JP2009263545A - Rubber composition for tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for tire which has both of wear resistant and low heat generation. <P>SOLUTION: The rubber composition is prepared by blending 30-50 pts.wt. carbon black to 100 pts.wt. diene based rubber containing 20-70 wt.% butadiene rubber containing syndiotactic-1,2-polybutadiene, wherein the ratio N<SB>2</SB>SA/IA of the nitrogen adsorption specific surface area N<SB>2</SB>SA [m<SP>2</SP>/g] of carbon black to iodine adsorption IA [mg/g] is 1.10-1.30, DBP absorption is 50-70 cm<SP>3</SP>/100g and CTAB adsorption specific surface area is 80-100 m<SP>2</SP>/g. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubber composition for tires, and more particularly, to a rubber composition for tires suitable as a sidewall for making both wear resistance and heat generation compatible.

  A sidewall of a pneumatic tire is required to have excellent wear resistance because it easily contacts with curbs. At the same time, the sidewall is required to have a low exothermic property in order to generate a large amount of deformation during traveling and easily generate heat, and when the amount of generated heat is large, the rolling resistance increases and the fuel consumption rate increases.

  In general, it is known to increase the amount of carbon black in order to improve the wear resistance. However, when the amount of carbon black is increased, exothermic properties are deteriorated and extrusion processability is deteriorated due to an increase in viscosity. On the other hand, in order to make the rubber composition have low exothermic properties, it is known to add silica, but the wear resistance and extrusion processability are deteriorated. Thus, wear resistance, exothermic property and extrusion processability are contradictory properties, and it has been difficult to achieve all of these physical properties.

Patent Document 1 uses a butadiene rubber containing syndiotactic-1,2-polybutadiene as a new rubber composition for sidewalls, and limits the CTAB adsorption specific surface area of carbon black, thereby improving wear resistance (trauma resistance). It is proposed to improve the property. However, although this method improves the wear resistance, there has been a problem that the exothermic property of the rubber composition has not been improved.
JP 2005-133017 A

  An object of the present invention is to provide a rubber composition for tires, particularly a rubber composition for sidewalls, which makes it possible to achieve both wear resistance and heat generation without deteriorating extrusion processability.

The rubber composition for a tire according to the present invention that achieves the above object comprises 30 to 50% carbon black with respect to 100 parts by weight of a diene rubber containing 20 to 70% by weight of a butadiene rubber containing syndiotactic-1,2-polybutadiene. The ratio N ₂ SA / IA of the nitrogen adsorption specific surface area N ₂ SA [m ² / g] and iodine adsorption amount IA [mg / g] of the carbon black is 1.10 to 1.30, DBP absorption 50~70cm ³ / 100g, CTAB adsorption specific surface area characterized in that it is a 80~100m ² / g.

  This tire rubber composition is suitable for constituting a sidewall portion of a pneumatic tire.

The tire rubber composition of the present invention improves the wear resistance of the rubber composition by blending 20 to 70% by weight of butadiene rubber containing syndiotactic-1,2-polybutadiene in the diene rubber. for the diene rubber 100 parts by weight, the ratio _N 2 SA / IA of iodine adsorption IA intoxicated with the nitrogen adsorption specific surface area _N 2 SA _1.10~1.30, DBP absorption amount of 50 to 70 cm ³ / 100 g, 30 to 50 parts by weight of carbon black having colloidal characteristics of CTAB adsorption specific surface area of 80 to 100 m ² / g was added so that extrudability and extrudability of the rubber composition were not deteriorated. It is possible to achieve both wear resistance and heat generation without deteriorating the performance.

  In the rubber composition for tires of the present invention, examples of the diene rubber include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, and butyl rubber, which are usually used in tire rubber compositions. These diene rubbers can be used alone or as any blend. The butadiene rubber blended as the diene rubber excludes butadiene rubber containing syndiotactic-1,2-polybutadiene.

  The diene rubber must contain 20 to 70% by weight of butadiene rubber including syndiotactic-1,2-polybutadiene. Thereby, while improving the abrasion resistance of a rubber composition, the effect of improving the extrusion property at the time of a shaping | molding process is acquired.

  The blending ratio of the butadiene rubber containing syndiotactic-1,2-polybutadiene in the diene rubber is 20 to 70% by weight, more preferably 30 to 65% by weight. If the butadiene rubber containing syndiotactic-1,2-polybutadiene is less than 20% by weight, the effect of improving wear resistance and extrusion processability cannot be obtained. When the butadiene rubber containing syndiotactic-1,2-polybutadiene exceeds 70% by weight, the exothermic property of the rubber composition is deteriorated.

