JP2010150324A - Tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire with improved dumping performance. <P>SOLUTION: The tire 1 which used a rubber composition containing 40-80 pts.mass of a magnetic filler in the base tread portion 2b based on 100 pts.mass of at least a kind of rubber component selected from a group composed of a natural rubber, a butadiene rubber and a styrene butadiene rubber, is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tire using a rubber composition containing a magnetic filler.

  In order to improve steering stability, which is an important required characteristic of automobiles, conventionally, a rubber composition for a bead apex or a tread portion constituting a tire has been used with a relatively high rigidity and hardness. However, when the rigidity of the rubber composition is increased, there arises a problem that ride comfort and road noise increase.

  It is also an important requirement to reduce the rolling resistance of the tire and reduce the fuel consumption of the automobile. As a method of making a tire tread low heat build-up, a method of reducing the amount of reinforcing filler in the rubber composition forming the tread is known. In this case, the hardness of the rubber composition is low. As a result, the tire tread is softened, resulting in a problem that the steering stability of the vehicle and the wear resistance of the tire are lowered.

  Therefore, as a method for solving this problem, silica or the like has been used for the filler. For example, Patent Document 1 proposes a rubber composition for a tread in which a composite material of starch and a plasticizer is blended together with silica. The rubber composition is formed by vulcanizing the rubber composition. There has been a problem that the wear resistance of a tire having a tread is not sufficient.

Further, Patent Document 2 discloses a rubber composition for a tire having improved steering stability without impairing basic characteristics such as rubber hardness, dynamic elastic modulus, and wear resistance of a tire, and a kraft paper crushed material as a rubber component. A rubber composition containing calcium carbonate has been proposed. However, further improvement in performance is required.
JP 2003-192832 A JP 2006-117715 A

  An object of this invention is to provide the tire which can aim at the improvement of steering stability and riding comfort (damping property).

  The present invention provides a base tread portion comprising a rubber composition containing 40 to 80 parts by mass of a magnetic filler with respect to 100 parts by mass of a rubber component which is at least one selected from the group consisting of natural rubber, butadiene rubber and styrene butadiene rubber. The tire used.

  The present invention uses a rubber composition containing 40 to 80 parts by mass of a magnetic filler for a clinch apex with respect to 100 parts by mass of a rubber component which is at least one selected from the group consisting of natural rubber, butadiene rubber and styrene butadiene rubber. Tire.

  The present invention uses, for a bead apex, a rubber composition containing 40 to 80 parts by mass of a magnetic filler with respect to 100 parts by mass of at least one rubber component selected from the group consisting of natural rubber, butadiene rubber and styrene butadiene rubber. Tire.

In the tire of the present invention, the magnetic filler preferably has an average particle size of 200 μm or less, a specific surface area of 1.5 g / cm ² or more, and a compression density of 4 g / cm ³ or less.

  In the tire of the present invention, the magnetic filler preferably contains at least one selected from the group consisting of a ferrite magnet, a rare earth magnet, γ iron oxide, chromium dioxide, metal magnetic powder, and a cobalt-chromium alloy.

  In the tire of the present invention, the magnetic filler is preferably magnetized in advance or magnetized after vulcanization.

  In the tire of the present invention, it is preferable that the magnetic filler has a spherical shape, a needle shape, a hexagonal plate shape, a flake shape, or an indeterminate shape.

  According to the present invention, by applying a rubber composition containing a magnetic filler to a base tread portion, a clinch apex, and a bead apex of a tire, it is possible to improve both handling stability and riding comfort (damping property). it can.

<Tire structure>
The tire of the present invention is obtained using a rubber composition in which a magnetic filler is blended with a base tread portion, a clinch apex, and a bead apex. That is, the tire of the present invention includes any conventionally known tire as long as it has such a base tread portion, clinch apex, and bead apex.

  Such a tire 1 includes, for example, a tread portion 2 including a cap tread portion 2a and a base tread portion 2b, and a pair of sides extending inward in the tire radial direction from both ends of the tread portion 2, as shown in FIG. In general, it has a structure including a wall portion 3 and a bead portion 4 positioned at the inner end of each sidewall portion 3. A carcass 6 is bridged between the bead portions 4, and a belt layer 7 that reinforces the tread portion 2 with a tagging effect is disposed outside the carcass 6 and inside the tread portion 2. .

  The carcass 6 is formed of one or more carcass plies 6a in which the carcass cord is arranged at an angle of, for example, 70 to 90 ° with respect to the tire equator CO. The carcass ply 6a extends from the tread portion 2 to the sidewall portion. 3, the periphery of the bead core 5 of the bead portion 4 is folded back and locked from the inner side to the outer side in the tire axial direction.

