JP2010159375A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition giving a tire with sufficient reinforcing properties, low fuel consumption, rigidity and high severity abrasion resistance at low cost. <P>SOLUTION: The rubber composition includes 5-75 pts.mass of pulverized bituminous coal and 2-8 pts.mass of petroleum-based resin, each based on 100 pts.mass of diene rubber. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubber composition and a tire having a base tread and / or clinch using the rubber composition.

  In recent years, as the required performance of tires has increased, cost reduction has also been demanded. As a method for reducing the cost, it is conceivable to add an inorganic filler such as calcium carbonate. However, since the reinforcing property of calcium carbonate is inferior to that of carbon black, the breaking strength of the rubber is impaired. Moreover, since calcium carbonate has a large specific gravity of 2.7, there is a concern that the weight of the entire tire increases and the fuel consumption of the vehicle deteriorates.

  On the other hand, the clinch portion, which is a chafering portion with the rim, is a tire component that receives a heavy load and a very strong thermal history. Therefore, it is necessary to use a rubber composition having high strength and high wear resistance that can withstand heavy loads for the clinch portion.

  Patent Document 1 discloses a method of blending bituminous coal pulverized material or bituminous coal pulverized material and calcium carbonate as means for reducing the cost of the tire. However, there is room for further improvement in terms of reinforcement and rigidity.

JP 2007-153060 A

  An object of this invention is to provide the rubber composition which can obtain the tire which has sufficient reinforcement property, low fuel consumption, rigidity, and high-severity abrasion resistance at low cost.

  The present invention is a rubber composition in which 5 to 75 parts by mass of a bituminous coal pulverized product and 2 to 8 parts by mass of a petroleum resin are blended with 100 parts by mass of a diene rubber.

  In the rubber composition of the present invention, the pulverized bituminous coal preferably has an average particle size of 0.1 mm or less and a specific gravity of 1.4 or less.

The present invention is a pneumatic tire having a base tread using the rubber composition.
The present invention is a pneumatic tire having a clinch using the rubber composition.

  ADVANTAGE OF THE INVENTION According to this invention, the rubber composition which can obtain the tire which has sufficient reinforcement property, low fuel consumption, rigidity, and high severe abrasion resistance at low cost can be provided.

It is a figure which shows the right half of sectional drawing of the tire which concerns on this invention.

<Rubber composition>
The rubber composition according to the present invention includes a diene rubber, a bituminous coal pulverized product, and a petroleum resin.

<Diene rubber>
Diene rubbers include natural rubber (NR), polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR). ), Styrene-isoprene-butadiene copolymer rubber (SIBR), ethylene-propylene-diene rubber (EPDM) and the like, and rubber components containing one or more of these are preferred.

<Mineralized bituminous coal>
The bituminous coal contained in the rubber composition of the present invention includes general coal. Such bituminous coal is contained in the rubber composition as a pulverized product.

  Since the bituminous coal pulverized product contains carbon and has good compatibility with the diene rubber component, the diene rubber can be reinforced. In addition, since the bituminous coal pulverized product contains an oil component, it has good dispersibility in the diene rubber, and is unlikely to generate an agglomerate that causes a decrease in strength. Bituminous coal pulverized products are available at low cost.

  The bituminous coal pulverized product is blended in an amount of 5 to 75 parts by mass, preferably 10 to 60 parts by mass, and more preferably 20 to 40 parts by mass with respect to 100 parts by mass of the diene rubber. There are few cost merit as the compounding quantity of a bituminous coal ground material is less than 5 mass parts. On the other hand, when the blending amount of the bituminous coal pulverized product exceeds 75 parts by mass, the breaking strength and breaking elongation are lowered, and the cut tip performance cannot be improved when used in the base tread portion. Also, the complex elastic modulus is lowered, and the required rigidity cannot be obtained when used for clinch.

  The average particle size of the bituminous coal pulverized product is 0.1 mm or less, preferably 0.05 mm or less. By setting the average particle size to 0.1 mm or less, the rubber composition can be favorably dispersed, so that the strength of the resulting rubber composition can be improved.

