JP2001214003A - Rubber composition for tire and pneumatic tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain both a rubber composition for a tire having excellent braking performance and stability on a wet road surface and excellent abrasion resistance and a pneumatic tire using the same. SOLUTION: This rubber composition for tire comprises (A) a rubber component composed of 80-95 wt.% of a styrene-butadiene rubber and 20-5 wt.% of natural rubber and (B) 10-100 pts.wt. based on 100 pts.wt. of the rubber composition of aluminum hydroxide powder. This pneumatic tire uses the rubber composition as a tread rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber composition for a tire and a pneumatic tire using the same. More specifically, the present invention relates to a rubber composition for a tire having excellent braking performance and steering stability (wet grip performance) on a wet road surface and the like, and having good abrasion resistance, and a pneumatic tire using the same. is there.

[0002]

2. Description of the Related Art In recent years, with the increasing speed of automobiles, the characteristics required for tires have become stricter year by year, and various performances on wet road surfaces during high-speed running are mentioned as one of them. In order to improve braking performance and handling stability on wet road surfaces during high-speed running, grip performance on the road surface and block rigidity of the tire tread pattern should be increased, and block deformation during cornering To improve cornering characteristics, prevent deformation of grooves formed in the tire tread, smoothly drain water, and prevent hydroplaning. In order to increase the grip force on a wet road surface, it is important to increase the frictional force with the road surface by increasing the hysteresis loss of the tread rubber. In other words, the tread surface that is rubbing against the road surface is deformed at a high speed due to the fine unevenness of the road surface, and the larger the energy dissipation caused by the hysteresis loss generated in this periodic deformation process, the larger the friction force Become. In order to achieve high hysteresis loss of tread rubber, for example, silica or aluminum hydroxide is mixed with carbon black as a reinforcing filler in high molecular weight styrene-butadiene copolymer rubber with excellent mechanical properties. That is being done. However, when aluminum hydroxide is blended as a reinforcing filler, the wet grip property is improved, but the abrasion resistance is reduced. Therefore, the amount of the aluminum hydroxide used is limited, and the desired wet grip property is hardly obtained. there were.

[0003]

SUMMARY OF THE INVENTION The present invention provides a rubber composition for a tire which is excellent in braking performance and steering stability on a wet road surface and the like and has good abrasion resistance under such a circumstance. An object of the present invention is to provide a pneumatic tire.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have used a rubber component containing styrene-butadiene rubber and natural rubber in a specific ratio, and As a reinforcing filler, at least aluminum hydroxide powder is compounded at a predetermined ratio with respect to the rubber component, so that a wet grip property is improved by a synergistic effect of natural rubber and aluminum hydroxide powder, It has been found that a rubber composition having a well-balanced wet grip property and abrasion resistance can be obtained, and the object can be achieved. The present invention has been completed based on such findings. That is, the present invention relates to (A) 80-95% by weight of styrene-butadiene rubber and 20-5% by weight of natural rubber.
(B) per 100 parts by weight of a rubber component consisting of
A rubber composition comprising 10 to 100 parts by weight of aluminum hydroxide powder. Also,
The present invention also provides a pneumatic tire using the above rubber composition for a tread rubber.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the rubber composition of the present invention,
As the component (A), a mixture of styrene-butadiene rubber and natural rubber is used. Here, the styrene-butadiene rubber preferably contains 20 to 60% by weight of a styrene unit. When the content of the styrene unit is 2
If the content is less than 0% by weight, the wet grip properties of the obtained rubber composition may be insufficient. On the other hand, if the content is more than 60% by weight, the block rigidity is unnecessarily high, and the rubber is less likely to bite into the road surface. It is difficult to obtain the wet grip property. From the viewpoint of wet grip properties, a more preferable content of the styrene unit is in the range of 30 to 45% by weight. The content ratio of the styrene-butadiene rubber to the natural rubber in the component (A) is 80 to 95% by weight for the styrene-butadiene rubber and 20 to 5% for the natural rubber.
It must be in the range of weight percent. When the content of the natural rubber is less than 5% by weight, the effect of improving the wet grip property is not sufficiently exhibited. On the other hand, when the content exceeds 20% by weight, the effect of improving the wet grip property is not so much recognized for the amount. Abrasion resistance decreases.

