JPH1180423A - Rubber composition for tire, and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber compsn. for a tire which possesses excellent performance on ice, abrasion resistance, and standing stability and excellent balance among these properties. SOLUTION: This rubber compsn. for a tire comprises a rubber component comprises: at least one rubber selected from natural rubber and diene synthetic rubber; an azodicarbonamide; zinc benzenesulfinate; and urea. Preferred are an embodiment wherein the amt. of zinc benzenesulfinate compounded and the amt. of urea compounded are each 10 to 200 wt.% based on 100 wt.% azodicarbonamide, an embodiment wherein the amt. of zinc benzenesulfinate compounded is 1 to 100 wt.% based on 100 wt.% azodicarbonamide with the amt. of urea compounded being 10 to 130 wt.% based on 100 wt.% azodicarbonamide, an embodiment wherein the average foam diameter is 25 to 140 μm, and an embodiment wherein the average expansion ratio is 5 to 50%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for a tire and a tire, and more particularly, to a rubber composition for a tire excellent in performance on ice and abrasion resistance and having a good balance between the two. The present invention relates to a tire using a rubber composition.

[0002]

2. Description of the Related Art Since spike tires have been regulated, researches on treads of tires have been actively conducted in order to improve braking / driving performance (on-ice performance) of tires on icy and snowy road surfaces. On the icy and snowy road surface, a water film is easily generated due to frictional heat or the like between the icy and snowy road surface and the tire, and the water film causes a reduction in the coefficient of friction between the tire and the icy and snowy road surface. For this reason, the ability of the tire tread to remove the water film and the edge effect greatly affect the performance on ice. Therefore, in order to improve the performance on ice of the tire, it is necessary to improve the water film removing ability and the edge effect of the tread.

Therefore, a large number of micro drain grooves (both in depth and width of about 100 μm) are provided on the surface of the tire, the water film is eliminated by the micro drain grooves, and the friction of the tire on the ice and snow road surface is reduced. It has been proposed to increase the coefficient. However, in this case, although the performance on ice in the early stage of use of the tire can be improved, there is a problem that the performance on ice is gradually reduced as the tire is worn.

It has been proposed to use foam rubber for the tread in order to prevent the performance on ice from deteriorating even when the tire is worn. Here, dinitrosopentamethylenetetramine (DPT) as a blowing agent
And urea as a foaming aid. But,
In this case, the foaming rate of the foamed rubber changes greatly depending on the elapsed time from the preparation of the kneaded material of the rubber composition to the vulcanization of the rubber composition, and there is a problem in storage stability.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, an object of the present invention is to provide a rubber composition for a tire and a tire excellent in performance on ice, abrasion resistance and storage stability, and having a good balance between them.

[0006]

Means for Solving the Problems As a result of intensive studies by the inventors of the present invention, the following findings have been obtained. That is, when azodicarbonamide (ADCA) as a foaming agent and urea as a foaming aid are used in combination, the change in the foaming rate of the foamed rubber due to the elapsed time from the production of the kneaded material of the rubber composition to the vulcanization. However, the foaming rate is low, and the average foaming rate of the obtained vulcanized rubber cannot be increased to a certain degree or more. Therefore, when azodicarbonamide, zinc benzenesulfinate and urea are used in combination, the zinc benzenesulfinate coordinates to the azodicarbonamide to form a chelate. Can be increased. In addition, it is a finding that a rubber composition for a tire and a tire that are particularly suitable for use on ice, are excellent in the above-mentioned performance on ice, abrasion resistance and storage stability, and have a good balance between them can be obtained.

