JP6147618B2 - Rubber composition and pneumatic tire - Google Patents

Description

  The present invention relates to a rubber composition and a pneumatic tire using the same.

  In various rubber compositions typified by tire rubber compositions, it is desired to improve wear resistance performance without deteriorating various physical properties.

  For such a purpose, for example, Patent Document 1 describes that the addition of polybutene end-modified with maleic anhydride improves the wear resistance and the processability of the rubber composition.

  Patent Document 2 describes that by adding a compound containing a maleic acid structure and a specific silane compound, the dispersibility of silica is improved and the workability is improved without lowering the wear resistance. Has been.

  Although these rubber compositions of Patent Documents 1 and 2 have a certain effect in improving wear resistance or suppressing deterioration, there is a need for a new improver that can achieve an effect equal to or higher than that.

  On the other hand, maleic acid-based copolymers have been conventionally used as dispersants, binders, and resin modifiers. For example, Patent Document 3 discloses the impact resistance and rigidity of molded products as additives for polycarbonate resin compositions. It is described that can be improved. Further, as a rubber modifier, for example, by adding an alkylene-maleic anhydride resin and / or an alkylene-maleic anhydride resin to Patent Document 4, the wet performance of the tire is improved by the water absorption of these resins. It is disclosed that it is possible. However, these documents do not describe improvement of the wear resistance of rubber using a maleic acid copolymer.

JP 11-35735 A JP 2005-232354 A JP-A-8-188708 JP 11-323023 A

  This invention is made | formed in view of the above, and provides the rubber composition which improved the abrasion resistance performance of rubber | gum by using a specific maleic acid type copolymer, and a pneumatic tire using the same. For the purpose.

In order to solve the above-mentioned problems, the rubber composition for tires of the present invention comprises an α-olefin represented by the following general formula (1) and maleic anhydride with respect to 100 parts by mass of the diene rubber component. It shall contain 0.5-20 mass parts of copolymer and 10-150 mass parts of reinforcing filler.

  In the formula, R represents a linear or branched alkyl group having 20 to 70 carbon atoms, and n represents an integer of 1 or more.

The tire rubber composition of the present invention may contain 15% by mass or more of the amino group-containing modified diene rubber in the diene rubber component.

The pneumatic tire of the present invention is formed using the tire rubber composition of the present invention.

  According to the rubber composition of the present invention, a rubber having improved wear resistance can be obtained by using a copolymer of an α-olefin represented by formula (1) and maleic anhydride. This is considered to be due to the fact that the copolymer represented by the formula (1) has a long-chain alkyl group having 20 or more carbon atoms in the side chain, thereby improving the dispersibility of the reinforcing filler.

  In addition, when an amino group-containing modified diene rubber is used in a certain amount or more as a rubber component, the wear resistance can be further improved.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

  Examples of the diene rubber that can be used in the present invention include various natural rubbers (NR), various polyisoprene rubbers (IR), various styrene butadiene rubbers (SBR), various polybutadiene rubbers (BR), etc. One kind may be used, or two or more kinds may be used in combination. Preferably, styrene butadiene rubber and various polybutadiene rubbers are used.

  In addition, as these rubbers, modified diene rubbers introduced with amino groups, alkoxysilane groups, hydroxy groups, epoxy groups, carboxyl groups, cyano groups, halogens, etc. can be used as necessary, for example, modified solution polymerized styrene butadiene. Rubber (modified S-SBR) is preferably used.

  In particular, by containing a certain amount or more of a modified diene rubber having an amino group in the diene rubber component, the wear resistance of the rubber can be further improved. The content of the amino group-containing modified diene rubber is preferably 15% by mass or more, more preferably 30% by mass or more, and particularly preferably 50% by mass or more. This is considered to be due to the reaction with the amino group of the modified diene rubber because the maleic anhydride equivalent portion of the copolymer represented by the formula (1) described below has reactivity with the amino group.

A copolymer of α-olefin and maleic anhydride used in the present invention (hereinafter sometimes simply referred to as a copolymer) has a structure represented by the following general formula (1).

  In the above formula (1), R represents a linear or branched alkyl group, and the carbon number is preferably in the range of 20 to 70, more preferably 30 to 60, from the viewpoint of excellent target wear resistance improvement effect. Further, the number of repeating units n is preferably 1 or more, more preferably 3 or more, and particularly preferably 3 to 30 from the viewpoint of improving wear resistance. The copolymer represented by the formula (1) can be used alone, or a mixture of two or more different R and / or n can be used.

  The copolymer of α-olefin and maleic anhydride can be synthesized according to a known method, and a commercially available one can be used as appropriate. Examples of commercially available products include “Diacarna 30” (trade name) manufactured by Mitsubishi Chemical Corporation.

  The content of the copolymer of α-olefin and maleic anhydride is preferably in the range of 0.5 to 20 parts by mass with respect to 100 parts by mass of the diene rubber component from the viewpoint of the effect of improving wear resistance. The range of -10 is more preferable.

  Next, as the reinforcing filler used in the present invention, those usually used in the rubber field can be used without particular limitation, and examples thereof include carbon black, silica, talc, clay, aluminum hydroxide, titanium oxide and the like. In general, carbon black and / or silica are preferably used.

  The content of the reinforcing filler is appropriately adjusted depending on the use of the rubber composition, but is usually preferably in the range of 5 to 150 parts by weight with respect to 100 parts by weight of the diene rubber component, 120 mass parts is more preferable, and 50-100 mass parts is especially preferable. When carbon black is used, the range of 5 to 120 parts by mass is usually preferred per 100 parts by mass of the rubber component, and when silica is used, the range of 5 to 120 parts by mass is usually preferred per 100 parts by mass of the rubber component. .

