JP2008150435A - Rubber composition for tire and pneumatic tire - Google Patents

Abstract

Provided are a tire rubber composition that achieves both tire handling stability, low fuel consumption, and wear resistance without impairing processability, and a pneumatic tire using the rubber composition.
30 to 120 parts by weight of a filler such as silica, and 1 to 10 parts by weight of at least one compound (A) selected from fatty acid metal salts and fatty acid amides with respect to 100 parts by weight of a diene rubber. 1 to 10 parts by weight of at least one compound (B) selected from trihydric alcohols such as trimethylolpropane and polyethers of derivatives thereof, wherein the weight ratio of the compound (A) to the compound (B) is It is a rubber composition for tires where A / B = 0.25-5.
[Selection figure] None

Description

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

  In recent years, the characteristics required of automobile tires are diverse, such as low fuel consumption, handling stability, wear resistance, and ride comfort, and silica has been used as a filler to improve these performances. Yes.

  However, when silica is compounded to improve fuel efficiency, it becomes difficult to disperse silica during mixing of the rubber composition, the viscosity increases, and the processability such as increase in the mixing step and decrease in the extrusion speed is reduced. Problems arise.

  Then, in order to improve workability, adding a fatty acid metal salt has been proposed (see Patent Documents 1 and 2 below). Fatty acid metal salts have a viscosity-reducing effect, leading to improved processability, but may also be a factor in inhibiting vulcanization, and steering stability is reduced by lowering rigidity due to lower rubber hardness. A new problem arises that it deteriorates and wear resistance decreases.

  In addition, as a technique for improving processability, it has also been proposed to add a polyether or a derivative thereof (see Patent Documents 3 to 5 below). Polyether and its derivatives are effective in reducing viscosity and improving wear resistance by improving the dispersibility of silica. However, scorching is accelerated and processability in another sense is impaired. Also, there is a drawback that the effect of reducing the viscosity is smaller than that of the fatty acid metal salt.

By the way, Patent Document 5 is characterized in that a polyether is added to improve processability as described above. In paragraph 0021 of the same document, rubber, filler, polyether, and rubber are used. In addition to the auxiliary agent and the crosslinking agent, it is described that a zinc salt of a fatty acid may be blended as an optional component. However, Patent Document 5 does not specifically describe an example in which polyether and fatty acid zinc are combined, and does not disclose what kind of effect is achieved by the combination of both.
JP 2002-097304 A JP-A-9-151276 JP 2005-343963 A JP 2003-128840 A JP 2001-261890 A

  The present invention has been made in view of the above points, and a tire rubber composition capable of achieving both the steering stability, low fuel consumption, and wear resistance of a tire without impairing workability, and the same An object of the present invention is to provide a pneumatic tire using the tire.

  The rubber composition for a tire according to the present invention is 30 to 120 parts by weight of a filler, and at least one compound (A) 1 to 10 selected from a fatty acid metal salt and a fatty acid amide with respect to 100 parts by weight of a diene rubber. 1 part by weight and at least one compound (B) selected from a trihydric alcohol and a polyether derivative thereof, and the weight ratio of the compound (A) to the compound (B) is A / B = 0.25-5.

  Moreover, the pneumatic tire according to the present invention has a tread made of the rubber composition.

  According to the present invention, by combining the compound (A) comprising a fatty acid metal salt or a fatty acid amide and the compound (B) comprising a polyether of a trihydric alcohol or a derivative thereof at a predetermined ratio, the scorch property is obtained. It is possible to reduce the viscosity at the time of mixing without impairing the workability and to ensure the workability.In addition, while maintaining the workability in this way, the steering stability of the tire by maintaining the rubber hardness, the low fuel consumption and the resistance It is possible to achieve both wear characteristics.

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  In the rubber composition of the present invention, as the diene rubber, various diene rubbers generally used in tire rubber compositions can be used, such as natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, Examples thereof include styrene-isoprene rubber, butadiene-isoprene rubber, and nitrile rubber. These may be used alone or in combination of two or more. Among the above, the diene rubber is preferably a styrene-butadiene rubber alone or a blend of a styrene-butadiene rubber and another diene rubber. In this case, as another diene rubber to be blended Is preferably natural rubber or butadiene rubber.

  In the rubber composition of the present invention, as the filler, white inorganic fillers such as silica, clay and talc, carbon black and the like can be used. Silica is preferably used from the viewpoints of low fuel consumption and braking performance on wet road surfaces, and silica alone or a combination of silica and carbon black is preferred. Silica and carbon black are preferably blended at a ratio of silica / carbon black = 0.7 / 1 to 1/0.

  The blending ratio of the filler is 30 to 120 parts by weight, preferably 50 to 100 parts by weight with respect to 100 parts by weight of the diene rubber.

  When silica is blended, it is preferable to blend a silane coupling agent that binds silica and diene rubber to the rubber composition. The silane coupling agent is not particularly limited, and examples thereof include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) tetrasulfide, 3 -Mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-nitropropyltrimethoxysilane, γ-aminopropyltriethoxysilane and the like. The silane coupling agent is usually blended in an amount of 1 to 20 parts by weight with respect to 100 parts by weight of silica.

