JP2006249378A - Rubber composition and pneumatic tire by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition satisfying its working property in a factory and also capable of obtaining a performance excellent in gripping property, in the case of using as a tire tread, and a pneumatic tire by using the same. <P>SOLUTION: This rubber composition is obtained by blending at least 1 kind of a catechol being solid in a room temperature and having 25-80°C primary transition temperature or secondary transition temperature for a rubber component consisting of at least 1 kind among natural rubbers and synthetic diene rubbers. As the catechol, an alklycatechol, especially p-tert-butylcatechol is suitably used. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber composition and a pneumatic tire using the rubber composition. More specifically, the rubber composition exhibits excellent grip performance and excellent factory workability, particularly when used for a tire tread. It relates to the used pneumatic tire.

  In recent years, with the improvement of automobile performance, road paving, and the development of highway networks, there is an increasing demand for pneumatic tires with high-speed mobility. The higher this characteristic, the faster and more accurately and safely it is possible to travel. In particular, grip performance represented by acceleration performance and brake performance is an important required characteristic.

  Conventionally, in order to obtain high grip performance, there has been a method of using a styrene-butadiene copolymer rubber having a high styrene content, which is a rubber having a high glass transition temperature, as a rubber composition for a tire tread. However, although this method can improve the grip performance, there is a disadvantage that the tan δ value decreases and the grip performance sharply decreases as the rubber temperature increases due to running.

  Patent Document 1 discloses a monomer such as 1,3-butadiene, styrene, or isoprene, diphenyl-2-methacryloyloxyethyl phosphate, or diphenyl-2-acryloyloxyethyl in order to improve a decrease in grip performance with an increase in temperature. A technique using a copolymer rubber obtained by copolymerization with a methacrylate compound or an acrylate compound containing a diphenyl phosphate group such as phosphate has been reported.

  In addition, by using a compound system that is highly filled with process oil and carbon black, a method of increasing the tan δ value of the rubber composition or by adding a certain resin increases the adhesion between the rubber and the road surface. A technique for improving grip performance is also known.

Further, Patent Document 2 discloses at least one organic compound having a primary or secondary transition temperature of 80 to 160 ° C. that is solid at room temperature and substantially insoluble in a rubber component in a rubber composition for a tire tread. A technique is disclosed in which high grip performance and low rotational resistance can be obtained at a normal use temperature by containing.
JP 59-187011 A Japanese Patent Laid-Open No. 9-40809

  The technique described in Patent Document 1 is not only applicable to natural rubber, but also has the disadvantage of impairing the inherent performance of polymers such as styrene-butadiene copolymer rubber and polybutadiene rubber depending on production conditions. In addition, the method of using a compound system that is highly filled with process oil and carbon black improves the grip performance, but there is a limit to high filling due to a significant decrease in fracture characteristics and wear resistance. There was a disadvantage that it was difficult to obtain grip performance.

  Although the method of adding a certain kind of resin and the technique described in Patent Document 2 can improve the grip performance, generally, the higher the grip performance, the better the adhesion with the metal mixer and metal roll existing in the manufacturing process. It tends to hinder factory workability. Therefore, a rubber composition that sufficiently satisfies both grip performance and factory workability is desired.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a rubber composition that satisfies the factory workability when used for a tire tread and that has excellent grip performance, and a pneumatic tire using the rubber composition.

  As a result of intensive studies to solve the above problems, the present inventors have solved the above problems by blending a rubber composition with an organic compound having a specific structure having a primary or secondary transition temperature of 25 ° C. to 80 ° C. The present inventors have found that this can be done and have completed the present invention.

  That is, the rubber composition of the present invention is solid at room temperature with respect to a rubber component composed of at least one of natural rubber and synthetic diene rubber, and has a primary or secondary transition temperature of 25 to 80 ° C. It is characterized in that it contains at least one catechol.

  In the rubber composition of the present invention, the catechol is preferably alkyl catechol, more preferably p-tert-butyl catechol. Further preferably, the amount of the catechol is 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the rubber component.

  The pneumatic tire of the present invention is characterized by using the rubber composition of the present invention as a tire member. Moreover, what a tire member is a tread member is preferable.

  A tire using the rubber composition of the present invention for a tread can greatly improve grip performance as compared with a conventional tire without impairing factory workability.