  Syndiotactic-1,2-polybutadiene is a resin with high crystallinity and is finely dispersed in butadiene rubber. The content of syndiotactic-1,2-polybutadiene in the butadiene rubber is preferably 1 to 20% by weight, more preferably 3 to 15% by weight. If it is less than 1% by weight, the effect of improving the wear resistance and extrusion processability cannot be obtained, and if it exceeds 20% by weight, the exothermic property of the rubber composition is deteriorated. As the butadiene rubber containing the above-mentioned syndiotactic-1,2-polybutadiene, a commercially available rubber can be used, and examples thereof include UBEPOL-VCR412, VCR617, VCR450, VCR800 and the like manufactured by Ube Industries, Ltd. .

  In the present invention, by adding a butadiene rubber containing syndiotactic-1,2-polybutadiene to the rubber composition, the wear resistance and the heat resistance are improved, but the exothermic property is deteriorated. By selecting the colloidal characteristics of the rubber composition as follows, the exothermic deterioration of the rubber composition is suppressed, and both wear resistance and exothermicity can be achieved.

The colloidal characteristic of the carbon black used in the present invention is such that the ratio N ₂ SA / IA of the nitrogen adsorption specific surface area N ₂ SA [m ² / g] and the iodine adsorption amount IA [mg / g] is 1.10 to 1 .30, preferably 1.12 to 1.27. When the ratio N ₂ SA / IA is less than 1.10, the exothermic property of the rubber composition is deteriorated. When the ratio N ₂ SA / IA exceeds 1.30, the extrusion processability of the rubber composition is deteriorated. The nitrogen adsorption specific surface area N ₂ SA is measured according to JIS K6217-2, and the iodine adsorption amount IA is measured according to JIS K6217-1.

DBP absorption of carbon black is 50 to 70 cm ^3/100 g, may preferably in 55~70cm ³ / 100g. DBP absorption is insufficient wear resistance is less than 50 cm ^3/100 g. When more than 70cm ^3/100 g, the extrusion processability of the rubber composition is deteriorated. The DBP absorption amount shall be measured according to JIS K6217-4 oil absorption amount A method.

The CTAB adsorption specific surface area is 80 to 100 m ² / g, and preferably 80 to 95 m ² / g. When the CTAB adsorption specific surface area is less than 80 m ² / g, the wear resistance is insufficient. When it exceeds 100 m ² / g, the exothermic property of the rubber composition is deteriorated. The CTAB adsorption specific surface area is measured according to JIS K6217-3.

  The carbon black having the colloidal characteristics may be selected from commercially available ones, or may be used by using a known carbon black production apparatus, introduction position, introduction amount, introduction pressure and temperature, introduction of raw oil. The generation conditions such as the total air amount and the cooling water introduction position for stopping the reaction may be prepared and appropriately manufactured.

  The compounding quantity of carbon black is 30-50 weight part with respect to 100 weight part of diene rubber, Preferably it is good to set it as 35-45 weight part. When carbon black is less than 30 parts by weight, the wear resistance is insufficient. If the amount of carbon black exceeds 50 parts by weight, the heat build-up will deteriorate.

  Various additives commonly used in rubber compositions such as vulcanization or cross-linking agents, anti-aging agents, and plasticizers can be blended with the rubber composition for tires. And kneaded into a rubber composition which can be used for vulcanization or crosslinking. The blending amounts of these additives may be conventional conventional blending amounts as long as the object of the present invention is not adversely affected.

  The rubber composition for tires can be produced by mixing each of the above components using a known rubber kneading machine such as a Banbury mixer, a kneader, or a roll.

  The rubber composition for tires of the present invention can be applied to casing compounds such as tread parts, sidewall parts, bead parts, etc. of pneumatic tires, various coated rubbers, etc., and is particularly suitable as a rubber composition for sidewalls. is there. Moreover, the pneumatic tire having a sidewall portion made of the rubber composition of the present invention suppresses heat generation during running and is excellent in wear resistance.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

  Using seven types of carbon black (CB-1 to CB-7) shown in Table 1, 14 types of rubber compositions (Examples 1 to 5, Standard Example, Comparative Example 1) having the formulations shown in Tables 2 and 3 In preparing ~ 8), components excluding sulfur and vulcanization accelerator were weighed, kneaded for 3 to 5 minutes in a 1.8 L closed mixer, and the master batch was discharged at a temperature of 140 to 160 ° C. This master batch was subjected to an 8-inch open roll, sulfur and a vulcanization accelerator were added at a temperature of 50 to 80 ° C., and kneaded to obtain each rubber composition. Part of the obtained 14 kinds of rubber compositions (Examples 1 to 5, Standard Examples and Comparative Examples 1 to 8) were subjected to an extrudability test, and the remaining part was used for abrasion resistance and viscoelasticity tests. Each was vulcanized at 150 ° C. for 30 minutes in a mold having a predetermined shape to prepare a test piece, and the test was performed by the method shown below.

