JP2000191839A - Rubber composition for tire tread - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain both decrease of rolling resistance and improvement of wet grip properties by admixing an N-alkenylamide compound with a rubber component. SOLUTION: With 100 pts.wt. of a rubber component such as a styrene- butadiene copolymer rubber(SBR) alone, a blend of the SBR with a natural rubber, a butadiene rubber or an isoprene rubber, and the like is admixed 1-10 pts.wt. of an alkenylamide compound represented by the formula (wherein R1 and R2 are each H or alkenyl and at least one of them is alkenyl) to obtain a rubber composition for a tire tread. As the alkenylamide compound can be exemplified N-allylbenzamide, N,N-diallylbenzamide, N-octadecenylbenzamide, N,N-dioctadecenylbenzamide, N-oleylbenzamide and the like. Into this rubber composition can be incorporated carbon black as a reinforcing agent, inorganic fillers such as silica, clay and the like, and other ingredients as required.

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 which achieves both a reduction in rolling resistance and an improvement in wet grip.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for performance of tires. In particular, improvement in grip performance related to safety and reduction in rolling resistance related to low fuel consumption have received the most attention. Is an issue.

[0003] However, improvement in grip performance and reduction in rolling resistance are contradictory performances, and it is difficult to improve one or the other remaining without deteriorating the performance. .

In order to improve grip performance, it has been proposed to incorporate N-alkylamides and N-phenylamides into a rubber composition (JP-A-4-24955).
No. 1), the tan δ at high temperatures is increased, so that the fuel efficiency is poor, and it is not satisfactory in terms of both improving the grip performance and reducing the rolling resistance.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a rubber composition for a tire tread, in which an N-alkenyl amide compound is added to the rubber composition instead of an N-alkyl amide or N-phenyl amide to reduce rolling resistance. It achieves both improved grip performance, especially on wet road surfaces.

That is, the present invention relates to 100 parts by weight (hereinafter referred to as "parts") of a rubber component, and the general formula (1):

[0007]

Embedded image

The alkenylamide compound 1 represented by the formula (R ₁ and R ₂ are hydrogen atoms or alkenyl groups, and R ₁ and R ₂ may be the same or different, but at least one of them is an alkenyl group) The present invention relates to a rubber composition for a tire tread, which contains 10 to 10 parts.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As the rubber component of the rubber composition for a tire tread of the present invention, a known raw rubber conventionally used for a tire tread can be used without any particular limitation.

Examples of the raw rubber include natural rubber (NR) and styrene-butadiene copolymer rubber (SB).
R), butadiene rubber (BR), ethylene-propylene-diene copolymer rubber (EPDM), isoprene rubber (IR), acrylonitrile-butadiene copolymer rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), And synthetic rubbers such as halogenated butyl rubber (X-IIR). These may be used alone or in combination of two or more. Among these, SBR alone, SBR alone, because of good balance of tire performance such as abrasion resistance, grip performance, and rolling resistance
And NR, BR, and IR are preferred.

In recent years, in particular, SBR having a high styrene content has been preferably used in order to improve the grip performance of a tire. In the present invention, such an SBR having a high styrene content can be used. . The present invention is also effective for SBR having a styrene content of 20 to 50%, for example. The SBR may be of a solution polymerization type or an emulsion polymerization type.

The rubber composition for a tire tread of the present invention has a general formula (1) for achieving both a reduction in rolling resistance and an improvement in grip performance, particularly, an improvement in grip performance on wet road surfaces.

[0013]

Embedded image

The alkenylamide compound represented by (R ₁ and R ₂ are hydrogen atoms or alkenyl groups, and R ₁ and R ₂ may be the same or different, but at least one of them is an alkenyl group) Be blended. Since the alkenylamide compound has an alkenyl group, it is possible to achieve both a reduction in rolling resistance and an improvement in wet grip performance.

The alkenyl group may be linear or branched, but preferably has 3 to 22 carbon atoms from the viewpoint of availability as a compound.

Specific examples of the alkenyl group include, for example, allyl, isopropenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl,
Nonenyl, decenyl, undecenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, eicosenyl, docosenyl, oleyl and the like. Among these, an allyl group, an octadecenyl group, an oleyl group, and the like are preferable because alkenylamine serving as a raw material of the alkenylamide compound is easily available.

Representative examples of the alkenylamide compound include, for example, N-allylbenzamide, N, N-diallylbenzamide, N-octadecenylbenzamide,
N, N-dioctadecenylbenzamide, N-oleylbenzamide and the like can be mentioned.

The amount of the alkenylamide compound to be used is 1 to 10 parts, preferably 3 parts, per 100 parts of the rubber component from the viewpoint of the balance between the effect of the addition and the performance.
~ 8 parts. If the amount is less than 1 part, the effect of adding the alkenylamide compound is not sufficiently obtained, and if the amount is more than 10 parts, the effect of improving the grip performance is reduced, and the burning (scorch) time of the unvulcanized rubber composition is reduced. Since the length is short, molding is difficult, and the cost of compounding increases, which is not practical.

The rubber composition for a tire tread of the present invention may be used alone or as a blend of inorganic fillers such as carbon black, silica and clay commonly used in the rubber industry as reinforcing agents. Good.

Specific examples of the carbon black include:
Examples include, but are not limited to, HAF, ISAF, SAF, and the like.

Examples of the silica include dry-process silica (silicic anhydride) and wet-process silica (hydrous silicic acid). There is no particular limitation, but wet-process silica is preferred. Preferred examples of the wet process silica include Ultrasil VN3 (trade name) manufactured by Degussa Corporation and Nip Seal VN3 AQ (trade name) manufactured by Nippon Silica Co., Ltd.