  In the rubber composition of the present invention, at least one compound (A) selected from fatty acid metal salts and fatty acid amides is blended. By blending such a compound (A), the effect of reducing the viscosity mainly due to the lubricating action is exerted, and the workability can be improved.

  Although it does not specifically limit as a fatty acid in the said fatty acid metal salt, A C5-C36 saturated or unsaturated fatty acid is mentioned, More preferably, for example, octanoic acid, lauric acid, stearic acid, octenoic acid, oleic acid, Examples include eicosanoic acid, and lauric acid, stearic acid, oleic acid, and eicosanoic acid are more preferable. Examples of the metal salt include alkali metal salts such as sodium salt and potassium salt, alkaline earth metal salts such as magnesium salt and calcium salt, transition metal salts such as zinc salt, cobalt salt and copper salt. Among these, zinc salts are particularly preferable.

  Although it does not specifically limit as a fatty acid in the said fatty acid amide, Like a fatty acid metal salt, a C5-C36 saturated or unsaturated fatty acid is mentioned, Octanoic acid, lauric acid, stearic acid, octenoic acid, oleic acid, eicosane An acid etc. are mentioned as a preferable example.

  In the rubber composition of the present invention, at least one compound (B) selected from a trihydric alcohol and a polyether derivative thereof is blended. By blending such a compound (B), the viscosity can be reduced by the effect of improving the dispersibility of silica, the workability can be improved, and the effect of improving the wear resistance can be obtained.

  As the trihydric alcohol, a trivalent alkanetriol having 3 to 24 carbon atoms can be used. For example, glycerin, 1,2,3-butanetriol, 2-methyl-1,2,3-propanetriol, 2 -Methyl-2,3,4-butanetriol, trimethylolethane, trimethylolpropane and the like. Trimethylolpropane (TMP) is preferable.

  Further, as the polyether as a derivative of a trihydric alcohol (that is, a polyether derivative), a polyether compound obtained by adding an alkylene oxide such as ethylene oxide or propylene oxide to a trihydric alcohol is preferable, and trimethylolpropane is more preferable. Is a compound in which an alkylene oxide is added. The number of moles of alkylene oxide added is preferably 0.7 to 7 moles, more preferably 0.7 to 3 moles, per mole of hydroxyl group of the trihydric alcohol.

  The compounding ratio of the compound (A) is 1 to 10 parts by weight, more preferably 2 to 5 parts by weight with respect to 100 parts by weight of the diene rubber. Moreover, the compounding ratio of the said compound (B) is 1-10 weight part with respect to 100 weight part of diene rubbers, More preferably, it is 2-5 weight part. Moreover, the compounding ratio of the compound (A) and the compound (B) is A / B = 0.25 to 5, more preferably 0.6 to 2.5, and further preferably 1 to 5 by weight ratio. 2.5. When the blending ratio of both is out of the above range, it is impossible to achieve both the steering stability of the tire, the low fuel consumption and the wear resistance while maintaining the workability including the scorch property. That is, the compound (A) is excellent in the viscosity reduction effect, but causes a decrease in rubber hardness and a decrease in wear resistance, and may be a factor for inhibiting vulcanization in some cases. On the other hand, the compound (B) has a viscosity reducing effect and improves the wear resistance, but has a drawback of poor scorch properties. In order to exert a synergistic effect by combining such compound (A) and compound (B), there is a specific blending ratio. According to the present invention, by using both compounds within the above range, As a result, the present invention has an excellent effect of improving the properties, having little influence on other physical properties, and improving fuel efficiency.

  In addition to the components described above, the rubber composition of the present invention is generally used in rubber compositions for tire treads such as anti-aging agents, zinc white, stearic acid, softeners, vulcanizing agents, and vulcanization accelerators. Various additives can be blended.

  The rubber composition of the present invention can be used in various parts such as a tread part and a sidewall part of a pneumatic tire, and particularly preferably used in a tread part. In that case, a tread of a pneumatic tire can be formed by vulcanization molding according to a conventional method.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Preparation of rubber composition)
Using a Banbury mixer, a rubber composition was prepared according to the formulation shown in Table 1 below. Details of each component in the table are as follows.

SSBR: solution polymerized styrene-butadiene rubber, “VSL 5025-0HM” manufactured by Bayer,
-BR: butadiene rubber, "BR150B" manufactured by Ube Industries,
・ Silica: Tosoh Silica “Nip Seal AQ”
・ Carbon: Carbon black, “Dia Black N339” manufactured by Mitsubishi Chemical,
Coupling agent: Degussa polysulfide silane “Si-69”.

・ Fatty acid zinc: "Acchiplast PP" manufactured by Rhein Chemie,
・ Fatty acid amide: “Afflux 16” manufactured by Rhein Chemie,
TMP: trimethylolpropane manufactured by Nacalai Tesque,
Polyether: A silica-supported trimethylolpropane ethylene oxide adduct (active ingredient (polyether ratio) = 50% by weight), “silica activator KA9202” manufactured by LANXESS.

