JP4882064B2 - Rubber composition for chafer and tire having chafer comprising the same - Google Patents

Description

  The present invention relates to a rubber composition for a chafer and a tire having a chafer made therefrom.

  In recent years, low flat tires have been developed for the purpose of improving handling performance and appearance. In addition, run-flat tires have been developed and are becoming popular due to safety during puncture.

  However, the tire has high rigidity, and when the tire is removed from the rim, damage to the contact portion (chafer) with the rim increases, and damage may occur. When the chafer is damaged, air leaks and the like occurs, resulting in a problem in safety. Therefore, it is necessary to improve the strength of the chafer rubber composition.

  Patent Document 1 discloses a rubber composition for a crawler in which a specific sulfide polymer is blended. However, the rubber strength of the chafer has not been improved by improving the rubber composition for the chafer.

JP 2005-48083 A

  An object of the present invention is to provide a rubber composition for a chafer with improved strength and a tire having a chafer comprising the same.

The present invention provides 40 to 120 parts by mass of a reinforcing agent and 100 parts by mass of the rubber component, and the general formula (1)
− (R−S _x ) _n − (1)
(Where R is

x is an integer of 3 to 6, n is an integer of 10 to 400, and m is an integer of 2 to 5)
It is related with the rubber composition for chafers containing 2-30 mass parts of compounds which satisfy | fill.

  The present invention also relates to a tire having a chafer made of the rubber composition for chafer.

  According to the present invention, the strength of the chafer can be greatly improved by using, as the chafer, the rubber composition for a side wall containing a polymer containing a sulfur atom in the molecule as a vulcanizing agent. Further, by improving the strength of the chafer, it is possible to prevent damage that occurs when a highly rigid tire such as a low flat tire or a run flat tire is removed from the rim.

The rubber composition for chafers of the present invention comprises a rubber component, a reinforcing agent, and a general formula (1).
− (R−S _x ) _n − (1)
(Where R is

x is an integer of 3 to 6, n is an integer of 10 to 400, and m is an integer of 2 to 5)
It consists of a compound satisfying the following (hereinafter referred to as Compound 1).

  As rubber components, natural rubber (NR), various butadiene rubbers (BR), styrene-butadiene copolymer rubber (SBR), isoprene rubber (IR), acrylonitrile-butadiene copolymer rubber (NBR), chloroprene rubber (CR), Examples thereof include diene rubbers such as styrene-isoprene-butadiene copolymer rubber (SIBR), styrene-isoprene copolymer rubber, and isoprene-butadiene copolymer rubber. These may be used singly or in combination of two or more, but NR and / or BR are preferred as the rubber component because an effect of improving rubber strength and fuel efficiency can be obtained.

  Examples of the reinforcing agent include silica, carbon black, talc, and clay. Of these, carbon black and silica are preferable, and carbon black is more preferable because an effect of improving reinforcing properties and fuel efficiency can be obtained.

When carbon black is used as the reinforcing agent, the nitrogen adsorption specific surface area (N ₂ SA) of the carbon black is preferably 35 m ² / g or more, and more preferably 40 m ² / g or more. When N ₂ SA is less than 35 m ² / g, the reinforcing property of rubber tends to be remarkably lowered. Further, N ₂ SA of carbon black is preferably 210 m ² / g or less, and more preferably 200 m ² / g or less. When N ₂ SA exceeds 210 m ² / g, the viscosity at the time of unvulcanization becomes very high, and the workability tends to deteriorate or the fuel consumption tends to deteriorate.

  Content of a reinforcing agent is 40 mass parts or more with respect to 100 mass parts of rubber components, Preferably it is 45 mass parts or more. When the content is less than 40 parts by mass, the reinforcing property of the rubber is deteriorated. Moreover, content of a reinforcing agent is 120 mass parts or less with respect to 100 mass parts of rubber components, Preferably it is 110 mass parts or less. When the content exceeds 120 parts by mass, the viscosity at the time of unvulcanization becomes high and the workability tends to deteriorate, or the fuel efficiency tends to deteriorate, which is not preferable.

Compound 1 used in the present invention has the general formula (1)
− (R−S _x ) _n − (1)
(Where R is

x is an integer of 3 to 6, n is an integer of 10 to 400, and m is an integer of 2 to 5)
Satisfied. In the present invention, compound 1 is used as a vulcanizing agent.

  In general formula (1), x is an integer of 3-6, Preferably it is an integer of 3-5. When x is less than 3, vulcanization is delayed, and when n exceeds 6, it becomes difficult to produce a rubber composition.

  In general formula (1), n is an integer of 10 to 400, preferably an integer of 10 to 300. If n is less than 10, compound 1 is easily volatilized and difficult to handle, and if n exceeds 400, compatibility with rubber deteriorates.

  In general formula (1), m is an integer of 2-5, preferably an integer of 2-4, more preferably an integer of 2-3. If m is less than 2, the bending performance of the obtained rubber composition tends to be lowered, and if m exceeds 5, the rubber composition tends not to have sufficient hardness.

  The content of Compound 1 is 2 parts by mass or more, preferably 2.5 parts by mass or more with respect to 100 parts by mass of the rubber component. If the content is less than 2 parts by mass, the rubber strength tends to deteriorate, which is not preferable. Moreover, content of the compound 1 is 30 mass parts or less with respect to 100 mass parts of rubber components, Preferably it is 28 mass parts or less. When content exceeds 30 mass parts, the intensity | strength of a chafer will fall.

