JP2008163212A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition capable of improving the abrasion resistance of a tire without worsening the rolling resistance of the tire. <P>SOLUTION: The rubber composition is obtained by formulating a rubber component containing a diene-based rubber with carbon black in which a pore volume Y (ml/100 g) measured by mercury porosimetry, dibutyl phthalate oil absorption DBP (ml/100 g) and a nitrogen adsorption specific surface area N<SB>2</SB>SA (m<SP>2</SP>/g) satisfy formula (I): Y>0.22×DBP-0.21×N<SB>2</SB>SA+63. The tire is obtained by applying the rubber composition to a tire member such as tread. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rubber composition and a tire using the rubber composition, and particularly to a rubber composition capable of improving wear resistance without deteriorating rolling resistance of the tire when applied to a tire tread. It is about.

In general, since a tire tread requires high wear resistance, carbon black is blended as a highly reinforcing filler in a rubber composition for a tread. In addition, various properties of the tire can be adjusted by selecting various physical properties of the carbon black to be used. For example, by applying carbon black having a large nitrogen adsorption specific surface area N ₂ SA, the carbon black and the rubber component The contact area with can be increased. Further, by applying carbon black having a high dibutyl phthalate oil absorption, the interaction between the carbon black and the rubber component can be increased, and as a result, the wear resistance of the rubber composition can be improved. And the abrasion resistance of a rubber composition can be improved also by increasing the compounding quantity of carbon black.

On the other hand, under the social demand for energy and resource saving, it has become necessary to reduce the rolling resistance of tires in order to save fuel consumption of automobiles. On the other hand, carbon black having a small nitrogen adsorption specific surface area N ₂ SA is applied as a reinforcing filler of the rubber composition applied to the tread to reduce the contact area between the carbon black and the rubber component, thereby dibutyl phthalate. By applying carbon black having a small oil absorption amount and reducing the interaction between the carbon black and the rubber component, the rolling resistance of the tire can be reduced. Also, the rolling resistance of the tire can be reduced by reducing the blending amount of carbon black.

  However, when controlling the characteristics of the tire by controlling the properties of the carbon black used in the rubber composition for treads, as described above, the improvement in wear resistance and the reduction in rolling resistance are in a trade-off relationship, and rolling resistance It is difficult to improve the wear resistance without deteriorating.

On the other hand, Patent Document 1 is excellent in wear resistance and low heat build-up by applying carbon black having a specific range of nitrogen adsorption specific surface area N ₂ SA, dibutyl phthalate oil absorption and aggregate void volume. It is disclosed that a rubber composition can be obtained.
Further, Patent Document 2 applies a carbon black in which the pore volume by the mercury porosimeter method and the volume of the pores occupying the maximum peak of the pore distribution in the mercury porosimeter method are in a specific range. It discloses that a rubber composition with improved exothermic properties can be obtained.
Furthermore, Patent Document 3 discloses wear resistance by blending carbon black satisfying a certain relationship between pore volume (cc / g) calculated from a nitrogen adsorption isotherm and cetyltrimethylammonium bromide (CTAB) adsorption specific surface area. It is disclosed that a rubber composition having excellent rolling resistance and low rolling resistance can be obtained.
However, even with the above technique, it is difficult to achieve both high wear resistance and rolling resistance, and there is still room for improvement.

JP-A-2-129242 JP-A-3-149236 JP 2006-160873 A

  Accordingly, an object of the present invention is to provide a rubber composition capable of solving the above-described problems of the prior art and improving the wear resistance of the tire without deteriorating the rolling resistance of the tire. Another object of the present invention is to provide a pneumatic tire having low rolling resistance and excellent wear resistance using such a rubber composition.

As a result of intensive studies to achieve the above object, the present inventor has found that a rubber composition containing a diene rubber has a pore volume measured by mercury porosimetry, a dibutyl phthalate oil absorption DBP, and a nitrogen adsorption specific surface area N ₂ SA. It was found that by adding carbon black satisfying a specific relational expression, the wear resistance of the tire can be improved without deteriorating the rolling resistance of the tire, and the present invention has been completed.
That is, according to the present invention, the pore volume Y (ml / 100 g), dibutyl phthalate oil absorption DBP (ml / 100 g) and nitrogen adsorption specific surface area N ₂ measured by mercury porosimetry for rubber components containing diene rubber. SA (m ² / g) is the following formula (I):
Y> 0.22 × DBP−0.21 × N ₂ SA + 63... (I)
A rubber composition obtained by blending carbon black satisfying the above relationship, and a tire applied to any of the tire members, particularly a tire applied to a tread.

  According to the present invention, by adding carbon black satisfying the above formula (I) to the rubber composition as a reinforcing filler, it is possible to improve the tire wear resistance without deteriorating the rolling resistance of the tire. A rubber composition can be provided. In addition, a pneumatic tire having low rolling resistance and excellent wear resistance using such a rubber composition can be provided.

