JP2002211203A - Studless tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a studless tire capable of improving iced road driving performance without spoiling operating performance and abrasion resistance on a dry road. SOLUTION: This studless tire uses a rubber composition including a 3-40 pts.wt. of water soluble starch of which the average grain diameter is not less than 20 μm against 100 pts.wt. of diene system rubber used in a tread.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a studless tire, and more particularly to a studless tire having good performance on ice and snow.

[0002]

2. Description of the Related Art Conventionally, when a car travels in winter in a snowy cold region, a spike tire having a spike applied to the tire or a tire chain attached to the outer periphery of the tire is used. I was secure in. However, spiked tires or tires equipped with a tire chain are liable to cause road wear, which becomes dust and causes pollution, which is a major environmental problem.

In order to solve such safety problems and environmental problems, studless tires having braking and driving properties on snowy roads and icy roads without using spikes or chains have rapidly become widespread.

For example, automobile tires having improved performance on ice by blending sand in tread rubber (JP-A-61-150803) or blending metal fibers (JP-A-63-34026). However, since these tires have a relatively high rubber hardness, the effect of friction on ice was insufficient. In addition, the sand, metal fibers, and metal are scattered due to the wear of the tire, causing dust pollution, which may be a social problem.

It has also been proposed to use foamed rubber for the tread rubber (JP-A-62-283001, JP-A-63-9042, JP-A-1-1185).
No. 42). However, for tires using foam rubber,
Although the frictional force on ice and snow is improved, the block effect of the foamed rubber is low, so that the edge effect and drainage effect due to the closed cells cannot be sufficiently utilized, and the abrasion resistance and maneuverability on dry road surfaces are poor. In addition, because it foams in the vulcanization process during manufacturing,
Variations in tire dimensional accuracy are likely to occur.

Further, there is disclosed a technique for improving the performance on ice and snow by blending hollow fine particles with tread rubber (JP-A-11-35736, JP-A-6-328906).
No.). However, in the tire containing the hollow fine particles, there is a problem that the hollow fine particles are broken during kneading, and sufficient performance on ice and snow cannot be exhibited.

Further, there is disclosed a technology relating to a tire which aims at improving the performance on ice and snow by blending a tread rubber with a water-absorbing synthetic polymer and removing the water on the road surface and the tire tread portion (Japanese Patent Laid-Open No. Hei 5 (1993) -5). -148390). However, synthetic polymers do not have sufficient water absorption capacity, and because synthetic polymers do not fall off immediately after water absorption, the effect of improving the performance on ice and snow by the edge effect after the particles of the synthetic polymer fall off is also sufficient. It is hard to say.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a studless tire capable of improving performance on ice and snow without impairing maneuverability and wear resistance on a dry road.

[0009]

According to the present invention, there is provided a studless tire using, as a tread, a rubber composition containing 3 to 40 parts by weight of a water-soluble starch having an average particle diameter of 20 μm or more based on 100 parts by weight of a diene rubber. About.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the studless tire of the present invention, performance on ice and snow can be greatly improved by using a rubber composition containing a water-soluble starch in a diene rubber for a tread.

As the diene rubber, for example, natural rubber, isoprene rubber, styrene-butadiene rubber,
Examples thereof include chloroprene rubber and acrylonitrile-butadiene rubber, and a mixture thereof can also be used.

As the water-soluble starch, soluble starch obtained by allowing a diluted inorganic acid or organic acid to act on the raw starch, or by adding heat to the raw starch, or by using heat in combination with an acid or alkali Dextrin obtained by denaturation can be used, but dextrin is preferably used because it has excellent thermal stability and is soluble in cold water. As raw material starch, potato starch, corn starch, sweet potato starch,
Tapioca starch, sago palm starch, wheat starch,
Rice starch is preferably used.

[0013] Here, the term "water-soluble" refers to cold water at 10 ° C.
It means that 1 g of starch is dissolved in 0 cc within 3 minutes. Starch which does not dissolve in cold water of 10 ° C. within 3 minutes cannot sufficiently improve the performance on ice and snow.

