire was mounted on all wheels of a vehicle (domestic FF2000cc), and the groove depth of the tire tread after a mileage of 8000 km was measured to determine the mileage when the tire groove depth was reduced by 1 mm. .. The result is expressed by an index, and the larger the index, the better the wear resistance. The index was calculated by the following formula. The performance target value is 92 or more.
(Abrasion resistance performance index) = (mileage when the tire groove of each compounding example is reduced by 1 mm) / (mileage when the tire groove of Comparative Example 1 is reduced by 1 mm) × 100

From the results in Table 1, it was composed of a rubber composition for tread and the rubber composition containing at least one of a predetermined amount of eggshell powder having an average particle size of 120 μm or more, a polyterpene resin, and a terpene styrene resin with respect to the rubber component. It can be seen that the tire having a tread is excellent in low temperature ice performance and abrasion resistance.

Claims (2)

Relative to 100 parts by mass of the rubber component, the average 3 to 15 parts by mass particle size of more than eggshell powder 120 [mu] m, and polyterpene resins and terpene styrene rubber composition for a tread having 2-10 parts by weight containing at least one resin. A tire having a tread made of the rubber composition for tread according to claim 1.