JP4971648B2 - Rubber composition and pneumatic tire - Google Patents

Description

  The present invention relates to a rubber composition, and more particularly to a rubber composition suitable for a studless tire used for running on snowy and icy roads, and a pneumatic tire using the rubber composition for a tread.

  In general, a tread rubber of a studless tire used for running on an icy and snowy road is required to have excellent performance on ice and snow. Conventionally, in order to improve these performances, the tread rubber has a low hardness at low temperatures and can be easily deformed, thereby improving the ground contact property and further improving the friction property on ice. In addition, methods such as blending hard materials such as vegetable powders have been proposed.

  For example, Patent Document 1 below proposes a technique in which a tread is provided with a foamed rubber layer having closed cells with an average cell diameter of 1 to 120 μm and a foaming ratio in the range of 1 to 100%.

  Patent Document 2 below proposes a technique for obtaining a water removal effect and a scratching effect by blending gas-filled thermoplastic resin particles with tread rubber and providing minute uneven portions on the ground contact surface.

Further, Patent Document 3 below proposes a method for obtaining a scratching effect by blending a powder containing a cellulose substance, and Patent Document 4 listed below pulverizes seed shells and fruit nuclei. A method of blending vegetable powder has been proposed.
JP-A-62-283001. JP 2000-158907 A. JP 2000-129038 A. Japanese Patent Application Laid-Open No. 10-7841.

  According to the above conventional technique, although the effect of improving the performance on ice can be obtained, there is a problem that the wear resistance is deteriorated.

  This invention is made | formed in view of the above point, and it aims at providing the rubber composition and pneumatic tire which can improve performance on ice, without deteriorating abrasion resistance.

The rubber composition according to the present invention is 0.5 to 20 weight percent of a powder having an average particle size of 100 to 300 μm made of melamine foam, which is a foam of melamine resin, with respect to 100 weight parts of a rubber component made of diene rubber. It is characterized by partly blending. Moreover, the pneumatic tire of the present invention uses such a rubber composition for a tread.

  According to the present invention, by blending powder of melamine foam, excellent grip performance on ice is exhibited by the three-dimensional network structure unique to melamine foam, and deterioration of wear resistance can be suppressed.

  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 used as the rubber component, various diene rubbers usually used as a rubber composition for tires can be used. For example, natural rubber, styrene butadiene rubber, butadiene Examples thereof include rubber and isoprene rubber. In particular, a blend of natural rubber and another diene rubber is preferable.

  In the rubber composition of the present invention, melamine foam powder is blended with the rubber component. Melamine foam is a melamine resin foam obtained by the reaction of melamine and formaldehyde, and is prepared by blending the foaming agent component with melamine and formaldehyde, or their precondensates, which are the main raw materials, and foaming and curing. Can do. In addition to the above melamine and formaldehyde, other monomers such as urea and phenol may be added as a monomer constituting the melamine resin.

  The melamine foam powder is obtained by pulverizing the melamine foam thus obtained into a powder using a known pulverizer such as a roll, and selecting and classifying the powder into a predetermined particle size range.

  Melamine foam generally has a three-dimensional network structure consisting of a thin fibrous cell skeleton, which exhibits unique elastic properties in rubber, which improves the grip performance on ice and improves braking performance on ice. Performance on ice such as improves. This is thought to be due to the melamine foam powder exposed on the rubber surface sticking to the road surface on ice due to the elastic characteristics resulting from the above-mentioned unique three-dimensional network structure. In addition, melamine foam is harder than general urethane foam, and due to its moderate elasticity, it is considered that the strain applied locally can be dispersed and the stress can be relieved at the time of ground contact, thereby reducing wear resistance. Can be prevented from worsening. In addition, the melamine foam itself is hydrophilic because the melamine resin itself is hydrophilic, so it has an excellent adsorption effect on the road surface on ice, and since the melamine resin is also excellent in heat resistance, deterioration and deformation due to temperature during vulcanization molding Etc. can also be suppressed.

  The average particle size of the melamine foam powder is 100 to 300 μm. If the average particle size is smaller than this, the effect on braking performance on ice is insufficient, and if it exceeds the above range, the wear resistance tends to deteriorate. The average particle size is a value measured with a laser diffraction particle size distribution measuring device.