Examples of the clay include kaolin clay, pyrophyllite clay, sericite clay and calcined clay.

The rubber composition for a tire tread of the present invention may further contain an antioxidant, a vulcanizing agent, a vulcanization accelerator, a vulcanization retarder, a peptizing agent, One or more of auxiliaries, waxes, process oils, stearic acid, tackifiers and the like may be used in combination as needed. When silica is used as a reinforcing agent, a silane coupling agent such as bis (3-triethoxysilylpropyl) tetrasulfide can be used to improve the dispersibility of silica.

The rubber component, an alkenylamide compound,
In general, a rubber composition obtained by blending an inorganic filler and other components as necessary, and using a Banbury mixer, an open roll, or the like, can be suitably used as a rubber composition for a tire tread. . Further, by using the composition for a tire tread,
A tire having both reduced rolling resistance and wet grip properties can be obtained.

[0025]

EXAMPLES Next, the rubber composition for a tire tread of the present invention will be described in more detail with reference to specific examples, but the present invention is not limited thereto.

The raw materials and evaluation methods of the compositions used in the examples and comparative examples are summarized below.

SBR: SBR150 manufactured by Sumitomo Chemical Co., Ltd.
2 BR: BR150B manufactured by Ube Industries, Ltd. NR: General RSS # 3 grade N220: N220 manufactured by Mitsubishi Chemical Corporation N351: N351 manufactured by Showa Cabot Co., Ltd. Zinc oxide: oxidation manufactured by Mitsui Mining & Smelting Co., Ltd. Two kinds of zinc WAX: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. Antioxidant: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd. Process oil: Process X1 manufactured by Japan Energy
40 Sulfur: Powder sulfur manufactured by Karuizawa Sulfur Co., Ltd. Vulcanization accelerator: Noxeller NS manufactured by Ouchi Shinko Chemical Co., Ltd.

(Hardness (Hs)) According to JIS K6253, the tread hardness of a prototype tire was measured with a type A durometer.

When N-alkenyls are blended, the rubber hardness is reduced by simply adding them, so that the process oil and the vulcanizing agent are varied to adjust the tread hardness of each of the examples and comparative examples so as not to vary greatly.

(Wet grip performance (actual vehicle operation stability)) The prototype tire was mounted on an actual vehicle, and on a test course, on a asphalt road surface and on a road surface sprayed with water, the steering stability was evaluated by a sensory evaluation by a test driver. The sex was evaluated. The evaluation indicated the performance by an index. A larger index indicates better performance.

(Rolling resistance (low fuel consumption performance)) Using a testing machine manufactured by Kobe Steel, Ltd., load 345 kg, internal pressure 200
Rolling resistance was measured by running a prototype tire at kPa and a speed of 80 km / h, and the fuel economy performance was indicated by an index.
The higher the index, the lower the rolling resistance and the better.

Examples 1 to 3 and Comparative Examples 1 to 2 The raw materials shown in Table 1 were blended so as to have the composition shown in Table 1, and were prepared by a conventional method using a Banbury mixer and an open roll, that is, Raw materials other than sulfur and the vulcanization accelerator are kneaded with a Banbury mixer at 100 to 150 ° C. for 4 minutes, and then sulfur and the vulcanization accelerator are added at 90 ° C. and kneaded with an open roll for 3 minutes to obtain a green tire tread. A rubber composition was obtained. The reason why the total amount of N-oleylbenzamide and process oil was the same for each blend was to unify the hardness (Hs) of the tread and to exclude the influence of the difference in hardness on other evaluations. . The resulting composition is applied to a tire tread and vulcanized to give 195 /
A tire of 65R15 91H D8H was prototyped by a conventional method.

Using the tires described above, hardness, wet grip performance and rolling resistance were evaluated. Table 1 shows the results.

[0034]

[Table 1]

From the results in Table 1, it can be seen that in Examples 1 to 3 in which N-oleylbenzamide was added, the grip performance and fuel efficiency were all lower than those in Comparative Example 1 in which N-oleylbenzamide was not added. It can be seen that it has improved. In addition, it can be seen that the addition of about 1 to 10 parts has a good balance between the two performances, and that Example 2 in which 5 parts of N-oleylbenzamide is added is most excellent. In Comparative Example 2 in which the addition amount exceeds 10 parts, the fuel economy performance and the wet grip performance are lower than in Example 3.

Examples 4 and 5 and Comparative Examples 3 and 4 A green rubber composition for a tire tread was prepared in the same manner as in Example 1 except that the raw materials shown in Table 2 were blended so as to have the composition shown in Table 2. Was obtained and evaluated in the same manner. The reason why the blending amounts of the process oil and the vulcanization accelerator were changed in each blending is to unify the hardness (Hs) of the tread.

[0037]

[Table 2]

As in the case of Table 1, Examples 4 and 5 to which N-oleylbenzamide was added had improved wet grip performance and low fuel consumption performance as compared with Comparative Example 3.
In the case of Comparative Example 4 where the addition amount is too large, it can be seen that the wet grip performance and the fuel economy performance are not improved.

[0039]

According to the rubber composition for a tire tread of the present invention, a tire having both reduced rolling resistance and wet grip properties can be obtained.

Claims (1)

[Claims] 1. A rubber composition of the general formula (1): (R ₁ and R ₂ are a hydrogen atom or an alkenyl group;
₁ and R ₂ may be the same or different, but at least one of them is an alkenyl group) and a rubber composition for a tire tread containing 1 to 10 parts by weight of an alkenylamide compound represented by the formula (1).