JP2001001712A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve brake performance on an icy and snowy road through enhancing block rigidity and handling performance by utilizing in a tread of a pneumatic tire at least either one of filling materials of silica and carbon black, water-soluble fibers with specified length, and a rubber compound containing bubbles. SOLUTION: At least either one of filling materials silica and carbon black, water-soluble fibers having a set length of 10 mm or less, and a rubber compound containing bubbles are utilized for a tread of a pneumatic tire. Preferably, a rubber component forming the rubber compound is one that contains 20 wt.% of butadiene or more, and the water-soluble fibers are polyvinyl alcohol fibers. Further, it is preferable that the filling material contains 90 wt.% of silica or more, and 5-20 wt.% of a silane coupling agent with respect to a silica compounding amount. Further, it is preferable that a bubble ratio of the bubble is 5-50 wt.%. With this configuration, drivability and brake performance on wet roads or icy roads are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a technique for further improving on-ice performance and steering stability.

[0002]

2. Description of the Related Art Conventionally, in winter tires, a tread having a cap / base structure has been adopted, and a cap rubber layer has been formed.
By using a large amount of oil, using butadiene rubber, and applying foam rubber, use a relatively soft rubber even at low temperatures to enhance braking performance on ice, while using a relatively hard rubber for the base rubber layer. In addition, the rigidity of the block is ensured, and the steering stability and abrasion resistance on ordinary roads (dry roads, wet roads) and ice and snow roads are improved. However, the conventional method as described above does not have sufficient block rigidity on a general road, and as a result, there are disadvantages such as a decrease in steering stability and a grip force (friction coefficient) on a wet road surface.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to increase the rigidity of a block to further improve the handleability, and to improve the braking performance on an icy and snowy road surface.

[0004]

In order to achieve the above object, the present invention has the following arrangement. (1) A pneumatic tire provided with a tread, wherein at least one filler of silica and carbon black, a water-soluble fiber having a length of 10 mm or less, and a rubber composition containing air bubbles are applied to the tread. Features. (2) The tread has a multilayer structure in the tire radial direction, at least one of which is composed of the rubber composition. (3) The tread has a cap / base structure including a tread side cap rubber layer and a base rubber layer inside the tread side, and at least one of the cap rubber layer and the base rubber layer is formed of the rubber composition. It is characterized by comprising. (4) It is preferable that the rubber component contained in the rubber composition contains 20% by weight or more of butadiene rubber. (5) The amount of the water-soluble fiber contained in the rubber composition is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the rubber component, and the fiber is soluble in water at 0 to 20 ° C. ,
It is preferable that the diameter is 0.01 to 0.1 mm.
Preferably, the fiber is a polyvinyl alcohol fiber. (6) The filler contained in the rubber composition is a rubber component 1
The amount of silica is preferably 90% by weight or less in the filler, and more preferably 5 to 20% by weight of the silica in the filler. (7) Further, it is preferable that the bubble rate of the bubbles is 5 to 50%.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. Water-soluble fibers blended in the rubber composition applied to the tread of the pneumatic tire of the present invention are present dispersed in the rubber composition, the fibers inside reinforce the rubber,
The fiber on the surface retains block rigidity, and if water is present on the road surface, it softens and dissolves due to its water solubility, and the fiber trace becomes an elongated hole, and the internal space of the hole is on the road surface. It drains water, and the periphery of the hole (drainage channel) exerts an edge effect on the road surface, thereby increasing the coefficient of friction on the road surface. Further, as the vehicle travels, the tire tread wears, but the fibers dispersed in the rubber composition appear on the surface sequentially to form new holes, perform the above functions, and perform wet performance and on ice. Improve performance. In addition, the fibers can be oriented in the tire circumferential direction, and in this case, the effect of further improving the maneuverability (handling) can be obtained.