[0007] The present invention is based on the above findings by the inventors of the present invention, and the means for solving the above problems are as follows. That is, <1> a rubber composition for a tire, comprising at least one of a rubber component selected from a natural rubber and a diene-based synthetic rubber, azodicarbonamide, zinc benzenesulfinate, and urea. <2> The total amount of zinc benzenesulfinate and urea is 1 to 100% by weight of azodicarbonamide.
The rubber composition for a tire according to <1>, which is 0 to 200% by weight. <3> The blending amount of zinc benzenesulfinate is 1 to 100% by weight based on 100% by weight of azodicarbonamide.
And the compounding amount of urea is azodicarbonamide 100
The rubber composition for a tire according to <1> or <2>, which is 10 to 130% by weight with respect to% by weight. <4> The above <1 having an average foam diameter of 25 to 140 μm.
> The rubber composition for a tire according to any one of <3>. <5> The rubber composition for a tire according to any one of <1> to <4>, wherein the average foaming ratio is 5 to 50%.

<6> a pair of bead portions, a carcass connected to the bead portions in a toroidal shape, a belt and a tread for clinching a crown portion of the carcass,
A tire characterized in that the tread comprises the tire rubber composition according to any one of <1> to <5>. <7> In the tread, 10 m from the surface of the tread.
The tire according to <6>, wherein the volume% or more is occupied by the rubber composition for a tire according to any one of <1> to <5>.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

(Rubber composition for tire) The rubber composition for tire of the present invention comprises a rubber component comprising at least one rubber component selected from natural rubber and diene-based synthetic rubber, azodicarbonamide, zinc benzenesulfinate and urea. It contains at least, and further contains other components appropriately selected as necessary.

[0010] The rubber component may contain only natural rubber, may contain only diene-based synthetic rubber, or may contain both. The diene-based synthetic rubber is not particularly limited and can be appropriately selected from known rubbers according to the purpose.
Butadiene copolymer (SBR), polyisoprene (I
R), polybutadiene (BR) and the like. Among these diene-based synthetic rubbers, cis-1,4-polybutadiene is preferred, and those having a cis content of 90% or more are particularly preferred in that they have a low glass transition temperature and a large effect on ice.

When a tire or the like is produced using the rubber composition for a tire of the present invention, the rubber component preferably has a glass transition temperature of -60 ° C. or less. The use of a rubber component having such a glass transition temperature is advantageous in that the tire or the like maintains sufficient rubber elasticity even in a low temperature range and exhibits good on-ice performance.

In the present invention, commercially available products of the azodicarbonamide (ADCA), the zinc benzenesulfinate and the urea can be used.

In the rubber composition for a tire, the amount of the azodicarbonamide may be 100
1.0 to 10.0% by weight with respect to% by weight is preferable,
1.5 to 6.0% by weight is more preferred. Further, in the present invention, the amount of the azodicarbonamide in the rubber composition for a tire is defined as a lower limit or an upper limit of any of the numerical ranges or any of the values in Examples described later as a lower limit. A numerical range having an upper limit of one of the lower limit or upper limit of the numerical range or one of the values in the examples described later is also preferable.

In the tire rubber composition, the amount of the azodicarbonamide is 100% by weight of the rubber component.
On the other hand, if it is less than 1.0% by weight, the foaming rate is too low, and μ on ice may be reduced.
If the ratio exceeds, the foaming ratio may be too high and the wear resistance may decrease.

The amount of the zinc benzenesulfinate and urea in the rubber composition for a tire is 10 to 20 with respect to 100% by weight of the azodicarbonamide.
0% by weight is preferable, and 45 to 120% by weight is more preferable. Further, in the present invention, the amount of the zinc benzenesulfinate and the urea in the rubber composition for a tire may be any one of a lower limit or an upper limit of the numerical value range or any value in Examples described later. It is also preferable that the lower limit is set as the lower limit or upper limit of any of the above numerical ranges or the upper limit is set at any value in the examples described later.

If the amount of the zinc benzenesulfinate and the urea in the rubber composition for a tire is less than 10% by weight based on 100% by weight of the azodicarbonamide, the foaming reaction does not proceed sufficiently. The value of μ on ice may decrease, and if it exceeds 200% by weight, the foaming ratio may be too high and the wear resistance may decrease.

