JP5474293B2 - Rubber composition and pneumatic tire - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a rubber composition containing zeolite, and more specifically, rubber containing surface-treated zeolite fine particles to improve tire rolling resistance while maintaining rubber properties such as strength and wear resistance. The present invention relates to a composition and a pneumatic tire using the rubber composition.

  For example, rubber compositions used in treads for pneumatic tires are strongly demanded to reduce rolling resistance due to market demands for low fuel consumption, improve wet performance and handling stability (grip performance), and are more durable and economical. It is demanded that each rubber characteristic such as wear resistance, which is excellent in terms of performance, be balanced.

  Conventionally, fillers such as carbon black, silica, clay and the like have been blended and used in rubber compositions, and these filler characteristics are uniformly dispersed in the rubber composition. It is indispensable for balancing.

  For example, the rubber composition constituting at least one of the tire sidewall reinforcing layer and the bead filler is a rubber component containing a conjugated diene polymer having an alkoxysilyl group in the molecule, and zeolite as a reinforcing inorganic filler. A pneumatic tire excellent in blended rolling resistance and run-flat durability is described (Patent Document 1).

In addition, a rubber composition for studless tires using porous particles made of crystalline zeolite having a small average pore diameter as a frictional effect is improved by utilizing the scratching effect of the porous particles on the tire tread surface against the ice surface. Has been proposed (Patent Document 2), but it cannot be said that the reinforcing property, wear resistance, and the like are sufficient when a zeolite is blended with a reinforcing rubber member such as a tread portion or a sidewall portion of a tire.
JP 2002-103912 A JP 2000-44732 A

  The present invention provides a rubber composition capable of improving the rolling resistance of a tire while maintaining rubber properties such as strength and wear resistance by improving the dispersibility of zeolite, and a pneumatic tire using the rubber composition. For the purpose.

  The present inventors diligently studied to solve the above-mentioned problems, and found that by modifying the surface of the zeolite, the dispersibility of the zeolite in the rubber can be improved, thereby improving the rubber characteristics. Is.

  That is, the invention according to claim 1 is a rubber composition characterized in that diene rubber is used as a rubber component and surface-treated zeolite fine particles are contained.

  According to a second aspect of the present invention, the surface treatment agent is at least one selected from fatty acids, resin acids, quaternary ammonium salts, and lignin sulfonates, and the amount of the surface treatment agent attached is that of untreated zeolite. It is 0.1 to 20 weight%, It is a rubber composition of Claim 1 characterized by the above-mentioned.

  The invention according to claim 3 is the rubber composition according to claim 1 or 2, wherein the surface-treated zeolite fine particles have an average particle size of 10 μm or less.

  The invention according to claim 4 contains 5 to 70 parts by weight of the fine particles of the surface-treated zeolite with respect to 100 parts by weight of the rubber component. The rubber composition.

  The invention according to claim 5 is the rubber composition according to any one of claims 1 to 4, wherein the zeolite is an artificial zeolite.

  The invention according to claim 6 is a pneumatic tire characterized by using the rubber composition according to any one of claims 1 to 5 for at least a part of the tire.

  According to the present invention, by containing fine particles of a surface-treated zeolite, the rolling resistance of the tire is improved while maintaining rubber properties such as strength and wear resistance, and a zeolite comprising an inorganic component containing silicic acid and aluminum is provided. The rubber composition and pneumatic tire which adapt to the environment which reduced the usage-amount of the petrochemical product by using can be provided.

  Embodiments of the present invention will be described below.

  The rubber composition of the present invention uses a diene rubber as a rubber component. The diene rubber is composed of natural rubber (NR), epoxidized natural rubber (ENR), and diene synthetic rubber. Examples of the diene synthetic rubber include styrene butadiene rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). It is done. These diene rubbers may be used alone or in combination of two or more.

  The zeolite used in the present invention may be either natural zeolite or artificial zeolite, or a mixture thereof, but artificial zeolite is preferred.

  Natural zeolite is produced by the interaction of lava and water and is produced mainly from hot springs. Zeolites that occur in pillow-shaped lava, in the deep sea, and also in contact with the groundwater of volcanic ash, such as Yugahara Zeolites, Rhizorites, Zeolites, Zanthite, Cyptirolite, pyroxene, soda zeolite, etc. .

  Artificial zeolite is a zeolite obtained by artificially converting a composition containing an amorphous aluminum silicate salt composed of inorganic components containing silicic acid and aluminum by alkali treatment, and its main component is Philipsite, faujasite, zeolite A, hydroxysodalite and the like, and may contain a small amount of other components. In addition, as a non-zeolite component other than the zeolite, that is, non-zeolite components, organic substances, iron, other impurities, intermediate products up to the zeolite, and the like coexist.