  By compounding compound 1 in the rubber composition for chafers of the present invention, the following crosslinking units can be introduced into the rubber, and the reversion can be greatly improved without affecting the vulcanization speed and scorch. Can be suppressed. Further, it is possible to obtain heat resistance of a rubber composition that cannot be sufficiently obtained by general sulfur crosslinking and resistance to dynamic stress. Furthermore, since it is difficult to bloom, a rubber composition for a chafer that is excellent in appearance can be obtained.

  Compound 1 is preferably added and kneaded under the temperature condition of 80 to 130 ° C. in the production of the rubber composition. If the temperature is less than 80 ° C., sufficient kneading is not performed, and if the temperature exceeds 130 ° C., vulcanization is started, so that there is a problem that sufficient kneading is not performed.

  Compound 1 can also be used with a vulcanizing agent such as sulfur.

  The rubber composition for chafers of the present invention preferably contains a vulcanization accelerator together with the vulcanizing agent. As the vulcanization accelerator, a general sulfenamide-based one is used.

  The content of the vulcanization accelerator is preferably 0.3 to 15 parts by weight with respect to 100 parts by weight of the rubber component. When the content of the vulcanization accelerator is less than 0.3 parts by weight, sufficient vulcanization is not performed and the rubber strength tends to be remarkably reduced. On the other hand, when the content of the vulcanization accelerator exceeds 15 parts by weight, the vulcanization speed becomes very fast, which is not preferable from the viewpoint of workability, and the rubber strength tends to decrease.

  In addition to the rubber component, the reinforcing agent, the vulcanizing agent such as Compound 1 and the vulcanization accelerator, the rubber composition for chafer of the present invention, if necessary, a vulcanizing agent such as sulfur, a softening agent, Wax, anti-aging agent, stearic acid, zinc oxide and the like can be blended.

  The tire of the present invention preferably has a chafer made of the rubber composition. The tire of the present invention is obtained by kneading a material other than a vulcanizing agent and a vulcanization accelerator to obtain a kneaded product, and further adding a vulcanizing agent and a vulcanization accelerator to the kneaded material and kneading. It is preferable that the vulcanized rubber composition is molded into a chafer shape and bonded to another tire member to form an unvulcanized tire and vulcanized.

  The tire of the present invention is particularly preferably a run flat tire.

  FIG. 1 shows an example of a cross-sectional view of the right half of a cross-sectional view of a run-flat tire having a chafer made of the rubber composition for a chafer of the present invention. In FIG. 1, reference numeral 10 denotes a chafer, which is a portion in contact with the rim of the tire wheel.

  The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

Various chemicals used in the examples are described below.
NR: RSS # 3
BR: BR150B manufactured by Ube Industries, Ltd.
Carbon black: N330 (N ₂ SA: 79 m ² / g) manufactured by Showa Cabot Co., Ltd.
Process oil: Diana Process PS32 manufactured by Idemitsu Kosan Co., Ltd.
Wax: Sannoc Wax manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Anti-aging agent: Santoflex 13 manufactured by Flexis
Stearic acid: Tungsten zinc oxide manufactured by Nippon Oil & Fats Co., Ltd .: Zinc oxide No. 2 manufactured by Mitsui Metal Mining Co., Ltd. -Tetrasulfide (m = 2, x = 4, n = 200))

Vulcanization accelerator: Noxeller NS manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Examples 1-3 and Comparative Examples 1-2
The various chemicals except sulfur, compound 1 and vulcanization accelerator were kneaded at 150 ° C. for 5 minutes using the contents shown in Table 1 using 1.7 L Banbury manufactured by Kobe Steel. Sulfur, compound 1 and a vulcanization accelerator were added to the obtained kneaded product, and a rubber composition was prepared by vulcanizing the mixture kneaded at 105 ° C. for 3 minutes with a biaxial roller at 175 ° C. for 15 minutes. . The following tests were performed using the obtained rubber composition.

(Rim removal test)
A run flat tire (size 255 / 40R20) having a chafer made of the rubber composition was produced. The tire was removed from the rim using a normal tire changer and visually checked for damage to the chafer. When the tire was removed from the rim, it was evaluated as ○ when the chafer portion was not damaged, and × when there was damage such as a piece of rubber.

(Tear test)
In accordance with the test method of “Vulcanized rubber and thermoplastic rubber—How to determine tear strength” of JIS-K6252, the tear strength (kN / m) was measured.

  The test results are shown in Table 1.

  The rubber compositions of Examples 1 to 3 in which Compound 1 was blended in the range of 2 to 30 parts by mass improved the rubber strength as compared with Comparative Example 1 in which Compound 1 was not blended, and were further removed from the rim. There was no damage.

  On the other hand, the rubber composition of Comparative Example 2 containing 35 parts by mass of Compound 1 did not improve the rubber strength, and the chafer was damaged when removed from the rim.

It is the right half of sectional drawing of the run flat tire in one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tire 2 Side wall part 3 Carcass ply 4 Belt layer 5 Tread part 6 Bead core 7 Bead part 8 Side reinforcement layer 9 Bead apex 10 Chafer

Claims (2)

For 100 parts by mass of the rubber component,
40-120 parts by mass of reinforcing agent, and general formula (1)
− (R−S _x ) _n − (1)
(Where R is

x is an integer of 3 to 6, n is 200 , and m is an integer of 2 to 5)
The run flat tire which has a chafer which consists of a rubber composition for chafers containing 2-30 mass parts of compounds which satisfy | fill. 2. A run flat tire having a chafer made of a rubber composition for chafers according to claim 1, wherein the rubber component is made of natural rubber and butadiene rubber.

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