  The specific gravity of the bituminous coal pulverized product is preferably 1.4 or less, and more preferably 1.1 or less. By setting the specific gravity to 1.4 or less, the specific gravity of the entire rubber composition can be reduced, and the fuel consumption of a vehicle body equipped with a tire using the rubber composition can be sufficiently reduced.

<Carbon black>
The rubber composition of the present invention preferably contains a reinforcing filler. The reinforcing filler can be arbitrarily selected from those conventionally used in rubber compositions for tires, but carbon black is mainly preferred.

  Carbon black is not particularly limited, and those generally used for general-purpose rubber can be used. As the carbon black, for example, channel black such as HAF, ISAF, or SAF, furnace black, acetylene black, or thermal black can be used.

Carbon black, for example, has an agglomerated size and porosity such that the nitrogen adsorption specific surface area is 50 to 200 m ² / g, the 24M4 DBP oil absorption is 50 to 130 ml / 100 g, and the CTAB adsorption specific surface area is 50 to 170 m ² / g. It is particularly preferable to have it. In this case, the rubber composition does not become too hard and sufficient abrasion resistance can be obtained. Moreover, it is preferable to use a specific gravity of 1.5 to 1.9.

  10-150 mass parts is preferable with respect to 100 mass parts of diene rubbers, and, as for the compounding quantity of carbon black, it is more preferable that it is 15-100 mass parts. Wear resistance can be improved by setting the blending amount of carbon black to 10 parts by mass or more, and an increase in heat generation can be suppressed by setting it to 150 parts by mass or less.

<Petroleum resin>
The petroleum-based resin contained in the rubber composition of the present invention is not particularly limited, but an aliphatic petroleum resin, a coumarone resin, an alicyclic petroleum resin, an aromatic petroleum resin, or the like is used. Can do. Of these, alicyclic petroleum resins are preferred. By blending the petroleum-based resin, the cut-chip resistance is improved, so that the durability of the tire can be improved.

  The compounding quantity of petroleum-type resin is 2-8 mass parts with respect to 100 mass parts of diene rubbers, and 3-8 mass parts is preferable. When the blending amount of the petroleum-based resin is less than 1 part by mass, the breaking strength is lowered, and the cut chip performance cannot be improved when used in the base tread part. In addition, the rigidity cannot be improved when used in the clinch portion. On the other hand, when the blending amount of the petroleum resin exceeds 8 parts by mass, the rolling resistance is deteriorated and the heat generation of the tire is increased. Further, when used in the clinching portion, the high severe wear resistance deteriorates.

<Softener>
In the present invention, a softener may be used in combination in order to further improve kneading processability. Softeners include process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petroleum jelly such as petroleum jelly, fatty oil softener such as castor oil, linseed oil, rapeseed oil, coconut oil, tall oil, , Waxes such as beeswax, carnauba wax and lanolin, and fatty acids such as linoleic acid, palmitic acid, stearic acid and lauric acid.

<Anti-aging agent>
As the anti-aging agent, amine-based, phenol-based, and imidazole-based compounds, carbamic acid metal salts, waxes, and the like can be appropriately selected and used.

<Vulcanization aid>
As the vulcanization aid, stearic acid, zinc oxide (zinc white) or the like can be used.

<Vulcanizing agent>
As the vulcanizing agent, an organic peroxide or a sulfur vulcanizing agent can be used. Examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, and 2,5-dimethyl-2,5. -Di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 Alternatively, 1,3-bis (t-butylperoxypropyl) benzene, di-t-butylperoxy-diisopropylbenzene, t-butylperoxybenzene, 2,4-dichlorobenzoyl peroxide, 1,1-di-t -Butylperoxy-3,3,5-trimethylsiloxane, n-butyl-4,4- And the like can be used -t- butyl peroxy valerate. Of these, dicumyl peroxide, t-butylperoxybenzene and di-t-butylperoxy-diisopropylbenzene are preferred. Moreover, as a sulfur type vulcanizing agent, sulfur, morpholine disulfide, etc. can be used, for example. Of these, sulfur is preferred.

<Vulcanization accelerator>
Vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Those containing at least one of them can be used.

<Other ingredients>
In addition to the above, the rubber composition of the present invention is appropriately blended with compounding agents used in the normal rubber industry, such as reinforcing agents such as silica, plasticizers, foaming agents, scorch inhibitors, and processing aids. be able to.

