JP2002284928A - Rubber composition for tire tread and tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire tread and a tire using a reclaimed rubber and capable of reducing the heat buildup performances and improving abrasion resistance while maintaining the grip performances. SOLUTION: This rubber composition for the tire tread is characterized by comprising 1-40 pts.wt. of the reclaimed rubber having <=20 wt.% amount of acetone extraction and/or <=10 wt.% amount of chloroform extraction in 100 pts.wt. of a diene rubber component. The tire uses the composition in the tread.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for a tire tread and a tire using the same, and more particularly, to a tire tread capable of lowering heat generation performance and improving abrasion resistance while maintaining grip performance. The present invention relates to a rubber composition for tires and a tire using this composition for a tread.

[0002]

2. Description of the Related Art In recent years, recycling of waste has been strongly demanded from the viewpoint of environmental problems and resource saving. Tires are no exception, and waste tires are used in various applications after various treatments, such as finely pulverizing them with a crusher to remove fibers and steel and reusing them as rubber powder. I have.

[0003] In particular, the so-called material recycling of the recycling type which is reused as a tire is very important and indispensable. A method of recycling a waste tire into recycled rubber or rubber powder and reusing the tire has been known for a long time.
However, the usage amount and usage ratio of the recycled rubber are decreasing year by year because the heat generation performance is increased and the abrasion resistance is greatly reduced.

[0004] Under such circumstances, attempts to improve rubber properties by using a reinforcing filler have been very well known.
Among them, carbon black which imparts high reinforcement and excellent wear resistance is widely used. In order to further improve the wear resistance of the pneumatic tire, it is conceivable to increase the filling amount of carbon black or to use carbon black having a smaller particle diameter. However, in any case, hysteresis loss increases due to carbon black, and heat generation performance increases.

On the other hand, hydrated silicic acid is known as a filler satisfying both heat generation performance, grip performance and abrasion resistance. However, hydrous silicic acid has a lower storage modulus of the rubber composition as compared with carbon black having the same specific surface area, and therefore has poor grip performance. As a method of increasing the storage elastic modulus, an increase in the amount of hydrous silicic acid or an increase in the specific surface area can be considered.

Various proposals have been made in the past to solve these problems. However, at present, there is no rubber composition having a highly balanced grip performance, heat generation performance and abrasion resistance. is there.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a tire tread which uses recycled rubber in such a situation and can reduce heat generation while maintaining grip performance and improve abrasion resistance. An object of the present invention is to provide a rubber composition and a tire using the composition for a tread.

[0008]

In order to solve the above-mentioned problems, a study was conducted to find that the amount of acetone extracted was 20% by weight.
By adding a reclaimed rubber having an extraction amount of not more than 10% by weight or less, the heat generation performance is reduced while maintaining the grip performance, and the abrasion resistance is improved as compared with a conventional tire containing the reclaimed rubber. I found that it could be done.

That is, the present invention provides a diene rubber component 10
A rubber composition for a tire tread, comprising 1 to 40 parts by weight of a recycled rubber having an acetone extraction amount of 20% by weight or less and / or a chloroform extraction amount of 10% by weight or less based on 0 part by weight. .

The present invention also relates to a tire using the above rubber composition for a tread.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber composition of the present invention contains a specific reclaimed rubber, thereby lowering heat generation performance and improving abrasion resistance while maintaining grip performance. If the heat generation performance is reduced, energy loss is reduced and rolling resistance is reduced, so that fuel efficiency can be reduced.

The recycled rubber is not particularly limited as long as it is recycled from a generally used rubber product or the like. Methods for producing recycled rubber, including the most common bread method (oil method), a method using a Banbury mixer and a twin-screw extruder, a method using microwaves, a method using ultrasonic waves, and a method using electron beam irradiation have been developed. However, it may be reproduced by any method.

The recycled rubber used in the present invention has an acetone extraction of 20% or less and / or chloroform extraction of 10% by weight or less. 20% acetone extraction
If the amount of chloroform exceeds 10% by weight, and the amount of chloroform exceeds 10% by weight, the heat generation performance increases and the wear resistance decreases. Further, it is preferable that the extraction amount of acetone is 15% by weight or less and the extraction amount of chloroform is 5% by weight or less.

Here, the acetone extraction amount and chloroform extraction amount of the reclaimed rubber can be determined by the following method.

Approximately 2 g of the recycled rubber is weighed correctly to 1 mg and wrapped in filter paper or placed in a cylindrical filter paper, which is placed in a sign cup of a Knefrelle-type or cottle-type extraction device, and a pre-measured extraction. About 50 ml of the extract (acetone or chloroform) is placed in the flask, and the entire apparatus is assembled and extraction is performed while heating. Heating is adjusted so that the extract in the siphon cup drops and renews about every 3 minutes, and the extraction time is 48 hours continuous.

After the extraction, the extract is heated on a water bath, and after the extract is distilled off, immediately dried in an air bath at 70 ± 5 ° C. for about 2 hours, allowed to cool, weighed, and weighed. Acetone extraction or chloroform extraction.

The components contained in the extract obtained by acetone extraction and chloroform extraction are mainly composed of free sulfur,
Regenerated rubber containing a softener, a swelling agent, a low molecular weight component generated at the time of regeneration, and a large amount of these components increases heat generation performance and lowers abrasion resistance.

The content of the recycled rubber is 1 to 40 parts by weight, preferably 1 to 30 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the diene rubber described below. If the content exceeds 40 parts by weight, the heat generation performance increases, and the wear resistance decreases.