In order to effectively obtain the above-described functions and effects, the water-soluble fiber of the present invention desirably has the following characteristics. The compounding amount is preferably 1 to 20 parts by weight based on 100 parts by weight of the rubber component. If the amount is less than 1 part by weight, the drainage channel is insufficient, and the improvement of the wet performance and the performance on ice is insufficient. If the amount exceeds 20 parts by weight, the Mooney viscosity remarkably increases, and the workability tends to deteriorate. Because there is. The length of the fiber is required to be 10 mm or less, because if it exceeds 10 mm, workability and abrasion resistance decrease. The diameter of the fiber is preferably 0.01 to 0.1 mm from the size of the drainage channel formed after melting. This is because when the thickness is less than 0.01 mm, the drainage action is not sufficient, and when the thickness exceeds 0.1 mm, the actual contact area decreases, and the wettability decreases. Preferably, the fibers are soluble in water at 0-20 ° C. This corresponds to the temperature on the wet road surface and the ice and snow road surface, and the formation of the drainage channel is realized by dissolving in such low-temperature water. According to the method of forming the drainage channel by dissolving in water, the drainage channel formation can be achieved more reliably than the method of forming the drainage channel by detachment. The fiber preferably has a melting point of 180 ° C. or higher. If the temperature is lower than 180 ° C., the material softens and melts during vulcanization, and bubbles are generated in the fiber. Various types of fibers can be used as long as they have the above-mentioned properties. Among them, low-temperature water can be obtained by adjusting the molecular structure while maintaining a high elastic modulus of the fibers affecting the block rigidity. Most preferred are polyvinyl alcohol fibers capable of increasing the solubility in water.

The bubble ratio is preferably 5 to 50%, but if it is less than 5%, a sufficient drainage effect cannot be obtained.
This is because, when it exceeds, the abrasion resistance tends to decrease. The bubble rate (Vs) is calculated by the following equation. Vs (%) = (ρ ₀ / ρ ₁ −1) × 100 where ρ ₁ is the density of the foamed rubber (g / cm ³ ), and ρ ₀ is the density of the solid phase portion of the foamed rubber (g / cm ³ ). It is. The pneumatic tire of the present invention may be of a type in which the entire tread is composed of one kind of tread rubber, or may have a multilayer structure such as a cap / base structure. The effect of the present invention can be obtained by applying such a rubber composition, but it is effective when applied to at least the tread side layer such as a cap rubber. It is preferable that the butadiene rubber is at least 20% by weight in the rubber component in terms of low-temperature characteristics. In the present invention, preferably, the reinforcing filler composed of silica and / or carbon black is used in an amount of 30 to 100 parts by weight based on 100 parts by weight of the rubber component.
The content is 0% by weight or less, more preferably 30 to 90% by weight. If the amount of the filler is less than 30 parts by weight, the reinforcing property cannot be sufficiently obtained, which may affect the breaking property of the rubber composition. If the amount is more than 100 parts by weight, it becomes difficult to disperse the rubber composition in the rubber, which also affects the breaking characteristics of the rubber composition. Because there is. Further, it is preferable that the silane coupling agent is blended in an amount of 5 to 20% by weight of the silica in terms of abrasion resistance and breaking characteristics. The rubber composition according to the present invention may appropriately contain additives which are usually added.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below. According to the composition shown in Table 1, a rubber composition was prepared, and this was applied to a tread rubber (one layer). A tire having a size of 205/65 R15 was produced by a conventional method, and the following properties were measured. It is described in Table 1. Preparation of Water-Soluble Polyvinyl Alcohol (PVA) Fiber As the spinning solution, polyvinyl alcohol unit 75
% Of a polymer having an average degree of polymerization of 500 and a saponification degree of 75% consisting of 25% by mole of vinyl acetate units and 45% by weight of DM.
An SO (dimethyl sulfoxide) solution was used. This spinning solution is extruded from a nozzle into an acetone / DMSO mixed solution (weight ratio 85/15) at 2 ° C., and after passing through a spinning roll, is stretched 4 to 5 times in an acetone / DMSO mixed solution (weight ratio 95/5). And then dried after removing DMSO in acetone. The fiber diameter was adjusted by adjusting the nozzle diameter and the spinning stock solution extrusion speed. After the obtained fibers were bundled thick, they were cut with a guillotine cutter to a desired length.