[0006] In the rubber composition of the present invention, aluminum hydroxide powder is used as the component (B). The aluminum hydroxide powder preferably has an average particle size of 5 μm or less. If the average particle size exceeds 5 μm, the reinforcing effect is not sufficiently exhibited, and the abrasion resistance may be reduced. On the other hand, if the average particle size is too small, aggregation of the particles becomes strong, and it becomes difficult to disperse the particles in the rubber properly, so that a rubber composition having desired performance may not be obtained.
Therefore, the average particle size of the aluminum hydroxide powder is more preferably in the range of 0.1 to 5 μm, and in particular, 0.1 to 5 μm.
A range of 3 μm is preferred. In the present invention, the aluminum hydroxide powder of the component (B) is blended in an amount of 10 to 100 parts by weight based on 100 parts by weight of the rubber component of the component (A). If the amount is less than 10 parts by weight, the effect of improving wet grip properties is not sufficiently exhibited,
On the other hand, if it exceeds 100 parts by weight, the wear resistance is significantly reduced,
It cannot be put to practical use. In consideration of the effect of improving wet grip properties and abrasion resistance, the amount of the component (B) is preferably in the range of 20 to 60 parts by weight, particularly preferably 20 to 4 parts by weight.
A range of 0 parts by weight is preferred.

In the rubber composition of the present invention, carbon black and / or silica powder is usually used as the component (C) together with the aluminum hydroxide powder of the component (B) as a reinforcing filler. The carbon black is not particularly limited, and any one can be selected from those conventionally used as a reinforcing filler for rubber. Examples of the carbon black include FEF, SRF, HAF, ISAF, SAF and the like. Preferably, the iodine adsorption amount (IA) is 60 mg
/ G or more and dibutyl phthalate oil absorption (DB
P) is carbon black of 80 ml / 100 g or more. By using this carbon black, the effect of improving various physical properties is increased, but in particular, HAF, ISAF, and SAF, which are excellent in wear resistance, are preferable.

On the other hand, the silica powder is not particularly limited, and can be arbitrarily selected from those conventionally used as a reinforcing filler for rubber. Examples of the silica include wet silica (hydrous silicic acid), dry silica (silicic anhydride), calcium silicate, aluminum silicate, and the like. Remarkable wet silica is preferred. In the present invention, as the reinforcing filler of the component (C), only carbon black may be used, only silica powder may be used, or carbon black and silica powder may be used in combination. Good. The amount of the component (C) is selected in the range of 60 to 150 parts by weight based on 100 parts by weight of the rubber component (A). If this amount is less than 60 parts by weight, the desired high hysteresis loss, fracture characteristics and wear resistance cannot be obtained,
If it exceeds 150 parts by weight, workability and the like will be reduced. In consideration of the physical properties and processability of the rubber composition, the amount of the component (C) is preferably 80 to 140 parts by weight, and more preferably 90 to 130 parts by weight.

In the present invention, when silica powder is used as the component (C), a silane coupling agent can be added as the component (E), if desired. There is no particular limitation on the silane coupling agent, and any known silane coupling agent conventionally used in rubber compositions, for example, bis (3-triethoxysilylpropyl) polysulfide,
γ-mercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane and the like can be used. . The amount of the silane coupling agent optionally used is generally selected in the range of 1 to 20% by weight based on the silica powder of the component (C).
If the amount is less than 1% by weight, the effect as a coupling agent is not sufficiently exhibited, and if it exceeds 20% by weight, gelation of the rubber component may be caused. From the viewpoints of the effect as a coupling agent and the prevention of gelation, the preferable amount of the silane coupling agent is in the range of 5 to 15% by weight. In the rubber composition of the present invention, a softener is usually used as the component (D).

The softener is not particularly limited, and may be appropriately selected from those conventionally used in rubber compositions. These softeners are roughly classified into mineral oils, vegetable oils, and synthetic oils. In the present invention, mineral oils are preferably used. Examples of the mineral oils include paraffinic process oils, naphthenic process oils, petroleum process oils such as aromatic process oils, polymerized high-boiling strong aromatic oils, liquid paraffin, and white oil. Of these, petroleum-based process oils, particularly aromatic-based process oils, are preferred. In the present invention, the compounding amount of the (D) component softener is determined by the rubber component 100 (component (A)).
It is selected in the range of 40 to 180 parts by weight with respect to parts by weight. If the amount is less than 40 parts by weight, sufficient hysteresis loss cannot be obtained, and thus desired exercise performance cannot be obtained. On the other hand, if it exceeds 180 parts by weight, sufficient dispersion of the reinforcing filler cannot be obtained, so that workability and wear resistance tend to decrease. In consideration of exercise performance, workability, wear resistance and the like, the amount of the softening agent is preferably in the range of 40 to 130 parts by weight, and particularly preferably in the range of 50 to 110 parts by weight.