  The belt layer 7 is composed of two or more belt plies 7a in which the belt cord is arranged at an angle of, for example, 40 ° or less with respect to the tire equator CO. It is location.

  Further, a bead apex rubber 8 extending radially outward from the bead core 5 is disposed in the bead portion 4, and an inner liner rubber 9 forming a tire lumen surface is adjacent to the inside of the carcass 6. The outside of the carcass 6 is protected by the clinch apex rubber 4G and the side wall rubber 3G.

  The tire of the present invention is obtained by using a rubber composition in which a magnetic filler is blended with the base tread portion 2b, the clinch apex rubber 4G, and the bead apex 8.

<Rubber composition>
The rubber composition used in the tire of the present invention includes at least one rubber component selected from the group consisting of natural rubber, butadiene rubber, and styrene butadiene rubber, and a magnetic filler.

<Rubber component>
As the rubber component, natural rubber, butadiene rubber and styrene butadiene rubber can be used. These rubber components may be used alone or in combination of two or more. In particular, when used in tire base treads, clinch apex and bead apex, it exhibits excellent rigidity, ride comfort (damping performance) and durability performance, so the rubber component may consist of natural rubber and butadiene rubber. preferable.

<Magnetic filler>
In the present invention, the magnetic filler means a filler of magnetic fine particles, and the fine particles preferably do not contain a core material such as inorganic porous particles from the viewpoint of preventing a decrease in tensile strength.

  Specific examples of the magnetic filler include ferrite magnets, rare earth magnets, γ iron oxide, chromium dioxide, metal magnetic powder, and cobalt-chromium alloy. Examples of ferrite magnets include ferrite, barium ferrite, strontium ferrite, manganese zinc ferrite, nickel zinc ferrite, and copper zinc ferrite. Specific examples of rare earth elements used in rare earth magnets include samarium and neodymium. Among these, ferrite and strontium ferrite are preferable in terms of high magnetic force and low cost.

  The average particle size of the magnetic filler is preferably 200 μm or less from the viewpoint that it does not become a fracture nucleus and wear resistance does not deteriorate.

The specific surface area of the magnetic filler is preferably 1.5 g / cm ² or more, for example, and preferably 300 g / cm ² or less.

Compressed density of the magnetic filler is preferably from 4g / cm ³ or less, 3.5 g / cm ³ or less is more preferable. Further, the compression density of the magnetic filler is preferably 0.5 g / cm ³ or more, and more preferably 1.0 g / cm ³ or more.

  The magnetic flux density of the magnetic filler is preferably 100 G (Gauss) or more, and more preferably 1000 G or more. Further, the magnetic flux density of the magnetic filler is preferably 3000 G or less, and more preferably 2000 G or less.

  The content of the magnetic filler is preferably 40 parts by mass or more and more preferably 50 parts by mass or more with respect to 100 parts by mass of the rubber component from the viewpoint of improving tan δ. Further, the content of the magnetic filler is preferably 80 parts by mass or less and more preferably 70 parts by mass or less with respect to 100 parts by mass of the rubber component because of excellent wear resistance.

  Examples of the shape of the magnetic filler include a spherical shape, a needle shape, a hexagonal plate shape, a flake shape, and an indeterminate shape. Among these, the spherical shape is preferable from the viewpoint of not having anisotropy in tensile strength.

  The magnetic filler may be a magnetic filler magnetized in advance, or may be magnetized after vulcanization. The method of magnetizing after vulcanization is not particularly limited. For example, a method of attaching an electromagnet to a tire vulcanization mold and magnetizing the magnetic filler with the magnet can be mentioned.

  By containing the magnetic filler, the rubber composition of the present invention can generate high tan δ by repeatedly attracting and repelling each other by the magnetic force of the magnetic filler. Generally, when tan δ (hysteresis loss) is large, the response to an external force becomes gentle, and as a result, the ability to absorb the external force increases. As a result, the riding comfort (damping performance) of the tire can be improved.

<Carbon black>
The rubber composition used for the tire of the present invention can further contain a reinforcing filler. The reinforcing fillers may be used alone or in combination of two or more. Examples of the reinforcing filler include carbon black, silica, calcium carbonate, magnesium oxide and the like, and carbon black is preferable because of its large reinforcing effect.

  The content of carbon black is preferably 10 to 200 parts by mass and more preferably 20 to 150 parts by mass with respect to 100 parts by mass of the rubber component. When the content of carbon black is less than 10 parts by mass, the wear resistance tends to decrease. Moreover, when it exceeds 200 mass parts, there exists a tendency for workability to deteriorate.

Nitrogen adsorption specific surface area of carbon black is preferably 80~280m ² / g, more preferably 100 to 200 m ² / g. When the nitrogen adsorption specific surface area is less than 80 m ² / g, grip performance and wear resistance tend to be lowered. On the other hand, if the nitrogen adsorption specific surface area exceeds 280 m ² / g, good dispersion is difficult to obtain, and the workability tends to decrease.

