JP2005272602A - Rubber composition for tire and pneumatic tire using the rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for tires improved in on-ice frictional performance, and to provide a pneumatic tire using the rubber composition for its tread. <P>SOLUTION: The rubber composition for tires comprises 100 pts.wt. of a diene rubber, 0.5-30 pts.wt. of a filler having two or more projections and 0.5-20 pts.wt. of porous natural glass. The pneumatic tire made from this rubber composition is also provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a tire rubber composition and a pneumatic tire, and more particularly to a tire rubber composition having excellent frictional performance on ice and a pneumatic tire using the same.

  Spike tires have been used on snowy roads, and chains have been attached to tires. However, environmental problems such as dust problems have occurred, and studless tires have been developed as alternative snowy road tires. It was.

  Since the snowy and snowy road surface has a significantly lower coefficient of friction than the general road surface and is slippery, the studless tire has been devised in terms of material and design. For example, rubber compositions containing diene rubbers with excellent low-temperature characteristics have been developed, and surface edge components can be increased by changing the unevenness of the tire surface, or natural glass with a scratching effect can be added (patent document) 1)), etc., to improve the performance on ice by obtaining a scratching effect on ice on an icy and snowy road surface.

  However, even with the studless tire as described above, the friction performance on the icy and snowy road surface is still insufficient as compared with the spiked tire, and further improvement is required.

JP 2002-53704 A

  An object of the present invention is to provide a rubber composition for tires having improved friction performance on ice, and a pneumatic tire using the rubber composition for a tire tread.

  The present invention relates to a tire rubber composition containing 0.5 to 30 parts by weight of a filler having two or more protrusions and 0.5 to 20 parts by weight of porous natural glass with respect to 100 parts by weight of a diene rubber. About.

  The tire rubber composition further has an average fiber diameter of 1 to 100 μm and an average fiber length of 0.1 to 5 mm, based on 100 parts by weight of diene rubber, and 0.5 to 20 nonmetallic fibers. It is preferable to contain a weight part.

In the tire rubber composition, when the compounding amounts of the non-metallic fiber, the filler having two or more protrusions and the porous natural glass are X, Y and Z, respectively, the formula:
2X + Y + 2Z ≦ 30
It is preferable to satisfy.

  The present invention also relates to a pneumatic tire comprising the tire rubber composition.

  According to the present invention, by blending a diene rubber with a filler having two or more protrusions, a water film generated between the tire and the icy and snowy road surface is eliminated, and the icy and snowy road surface is scratched. In addition, by blending porous natural glass, when the glass is on the rubber surface, the glass scratches the snowy snow road surface, and after it falls off, due to the water-repellent effect of micro unevenness on the rubber surface, The water film generated between the tire and the icy and snowy road surface is removed. Furthermore, by mixing non-metallic fibers, the snowy and snowy road surface is scratched. Therefore, it is possible to obtain a studless tire having excellent frictional performance on ice without using a special technique (apparatus) in manufacturing the tire. Furthermore, by specifying the blending amounts of the above-mentioned three kinds of materials, it is possible to achieve both on-ice friction performance and wear resistance.

  The rubber composition for tires of the present invention contains a diene rubber as a rubber component.

  Any diene rubber is used as the diene rubber. For example, natural rubber (NR), polyisoprene rubber (IR), various polybutadiene rubbers (BR), various styrene-butadiene copolymer rubbers (SBR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), Diene rubbers such as halogenated butyl rubber and polychloroprene (CR) can be used alone or blended at an arbitrary ratio.

  The rubber composition for tires of the present invention contains a filler having two or more protrusions. By blending a filler having two or more protrusions, the two or more protrusions show an anchor effect, prevent falling off due to irritation and wear during running, and make micro protrusions appear from the rubber surface. An effect of eliminating a water film generated between tires and a micro scratching effect are exhibited. Moreover, in this invention, when a filler is mix | blended with the said rubber component, it shows the effect excellent in abrasion resistance, heat resistance, thermal conductivity, etc.

