JP2018119025A - Tread rubber composition and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tread rubber composition excellent in low temperature on-ice performance and wear resistance, and a tire having a tread composed of the tread rubber composition.SOLUTION: A tread rubber composition contains a rubber component, eggshell powder with an average particle size of 120 μm or more, and carbon black with an average particle size of 18 nm or less. There is also provided a tire having a tread composed of the tread rubber composition.SELECTED DRAWING: None

Description

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

  In order to prevent dust pollution caused by spiked tires, the prohibition of the use of spiked tires was legalized, and studless tires were used instead of spiked tires in cold regions. When the tire is gripped on the ice, water is generated on the ice surface. In this case, the tire floats on the water, so that a sufficient grip force cannot be obtained, which causes a slip. Therefore, it is important to remove the water generated on the ice surface so that the rubber surface of the tire is in direct contact with the ice.

  Known methods for removing water from the ice surface include the use of foamed rubber and the method of making a balloon exist inside the rubber. To ensure the performance on ice, the content and the area occupied by these materials are increased. It is necessary to let However, when the content or occupied area is increased, there is a problem that durability and wear resistance as a studless tire are lowered.

  Patent Documents 1 and 2 also disclose a method of improving the performance on ice by adding egg shell powder or shell shell pulverized product or calcium carbonate to the rubber component. 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-based oils instead of low-polar oils such as mineral oil as the oil, but the performance on ice and performance on snow deteriorate. . In addition, there is a method using a butadiene rubber excellent in wear resistance, but there is a concern that the cost increases or the workability deteriorates.

  Furthermore, in recent years, the impact of global warming and the replacement of summer tires has been troublesome, so for reasons such as crushing, there are many cases that run on studless tires other than icy and snowy roads. Abrasion is more demanded.

JP 2007-169500 A JP-A-9-77915

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

  The present invention relates to a rubber composition for a tread containing a rubber component, eggshell powder having an average particle diameter of 120 μm or more, and carbon black having an average particle diameter of 18 nm or less.

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

  A rubber composition for a tread containing a rubber component, a large particle eggshell powder and a carbon black having an average particle size of the present invention, and a tire having a tread composed of the rubber composition for a tread are provided with low-temperature on-ice performance and wear resistance. Excellent.

  The rubber composition for a tread of the present invention is characterized in that the rubber component contains a large particle eggshell powder having an average particle size of 120 μm or more and fine carbon black having a small average particle size, and has low temperature on-ice performance and wear resistance. Excellent. Here, the eggshell powder having a large particle diameter 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 on-ice performance, particularly at 0 ° C., while having wear resistance. Although it decreases, wear resistance can be improved by using the fine particle carbon black in combination. This is probably because fine carbon black gathers around the eggshell powder and a lot of fine carbon black is present in the part where the eggshell powder is detached, and the wear resistance can be prevented from lowering than expected.

  By containing eggshell powder (A) The effect of the eggshell powder itself scratching the snowy snow road surface, (B) The effect of the pores present in the eggshell powder particles absorbing and removing the water on the snowy snow road surface, (C) Eggshell powder The effect of the pores formed by the falling off of the powder particles absorbing and removing the water on the ice and snow road surface, and (D) the ridges of the pores formed by the dropping of the eggshell powder powder particles acting as edges, The effect of scratching is obtained. In particular, the effect of (D) is more remarkably exhibited by containing a large particle diameter eggshell powder.

  The average particle diameter 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 diameter of eggshell powder is less than 120 μm, the effect of improving the performance on ice at low temperatures tends to be insufficient. The average particle diameter of the eggshell powder is preferably 150 μm or less, more preferably 140 μm or less, and further preferably 135 μm or less from the viewpoint of wear resistance. In addition, the average particle diameter of eggshell powder in this specification is a value measured by a particle size distribution measuring device.

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

  The content of the eggshell powder having an average particle size of 120 μm or more with respect to 100 parts by mass of the rubber component is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, because the effects of the present invention are sufficiently obtained. Part or more is more preferable. Further, the content of the eggshell powder is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 12 parts by mass or less from the viewpoint of wear resistance.

  By containing the fine particle carbon black, it is possible to particularly improve the wear resistance of the rubber composition where the eggshell powder is detached.

  The average particle diameter of the fine carbon black is 18 nm or less, preferably 15 nm or less. When the average particle diameter of the fine carbon black exceeds 18 nm, the wear resistance may be reduced. The average particle size of carbon black is preferably 15 nm or more from the viewpoint of processability. In addition, the average particle diameter of carbon black in the present specification is a value measured by a transmission electron microscope.

