JP5079252B2 - Rubber composition for tread and tire having tread using the same - Google Patents

Description

  The present invention relates to a rubber composition for a tread and a tire having a tread using the same.

  The tread of the tire is a rubber layer in a portion where the tire is in contact with the ground, and a so-called grip for gripping the road surface between the tire and the ground is secured. The blending of the rubber composition used for the tread layer is an important factor governing the wet skid performance, wear resistance and low heat buildup of the tire.

  Further, in recent years, there has been an increasing demand for a vehicle with a low fuel consumption specification, and accordingly, a higher level of performance is also desired for the tires constituting the vehicle. In particular, a rubber composition having a low rolling resistance is desired for a rubber composition used for a tread layer having a large volume in the entire tire. Rolling resistance is mainly classified into three types, that is, air resistance, friction resistance, and resistance due to hysteresis loss of tire constituent members, and among these, rolling resistance due to hysteresis loss of tire constituent members occupies the largest weight. The hysteresis loss of the tire constituent member is a work amount consumed for the rubber, and corresponds to a work amount accumulated as heat inside. That is, the better the low heat generation, the smaller the amount of work consumed with respect to the rubber, leading to a reduction in rolling resistance and a reduction in fuel consumption.

  As a method for improving the low heat build-up, a method for reducing the content of the filler as a reinforcing agent is known, but when this method is used, the hardness of the rubber is lowered, so that the handling stability is lowered. To do. Furthermore, the wet skid performance is also reduced. In order to improve the wet skid performance, it is necessary to increase the rolling resistance. However, when the rolling resistance is reduced to reduce fuel consumption as described above, the wet skid performance is degraded. After all, there is a problem that it is difficult to improve all of steering stability, wet skid performance and low heat build-up.

  Patent Document 1 discloses a rubber composition that contains ethylene propylene diene rubber (EPDM) and zinc oxide in a predetermined amount, has no blooming of the compounding agent, has a relatively low hardness, and has excellent wear resistance. Yes. However, this rubber composition is used for a roll of a paper feed mechanism such as an OA apparatus, and is not considered for application to a tire. Even if this rubber composition is applied to a tire, the hardness is extremely high. Therefore, there is still room for improvement due to lack of steering stability and wet skid performance.

JP-A-11-349177

  An object of the present invention is to provide a rubber composition for a tread having improved rolling resistance characteristics, wet skid performance, wear resistance performance and steering stability performance, and a tire having a tread using the same.

  The present invention relates to a rubber composition for a tread containing 1 to 15 parts by weight of a halogenated phenol resin with respect to 100 parts by weight of a rubber component.

  The rubber composition for tread preferably contains 30 to 150 parts by weight of silica.

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

  According to the present invention, a rubber composition for a tread having improved rolling resistance characteristics, wet skid performance, wear resistance performance and steering stability performance by containing a predetermined amount of a rubber component and a halogenated phenol resin, and the use thereof It is possible to provide a tire having a tread.

  The rubber composition of the present invention contains a rubber component and a halogenated phenol resin.

  Examples of the rubber component include natural rubber (NR), isoprene rubber (IR), styrene butadiene rubber (SBR), butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), Halogenated butyl rubber (X-IIR), styrene isoprene butadiene copolymer rubber (SIBR), halides of copolymers of isomonoolefin and paraalkyl styrene, and the like. These rubber components can be used alone. Alternatively, two or more kinds may be used in combination. Among these, NR, IR, SBR, and BR are preferable, and SBR is more preferable because grip performance, low fuel consumption, and wear resistance are improved. In addition, since it is inferior to mechanical strength, it is preferable not to contain EPDM.

  As SBR, there are emulsion polymerization SBR (E-SBR) and solution polymerization SBR (S-SBR), but the degree of freedom of styrene and vinyl is high, and it is easy to design so as to sufficiently improve performance such as grip performance. For reasons, S-SBR is preferred.

  As S-SBR, it is preferable to use a high molecular weight material coupled with Sn or Si. The coupling method of S-SBR is, for example, by reacting an alkali metal (such as Li) or alkaline earth metal (such as Mg) at the molecular chain end of S-SBR with, for example, tin halide or silicon halide. Can be obtained.

  The content of SBR in the rubber component is preferably 20% by weight or more, and more preferably 30% by weight or more. If the SBR content is less than 20% by weight, the grip performance tends not to be improved.

  The halogenated phenol resin is obtained by halogenating a phenol resin obtained by reacting phenols such as phenol, cresol, xylenol, and resorcin with aldehydes such as formaldehyde, acetaldehyde, and furfural with an acid or an alkali catalyst.

  Examples of the halogen atom of the halogenated phenol resin include chlorine, fluorine, bromine and iodine. Among these, chlorine and / or bromine are preferable and bromine is more preferable because of high reactivity and cost reduction.

