JP2008179761A - Rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition excellent in thermal conductivity and also strength, elongation and the like, by increasing reinforcement of the rubber composition compounded with graphitized vapor phase-grown carbon fiber. <P>SOLUTION: The rubber composition is provided by compounding the graphitized vapor phase-grown carbon fiber into rubber components, wherein the graphitized vapor phase-grown carbon fiber is treated by solid phase reaction. The graphitized vapor phase-grown carbon fiber is preferably chemically modified by the solid phase reaction. The graphitized vapor phase-grown carbon fiber can be suitably treated by solid phase reaction using vibration equipment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rubber composition, and more particularly, to an improvement in a rubber composition formed by blending graphitized vapor-grown carbon fibers.

  Generally, the thermal conductivity of the resulting rubber composition is increased by blending the vapor-grown carbon fiber with the rubber. This makes it easy to dissipate the heat in the rubber, and it is possible to improve the durability of the rubber composition and shorten the vulcanization time. Various proposals have been made so far (see, for example, Patent Document 1).

In addition, for the purpose of improving rubber physical properties, it is also known that a graphitized vapor-grown carbon fiber obtained by graphitizing vapor-grown carbon fiber by heat treatment is blended in a rubber composition, and its degree of graphitization is high. For example, Patent Document 2 discloses that the effect of improving electrical conductivity and thermal conductivity is high. Furthermore, Patent Document 3 discloses a technique for realizing a rubber composition having low specific gravity, high strength, and reduced hysteresis loss or dynamic loss by blending fullerenes chemically modified to the rubber component. ing.
JP 2003-327753 A (Claims etc.) Japanese Patent Laid-Open No. 8-127664 (claims, etc.) Japanese Patent Laying-Open No. 2005-200641 (Claims etc.)

  As described above, blending the graphitized vapor-grown carbon fiber has the advantage of improving the thermal conductivity of the blend, but the surface of the graphitized vapor-grown carbon fiber is stabilized. Therefore, there is a problem that the polymer has little reinforcing property and the strength is lowered.

  Therefore, the object of the present invention is to solve the above problems and improve the reinforcement in a rubber composition containing graphitized vapor-grown carbon fiber, in addition to thermal conductivity, strength, extensibility, etc. The object is to provide an excellent rubber composition.

  As a result of intensive studies, the present inventor has found that a rubber composition capable of solving the above problems can be obtained by adopting the following constitution, and has completed the present invention.

That is, the rubber composition of the present invention is a rubber composition in which graphitized vapor-grown carbon fiber is blended with a rubber component.
The graphitized vapor grown carbon fiber is processed by a solid phase reaction.

  In the present invention, the graphitized vapor-grown carbon fiber is preferably chemically modified by a solid phase reaction, and preferably is chemically modified by a solid phase reaction using anthracene, ethylenediamine, or a thiol compound. Is used. The graphitized vapor grown carbon fiber can be treated by a solid phase reaction using a vibration device. Furthermore, the graphitized vapor grown carbon fiber is preferably blended in an amount of 1 to 50 parts by weight with respect to 100 parts by weight of the rubber component.

  According to the present invention, the rubber composition containing the graphitized vapor-grown carbon fiber can improve the reinforcing property, and in addition to the thermal conductivity, the strength, extensibility, etc. In addition, an excellent rubber composition can be realized.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The rubber composition of the present invention is characterized in that a graphitized vapor-grown carbon fiber is blended with a rubber component, and the graphitized vapor-grown carbon fiber is processed by a solid-phase reaction. By physically treating the surface of graphitized vapor-grown carbon fiber blended with the rubber component in advance by a solid-phase reaction, the surface can be activated and the reinforcement can be improved. As a result, heat conduction As a result, it has become possible to obtain a rubber composition excellent in strength, extensibility and the like.

  The graphitized vapor-grown carbon fiber used in the present invention has a higher degree of graphitization by heating ordinary vapor-grown carbon fiber. For example, the graphitized vapor-grown carbon fiber is 2000 to 3500 ° C., 1 It is obtained by heat-treating in ~ 3 hours. Specifically, such graphitized vapor-grown carbon fiber is readily available on the market as, for example, trade name VGCF-R manufactured by Showa Denko K.K.

Vapor-grown carbon fiber is a fine fibrous structure on the order of 10 ⁻² to 10 ⁻¹ times that of normal carbon fiber (CF) (average diameter of 5 μm or more and length of about 100 μm). In the present invention, any vapor-grown carbon fiber may be used, but the fiber diameter is preferably 0.04 to 0.4 μm, more preferably 0.05 to 0.3 μm, particularly 0.07 to 0. .3 μm is used. Further, the fiber length is not particularly limited, and those having an average fiber length of 0.5 to 50 μm, more preferably 1 to 50 μm, and particularly 1.5 to 25 μm can be used. Further, as the specific surface area, 5 to 50 m ² / g, and particularly preferably in the range of 8~30m ² / g. Such vapor-grown carbon fiber is easily available on the market, and for example, vapor-grown carbon fiber VGCF (registered trademark) manufactured by Showa Denko KK can be used.