  The zeolite used in the present invention is preferably used as fine particles having an average particle size of 10 μm or less by pulverizing and classifying the above zeolite by a known method.

  When the average particle size of the zeolite fine particles exceeds 10 μm, the reinforcing property and wear resistance are lowered when used in a tire tread. Here, the average particle size is preferably 5 μm or less from the viewpoint of suppressing a decrease in reinforcement and wear resistance. The lower limit of the average particle diameter is not particularly limited, but if it is less than 0.1 μm, the handling properties in the production process and the dispersibility in the rubber are lowered. The pulverization method is not particularly limited, and examples thereof include wet pulverization using a roll mill, dry pulverization using a ball mill, and a turbo mill.

  Examples of the surface treatment agent for zeolite include fatty acids, resin acids, quaternary ammonium salts, and lignin sulfonates. These may be used alone or in combination of two or more.

  The fatty acid may be a saturated fatty acid or an unsaturated fatty acid. Further, it may be a linear fatty acid, a branched fatty acid, or a fatty acid derivative.

  Examples of fatty acids include butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, myristic acid, pentadecylic acid, palmitic acid, heptadecanoic acid, stearic acid and other saturated fatty acids, oleic acid, maleic acid, Examples thereof include unsaturated fatty acids such as linoleic acid and linolenic acid. Examples of the fatty acid derivatives include fatty acid metal salts such as barium stearate, calcium stearate, magnesium stearate, and zinc stearate, fatty acid esters such as higher alcohol fatty acid ester and polyethylene glycol alkyl ester, oleic acid amide, erucic acid amide, stearin. And fatty acid amides such as acid amides.

  Examples of the resin acid include abietic acids such as abietic acid, dehydroabietic acid, dihydroabietic acid or polymers thereof, disproportionated rosin, hydrogenated rosin, polymerized rosin, and salts thereof (for example, alkali metal salts, alkaline earths). Metal salts) or esters (for example, rosin pentaerythritol ester, glycerol ester, hydrogenated rosin methyl ester, triethylene glycol ester, pentaerythritol ester).

  Quaternary ammonium salts are tetraethylammonium bromide, tetrabutylammonium chloride, cetyltrimethylammonium bromide, n-dodecyltrimethylammonium bromide, cetylpyridium chloride, 1,8-diaza-bicyclo (5,4,0) undecene-7- Examples include benzylammonium chloride, cetylpyridium iodide, lauryltrimethylammonium chloride, stearyltrimethylchloride, distearyldimethylammonium chloride, behenyltrimethylammonium chloride, and tetramethylammonium chloride.

  As the lignin sulfonate, an alkali metal salt or alkaline earth metal salt of lignin is used. Specific examples of the lignin sulfonate include potassium salt, sodium salt, calcium salt, magnesium salt, lithium salt, barium salt and the like, and treatment with a mixed salt containing one or more of these may be performed. .

  Moreover, it is preferable that the said lignin sulfonate consists of lignin obtained by a sulfite pulp method.

  In this invention, it is preferable that the processing adhesion amount of the said surface treating agent is 0.1 to 20 weight% of the amount of untreated zeolite, More preferably, it is 1 to 10 weight%. If the adhesion amount is less than 0.1% by weight, the surface modification effect of the zeolite fine particles is insufficient and the effect of improving the dispersibility cannot be obtained, and if it exceeds 20% by weight, no further effect can be expected.

  The processing method for the zeolite fine particles is not particularly limited, and the powder of the surface treatment agent and the zeolite or zeolite fine particles are mixed with a mixer or the like, the mixture is heated, or an aqueous solution of the surface treatment agent is added. Examples of the treatment method include spraying on zeolite and drying. Classification or pulverization may be performed after the surface treatment.

  In addition, the particle size distribution of the fine particles of the surface-treated zeolite preferably has peaks in the range of 0.1 to 1 μm and 1 to 10 μm. By having a peak at 0.1 to 1 μm, the reinforcing property of the rubber composition is improved, and the strength and wear resistance are increased. can do. The area of the peak is about 0.1 to 1 μm: 1 to 10 μm = 2/8: 8/2.

  The rubber composition of the present invention contains 5 to 70 parts by weight, preferably 10 to 50 parts by weight, of the fine particles of the surface-treated zeolite with respect to 100 parts by weight of the rubber component. When the blending amount is less than 5 parts by weight, the effect of improving the workability and rolling resistance is small, and when it exceeds 70 parts by weight, the rubber hardness is increased and the strength and wear resistance are decreased.

  In the rubber composition of the present invention, reinforcing agents such as carbon black and silica can be used together with the zeolite fine particles, and both carbon black and silica may be used in combination.

Carbon black is not particularly limited, and for example, carbon black having a colloidal characteristic with a BET specific surface area (BET) of 25 to 160 m ² / g and a DBP oil absorption of 80 ml / 100 g or more can be used.