The amount of the zinc benzenesulfinate in the rubber composition for a tire is preferably 1 to 100% by weight, more preferably 4 to 85% by weight, based on 100% by weight of the azodicarbonamide. Further, in the present invention, the amount of the zinc benzenesulfinate in the rubber composition for a tire is defined as a lower limit or an upper limit of any of the numerical ranges or any of the values in the examples described below, A numerical range in which the lower limit or the upper limit of any of the above numerical ranges or the upper limit of any of the values in the examples described later is also preferable.

If the amount of the zinc benzenesulfinate in the rubber composition for a tire is less than 1% by weight with respect to 100% by weight of the azodicarbonamide, the foaming reaction does not sufficiently proceed and the μ on ice is reduced. If the content exceeds 100% by weight, the foaming ratio may be too high and the wear resistance may be reduced.

The amount of the urea in the rubber composition for a tire is preferably 10 to 130% by weight, and more preferably 30 to 11% by weight based on 100% by weight of the azodicarbonamide.
0% by weight is more preferred. Further, in the present invention, the amount of the urea in the rubber composition for the tire is a lower limit or an upper limit of any one of the numerical ranges or any one of the values in the examples described below as a lower limit. A numerical range having an upper limit of any lower limit or upper limit of the range or any value in the examples described later is also preferable.

When the amount of the urea in the rubber composition for a tire is less than 10% by weight based on 100% by weight of the azodicarbonamide, the foaming reaction does not sufficiently proceed, and μ on ice decreases. 130% by weight
If the ratio exceeds, the foaming ratio may be too high and the wear resistance may decrease.

The other components can be appropriately selected according to the purpose within a range that does not impair the effects of the present invention, and commercially available products can be suitably used. Examples of the other components include reinforcing fillers such as carbon black and silica, vulcanizing agents such as sulfur, vulcanization accelerators such as dibenzothiazyl disulfide, vulcanization aids, N-cyclohexyl-2-benzothiazyl. -Antioxidants such as sulfenamide, N-oxydiethylene-benzothiazyl-sulfenamide, zinc oxide, stearic acid, antiozonants, coloring agents, antistatic agents, dispersants, lubricants, antioxidants, and softeners In addition to additives such as inorganic fillers and the like, various compounding agents and the like usually used in the rubber industry are exemplified.

The rubber composition for a tire is, for example, kneaded, heated and extruded under appropriately selected conditions, and is used as a raw material for producing the tire and the like of the present invention. The vulcanization apparatus, system, conditions, etc. are not particularly limited and may be appropriately selected depending on the type and amount of the rubber component, the purpose, and the like. Generally, the vulcanization temperature is, for example, 100 The curing time is, for example, about 5 to 100 minutes.

The kneading is performed by:
There are no particular limitations on the conditions such as the rotation speed of the rotor, the ram pressure, the kneading temperature, the kneading time, and the kneading apparatus, which can be appropriately selected depending on the purpose. As the kneading device, a commercially available product can be suitably used.

The heating or extrusion is not particularly limited with respect to various conditions such as the heating or extrusion time, the heating or extrusion apparatus, and can be appropriately selected according to the purpose. Commercial products can be suitably used as the heating or extruding device.

By the vulcanization, the rubber composition for a tire is vulcanized into a vulcanized rubber (foamed rubber). In the rubber composition for a tire, gas generated from the foaming agent during vulcanization exists as spherical bubbles. When this vulcanized rubber (foamed rubber) is used for, for example, a tread of a tire, when the vulcanized rubber (foamed rubber) is worn, a concave portion due to the spherical bubbles is exposed on the surface thereof, and the concave portion is formed by water. Functions as an efficient drain. Therefore, tires and the like using the rubber composition for tires of the present invention are excellent in the above-mentioned performance on ice.