  The method for halogenating the phenol resin is not particularly limited, and examples thereof include a method for obtaining a halogenated phenol resin by reacting an aldehyde unit in the phenol resin with a hydrogen halide.

  The degree of polymerization (n) of the halogenated phenol resin is preferably 1 or more, and more preferably 3 or more. Further, n of the halogenated phenol resin is preferably 10 or less, and more preferably 6 or less. When n of the halogenated phenol resin exceeds 10, there is a tendency that the reactive groups decrease and the rolling resistance increases.

  Content of halogenated phenol resin is 1 weight part or more with respect to 100 weight part of rubber components, Preferably it is 2 weight part or more. When the content of the halogenated phenol resin is less than 1 part by weight, a sufficient improvement effect of grip performance cannot be obtained. The content of the halogenated phenol resin is 15 parts by weight or less, preferably 10 parts by weight or less. If the content of the halogenated phenol resin exceeds 15 parts by weight, the rubber composition is excessively cured and the elastomeric property is lowered, so that the wet skid performance cannot be improved.

  According to the present invention, by containing a predetermined amount of a rubber component and a halogenated phenol resin, a rubber composition for a tread having reduced rolling resistance and excellent grip performance can be obtained.

  The rubber composition for a tread of the present invention preferably contains silica.

  There is no restriction | limiting in particular as a silica, Although what was prepared by the wet method or the dry method can be used, It is preferable to use especially the silica prepared by the wet method.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably not less than 20 m ² / g, more preferably at least 30 m ² / g, more 40 m ² / g is more preferred. When N ₂ SA of silica is less than 20 m ² / g, the wear resistance tends to deteriorate. Further, the silica of the N ₂ SA is preferably 400 meters ² / g or less, more preferably 250 meters ² / g, more preferably 200 meters ² / g or less. If N ₂ SA of silica exceeds 400 m ² / g, it tends to be difficult to disperse in rubber.

  The content of silica is preferably 30 parts by weight or more and more preferably 45 parts by weight or more with respect to 100 parts by weight of the rubber component. When the content of silica is less than 30 parts by weight, there is a tendency that a sufficient improvement effect of reinforcing properties cannot be obtained. The silica content is preferably 150 parts by weight or less, more preferably 120 parts by weight or less. When the silica content exceeds 150 parts by weight, the silica is not uniformly dispersed in the rubber and the processability of the rubber tends to deteriorate.

  When silica is contained, it is preferable to use a silane coupling agent together with silica.

  Examples of the silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, and bis (3-triethoxy). Methoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (2-triethoxysilyl) Ethyl) trisulfide, bis (4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (2-trimethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) Trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2 -Trimethoxysilylethyl) disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl Tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilyl pro Sulfide series such as rubenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane , 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane and other mercapto-based, vinyltriethoxysilane, vinyltrimethoxysilane and other vinyl-based, 3-aminopropyltriethoxysilane 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethyl Glycidoxy series such as amino series such as xysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane Nitro compounds such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltri Examples include chloro-based compounds such as ethoxysilane, and these can be used alone or in any combination.

  The content of the silane coupling agent is preferably 2 parts by weight or more and more preferably 3 parts by weight or more with respect to 100 parts by weight of silica. When the content of the silane coupling agent is less than 2 parts by weight, there is a tendency that rubber and silica cannot be sufficiently bonded. Further, the content of the silane coupling agent is preferably 15 parts by weight or less, and more preferably 12 parts by weight or less. When the content of the silane coupling agent exceeds 15 parts by weight, vulcanization inhibition tends to be caused.

  In addition to the rubber component, halogenated phenol resin, silica, and silane coupling agent, the tread rubber composition of the present invention includes compounding agents conventionally used in the rubber industry, such as fillers other than silica, oils, etc. Softeners, zinc oxide, stearic acid, various anti-aging agents, vulcanizing agents such as wax and sulfur, various vulcanization accelerators and the like can be appropriately blended as necessary.

  After vulcanization, the JIS-A hardness of the rubber composition for a tread of the present invention is preferably 50 or more, and more preferably 55 or more. When the rubber composition for treads of the present invention has a JIS-A hardness of less than 55, the wear resistance tends to deteriorate. Further, after vulcanization, the JIS-A hardness of the rubber composition for a tread of the present invention is preferably 90 or less, more preferably 80 or less. When the JIS-A hardness of the rubber composition for a tread of the present invention exceeds 90, the grip performance tends to be inferior.

  The tire of the present invention is produced by an ordinary method using the rubber composition for a tread of the present invention for a tire tread. That is, the rubber composition is extruded into the shape of a tread portion of a tire at an unvulcanized stage, and bonded together by a normal method on a tire molding machine to form an unvulcanized tire. The unvulcanized tire can be heated and pressurized in a vulcanizer to obtain a tire.