The rubber composition of the present invention may contain, if desired, various chemicals usually used in the rubber industry, such as vulcanizing agents, vulcanization accelerators, antioxidants, as long as the object of the present invention is not impaired. An anti-scorch agent, zinc white, stearic acid and the like can be contained. Examples of the vulcanizing agent include sulfur and the like, and the amount of use is preferably 0.1 to 10.0 parts by weight as sulfur based on 100 parts by weight of the rubber component.
More preferably, the amount is 1.0 to 5.0 parts by weight. 0.1
If the amount is less than 10 parts by weight, the fracture strength and abrasion resistance of the vulcanized rubber may be reduced. Although the vulcanization accelerator that can be used in the present invention is not particularly limited, for example, M (2-
A thiazole-based vulcanization accelerator such as mercaptobenzothiazole), DM (dibenzothiazyldisulfide), or CZ (N-cyclohexyl-2-benzothiazylsulfenamide); or a guanidine-based vulcanization accelerator such as DPG (diphenylguanidine). And its usage is
It is preferably 0.1 to 5.0 parts by weight, more preferably 0.2 to 3.0 parts by weight, based on 100 parts by weight of the rubber component.

The rubber composition for a tire according to the present invention comprises a roll,
It is obtained by kneading using a kneading machine such as an internal mixer, and after molding, vulcanization is performed and used for tire applications such as tire tread, undertread, carcass, sidewall, and bead portion. Particularly, it is suitably used as a rubber for a tire tread. The pneumatic tire of the present invention is manufactured by a usual method using the rubber composition of the present invention. That is, if necessary, the rubber composition of the present invention containing various chemicals as described above is extruded into a member for tread in an unvulcanized stage, and is pasted and molded by a normal method on a tire molding machine. Then, a green tire is formed. The green tire is heated and pressed in a vulcanizer to obtain a tire. The pneumatic tire of the present invention thus obtained has excellent wet grip properties and good wear resistance.

[0013]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The physical properties of the vulcanized rubber were measured according to the following methods. (1) Wet skid performance (gripability on wet road surface) It 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 higher the value, the better the wet skid performance. (2) Abrasion resistance A slip ratio of 2 was measured at room temperature using a lampoon type abrasion tester.
The test was performed under the condition of 5%, and the reciprocal of the wear amount was indicated as an index, with any of the comparative examples being 100. The higher the value, the better.

(3) Fracture characteristics The tensile stress (M ₃₀₀ ) at 300% elongation was measured according to JIS K63.
It was measured according to 01-1995. Examples 1 to 4 and Comparative Examples 1 to 5 Rubber components composed of natural rubber and SBR-1 [0141 manufactured by JSR Corporation, styrene-butadiene rubber having a styrene unit content of 40% by weight] in the ratios shown in Table 1 10
0 parts by weight of carbon black S in the amount shown in Table 1
AF and silica [Nipsil AQ, trade name, manufactured by Nippon Silica Industry Co., Ltd.] and aluminum hydroxide [Showa Denko KK]
Manufactured by Heidilite H-43M, average particle size 1.0μ
m), 3 parts by weight of a silane coupling agent [Si69 manufactured by Degussa AG, bis (3-triethoxysilylpropyl) tetrasulfide], 95 parts by weight of a softening agent (aromatic process oil), stearic acid 2 parts by weight, zinc flower 3 parts by weight, wax 1 part by weight, antioxidant 6
C [N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine] 1.4 parts by weight, vulcanization accelerator DPG (diphenylguanidine) 0.8 part by weight, vulcanization accelerator CZ ( 5 parts by weight of N-cyclohexyl-2-benzothiazylsulfenamide) and 1.2 parts by weight of sulfur were blended to prepare a rubber composition. 145 of this rubber composition
The composition was vulcanized at 60 ° C. for 60 minutes and the physical properties of the vulcanized rubber were measured. The results are shown in Table 1.

