JP2004010863A - Rubber composition for tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for tire excellent in the high-order balance between braking performance and LRR (low rolling resistance). <P>SOLUTION: The rubber composition is prepared by compounding 100 pts.wt. diene rubber with at least two pts.wt. EPDM (ethylene-propylene-diene terpolymer) of which the third component is 5-ethylidene-2-norbornene (ENB) having an iodine value of 100 or higher and which has a Tg of -25°C or higher. <P>COPYRIGHT: (C)2004,JPO

Description

（註）＊１：ＥＰＤＭの種類を以下の表２に示す。
＊２：ダイアブラック　Ｎ３３９（三菱化学製）
＊３：アンチゲン　６Ｃ（住友化学製）
＊４：ノクセラー　ＣＺ（大内新興化学製）
【００１６】
【表２】

（註）＊１：Ｔｇは、ｔａｎδのピーク温度により測定。
【００１７】
【発明の効果】
本発明によるタイヤ用ゴム組成物は、以上の結果からみて、ウェット制動の指標であるｔａｎδ（０℃）が約１０％向上し、ドライ制動の指標であるｔａｎδ（２０℃）が約５０％向上し、更に、ころがりの指標であるｔａｎδ（６０℃）は、同等〜約５％低減することがみられ、本発明の目的である制動性能とＬＲＲ性能の高次のバランスが図られている。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rubber composition for a tire, and more particularly, to a rubber composition for a tire that achieves a balance between a braking performance and a low rolling resistance (LRR) performance.
[0002]
[Prior art]
Conventionally, as a performance required for a tire, a balance ratio between a braking performance and a low rolling resistance (LRR) performance is required. In general, when a rubber such as butyl-based or EPDM (ethylene-propylene-diene terpolymer) is blended, the braking performance is improved, but these types of rubbers are copolymerized with a diene-based rubber such as SBR. vulcanizable is or becomes slow vulcanization rate for bad, also, there is a problem that the S-S characteristics _(modulus, T B, _{E B)} is lowered significantly.
[0003]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a rubber composition for a tire in which both the braking performance and the LRR performance are simultaneously improved.
[0004]
[Means for Solving the Problems]
According to the present invention, the iodine value of 5-ethylidene-2-norbornene (ENB), which is the third component of ethylene-propylene-diene terpolymer (EPDM), is 100 or more per 100 parts by weight of diene rubber. Provided is a rubber composition for a tire, which contains 2 parts by weight or more of an EPDM having an EPDM polymer having a Tg of −25 ° C. or more.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventor intends to balance the braking performance and the LRR performance as the above-mentioned tire performance to a high order by increasing the content of the third component (diene) of the conventional EPDM to an extremely high level. By synthesizing a novel EPDM having a high Tg and blending it with a diene rubber, it was found that tan δ can be significantly improved in a temperature range of about −10 to + 40 ° C., which affects grip performance, The present invention has been reached.
[0006]
The specific EPDM polymer used in the present invention can be easily obtained by a synthesis method by adding, for example, ethylene and propylene monomers and a vanadium catalyst, and adding and copolymerizing 5-ethylidene-2-norbornene (ENB) as a third component. I can do it.
[0007]
Unless the iodine value of ENB, which is the third component of the EPDM polymer, is not at least 100, the polymer Tg cannot be increased, the number of crosslinking points decreases, and the co-vulcanizability decreases. Has an iodine value of 100 to 250, more preferably 100 to 200. Further, if the Tg of EPDM is less than -25 ° C, it is not preferable in that the tan δ of about -10 to 40 ° C, which is an index of grip, decreases, and the Tg is usually -25 ° C to 40 ° C, preferably- A temperature of 15 ° C. to 30 ° C. is suitable for achieving a higher-order balance between the braking performance and the LRR performance.
[0008]
The EPDM polymer is used in an amount of 2 parts by weight or more based on the diene rubber in the rubber composition for a tire of the present invention. If the blending amount of EPDM is less than 2 parts by weight, the desired effect cannot be obtained. In order to obtain better mechanical properties and abrasion resistance, the amount is preferably 2 to 30 parts by weight.
[0009]
Examples of the diene rubber used in the tire rubber composition of the present invention include natural rubber (NR), polyisoprene rubber (IR), various styrene-butadiene copolymer rubbers (SBR), various polybutadiene rubbers (BR), Diene rubbers such as acrylonitrile-butadiene copolymer rubber (NBR) and butyl rubber (IIR) can be used alone or as an arbitrary blend.
[0010]
In the tire rubber composition of the present invention, in addition to the above-mentioned essential components, carbon black, reinforcing agents such as silica, vulcanization, cross-linking agent, vulcanization, cross-linking accelerator, various oils, anti-aging agent, plasticizer And various additives commonly used for other tires can be compounded, and the compound is kneaded and vulcanized into a composition by a general method and used for vulcanization or crosslinking. can do. The amounts of these additives may be conventional general amounts as long as the object of the present invention is not adversely affected.
[0011]
【Example】
Hereinafter, the present invention will be further described with reference to Examples, but it goes without saying that the scope of the present invention is not limited to these Examples.
[0012]
Examples 1-4 and Comparative Examples 1-5
In the formulation (parts by weight) shown in Table 1 below, the vulcanization accelerator and the components excluding sulfur were kneaded for 3 to 5 minutes in a 1.8 L closed mixer, and the master was released when the temperature reached 165 ± 5 ° C. The batch was kneaded with a vulcanization accelerator and sulfur with an 8-inch open roll to obtain a rubber composition. The obtained rubber composition was vulcanized at 160 ° C. for 10 minutes to prepare various test pieces, which were subjected to the following tests.
[0013]
1) tanδ
Using a viscoelastic spectrometer (manufactured by Toyo Seiki Co., Ltd.), the temperature was measured at 0 ° C., 20 ° C., and 60 ° C. under the conditions of initial strain: 10%, dynamic strain: ± 2%, and frequency: 20 Hz, respectively. Comparative Example 1 was set to 100 and an index was displayed. The higher the tan δ value at 0 ° C. and 20 ° C., the better the braking performance, and the lower the tan δ value at 60 ° C., the better the rolling performance.
[0014]
2) Tensile test (SS characteristics)
Conforming to JIS6251 measured tensile stress at break _{T B} and was an exponential display as Comparative Example 1 being 100. The higher the value, the better.
[0015]
The results are shown below.
[Table 1]

(Note) * 1: The types of EPDM are shown in Table 2 below.
* 2: Diablack N339 (Mitsubishi Chemical)
* 3: Antigen 6C (Sumitomo Chemical)
* 4: Noxeller CZ (Ouchi Shinko Chemical)
[0016]
[Table 2]

(Note) * 1: Tg is measured by the peak temperature of tan δ.
[0017]
【The invention's effect】
In view of the above results, the rubber composition for a tire according to the present invention improves tan δ (0 ° C.) which is an index of wet braking by about 10%, and improves tan δ (20 ° C.) which is an index of dry braking by about 50%. Further, tan δ (60 ° C.), which is an index of rolling, is seen to be reduced by an equivalent to about 5%, and a high-order balance between the braking performance and the LRR performance, which is the object of the present invention, is achieved.

Claims (1)

In 100 parts by weight of a diene rubber, EPDM in which the iodine value of 5-ethylidene-2-norbornene (ENB), which is the third component of ethylene-propylene-diene terpolymer (EPDM), is 100 or more, and Tg is A rubber composition for a tire, containing at least 2 parts by weight of an EPDM polymer at -25 ° C or higher.