JP2002080642A - Rubber composition for tread, and tire obtained using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire tread and a tire considerably improved in grip performances on a wet road surface, abrasion resistant performances and heat build-up resistant performances while maintaining grip performances on a dry road surface. SOLUTION: The rubber composition for a tire tread comprises (A) a natural rubber and/or a dienic rubber, (B) polyacrylate particles, polymethyl methacrylate particles, or crosslinked particles thereof, each having an average particle size of 1-200 μm and (C) a reinforcing filler, where the content of the particles (B) is 1-20 pts.wt. and the total content of the particles (B) and the reinforcing filler (C) is 30-200 pts.wt., each based on 100 pts.wt. of the rubber (A).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for a tire tread and a tire using the same, and more particularly to a grip performance on a wet road surface (wet grip) while maintaining a grip performance on a dry road surface (dry grip performance). The present invention relates to a rubber composition for a tire tread that can provide a tire having improved performance), abrasion resistance and heat generation resistance, and a tire using the composition for a tread.

[0002]

2. Description of the Related Art With the recent demand for energy savings in society, the characteristics required for tires are becoming severer year by year. For the purpose of saving fuel consumption of automobiles, reduction of heat generation of rubber for tires is one of them. Can be In general, in order to reduce heat generation, that is, to reduce rolling resistance, it is conceivable to reduce the filling amount of carbon black or use carbon black having a large particle size.In either case, not only does wet grip performance deteriorate, but also reinforcement is required. It is also known that the wear and abrasion performance are also reduced.

On the other hand, hydrous silicic acid is known as a filler satisfying both low heat generation (heat generation performance), wet grip performance, reinforcement and wear resistance. However, this has a lower storage elastic modulus of the rubber composition as compared with carbon black having a similar specific surface area, and therefore has poor dry grip performance. As a method of increasing the storage elastic modulus, an increase in the amount of hydrous silicic acid or an increase in the specific surface area can be considered, but this leads to a decrease in heat generation resistance.

Various proposals have been made in the past to solve these problems, but a rubber composition having a high balance of dry grip performance, wet grip performance, abrasion resistance and heat generation resistance has not yet existed. is the current situation.

[0005]

SUMMARY OF THE INVENTION The present invention provides a rubber composition for a tire tread which improves wet grip performance, abrasion resistance and heat generation resistance without deteriorating dry grip performance under such circumstances. It is to provide a tire using the composition for a tread.

[0006]

Means for Solving the Problems As a result of intensive research and development for solving the above-mentioned problems, a part of the reinforcing filler was partially converted into polyacrylate particles or polymethyl methacrylate particles having an average particle diameter of 1 to 200 μm. And by replacing them with the respective crosslinked particles, in addition to the network structure by the reinforcing filler such as carbon black or silica particles, polyacrylate particles having an average particle diameter of 1 to 200 μm, polymethyl methacrylate particles or crosslinked particles thereof Improves the grip performance (grounding property) and abrasion resistance in order to relieve stress by dispersing locally applied strain, and also has polyacrylic acid ester particles, polymethyl methacrylate particles having an average particle diameter of 1 to 200 μm or The heat generation performance is greatly improved due to the elastic characteristics of each crosslinked particle itself. Heading was.

That is, the present invention provides (A) a natural rubber and / or a diene rubber, and (B) an average particle diameter of 1 to 200 μm.
m of polyacrylic acid ester particles, polymethyl methacrylate particles or their respective crosslinked particles, and (C) a reinforcing filler, and the content of particles (B) is 1 to 100 parts by weight of rubber (A). ~ 20 parts by weight, particles (B)
And a reinforcing filler (C) in a total content of 30 to 200 parts by weight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the rubber composition for a tire tread of the present invention, (A) natural rubber and / or diene-based synthetic rubber is used. Here, as the diene rubber,
For example, styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene synthetic rubber (IR), acrylonitrile-butadiene rubber (NBR), isobutylene-isoprene rubber (IIR), chloroprene rubber (CR) and the like can be mentioned. The rubber (A) may be used alone or in combination of two or more.

As the (B) polyacrylate particles, polymethyl methacrylate particles or crosslinked particles thereof, various particles are used. In the present invention, the particles (B) may be used alone or in combination of two or more.

The average particle diameter of the particles (B) is 1 to 200 μm.
m, preferably 1 to 100 μm. If the average particle diameter of the particles (B) is less than 1 μm, the aggregation of the reinforcing filler such as carbon black cannot be affected, so that the hysteresis loss cannot be reduced and the heat generation resistance decreases. On the other hand, if it exceeds 200 μm, the cohesion of the reinforcing filler is broken, so that the interaction is reduced and the wear resistance is reduced.

The content of the particles (B) is 10%.
It is 1 to 20 parts by weight, preferably 1 to 15 parts by weight per 0 parts by weight. If the content of the particles (B) is less than 1 part by weight, the grip performance and the heat generation resistance are insufficiently improved.
If the amount exceeds 0 parts by weight, the wear resistance and the heat generation resistance decrease.

