JPH0438209A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve a frictional force on an ice road without deteriorating travel performance on a general road by constituting the tread part of a mixture made by way of mixing a low hardness vulcanized rubber component and a staple in matrix rubber. CONSTITUTION:A pneumatic tire A consists of a pair of right and left bead parts 11, a pair of right and left side walls 12 connected to the bead parts 11 and a tread part 13 arranged between the former two. Thereafter, a carcass layer 14 is installed over between the pair of the right and left bead parts 11 and a belt layer 15 is arranged to surround its outer periphery on the tread part 13. The tread part 13 is constituted of a mixture made by way of mixing a low hardness vulcanized rubber component and a staple with matrix rubber. In this constitution, as it is possible to compensate lowering of block rigidity of the tread part due to mixture of the low hardness vulcanized rubber component by means of staple, it is needless to heighten hardness of matrix rubber and it is possible to heighten its adhesion efficiency.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention improves frictional force (braking performance, driving performance) on icy and snowy roads, especially friction on ice, without impairing running performance on general roads (dry roads, wet roads). Concerning studless pneumatic tires with improved power.

[Conventional technology]

Conventionally, when driving a car in winter in a snowy and cold region, safety on snowy and icy roads is ensured by using spiked tires with spikes driven into the tires or by attaching tire chains to the outer circumference of the tires. There is. However, tires equipped with spiked tires or tire chains are susceptible to road wear and damage, which becomes dust and causes pollution, posing a major environmental problem.

In order to solve these safety and environmental problems, studless tires that have braking and driving performance on snowy and icy roads without the use of spikes or chains are rapidly becoming popular.

For this studless tire, a low hardness vulcanized rubber composition with a high adhesion effect (the tread surface adheres to the waterway surface and follows the surface shape of the waterway surface) is blended into the matrix rubber to improve friction on ice. A tire with a trend part has been proposed (Japanese Patent Laid-Open No. 63-9265).
No. 9, Japanese Unexamined Patent Publication No. 172750/1983). However, in this case, the hardness of the matrix rubber must be increased in order to improve running performance on ordinary roads, which reduces the adhesion effect of the matrix rubber, resulting in a reduction in friction on ice while maintaining running performance on ordinary roads. It was not possible to sufficiently measure the improvement in power.

[Problem to be solved by the invention]

An object of the present invention is to provide a studless pneumatic tire that has improved frictional force on icy and snowy roads without impairing running performance on dry or wet road surfaces.

[Means to solve the problem]

The pneumatic tire of the present invention is characterized in that the tread portion is formed by blending a low hardness vulcanized rubber composition and short fibers into a matrix rubber.

In this way, in the present invention, since the short fibers are blended into the matrix rubber in addition to the low hardness vulcanized rubber composition, the short fibers can compensate for the decrease in block rigidity in the trend part due to the blending of the low hardness vulcanized rubber composition. This eliminates the need to increase the hardness of the matrix rubber. therefore,
Since the adhesion effect of the matrix rubber can be enhanced, combined with the adhesion effect of the low hardness vulcanized rubber composition, it is possible to improve the running performance on ice and snow roads without impairing the running performance on ships. Become.

This means will be explained in detail below with reference to the drawings.

The figure is an explanatory half-sectional view in the meridian direction of the pneumatic tire of the present invention. In this figure, the pneumatic tire A of the present invention has a pair of left and right bead portions 11°11 and these bead portions 11
．． A pair of left and right sidewall parts 12.1 connected to 11
2 and a tread portion 13 disposed between these sidewall portions 12 and 12. Pair of left and right bead parts 11.11
A carcass layer 14 is installed in between, and the trend part 1
3, a belt layer 15 surrounds this outer periphery.
is located. 10 is the tread surface.

In the present invention, the tread portion 13 is composed of a compound in which a low hardness vulcanized rubber composition and short fibers are blended into a matrix rubber.

(1) Matrix rubber.

Although not particularly limited, natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, or a blend thereof is preferably used.

Compounding agents such as carbon black and a softener are appropriately added to this matrix rubber by a conventional method.

(2) Low hardness vulcanized rubber composition.

A rubber compound is prepared in advance and then vulcanized.

As the rubber used here, for example, natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, halogenated butyl rubber, or a blend of two or more of these can be used. Compounding agents such as a carbon blank and a softener are appropriately blended.

However, the amount of carbon black blended is preferably smaller than that of the matrix rubber, specifically, preferably % or less. This is because if the amount is too large, the vulcanized rubber composition becomes hard.

The hardness of this low hardness vulcanized rubber composition is JIS hardness (JI
S Hs , 0° C.) is 30-50. Also, the shape is
It is rod-shaped, cubic, granular, or similar. The average particle size is 3IllI11 or less, preferably 1 to 2
It is mm. If it exceeds 3 mm, there is a risk that running performance on ordinary roads will deteriorate.

