JP2006282806A - Rubber composition for tire, and studless tire made from the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for tires to be used for studless tires with improved on-ice performance, and to provide such a studless tire made from the composition. <P>SOLUTION: The rubber composition comprises comprises a rubber component comprising 5-30 wt.% of a halogenated rubber and 95-70 wt.% of a diene rubber and calcium carbonate-based particles. The studless tire made from the composition is also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rubber composition for tires and a studless tire comprising the same.

  Spike tires have been used on snowy roads, and chains have been attached to tires. However, environmental problems such as dust have occurred, and studless tires have been developed as alternative snowy road tires. Various studies have been made to improve the performance on ice (starting performance, acceleration performance, and braking performance of a tire on an icy and snowy road surface).

  For example, in order to remove water generated on an icy and snowy road surface that causes slipping, it has been practiced to add foamed rubber or a balloon to a rubber composition for tires.

  In addition, solid foreign matters (for example, non-metallic fibers, walnuts, etc.) have been blended into the tread of a studless tire.

  However, these methods cannot be said to sufficiently improve the on-ice performance of studless tires on icy and snowy road surfaces.

  Further, Patent Document 1 discloses a tire rubber composition using a halogenated rubber as a rubber component. However, the performance on ice is still insufficient, and further improvement is required.

JP 2005-15570 A

  An object of the present invention is to provide a tire rubber composition used for a studless tire with improved performance on ice and a studless tire comprising the same.

  The present invention relates to a rubber composition for tires containing a rubber component comprising 5 to 30% by weight of a halogenated rubber and 95 to 70% by weight of a diene rubber, and calcium carbonate particles.

  Furthermore, it is preferable that carbon black and silica are contained as the reinforcing filler, and the content of silica in the reinforcing filler is 5 to 20% by weight.

  The calcium carbonate particles are preferably eggshell powder.

  The average particle diameter of the calcium carbonate-based particles is 1 to 50 μm, and the content thereof is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the rubber component.

  The present invention also relates to a studless tire made of the tire rubber composition.

  According to the present invention, by blending a specific amount of halogenated rubber and calcium carbonate-based particles, while maintaining wear resistance, it exhibits a sufficient water absorption effect and scratching effect on the icy and snowy road surface. Thus, it is possible to provide a tire rubber composition having improved adhesion and a studless tire comprising the same.

  The tire rubber composition of the present invention comprises a rubber component and calcium carbonate-based particles.

  The rubber component is composed of a diene rubber and a halogenated rubber.

  Examples of the diene rubber include natural rubber (NR), isoprene rubber (IR), styrene butadiene rubber (SBR), and polybutadiene rubber (BR). Among these, NR and / or BR are preferable as the diene rubber because the wear resistance can be maintained at a high level and the heat generation performance is good.

  The content of the diene rubber in the rubber component is 70% by weight or more. When the content of the diene rubber is less than 70% by weight, the rubber processability, rubber strength and wear resistance are reduced. Further, the content of the diene rubber in the rubber component is 95% by weight or less. When the content of the diene rubber exceeds 95% by weight, the effect of improving the adhesion of the rubber composition to ice is remarkably reduced.

  When NR is used as the diene rubber, the content of NR in the rubber component is preferably 40 to 80% by weight. If the NR content in the rubber component is less than 40% by weight, the heat generation performance tends to be reduced, and if the NR content exceeds 80% by weight, the wear resistance and on-ice performance tend to be reduced. .

  Moreover, when using BR as a diene rubber, it is preferable that the content rate of BR in a rubber component is 20 to 60 weight%. If the BR content in the rubber component is less than 20% by weight, the wear resistance and on-ice performance tend to be reduced, and if the BR content exceeds 60% by weight, the heat generation performance tends to be reduced. .

  Specific examples of the halogenated rubber include halogenated butyl rubber and halogenated copolymer rubber obtained by halogenating isobutylene-p-methylstyrene copolymer rubber, such as brominated polyisobutylene-p-methylstyrene (Exxpro 3745). can give.

  The content of the halogenated rubber in the rubber component is 5% by weight or more, preferably 10% by weight or more. If the content of the halogenated rubber is less than 5% by weight, tan δ near 0 ° C. cannot be sufficiently improved, so that the performance on ice is not improved. The content of the halogenated rubber in the rubber component is 30% by weight or less, preferably 20% by weight or less, and more preferably 15% by weight or less. When the content of the halogenated rubber exceeds 30% by weight, the wear resistance is lowered, and the glass transition temperature of the rubber composition is increased, so that the performance on ice is also lowered.