  The present invention is described in detail below. In general, reducing the particle size of carbon black increases the volume between carbon black particles and increases the contact area between the carbon black and the rubber component. The abrasion resistance of the rubber composition can be improved. However, since the fine particle size carbon black has a large contact area with the rubber component, when a rubber composition containing the fine particle size carbon black is applied to a tire, the rolling resistance of the tire increases. Therefore, if carbon black having a fine particle size is used, the wear resistance and rolling resistance cannot be improved at the same time. Furthermore, carbon black having a fine particle size generally has poor dispersibility in rubber, and if the dispersion state of carbon black in rubber is poor, the wear resistance of the rubber composition is lowered. If the dispersion state is to be improved, the processability and productivity of the rubber composition will be remarkably deteriorated.

On the other hand, in the present invention, the carbon black having the same particle diameter is greatly improved in the dispersibility of carbon black in rubber by greatly increasing the pore volume measured by mercury porosimetry. Achieving both wear and low rolling resistance.
In the rubber composition of the present invention, the pore volume Y, the dibutyl phthalate oil absorption DBP (hereinafter referred to as DBP), and the nitrogen adsorption specific surface area N ₂ SA (measured by mercury porosimetry) with respect to a rubber component containing a diene rubber. Hereinafter, carbon black satisfying the relationship of the above formula (I) is blended with N ₂ SA.
The blending amount of the carbon black is preferably 20 to 200 parts by mass, more preferably 40 to 100 parts by mass with respect to 100 parts by mass of the rubber component.
When the blending amount of the carbon black is 20 parts by mass or more with respect to 100 parts by mass of the rubber component, the wear resistance of the rubber composition is improved, and when it is 200 parts by mass or less, the low exothermic property of the rubber composition is low. This is preferable because the rolling resistance of a tire using the rubber composition is reduced and the fuel efficiency is improved.

The carbon black according to the present invention preferably has a DBP of 120 to 220 ml / 100 g, and more preferably 130 to 180 ml / 100 g. When carbon black having a DBP of 120 ml / 100 g or more is used, the wear resistance of the rubber composition is greatly improved. On the other hand, a DBP of 220 ml / 100 g or less is preferable because the processability of the rubber composition is improved.
Also, N ₂ SA is preferably from 60~180m ² / g, more preferably from 80~160m ² / g. When carbon black having N ₂ SA of 60 m ² / g or more is used, the wear resistance of the rubber composition is greatly improved. On the other hand, if N ₂ SA is 180 m ² / g or less, the rolling resistance of the tire is reduced. It is preferable without deteriorating. Further, since the dispersibility of carbon black in the rubber component is not lowered, the wear resistance can be more preferably improved.

  The carbon black having various physical properties is, for example, a feedstock introduction amount [kg / h], a feedstock preheating temperature [° C.], a fuel introduction amount [kg / h], a total introduction air amount [kg / h] in a carbon black production furnace. h], air preheating temperature [° C.], reaction time [sec], average reaction temperature [° C.] and the like.

  The rubber component of the rubber composition of the present invention needs to contain at least a diene rubber, and preferably contains 10% by mass or more of the diene rubber. Here, examples of the diene rubber include natural rubber (NR) and diene synthetic rubber such as polyisoprene rubber (IR), polybutadiene rubber (BR), and styrene-butadiene copolymer rubber (SBR). These rubber components may be used alone or in a blend of two or more.

  In the rubber composition of the present invention, in addition to the above carbon black, compounding agents usually used in the rubber industry such as a vulcanizing agent, a vulcanization accelerator, zinc oxide, stearic acid, an anti-aging agent, etc. It can be appropriately selected and blended within a range that does not impair the purpose. As these compounding agents, commercially available products can be suitably used. Further, the rubber composition can be produced by blending carbon black and various appropriately selected compounding ingredients with a rubber component, kneading, heating, extruding, and the like.

  The pneumatic tire of the present invention is characterized in that the rubber composition is applied to any of tire members. Here, in the tire of the present invention, it is particularly preferable to use the rubber composition for a tread. The tire using the rubber composition for a tread has excellent wear resistance, low rolling resistance, and low fuel consumption. Excellent. In addition, as gas with which the tire of the present invention is filled, normal or air with a changed oxygen partial pressure, or an inert gas such as nitrogen is exemplified.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

Examples 1-4 and Comparative Examples 1-3
Seven types of carbon black were produced under the conditions shown in Table 1, using petroleum heavy oil as the raw material oil and A heavy oil as the fuel. These seven types of carbon blacks were kneaded with a Banbury mixer to prepare rubber compositions having the formulation shown in Table 2. In addition, DBP, N ₂ SA, and pore volume Y of carbon black used in each rubber composition were measured by the following methods. The results are shown in Table 1.