  It is also preferable to use a vapor-grown carbon fiber having an average aspect ratio of less than 10. In the compounded rubber obtained thereby, the mechanical properties are improved without impairing the effect of improving thermal conductivity and electrical conductivity. To do. Such a low aspect ratio vapor-grown carbon fiber can be obtained, for example, by short pulverizing a long vapor-grown carbon fiber produced by a usual method. Specifically, there are a method of mechanically pulverizing using a ball mill mixer or a mortar, a method of dispersing in an aqueous or organic solvent and pulverizing by applying ultrasonic waves, etc. Vapor-grown carbon fibers having an aspect ratio of less than 10 can be obtained.

  Furthermore, the vapor growth carbon fiber may be used after being oxidized. Examples of the oxidation treatment method include chemical treatment using nitric acid, sulfuric acid, perchloric acid or a mixture of these acids, and physical treatment such as corona discharge treatment, plasma treatment, and ozone treatment. Furthermore, in addition to the oxidation treatment, vapor-grown carbon fibers treated with a coupling agent can also be used. Examples of such coupling agents include titanate-based, aluminum-based, and silane-based coupling agents, These coupling agents can be treated by a method such as dissolving in a solvent and impregnating the vapor growth carbon fiber.

  The solid-phase reaction of graphitized vapor-grown carbon fiber in the present invention can be performed using a commercially available vibration device (solid-phase reaction device) that can generate a solid-phase reaction by applying vibration. Is obtained by placing graphitized vapor-grown carbon fiber in such a vibration device together with a metal ball such as iron having a diameter of about 3 to 10 mm, and applying vibration at 100 to 2000 rpm at room temperature for 1 to 60 minutes. Do. In this case, the graphitized vapor-grown carbon fiber is chemically treated by adding a polycyclic aromatic compound such as anthracene, an amine compound such as ethylenediamine, or a thiol compound together with the graphitized vapor-grown carbon fiber to cause a solid-phase reaction. It is preferable to modify and activate the surface, thereby improving the reinforcing property and reducing the loss. Anthracene or a thiol compound is more preferable, and a thiol compound is particularly preferable. This is because the thiol group is considered to be co-crosslinked with the polymer, and a higher effect is obtained.

  The thiol compound in the present invention is not particularly limited as long as it is a polymer having a thiol group. For example, pentaerythritol tetrakis-3-mercaptopropionate (PEMP), dipentaerythritol hexa-3-mercaptopropionate (DPMP) ), Tris-[(3-mercaptopropionyloxy) -ethyl] -isocyanate (TEMPIC), trimethylolpropane tris-3-mercaptopropionate (TMMP), and the like.

  The rubber component used in the present invention is not particularly limited, and natural rubber (NR), general-purpose synthetic rubber such as emulsion polymerization styrene-butadiene rubber, solution polymerization styrene-butadiene rubber, high cis-1,4 polybutadiene rubber, low Cis-1,4 polybutadiene rubber, high cis-1,4 polyisoprene rubber, etc., diene special rubber, such as nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, olefin special rubber, such as ethylene-propylene rubber, Any of butyl rubber, halogenated butyl rubber, acrylic rubber, chlorosulfonated polyethylene, and other special rubbers such as hydrin rubber, fluorine rubber, polysulfide rubber, and urethane rubber can be used. From the balance between cost and performance, natural rubber or general-purpose synthetic rubber is preferably used.

  The amount of graphitized vapor-grown carbon fiber in the rubber composition of the present invention is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the rubber component. If the blending amount of the graphitized vapor grown carbon fiber is less than this range, sufficient thermal conductivity may not be imparted. On the other hand, if it is more than this range, the strength is lowered, which is not preferable.

  In addition to the graphitized vapor-grown carbon fiber, carbon black can be blended in the rubber compounding of the rubber composition of the present invention. As the carbon black, known ones such as those of HAF grade can be used, and the blending amount thereof can be in the range of 30 to 60 parts by weight with respect to 100 parts by weight of the rubber component. In addition, additives commonly used in the rubber industry, such as vulcanizing agents, vulcanization accelerators, anti-aging agents, process oils, reinforcing materials, softeners, etc., can be blended as appropriate. As for, a commercial item can be used conveniently.

  Examples of the vulcanizing agent include sulfur and a sulfur-containing compound, and the blending amount thereof is preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight as a sulfur content with respect to 100 parts by weight of the rubber component. . The vulcanization accelerator is not particularly limited, and examples thereof include 2-mercaptobenzothiazole (M), dibenzothiazyl disulfide (DM), N-cyclohexyl-2-benzothiazyl sulfenamide ( CZ) and the like, and guanidinium vulcanization accelerators such as diphenyl guanidine (DPG), and the use amount thereof is generally preferably 0.1 to 7 parts by weight with respect to 100 parts by weight of the rubber component. More preferably, it is 1 to 5 parts by weight. In addition, examples of process oils include paraffinic, naphthenic, and aromatic oils, and aromatic oils have improved hysteresis loss and low-temperature characteristics for applications that emphasize improvement in tensile strength and wear resistance. Naphthenic or paraffinic are used for important applications. The amount used is preferably 0 to 100 parts by weight with respect to 100 parts by weight of the rubber component, and if it exceeds 100 parts by weight, the tensile strength and low heat build-up of the vulcanized rubber tend to deteriorate.