The reinforcing filler (C) can be arbitrarily selected from those conventionally used in rubber compositions for tire treads, and carbon black and silica particles are preferably used. The carbon black preferably has a nitrogen adsorption specific surface area of 80 to 280 m ² / g, and the silica preferably has a nitrogen adsorption specific surface area of 100 to 280 m ² / g. If the nitrogen adsorption specific surface area of the carbon black is less than 80 m ² / g, the abrasion resistance tends to decrease, and if it exceeds 280 m ² / g, the heat generation resistance tends to decrease. If the nitrogen adsorption specific surface area of the silica is less than 100 m ² / g, the abrasion resistance tends to decrease, and if it exceeds 280 m ² / g, the heat generation resistance tends to decrease.

The reinforcing filler (C) has the general formula
(1): nM · xSiO_y・ ZH_TwoO (1) (where M is aluminum (Al), calcium (C
a) from magnesium (Mg) and titanium (Ti)
At least one metal element or oxide selected from the group consisting of
Or a hydroxide, n is 1 to 5, x is 0 to 10, y
Represents a numerical value in the range of 2 to 5, and z represents a numerical value in the range of 0 to 10. )
Those containing inorganic compound particles to be used are also preferably used.
It is. When x and z are both 0 in the general formula (1),
Those corresponding to the formula (1) are Al, Ca, Mg and Ti
At least one metal or oxide selected from the group consisting of
Or it becomes hydroxide. Here, represented by the general formula (1)
Examples of inorganic compounds include aluminum hydroxide (Al)
(OH)_Three), Alumina (Al_TwoO_Three, Al_TwoO_Three・ 3H_TwoO
(Hydrate)), clay (Al_TwoO_Three・ 2SiO_Two), Khao
Phosphorus (Al_TwoO_Three・ 2SiO_Two・ 2H_TwoO), pyrophylla
(Al_TwoO_Three・ 4SiO_Two・ H_TwoO), bentonite
(Al_TwoO_Three・ 4SiO_Two・ 2H_TwoO), aluminum silicate
(Al_TwoSiO_Five, Al_Four(SiO_Two)_Three・ 5H_TwoO
Etc.), aluminum calcium silicate (Al_TwoO_Three・ Ca
O.2SiO_Two), Calcium hydroxide (Ca (O
H)_Two), Calcium oxide (CaO), calcium silicate
(Ca_TwoSiO_Four), Magnesium calcium silicate
(CaMgSiO_Four), Magnesium hydroxide (Mg (O
H)_Two), Magnesium oxide (MgO), talc (Mg
O ・ 4SiO_Two・ H_TwoO), Attapulgite (5MgO
・ 8SiO_Two・ 9H_TwoO), aluminum magnesium oxide
(MgO ・ Al_TwoO_Three), Titanium white (TiO_Two), Chita
Black (Ti_nO _2n-1). n is close to 1
It is a numerical value. Among these, aluminum hydroxide and aluminum hydroxide
Lumina is particularly preferably used. The inorganic compound particles
Preferably has a center particle diameter of 0.01 to 10 μm.
No. If the center particle diameter is less than 0.01 μm, the grip performance
When the thickness exceeds 10 μm, the abrasion resistance becomes poor.
Tends to decrease. The central particle size is the maximum of individual particles
It is the average value of the particle diameter. In the present invention, a reinforcing filler
(C) may be used alone or in combination of two or more.
You may.

The compounding amount of the reinforcing filler (C) can be 5 to 200 parts by weight, more preferably 50 to 100 parts by weight, per 100 parts by weight of the rubber (A). If the amount of the reinforcing filler (C) is less than 5 parts by weight, the abrasion resistance tends to decrease, and if it exceeds 200 parts by weight, the heat generation resistance tends to decrease.

In the rubber composition for a tire tread of the present invention, the total content of the particles (B) and the reinforcing filler (C) is 30 to 200 parts by weight based on 100 parts by weight of the rubber (A).
Preferably it is 50 to 100 parts by weight. By using the particles (B) and the reinforcing filler (C) at such a ratio, the network structure of the reinforcing filler (C) is added, and the polyacrylate having an average particle diameter of the particles (B) of 1 to 200 μm is used. Particles, polymethyl methacrylate particles or their respective cross-linked particles disperse locally applied strain to relieve stress, improve grounding and rigidity, improve wet grip performance and wear resistance, and further improve polyacrylic Due to the elastic characteristics of the acid ester particles, polymethyl methacrylate particles, or the respective crosslinked particles themselves, the heat generation resistance is greatly improved, and low rolling resistance can be achieved.

The mixing ratio of the particles (B) to the reinforcing filler (C) is, for example, from 1: 2 to 1: 100 by weight.
Preferably it can be set to 1:10 to 1:50.

