JP2008115326A - Rubber composition and tire having tread using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition which reduces rolling resistance performance and can improve wet skid performance and steering stability and a tire having a tread using the same. <P>SOLUTION: The rubber composition comprises a rubber component and silica having secondary particles having a particle size distribution composed of a plurality of peaks, and in the particle size distribution of the silica, a peak intensity a in the peak particle diameter A on the side of the smallest particle diameter and a peak intensity b in the peak particle diameter B on the side of the largest particle diameter meet the relationship: 1<peak intensity b/peak intensity a<3.5. The tire has a tread using the composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  Conventionally, reduction in tire rolling resistance (improvement in rolling resistance performance) has led to a reduction in fuel consumption of vehicles. In recent years, there has been an increasing demand for lower fuel consumption of vehicles, and among the tire components, especially for rubber compositions for producing treads with a high occupation ratio in tires, superior low heat generation. Sex is required.

  As a technique for improving the low exothermic property of the rubber composition used for the tread, a method of reducing the blending amount of the reinforcing filler is known. However, in this case, the hardness of the rubber composition is lowered, so that the tire is softened, and there is a problem that the handling performance (steering stability) of the vehicle and the wet skid performance of the tire are lowered.

  As a technique for improving wet skid performance, a technique of blending anhydrous silica and hydrous silica (see, for example, Patent Document 1) is also known. However, there has been a problem that the rolling resistance cannot be sufficiently reduced and the demand for lower fuel consumption cannot be satisfied.

JP 2003-192842 A

  An object of the present invention is to provide a rubber composition capable of reducing rolling resistance performance and improving wet skid performance and steering stability, and a tire having a tread using the rubber composition.

The present invention contains a rubber component and silica having a particle size distribution in which secondary particles are composed of a plurality of peaks. In the particle size distribution of the silica, the peak intensity a at the peak particle size A on the smallest particle size side is the largest. A rubber composition in which the peak intensity b in the peak particle size B on the particle size side satisfies the following relational expression.
1 <peak intensity b / peak intensity a <3.5

  The peak particle size A on the smallest particle size side is preferably 0.1 to 5 μm.

  The peak particle size B on the largest particle size side is preferably 5 to 50 μm.

  The blending amount of the silica is preferably 30 to 150 parts by weight with respect to 100 parts by weight of rubber.

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

  According to the present invention, by containing a rubber component and predetermined silica, the rubber composition that can reduce rolling resistance performance and improve wet skid performance and driving stability, and a tread using the rubber composition are provided. Tires can be provided.

  The rubber composition of the present invention contains a rubber component and predetermined silica.

  As the rubber component, a diene rubber is preferable. Examples of the diene rubber include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR). And styrene isoprene butadiene rubber (SIBR). These rubber components may be used alone or in combination of two or more. Among these, SBR is preferable because the rolling resistance characteristics and the wet skid performance can be improved in a balanced manner.

  Examples of silica include silica (anhydrous silicic acid) obtained by a dry process and silica (hydrous silicic acid) obtained by a wet process, and there are many silanol groups on the surface, and the reaction point with a silane coupling agent. Silica obtained by a wet method is preferred because of its large amount.

  The rubber composition of this invention improves the dispersibility of a silica by containing the silica which has a particle size distribution from which a secondary particle consists of a some peak. Thereby, wet skid performance, low fuel consumption, and steering stability can be improved.

  In the particle size distribution of silica, the peak particle size A on the smallest particle size side is preferably 0.1 μm or more, and more preferably 0.2 μm or more. If the peak particle size A is less than 0.1 μm, the rolling resistance tends to increase. The peak particle size A is preferably 5 μm or less, and more preferably 4 μm or less. When the peak particle size A exceeds 5 μm, the dispersibility tends to deteriorate.