  The rubber composition of the present invention can be obtained by mixing and kneading a rubber component, graphitized vapor-grown carbon fiber and other compounding components. The rubber composition of the present invention is preferably used after being vulcanized, and can be suitably used as, for example, a tread rubber of a tire.

Hereinafter, the present invention will be described in more detail with reference to examples.
Using a commercially available solid-phase reactor (Retstch (Germany), model number MM200), graphitized vapor-grown carbon fiber (Showa Denko Co., Ltd., trade name VGCF-R) and an iron ball were introduced. Solid phase reaction at room temperature, reaction time 30 min, 1800 rpm, solid phase reaction with 10% by weight of anthracene added, ethylenediamine added in an equimolar number with anthracene, Each of the phase-reacted materials was prepared.

  Vulcanized rubber compositions of Examples 1 to 3 and Comparative Example 1 were prepared according to the formulation shown in Table 1 below. Using a lab plast mill (manufactured by Toyo Seiki), 1 non-pro mixing (rubber + vapor-grown carbon fiber (with or without treatment) + stearic acid + anti-aging agent + zinc white) for 2 minutes, 2 pro mixing (non-pro rubber + (Vulcanization accelerator + vulcanizing agent) was performed for 1 minute, respectively, and then molded into 100 mm x 100 mm x 2 mm and vulcanized at 150 ° C for 15 minutes to obtain a vulcanized rubber.

<Tensile test>
A tensile test was performed in accordance with JIS K6301 at a room temperature of 25 ° C. and a humidity of 70 RH%, and the tensile strength and elongation at break were measured. The results are shown in Table 1 below using an index with the comparative example as 100. In any case, the larger the value, the better the result.

＊１）スチレンーブタジエンゴム（ＪＳＲ（株）製，商品名ＪＳＲ１５００）
＊２）Ｎ−（１，３−ジメチルブチル）−Ｎ’−フェニル−Ｐ−フェニレンジアミン
＊３）Ｎ−シクロヘキシル−２−ベンゾチアジル・スルフェンアミド

* 1) Styrene-butadiene rubber (trade name: JSR1500, manufactured by JSR Corporation)
* 2) N- (1,3-dimethylbutyl) -N′-phenyl-P-phenylenediamine * 3) N-cyclohexyl-2-benzothiazyl sulfenamide

  As shown in Table 1 above, in the rubber compositions of Examples 1 to 3 in which graphitized vapor-grown carbon fibers surface-treated by a solid-phase reaction are blended, untreated graphitized vapor-grown carbon It was confirmed that both the tensile strength and the elongation at break were improved as compared with the rubber composition of Comparative Example 1 formed by blending fibers.

  According to the composition shown in Table 2 below, vulcanized rubber compositions of Examples 4 to 6 and Comparative Example 2 were prepared in the same manner as in Examples 1 to 3 and Comparative Example 1.

<Loss characteristic test>
For each vulcanized rubber composition, tan δ at 50 ° C. was measured under a dynamic strain of 2% using a viscoelasticity measuring tester manufactured by Rheometrics. The results are shown in Table 2 below using an index with the comparative example as 100. In any case, the smaller the numerical value, the better the result.

＊４）カーボンブラック（旭カーボン社製、商品名旭♯７０）
＊５）ペンタエリスリトール テトラキス−３−メルカプトプロピオネート（堺化学工業（株）製、商品名ＰＥＭＰ）

* 4) Carbon black (Asahi Carbon Co., Ltd., trade name Asahi # 70)
* 5) Pentaerythritol tetrakis-3-mercaptopropionate (manufactured by Sakai Chemical Industry Co., Ltd., trade name PEMP)

  As shown in Table 2 above, in the rubber compositions of Examples 4 to 6 in which the graphitized vapor-grown carbon fibers surface-treated by solid-phase reaction were blended, untreated graphitized vapor-grown carbon Compared to the rubber composition of Comparative Example 2 in which fibers were blended, both had improved tensile strength, and in Examples 5 and 6 to which anthracene or PMP was added, the elongation at break and loss characteristics were improved. It was confirmed that

Claims (5)

In the rubber composition in which graphitized vapor-grown carbon fiber is blended with the rubber component,
A rubber composition obtained by treating the graphitized vapor-grown carbon fiber by a solid-phase reaction.   The rubber composition according to claim 1, wherein the graphitized vapor-grown carbon fiber is chemically modified by a solid-phase reaction.   The rubber composition according to claim 1 or 2, wherein the graphitized vapor-grown carbon fiber is treated by a solid-phase reaction using a vibration device.   The rubber composition according to claim 2 or 3, wherein the graphitized vapor-grown carbon fiber is chemically modified by a solid-phase reaction using anthracene, ethylenediamine, or a thiol compound.   The rubber composition according to any one of claims 1 to 4, wherein the graphitized vapor-grown carbon fiber is blended in an amount of 1 to 50 parts by weight with respect to 100 parts by weight of the rubber component.