In the rubber composition of the present invention, in addition to the above-mentioned components, various chemicals usually used in the rubber industry, for example, vulcanizing agents such as sulfur, various vulcanization accelerators, various softening agents, Additives such as various antioxidants, zinc oxide, stearic acid, antioxidants, and antiozonants can be blended. The tire of the present invention is produced by a usual method using the rubber composition for a tire tread of the present invention. That is, if necessary, the rubber composition of the present invention containing the above-mentioned various chemicals is extruded into a tread member in an unvulcanized stage, and is formed by sticking it on a tire molding machine by an ordinary method. Form a sulfur tire. The unvulcanized tire is heated and pressed in a vulcanizer to obtain a tire. The tire of the present invention thus obtained has an excellent balance of dry grip performance, wet grip performance, abrasion resistance, low heat generation (heat resistance), and the like.

[0018]

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

Hereinafter, the reagents used in Examples and Comparative Examples will be summarized. Natural rubber: RSS3 manufactured by Techbee Hang SBR: SBR1502 manufactured by JSR Corporation Silica: Ultrasil VN3 (Ultras manufactured by Degussa)
il VN3) (nitrogen adsorption specific surface area: 210 m ² / g) Carbon black: Showa Cabot Co. Ltd. SHOWBLACK N220 (nitrogen adsorption specific surface area: 125m ² /
g) Clay: Suplex manufactured by JM Huber (central particle size: 0.3 μm, B
ET specific surface area: 22 to 26 m ² / g, DBP oil absorption: 3
5 to 40 g / 100 g, pH: 4.5 to 5.5) Crosslinked polyacrylate particles: Techpolymer ARX-15 manufactured by Sekisui Plastics Co., Ltd. (average particle diameter: 1)
5 μm) Crosslinked polymethyl methacrylate particles: Techpolymer MB20X-5 manufactured by Sekisui Plastics Co., Ltd. (average particle size:
5 μm) Polymethyl methacrylate particles: MP manufactured by Soken Chemical Co., Ltd.
-1451 (average particle diameter: 0.15 µm) Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa Aroma oil: JOMO process X140 manufactured by Japan Energy Co., Ltd. Antioxidant : Nocrack 6 manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
C (N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine) Stearic acid: Stearic acid manufactured by NOF CORPORATION Zinc oxide: Zinc flower No. 1 manufactured by Mitsui Kinzoku Mining Co., Ltd. Sulfur: powder sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator: Noxeller C manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Z

Examples 1 to 4 and Comparative Examples 1 to 6 According to the contents of Table 1, kneading and compounding were carried out to obtain rubber compositions. These rubber compositions were press-vulcanized at 170 ° C. for 20 minutes to obtain vulcanized rubbers, which were evaluated for the following properties.

(Wet grip performance) The wet grip performance was measured using a British Standard portable skid tester (manufactured by Stanley London Co.), and the index was indicated as an index with Comparative Example 1 being 100. The larger the value, the higher the wet grip performance.

(Dry Grip Performance) A tire of size 195 / 65R15 using the above-described vulcanized rubber for a tread was produced, and the vehicle was run on a dry asphalt road surface on a test course. The test driver evaluated the stability of the control at the time of steering. The larger the value, the higher the dry grip performance.

(Heat generation resistance) Dynamic strain amplitude 2%, frequency 10H using a spectrometer manufactured by Ueshima Seisakusho Co., Ltd.
z, the reciprocal of the value of tan δ when measured at a measurement temperature of 70 ° C. was represented as an index, with Comparative Example 1 being 100. The larger the value, the higher the heat resistance.

(Abrasion resistance) Using a Lambourn type abrasion tester, the test was carried out at room temperature under the conditions of a slip ratio of 20%, and the reciprocal of the amount of abrasion was indicated as an index with Comparative Example 1 being 100. The larger the value, the higher the wear resistance.

The results are shown in Table 1.

[0026]

[Table 1]

As is clear from Table 1, the average particle diameter is 1
Examples 1 to 4 using a crosslinked polyacrylic ester or crosslinked methyl methacrylate having a thickness of
6, the wet grip performance, the wear resistance and the heat generation resistance could be improved without lowering the dry grip performance.

[0028]

The rubber composition for a tire tread according to the present invention can provide a tire having significantly improved wet grip performance, abrasion resistance and heat generation resistance while maintaining dry grip performance.

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Claims (3)

[Claims] 1. A natural rubber and / or a diene rubber, (B) polyacrylate particles having an average particle diameter of 1 to 200 μm, polymethyl methacrylate particles or crosslinked particles thereof, and (C) a filler for reinforcement And the content of the particles (B) is 1 to 20 parts by weight, and the total content of the particles (B) and the reinforcing filler (C) is 30 to 100 parts by weight based on 100 parts by weight of the rubber (A). A rubber composition for a tire tread, which is 200 parts by weight. 2. The reinforcing filler (C) is carbon black or a general formula (1): nM · xSiO _y · zH ₂ O (1) (where M is a group consisting of aluminum, calcium, magnesium and titanium) Represents at least one selected metal element, oxide or hydroxide, n is 1 to 5,
x represents a numerical value in the range of 0 to 10, y represents a numerical value in the range of 2 to 5, and z represents a numerical value in the range of 0 to 10. 2. The rubber composition for a tire tread according to claim 1, which contains inorganic compound particles represented by the formula (1). 3. A tire using the rubber composition for a tire tread according to claim 1 or 2 for a tread.