  The melamine foam powder is blended in an amount of 0.5 to 20 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the rubber component. If the blending amount is less than the above range, the effect on braking performance on ice is insufficient, and if it exceeds the above range, the wear resistance tends to deteriorate.

  The rubber composition of the present invention preferably contains vegetable powder together with the melamine foam powder. By using melamine foam powder and vegetable powder in combination, the braking effect on the road surface on ice is further enhanced by the effect of improving grip due to the elastic properties of the powder of melamine foam and the effect of digging up the vegetable powder. Can be improved.

  As such vegetable powder, a seed shell such as walnuts or walnuts having a Mohs hardness of 2 or more, or a fruit core such as peach or plum, which is harder than the hardness of ice, is known by a known method. Examples include pulverized products obtained by pulverization. The particle size of the vegetable powder is not particularly limited, but a powder of 100 to 600 μm is preferably used. When the thickness is less than 100 μm, when used for a tread, the protrusion formed on the tread may be reduced, and the scratching effect may be reduced. On the other hand, if it exceeds 600 μm, the number for a constant weight decreases and the number of protrusions decreases, which may reduce the scratching effect.

  Further, as the vegetable powder, in order to improve the compatibility with rubber and prevent the vegetable powder from falling off, a powder treated with a rubber adhesion improver may be used, or the surface-treated powder may be used. It is also possible to use a mixture of a solid and a non-surface-treated one. Preferred examples of the rubber adhesion improver include those mainly composed of a mixture of resorcin / formalin resin initial condensate and latex (RFL liquid). The mixture is obtained by, for example, dissolving both in water at a ratio of 1 to 2 mol of formalin or hexamethylene aldehyde with respect to 1 mol of resorcin, and aging by adding a small amount of caustic soda or caustic potash aqueous solution. The initial condensate is added to and mixed with natural rubber latex or diene rubber latex or a mixture of both at a ratio of 10 to 80 parts by weight with respect to 100 parts by weight of latex in terms of solid content.

  The vegetable powder is preferably added in an amount of 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the diene rubber. If the blending amount is less than the above range, the digging effect is small, and conversely if too large, the wear resistance tends to deteriorate.

  In addition to the components described above, the rubber composition of the present invention includes reinforcing fillers such as carbon black and silica, silane coupling agents, anti-aging agents, zinc white, stearic acid, softeners, vulcanizing agents, vulcanizing agents, Various additives generally used in a tire tread rubber composition such as a sulfur accelerator can be blended.

  The rubber composition of the present invention as described above is suitably used as a rubber composition for a tread portion of a studless tire, and the tread portion can be formed by vulcanization molding according to a conventional method. And if it is a tread part which consists of this rubber composition, the braking performance on ice can be improved, maintaining abrasion resistance by mix | blending the powder of melamine foam.

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

  Using a Banbury mixer, a tread rubber composition for studless tires was prepared according to the formulation shown in Table 1 below. Each component in Table 1 is as follows.

・ Natural rubber: RSS No. 3,
-Butadiene rubber: High butadiene rubber "BR01" manufactured by JSR,
・ Carbon black: Carbon black N339 "Seast KH" made by Tokai Carbon,
・ Silica: Nippon Silica “Nip Seal AQ”
Silane coupling agent: Degussa “Si69”,
Paraffin oil: “Process P200” manufactured by JOMO.

・ Melamine foam powder 1: melamine foam ("Beppin-san" manufactured by Mock Co., Ltd.) is pulverized through a roll and sieved to obtain an average particle size of 180 µm (average particle size is Shimadzu Corporation) Measured with a particle size distribution measuring apparatus “SALV-2000A” manufactured by the same manufacturer.

Melamine foam powder 2: A powder having an average particle size of 250 μm obtained by pulverizing melamine foam (Mr. Beppin, manufactured by Mock Co., Ltd.) through a roll and sieving it.

Melamine foam powder 3: A powder having an average particle size of 50 μm obtained by pulverizing melamine foam (Mr. Bockpin, manufactured by Mock Co., Ltd.) through a roll and sieving it.

Melamine foam powder 4: A powder having an average particle diameter of 500 μm obtained by pulverizing melamine foam (“Beppin-san” manufactured by Mock Co., Ltd.) through a roll and sieving it.