  In the particle size distribution of silica, the peak particle size B on the largest particle size side is preferably 5 μm or more, and more preferably 10 μm or more. When the peak particle size B is less than 5 μm, the dispersibility tends to deteriorate. The peak particle size B is preferably 50 μm or less, and more preferably 40 μm or less. When the peak particle size B exceeds 50 μm, the wet skid performance tends to deteriorate.

Furthermore, in the particle size distribution of silica, the peak intensity a at the peak particle diameter A and the peak intensity b at the peak particle diameter B satisfy the following relational expression.
1 <peak intensity b / peak intensity a <3.5

  Peak intensity b / peak intensity a (hereinafter referred to as peak intensity ratio) is greater than 1 and preferably greater than 1.5 from the viewpoint of dispersibility. The peak intensity ratio is less than 3.5, preferably less than 3.0. When the peak intensity ratio is 3.5 or more, steering stability is deteriorated.

  The particle size distribution of silica can be measured using a laser diffraction / scattering particle size distribution measuring apparatus.

  The compounding amount 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 compounding amount of silica is less than 30 parts by weight, not only the fracture strength is greatly reduced but also wet skid performance tends to be deteriorated. Further, the blending amount of silica is preferably 150 parts by weight or less, and more preferably 120 parts by weight or less. When the amount of silica exceeds 150 parts by weight, there is a tendency that rolling resistance cannot be sufficiently reduced.

  The rubber composition of the present invention preferably contains a silane coupling agent that is conventionally used in combination with silica.

  The silane coupling agent is not particularly limited. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) ) Tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide Sulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (2-trimethoxysilylethyl) trisulfide, Screw (4-trimethoxysilylbutyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxy Silylpropyl) 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 Sulfide systems such as 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, Mercapto type such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, vinyl type such as vinyltriethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3- (2-a Amino) amino-based aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyl Glycidoxy type such as dimethoxysilane, nitro type such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane And chloro-based compounds such as 2-chloroethyltriethoxysilane.

  The blending amount of the silane coupling agent is preferably 2 parts by weight or more, more preferably 5 parts by weight or more with respect to 100 parts by weight of silica. When the amount of the silane coupling agent is less than 2 parts by weight, the dispersibility of silica tends to deteriorate. The amount of the silane coupling agent is preferably 20 parts by weight or less, and more preferably 15 parts by weight or less. When the amount of the silane coupling agent exceeds 20 parts by weight, there is a tendency to bleed.

  In addition to the rubber component, silica, and silane coupling agent, the rubber composition of the present invention includes carbon black, clay and other replenishing fillers conventionally used in the production of rubber compositions, zinc oxide, and stearic acid. Various anti-aging agents, waxes, softeners, vulcanizing agents such as sulfur, various vulcanization accelerators, processing aids, and the like can be contained in amounts usually used as necessary.

  The rubber composition of the present invention is produced by a general method. That is, the rubber composition of the present invention is produced by kneading the rubber component and the predetermined silica with a Banbury mixer, kneader, open roll, etc., and if necessary, the silane coupling agent and the compounding agent, and then vulcanizing. can do.

  The rubber composition of the present invention is used for tires, and is suitably used as a tread among tire members because it can achieve both reduction in rolling resistance and improvement in wet skid performance.

  The tire of the present invention is produced by a usual method using the rubber composition of the present invention for a tread. That is, the rubber composition of the present invention is extruded in accordance with the shape of the tread at an unvulcanized stage and bonded to another tire member on a tire molding machine to form an unvulcanized tire. The tire of the present invention can be manufactured by heating and pressurizing the unvulcanized tire in a vulcanizer. As a method of forming the rubber composition of the present invention into a tread shape, a method of bonding a rubber composition into a predetermined shape, or inserting a rubber composition into two or more extruders And a method of forming two layers at the head outlet of the extruder.