  By blending the calcium carbonate-based particles with the rubber composition for tires having a specific rubber component, (1) the calcium carbonate-based particles themselves scratch the ice and snow road surface, and (2) the fine particles present in the calcium carbonate-based particles. The effect that the hole absorbs and removes water on the snowy and snowy road surface, (3) The effect that the pore formed by the removal of calcium carbonate-based particles absorbs and removes the water on the snowy and snowy road surface, and (4) The effect of (1) to (4), which is the effect of scratching the snowy and snowy road surface, is obtained when the ridges of the pores formed by dropping off act as edges. Thus, the improvement in performance on ice is largely due to the effect of removing moisture by the pores obtained by dropping off the pores existing in the calcium carbonate particles or the calcium carbonate particles, in addition to the scratch effect. .

  As the calcium carbonate-based particles, commercially available particles can be used, but calcium carbonate-based particles obtained from a living body (biologically derived calcium carbonate-based particles) are particularly preferable.

  Examples of the calcium carbonate-based particles derived from a living body include eggshell powder (for example, chicken egg powder). Of these, eggshell powder is preferable as the biologically derived calcium carbonate-based particle because it can be supplied in a large amount and can be obtained at the lowest cost.

  The average particle diameter of the calcium carbonate-based particles is preferably 1 μm or more, and more preferably 5 μm or more. When the average particle diameter is less than 1 μm, there is a tendency that pores due to dropping of calcium carbonate-based particles cannot be obtained sufficiently. The average particle size of the calcium carbonate-based particles is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 15 μm or less. When the average particle size exceeds 50 μm, there is a tendency that a sufficient number of pores cannot be obtained on the surface of the rubber composition.

  The content of the calcium carbonate-based particles is preferably 5 parts by weight or more and more preferably 10 parts by weight or more with respect to 100 parts by weight of the rubber component. When the content of the calcium carbonate particles is less than 5 parts by weight, a sufficient number of pores cannot be obtained on the surface of the rubber composition. Further, the content of the calcium carbonate-based particles is preferably 30 parts by weight or less, more preferably 25 parts by weight or less, and further preferably 20 parts by weight or less with respect to 100 parts by weight of the rubber component. . When the content of calcium carbonate particles exceeds 30 parts by weight, the wear resistance tends to decrease.

  In addition to the rubber component and calcium carbonate particles, a reinforcing filler can be blended in the rubber composition for tires of the present invention.

  Examples of the reinforcing filler include carbon black and silica.

  The tire rubber composition of the present invention preferably contains carbon black and silica together with the halogenated rubber. At that time, it is preferable that the rubber composition is blended so that the hardness thereof is constant. When doing so, the effects of addition thereof are synergized, and tan δ around 0 ° C. can be greatly improved.

  The compounding amount of carbon black is preferably 30 to 50 parts by weight with respect to 100 parts by weight of the rubber component. When the blending amount of carbon black is less than 30 parts by weight, the rubber hardness tends to decrease and the wear resistance tends to decrease. On the other hand, when the blending amount of carbon black exceeds 50 parts by weight, the rubber hardness becomes excessively high and the heat generation performance tends to be lowered.

  By containing silica together with the halogenated rubber, tan δ near 0 ° C. of the rubber composition can be greatly improved, and tan δ near 70 ° C. can be further reduced. By reducing tan δ around 70 ° C., it is possible to suppress heat generation that causes tire damage.

  It is preferable that the compounding quantity of a silica is 5-20 weight part with respect to 100 weight part of rubber components. If the blending amount of silica is less than 5 parts by weight, the effect of suppressing heat generation tends to be insufficient. Moreover, when the compounding quantity of silica exceeds 20 weight part, there exists a tendency for abrasion resistance to fall.

  The weight ratio of silica to the weight of the total reinforcing filler (the silica content in the reinforcing filler) is preferably 5 to 20% by weight. When the content of silica is less than 5% by weight, the effect of blending silica tends to be insufficient. Moreover, when the content rate of silica exceeds 20 weight%, there exists a tendency for abrasion resistance to fall large.

  In addition to the rubber component, calcium carbonate-based particles and reinforcing filler, the tire rubber composition of the present invention includes an antioxidant, wax, stearic acid, zinc oxide, sulfur, a vulcanization accelerator, and the like for tires. Additives generally blended in the rubber composition can be blended as appropriate.

  In the studless tire of the present invention, an unvulcanized rubber composition obtained by kneading the rubber component, calcium carbonate-based particles and reinforcing filler, and, if necessary, the above additives into a tread shape of the studless tire. The unvulcanized tire is formed on a tire molding machine, and the unvulcanized tire is heated and pressurized in the vulcanizer.

  The studless tire of the present invention is particularly preferably used for heavy-duty vehicles (buses, trucks, etc.).