(1) DBP
Based on the ISO 4656-1 method, the oil absorption (ml / 100 g) of dibutyl phthalate (DBP) per 100 g of each carbon black was measured.
(2) N ₂ SA
Based on the ISO 4652-1 method, the specific surface area (m ² / g) per unit mass of each carbon black was measured.
(3) Pore volume Y
Using a mercury porosimeter manufactured by Quantachrome, mercury was injected while changing the pressure from 20 psi to 30,000 psi, and the pore volume of carbon black was measured. When mercury is injected from low pressure, the entire surface of carbon black is covered with mercury. During this time, mercury is injected linearly with pressure. When a certain pressure is exceeded, mercury begins to be injected into the pores of carbon black, and the mercury injection curve loses linearity and rises rapidly. The amount of press-in per 100 g of carbon black from this point until the press-in curve was saturated was defined as Y (ml / 100 g).

Next, using the obtained rubber composition as a tread, seven types of tires for trucks of size 11R22.5 were manufactured, and the wear resistance and rolling resistance of the tires were evaluated by the following methods. The results are shown in Table 1.
(4) Tire Abrasion Resistance When the truck tire is mounted on a vehicle and measured for a reduction in the groove of the tire when traveling 40,000 km, the reciprocal of the reduction in the groove of the tire in Comparative Example 1 is defined as 100. It was displayed as an index. It shows that it is excellent in abrasion resistance, so that an index value is large.
Abrasion resistance index = (groove reduction of tire of comparative example 1 / groove reduction of target tire) × 100
(5) Rolling resistance of tire The above-mentioned truck tire was freely rotated on a drum, and the rolling resistance was measured. The obtained rolling resistance value is expressed by the following formula:
Rolling resistance index = (Rolling resistance of target tire / Rolling resistance of tire of Comparative Example 1) × 100
According to the index. The smaller the index value, the smaller the rolling resistance and the better.

The carbon black used in Example 1 is substantially equivalent to the carbon black used in Comparative Example 1 and N ₂ SA. However, since the relational expression of the above formula (I) is satisfied and DBP is slightly high, Example 1 As compared with the tire of Comparative Example 1, this tire significantly improved the wear resistance without deteriorating the rolling resistance of the tire.

Further, the carbon black used in Example 2 is substantially equivalent to the carbon black used in Comparative Example 2 but N ₂ SA, but satisfies the relational expression of the above formula (I) and has a DBP of 120 (ml / 100 g). ), The tire of Example 2 significantly improved the wear resistance and the rolling resistance of the tire compared to the tire of Comparative Example 2.

The carbon black used in Example 3 satisfied the relational expression of the above formula (I), and N ₂ SA was larger than the carbon black used in Comparative Example 3, so that the wear resistance was greatly improved.
The carbon black used in Example 4 satisfies the relational expression of the above formula (I). However, since N ₂ SA is less than 60 m ² / g, the wear resistance is inferior to that of Example 3. However, the wear resistance of the carbon black used in Example 4 was improved compared to the carbon black used in Comparative Example 3 in which N ₂ SA was equivalent and did not satisfy the relational expression of the above formula (I).

  The rubber composition of the present invention is used for various pneumatic tires for passenger cars, small trucks, light passenger cars, light trucks and large vehicles (for trucks, buses, construction vehicles, etc.), particularly pneumatic radial tires. It is suitably used as a tread member or a side wall member.

Claims (7)

For rubber components including diene rubber, pore volume Y (ml / 100 g), dibutyl phthalate oil absorption DBP (ml / 100 g) and nitrogen adsorption specific surface area N ₂ SA (m ² / g) measured by mercury porosimetry. ) And the following formula (I):
Y> 0.22 × DBP−0.21 × N ₂ SA + 63... (I)
A rubber composition comprising carbon black satisfying the above relationship.   The rubber composition according to claim 1, wherein the carbon black has a dibutyl phthalate oil absorption DBP of 120 to 220 ml / 100 g. The rubber composition according to claim 1 or 2, wherein the carbon black has a nitrogen adsorption specific surface area N ₂ SA of 60 to 180 m ² / g.   The rubber composition according to any one of claims 1 to 3, wherein a blending amount of the carbon black is 20 to 200 parts by mass with respect to 100 parts by mass of the rubber component.   The rubber composition according to any one of claims 1 to 4, wherein the diene rubber is a rubber selected from the group consisting of natural rubber, polyisoprene rubber, polybutadiene rubber, and styrene-butadiene copolymer rubber. .   The tire which applied the rubber composition in any one of Claims 1-5 to any of the tire members.   The tire according to claim 6, wherein the tire member is a tread.