(1) Driving stability (feeling test) On a test course, an actual vehicle was run, and drivability, braking performance,
The handle responsiveness and the controllability at the time of steering were comprehensively evaluated. The higher the value, the better. (2) Wet braking performance The test tires were mounted on four wheels of a passenger car, braked at 70 km / hour on a wet road surface by spraying water, and the running distance from when the tires were locked to when the vehicle was stopped ( The braking distance) was measured, and the reciprocal of the distance was expressed as an index, with Comparative Example 1 being 100. The higher the value, the better. (3) Braking performance on ice Same as above except that the road surface was an ice road surface having a surface temperature of -5 ° C and braking was performed at 20 km / h.

[0010]

[Table 1] * 1 JSR Corporation * 2 Tokai Carbon Co., Ltd. Seast 7H (N ₂ SA)
126m ² / g) * 3 Nip Seal AQ (N
₂ SA 200 m ² / g) * 4 Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa AG * 5 Spindle oil * 6 N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylene Diamine: 6C * 7 Diphenylguanidine * 8 Dibenzothiazyl disulfide * 9 N-tert-butyl-2-benzothiazylsulfenamide * 10 Azodicarbonamide ADC manufactured by Eiwa Chemical Co., Ltd.
A

[0011] From the above results, both embodiments, steering stability,
Wet braking performance and braking performance on ice are all improved.

[0012]

According to the present invention, the performance on ice can be greatly improved, and the steering stability can also be improved.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08K 5/548 C08K 5/548 7/02 7/02 C08L 9/00 C08L 9/00 // (C08L 9/00 29 : 04)

Claims (11)

[Claims] 1. A pneumatic tire provided with a tread, wherein at least one of silica and carbon black is provided.
A pneumatic tire, characterized in that a rubber composition containing various fillers, water-soluble fibers having a length of 10 mm or less, and air bubbles is applied to a tread. 2. The pneumatic tire according to claim 1, wherein the tread has a multilayer structure in a tire radial direction, at least one of which is formed of the rubber composition. 3. The tread has a cap / base structure including a tread side cap rubber layer and a base rubber layer inside the tread side, and at least one of the cap rubber layer and the base rubber layer is the rubber composition. The pneumatic tire according to claim 1, wherein: 4. The pneumatic tire according to claim 1, wherein the rubber component contained in the rubber composition contains 20% by weight or more of butadiene rubber. 5. The method according to claim 1, wherein the amount of the water-soluble fiber contained in the rubber composition is 1 to 20 parts by weight based on 100 parts by weight of the rubber component. Pneumatic tire. 6. The water-soluble fiber contained in the rubber composition is 0%.
The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire is soluble in water at a temperature of -20 ° C. 7. The water-soluble fiber contained in the rubber composition,
The pneumatic tire according to any one of claims 1 to 6, having a diameter of 0.01 to 0.1 mm. 8. The pneumatic tire according to claim 1, wherein the water-soluble fibers contained in the rubber composition are polyvinyl alcohol fibers. 9. The rubber composition, wherein a filler contained in the rubber composition is 30 to 100 parts by weight with respect to 100 parts by weight of the rubber component, and silica is 90% by weight or less in the filler. Item 10. The pneumatic tire according to any one of Items 1 to 8. 10. The pneumatic tire according to claim 1, wherein a silane coupling agent is further added to the rubber composition in an amount of 5 to 20% by weight based on the amount of silica. 11. The pneumatic tire according to claim 1, wherein the air bubble has an air bubble ratio of 5 to 50%.