JPH1025367A - Tread rubber composition for studless tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition, exhibiting excellent braking property on frozen road or on snowy road without damaging the road surface, and good in processability, dispersibility and durability by blending a tread rubber component with a synthetic fiber having specific diameter and specific fiber length and treated with an adhesive in a specific amount. SOLUTION: This composition is obtained by blending (A) 100 pts.wt. rubber component containing a natural rubber and a diene-based synthetic rubber as main components [e.g. a rubber component prepared by blending 100 pts.wt. blend rubber consisting of 50-80 pts.wt. natural rubber and 20 50 pts.wt. polybutadiene rubber with 40-85 pts.wt. carbon black, if necessary, further, 10-30 pts.wt. hydrophilic inorganic reinforcing agent such as white carbon or silane modified clay] with (B) 3-20 pts.wt. synthetic fiber treated with an adhesive treating liquid comprising a resorcine-formaldehyde latex, etc., having 150-400μm diameter and 2-10mm fiber length (e.g. polyamide, polyester or polyvinyl alcohol).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tread rubber composition for a studless tire capable of improving braking performance on a frozen road surface and on snow.

[0002]

2. Description of the Related Art Conventionally, spike tires and tire chains have been used to secure braking performance when a car travels on a frozen road surface or on snow. Also, there is an attempt to improve the braking performance without a stud by improving the tread rubber material. As an example,
Japanese Patent Application Laid-Open No. 60-137946 discloses a tread rubber composition in which alumina having a specific particle size is mixed in rubber, and Japanese Patent Application Laid-Open No. 4-41535 discloses a compound in which a resin having a specific particle size is mixed in rubber. A method for doing so is disclosed.

[0003]

In the conventional methods as described above, the use of spiked tires or tire churn severely damages a dry road surface, and the resulting dust pollution is a major social problem. Improvements in the tread rubber composition disclosed in Japanese Patent Application Laid-Open No. 60-137946 have provided some degree of braking performance, but there have been problems in terms of weight reduction, workability, and cost of the tire. Also, Japanese Patent Application Laid-Open No. 4-41
In the method disclosed in Japanese Patent No. 535, the processability and the dispersibility with rubber are excellent, but the resin is apt to fall off due to the poor adhesion to rubber, and the resin falls off beyond a certain amount. Thus, the spike effect due to scratching disappeared, the braking performance deteriorated, and there was a problem in terms of durability.

The present invention has been made to solve the above problems,
An object of the present invention is to provide a tread rubber composition for a studless tire having excellent braking performance on frozen road surfaces and snow without damaging the road surface, and also having excellent workability, dispersibility, and durability. is there.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve such problems, and as a result, have obtained a synthetic fiber having a specific diameter and a specific fiber length obtained by applying an adhesive treatment to a tread rubber component. By finding that a specific amount of fiber is blended, the present inventors have found that excellent braking performance is exhibited on frozen road surfaces and on snow, and have reached the present invention.

That is, according to the present invention, a rubber component having a diameter of 150 to 400 μm and a fiber length of 2 is treated with 100 parts by weight of a rubber component mainly composed of natural rubber and diene-based synthetic rubber.
The gist of the present invention is a tread rubber composition for a studless tire, characterized in that 3 to 20 parts by weight of a synthetic fiber of 10 to 10 mm is blended.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Examples of the synthetic fibers used in the composition of the present invention include polyamide (nylon), polyester, and polyvinyl alcohol (vinylon).

[0008] In the present invention, the diameter of 150 to
400 μm synthetic fibers are used. Here 150 μm
If it is less than the value, the contact area of the cut fiber on the road surface is small, so that the scratch resistance is small and the braking performance on the frozen road surface is not improved. If it exceeds 400 μm,
The workability and dispersibility of the tread rubber composition are poor, and the decrease in the tensile strength of the processed product is undesirably large.

[0009] The fiber length of the synthetic fiber is 2 to 10 mm.
If the fiber length is less than 2 mm, the workability and dispersibility are good, but the fiber is greatly damaged by friction between the road surface and the tread rubber during running, and there is a problem in the sustainability of braking performance on frozen road surfaces. . If it exceeds 10 mm, the workability and dispersibility of the tread rubber composition are poor, and the decrease in tensile strength of the processed product is undesirably large.

The amount of synthetic fibers in the composition of the present invention is 3 to 20 parts by weight based on 100 parts by weight of a tread rubber component mainly composed of natural rubber and diene-based synthetic rubber.

If the blending amount is less than 3 parts by weight, the scratch resistance is small due to the small contact area of the synthetic fiber on the road surface, and the braking performance on the frozen road surface is not improved. 2
If the amount exceeds 0 parts by weight, the processability during kneading with a Banbury mixer or a roll is significantly reduced. Further, the hardness of the rubber becomes hard, and the braking performance on the frozen road surface is not improved, which is not preferable.