The average foaming diameter of the vulcanized rubber obtained by vulcanizing the rubber composition for a tire of the present invention is 25 to 140 μm.
Is preferably 25 to 100 μm, more preferably 30 to 100 μm.
100 μm is particularly preferred. Further, as the average foam diameter, the lower limit or the upper limit of any of the numerical ranges or any of the values in the examples described below as a lower limit, the lower limit or the upper limit of any of the numerical ranges or described below. A numerical range with any value in the examples as an upper limit is also preferable.

When rubbers having the same average foaming ratio are compared with each other, when the average foaming diameter exceeds 140 μm, the performance on ice is inferior because the number of concave portions present on a certain rubber surface is too small, and the average diameter is 25 μm. If it is less than 1, the bubble diameter is too small to obtain an effective drain, and the performance on ice may be inferior.

The average foaming ratio Vs of the vulcanized rubber obtained by vulcanizing the rubber composition for a tire of the present invention is preferably 3 to 50%, more preferably 15 to 35%. Further, in the present invention, as the average foaming rate Vs, a lower limit or an upper limit of any of the numerical ranges or a value of the average foaming rate Vs in Examples described later is a lower limit, and a lower limit of any of the numerical ranges is set. A value or an upper limit value or a numerical range in which the value of the average foaming rate Vs in Examples described later is an upper limit is also preferable.

When the average foaming ratio Vs is less than 3%,
A sufficient water exclusion function cannot be obtained due to the absolute lack of the concave volume due to the air bubbles in the generated water film, and the performance of the vulcanized rubber on ice may not be sufficiently improved. On the other hand, if the average foaming rate Vs exceeds 50%, the performance on ice can be improved, but the amount of bubbles in the vulcanized rubber becomes too large, so that the breaking limit of the vulcanized rubber is large. The width may be reduced, the wear resistance may be reduced, and the balance between on-ice performance and wear resistance may be lost. The average foaming rate Vs can be adjusted by appropriately changing the amounts of the azodicarbonamide, the zinc benzenesulfinate and the urea.

The average foaming ratio Vs is expressed by the following equation: Vs =
(Ρ ₀ / ρ ₁ −1) × 100 (%). Here, ρ ₁ represents the density (g / cm ³ ) of a vulcanized rubber (foamed rubber) obtained by vulcanizing a rubber composition for a tire.
ρ ₀ represents the density (g / cm ³ ) of a solid phase portion in a vulcanized rubber (foamed rubber) obtained by vulcanizing a rubber composition for a tire. The density of the vulcanized rubber (foamed rubber) obtained by vulcanizing the rubber composition for tires and the density of the solid phase portion in the vulcanized rubber (foamed rubber) obtained by vulcanizing the rubber composition for tires are as follows: For example, the weight in ethanol and the weight in air can be measured and calculated from them.

In the present invention, the average foam diameter and the average foam ratio generally have the following relationship.
That is, when the average foaming diameter is within a certain numerical range, that is, 25 to 140 μm of the numerical range, the on-ice performance of the vulcanized rubber obtained by vulcanizing the rubber composition for tires is the average. It depends more on the average foaming rate than on the foaming diameter. On the other hand, when the average foaming rate is constant, the larger the average foaming diameter, the longer the average distance between individual cells that can be a nucleus at the time of destruction, and as a result, one of the cells Even if a break occurs, the break hardly propagates, and the wear resistance is improved. Therefore, depending on the purpose, by appropriately selecting the average foaming diameter in the above numerical range and the average foaming rate in the above numerical range, the performance on ice, excellent abrasion resistance and storage stability, and these Vulcanized rubber (foamed rubber) with a good balance can be obtained.

The rubber composition for a tire of the present invention can be particularly suitably used for a structure that requires suppression of slip on ice. Examples of the structure include a tread of a tire and a retreaded tire. Treads for replacement, solid tires, grounded portions of rubber tire chains used for running on icy and snowy roads, snowmobile crawlers, shoe soles, and the like are particularly preferable. Of these, the rubber composition for a tire of the present invention is particularly preferable when used for a tread of a tire, since the performance on ice, abrasion resistance and storage stability of the tire can be improved in a well-balanced manner.