Plant powder: ground walnut shell ("Soft Grip # 46" manufactured by Walnut Japan, surface-treated with RFL treatment liquid. The average particle size of the treated plant granules is 300 μm.

Cellulose fine powder: A powder having an average particle size of 250 μm obtained by pulverizing pulp using a ball mill and sieving it with a sieve.

-Urethane foam powder: A powder having an average particle size of 250 μm obtained by roughly pulverizing urethane foam using a 10-inch roll, then pulverizing it into a fine powder with a 6-inch roll, and sieving and classifying. . The urethane foam was blended into 40 parts by weight of polyether polyol (“EP-3033” manufactured by Mitsui Takeda Chemical Co., Ltd.), 60 parts by weight of polymer polyol (“POP34-28” manufactured by Mitsui Takeda Chemical Co., Ltd.), and a crosslinking agent (“DEA manufactured by Mitsui Takeda Chemical Co., Ltd.). "1 part by weight, 4 parts by weight of a cross-linking agent (Daiichi Kogyo Seiyaku" Hardmaster 17 "), 1 part by weight of a foam stabilizer (" SRX-274C "manufactured by Toray Dow Corning Silicon), catalyst (" Sankyo Air Products " DABCO33LV ") 0.4 parts by weight, catalyst (UCA" NiaxA-1 ") 0.1 parts by weight, and water 3.6 parts by weight.

  In each rubber composition, as a common compound, 2 parts by weight of stearic acid (“Lunac S-20” manufactured by Kao), 100% of rubber component, zinc white (“Zinc Hana 1 type” manufactured by Mitsui Metals) 3 Parts by weight, anti-aging agent (“Antigen 6C” manufactured by Sumitomo Chemical), 2 parts by weight of wax (“OZOACE0355” manufactured by Nippon Seiki), 2.1 parts by weight of sulfur (“powder sulfur” manufactured by Tsurumi Chemical) 1.5 parts by weight of a sulfur accelerator (“Soccinol CZ” manufactured by Sumitomo Chemical) was blended.

  The hardness of each rubber composition obtained was measured. Also, studless tires were prepared using each rubber composition, and the braking performance (ice braking performance) and wear resistance on the road surface on ice were evaluated. The tire size was 185 / 65R14, and each rubber composition was applied to the tread and vulcanized and molded according to a conventional method. Each rim used was 14 × 5.5 JJ. Each measurement / evaluation method is as follows.

Hardness: Conforms to JIS K7215.

・ Ice braking performance: The above tire is mounted on a 2000cc FF vehicle, and the braking distance is measured by running an ABS from 40km / h on an icy road (-5 ± 3 ° C) (average value of n = 10). The index was expressed as an index with Comparative Example 1 as 100. The larger the index, the shorter the braking distance and the better the braking performance.

Abrasion resistance: The above tire is mounted on a 2000 cc FF vehicle, rotated back and forth every 2500 km, and the remaining grooves after running 10,000 km (average value of remaining grooves of four tires) were measured. The value was expressed as an index with a value of 100. A larger index indicates better wear resistance.

  The results are as shown in Table 1. In Examples 1 to 5 according to the present invention, the braking performance on ice was greatly improved as compared with Comparative Example 1 as a control. Further, in these examples, in contrast to Comparative Example 1 in which melamine foam powder, which is a foreign matter for rubber, is blended to improve performance on ice, such powder is not blended. The same or better wear resistance was ensured. In contrast, Comparative Examples 6 and 7 improved the braking performance on ice, but were inferior to melamine foam powder.

  Since the rubber composition according to the present invention can improve the braking performance on ice while maintaining the wear resistance, it can be suitably used as a rubber constituting a tread of a pneumatic tire starting from a studless tire.

Claims (3)

A rubber characterized in that 0.5 to 20 parts by weight of a powder having an average particle size of 100 to 300 μm made of melamine foam, which is a foam of melamine resin, is blended with 100 parts by weight of a rubber component made of diene rubber. Composition. The rubber composition according to claim 1, comprising 0.5 to 20 parts by weight of vegetable powder obtained by pulverizing seed shells or fruit nuclei with respect to 100 parts by weight of the rubber component .   A pneumatic tire using the rubber composition according to claim 1 or 2 for a tread.