  Examples of carbon black having an average particle size of 18 nm or less include Dia Black (average particle size: 19 nm) manufactured by Mitsubishi Chemical Corporation.

  The content of carbon black having an average particle size of 18 nm or less with respect to 100 parts by mass of the rubber component is preferably 10 parts by mass or more, more preferably 12 parts by mass or more, because the effect of the present invention is sufficiently obtained. Part or more is more preferable. Further, the content of the carbon black is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and further preferably 30 parts by mass or less from the viewpoint of workability.

  It does not specifically limit as a rubber component, The rubber component conventionally used for the rubber composition for treads of a tire can be used. For example, isoprene-based rubber including 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) And diene rubber components such as butyl rubber. These rubber components can be used alone or in combination of two or more. Among these, it is preferable to contain isoprene-based rubber, SBR, BR from the viewpoint of balance between fuel efficiency, wear resistance, durability, and wet grip performance, and isoprene-based rubber and SBR because it is particularly excellent in chipping resistance. It is preferable to contain.

  Examples of the natural rubber include natural rubber (NR), modified natural rubber such as 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, and more preferably 20% by mass or more from the viewpoint of excellent rubber kneading processability and extrusion processability. Further, the content of the isoprene-based rubber is preferably 80% by mass or less, and more preferably 70% by mass or less from the viewpoint of excellent low temperature characteristics.

  Examples of the BR include a high cis BR having a cis content of 90% or more, a modified BR having a terminal and / or main chain modified, a modified BR coupled with tin, a silicon compound, or the like (condensate having a branched structure) Etc.). Among these BRs, high cis BR is preferable because of its excellent wear resistance.

  In the case of containing BR, the content in the rubber component is preferably 1% by mass or more, more preferably 5% by mass or more, and further preferably 10% by mass or more from the viewpoint of wear resistance. Further, the BR content is preferably 80% by mass or less, more preferably 75% by mass or less, and further preferably 70% by mass or less from the viewpoint of workability.

  In addition to the above components, the rubber composition of the present invention is a compounding agent generally used in the production of rubber compositions, for example, fillers (other fillers) other than the eggshell powder and carbon black, zinc oxide , 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, eggshell powder having an average particle diameter of less than 120 μm (small particle eggshell powder), carbon black having an average particle diameter of more than 18 nm (other carbon black), silica, aluminum hydroxide, Alumina (aluminum oxide), calcium carbonate, talc and the like can be mentioned, and 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, preferably 100 μm or less, more preferably 80 μm or less, and even 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.

  The content with respect to 100 parts by mass of the rubber component in the case of containing small particle eggshell powder is preferably 1 part by mass or more, and more preferably 3 parts by mass or more, because it is excellent in low-temperature on-ice performance. Moreover, 20 mass parts or less are preferable and, as for content of the said eggshell powder, 15 mass parts or less are more preferable.

  The other carbon black is not particularly limited, and examples thereof include SAF, ISAF, HAF, FF, FEF, GPF, and SRF-LM that are generally used as a reinforcing filler in the tire industry.

  The content with respect to 100 parts by mass of the rubber component in the case of containing other carbon black is preferably 20 parts by mass or more, and more preferably 25 parts by mass or more, because sufficient reinforcing properties can be obtained. Further, the content of other carbon black is preferably 80 parts by mass or less, and more preferably 70 parts by mass or less, from the viewpoint of crack resistance (durability).

  The silica is not particularly limited, and examples thereof include dry process silica (anhydrous silicic acid), wet process silica (hydrous silicic acid), and the like, but wet process silica is preferable because of its large number of silanol groups.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 80 m ² / g or more, 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. Note that the N ₂ SA of the silica herein is a value measured in accordance with ASTM D3037-93.

  The content with respect to 100 parts by mass of the rubber component in the case of containing silica 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. Further, the content of silica is 200 parts by mass from the viewpoint of improving dispersibility at the time of kneading, and suppressing reduction of workability due to re-aggregation of silica during heating during rolling and storage after rolling. 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, bis (3-triethoxy Silylpropyl) sulfides such as tetrasulfide, 3-mercaptopropyltrimethoxysilane, NXT-Z100, NXT-Z45, NXT, etc. manufactured by Momentive (a silane coupling agent having a mercapto group), vinyltriethoxysilane Vinyl such as 3-aminopropyl triethoxysilane, glycidoxy such as γ-glycidoxypropyltriethoxysilane, nitro such as 3-nitropropyltrimethoxysilane, 3-chloropropyltrimethoxysilane Down like chloro systems such. These may be used alone or in combination of two or more.