  The number of protrusions of the filler is 2 or more, preferably 3 or more. In a filler having no protrusion or having only one protrusion, the filler cannot show an anchor effect, and the filler falls off due to stimulation or wear due to tire running or the like.

  Examples of the filler include zinc oxide whiskers (for example, Panatetra (tetrapot-shaped zinc oxide) manufactured by Matsushita Amtech Co., Ltd.) and star sand produced in Okinawa Prefecture. Of these, zinc oxide whiskers are preferably used because they are harder than ice and softer than asphalt.

  The length of needle-like short fibers of the filler is preferably 1 μm or more, more preferably 10 μm or more. When the length of the needle-like short fiber of the filler is less than 1 μm, there is a tendency that the improvement of the on-ice friction performance on the snowy and snowy road surface is not observed. In addition, the needle-like short fiber length of the filler is preferably 5000 μm or less, more preferably 1000 μm or less. When the needle-like short fiber length of the filler exceeds 5000 μm, the wear resistance tends to be remarkably lowered.

  The needle-like short fiber diameter (average value) of the filler is preferably 0.5 μm or more. If the diameter of the needle-like short fiber of the filler is less than 0.5 μm, a sufficient scratching effect cannot be obtained, and the friction performance on ice tends not to be improved. The needle-like short fiber diameter of the filler is preferably 2000 μm or less, more preferably 200 μm or less. When the needle-like short fiber diameter of the filler exceeds 2000 μm, the wear resistance tends to be remarkably lowered.

  The blending amount of the filler is 0.5 parts by weight or more, preferably 1 part by weight or more, more preferably 5 parts by weight or more with respect to 100 parts by weight of the diene rubber. When the blending amount of the filler is less than 0.5 part by weight, the improvement of the on-ice friction performance on the icy and snowy road surface is not observed. Moreover, the compounding quantity of the said filler is 30 weight part or less, Preferably it is 25 weight part or less, More preferably, it is 10 weight part or less. When the blending amount of the filler exceeds 30 parts by weight, the wear resistance decreases.

  In order to improve the adhesive force between the filler and the diene rubber, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PU), polyvinyl alcohol (PVA), silane coupling agent and silyl The filler may be surface treated with an agent.

  Furthermore, the rubber composition of the present invention contains porous natural glass (silicon oxide). By blending porous natural glass, it has a scratching effect when natural glass is present on the rubber surface, and after falling off, drains water by creating micro unevenness, improving the frictional force on ice .

  Examples of the porous natural glass include shirasu balloon made from shirasu and artificial soil.

  The average particle diameter of the porous natural glass is preferably 1 μm or more, more preferably 50 μm or more. If the average particle size is less than 1 μm, the scratching effect is insufficient, and the unevenness after the glass is pulled out is too small, so that the drainage effect tends to be insufficient. The average particle size of the porous natural glass is preferably 250 μm or less, more preferably 200 μm or less. If the average particle diameter exceeds 250 μm, the strength of the rubber tends to decrease and the wear resistance tends to deteriorate.

  The average pore diameter of the porous natural glass is preferably 50 μm or less, more preferably 10 μm or less. If the average pore diameter exceeds 50 μm, the particles tend to be destroyed when kneaded into rubber, so that the scratching effect and the drainage effect due to unevenness tend not to be sufficiently obtained.

  The compounding amount of the porous natural glass is 0.5 parts by weight or more, preferably 1 part by weight or more with respect to 100 parts by weight of the diene rubber. When the amount of the porous natural glass is less than 0.5 parts by weight, the scratching effect and the drainage effect due to the unevenness after the glass falls off cannot be sufficiently obtained. Moreover, the compounding quantity of porous natural glass is 20 weight part or less, Preferably it is 10 weight part or less. When the amount of the porous natural glass exceeds 20 parts by weight, the strength of the rubber is lowered and the wear resistance is deteriorated.

  Furthermore, the rubber composition for tires of the present invention preferably contains non-metallic fibers. By blending non-metallic fibers, a micro scratching effect on ice on the snowy and snowy road surface is expressed.