The dextrin includes brown british gum, yellow dextrin, and white dextrin. Among them, yellow dextrin is particularly preferred in terms of heat stability and solubility in cold water. Yellow dextrin is dispersed in rubber without melting or softening even at high temperatures during rubber kneading.

The average particle size of the water-soluble starch is 2
It is 0 μm or more, preferably 20 to 100 μm. If the average particle diameter is less than 20 μm, the effect of improving the performance on ice and snow cannot be sufficiently obtained.

The content of the water-soluble starch is 3 to 40 parts by weight, preferably 5 to 30 parts by weight, based on 100 parts by weight of the diene rubber. If the content is less than 3 parts by weight, the effect of improving the performance on ice and snow will be insufficient, and if it exceeds 40 parts by weight, the wear resistance will decrease.

In the present invention, carbon black, silica, and the like can be blended with the rubber composition as a filler. Examples of the carbon black that can be used in the present invention include, but are not particularly limited to, HAF, ISAF, and SAF.

The total amount of carbon black and silica is 10 to 10 parts by weight of the diene rubber.
Preferably it is 80 parts by weight. If the total amount is less than 10 parts by weight, the abrasion resistance tends to decrease, and if it exceeds 80 parts by weight, the rubber becomes hard, the workability decreases, and the performance on ice and snow tends to decrease.

The rubber composition of the present invention may further contain a process oil such as a paraffinic oil, a naphthenic oil or an aromatic oil. The compounding amount of the process oil is preferably 40 parts by weight or less based on 100 parts by weight of the diene rubber. If the amount of the process oil exceeds 40 parts by weight, the change over time due to the process oil leaking to the rubber surface tends to increase.

The rubber composition of the present invention may contain, in addition to the above-mentioned compounding agents, components and additives generally used in the production of rubber compositions for treads, if necessary, in amounts and compounding amounts usually used. Is also good. Specific examples of the components and additives include, for example, vulcanizing agents (sulfur, sulfur chloride compounds, organic sulfur compounds, etc.), vulcanization accelerators (guanidine, aldehyde-amine, aldehyde-ammonia, thiazole, Sulfenamide-based, thiourea-based, thiuram-based, dithiocarbamate-based, and zandate-based compounds), crosslinking agents (organic peroxide compounds, radical generators such as azo compounds, oxime compounds, nitroso compounds, polyamine compounds, etc.), Reinforcing agents (high impact polystyrene resin, phenol-formaldehyde resin, etc.),
Antioxidants or antioxidants (diphenylamine, p
Amine derivatives such as phenylenediamines, quinoline derivatives, hydroquinone derivatives, monophenols, diphenols, thiobisphenols, hindered phenols, phosphites, etc.), waxes, stearic acid, zinc oxide, softeners , Fillers, plasticizers and the like.

The diene rubber and the water-soluble starch are blended with the other components as necessary, and are usually kneaded in two stages using, for example, a closed kneader such as a Banbury mixer. In the first stage, a compounding agent other than sulfur and a vulcanization accelerator is added, and 120 to 200
Knead at ℃. If the kneading temperature is lower than 120 ° C., the dispersibility of the water-soluble starch, carbon black and silica tends to be low, and if it exceeds 200 ° C., the water-soluble starch tends to deteriorate due to heat. In the second stage,
The sulfur and the vulcanization accelerator are blended and kneaded according to a conventional method.