The synthetic fiber of the present invention requires an adhesive treatment. The adhesive may be water-based or solvent-based. Although not particularly limited, an aqueous adhesive treatment is preferred from the viewpoint of cost and workability. Here, as the water-based adhesive, Rs made of resorcinol / formaldehyde / latex used for bonding between fiber and rubber is usually used.
・ Co-condensation product consisting of ethylene urea compound or parachlorophenol and resorcinol / formaldehyde in FL / L treatment liquid or R / F / L treatment liquid [Product name: Denabond (Nagase Kasei Kogyo Co., Ltd.) or Vulkabond (ICI Japan) (Manufactured by Co., Ltd.)), but the present invention is not limited thereto.

[0013] In the process of treating the adhesive, after applying the adhesive in the state of synthetic fiber, heat treatment may be performed and then cut to a predetermined length, or cut to a predetermined length before bonding. An agent may be applied and heat treatment may be performed, and there is no particular limitation. The amount of adhesive attached to the synthetic fiber is
The range of 1 to 7% is preferable from the viewpoints of adhesiveness and cost.

The tread rubber component in the present invention is mainly composed of natural rubber and diene-based synthetic rubber, and it is desirable to use a rubber having good low-temperature characteristics. Diene-based synthetic rubbers include polybutadiene rubber, polystyrene,
There are polybutadiene copolymer rubber, butadiene / acrylonitrile copolymer rubber, isoprene rubber, chloroprene rubber and the like. The weight ratio of natural rubber to diene-based synthetic rubber is preferably from 80:20 to 50:50.

The typical compositions of the present invention are as follows. 40-85 parts by weight of carbon black is blended with 100 parts by weight of a blend rubber composed of 50-80 parts by weight of natural rubber and 20-50 parts by weight of polybutadiene rubber,
Depending on the case, 10 to 30 parts by weight of a hydrophilic inorganic reinforcing agent such as white carbon or silane-modified clay may be added.

In addition, additives usually used in the rubber processing industry are added in usual amounts. For example, 2 to 6 parts by weight of zinc oxide, 1 to 3 parts by weight of stearic acid to 100 parts by weight of the blended rubber
Parts by weight, process oil 20 to 50 parts by weight, sulfur 1.5
To 3.5 parts by weight, a vulcanization accelerator of 0.5 to 2.5 parts by weight, an antioxidant and a wax of 1 to 3 parts by weight, a pigment, an adhesion improver and the like.

The tread rubber component thus obtained is subjected to an adhesive treatment, mixed with the cut synthetic fiber, and kneaded using a Banbury mixer, a roll, or the like, whereby the studless tire of the present invention is obtained. A tread rubber composition can be obtained.

[0018]

According to the present invention, a specific amount of synthetic fibers having a specific fiber length and a specific fiber length obtained by applying an adhesive treatment to a tread rubber component is blended, the synthetic fibers can be dispersed without impairing processability. The excellent adhesion between the rubber component and the synthetic fiber makes it difficult for the fiber to fall off. When used in the tread of a tire, the compounded synthetic fiber becomes a projection, and the contact area with the road surface is large, so the scratch resistance becomes large, and the spike tire It performs the same function as the spikes, and can improve braking performance on icy roads and snow. Further, even if the fibers on the surface fall off, a tread rubber composition which appears one after another with the wear of the tread can be obtained, and can be applied to a studless tire.

[0019]

Next, the present invention will be described in detail with reference to examples. Parts in the examples indicate parts by weight, and the evaluation method is as follows.

(1) Hardness and tensile strength of rubber Measured according to JIS K6301.

(2) Abrasion index The pico abrasion measured according to ASTM 2228 is indicated by an index with 100 when no synthetic fiber is blended. The larger the index, the better the wear resistance.

(3) Friction on Ice The coefficient of friction on ice measured on ice at −10 ° C. using a portable skid tester is shown as an index with 100 when no synthetic fiber is blended. The larger the value, the larger the coefficient of friction and the better the braking performance.

(4) Processability and Dispersibility The processability and dispersibility of the tread rubber composition at the time of kneading with a Banbury mixer and a roll were evaluated as ，: good, ×: poor.

Example 1 Vinylon having a diameter of 233 μm was impregnated with a 6% R / F / L solution composed of resorcinol / formaldehyde / latex, and then subjected to a heat treatment at 170 ° C. for 60 seconds at a total stretch of + 3%, and a resin adhesion amount. A 1.6% vinylon adhesive-treated yarn was obtained, and then cut to a fiber length of 3 mm with a rotary cutter.