  The content with respect to 100 parts by mass of silica in the case of containing a silane coupling agent is 4.0 parts by mass or more because the effect of improving the filler dispersibility and the effect of reducing the viscosity can be obtained. Preferably, it is 6.0 parts by mass or more. In addition, the content of the silane coupling agent is preferably 12 parts by mass or less, and is preferably 10 parts by mass or less because sufficient coupling effect and silica dispersion effect cannot be obtained and the reinforcing property is lowered. It is more preferable.

  Examples of the softener include an adhesive resin, a low temperature plasticizer, an oil, and a liquid diene polymer. Among them, it is preferable to contain an adhesive resin because the performance on ice is expected to be improved.

  Examples of the adhesive resin include resins conventionally used in rubber compositions for tires such as aromatic petroleum resins. Examples of aromatic petroleum resins include phenolic resins, coumarone indene resins, terpene resins, styrene resins, acrylic resins, rosin resins, dicyclopentadiene resins (DCPD resins), and the like. Examples of the phenolic resin include colesin (manufactured by BASF) and tackolol (manufactured by Taoka Chemical Industry Co., Ltd.). Examples of the coumarone indene resin include Escron (manufactured by Nippon Steel Chemical Co., Ltd.), neopolymer (manufactured by JX Nippon Mining & Energy Corporation), and the like. Examples of the styrene resin include Sylvatrax 4401 (manufactured by Arizona chemical). Examples of the terpene resin include TR7125 (manufactured by Arizona chemical) and TO125 (manufactured by Yasuhara Chemical Co., Ltd.). These adhesive resins may be used alone or in combination of two or more. Among these, phenolic resins, coumarone indene resins, terpene resins, and acrylic resins are preferably used because of excellent grip performance during traveling, and terpene resins are particularly preferable because of excellent performance on ice.

  Examples of the low-temperature plasticizer include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate ( TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), ester plasticizers such as trixylenyl phosphate (TXP), and the like at low temperatures Plastic effect and wear resistant balun From, DOS, TOP is preferable.

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

  The liquid diene polymer is a diene polymer in a liquid state at room temperature (25 ° C.), 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. Among these, liquid SBR is preferable because it provides a good balance between wear resistance and stable grip performance during traveling.

  The content with respect to 100 parts by mass of the rubber component in the case of containing the softening agent (the total amount when all of the softening agents are used in combination) is 5 parts by mass or more because the effects of the present invention can be effectively obtained. Is preferred. Moreover, 30 mass parts or less are preferable.

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

  When the anti-aging agent is contained, the content relative to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, and more preferably 0.8 parts by mass or more. The content of the anti-aging 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 fillers, elongation at break, and kneading efficiency. Part or less is more preferable.

  The vulcanizing agent is not particularly limited, and those commonly used in the tire industry can be used. From the point that the effect of the present invention can be obtained satisfactorily, sulfur is preferable, and powdered sulfur is more preferable. Sulfur may be used in combination with other vulcanizing agents. Other vulcanizing agents include, for example, Tachiroll V200 manufactured by Taoka Chemical Co., Ltd., DURALINK HTS (1,6-hexamethylene-sodium dithiosulfate dihydrate) manufactured by Flexis, and KA9188 manufactured by LANXESS. Examples thereof include vulcanizing agents containing sulfur atoms such as (1,6-bis (N, N′-dibenzylthiocarbamoyldithio) hexane) and organic peroxides such as dicumyl peroxide.

  When the vulcanizing agent is contained, the content with respect to 100 parts by mass of the rubber component is preferably 0.1 parts by mass or more, and more preferably 0.5 parts by mass or more. Moreover, 15 mass parts or less are preferable, and, as for content of a vulcanizing agent, 5 mass parts or less are more preferable.

  Examples of the vulcanization accelerator include guanidine, aldehyde-amine, aldehyde-ammonia, thiazole, sulfenamide, thiourea, thiuram, dithiocarbamate, and zanddate compounds. Among these, a vulcanization accelerator having a benzothiazolyl sulfide group is preferable because the effects of the present invention can be suitably obtained.

  Examples of the vulcanization accelerator having a benzothiazolyl sulfide group include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N , N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), N, N-diisopropyl-2-benzothiazolesulfenamide, N, N-di (2-ethylhexyl) -2-benzothiazolylsulfenamide (BEHZ), N, N-di (2-methylhexyl) -2-benzothiazolylsulfenamide (BMHZ), N-ethyl-Nt-butylbenzothiazole-2-sulfenamide (ETZ), etc. Sulfenamide vulcanization accelerators and N-tert-butyl-2-benzothiazolylsulfen De (TBSI), di-2-benzothiazolyl disulfide (DM), and the like.