<Anti-aging agent>
The rubber composition used for the tire of the present invention preferably further contains an 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.

  The content of the anti-aging agent is preferably 0.1 to 20 parts by mass and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. When the content of the anti-aging agent is less than 0.1 parts by mass, the anti-aging effect tends to be small. Moreover, when it exceeds 20 mass parts, there exists a tendency for tire performance to deteriorate.

<Softener>
Softeners include petroleum-based softeners such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt and petroleum jelly, and fatty oil-based softeners such as soybean oil, palm oil, castor oil, linseed oil, rapeseed oil and coconut oil. Agent, wax such as sub oil, beeswax, carnauba wax, lanolin, fatty acids such as linoleic acid, palmitic acid, stearic acid, lauric acid, coumarone resin, petroleum resin, phenolic resin, terpene resin, xylene resin, etc. Resin etc. are mentioned.

  When oil is contained, the oil content is preferably 10 to 200 parts by mass, more preferably 20 to 150 parts by mass, including oil-extended oil, with respect to 100 parts by mass of the rubber component. . If the oil content is less than 10 parts by mass, the wet grip performance tends to be insufficient. Moreover, when it exceeds 200 mass parts, there exists a tendency for abrasion resistance to fall remarkably.

  The softening point of the resin is preferably 40 to 200 ° C, and more preferably 60 to 180 ° C. If the softening point of the resin is less than 40 ° C., the grip performance under high temperature conditions tends to decrease. When the temperature exceeds 200 ° C., the dispersibility during kneading tends to decrease.

  When the resin is blended, the content of the resin is preferably 1 to 50 parts by mass, and more preferably 5 to 30 parts by mass with respect to 100 parts by mass of the rubber component. If the resin content is less than 1 part by mass, grip performance tends to be insufficient. Moreover, when it exceeds 50 mass parts, since it shows excessive adhesiveness, there exists a tendency for a process to become difficult.

  For reasons of excellent grip performance, it is preferable to use an oil and a resin in combination.

<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, 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 or 1,3-bis (t-butylperoxypropyl) benzene or the like can be used. 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.

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

<Other additives>
In the rubber composition used in the present invention, additives such as an ozone degradation inhibitor can be blended in addition to the above components.

<Method for producing rubber composition>
The rubber composition used in the tire of the present invention is prepared by first mixing a rubber component and a magnetic filler, and then weighing the remaining compounding agent so as to have a predetermined compounding ratio, and then kneading the rubber such as an open roll or a Banbury mixer. There is a method of kneading at 100 to 250 ° C. for 5 to 60 minutes using an apparatus.

<Tire manufacturing method>
The tire of the present invention is manufactured by a usual method. That is, the rubber composition is extruded in accordance with the shape of each member (base tread portion, clinch apex, bead apex) of the tire at an unvulcanized stage, and is molded by a normal method on a tire molding machine. Thus, an unvulcanized tire is formed. The unvulcanized tire can be heated and pressurized in a vulcanizer to obtain a tire.

<Examples 1-12, Comparative Examples 1-3>
<Preparation of rubber composition>
According to the formulation shown in Table 1, chemicals other than sulfur and vulcanization accelerator were kneaded for 3 minutes at 150 ° C. using a Banbury mixer to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded material, and kneaded for 5 minutes under the condition of 100 ° C. using an open roll, to obtain unvulcanized rubber compositions A to E.

  Furthermore, the unvulcanized rubber composition was press-vulcanized for 30 minutes under the condition of 150 ° C., and vulcanized rubber sheets A to E of Examples 1 to 4 and Comparative Example 1 were produced. The following tests were performed on the vulcanized rubber sheet.

(Viscoelasticity test)
Using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. under conditions of initial strain 10%, frequency 5 Hz, dynamic strain 2% at 100 ° C. and complex elastic modulus E ′ (unit: MPa) and loss tan δ Was measured. With respect to each of the complex elastic modulus E ′ and the loss tan δ, the value of the vulcanized rubber sheet E was set to 100, and the measured values of the respective blends were indicated by indices according to the following formulas.

(Complex elastic modulus index) = (E ′ of each compound) / (E ′ of vulcanized rubber sheet E) × 100
(Tan δ index) = (tan δ of each compound) / (tan δ of vulcanized rubber sheet E) × 100
The larger the complex modulus index, the better the rigidity, and the larger the tan δ index, the more responsive to external force, the better the ride comfort (damping performance).

(Tensile test)
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 sheet. By this test, 300% elongation stress (M300, unit: MPa) was measured for each vulcanized rubber sheet. The M300 of the vulcanized rubber sheet E was set to 100, and the measured value of each compound was indicated by an index according to the following formula. It shows that fracture strength is improving, so that a tensile strength index is large.