<Method for producing rubber composition>
The rubber composition of the present invention can be produced by a commonly used known method, and a mixture of the rubber composition in the above-mentioned blending amount is kneaded using a rubber kneading apparatus such as a Banbury mixer or an open roll. A method of vulcanizing at 140 to 150 ° C. for 25 to 35 minutes can be used.

<Tire structure>
The structure of the tire of the present invention is exemplified in the upper right half of the tire cross section in FIG. The tire 1 includes a cap tread rubber 7a and a base tread rubber 7b constituting the tread portion 7, a side wall rubber 8 constituting a pair of sidewall portions extending inward in the tire radial direction from both ends thereof, and an inner portion of each sidewall portion. A clinch rubber 3 constituting a clinch portion located at one end and a chafer rubber 2 constituting a chafer located at the upper portion of the rim. A carcass 5 is bridged between the clinch portion and the chafer, and a breaker rubber 9 constituting a breaker portion is disposed outside the carcass 5 in the tire radial direction. The carcass 5 is formed of one or more carcass plies on which carcass cords are arranged. The carcass ply includes a bead core 6 extending from a tread portion through a sidewall portion and an upper end of the bead core 6 toward the sidewall. The area around the apex 4 is folded from the inner side to the outer side in the tire axial direction, and is locked by the folded portion. The breaker portion is composed of two or more breaker plies in which breaker cords are arranged, and the breaker cords are stacked in different directions so that the breaker cords intersect each other.

  The tire of the present invention is obtained by using a rubber composition obtained by blending a base tread rubber 7b and / or a clinch rubber 3 with a bituminous coal pulverized product and a petroleum resin. That is, the tire of the present invention includes a tire having any conventionally known structure as long as such a base tread and / or clinch is provided.

<Tire manufacturing method>
A tire using the rubber composition according to the present invention is prepared by kneading the compounding components of the rubber composition at 130 ° C. or higher and 160 ° C. or lower with, for example, a Banbury mixer or a kneader to prepare an uncrosslinked product of the rubber composition. The uncrosslinked product can be formed by applying it to a base tread portion and / or a clinch portion of a tire and performing vulcanization molding.

<Preparation of rubber composition>
Of the blending components shown in Table 1, the components excluding sulfur and the vulcanization accelerator were kneaded at about 150 ° C. for 5 minutes using a banbury, further added with sulfur and the vulcanization accelerator, and about 80 using a biaxial open roll. An unvulcanized rubber composition was obtained by kneading at 5 ° C. for 5 minutes. A rubber sheet was prepared using the unvulcanized rubber composition, and vulcanized under conditions of 150 ° C., 35 minutes, 25 kgf (245.16625N) to prepare a vulcanized rubber composition. The following measurements were performed on the obtained vulcanized rubber composition.

[Example 1, Comparative Examples 1 to 5]
For the vulcanized rubber compositions of Example 1 and Comparative Examples 1 to 5, the following measurements were performed in order to evaluate the applicability to the base tread. Comparative example 5 is a conventional example.

<Cost>
The cost was evaluated by a method of calculating the blending cost by multiplying each material unit price by the used mass of each material, and indexed with Comparative Example 5 as 100. The smaller the value, the better the cost reduction effect.

<Specific gravity>
The index is shown by setting the specific gravity of the vulcanized rubber composition of Comparative Example 5 to 100, and the smaller the index is, the lower the specific gravity is.

<Breaking strength, breaking elongation>
In accordance with JIS K 6251 “Vulcanized Rubber and Thermoplastic Rubber—How to Obtain Tensile Properties”, evaluation was performed using a No. 3 dumbbell type rubber test piece made of the vulcanized rubber composition. With respect to the vulcanized rubber composition of each formulation, the breaking strength TB (MPa) and the breaking elongation EB (%) were measured, and Comparative Example 5 was set to 100, and each compounding was indexed using the following formula. Both the breaking strength index and the breaking elongation index indicate that the larger the value, the better the strength.