70 parts of natural rubber and polybutadiene rubber 30
10 parts of the obtained vinylon cut fiber and 80 parts of carbon black (N339), 6 parts of zinc white, 3 parts of stearic acid, 3 parts of stearic acid, and antioxidant N (100 parts) 1,3-dimethylbutyl) -N'-phenyl-P-phenylenediamine 3 parts, paraffin wax 2 parts, naphthenic oil 40 parts, vulcanization accelerator (MSA) 1
Parts and 2.2 parts of sulfur were blended to obtain a tread rubber composition of Example 1 of the present invention.

Example 2 The tread rubber composition of Example 2 of the present invention was prepared in the same manner as in Example 1 except that the blending amount of the vinylon fiber treated with the adhesive was changed to 3 parts instead of 10 parts. I got something.

Example 3 The tread rubber composition of Example 3 of the present invention was prepared in the same manner as in Example 1 except that the amount of the vinylon fiber treated with the adhesive was changed to 20 parts instead of 3 parts. I got something.

Example 4 After impregnating a 6% -concentration adhesive treatment solution obtained by adding a polyester having a diameter of 320 μm to an R / F / L solution and adding a deabonant at a solid content ratio of 1: 0.3, a stretch of + 1.0% and 80 ° C. Drying for 60 seconds and heat treatment at 240 ° C. for 60 seconds at stretch + 5% were performed to obtain a polyester adhesive-treated yarn having a resin adhesion amount of 1.3%, and then cut to a fiber length of 3 mm with a rotary cutter.

10 parts of the obtained polyester cut fiber was mixed with the same blend rubber as in Example 1 and other additives to obtain a tread rubber composition of Example 4 of the present invention.

Comparative Example 1 In Example 1, the diameter of vinylon used was 233 μm.
A tread rubber composition of Comparative Example 1 was obtained in the same manner as in Example 2, except that m was changed to 128 μm.

Comparative Example 2 In Example 1, the diameter of vinylon used was 233 μm.
A tread rubber composition of Comparative Example 2 was obtained in the same manner as in Example 2 except that m was changed to 467 μm.

Comparative Example 3 The tread rubber composition of Comparative Example 3 was obtained in the same manner as in Example 1 except that the amount of the vinylon fiber treated with the adhesive was changed to 30 parts instead of 10 parts. Was.

Comparative Example 4 A tread rubber composition of Comparative Example 4 was obtained in the same manner as in Example 1, except that the length of the vinylon fiber treated with the adhesive was changed to 1 mm instead of 3 mm.

Comparative Example 5 A tread rubber composition of Comparative Example 5 was obtained in the same manner as in Example 1, except that the length of the vinylon fiber treated with the adhesive was changed to 15 mm instead of 3 mm.

Comparative Example 6 In Example 1, the same blended rubber as in Example 1 and other additives were blended without blending the adhesive-treated vinylon fiber to obtain a comparative example 6 tread rubber composition. .

Table 1 shows the evaluation results of the tread rubber compositions of Examples 1 to 4 and Comparative Examples 1 to 6.

[0037]

[Table 1]

As is clear from Table 1, the tread rubber compositions of Examples 1 to 4 of the present invention have excellent workability and dispersibility, little decrease in tensile strength, good abrasion resistance, and It is recognized that the braking performance on ice is sufficiently maintained.

On the other hand, the tread rubber composition of Comparative Example 1 has no problem in workability and dispersibility, but has poor abrasion resistance and does not show improvement in braking performance on ice. The tread rubber compositions of Comparative Examples 2 and 3 have improved braking performance on ice, but have a reduced tensile strength and poor abrasion resistance. In addition, workability and dispersibility become problems, and it is difficult to operate industrially. The tread rubber composition of Comparative Example 4 has good workability and dispersibility, tensile strength, and abrasion resistance without any problem, but does not show improvement in braking performance on ice. The tread rubber composition of Comparative Example 5 has a slight improvement in braking performance on ice, but has poor workability and dispersibility, and is difficult to operate industrially.

[0040]

The tread rubber composition of the present invention is excellent in processability and dispersibility and has good adhesiveness. When this is used for the tread portion of a tire, synthetic fibers treated with an adhesive become protrusions. As a result, the tread has a function similar to that of a spike, maintains braking performance on a frozen road surface and on snow, and can obtain a tread with good wear resistance, and can be applied to a studless tire.

Claims (1)

[Claims] 1. An adhesive-treated synthetic fiber having a diameter of 150 to 400 μm and a fiber length of 2 to 10 mm is used in an amount of 3 to 20 parts by weight based on 100 parts by weight of a rubber component mainly composed of natural rubber and a diene-based synthetic rubber. A tread rubber composition for a studless tire, characterized by being compounded.