JP2007321093A - Rubber composition for tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for tire having improved abrasion resistance and braking performance on wet road and on ice in balanced state. <P>SOLUTION: The rubber composition for tire comprises (A) a diene rubber composed of 20-80 wt.% natural rubber and/or polyisoprene rubber and 80-20 wt.% butadiene rubber and (B) 1-50 pts.wt. of a terpene resin based on 100 pts.wt. of the diene rubber A, wherein the terpene resin has a glass transition temperature of ≤-10°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rubber composition for a tire excellent in abrasion resistance and braking performance on a wet road surface and on ice, which is formulated with a specific terpene resin having a low environmental load.

  Various plasticizers or softeners for rubber are known, and aromatic oils excellent in compatibility with rubber are generally used. However, the aromatic oil has a problem that the load on the environment is large due to the polycyclic aromatic component contained therein, and various plasticizers or softeners have been proposed to replace the aromatic oil. Yes. For example, by adding a norbornene polymer containing a softener to a natural rubber and / or a diene synthetic rubber and a tackifier, the slip resistance on snow, ice and wet road surfaces after molding and crosslinking is improved. Is described in Patent Document 1, and further, coumarone-indene resin, petroleum hydrocarbon resin, formaldehyde resin, polyterpene resin, rosin ester resin, and the like are described as specific examples of the tackifier. ing. In Patent Document 2, a terpene resin having a melting point of less than 10 ° C. and a number average molecular weight of 200 to 600 is used as a tackifier for 100 parts by weight of a rubber component containing 50% by weight or more of a styrene-butadiene copolymer rubber. It describes that the handling stability and breaking strength are improved by blending parts by weight. Patent Document 3 describes that 10 to 150 parts by weight of a terpene resin is blended with 100 parts by weight of a diene rubber to improve factory workability and grip. However, with the demand for higher performance of tires, further improvements in wear resistance, braking performance on wet road surfaces (hereinafter referred to as “wet braking performance”) and braking performance on ice are strongly desired.

JP-A-11-246711 JP 2005-187634 A JP 2004-18760 A

  Accordingly, an object of the present invention is to improve the wear resistance, wet braking performance and on-ice braking performance in a well-balanced manner when the load on the environment is small and, for example, it is used for manufacturing a tire, particularly a tread member of a tire. The object is to provide a rubber composition for a tire.

  The inventor of the present invention uses a terpene resin having a glass transition temperature (Tg) of −10 ° C. or less as a plasticizer or softener of a rubber composition comprising natural rubber and / or polyisoprene and butadiene rubber as a rubber component. When it mix | blends, it discovered that abrasion resistance, wet braking performance, and the braking performance on ice could be improved further, and came to complete this invention.

According to the present invention,
(A) a diene rubber composed of 20 to 80% by weight of natural rubber and / or polyisoprene rubber and 80 to 20% by weight of butadiene rubber;
(B) 1 to 50 parts by weight of a terpene resin with respect to 100 parts by weight of the diene rubber (A);
A tire rubber composition comprising: a tire rubber composition, wherein the terpene resin has a Tg of -10 ° C or lower.

  Since the tire rubber composition of the present invention comprises a terpene resin that is a plant-derived compound instead of an aromatic oil as a plasticizer or softener, not only has a small impact on the environment, There is also an advantage that the petroleum removal of the tire manufacturing raw material can be promoted.

  The diene rubber (A) used in the tire rubber composition of the present invention comprises, as described above, 20 to 80% by weight of natural rubber and / or polyisoprene rubber and 80 to 20% by weight of butadiene rubber. The natural rubber and / or polyisoprene rubber and butadiene rubber are not particularly limited as long as they are used for the tire rubber composition. If the blending ratio of natural rubber and / or polyisoprene rubber and butadiene rubber is out of the above range, it is not preferable because braking performance on ice and wear resistance are lowered.