[0022]

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

Example 1 and Comparative Examples 1 to 5 (Reagent) Natural rubber: RSS # 3 Butadiene rubber: UBEPOL BR manufactured by Ube Industries, Ltd.
150B Carbon black: Show Black N220, manufactured by Showa Cabot Co., Ltd. Microcrystalline wax: Ouchi Shinko Chemical Co., Ltd.
Manufactured by Sunnock N Anti-aging agent: Nocrack 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
(N-phenyl-N '-(1,3-dimethylbutyl)-
(p-phenylenediamine) Stearic acid: Nippon Yushi Co., Ltd. Stearic acid Paraffin oil: Idemitsu Kosan Co., Ltd. Diana Process Oil Zinc flower: Mitsui Mining & Smelting Co., Ltd. Zinc oxide 2 types Water-soluble starch A: Niseki Chemical Yellow dextrin 102D (average particle diameter 35 μm) manufactured by Nippon Shokuhin Kako Co., Ltd. White cellulose (average particle diameter 92 μm) Water-soluble starch C: yellow dextrin 102K (manufactured by Nisseki Chemical Co., Ltd. (average) Water-insoluble starch: Micropearl (average particle diameter: 10 μm) manufactured by Nisse Chemical Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator: Noxeller CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
(N-cyclohexyl-2-benzothiazolylsulfenamide)

(Method of Manufacturing Tire) According to the composition shown in Table 1, first, a reagent other than sulfur and a vulcanization accelerator is kneaded, and then a sulfur composition and a vulcanization accelerator are added and kneaded to obtain a rubber composition. Obtained. The obtained rubber composition was molded into a tread to produce a tire having a tire size of 195 / 65R15.

(Test method) Performance on ice and snow 200 made in Japan with tire size 195 / 65R15
A 0 cc FR vehicle was used to measure the braking stop distance on an ice plate from a speed of 30 km / h. The higher the index, the better the performance on ice and snow. (Brake stop distance of Comparative Example 1) ÷ (Brake stop distance of each combination) × 100

Abrasion resistance In a domestic FF vehicle equipped with a tire size of 195 / 65R15, the groove depth of the tire tread portion at a running distance of 4000 km was measured, and the running distance when the tire groove depth was reduced by 1 mm was calculated. The index of Comparative Example 1 was set to 100 (reference) and converted into an index by the following equation. The larger the index, the better the wear resistance. (Running distance when the groove depth of each composition is reduced by 1 mm) ÷ (Running distance when the groove depth of Comparative Example 1 is reduced by 1 mm) × 100

Maneuverability on a dry road surface A round time was measured on a slalom course on a dry asphalt road surface having a circumference of 500 m, and the index of Comparative Example 1 was set to 100.
It was indexed by the following equation as (reference). The higher the index, the better the maneuverability on dry road surfaces. (Circulation time of Comparative Example 1) ÷ (Circulation time of each formulation) ×
100

The results are shown in Table 1.

Examples 1 and 2 in which 15 parts by weight of a water-soluble starch having an average particle size of 35 μm or 92 μm were blended.
Thus, it was possible to improve the performance on ice and snow without deteriorating wear resistance and maneuverability on a dry road surface.

In Comparative Example 2 in which a small amount of water-soluble starch was blended, the effect of improving the performance on ice and snow was small.

In Comparative Example 3 in which the amount of the water-soluble starch was increased, the abrasion resistance was significantly reduced.

In Comparative Example 4 in which the water-insoluble starch was blended, the effect of improving the performance on ice and snow was small.

In Comparative Example 5 in which a water-soluble starch having a small average particle size was blended, the effect of improving the performance on ice and snow was small.

[0034]

[Table 1]

[0035]

In the studless tire of the present invention, since water-soluble starch is used for the tread, the water-soluble starch existing as particles in the tread portion during running on the ice and snowy road surface is dissolved in the water on the road surface. The unevenness exerts a micro siping effect and a water removing effect, thereby improving the performance on ice and snow. Further, since this phenomenon occurs on the tread surface, the rigidity of the tread block does not decrease, and the maneuverability on a dry road surface is not impaired.

Claims (1)

[Claims] 1. A water-soluble starch having an average particle size of 20 μm or more is added in an amount of 3 to 40 parts by weight based on 100 parts by weight of a diene rubber.
A studless tire using a rubber composition containing parts by weight for a tread.