  When silica is used as the reinforcing filler, it is preferable to use a silane coupling agent in combination. The kind of silane coupling agent is not particularly limited, and those generally used in rubber compositions for tires can be used. Examples thereof include sulfide silane and mercaptosilane. The content of the silane coupling agent is preferably 5 to 15% by mass with respect to silica.

  In addition to the components described above, the rubber composition according to the present invention includes various additives commonly used in tire rubber compositions such as zinc white, stearic acid, anti-aging agent, wax, vulcanizing agent, and vulcanization accelerator. An agent can be appropriately blended. Examples of the vulcanizing agent include sulfur and sulfur-containing compounds, and are not particularly limited. However, the blending amount is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it is 0.5-5 mass parts. The rubber composition is prepared by kneading according to a conventional method using a rubber kneader such as an ordinary Banbury mixer or kneader.

  The rubber composition of the present invention as described above can be used, for example, as a tread rubber or a sidewall rubber of a tire, and is particularly suitably used for a tread rubber. A tire can be formed by vulcanizing and molding the rubber composition at, for example, 140 to 180 ° C. according to a conventional method.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. The blending ratio shown below is based on mass (“parts by mass”, “mass%”, etc.) unless otherwise specified.

[Examples and Comparative Examples]
In accordance with the composition shown in Table 1 below (parts by mass unless otherwise specified), first, components other than sulfur and vulcanization accelerator are mixed, then sulfur and vulcanization accelerator are added and mixed to obtain a rubber composition for tires. Prepared. The details of each formulation in Table 1 are as follows.

Modified S-SBR (containing amino group): “HPR350” manufactured by JSR Corporation (Tg = −35 ° C., St = 21)
Unmodified S-SBR: “VSL5025-0HM” manufactured by LANXESS (Tg = −14 ° C., St = 25)
-BR: “BR150B” manufactured by Ube Industries, Ltd.
・ Silica: Tosoh Silica Co., Ltd. “Nip seal AQ” (BET: 200 m ² / g)
Silane coupling agent: Evonik Degussa “Si69”
Carbon black: “Dia Black N339” manufactured by Mitsubishi Chemical Corporation
・ Process oil: “JOMO process NC140” manufactured by Japan Energy Co., Ltd.
・ Zinc flower: "Zinc flower No. 1" manufactured by Mitsui Mining & Smelting Co., Ltd.
Anti-aging agent: “NOCRACK 6C” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
・ Stearic acid: “Lunac S20” manufactured by Kao Corporation
・ Wax: Nippon Seiwa Co., Ltd. “OZOACE0355”
・ Sulfur: “5% oil-treated fine powder sulfur” manufactured by Tsurumi Chemical Co., Ltd.
・ Vulcanization accelerator: “Soxinol CZ” manufactured by Sumitomo Chemical Co., Ltd.
Α-olefin-maleic anhydride copolymer: “Diacarna 30” manufactured by Mitsubishi Chemical Corporation
Styrene-maleic anhydride copolymer: “SMA3000” manufactured by Sartomer Japan
Isobutylene-maleic anhydride copolymer: “Isoban-600” manufactured by Kuraray Co., Ltd.

  The wear resistance of rubber samples obtained by vulcanizing each rubber composition obtained by heating at 150 ° C. for 30 minutes was measured by the following method. The results are shown in Table 1.

  Wear resistance performance: In accordance with JIS K6264, using a Lambourn abrasion tester (manufactured by Iwamoto Seisakusho Co., Ltd.), the wear amount was measured under the conditions of a load of 40 N, a slip rate of 30%, and a sandfall amount of 20 g / min. The reciprocal was shown by an index (“Abrasion amount of Comparative Example 1” × 100 / “Abrasion amount of each test piece”) with the value of Comparative Example 1 being 100. A larger index means better wear resistance.

  From the results shown in Table 1, it can be seen that all of the examples in which a predetermined amount of a copolymer of α-olefin and maleic anhydride was added to the rubber composition improved the wear resistance. In particular, in Examples 1 and 2 using the modified S-SBR having an amino group, the wear resistance performance was remarkably improved, and a synergistic effect was obtained by the combined use of the copolymer and the modified diene rubber. It is shown.

  The copolymer of α-olefin and maleic anhydride added in the examples is also used as a wax. However, as shown in Comparative Example 2, even if the amount of the wax is increased by 2 parts, no improvement in wear resistance is observed. It can be seen that the wear resistance is not improved by the addition of ordinary paraffin wax.

  Further, from the results of Comparative Examples 3 and 4, even in the case of a maleic anhydride copolymer similar to the copolymer used in the present invention, the wear resistance performance is obtained when the side chain does not have a sufficiently long alkyl group. It can be seen that does not improve.

  Furthermore, it can be seen from the results of Comparative Examples 5 and 6 that if the copolymer content defined in the present invention is out of the range, the desired effect of improving wear resistance cannot be obtained. In addition, when the content of the copolymer is excessive, softening due to the addition of the copolymer becomes remarkable, so that it is considered that the wear resistance performance is lowered.

  The rubber composition of the present invention can be used for various tires such as passenger cars, light trucks, trucks and buses.

Claims (3)

0.5 to 20 parts by mass of an α-olefin and maleic anhydride copolymer represented by the following general formula (1) and 5 to 150 reinforcing fillers with respect to 100 parts by mass of the diene rubber component A rubber composition for tires, comprising a part by mass.

In the formula, R represents a linear or branched alkyl group having 20 to 70 carbon atoms, and n represents an integer of 1 or more. The tire rubber composition according to claim 1, wherein the amino group-containing modified diene rubber contains 15% by mass or more of the diene rubber component. A pneumatic tire using the tire rubber composition according to claim 1.