(Break strength index) = (Break strength of each formulation) / (Break strength of Comparative Example 5) × 100
(Elongation at break) = (Elongation at break for each formulation) / (Elongation at break in Comparative Example 5) × 100
<Rolling resistance>
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), tan δ of each vulcanized rubber composition was measured under conditions of a temperature of 70 ° C., an initial strain of 10%, and a dynamic strain of 2%. Using tan δ of Comparative Example 5 as 100, the vulcanized rubber composition of each compound was indexed using the following calculation formula. The larger the value, the lower the rolling resistance and the lower the fuel consumption.

(Rolling resistance index) = (tan δ of Comparative Example 5) / (tan δ of each formulation) × 100
The results are shown in Table 1.

[Example 2, Comparative Examples 6 to 10]
In order to evaluate the applicability to clinch for the vulcanized rubber compositions of Example 2 and Comparative Examples 6 to 10, the following measurements were performed. Comparative example 10 is a conventional example.

<Cost>
The cost was evaluated by a method of calculating the blending cost by multiplying the material unit price by the used mass of each material, and indexed with Comparative Example 10 as 100. The smaller the value, the better the cost reduction effect.

<Specific gravity>
The index is shown by setting the specific gravity of the vulcanized rubber composition of Comparative Example 10 to 100, and the smaller the index is, the lower the specific gravity is.

<Viscoelasticity test>
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the complex elastic modulus E * and tan δ of each vulcanized rubber composition were measured under the conditions of a temperature of 70 ° C., an initial strain of 10%, and a dynamic strain of 2%. It was measured. Using E * and tan δ of Comparative Example 10 as 100, the vulcanized rubber composition of each compound was indexed using the following calculation formula. The larger the complex modulus index, the higher the rigidity, and the larger the tan δ index, the greater the heat generation.

(Complex elastic modulus index) = (complex elastic modulus of each formulation) / (complex elastic modulus of Comparative Example 10) × 100
(Tan δ index) = (tan δ of each formulation) / (tan δ of Comparative Example 10) × 100
<Break strength>
In accordance with JIS K 6251 “Vulcanized Rubber and Thermoplastic Rubber—How to Obtain Tensile Properties”, evaluation was performed using a No. 3 dumbbell type rubber test piece made of the vulcanized rubber composition. For each vulcanized rubber composition, the breaking strength TB (MPa) was measured, and Comparative Example 10 was taken as 100, and each compound was indexed using the following formula. The larger the value, the better the strength.

(Break strength index) = (Break strength of each formulation) / (Break strength of Comparative Example 10) × 100
<High severity wear resistance>
Measurement was performed according to ASTM D228 using a pico abrasion tester. The measured value was expressed as an index using the following formula for each formulation, with the wear amount of Comparative Example 10 being 100. It shows that abrasion resistance is so favorable that a number is large.

(High Severity Abrasion Index) = (Abrasion amount of Comparative Example 10) / (Abrasion amount of each formulation) × 100
The results are shown in Table 2.

SBR: SBR1502 manufactured by Sumitomo Chemical Co., Ltd.
NR: Thai RSS # 3
BR: Ubepol BR-150B manufactured by Ube Industries, Ltd.
Carbon Black (1): Show Black N351 manufactured by Cabot Japan Co., Ltd. (nitrogen adsorption specific surface area: 64 m ² / g, 24M4 DBP oil absorption: 102 ml / 100 g)
Carbon black (2): N330 manufactured by Mitsubishi Chemical Corporation (nitrogen adsorption specific surface area: 78 m ² / g, 24M4 DBP oil absorption: 85 ml / 100 g, CTAB adsorption specific surface area: 78 m ² / g)
Bituminous coal pulverized product: Austin Black 325 made of coal filler (carbon content: 77%, average particle size: 5 μm, specific gravity: 1.31)
Process oil: Process NC300S made by Japan Energy
Petroleum resin: Marukaretsu T-100AS (Chemical name: Aliphatic C5 hydrocarbon resin) manufactured by Maruzen Petrochemical Co., Ltd.
Wax: Ozoace-0355 manufactured by Nippon Seiwa Co., Ltd.
Anti-aging agent: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Stearic acid: Tungsten zinc oxide manufactured by Nippon Oil & Fats Co., Ltd .: Zinc Hua No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd. Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide)
<Evaluation results>
Example 1 is a rubber composition containing 40 parts by mass of a bituminous coal pulverized product and 3 parts by mass of a petroleum-based resin with respect to 100 parts by mass of SBR. Compared with Comparative Example 5 (conventional example), the rolling resistance can be reduced and the cost can be reduced, which is suitable for application to a base tread.

