JP2000016028A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire equipped with an excellent on-ice performance without sacrificing the stability and controllability, unlikelihood of eccentric wear, or anti-abrasion. SOLUTION: This pneumatic tire has s tread made from a rubber compound containing 100 parts by wt. diene-based rubber and 3-15 parts by wt. flaky filler having a mean radius of 0.4-4 mm and an aspect ratio of 10-40 being selected from among kaolinite, sericite, mica powder, talc, basic magnesium carbonate, and agalmatolite, wherein the total lengths across the wire width of the siping 1 applied to the surface of the tread should range from 20,000 to 55,000 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having excellent on-ice performance without inferior steering stability, uneven wear resistance and wear resistance.

[0002]

2. Description of the Related Art Conventionally, in the field of tires, it is considered that there are adhesive friction, digging friction and hysteresis friction as factors controlling the friction between a tread rubber and a road surface, which affect the performance of the tire on ice.

[0003] Then, a technique of blending a white filler such as silica to improve the adhesive friction has been proposed, but sufficient performance on ice has not been obtained only by improving the adhesive friction.

[0004] For example, Japanese Patent Application Laid-Open Nos. Hei 4-24103 and Hei 3-33187 disclose a technique in which an inorganic filler is blended to excavate and improve friction. However, when the amount of the filler is increased, the rubber hardness increases, and the adhesive friction is reduced.

Further, in Japanese Patent Application Laid-Open Nos. Hei 7-205617, Hei 5-58116, Hei 4-334607 and Hei 3-38413, the on-ice performance of a tire is increased by increasing the siping of the tire tread. Although a technique for improving the performance is disclosed, there has been a problem that steering stability on a dry road surface is reduced and the uneven wear resistance is poor.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide air having excellent on-ice performance without inferior in steering stability, uneven wear resistance and wear resistance without increasing the number and total length of sipes. The goal is to get tires that contain tires.

[0007]

According to the present invention, kaolinite, sericite, 100 parts by weight of a diene rubber are used.
Mica powder, talc, selected from the group consisting of basic magnesium carbonate and fluorite, a rubber composition containing 1 to 15 parts by weight of a sheet-like filler having an average diameter of 0.4 to 4 mm and an aspect ratio of 10 to 40 The present invention relates to a pneumatic tire having a tread having a total length of 2,000 to 55000 mm in a tire width direction of a siping provided on a ground contact surface of the tread.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, the use of a thin filler in a rubber composition constituting a tread has resulted in a digging of a thin filler protruding from the tread. Not only the friction is improved, but also the laminar filler drops off due to running, and many fine (micro) slits (elongated grooves) are formed on the surface of the tread block, and their edges provide a draining effect, and It has been found that the slit reduces the strain on the surface of the tread rubber and improves the grounding property of the tread rubber. Also, unlike the original siping, such micro slits do not significantly change the rigidity of the tread block, and therefore do not reduce the steering stability and the uneven wear resistance, and have excellent performance on ice. The present invention, which is a pneumatic tire, has been completed.

The diene rubber which can be used in the present invention is not particularly limited as long as it has been conventionally used in the field of tires. For example, natural rubber (NR), butadiene rubber (BR), styrene butadiene Rubber (SBR) and the like can be used, and these can be used alone or in any combination.
Above all, from the viewpoint of improving the performance on ice and snow, N
It is preferable to use R and BR. In this case, the tread is soft even at a low temperature, and the tread can maintain the ground contact property.

Next, the filler used in the present invention will be described. In the present invention, it is selected from the group consisting of kaolinite, sericite, mica powder, talc, basic magnesium carbonate and laurite, in that it is blended with the tread rubber and forms micro slits on the tread rubber surface after falling off. To be used.

Among them, mica powder is preferably used because it has good dispersibility in the rubber composition and easily falls off to form micro slits.

In addition, the filler used in the present invention is mixed with the tread rubber to form micro slits of an appropriate size on the surface of the tread rubber. 10 to 40 sheet-like fillers.

Further, from the viewpoint of improving the performance on ice without deteriorating the wear resistance, the thin plate-like filler has an average minor axis of 0.4 to 2.5 mm and an average aspect ratio of 15 to 50.
Preferably it is 30.