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

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Styrene butadiene rubber (SBR): E60 manufactured by Asahi Kasei Chemicals Corporation
Silica (1): Ultrazil 7000GR manufactured by Degussa (number of secondary particle peaks: 2, peak particle size A: 0.4 μm, peak particle size B: 10 μm, peak intensity ratio (peak intensity b / peak intensity a ): 2.5)
Silica (2): Ultrazil VN3 manufactured by Degussa (number of secondary particle peaks: 2, peak particle size A: 0.4 μm, peak particle size B: 10 μm, peak intensity ratio (peak intensity b / peak intensity a ): 4.0)
Silane coupling agent: Si75 (bis (triethoxysilylpropyl) disulfide) manufactured by Degussa
Zinc oxide: Zinc oxide stearic acid manufactured by Mitsui Mining & Smelting Co., Ltd.
Anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Sulfur: Powder sulfur vulcanization accelerator made by Karuizawa Sulfur Co., Ltd. CZ: Noxeller CZ (N-cyclohexyl-2-benzothiazylsulfenamide) made by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator DPG: Nouchira D (N, N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

Examples 1 to 3 and Comparative Example 1
In accordance with the formulation shown in Table 1, chemicals other than sulfur and vulcanization accelerator were kneaded for 3 minutes at 150 ° C. using a Banbury mixer to obtain a kneaded product. Sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 3 minutes at 80 ° C. using a roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is formed into a tread shape, and bonded to another tire member on a tire molding machine to form an unvulcanized tire, and press vulcanized at 160 ° C. for 20 minutes. Thus, test tires (tire size: 195 / 65R15) of Examples 1 to 3 and Comparative Example 1 were manufactured.

(Rolling resistance)
Rolling resistance when the manufactured test tire was run at a speed (80 km / h) under the conditions of a rim (15 × 6JJ), internal pressure (230 kPa) and load (3.43 kN) using a rolling resistance tester. The rolling resistance index of Comparative Example 1 was taken as 100, and the rolling resistance of each formulation was displayed as an index according to the calculation formula shown below. In addition, it shows that rolling resistance can be reduced and it is so preferable that a rolling resistance index | exponent is large.
(Rolling resistance index) = (Rolling resistance of Comparative Example 1) / (Rolling resistance of each formulation) × 100

(Wet skid performance)
The manufactured test tire was mounted on all wheels of a test vehicle (domestic FF2000cc), and the brake was stepped on the wet asphalt road surface while traveling at an initial speed of 100 km / h to measure the braking distance. And the wet skid performance index | exponent of the comparative example 1 was set to 100, and the braking distance of each mixing | blending was displayed as an index | exponent with the calculation formula shown below. The larger the wet skid performance index, the better the wet skid performance.
(Wet skid performance index) = (braking distance of Comparative Example 1)
÷ (Brake distance for each formulation) x 100

(Maneuvering stability)
The manufactured test tires were attached to all the wheels of a test vehicle (domestic FF2000cc), and the test course was run on an actual vehicle, and the steering stability was evaluated by sensory evaluation of the driver. In the evaluation, the steering stability of Comparative Example 1 was set to 5 points, and a relative evaluation was performed with a maximum of 10 points. In addition, it shows that it is excellent in steering stability, so that the score of steering stability is large.

  The evaluation results are shown in Table 1.

Claims (5)

Containing a rubber component and silica having a particle size distribution in which secondary particles are composed of a plurality of peaks,
In the particle size distribution of the silica, a rubber composition in which the peak intensity a at the peak particle diameter A on the smallest particle diameter side and the peak intensity b at the peak particle diameter B on the largest particle diameter side satisfy the following relational expression.
1 <peak intensity b / peak intensity a <3.5 The rubber composition according to claim 1, wherein the peak particle size A on the smallest particle size side is 0.1 to 5 µm. The rubber composition according to claim 1 or 2, wherein the largest particle size B has a peak particle size B of 5 to 50 µm. The amount of silica is
The rubber composition according to claim 1, 2 or 3, which is 30 to 150 parts by weight with respect to 100 parts by weight of rubber. A tire having a tread using the rubber composition according to claim 1, 2, 3 or 4.