Extrudability Using a single-screw extruder (Plastacoder manufactured by Brabender, screw rotation speed 40 rpm, cylinder temperature 100 ° C), an isosceles triangle with an apex angle of about 30 ° C inscribed in a circle with a radius of about 14 mm When the rubber composition is extruded for 20 seconds from a die that approximates the radius of curvature of the apex (0.25 mm), the degree of edge breakage of the extrudate is evaluated by 5 panelists on a 5-point scale, and the average value is obtained. Asked. A larger score means better extrudability.

Exothermic (tan δ)
Based on JIS K6394, the obtained test piece was measured for tan δ at a temperature of 20 ° C. under the conditions of an initial strain of 10%, an amplitude of ± 2%, and a frequency of 20 Hz using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho. . The obtained results are shown in Tables 2 and 3 in terms of an index where the reciprocal of the value of the standard example is 100. The larger the index, the smaller the exotherm and the better.

Abrasion resistance In accordance with JIS K6264, the obtained test piece was worn under the conditions of a temperature of 25 ° C., a load of 30 N, a slip rate of 30%, and a time of 10 minutes using a lambone wear tester (manufactured by Iwamoto Seisakusho). The amount was measured. The obtained results are shown in Tables 2 and 3 in terms of an index where the reciprocal of the value of the standard example is 100. A larger index means better wear resistance.

The types of raw materials used in Tables 1, 2, and 3 are shown below.
NR: natural rubber, RSS # 3
BR: butadiene rubber, NIPOL BR 1220 manufactured by Nippon Zeon Co., Ltd.
VCR: butadiene rubber containing syndiotactic-1,2-polybutadiene, UBEPOL VCR412 manufactured by Ube Industries, Ltd. (the content of syndiotactic-1,2-polybutadiene is 12% by weight)
CB-1 to CB-4: Carbon black prototype 1 to prototype 4, each carbon black having colloidal characteristics shown in Table 1 is a combustion in which a tangential air supply port and a furnace axial direction are attached to the furnace head A combustion chamber (400 mm in diameter and 500 mm in length) provided with a burner and a raw oil spray nozzle is provided, a front-stage narrow reaction chamber (diameter 180 mm, length 500 mm) and a rear-stage reaction chamber (diameter 150 mm) connected coaxially with the combustion chamber. , Length 1000mm) and a continuous large diameter reaction chamber (diameter 300mm), using an oil furnace furnace, feedstock feed position, feedstock feed quantity, feed pressure and temperature, total air flow, reaction stop The generation conditions such as the cooling water introduction position were appropriately prepared and manufactured.
CB-5: Carbon black, Toast Carbon Co., Ltd. Seest KH (N339)
CB-6: Carbon black, Show Black N220 manufactured by Showa Cabot Corporation
CB-7: Carbon black, Seast N made by Tokai Carbon
Anti-aging agent: Antigen RD-G manufactured by Sumitomo Chemical Co., Ltd.
Zinc Hana: Zinc Oxide Type 3 manufactured by Shodo Chemical Industry Co., Ltd. Stearic Acid: Beads manufactured by Nippon Oil & Fats Co., Ltd. Sulfur Stearate: Kristec HS OT 20 manufactured by Akzo Nobel
Vulcanization accelerator: NOCELLER DM manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Claims (2)

30 to 50 parts by weight of carbon black is blended with 100 parts by weight of diene rubber containing 20 to 70% by weight of butadiene rubber containing syndiotactic-1,2-polybutadiene, and the nitrogen adsorption specific surface area N _{2 of the} carbon black SA ^[m 2 / g] and an iodine adsorption amount IA [mg / g] ratio _N 2 SA / IA with the from 1.10 to 1.30, DBP absorption amount 50~70cm ³ / 100g, CTAB adsorption specific surface area The rubber composition for tires whose is 80-100 m < ² > / g.   The pneumatic tire which comprised the sidewall part with the rubber composition for tires of Claim 1.