  The terpene resin (B) blended in the tire rubber composition of the present invention has a Tg of -10 ° C or lower, preferably -80 ° C to -30 ° C. If Tg exceeds −10 ° C., the hardness at low temperature becomes too high, and the braking performance on ice is not sufficiently improved, which is not preferable. Furthermore, in a preferred embodiment, the terpene resin (B) has a hydroxyl value (OH value) of 20 mgKOH / g or less. If the Tg of the terpene resin (B) is less than −80 ° C., there is a possibility that sufficient reinforcing property as a rubber composition may not be obtained, and if it exceeds −30 ° C., the hardness at low temperature becomes excessively high and braking on ice. This is not preferable because the performance may not be sufficiently improved. When the OH value of the terpene-based resin (B) exceeds 20 mgKOH / g, self-aggregation becomes strong, which may cause problems such as deterioration in fracture characteristics and deterioration of wear resistance. Here, the terpene-based resin means a resin obtained by purifying and polymerizing a series of compounds according to the isoprene rule such as α-pinene, β-pinene and limonene obtained from plants. The terpene resin (B) is blended in the tire rubber composition of the present invention at a ratio of 1 to 50 parts by weight with respect to 100 parts by weight of the diene rubber (A). When the blending amount of the terpene resin (B) exceeds 50 parts by weight with respect to 100 parts by weight of the diene rubber (A), the change in physical properties with time is increased, which is not preferable.

  The braking performance on ice can be further improved by blending the rubber composition for a tire of the present invention with a filler containing an inorganic filler. The blending amount of the filler is 30 to 60 parts by weight per 100 parts by weight of the diene rubber (A). If the blending amount is small, the effect of reinforcing the rubber is small, and conversely if too large, the hardness of the rubber becomes too high and the braking performance on ice becomes low, which is not preferable. The compounding amount of the inorganic filler is 10 to 50 parts by weight, preferably 10 to 45 parts by weight, per 100 parts by weight of the diene rubber (A). When an inorganic filler with an amount in this range is blended, the hardness at low temperatures can be kept low, and the braking performance on ice is improved. Examples of the inorganic filler include silica, calcium carbonate, aluminum hydroxide and the like, and silica is particularly preferably used. Examples of other fillers include carbon black.

  In the tire rubber composition of the present invention, in addition to the components (A) and (B), stearic acid, a vulcanization or crosslinking agent, a vulcanization or crosslinking accelerator, which is generally blended in the rubber composition Various compounding agents such as an anti-aging agent, a plasticizer, and a coupling agent can be blended.

  The rubber composition for tires of the present invention can be produced by a general mixing or kneading method and operating conditions using a mixing or kneading apparatus such as a Banbury mixer or a kneader that is usually used for blending the rubber composition. it can. The rubber composition of the present invention is kneaded with a predetermined amount of the above components and other general compounding agents, or a rubber mixture (master batch) of specific components is prepared in advance and then mixed or kneaded with the predetermined components. Can be manufactured. Since the rubber composition of the present invention is excellent in wear resistance, wet braking performance and on-ice braking performance, it can be used particularly effectively as a tread member of a tire.

  The present invention will be further explained by the following examples and comparative examples, but it goes without saying that the scope of the present invention is not limited to these examples.

Preparation of Rubber Compositions of Comparative Examples 1 to 4 and Examples 1 to 3 According to the composition (parts by weight) shown in Table 1 below, using a 1.8 liter closed Banbury mixer, 4 to The mixture was mixed for 5 minutes, discharged from the mixer at 150 ± 5 ° C., and then cooled to room temperature. Then, the vulcanization accelerator and sulfur were mixed with an open roll to obtain rubber compositions of Comparative Examples 1 to 4 and Examples 1 to 3.