  Normally, non-metallic fibers in rubber extruded by a calender roll are oriented in the extrusion direction. Therefore, in order to effectively develop the effect of scratching the ice by the fibers, the sheet is produced in the extrusion direction as a manufacturing method thereof. Vertically cut and stand up, or by making the extrusion head into a tube shape, orient the fibers in a direction perpendicular to the extrusion direction, cut the sheet parallel to the extrusion direction, and rotate each by 90 degrees It was necessary to use a special technique (apparatus) such as aligning in the thickness direction of the tread by overlapping again. However, in the present invention, non-metallic fibers are blended with rubber together with the filler having the two or more protrusions to disturb the fiber orientation in the rubber extrusion direction. ), The effect of scratching the ice by non-metallic fibers can be sufficiently obtained.

  The non-metallic fiber has no fear of damaging the road surface, has a small difference between rubber and wear speed, and is suitable for ensuring the contact between the tire and the icy / snowy road surface. Of the non-metallic fibers, non-metallic inorganic fibers are preferable. Further, glass fibers or carbon fibers that are broken to an appropriate length in the process of kneading rubber are preferable because they are easy to disperse and orient, and rubber having an appropriate ratio of complex elastic modulus is easily obtained.

  The average fiber diameter of the non-metallic fiber is preferably 1 μm or more, more preferably 3 μm or more. When the average fiber diameter is less than 1 μm, the fiber cross-sectional area is small, and thus fibers oriented in the thickness direction tend not to be able to sufficiently create a portion with a high contact pressure on the rubber surface. The average fiber diameter is preferably 100 μm or less, more preferably 50 μm or less, and particularly preferably 40 μm or less. When the average fiber diameter is larger than 100 μm, the function of pushing off the water film generated between the snowy and snowy road surface and the tire is inferior, so that there is a tendency that adhesion and adhesion friction do not work sufficiently.

  The average fiber length of the non-metallic fiber is preferably 0.1 mm or more. When the average fiber length is shorter than 0.1 mm, the fiber tends to drop off from the rubber surface by running, and the effect of pushing off the water film tends to decrease. The average fiber length is preferably 5 mm or less, more preferably 3 mm or less. When the average fiber length is longer than 5 mm, it becomes difficult to disperse and orient the fibers, and the processability of rubber tends to decrease.

  The compounding amount of the non-metallic fiber is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more with respect to 100 parts by weight of the diene rubber. If the blending amount of the non-metallic fibers is less than 0.5 parts by weight, the amount of fibers that form a contact pressure on the rubber surface decreases, and there is a tendency that the effect of removing the water film and scratching ice cannot be obtained sufficiently. The blending amount of the nonmetallic fiber is preferably 20 parts by weight or less, more preferably 18 parts by weight or less, and particularly preferably 15 parts by weight or less. If the blending amount of the non-metallic fiber exceeds 20 parts by weight, the rigidity becomes too high and the rubber surface cannot follow the icy and snowy road surface, and the adhesion / adhesion friction tends to decrease.

The blending amounts of the non-metallic fiber, filler and porous natural glass are represented by the formula:
2X + Y + 2Z ≦ 30
It is preferable to satisfy. By specifying the blending amount in this way, it is possible to achieve both friction performance on ice and wear resistance. When (2X + Y + 2Z) exceeds 30, there is a tendency that the friction performance on ice and the wear resistance cannot be made compatible. More preferably, (2X + Y + 2Z) is 25 or less.

  In the tire rubber composition of the present invention, in addition to the rubber component, filler, porous natural glass, and non-metallic fibers, other reinforcing agents (fillers), vulcanizing agents (crosslinking agents), and vulcanization acceleration. Various compounding agents and additives blended for tires or general rubber compositions such as agents, various oils, anti-aging agents, softeners, plasticizers, and coupling agents can be blended. Moreover, the compounding quantity of these compounding agents and additives can also be made into a general quantity.

Examples of the reinforcing agent include silica and / or an inorganic filler represented by the general formula (1).
mM · xSiOy · zH ₂ O (1)
(M is at least selected from metals selected from the group consisting of aluminum, magnesium, titanium, calcium and zirconium, oxides and hydroxides of the metals, and hydrates thereof, and carbonates of the metals. 1 and m, x, y and z are constants.)