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

Next, various chemicals used in Examples and Comparative Examples will be described together.
SBR: SBR E15 manufactured by Asahi Kasei Corporation (S-SBR coupled with an epoxy group, styrene bond amount: 23% by weight, vinyl bond amount: 64% by weight)
Silica: Ultrazil VN3 manufactured by Degussa (N ₂ SA: 170 m ² / g)
Silane coupling agent: Si75 (bis (triethoxysilylpropyl) disulfide) manufactured by Degussa
Aroma oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Zinc oxide: Stearic acid manufactured by Mitsui Mining & Smelting Co., Ltd .: Anti-aging agent manufactured by Nippon Oil & Fats Co., Ltd .: Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl manufactured by Sumitomo Chemical Co., Ltd.) -P-phenylenediamine))
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Sulfur: Powdered sulfur halogenated phenolic resin manufactured by Karuizawa Sulfur Co., Ltd .: Tacrol 250-III manufactured by Taoka Chemical Industry Co., Ltd. (alkylphenol-formaldehyde resin, carbon number of alkyl group of alkylphenol: 5, polymerization degree: 4, halogen :bromine)
Vulcanization accelerator (1): Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator (2): Noxeller D (1,3-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

Examples 1-2 and Comparative Examples 1-3
According to the formulation shown in Table 1, various chemicals excluding sulfur and a vulcanization accelerator were kneaded with a Banbury mixer at 150 ° C. for 5 minutes to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded with a biaxial open roll at 80 ° C. for 5 minutes to prepare an unvulcanized rubber sheet. Furthermore, the obtained unvulcanized rubber sheet was vulcanized at 160 ° C. for 20 minutes to produce a vulcanized rubber sheet.

(hardness)
The hardness of the vulcanized rubber sheet was measured at 25 ° C. using a spring type A according to the test method of “Hardness test method of vulcanized rubber and thermoplastic rubber” of JIS K 6253.

(Rolling resistance)
The obtained unvulcanized rubber sheet is molded into a tread shape and bonded to another tire member with a tire molding machine to form an unvulcanized tire, and the unvulcanized tire is vulcanized at 160 ° C. for 20 minutes. Thus, test tires (tire size: 195 / 65R15) of Examples 1-2 and Comparative Examples 1-3 were manufactured. Furthermore, using a rolling resistance tester, the rolling resistance when the test tire was run under the conditions of rim: 15 × 6JJ, internal pressure: 230 kPa, load: 3.43 kN, speed: 80 km / h was compared, and the comparison was made. The rolling resistance index of Example 1 was set to 100, and the rolling resistance of each formulation was indicated by an index according to the following formula. In addition, it shows that rolling resistance index is so small that rolling resistance is small and it is excellent in low-fuel-consumption property.
(Rolling resistance index) = (Rolling resistance of Comparative Example 1)
÷ (Rolling resistance of each compound) x 100

(Wet skid performance)
All the test tires (domestic FF2000cc) were mounted on the test tire, the braking distance from 100 km / h on the wet asphalt road surface was calculated, the wet skid performance index of Comparative Example 1 was set to 100, and the following formula The wet skid performance of each formulation was displayed as an index. The larger the wet skid performance index, the shorter the stop distance and the better the wet skid performance.
(Wet skid performance index) = (braking distance of Comparative Example 1)
÷ (braking distance for each formulation) x 100

(Abrasion resistance)
By running a test course of 10 km per lap at 80 km / h with a vehicle equipped with the tire, the amount of decrease in the groove depth of the tread after running 30000 km was measured, and the wear resistance performance index of Comparative Example 1 was set to 100, The wear resistance index of each formulation was calculated by the following formula. In addition, it shows that it is excellent in abrasion resistance, so that an abrasion resistance index is large.
(Abrasion resistance index) = (Reduction in groove depth of Comparative Example 1)
÷ (reduction in groove depth for each formulation) x 100

(Maneuvering stability)
The test tire was mounted on a car on a dry asphalt road test course, and the vehicle was driven. The test driver sensorially evaluated the stability of control during steering. In addition, evaluation was a 10-point perfect score, and the comparative example 1 was made into 6 points and relative evaluation was carried out. The larger the value, the better the steering stability.

  The evaluation results of the above test are shown in Table 1.

Claims (3)

For 100 parts by weight of the rubber component consisting only of styrene butadiene rubber ,
1 to 15 parts by weight of a halogenated phenol resin ,
Containing 45 to 120 parts by weight of silica having a nitrogen adsorption specific surface area of 40 to 200 m ² / g,
A rubber composition for a tread containing 3 to 12 parts by weight of a silane coupling agent with respect to 100 parts by weight of silica . The rubber composition for a tread according to claim 1, wherein the silane coupling agent is bis (triethoxysilylpropyl) disulfide. A tire having a tread using the rubber composition for a tread according to claim 1.