註 in Table 1:
1) STR20
2) Nipol BR1220 (manufactured by Nippon Zeon Co., Ltd.)
3) Show Black N220 (manufactured by Showa Cabot Corporation)
4) Nip seal AQ (manufactured by Tosoh Silica Co., Ltd.)
5) Three types of zinc oxide (manufactured by Shodo Chemical Industry Co., Ltd.)
6) Bead stearic acid paulownia (manufactured by NOF Corporation)
7) Ozonon 6C (Seiko Chemical Co., Ltd.)
8) Si69 (manufactured by Degussa AG)
9) Noxeller CZ-G (Ouchi Shinsei Chemical Co., Ltd.)
10) Sunceller DG (manufactured by Sanshin Chemical Industry Co., Ltd.)
11) Fine powder sulfur with Jinhua seal oil (manufactured by Tsurumi Chemical Co., Ltd.)
12) Process X-140 (manufactured by Japan Energy Co., Ltd.)
13) Cosmo Neutral 150 (manufactured by Cosmo Oil Co., Ltd.)
14) YS Polystar U115 (manufactured by Yasuhara Chemical Co., Ltd.): hydroxyl value = 30 mgKOH / g, Tg = 65 ° C.
15) YS resin PX # 200 (manufactured by Yasuhara Chemical Co., Ltd.): hydroxyl value = 2.4 mgKOH / g, Tg = −53 ° C.
16) YS resin LP (manufactured by Yasuhara Chemical Co., Ltd.): hydroxyl value = 1.3 mgKOH / g, Tg = −63 ° C.
17) Dimaron (manufactured by Yasuhara Chemical Co., Ltd.): hydroxyl value = 3.4 mgKOH / g, Tg = −50 ° C.
18) YS resin PX800 (manufactured by Yasuhara Chemical Co., Ltd.): hydroxyl value = 3 mgKOH / g, Tg = 30 ° C.

Test Method 1) Abrasion Resistance The above-mentioned unvulcanized rubber composition was vulcanized at 160 ° C. for 20 minutes in a mold, and then a lamborn abrasion test was performed according to JIS K6264. The test piece surface rotation speed was 80 m / min, the applied load was 15 N, and the slip ratio was 50%. The results are expressed as relative values when the wear volume of Comparative Example 1 is taken as 100. The larger the value, the better the wear resistance.

2) Wet braking performance The above-mentioned unvulcanized rubber composition was made into a rubber sheet having a thickness of 2 mm and vulcanized at 160 ° C for 20 minutes. The obtained vulcanized rubber sheet was subjected to wet braking performance under the conditions of a measurement temperature of 0 ° C., a frequency of 20 Hz, and a strain rate of 0.5% using a rheometric viscoelasticity tester (type RDS-2). Loss tangent tan δ was measured as an index. The larger the tan δ at 0 ° C., the better the wet braking performance. The result was expressed as a relative value when the value of tan δ of Comparative Example 1 was 100. The larger the value, the better the wet braking performance.

3) Braking performance on ice The above-mentioned unvulcanized rubber composition was press-heated in a 15 cm × 15 cm × 0.2 cm mold at 160 ° C. for 20 minutes to prepare a test piece. The friction coefficient on ice was obtained as an index of braking performance on ice using an inside drum type on-ice friction tester, which was affixed to rubber, at a temperature of -1.5 ° C, a load of 0.54 MPa, and a drum rotation speed of 25 km / h. . The results are expressed as relative values when the friction coefficient on ice of Comparative Example 1 is 100. The larger the value, the better the braking performance on ice.

  From the results of Table 2, it can be seen that when the specific terpene resin is blended with the diene rubber in the predetermined amount, the wear resistance, wet braking performance and on-ice braking performance are improved in a well-balanced manner.

Claims (3)

(A) a diene rubber composed of 20 to 80% by weight of natural rubber and / or polyisoprene rubber and 80 to 20% by weight of butadiene rubber;
(B) 1 to 50 parts by weight of a terpene resin with respect to 100 parts by weight of the diene rubber (A);
A rubber composition for tires, wherein the terpene resin has a glass transition temperature of −10 ° C. or lower.   2. The tire rubber composition according to claim 1, wherein the terpene resin (B) has a hydroxyl value of 20 mg KOH / g or less and a glass transition temperature of −80 ° C. to −30 ° C. 3.   The rubber composition contains 30 to 60 parts by weight of a filler with respect to 100 parts by weight of the diene rubber (A), and 10 to 50 parts by weight of the filler is an inorganic filler. The rubber composition for tires according to claim 1 or 2.