  The compounding amount of the inorganic filler is preferably 150 parts by weight or less, more preferably 100 parts by weight or less, with respect to 100 parts by weight of the diene rubber. If the blending amount of the inorganic filler exceeds 150 parts by weight, processability tends to be impaired. Moreover, it is preferable that the compounding quantity of an inorganic filler is 5 weight part or more.

  When silica is blended, it is preferable to use a silane coupling agent in combination. The compounding amount of the silane coupling agent is preferably 1 part by weight or more, more preferably 2 parts by weight or more with respect to 100 parts by weight of the silica. When the amount of the silane coupling agent is less than 1 part by weight, the viscosity of the unvulcanized rubber composition tends to be high. Moreover, the compounding quantity of a silane coupling agent becomes like this. Preferably it is 20 weight part or less with respect to 100 weight part of said silica, More preferably, it is 15 weight part or less. Moreover, when the compounding quantity of a silane coupling agent exceeds 20 weight part, there exists a tendency for the effect which mix | blended the silane coupling agent instead of the compounding quantity is small, and cost starts.

  Moreover, carbon black is mention | raise | lifted as said reinforcing agent. The compounding amount of carbon black is preferably 5 parts by weight or more, more preferably 10 parts by weight or more with respect to 100 parts by weight of the diene rubber. When the blending amount of carbon black is less than 5 parts by weight, sufficient reinforcing properties cannot be obtained, and wear resistance tends to be inferior. The blending amount of carbon black is preferably 150 parts by weight or less, more preferably 100 parts by weight or less. When the blending amount of the carbon black exceeds 150 parts by weight, the workability becomes poor and the hardness increases, so that the friction performance on ice tends to be lowered.

  When the oil is blended, the blending amount of the oil is preferably 5 parts by weight or more, more preferably 10 parts by weight or more with respect to 100 parts by weight of the diene rubber. When the blending amount of oil is less than 5 parts by weight, the hardness is not lowered and the friction performance on ice tends to be lowered. The blending amount of oil is preferably 150 parts by weight or less, more preferably 100 parts by weight or less. When the amount of oil exceeds 150 parts by weight, the wear resistance tends to decrease.

  An example of the vulcanizing agent is sulfur. The compounding amount of sulfur is preferably 0.2 parts by weight or more, more preferably 0.5 parts by weight or more with respect to 100 parts by weight of the diene rubber. When the amount of sulfur is less than 0.2 parts by weight, the crosslinking density is low and the strength tends not to be obtained. The amount of sulfur is preferably 10 parts by weight or less, more preferably 4 parts by weight or less. When the amount of sulfur exceeds 10 parts by weight, the friction performance on ice tends to decrease due to the increase in hardness as the crosslinking density increases.

  When the vulcanization accelerator is blended, the blending amount of the vulcanization accelerator is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more with respect to 100 parts by weight of the diene rubber. When the blending amount of the vulcanization accelerator is less than 0.1 parts by weight, the vulcanization speed is slow and the productivity tends to be lowered. Moreover, the compounding quantity of a vulcanization accelerator becomes like this. Preferably it is 10 weight part or less, More preferably, it is 5 weight part or less. When the blending amount of the vulcanization accelerator exceeds 10 parts by weight, rubber scorch occurs and the physical properties tend to decrease.

  The rubber composition of the present invention contains the filler having two or more protrusions and porous natural glass, and preferably further contains a non-metallic fiber, so that the scratching effect and the drainage effect can be obtained on an icy and snowy road surface. The coefficient of friction is improved, and it is particularly preferably used for a tread rubber of a pneumatic tire.

  As a method for forming the tread, an extrusion process using a normal calendar roll can be used. As described in JP 2001-39104 A, a rubber composition in which fibers are dispersed by a calendar roll is rolled and processed. It is preferable to orient the nonmetallic fibers in the tread thickness direction by a method such as folding the obtained rubber sheet.