[0015]

[Table 1]

[0016]

[Table 2]

As can be seen by comparing Comparative Examples 1, 3, 4, and 5 with Examples 1 to 4, the combined use of natural rubber and aluminum hydroxide improves the wet skid performance due to the synergistic effect. Comparative Example 2 is an example in which 30 parts by weight of natural rubber was blended, and the effect of improving wet skid performance reached a plateau and the wear resistance was further reduced. Example 5 and Comparative Examples 6 and 7 A rubber component 10 comprising natural rubber in the proportions shown in Table 2 and SBR-2 [0120 manufactured by JSR Corporation, styrene-butadiene rubber having a styrene unit content of 35% by weight].
0 parts by weight of carbon black I in the amount shown in Table 2
Reinforcing filler consisting of SAF and aluminum hydroxide (supra), 50 parts by weight of softener (supra), 1.5 stearic acid
Parts by weight, 2.5 parts by weight of zinc white, 2 parts by weight of wax, 2.2 parts by weight of antioxidant 6C (described above), 1.6 parts by weight of vulcanization accelerator DM (dibenzothiazyl disulfide), vulcanization acceleration A rubber composition was prepared by blending 1 part by weight of agent NS (Nt-butyl-2-benzothiazylsulfenamide) and 1 part by weight of sulfur. This rubber composition was vulcanized at 145 ° C. for 40 minutes, and the physical properties of the vulcanized rubber were measured. The results are shown in Table 2.

[0018]

[Table 3]

As can be seen by comparing Comparative Examples 6 and 7 with Example 5, the combined use of natural rubber and aluminum hydroxide improves the wet skid performance due to the synergistic effect. Examples 6 and 7 and Comparative Examples 8 and 9 The amounts of carbon black SAF and silica shown in Table 3 are based on 100 parts by weight of the rubber component composed of natural rubber and SBR-1 (described above) in the proportions shown in Table 3. Reinforcing filler composed of (as described above) and aluminum hydroxide (as described above), 3.5 parts by weight of a silane coupling agent (as described above), 165 parts by weight of a softener (as described above), 2 parts by weight of stearic acid, zinc 3 parts by weight of flower, 1.5 parts by weight of wax, 1.4 parts by weight of antioxidant 6C (described above), 1 part by weight of vulcanization accelerator DM (described above), vulcanization accelerator CZ
2.7 parts by weight (described above) and 1.15 parts by weight of sulfur were blended to prepare a rubber composition. 145 ° C,
The composition was vulcanized for 60 minutes, and the physical properties of the vulcanized rubber were measured. The results are shown in Table 3.

[0020]

[Table 4]

As can be seen by comparing Comparative Examples 8 and 9 with Examples 6 and 7, the combined use of natural rubber and aluminum hydroxide improves the wet skid performance due to the synergistic effect.

[0022]

The rubber composition for a tire according to the present invention uses natural rubber as a part of a rubber component and at least aluminum hydroxide powder as a reinforcing filler. Due to the effect, the wet grip property is improved, and the wet grip property and the abrasion resistance are well-balanced, so that it is suitably used as a tire tread rubber.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C08K 5/01 C08K 5/01 5/548 5/548 // (C08L 9/06 (C08L 9/06 7:00) 7:00)

Claims (7)

[Claims] (1) a styrene-butadiene rubber (A)
A rubber composition for a tire, comprising: a rubber component consisting of 95% by weight and 20 to 5% by weight of natural rubber; and (B) 10 to 100 parts by weight of aluminum hydroxide powder per 100 parts by weight thereof. 2. The rubber composition for a tire according to claim 1, comprising (C) 60 to 150 parts by weight of carbon black and / or silica powder. 3. The rubber composition for a tire according to claim 1, comprising (D) 40 to 180 parts by weight of a softener. 4. The method of claim 1, wherein (E) the silane coupling agent is (C)
The rubber composition for a tire according to claim 2, wherein the rubber composition is contained in an amount of 1 to 20% by weight based on the silica powder as the component. 5. The rubber composition for a tire according to claim 1, wherein the styrene-butadiene rubber as the component (A) contains 20 to 60% by weight of a styrene unit. 6. The rubber composition for a tire according to claim 1, wherein the aluminum hydroxide powder of the component (B) has an average particle size of 5 μm or less. 7. A pneumatic tire using the rubber composition according to any one of claims 1 to 6 as a tread rubber.