JPH03266704A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve frictional function on ice without sacrificing antifrictional characteristic by forming a tread part out of rubber composition which includes water soluble inorganic compound as well as staple, and in which the particles of the water soluble inorganic compound do not practically come into contact with each other. CONSTITUTION:The tread part of a pneumatic tire is formed out of specific rubber composition. The specific rubber composition includes a water soluble inorganic compound as well as a staple, and is formed is such a way that the particles of the water soluble inorganic compound do not practically come into contact with each other. Since the water soluble inorganic compound on the surface of the tread dissolves in the water of the road surface at the time of running on a frozen road surface and unevenness is formed on the tread surface thereby, frictional function on ice can be improved. Since the water soluble inorganic compound in the tread is not dissolved, the tread part will not be in a foaming condition, and antifrictional characteristic is thus not practically sacrificed. The tread part can also be reinforced by the staple.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic tire with improved friction performance on ice.

[Conventional technology]

Frozen road surfaces, especially roads at temperatures around 0° C. where ice and water coexist, are slippery and dangerous for motor vehicles.

Conventionally, in order to enable safe driving on such road surfaces, tire treads have been made of, for example, a rubber material that is soft even at low temperatures, or a foamed rubber material. However, in this case, there is a problem that the wear resistance is poor.

[Problem to be solved by the invention]

The present invention was conceived in view of the above circumstances, and an object of the present invention is to provide a pneumatic tire that has improved friction performance on ice without substantially impairing wear resistance.

[Means to solve the problem]

The pneumatic tire of the present invention includes a tread portion made of a rubber composition containing a water-soluble inorganic compound and short fibers, and in which particles of the water-soluble inorganic compound are not substantially in contact with each other. It is characterized by

As described above, in the present invention, since the rubber composition constituting the tread portion of the tire contains the water-soluble inorganic compound in a state in which the particles are not substantially in contact with each other, the tread surface is The water-soluble inorganic compound dissolves into the water on the road surface, forming irregularities on the tread surface, thereby improving friction performance on ice. Further, since the water-soluble inorganic compound inside the tread portion does not dissolve, the tread portion does not become foamed, so that wear resistance is not substantially impaired.

Furthermore, since the rubber composition that makes up the tread contains short fibers, the tread is reinforced by these short fibers, which prevents cranks from occurring on the unevenness formed on the tread surface. , it is possible to further improve friction performance on ice.

The above means will be explained in detail below.

The water-soluble inorganic compound used here is a “saturated solution 1 at 0°C”.
It has a solubility in water at 0° C. of 1 g or more in 0.0 g.

Examples of water-soluble inorganic compounds include metal chlorides such as potassium chloride, calcium chloride, iron chloride, sodium chloride, barium chloride, and magnesium chloride; nitrates such as potassium nitrate and sodium nitrate; and carbonates such as potassium carbonate and sodium carbonate. Compounds: Examples include sulfuric acid compounds such as zinc sulfate, copper sulfate, and iron sulfate. Among these, it is preferable to use sodium chloride, particularly common salt containing sodium chloride as a main component. This is because salt is easily available and inexpensive. In addition, 90% by weight or more is sodium chloride and/or
Or calcium chloride is preferably used.

The rubber composition used in the present invention contains this water-soluble inorganic compound. Particles of this water-soluble inorganic compound are not substantially in contact with each other within the rubber composition. That is, the individual particles of the water-soluble inorganic compound are substantially independently dispersed within the rubber composition. If the particles are not dispersed in this way, that is, if the particles are in contact with each other, then when the tire tread is made of the rubber composition and the tire is driven on an icy road surface, the water solution inside the trend part will be removed. This is because even the organic inorganic compounds are leached out, creating communicating pores from the tread surface to the inside, and the trend portion becomes foamed to the inside, impairing wear resistance.

In order to substantially independently disperse individual particles of a water-soluble inorganic compound, the water-soluble inorganic compound is blended into a rubber composition, taking into consideration the particle size and blending amount of the water-soluble inorganic compound, and kneaded. good. In other words, when the particle size is large, the amount to be blended is reduced, while when the particle size is small, the amount to be blended is increased (
You can do something like this. The average particle size of water-soluble inorganic compounds is
It is preferable that it is 5-2000 micrometers.

If it is less than 5 μm, dispersion becomes difficult, and if it exceeds 2000 μm, the wear resistance will be significantly deteriorated. The blending amount is approximately 1 to 50% by volume based on the total volume of the rubber composition. If it is less than 1% by volume, no effect can be expected, and if it exceeds 50% by volume, the particles will come into contact with each other, resulting in a low modulus of elasticity and poor wear resistance.

Moreover, the rubber composition used in the present invention contains short fibers. Examples of the short fibers include organic fibers such as vinylon fibers, polyester fibers, nylon fibers, cotton, hemp, and rayon fibers; and inorganic fibers such as glass fibers, carbon fibers, silicon carbide whiskers, and graphite fibers. The short fibers preferably have an average length of 10 to 5000 μm and an aspect ratio (length/average diameter ratio) of 10 to 1000. Average length is 10I! If the thickness is less than 5,000 μm, no effective reinforcing effect will be exhibited, and if it exceeds 5,000 μm, the fibers will bunch together, making dispersion impossible. Further, fibers with an aspect ratio of less than 10 do not provide sufficient reinforcement, and fibers with an aspect ratio of more than 1000 result in poor dispersibility.