  In the case of containing a vulcanization accelerator, the content with respect to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more and more preferably 1.0 part by mass or more from the viewpoint of securing a sufficient vulcanization rate. Further, 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 a tread of the present invention can be produced by a general method. For example, in a known kneader used in a general rubber industry such as a Banbury mixer, a kneader, and an open roll, after kneading components other than the crosslinking agent and the vulcanization accelerator among the above components, Further, it can be produced by a method of adding a crosslinking agent and a vulcanization accelerator, kneading and then vulcanizing.

  A tire using the rubber composition of the present invention can be produced by an ordinary method using the rubber composition. That is, the rubber composition in which the above compounding agent is blended as necessary with respect to the diene rubber component is extruded according to the shape of the tread, and is bonded together with other tire members on a tire molding machine. By molding by this method, an unvulcanized tire is formed, and the unvulcanized tire can be heated and pressurized in a vulcanizer to produce a tire.

  The present invention will be specifically described based on examples, but the present invention is not construed as being limited to these examples.

Various chemicals used in Examples and Comparative Examples will be described.
NR: TSR20
BR: BR1220 (Non-modified BR, cis content: 96% by mass) manufactured by Nippon Zeon Co., Ltd.
Carbon Black: Dia Black I (ASTM No. N220, N ₂ SA: 114 m ² / g, DBP: 114 ml / 100 g, average particle size: 22 nm) manufactured by Mitsubishi Chemical Corporation
Silica: Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA: 175 m ² / g, average primary particle size: 15 nm)
Silane coupling agent: Si75 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa
Fine particle carbon black: Dia Black (average particle size: 19 nm) manufactured by Mitsubishi Chemical Corporation
Eggshell powder 1: SQ-130 (average particle size: 130 μm) manufactured by Green Techno
Eggshell powder 2: SQ-50 (average particle size: 50 μm) manufactured by Green Techno
Eggshell powder 3: SQ-10 (average particle size: 10 μm) manufactured by Green Techno
Terpene resin: PX1150N (polyterpene resin) manufactured by Yashara Chemical Co., Ltd.
Wet resin: SYLVATRAXX4401 manufactured by Arizona Chemical
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Oil: Process X-140 (Aroma Oil) manufactured by Japan Energy Co., Ltd.
Stearic acid: Stearic acid “椿” manufactured by NOF Corporation
Zinc oxide: Zinc Hana No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd .: Noxeller CZ (N-cyclohexyl-2-) manufactured by Ouchi Shinsei Chemical Benzothiazolylsulfenamide)

Examples and Comparative Examples In accordance with the formulation shown in Table 1, using a 1.7 L closed Banbury mixer, kneaded chemicals other than sulfur and vulcanization accelerator for 5 minutes until the discharge temperature reached 170 ° C. I got a thing. Further, the obtained kneaded material was kneaded again (remill) with the Banbury mixer at a discharge temperature of 150 ° C. for 4 minutes. Next, using a biaxial open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded material, and kneaded for 4 minutes until reaching 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 predetermined-shaped die, and is bonded together with other tire members to form an unvulcanized tire. A test tire (size: 195 / 65R15, studless tire) was produced by press vulcanization for 12 minutes.

  The following evaluation was performed about the obtained unvulcanized rubber composition, the vulcanized rubber composition, and the test tire. The evaluation results are shown in Table 1.

Low temperature ice performance (0 ° C start performance)
A vehicle equipped with a test tire on the drive shaft was started from a state where it stopped on the surface of the road surface, and the travel distance when the vehicle 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.
(Low-temperature performance index on ice) = (traveling distance reaching 10 km / h in Comparative Example 1) / (traveling distance reaching 10 km / h in each blending example) × 100

Abrasion resistance performance Each test tire was mounted on all wheels of a vehicle (domestic FF2000cc), the groove depth of the tire tread portion after a mileage of 8000 km was measured, and the mileage when the tire groove depth was reduced by 1 mm was obtained. . The results are expressed as an index, and the larger the index, the better the wear resistance. The index was calculated by the following formula.
(Abrasion resistance performance index) = (travel distance when the tire groove of each blending example is reduced by 1 mm) / (travel distance when the tire groove of Comparative Example 1 is reduced by 1 mm) × 100

  From the results in Table 1, a rubber component, a tread rubber composition containing an egg shell powder having an average particle diameter of 120 μm or more, and carbon black having an average particle diameter of 18 nm or less, and a tire having a tread composed of the rubber composition are It can be seen that the low-temperature performance on ice and the wear resistance are excellent.

Claims (2)

A rubber composition for a tread comprising a rubber component, eggshell powder having an average particle size of 120 μm or more, and carbon black having an average particle size of 18 nm or less. A tire having a tread composed of the rubber composition for a tread according to claim 1.