(Tire) The tire of the present invention has at least a tread, and other configurations are not particularly limited as long as the tread is formed using the rubber composition for a tire of the present invention. Can be appropriately selected according to the purpose.

As shown in FIG. 1, the tire 4 of the present invention has a pair of bead portions 1, a carcass 2 connected to the pair of bead portions 1 in a toroidal shape, and a crown portion of the carcass 2. Has a radial structure in which a belt 3 and a tread 5 to be fastened are sequentially arranged, and the tread 5 includes at least a vulcanized rubber obtained by vulcanizing the rubber composition for a tire of the present invention. Note that the internal structure other than the tread 5 is the same as the structure of a general radial tire, and a description thereof will be omitted.

As shown in FIG. 2, a plurality of blocks 10 are formed in the tread 5 by a plurality of circumferential grooves 8 and a plurality of transverse grooves 9 intersecting the circumferential grooves 8. The block 10 has a sipe 11 extending in the tire width direction (B direction) in order to improve braking performance and traction performance on ice.

The tread 5 is composed of an upper cap portion directly in contact with the road surface and a lower base portion disposed adjacent to the inside of the tire of the cap portion, and has a so-called cap-base structure. ing. The cap portion is a foamed rubber containing a myriad of spherical bubbles, and the base portion is made of a normal rubber that is not foamed. The foamed rubber is a vulcanized rubber obtained by vulcanizing the rubber composition for a tire of the present invention.

In the tire tread 5 of the present invention, the vulcanized rubber obtained by vulcanizing the rubber composition for a tire is as follows:
The proportion occupied by the surface of the tread 5 is preferably 10% by volume or more, more preferably 50 to 100% by volume. When the ratio is less than 10% by volume, the performance on ice may be deteriorated, which is not preferable.

The method for producing the tire 4 is not particularly limited, but can be produced, for example, as follows. That is, first, a tread is produced by using the rubber composition for a tire of the present invention in a cap portion. The tread is stuck on an unvulcanized belt portion previously stuck to the crown portion of the green tire case. Then, vulcanization molding is performed in a predetermined mold under a predetermined temperature and a predetermined pressure. As a result, a tire 4 having a cap portion 6 formed of a vulcanized rubber obtained by vulcanizing the rubber composition for a tire of the present invention on a vulcanized base portion 7 is obtained.

At this time, when the unvulcanized tire is heated in the mold, in the rubber composition for a tire,
Along with the vulcanization reaction, foaming by the foaming agent occurs to generate gas. As a result, the spherical bubbles are present in the cap portion after cooling, and the cap portion is a vulcanized rubber having a high foaming rate.

Next, the operation of the tire 4 will be described.
When the tire 4 is run on an icy and snowy road surface, the recess due to the air bubbles is exposed on the ground contact surface of the cap portion of the tread 5 at an extremely early stage of wear. A water film is formed on the ice and snow road surface due to the contact pressure of the tread 5 with respect to the ice and snow road surface and frictional heat, and the water film is quickly removed by the myriad of concave portions exposed on the contact surface of the cap portion of the tread 5. ,
Removed. In the tire 4, the concave portion functions as a drainage channel for draining water efficiently, and the concave portion improves the water removal performance, and thus is particularly excellent in braking performance on ice. Further, in the tire 4, the concave portion has a scratching effect, so that the μ on the ice in the horizontal direction is improved by the scratching effect, and the handling on the ice is good.

The tire of the present invention can be suitably applied not only to so-called passenger cars but also to heavy-duty vehicles such as trucks and buses.

[0042]

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

(Examples 1 to 13 and Comparative Examples 1 to 9) Table 1
And the rubber composition for tires of the composition shown in Table 2 was prepared.
A tread in a tire was formed using the rubber composition for a tire, and a cap portion of the tread was formed from the rubber composition for a tire of the present invention (70% from the surface of the tread).
% By volume of the rubber composition for a tire of the present invention) tire,
It was manufactured under normal tire manufacturing conditions. This tire is a radial tire for heavy load vehicles, has a tire size of 11R / 22.5, and has a structure as shown in FIG. That is, the pair of bead portions 1 and the pair of bead portions 1
A carcass 2, a belt 3 for clasping a crown portion of the carcass 2, and a tread 5
Have a radial structure in which are sequentially arranged.