The "aspect ratio" means (average diameter of the sheet-like filler) / (thickness of the sheet-like filler).

The mixing ratio of the lamellar filler may be 1 to 15 parts by weight, preferably 3 to 10 parts by weight, based on 100 parts by weight of the diene rubber.

The rubber composition of the present invention may contain, as components other than the above-mentioned components, commonly used fillers such as silica and carbon black, vulcanizing agents such as sulfur, vulcanization accelerators, mineral oils, process oils and the like. A softening agent such as oil and paraffin wax, an antioxidant, and a compounding agent such as stearic acid and zinc oxide can be appropriately contained as long as the effects of the present invention are not impaired.

The rubber composition constituting the tread of the pneumatic tire of the present invention is prepared by mixing a diene rubber and a thin plate filler by a conventional method, and then, if necessary, appropriately mixing the above compounding agents. It can be obtained by vulcanization.

The rubber composition obtained as described above is
It can be applied to the tread of a tire in the usual way. For example, after the unvulcanized rubber composition is molded into a sheet, the rubber composition may be pasted on a tire base, and vulcanized and molded in a mold having a tread pattern.

An important effect of the present invention is that, as described above, the thin plate-like filler in the tread falls off during running and forms a number of micro slits in the tread contact surface. The shape and size of the micro slit correspond to the thin plate-like filler. This micro slit has the same effect as siping. Therefore, it can be called micro siping. This micro siping has a significantly shorter length per spot and a shallower depth from the tread surface of the siping, so that the influence on the rigidity of the tread block is extremely small as compared with the conventional siping. Further, the micro siping on the tread surface has an effect of alleviating the distortion of the surface when the tread is in contact with the ground, and has a function of improving the contactability of the tread to the road surface. As a result, the performance on ice can be improved without increasing the original siping.

Next, the siping of the pneumatic tire of the present invention on the tread contact surface will be described.

The siping means a groove finely cut in a tread rubber contact surface, and is usually provided not only in the width direction of the tire but also in all directions such as the circumferential direction of the tire. In particular, the siping provided in the width direction of the tire has an effect of improving the on-ice performance of the tire.
However, mere provision of siping may impair the steering stability and uneven wear resistance of the tire. Then, the present inventors considered the total length of the siping in the tire width direction, that is, the total (ΣX) in consideration of the micro slit effect described above.
A range that does not impair the performance was found.

In the pneumatic tire of the present invention, if the sum of the lengths of the sipings provided on the tread surface in the tire width direction is smaller than 20,000 mm, the block rigidity is too high and the tread has poor grounding properties, and the microsiping has a grounding property. When there is no synergistic effect of the drainage property and the drainage property, when it exceeds 55000 mm, the block rigidity of the tire pattern is reduced, and the stability of the dry road surface and the uneven wear property are inferior, so that the total length (サ イ X) of the siping in the tire width direction is reduced. 20000-55
000 mm.

In the present invention, the “sum of the length of the siping in the tire width direction” refers to the sum of the lengths when the siping is projected in the tire radial direction.

FIG. 1 is a schematic plan view of the tread of the pneumatic tire of the present invention. In FIG. 1, A indicates the tire width direction, and 1 indicates siping.

Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited thereto.

[0026]

Example 1 According to the mixing ratio shown in Table 1, a rubber composition constituting the tread of the pneumatic tire of the present invention was produced using a Banbury-type closed mixer.

The sheet-like filler is C-133 (mica powder: average diameter 2.5 m, manufactured by Yamaguchi Mica Industrial Co., Ltd.).
m, aspect ratio 17, thickness 150 μm). Further, in addition to the components shown in Table 1, the following components were blended in all the rubber compositions.