  Comparative Example 1 is a rubber composition containing 4 parts by mass of a pulverized bituminous coal and 3 parts by mass of a petroleum resin with respect to 100 parts by mass of SBR. The content of the bituminous coal pulverized product is small, and the cost merit is small compared to Comparative Example 5 (conventional example).

  Comparative Example 2 is a rubber composition containing 80 parts by mass of a bituminous coal pulverized product and 3 parts by mass of a petroleum resin with respect to 100 parts by mass of SBR. The content of the bituminous coal pulverized material is large, and the breaking strength is greatly reduced as compared with Comparative Example 5 (conventional example), and the cut chip performance is deteriorated.

  Comparative Example 3 is a rubber composition containing 40 parts by mass of a bituminous coal pulverized product and 1 part by mass of a petroleum resin with respect to 100 parts by mass of SBR. The content of petroleum resin is small, the breaking strength is reduced as compared with Comparative Example 5 (conventional example), and the cut chip performance is deteriorated.

  Comparative Example 4 is a rubber composition containing 40 parts by mass of a bituminous coal pulverized product and 10 parts by mass of a petroleum-based resin with respect to 100 parts by mass of SBR. The content of petroleum-based resin is large, and rolling resistance is deteriorated as compared with Comparative Example 5 (conventional example).

  Example 2 is a rubber composition containing 40 parts by mass of a bituminous coal pulverized product and 3 parts by mass of a petroleum resin with respect to 100 parts by mass of a rubber component consisting of 40 parts by mass of NR and 60 parts by mass of BR. Compared with Comparative Example 10 (conventional example), the cost can be reduced without impairing the breaking strength and the high-severity wear resistance, which is suitable for application to clinch.

  Comparative Example 6 is a rubber composition containing 4 parts by mass of a pulverized bituminous coal and 3 parts by mass of a petroleum-based resin with respect to 100 parts by mass of a rubber component consisting of 40 parts by mass of NR and 60 parts by mass of BR. The content of the bituminous coal pulverized product is small, and the cost merit is small compared to Comparative Example 10 (conventional example).

  Comparative Example 7 is a rubber composition containing 80 parts by mass of a bituminous coal pulverized product and 3 parts by mass of a petroleum resin with respect to 100 parts by mass of a rubber component composed of 40 parts by mass of NR and 60 parts by mass of BR. The content of the bituminous coal pulverized material is large, and the complex elastic modulus and fracture strength are greatly reduced as compared with Comparative Example 10, and the required rigidity cannot be obtained.

  Comparative Example 8 is a rubber composition containing 40 parts by mass of a bituminous coal pulverized product and 1 part by mass of a petroleum resin with respect to 100 parts by mass of a rubber component consisting of 40 parts by mass of NR and 60 parts by mass of BR. The content of petroleum resin is small, the breaking strength is lower than that of Comparative Example 10 (conventional example), and the rigidity cannot be improved.

  Comparative Example 9 is a rubber composition containing 40 parts by mass of a bituminous coal pulverized product and 10 parts by mass of a petroleum resin with respect to 100 parts by mass of a rubber component consisting of 40 parts by mass of NR and 60 parts by mass of BR. Compared to Comparative Example 10 (conventional example), containing a large amount of petroleum resin. The tan δ value increases, heat generation increases, and high-severity wear resistance deteriorates.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 tire, 2 chafer rubber, 3 clinch rubber, 4 bead apex, 5 carcass, 6 bead core, 7 tread part, 7a cap tread rubber, 7b base tread rubber, 8 sidewall part, 9 breaker.

Claims (4)

  A rubber composition containing 5 to 75 parts by mass of a bituminous coal pulverized product and 2 to 8 parts by mass of a petroleum resin with respect to 100 parts by mass of a diene rubber.   The rubber composition according to claim 1, wherein the bituminous coal pulverized product has an average particle size of 0.1 mm or less and a specific gravity of 1.4 or less.   A pneumatic tire having a base tread using the rubber composition according to claim 1.   A pneumatic tire having a clinch using the rubber composition according to claim 1.

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