Note that it is preferable to use short fibers that have been surface-treated to facilitate adhesion to rubber. These short fibers may be in contact with each other in the rubber composition, or may be in contact with particles of a water-soluble inorganic compound. The blending amount of the short fibers is about 0.1 to 10% by volume based on the total volume of the rubber composition.

The rubber constituting the rubber composition is not particularly limited, and examples include diene rubbers such as natural rubber, synthetic polyisoprene rubber, polybutadiene rubber, and styrene-butadiene copolymer rubber. This rubber composition is
Contains other compounding agents such as carbon black as appropriate.

The pneumatic tire of the present invention has a tread portion made of the above rubber composition. It is sufficient that at least the contact surface of this tread portion is made of the above-mentioned rubber composition. In this case, the rubber composition accounts for 10% of the total area of the tread.
It is preferable that the amount of

Examples are shown below.

EXAMPLE Rubber compositions A to H were prepared with the formulation contents (parts by weight) shown in Table 1, and the coefficient of friction on ice of these rubber compositions was measured by the following method to evaluate the friction performance on ice. Also,
Wear resistance was evaluated by measuring the Pico wear index. These results are shown in Table 1.

Top, ": Vulcanization of the sample was performed at 160° C. for 20 minutes using a pressure press. The surface of the sample was puffed with #80 sandpaper before the test.

Measurements are made using an ASTM portable skin tester.
It was carried out using E-303. The road surface used was a water basin set at -5°C. The obtained coefficient of friction on ice was expressed as an index with the case of rubber composition A set as 100. A larger number indicates a higher coefficient of friction on ice.

Pico': Performed according to ASTM D-2228. The larger the number, the higher the wear resistance.

(Margins below this page) Note) Umbrella 1: N-(1,3-dimethylbutyl)-N'-phenyl-P-phenylenediamine.

12: N-cyclohexyl-2-benzothiazolylsulfenamide.

Usa 32 "Ki-Chin Salt" (trade name) manufactured by Japan Tobacco Inc. was ground in a ball mill, passed through a 200-mesh sieve, and sampled after passing through a 330-mesh sieve. The average particle size was 55μ.

Rate 42 "Kitchen Salt" (trade name) manufactured by Japan Tobacco Inc. was ground in a ball mill, passed through a 70-mesh sieve, and sampled what remained on an 83-mesh sieve.

The average particle size was 195 μm.

Rate 52 "Kitchen Salt" manufactured by Japan Tobacco
(trade name) was dissolved in water, and the recrystallized grains were dried, passed through a 4-mesh sieve, and those that passed through a 4.7-mesh sieve were sampled. The average particle size was 4.2 mm.

Book 6: First-class reagent. Average particle size 250 μm.

Rate 7: "Santoweb D" manufactured by Mitsubishi Non-Sand (cellulose short fibers surface-coated with SBR).

*82 “Regimen” manufactured by Mitsubishi Monsando (hexamethylenetetramine ten-stable).

From Table 1, rubber compositions F and G contain a water-soluble inorganic compound (salt) and short fibers in a state where the particles are not substantially in contact with each other.

It can be seen that Rubber Composition A, which does not contain a water-soluble inorganic compound, is superior in friction performance on ice without substantially impairing wear resistance (picowear index). In addition, compared to rubber compositions B, C, and D, which contain a water-soluble inorganic compound (salt) but do not contain short fibers in a state where the particles are not substantially in contact with each other, water-soluble inorganic compounds and short fibers Rubber compositions F and G containing both.

It can be seen that H is even more excellent in wear resistance and friction performance on ice.

Next, pneumatic tires with a tire size of 185/70 R13 were prepared by forming trend parts with rubber compositions A, F, and G (Comparative Tire I, Inventive Tire I, Inventive Tire 2). Each of these tires was installed on a domestically produced five-seat sedan, and the vehicle was run on an icy road surface with a temperature of -8℃ at a temperature of -12℃.The braking and stopping distance from a speed of 30k+w/h was measured, and the braking distance was calculated using the following formula. The index was calculated. The results are shown in Table 2. The larger the value, the higher the friction performance on ice.
From Table 2, it can be seen that tires 1 and 2 of the present invention are superior to comparative tire 1 in terms of friction performance on ice.

(Margins below this page) ■Table L [Effects of the Invention] As explained above, the pneumatic tire of the present invention contains a water-soluble inorganic compound in a state where the particles are not substantially in contact with each other, and has a short Since the tread portion of the tire is made of a rubber composition containing fibers, it is possible to improve friction performance on ice without substantially impairing wear resistance.

Claims (1)

[Claims] A pneumatic tire comprising a tread portion made of a rubber composition containing a water-soluble inorganic compound and short fibers, in which particles of the water-soluble inorganic compound are not substantially in contact with each other.