  Examples of such carbon black include various grades such as ASTM numbers N110, N220, N330, N550, and N660.

  The compounding amount of the carbon black is about 0 to 150 parts by weight with respect to 100 parts by weight of the rubber component. When the blending amount of carbon black exceeds 150 parts by weight, exothermic deterioration and workability deterioration are exhibited.

Further, as silica, for example, those having colloidal characteristics with a BET of 250 m ² / g or less and a DBP oil absorption of 250 ml / 100 g or less are preferable. By using silica having such a large particle size and a small structure, it is possible to maintain processability, suppress heat generation, and reduce rolling resistance.

  The compounding amount of the silica is about 20 to 120 parts by weight with respect to 100 parts by weight of the rubber component. If the compounding amount of the silica is less than 20 parts by weight, the effect of reducing rolling resistance cannot be sufficiently exhibited.

  The silica is not particularly limited as long as it satisfies the colloidal characteristics, and examples thereof include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, and the like. Wet silica having both low rolling resistance is preferable, and is also preferable from the viewpoint of excellent productivity. As commercial products, Nipsil AQ and VN3 manufactured by Tosoh Silica Co., Ltd., PR and USQ-A manufactured by Tokuyama Co., Ltd., Ultrazil VN3 manufactured by Degussa, and the like can be used. BET is measured according to the BET method described in ISO 5794, and DBP oil absorption is measured according to the method described in JIS K6221.

  Furthermore, as the silica, surface-treated silica that has been surface-treated with amines or organic polymers to improve the affinity with the polymer may be used.

  In addition, when using a silica, it is preferable to use 2-20 weight% of silane coupling agents with respect to the said amount of silica, More preferably, it uses in the range of 2-15 weight%. Examples of the silane coupling agent include sulfur-containing silane coupling agents such as bis (3-triethoxysilylpropyl) tetrasulfide and bis (3-triethoxysilylpropyl) disulfide, and the following general formula (1). Examples include protected mercaptosilane.

_{(CxH 2 x +1 O) 3} Si- (CH 2) y-S-CO-CzH 2 z +1 ...... (1)
In the formula, x is an integer of 1 to 3, y is an integer of 1 to 5, and z is an integer of 5 to 9.

  The blending amount of the carbon black or silica can be reduced by substituting the blending amount of the clay. In particular, in the case of silica, the amount of silane coupling agent corresponding to the silica weight loss can be reduced.

  In addition to the above components, the rubber composition of the present invention includes process oil, zinc white, stearic acid, wax, anti-aging agent, vulcanizing agent, vulcanization accelerator, and vulcanization aid that are commonly used in the tire industry. Various compounding agents such as resins can be appropriately blended and used as necessary within the range not impairing the effects of the present invention.

  The rubber composition of the present invention can be produced according to a conventional method using various kneading machines such as a Banbury mixer, a roll, a kneader and the like by blending various compounding agents with fine particles of raw rubber and zeolite, and starting with tire treads. Can be used for each part of the tire such as a sidewall and a bead.

  The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

<Preparation of fine particles of zeolite>
Untreated zeolite (zeolite-1): Chubu Electric Power Co., Ltd., “Cyculus” average particle size of 30 μm.
Fine particle zeolite (Zeolite-2): Zeolite-1 pulverized with a ball mill and then classified to an average particle size of 2 μm.
Fine particles / surface-treated zeolite (zeolite-3): Zeolite-1 pulverized with a ball mill, classified to an average particle size of 2 μm, and surface-treated with stearic acid to an amount of 4% by weight.
Fine particles / surface-treated zeolite (zeolite-4): Zeolite-1 pulverized with a ball mill, classified to an average particle size of 2 μm, and surface-treated with stearic acid to a weight of 10% by weight.
Fine particles / surface-treated zeolite (zeolite-5): Zeolite-1 was pulverized with a ball mill, classified to an average particle size of 8 μm, and surface-treated with stearic acid to an amount of 4% by weight.
・ Fine particles / Surface-treated zeolite (Zeolite-6): Zeolite-1 is pulverized with a ball mill, classified to an average particle size of 2 μm, and attached with lignin sulfonic acid sodium salt (Nippon Paper Chemical Co., Ltd. “Vanilex N”) Surface treated to 4% by weight.

<Preparation of rubber composition>
Using a Banbury mixer with a capacity of 20 liters, rubber compositions were prepared according to the formulation shown in Tables 1 to 3 below. Each component of Tables 1-3 and common compounding components are as follows. Table 1 shows the formulation for tread (SBR / BR blending system), Table 2 for the sidewall (NR / BR blending system), and Table 3 for the tread and bead filler (NR / ENR blending system).