  The pneumatic tire of the present invention is produced by a usual method using the rubber composition of the present invention. That is, if necessary, the rubber composition of the present invention blended with the additive is extruded in accordance with the shape of each member of the tire at an unvulcanized stage, and molded by a normal method on a tire molding machine. By doing so, an unvulcanized tire is formed. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a studless tire.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not restrict | limited only to these.

The raw materials used in the examples and comparative examples are summarized below.
Natural rubber: RSS # 3 manufactured by Tech Bee Hang
Polybutadiene rubber: UBEPOL-BR150B manufactured by Ube Industries, Ltd.
Carbon black: Showa Black N220 manufactured by Showa Cabot Corporation
Silica: Ultrazil VN3 manufactured by Degussa
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Anti-aging agent: NOCRACK 6C (N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Wax: Sunnock wax oil manufactured by Ouchi Shinsei Chemical Industry Co., Ltd .: Dyna Process Oil PS323 manufactured by Idemitsu Kosan Co., Ltd.
Stearic acid: Zinc stearate manufactured by Nippon Oil & Fats Co., Ltd .: Zinc Hana No. 1 manufactured by Mitsui Metal Mining Co., Ltd. Glass fiber: Micro chopped strand manufactured by Nippon Sheet Glass Co., Ltd. (average fiber diameter: 11 μm, cut length (Average fiber length): 3 mm)
Zinc oxide whisker: Panatetra WZ-0501 manufactured by Matsushita Amtech Co., Ltd. (number of protrusions: 4, needle-like short fiber length: 2 to 50 μm, needle-like short fiber diameter (average value): 0.2 to 3.0 μm )
Porous natural glass: Hemis Permis LHM-90 (Shirasu, average particle size: 100 μm, average pore size: 5 μm)
Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Examples 1-7 and Comparative Examples 1-9
The ingredients except for sulfur and vulcanization accelerator shown in Tables 1 and 2 are kneaded for 3 to 5 minutes using a closed banbury mixer with a capacity of 1.7 liters. The rubber was discharged and used as a base kneaded rubber. A rubber composition was obtained by kneading the base kneaded rubber with sulfur and a vulcanization accelerator with an open roll and vulcanizing.

  The obtained rubber composition was extruded into a tread shape with a calender roll by a commonly used method to form a tread, and a 195 / 65R15 size tire was produced. The following test was implemented about the obtained tire. The results are shown in Tables 1 and 2.

(Friction performance on ice)
The tire was mounted on a 2000 cc domestic FR vehicle, and the braking stop distance on the ice plate from 30 km / hour was determined. The braking stop distance of Comparative Example 1 is shown as an index with the value being 100. The higher the index, the better the friction performance on ice.

(Abrasion resistance)
The tires were mounted on a 2000 cc domestic FR vehicle and the amount of wear after running 30000 km was measured. The value of the amount of wear in Comparative Example 1 is taken as 100 and is shown as an index. The higher the index, the better the wear resistance.

  In Examples 1 to 3 in which two kinds of Panatetra and porous natural glass were blended in appropriate amounts, and in Examples 4 to 7 in which three kinds of Panatetra, porous natural glass and glass fiber were blended in appropriate quantities, the wear resistance was greatly reduced. The friction performance on ice was able to be improved without causing it. In particular, when (2X + Y + 2Z) was 30 or less, both frictional properties on ice and wear resistance could be achieved.

Claims (4)

A tire rubber composition containing 0.5 to 30 parts by weight of a filler having two or more protrusions and 0.5 to 20 parts by weight of porous natural glass with respect to 100 parts by weight of a diene rubber. Furthermore, it contains 0.5 to 20 parts by weight of nonmetallic fibers having an average fiber diameter of 1 to 100 μm and an average fiber length of 0.1 to 5 mm with respect to 100 parts by weight of the diene rubber. The rubber composition for tires as described. When the compounding amounts of the non-metallic fiber, the filler having two or more protrusions and the porous natural glass are X, Y and Z, respectively, the formula:
2X + Y + 2Z ≦ 30
The rubber composition for tires according to claim 2 satisfying the above. A pneumatic tire comprising the rubber composition for tires according to claim 1, 2 or 3.