As shown in FIG. 2, six blocks 10 are arranged on the tread 5 of the tire 4 in the tire width direction. The size of the block 10 is 6 in the tire circumferential direction.
0 mm, and the dimension in the tire width direction is 35 mm.
The sipe 11 formed in the block 10 has a width of 1 mm and an interval in the tire circumferential direction of about 10 mm.

(Examples 14 to 26 and Comparative Examples 10 to 1)
7) Rubber compositions having the compositions shown in Tables 3 and 4 were prepared.
A tread for a tire was formed using the rubber composition, and a cap portion of the tread was formed from the rubber composition for a tire of the present invention (70% by volume from the surface of the tread was used for the tire of the present invention). Rubber composition) A tire was manufactured under normal tire manufacturing conditions. This tire is a radial tire for passenger cars, and its tire size is 185 /.
70R13, and its structure is as shown in FIG.
That is, a radial structure in which a pair of bead portions 1, a carcass 2 connected in a toroidal shape to the pair of bead portions 1, a belt 3 for clinching a crown portion of the carcass 2, and a tread 5 are sequentially arranged. Having.

As shown in FIG. 3, four blocks 10 are arranged in the tread 5 of the tire 4 in the tire width direction. The size of the block 10 is 3 in the tire circumferential direction.
5 mm, and the dimension in the tire width direction is 30 mm.
The sipe 11 formed in the block 10 has a width of 0.4 mm and an interval in the tire circumferential direction of about 7 mm.

Each of the obtained tires was evaluated for performance on ice, abrasion resistance and storage stability. The results are shown in Tables 1 to 4, respectively.

<Performance on Ice> Examples 1 to 13 and Comparative Example 1
Example 14 was mounted on a 10-ton truck,
After mounting the tires of Nos. 26 to 26 and Comparative Examples 8 to 11 on a 1600cc class passenger car, and running the 10t truck and the passenger car on a general asphalt road for 200 km,
The vehicle was driven on a flat road on ice, the brake was depressed at a speed of 20 km / h to lock the tires, and the distance to stop was measured. In the results of Examples 1 to 13 and Comparative Examples 1 to 7, the reciprocal of the distance was represented by an index with the tire of Comparative Example 1 being 100. In the results of Examples 14 to 26 and Comparative Examples 8 to 11, the reciprocal of the distance was represented by an index with the tire of Comparative Example 8 being 100. The larger the value, the better the performance on ice.

<Wear Resistance> Examples 1 to 13 and Comparative Example 1
Example 14 was mounted on a 10-ton truck,
Each of the tires of Nos. To 26 and Comparative Examples 9 to 12 was mounted on a 1600 cc class passenger car, and the 10-ton truck and the passenger car were run 20,000 km on a general asphalt road, and then the wear amount of the block 10 was measured. In the results of Examples 1 to 13 and Comparative Examples 1 to 7, the distance traveled until worn by 1 mm (i.e., 20,000 (km) / amount of wear (mm)) was expressed as an index with the tire of Comparative Example 1 as 100. . Example 1
In the results of Examples 4 to 26 and Comparative Examples 8 to 11, the distance traveled until the tires were worn by 1 mm (that is, 20,000 (km) / amount of wear (mm)) was expressed as an index, with the tire of Comparative Example 8 being 100. The larger the value, the better the wear resistance.