  In each rubber composition, 3 parts by weight of zinc white (“Zinc Hana 1” made by Mitsui Metals) and stearic acid (“Lunac S-25” made by Kao) are used as a common formulation for 100 parts by weight of diene rubber. 2) parts by weight, 2 parts by weight of anti-aging agent (“Antigen 6C” manufactured by Sumitomo Chemical), 40 parts by weight of oil (process oil “X-140” manufactured by JOMO), wax (“Ozoace 0355” manufactured by Nippon Seiwa) 2 Parts by weight, sulfur ("5% oil-filled fine powder sulfur" manufactured by Tsurumi Chemical Co., Ltd.) 1.5 parts by weight, vulcanization accelerator ("Soxinol CZ" manufactured by Sumitomo Chemical), 1.8 parts by weight, vulcanization accelerator (Ouchi) Shinko Chemical Co., Ltd. "Noxeller D") 2.0 parts by weight was blended.

(Evaluation)
About each rubber composition, while measuring Mooney viscosity and scorch, hardness was measured about the test piece vulcanized | cured at 160 degreeC * 20 minutes. A pneumatic tire was produced using each rubber composition. The tire was manufactured by applying each rubber composition to a cap tread of a 205 / 65R15 94H radial tire for a passenger car having a tread with a cap / base structure, and vulcanizing and molding the rubber composition according to a conventional method. The obtained tires were evaluated for low fuel consumption, braking performance on wet road surfaces, and wear resistance. Each evaluation method is as follows.

Mooney viscosity: Mooney viscosity was measured at a test temperature of 100 ° C. in accordance with JIS K6300, and displayed as an index with the value of Comparative Example 2 taken as 100. The smaller the index, the lower the viscosity and the better.

Scorch property: Based on JIS K6300, scorch was measured at a test temperature of 125 ° C. and displayed as an index with the value of Comparative Example 2 taken as 100. A larger index indicates a slower and better scorch.

Hardness: Based on JIS K6253, using a type A durometer, the hardness was measured at 23 ° C., and the value was expressed as an index with the value of Comparative Example 2 being 100. The larger the index, the higher the hardness and the better the handling stability when used as a tire.

-Low fuel consumption: The tire was mounted with a rim of 15 × 6.5 JJ, the rolling resistance was measured when running at 23 km and 80 km / h on a rolling resistance measuring drum with an air pressure of 230 kPa and a load of 450 kgf. The value of Comparative Example 2 is expressed as an index, and the smaller the index is, the smaller the rolling resistance is, and thus the better the fuel efficiency is.

-Braking property on wet road surface: The rim used was set to 15 × 6.5JJ on a test trailer, the vehicle was driven on a wet asphalt road surface, the tire was locked at a speed of 64 km / h, and the braking force was measured. The value of Comparative Example 2 is displayed as an index with the value of 100, and the larger the index, the better the braking performance.

Abrasion resistance: The rim used was 15 × 6.5JJ, and the four pneumatic tires were mounted on a 2000cc FF vehicle, and the remaining groove after running 10,000 km was measured while rotating back and forth every 2500 km. The value of Comparative Example 2 is expressed as an index, and the larger the index, the better the wear resistance.

  As shown in Table 1, from the comparison between Comparative Example 1 and Comparative Example 2, by blending fatty acid zinc, the Mooney viscosity was reduced and the processability was excellent, but the hardness and wear resistance were lowered. On the other hand, in Comparative Examples 3 and 4 in which trihydric alcohol or polyether was blended instead of fatty acid zinc, the hardness and wear resistance were improved, but the effect of reducing Mooney viscosity was insufficient, and the scorch Sex was significantly worse.

  Moreover, although the trihydric alcohol and polyether of the compound (B) are used in combination with the fatty acid zinc and the fatty acid amide of the compound (A), in Comparative Examples 5 and 6, the ratio (A / B) of both is too small. The effect of reducing Mooney viscosity was insufficient, and the scorch property was greatly deteriorated. Moreover, in Comparative Examples 7 and 8 in which the ratio (A / B) of both was too large, although the effect of reducing the viscosity was excellent, the effect of improving the hardness and wear resistance was insufficient.

  On the other hand, when the compound (A) and the compound (B) are used in combination, and the ratio (A / B) of the two is within the predetermined range, the scorch properties are not impaired. The Mooney viscosity was greatly reduced, the rubber hardness was large, the wear resistance was improved, and the fuel efficiency was also excellent.

Claims (3)

  30 to 120 parts by weight of a filler, 1 to 10 parts by weight of at least one compound (A) selected from fatty acid metal salts and fatty acid amides, a trihydric alcohol and its polyether with respect to 100 parts by weight of diene rubber 1 to 10 parts by weight of at least one compound (B) selected from derivatives, and the weight ratio of the compound (A) to the compound (B) is A / B = 0.25 to 5 Rubber composition.   The tire rubber composition according to claim 1, wherein the compound (B) is an alkylene oxide adduct of trimethylolpropane.   A pneumatic tire having a tread made of the rubber composition according to claim 1.