[Rubber component]
・ Natural rubber (NR): RSS # 3 (made in Malaysia)
・ Styrene butadiene rubber (SBR): Asahi Kasei Corporation “Tuffden E-50”
-Butadiene rubber (BR): JSR Corporation "BR01"
-Epoxidized natural rubber (ENR): MMG, 25 mol% epoxidized natural rubber “EPOXY PRENE25”

[Common ingredients]
・ Silica: Tosoh Silica Co., Ltd. “Nipseal AQ”
Silane coupling agent: Degussa "Si-69"
・ Carbon Black: Cabot Japan Co., Ltd. “Show Black N330”
・ Zinc flower: Mitsui Metal Mining Co., Ltd. “Zinc flower 1”
・ Stearic acid: Kao Corporation “Lunac S-20”
・ Aroma oil: Japan Energy “Process X-140”
・ Anti-aging agent 6C: “Sant Flex 6PPD” from Flexis
・ Wax: Nippon Seiwa Co., Ltd. “Ozoace 0355”
・ Sulfur: Hosoi Chemical Co., Ltd. “Powder sulfur 150 mesh for rubber”
・ Vulcanization accelerator CZ: Ouchi Shinsei Chemical Co., Ltd. “Noxeller CZ-G”

<Evaluation>
Each of the obtained rubber compositions was applied to a tire tread having a cap / base structure tread (Table 1) and applied to a sidewall (Table 2). Both tires were radial tires of size 205 / 65R15 94H. Manufactured according to conventional methods. And about each obtained tire, rolling resistance characteristic, wet performance, and abrasion resistance were evaluated. The rubber compositions in Tables 2 and 3 were evaluated for fatigue resistance, heat build-up, and hardness. Each evaluation method is as follows. The results are shown in Tables 1-3.

[Rolling resistance characteristics]
Measure the rolling resistance when running at 23km and 80km / h with a uniaxial drum tester for measuring rolling resistance with a tire of 15x6.5JJ and a pneumatic pressure of 230kPa and a load of 450kgf. did. The value was expressed as an index with the value of Comparative Example 1 and Comparative Example 4 as 100. The smaller the index, the smaller the rolling resistance and thus the better the fuel efficiency.

[Wet performance]
A 2000cc domestic FF car is equipped with four of the above radial tires, runs on asphalt roads that have been sprinkled with water at a depth of 2 to 3 mm, operates the ABS at a speed of 90 km / h, and reduces the braking distance to 20 km / h. It was measured. It displays with the index | exponent which set the value of the comparative example 1 to 100, and shows that it is excellent in wet performance, so that an index | exponent is large.

[Abrasion resistance]
Two kinds of radial tires above 2000cc domestic FF, adjusted to 200kPa internal pressure and attached to the front and rear wheels respectively. After running 20,000km on the general road while rotating every 5,000km, The residual groove depth of the tread was measured to determine the wear amount, and the wear resistance was evaluated. The value of Comparative Example 1 is expressed as an index, which is 100. The larger the index, the better the wear resistance.

[Fatigue resistance]
In accordance with JIS K6270, fatigue life was measured with a demercher tester. The value of Comparative Example 4 is expressed as an index, and the greater the index, the better the fatigue resistance.

[Exothermic]
A loss factor tan δ was measured under the conditions of initial strain 10%, dynamic strain 2%, frequency 50 Hz, and temperature 80 ° C. using a rheometer E4000 manufactured by UBM Co., Ltd. in accordance with JIS K-6394. It displays with the index | exponent which set the value of the comparative example 7 to 100, and shows that heat_generation | fever is so small that a numerical value is small.

[hardness]
Based on JIS K6253, spring hardness (A type) was measured at 23 ° C. The comparative example 7 is indicated by an index of 100.

  As described above, the rubber composition of the present invention is a pneumatic tire that reduces tire rolling resistance and achieves low fuel consumption by being used in each part of the tire such as a tire tread, sidewalls, and bead parts. Can be provided.

Claims (4)

Diene rubber as a rubber component, containing zeolite fine particles surface-treated with a surface treating agent that is at least one selected from fatty acids, resin acids, quaternary ammonium salts and lignin sulfonates,
The adhesion amount of the surface treatment agent is 0.1 to 20% by weight of the untreated zeolite;
The average particle diameter of the fine particles of the surface-treated zeolite Ri der less 10 [mu] m,
A rubber composition for tire treads, sidewalls or beads . The rubber composition according to claim 1, wherein the particle size distribution of the fine particles of the surface-treated zeolite has peaks in the range of 0.1 to 1 µm and 1 to 10 µm, respectively. Wherein the rubber component 100 parts by weight, the rubber composition according to claim 1 or 2, characterized in that it contains 5 to 70 parts by weight of fine particles of the surface-treated zeolite. The rubber composition according to any one of claims 1 to 3 , wherein the zeolite is artificial zeolite.