(Tensile strength index) = (M300 of each formulation) / (M300 of vulcanized rubber sheet E) × 100
The results are shown in Table 1.

NR: TSR
BR: Nippon 1220 manufactured by Nippon Zeon Co., Ltd. (Hicis BR, cis content 96.5%)
Carbon Black: Show Black N220 (N ₂ SA: 111 m ² / g) manufactured by Cabot Japan
Magnetic filler: Ferada powder FA700 manufactured by Toda Kogyo Co., Ltd. (average particle size: 1.25 μm, specific surface area: 1.70 m ² / g, compression density: 3.44 g / m ³ , magnetic flux density: 2920 G)
Oil: Process oil manufactured by Idemitsu Kosan Co., Ltd .: Sunnock wax anti-aging agent manufactured by Ouchi Shinsei Chemical Co., Ltd. 6C: Nocrack 6C (N- (1,3-dimethyl) manufactured by Ouchi Shinsei Chemical Co., Ltd. Butyl) -N'-phenyl-p-phenylenediamine)
Stearic acid: Zinc stearate manufactured by Nippon Oil & Fats Co., Ltd .: Zinc Hua No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd .: Ouchi Shinsei Chemical Industry Co., Ltd. ) Noxeller NS made
<Production of tire>
By molding an unvulcanized rubber composition into a base tread shape, a clinch apex shape, and a bead apex shape, and bonding each to other tire members, press vulcanization for 12 minutes at 170 ° C. 7. 10-5 size cart tires were prepared. The obtained tire is the tire which used the rubber composition of each compounding for the base tread part, the tire used for the clinch apex, and the bead apex. The following tests were conducted for each tire.

(Ride comfort)
The tire prepared in the cart was mounted, and the test course of 1 lap 2 km was run 8 laps. The damping performance (riding comfort) of the tire of Comparative Example 1 was set to 3 points, and the test driver made a sensory evaluation with 5 points. The higher the score, the better the ride and the higher the damping performance.

(Maneuvering stability)
Tires made on the cart were installed and the vehicle was run on a dry asphalt road test course, and the steering stability was evaluated by evaluating the rigidity and feeling of the driver when changing lanes. The evaluation has five levels, with 5 being the best performance and 1 being the worst.

  The results are shown in Table 2.

<Evaluation results>
(Physical properties of vulcanized rubber sheet)
Each of the vulcanized rubber sheets A to D has a magnetic filler content of 40 parts by weight, 50 parts by weight, 70 parts by weight, and 80 parts by weight with respect to 100 parts by weight of the rubber component. As the content of the magnetic filler increased, the tan δ index improved, but the tensile strength index decreased.

(Actual vehicle performance)
In each of Examples 1 to 12, the ride comfort could be improved while maintaining steering stability.

It is a schematic sectional drawing which shows an example of the pneumatic tire of this invention.

Explanation of symbols

  1 tire, 2 tread part, 2a cap tread part, 2b base tread part, 3 sidewall part, 4 bead part, 5 bead core, 6 carcass, 7 belt layer, 8 bead apex rubber, 9 inner liner rubber, 4G clinch rubber.

Claims (7)

  A tire using, as a base tread portion, a rubber composition containing 40 to 80 parts by mass of a magnetic filler with respect to 100 parts by mass of a rubber component which is at least one selected from the group consisting of natural rubber, butadiene rubber and styrene butadiene rubber.   A tire using, as a clinch apex, a rubber composition containing 40 to 80 parts by mass of a magnetic filler with respect to 100 parts by mass of a rubber component which is at least one selected from the group consisting of natural rubber, butadiene rubber and styrene butadiene rubber.   A tire using, as a bead apex, a rubber composition containing 40 to 80 parts by mass of a magnetic filler with respect to 100 parts by mass of a rubber component which is at least one selected from the group consisting of natural rubber, butadiene rubber and styrene butadiene rubber. The tire according to any one of claims 1 to 3, wherein the magnetic filler has an average particle size of 200 µm or less, a specific surface area of 1.5 g / cm ² or more, and a compression density of 4 g / cm ³ or less. The tire according to any one of claims 1 to 3, wherein the magnetic filler includes at least one selected from the group consisting of a ferrite magnet, a rare earth magnet, γ iron oxide, chromium dioxide , metal magnetic powder, and a cobalt-chromium alloy. .   The tire according to any one of claims 1 to 3, wherein the magnetic filler is magnetized in advance or magnetized after vulcanization.   The tire according to any one of claims 1 to 3, wherein the magnetic filler has a spherical shape, a needle shape, a hexagonal plate shape, a flake shape, or an indeterminate shape.

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