<Standing Stability> The foaming ratio (INDEX) of a tire manufactured using the above rubber composition for tires left for 360 hours at 30 ° C. and 80% humidity was measured. The results of Examples 1 to 14 and Comparative Examples 1 to 7,
The tire of Comparative Example 1 was indexed as 100. The results of Examples 14 to 26 and Comparative Examples 8 to 11 were indexed with the tire of Comparative Example 8 as 100. The smaller the value, the better the standing stability.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

[Table 4]

In Tables 1 to 4, "butadiene rubber" means cis-1,4-polybutadiene (BR01 manufactured by Nippon Synthetic Rubber Co., Ltd.), and the glass transition temperature of the rubber component is -60 ° C. or lower. It is. "Carbon black"
Is made by Tokai Carbon Co., Ltd., Seast 9 (carbon N1
10), and “antiaging agent” means Nocrack 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd. `` Vulcanization accelerator ''
Means N-cyclohexyl-2-benzothiazyl-sulfenamide. "Blowing agent DPT" means dinitrosopentamethylenetetramine. "Blowing agent
"ADCA" means azodicarbonamide. “Zinc benzenesulfinate” means manufactured by Otsuka Chemical Co., Ltd.

The “foaming rate (%)” is the value of the average foaming rate (%) calculated (measured) according to the above-mentioned formula for five samples sampled at random. “Average foam diameter (μm)” is measured using an image analyzer (LIREX5
000), the foam in the 1 mm × 1 mm photograph of the cross section of the tread was regarded as a circle, the diameter thereof was measured, and the average value was calculated. "30 ° C, 80% humidity, foaming rate after 360 hours"
Is an index of the change in each foaming ratio when the change in the foaming ratio in Comparative Example 1 or Comparative Example 11 is set to 100,
The smaller the value, the more time is allowed from the kneading of the foaming agent to the rubber component to the vulcanization, which is preferable.

From the results in Tables 1 to 4, the tire of the present invention in which a tread was formed using the rubber composition for a tire of the present invention had the above-mentioned performance on ice, abrasion resistance and standing compared to the tire of the comparative example. It is clear that they are excellent in stability and excellent in balance between them.

[0058]

According to the present invention, the above-mentioned conventional problems can be solved. Further, according to the present invention, it is possible to provide a rubber composition for a tire and a tire which are excellent in performance on ice, abrasion resistance and storage stability, and have a good balance among them.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a partial cross section of a tire according to the present invention.

FIG. 2 is a partially schematic explanatory view of a peripheral surface of a tire (for a heavy load vehicle) of the present invention.

FIG. 3 is a partially schematic explanatory view of a peripheral surface of a tire (for a passenger car) of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 A pair of bead parts 2 Carcass 3 Belt 4 Tire 5 Tread 8 Circumferential groove 9 Horizontal groove 10 Block 11 Sipe CL Center line

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 5/21 C08K 5/21 5/23 5/23 5/41 5/41 C08L 7/00 C08L 7/00

Claims (7)

[Claims] 1. A tire rubber composition comprising at least one rubber component selected from natural rubber and diene-based synthetic rubber, azodicarbonamide, zinc benzenesulfinate and urea. 2. The rubber composition for a tire according to claim 1, wherein the total amount of zinc benzenesulfinate and urea is 10 to 200% by weight based on 100% by weight of azodicarbonamide. 3. The compounding amount of zinc benzenesulfinate is:
1 to 100 based on 100% by weight of azodicarbonamide
The rubber composition for a tire according to claim 1 or 2, wherein the amount of urea is 10 to 130% by weight based on 100% by weight of azodicarbonamide. 4. The rubber composition for a tire according to claim 1, wherein the average foam diameter is 25 to 140 μm. 5. The method according to claim 1, wherein the average foaming ratio is 5 to 50%.
5. The rubber composition for a tire according to any one of items 1 to 4. 6. A vehicle comprising: a pair of bead portions; a carcass connected to the bead portion in a toroidal shape; a belt for tightening a crown portion of the carcass; 5. A tire, comprising the rubber composition for a tire according to any one of the above items 5. 7. The tire according to claim 6, wherein the rubber composition for a tire according to any one of claims 1 to 5 accounts for at least 10% by volume of the tread from the surface of the tread.