The blending amount of the low hardness vulcanized rubber composition is as follows: matrix rubber 1
The amount may be about 5 to 80 parts by weight per 00 parts by weight.

By blending this low hardness vulcanized rubber composition, it is possible to enhance the adhesion effect of the trend portion.

(3) Short fibers.

Average length: 10 to 5000 μm (preferably 1000 to 5000 μm)
3000 μm) and a length/diameter ratio of 10 to 1000. Average length less than 10 μm, length/diameter ratio 10
If it is less than that, no reinforcing effect will be produced. Also, the average length is 5000
If it exceeds μm or the length/diameter ratio exceeds 10QO, it will be difficult to process the tread and 7-dot portions.

The short fibers are not particularly limited, and for example, natural fibers such as cotton and silk, chemical fibers such as cellulose fibers, and polyamide fibers can be used.

The blending amount of the short fibers may be 1 to 20 parts by weight per 100 parts of the matrix rubber.

Examples and comparative examples are shown below.

Examples and Comparative Examples Various tires with a tire size of 185/70 R1385Q whose tread portion was configured with the formulation contents (parts by weight) shown in Table 1 were prepared, and these tires (conventional example, Examples 1 to 2,
Comparative Examples 1 and 2) were evaluated as follows. The results are shown in Table 1. The test vehicle used was a 1600cc FF vehicle.

J4- above: The vehicle ran on an ice floe at an initial speed of 30 km/h, and the braking distance when braking was measured and expressed as an index with the conventional tire (conventional example) set as 100. The larger the value, the better the braking.

At Teio 2: A test was carried out on a 5% (2.9°) slope on a smooth, compacted snow road by repeatedly braking a passenger car on a compacted snow road, and the acceleration time for a 30m section using the zero starting method was determined. It was measured and expressed as an index compared to conventional tires. The larger the value, the better the drive performance.

°(): The feeling of each tire was scored by 5 test drivers using a 10-point system, and the results (average value) were expressed as an index relative to the conventional tire. The larger the value, the better the steering stability.

(): Dry road surface under the conditions of design normal load and air pressure specified by JATMA. After traveling OOOkm, the amount of wear on each tire was expressed as an index relative to the amount of wear on conventional tires. The larger the value, the better the wear resistance.

4■S　HsbaO”C): Conforms to JIS K 6301 (0°C).

・Young (MPa): Cut a sample from the tread part of each test tire,
Using a viscoelastic spectrometer manufactured by Toyo Seiki ■, a sample with a length between chucks of 20 tm, a width of 5 troughs, and a thickness of 21 cm was subjected to a frequency of 20 t (z, initial strain of 10%, dynamic strainer of 2%, temperature of 0°C).
Measured under the following conditions. The larger the value, the greater the rigidity.

(Margin below the device) Note) Book 1 Short fiber A: Cellulose short fiber (Santoweb D manufactured by Mitsubishi Monsanto Kasei ■).

Chapter 2 Adhesive aid: Hexamethoxymethylmelamine (Regimen 3520 manufactured by Mitsubishi Monsando Kasei ■).

Book 3: Low hardness rubber: granular vulcanized rubber made of pure natural rubber, particle size: lll1m, length: 1.11° In Table 1, the conventional example is a conventional studless tire, cut rubber (low hardness vulcanized rubber). composition), does not contain short fibers. Example 1.2 is a tire containing the cut rubber and short fibers of the present invention, which can achieve both ice and snow performance and general performance. Comparative Example 1 contains cut rubber but does not contain short fibers (the matrix rubber is hard), so the running performance on icy and snowy roads is somewhat good, but the running performance on ordinary roads is slightly degraded. Comparative example 2 is
Although it contains cut rubber but does not contain short fibers (the matrix rubber is softer than Comparative Example 1), the running performance on ice and snow roads is somewhat good, but the running performance on ordinary roads is lower than that of Comparative Example 1.

〔Effect of the invention〕

As explained above, according to the present invention, since the trend portion that comes into contact with the road surface is composed of a compound obtained by blending a low hardness vulcanized rubber composition and short fibers into a matrix rubber, -
It becomes possible to significantly improve the frictional force on icy and snowy roads without impairing running performance on shipping routes (dry roads, wet roads).

[Brief explanation of drawings]

The figure is an explanatory half-sectional view in the meridian direction of the pneumatic tire of the present invention. 10...Trend surface, 11...Bead part, 12.
...Side wall, 13...Trend section, 14...
・Carcass layer.

Claims (1)

[Claims] A pneumatic tire whose tread portion is formed by blending a low hardness vulcanized rubber composition and short fibers into a matrix rubber.