Hereinafter, preferred embodiments of the present invention will be specifically described.
The rubber composition of the present invention is characterized in that a specific catechol is blended with the rubber components of natural rubber and synthetic diene rubber. The rubber component includes natural rubber and synthetic diene rubber. The rubbers may be used alone or in combination. Preferably, in addition to natural rubber (NR), styrene / butadiene copolymer rubber (SBR), isoprene rubber (IR), butadiene rubber (BR), and nitrile. Synthetic diene rubbers such as rubber (acrylonitrile-butadiene copolymer) (NBR), hydrogenated nitrile rubber (H-NBR), butyl rubber (IIR) and the like can be mentioned.

  The catechol compounded in the rubber composition of the present invention is a catechol compound that is solid at room temperature and has a primary or secondary transition temperature of 25 to 80 ° C. However, one kind or a mixture of two or more kinds may be used. Although it is possible to improve the grip performance by using catechols having a primary or secondary transition temperature exceeding 80 ° C, catechols having a transition temperature of 25 to 80 ° C and a low transition temperature are used. As a result, not only grip performance but also factory workability is improved. The catechols are preferably alkyl catechols, more preferably p-tert-butyl catechol.

  It is preferable that the compounding quantity of catechol which concerns on this invention is 0.1-5.0 mass parts with respect to 100 mass parts of rubber components. If the amount of catechol is less than the above range, sufficient grip characteristics may not be obtained. On the other hand, if it exceeds the above range, factory workability may be deteriorated. In addition, when using 2 or more types of catechols in mixture, it is the total amount.

  In the rubber composition of the present invention, the reinforcing filler is not particularly limited, and one or more of carbon black, silica, alumina, aluminum hydroxide, calcium carbonate, titanium oxide, and the like are used. Carbon black can be used preferably.

  In the present invention, in addition to the rubber components, catechols, and reinforcing fillers described above, compounding agents commonly used in the rubber industry, such as softeners, anti-aging agents, coupling agents, vulcanizing agents, etc. An accelerator, a vulcanization acceleration aid, a vulcanizing agent, and the like can be blended within a range of blending amounts that are normally used, if necessary.

  The rubber composition of the present invention can be obtained by kneading using a kneader such as an open kneader such as a roll or a closed kneader such as a Banbury mixer. However, the present invention is not particularly limited to tires and can be applied to various rubber products. As a tire application, it can be used for a tire tread, an under tread, a carcass, a sidewall, a bead portion, and the like, and among them, it is preferably used as a tire tread rubber.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Examples 1-3, Comparative Example 1
The rubber composition was blended and formulated at the ratio shown in Table 1 below, and a rubber composition was obtained according to a conventional method. In addition, the numerical value in a table | surface is a mass part. As catechol according to the present invention, p-tert-butylcatechol was used. This p-tert-butylcatechol is a solid at room temperature, and has a primary transition temperature of 52 to 55 ° C and a secondary transition temperature of 285 ° C.

  Each of the obtained rubber compositions was applied to a tire tread according to a conventional method to prepare a test tire. The tire size was 225 / 40R18. The test workability of the test tire and the grip performance of the tire were evaluated by the following methods.

(1) Factory workability The adhesion of the resin compounded rubber to the metal mixer and metal roll during kneading was evaluated by the following ranking.
○ (good), ○ to △ (somewhat good), △ (normal), △ to × (somewhat bad), × (bad)
(2) Grip performance of tires A test course of one lap of 4.4 km was run, and the lap times up to the twelfth to twentieth laps of the respective examples and comparative examples were measured. The average lap time was divided by the tire time of Comparative Example 1, and a value obtained by multiplying the reciprocal by 100 was displayed as an index. A larger value indicates a higher grip performance, and a smaller value indicates a lower grip performance.
The respective evaluation results are also shown in Table 1.

  From Table 1 above, it was confirmed that the grip performance was improved as the amount of p-tert-butylcatechol increased. Moreover, although the factory workability in Example 3 where the blending amount of p-tert-butylcatechol, which is a catechol according to the present invention, is the largest among the above-mentioned examples, a slight deterioration in factory workability is seen, All examples were fully satisfactory.

Claims (6)

  At least one catechol which is solid at room temperature and has a primary transition temperature or a secondary transition temperature of 25 to 80 ° C. is blended with at least one rubber component of natural rubber and synthetic diene rubber. A rubber composition characterized by comprising:   The rubber composition according to claim 1, wherein the catechol is an alkyl catechol.   The rubber composition according to claim 2, wherein the alkyl catechol is p-tert-butyl catechol.   The rubber composition according to any one of claims 1 to 3, wherein a compounding amount of the catechols is 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the rubber component.   A pneumatic tire using the rubber composition according to any one of claims 1 to 4 as a tire member.   The pneumatic tire according to claim 5, wherein the tire member is a tread member.