Carbon black (N339) 30 parts by weight Silica (Nipsil VN3 manufactured by Degussa) 20 parts by weight Silane coupling agent (Si69 manufactured by Degussa: bis 2 parts by weight (3-triethoxysilylpropyl) tetrasulfide) Paraffin Wax (softening agent) 2 parts by weight Mineral oil (softening agent) 15 parts by weight Stearic acid 2 parts by weight Zinc white 3 parts by weight Sulfur 1 part by weight N-tert-butyl-2-benzothiazolyl 1.5 parts by weight Sulfenamide ( (Sulfurization accelerator) 1,3-diphenylguanidine (vulcanization accelerator) 0.8 parts by weight

Next, using the obtained rubber composition, a knife blade was attached to the mold so that the total sum of the lengths of the sipes in the tire width direction was as shown in Table 1, and the size was determined to be 175 by a conventional method. / 70R13 of the pneumatic tire 1 of the present invention was manufactured.

The following tests were performed on the obtained tires. Table 1 shows the results.

[Test] Test on Ice The obtained tire was mounted on a domestic car of FF, and the average deceleration G when running at 40 km / h on an ice plate road surface was measured. The value in the case of Comparative Example 1 was set to 100 and indicated by an index. The higher the index, the better the performance on ice.

Driving stability The rounding time on the dry driving stability test road was measured, and the value in Comparative Example 1 was set to 100 and indicated by an index. The larger the index, the better the steering stability.

Uneven wear resistance The degree of heel and toe wear of the block pattern of the tread after running 10000 km was measured by using a depth gauge for the difference in wear between the first and second parts between the blocks and compared.
The higher the number, the better the uneven wear resistance.

Abrasion resistance The average remaining groove of the tread groove after running 20,000 km was measured, and the value in the case of Comparative Example 1 was set to 100 and indicated by an index.
The larger the index, the better the wear resistance.

Comparative Examples 1 and 2 Comparative pneumatic tires 1 and 2 were prepared in the same manner as in Example 1 except that the sum of the siping lengths of the tires was changed to the value shown in Table 1.
Was manufactured and tested in the same manner as in Example 1. Table 1 shows the results.

Comparative Examples 3 to 5 Comparative pneumatic tires 3 to 5 were produced in the same manner as in Example 1, Comparative Examples 1 and 2, except that no thin plate-like filler was used. Was performed. Table 1 shows the results
Shown in

[0037]

[Table 1]

From the results shown in Table 1, it can be seen that by blending a sheet-like filler and applying a specific siping, the deceleration G on ice can be improved without significantly impairing the steering stability, uneven wear resistance and wear resistance. It turns out that it becomes possible.

Examples 2 to 3 and Comparative Examples 6 to 9 Pneumatic tires 2 to 3 and comparative pneumatic tires 6 to 9 were prepared in the same manner as in Example 1 except that the proportions shown in Table 2 were changed.
9 was manufactured and tested in the same manner as in Example 1. Table 2 shows the results. For comparison, Table 2 shows Example 1
The results of Comparative Example 1 are also shown.

In Comparative Example 6, mica powder (average diameter 0.2 mm, aspect ratio 20;
In Comparative Example 7, mica powder (average diameter 6.5 mm, aspect ratio 41, thickness 160 μm), and in Example 2, mica powder (average diameter 0.4 mm, aspect ratio 20, thickness 20 μm) ), In Example 3, and Comparative Examples 8 and 9, mica powder (average diameter 1.7 mm, aspect ratio 28, thickness 60 μm) was used.

[0041]

[Table 2]

From the results shown in Table 2, when the average particle size of the thin plate-like filler is smaller than 0.4 mm, the effect of improving the performance on ice is small and the effect is larger than 6.5 mm, and when the aspect ratio exceeds 40, the abrasion resistance is poor. It turns out that.

[0043]

According to the present invention, a pneumatic tire having excellent on-ice performance can be obtained without inferior in handling stability, uneven wear resistance and wear resistance.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a tread of a pneumatic tire of the present invention.

[Explanation of symbols]

 1 siping

Claims (1)

[Claims] [Claim 1] With respect to 100 parts by weight of a diene rubber,
Selected from the group consisting of kaolinite, sericite, mica flour, talc, basic magnesium carbonate and fluorite,
A tread made of a rubber composition containing 1 to 15 parts by weight of a lamellar filler having an average diameter of 0.4 to 4 mm and an aspect ratio of 10 to 40, and a tire width direction of a siping applied to the tread contact surface Sum of lengths in 20000-5
A pneumatic tire that is 5000 mm.