As the diene rubber, natural rubber and / or diene synthetic rubber is used. Here, as the diene-based synthetic rubber, for example, styrene-butadiene rubber (SBR), isoprene synthetic rubber (IR), acrylonitrile-butadiene rubber (NBR), isobutylene-isoprene rubber (IIR), chloroprene rubber (C
R) and the like. These rubbers may be used alone or in combination of two or more.

Further, the rubber composition of the present invention preferably contains a reinforcing filler. As a filler for reinforcement,
Although it can be arbitrarily selected from those commonly used in conventional rubber compositions for tires, carbon black and silica particles are mainly preferred.

The upper limit of the nitrogen adsorption specific surface area of the carbon black is preferably 280 m ² / g, particularly preferably 200 m ² / g. Nitrogen adsorption specific surface area is 280m ²
/ G tends to increase heat generation performance. The lower limit is preferably 80 m ² / g, particularly preferably 100 m ² / g. Nitrogen adsorption specific surface area of carbon black is 80
If it is less than m ² / g, the abrasion resistance tends to decrease.

The content of the carbon black is 10 to 150 parts by weight based on 100 parts by weight of the diene rubber component.
In particular, it is preferably 15 to 100 parts by weight. If the content of carbon black is less than 10 parts by weight, abrasion resistance tends to decrease, and if it exceeds 150 parts by weight, heat generation performance tends to increase.

The silica has a nitrogen adsorption specific surface area of 100.
It is preferably from 〜280 m ² / g. When the nitrogen adsorption specific surface area of silica is less than 100 m ² / g, abrasion resistance tends to decrease, and when it exceeds 280 m ² / g, heat generation performance tends to increase.

The reinforcing filler may be used alone,
Two or more kinds may be used in combination.

The rubber composition of the present invention may further contain, in addition to the above components, various chemicals usually used in the rubber industry, for example, a vulcanizing agent such as sulfur, various vulcanization accelerators, various softening agents, Additives such as antioxidants, zinc oxide, stearic acid, antioxidants, and antiozonants can be added.

The tire of the present invention is produced by a usual method using the rubber composition of the present invention. That is, if necessary, the rubber composition of the present invention containing the various chemicals is extruded in accordance with the shape of the tire tread in an unvulcanized stage, and molded by a usual method on a tire molding machine. Form a vulcanized tire. The unvulcanized tire is heated and pressed in a vulcanizer to obtain a tire. The tire of the present invention thus obtained is excellent in balance between heat generation performance and wear resistance.

[0027]

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

Example 1 and Comparative Examples 1-2 According to the compounding recipe shown in Table 1, kneading and compounding were carried out to obtain various test rubber compositions. These formulations were added at 170 ° C for 2
Vulcanized products were obtained by press vulcanization for 0 minutes, and these were tested for the following properties.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described. Natural rubber: RSS # 3 manufactured by Tech Bee Hang Co. SBR: SBR1502 manufactured by JSR Co., Ltd. Carbon black: Show black N220 manufactured by Showa Cabot Co., Ltd. (nitrogen adsorption specific surface area 125 m ² / g) Recycled rubber: commercially available Rubber powder (Muraoka Rubber Industries Co., Ltd.
-2A) was produced by subjecting 60 cc of a Labo Plastomill controlled at 180 ° C. to shearing for 10 minutes and desulfurizing (extracting acetone 12.1%, extracting chloroform 4.2%) recycled rubber: Muraoka Rubber Recycled rubber R-50 manufactured by Kogyo Co., Ltd.
0 (20.2% acetone extraction, 1 chloroform extraction)
0.1%) Antioxidant: Nocrack 6 manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) Stearic acid: Stearic acid manufactured by NOF CORPORATION Zinc oxide: Zinc flower No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: powder sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator: Noxeller C manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Z

Hereinafter, a method for evaluating a vulcanized rubber will be described. (1) Grip performance Size 19 having a tread made of the above rubber composition
A 5 / 65R15 tire was produced. Using these tires, an actual vehicle was run on a test course on dry asphalt road surface. The test driver evaluated the stability of the control at the time of steering. The larger the value, the higher the grip performance on dry road surfaces.

(2) Heat generation performance Using a spectrometer manufactured by Ueshima Seisakusho, ta was measured under the conditions of a dynamic strain amplitude of 2%, a frequency of 10 Hz and a temperature of 70 ° C.
nδ was measured. The reciprocal of the value of tan δ was represented as an index with the case of Comparative Example 1 as 100. The larger the numerical value, the lower the heat generation performance and the better.

(3) Abrasion resistance Using a Lambourn abrasion tester, room temperature, applied load 1.
The wear amount was measured under the conditions of 0 kgf, a slip rate of 30%, and a test time of 5 minutes. The reciprocal of the amount of wear was 10 for Comparative Example 1.
The index was indicated as 0. The larger the value, the higher the wear resistance.

The results are shown in Table 1. As is clear from Table 1, in Example 1 using an appropriate amount of recycled rubber, Comparative Example 1,
As compared with No. 2, the heat generation performance was reduced and the wear resistance was improved without lowering the grip performance.

[0034]

[Table 1]

[0035]

According to the present invention, it is possible to provide a tire having reduced heat generation performance and greatly improved wear resistance while maintaining grip performance by using recycled rubber.

Claims (2)

[Claims] 1. A recycled rubber having an acetone extraction of 20% by weight or less and / or a chloroform extraction of 10% by weight or less with respect to 100 parts by weight of a diene rubber component.
A rubber composition for a tire tread, which is contained in an amount of 40 to 40 parts by weight. 2. A tire using the rubber composition according to claim 1 for a tread.