  The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

The various chemicals used in the examples are described below.
NR: RSS # 3
BR: BR150B manufactured by Ube Industries, Ltd.
EXXPRO: EXXPRO 3745 (brominated product of isobutylene-p-methylstyrene copolymer rubber) manufactured by ExxonMobil Co., Ltd.
Eggshell powder 1: manufactured by Kewpie Co., Ltd. (average particle size: 10 μm)
Eggshell powder 2: manufactured by Kewpie Co., Ltd. (average particle size: 50 μm)
Calcium carbonate: HT020 manufactured by Hitachi Crushed Stone Co., Ltd. (average particle size: 2 μm)
Carbon black: Diamond Black I (N110) manufactured by Mitsubishi Chemical Corporation
Silica: Nipsil VN3 manufactured by Degussa Japan
Wax: Sannoc Wax anti-aging agent manufactured by Ouchi Shinsei Chemical Industry Co., Ltd .: Ozonon 6C manufactured by Seiko Chemical Co., Ltd.
Stearic acid: Tungsten zinc oxide manufactured by Nippon Oil & Fats Co., Ltd .: Ginseng R manufactured by Toho Zinc Co., Ltd.
Sulfur: Sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Examples 1-6 and Comparative Examples 1-12
<Method for manufacturing studless tire>
Chemicals other than sulfur and a vulcanization accelerator were added according to the blending amounts shown in Tables 1 to 3, and kneaded at about 150 ° C. for 5 minutes with a Banbury mixer. Thereafter, sulfur and a vulcanization accelerator were added to the obtained kneaded material according to the blending amounts shown in Tables 1 to 3, and kneaded with a biaxial open roll at about 80 ° C. for 5 minutes to obtain an unvulcanized rubber composition. Got. The obtained unvulcanized rubber composition is molded into a tread shape, bonded to another tire member, and vulcanized at 150 ° C. and 25 kgf for 35 minutes to obtain a studless tire for a truck / bus (tire size) : 11R22.5) and used for the following tests.

<Test method>
(Performance on ice)
Studless tires were mounted on a 4-ton car, and at the Hokkaido Asahikawa Test Course, the brake brake was applied at a speed of 30km / h at a temperature of -1 to -6 ° C, and the stopping distance on ice required for the car to stop was measured. . In addition, the vehicle was used to measure start, acceleration, and stop, and evaluated by feeling. Moreover, the reciprocal number of the said stop distance was each taken, the reciprocal number of the comparative example 1 was set to 100, and the other reciprocal number was represented by the index | exponent. In addition, the evaluation by the feeling of starting, accelerating and stopping was based on Comparative Example 1 as 100, and 120 was determined by the test driver that the performance was clearly improved. And the performance index on ice was computed by averaging the index of the reciprocal of stop distance, and the value of evaluation by feeling. A larger index indicates better performance on ice.

(Abrasion resistance)
A 5 mm thick test piece was cut out from the tread of the studless tire, and the slip rate was measured at a surface rotation speed of 50 m / min, a load load of 3.0 kg, and a sandfall amount of 15 g / min using a Lambone abrasion tester manufactured by Iwamoto Seisakusho Co., Ltd. The amount of wear was measured at 20%, and the reciprocal of the amount of wear was taken. And the reciprocal number of the abrasion amount of the comparative example 1 was set to 100, and the reciprocal number of the other abrasion amount was represented by the index | exponent. It shows that it is excellent in abrasion resistance, so that an index | exponent is large.

(Viscoelasticity test)
A test piece having a thickness of 2 mm was cut out from the tread of the studless tire, and the loss tangent tan δ at 70 ° C. was measured with a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under the conditions of a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of 2%. The loss tangent tan δ at 0 ° C. was measured. It shows that heat_generation | fever of a rubber composition is suppressed, so that the value of tan-delta in 70 degreeC is small. In addition, the larger the value of tan δ at 0 ° C., the better the adhesion of rubber to the snowy and snowy road surface.

(hardness)
Using a JIS-A hardness meter, the hardness of the test piece cut out from the studless tire was measured under the measurement condition of 0 ° C.

  Test results are shown in Tables 1-3.

Claims (5)

A tire rubber composition comprising a rubber component comprising 5 to 30% by weight of a halogenated rubber and 95 to 70% by weight of a diene rubber, and calcium carbonate particles. The tire rubber composition according to claim 1, further comprising carbon black and silica as a reinforcing filler, wherein the silica content in the reinforcing filler is 5 to 20% by weight. The tire rubber composition according to claim 1 or 2, wherein the calcium carbonate-based particles are eggshell powder. The tire rubber composition according to claim 1, 2 or 3, wherein the calcium carbonate-based particles have an average particle diameter of 1 to 50 µm and a content of 5 to 30 parts by weight with respect to 100 parts by weight of the rubber component. A studless tire comprising the rubber composition for a tire according to claim 1, 2, 3 or 4.