JP2011236533A - Carbon fiber for rubber reinforcement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon fiber for rubber reinforcement, having excellent adhesion between the carbon fiber and rubber without using an epoxy compound or the like.SOLUTION: A carbon fiber for rubber reinforcement comprises a surface to which an amine derivative having a hydroxyl group, block polyisocyanate, and rubber latex are attached. It is preferred that the hydroxyl group of the amine derivative be located at an end of the aliphatic hydrocarbon, that the amine derivative be prepared by alkylene oxide addition to amine, and that the amine derivative be in direct contact with the carbon fiber surface. Preferably the outermost surface material is a resorcin-formalin-latex adhesive.

Description

  The present invention relates to a carbon fiber for reinforcing rubber, and more particularly to a non-epoxy type rubber fiber for reinforcing rubber that is suitably used for rubber / fiber composites such as tires, hoses, and belts.

  Carbon fiber has excellent properties such as high elastic modulus, high strength, dimensional stability, heat resistance and chemical resistance, and is expected to be used as a rubber reinforcing fiber for tires, hoses, belts, etc. Has been. However, the surface of carbon fibers is often relatively inactive, and as such, the adhesiveness with a matrix such as rubber or resin is insufficient, and the characteristics of carbon fibers cannot be fully exhibited.

  For this reason, a so-called two-bath adhesion treatment method in which the fiber surface is treated with a chemical such as an epoxy compound and a block polyisocyanate compound and further treated with a resorcin / formalin / rubber latex (RFL) adhesive has been proposed and put into practical use. (Patent Document 1, etc.). However, the development of alternative technologies has been demanded from the viewpoint of the environment and the like for epoxy compounds that have been frequently used.

JP 2006-214043 A

  An object of the present invention is to provide a carbon fiber for reinforcing rubber having excellent adhesion without using an epoxy compound or the like in bonding carbon fiber and rubber.

The carbon fiber for reinforcing rubber of the present invention is characterized in that an amine derivative having a hydroxyl group, a block polyisocyanate, and a rubber latex are attached to the surface of the carbon fiber.
Further, the hydroxyl group of the amine derivative is located at the end of the aliphatic hydrocarbon, the amine derivative is an alkylene oxide adduct of an amine, and the amine derivative is in direct contact with the carbon fiber surface. It is preferable. The outermost surface is preferably a resorcin / formalin / latex adhesive.

  ADVANTAGE OF THE INVENTION According to this invention, the carbon fiber for rubber reinforcement which has the outstanding adhesiveness without using an epoxy compound etc. in the adhesion | attachment of carbon fiber and rubber | gum is provided.

  The present invention is a carbon fiber for reinforcing rubber, wherein an amine derivative having a hydroxyl group, a blocked polyisocyanate or a reaction product thereof, and a rubber latex are attached to the surface of the carbon fiber.

  As the carbon fiber used here, a conventionally known carbon fiber can be used. In particular, a PAN-based carbon fiber excellent in strength is preferable. Moreover, it is preferable that it is a fiber bundle for rubber reinforcement, and it is preferable that the total fineness is 2000 dtex or more, Furthermore, it is the range of 5000-1 million dtex. The number of filaments is preferably 500 filaments or more, particularly in the range of 10,000 to 500,000 filaments. The carbon fiber for reinforcing rubber of the present invention includes various fiber aggregate forms such as yarn, cord, nonwoven fabric, woven or knitted fabric.

  The carbon fiber for reinforcing rubber of the present invention is one in which an amine derivative is attached to the surface of such a carbon fiber, and this amine derivative must have a hydroxyl group. The amine derivative is an amine derivative containing at least one of a primary amine, a secondary amine, and a tertiary amine as a nitrogen moiety. The hydroxyl group is preferably a hydroxyl group at the end of the aliphatic hydrocarbon. In the case of a phenolic hydroxyl group (OH) compound rather than an aliphatic compound, there is a tendency that it is difficult to form an effective cross-linked structure due to the difference in reactivity. Further, the number of hydroxyl groups is preferably 3 to 12, particularly preferably 4 or 5. When the number of hydroxyl groups is too large, it tends to be difficult to form a uniform crosslinked structure, and when it is too small, it is difficult to obtain an effective crosslinking density.

  Furthermore, it is also preferable that all nitrogen sites are tertiary amines substituted with hydrocarbon groups or the like. Such nitrogen sites are preferably 1 to 10, particularly preferably 2 to 3. By increasing the nitrogen site of the amine derivative, the reactivity with blocked isocyanate which is another essential component can be enhanced.

  Further, the amine derivative is preferably an amine alkylene oxide adduct, and more preferably the end of the alkylene oxide is a hydroxyl group. Examples of the alkylene oxide include polyethylene oxide and polypropylene oxide, and polyethylene oxide is most preferable. Moreover, it is preferable that the addition mole number of alkylene oxide is 4-8.

  In the rubber fiber for reinforcing rubber of the present invention, such an amine derivative having a hydroxyl group reacts with the block polyisocyanate by a subsequent heat treatment to form a higher-order cross-linked structure, thereby strengthening the aggregate structure as an adhesive on the fiber surface. There is a work to make.

  This amine derivative is preferably in the range of 0.1 to 10 parts by weight, more preferably in the range of 1 to 5 parts by weight, with respect to 100 parts by weight of the block polyisocyanate compound described below. When the addition amount is within the above range, an effective crosslinking density can be easily obtained, and the adhesive force tends to be further improved.

  The block polyisocyanate in the present invention is an addition reaction product of a polyisocyanate compound and a blocking agent, and the block component is liberated by heating to produce an active polyisocyanate compound. In this case, the number of terminal isocyanate groups is preferably 3 or more. As the polyisocyanate compound, polyisocyanate such as tolylene diisocyanate, metaphenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, triphenylmethane triisocyanate, or one or more of these polyisocyanates and active hydrogen atoms A terminal isocyanate group-containing polyisocyanate obtained by reacting a compound having an isocyanate group (—NCO) and a hydroxyl group (—OH) in a molar ratio exceeding 1 is preferable because it exhibits excellent performance. Examples of the blocking agent include phenols such as phenol, thiophenol, cresol and resorcinol, aromatic secondary amines such as diphenylamine and xylidine, phthalimides, lactams such as caprolactam and valerolactam, acetoxime, methyl ethyl keto Examples include oximes such as oxime and cyclohexanone oxime, and acidic sodium sulfite.

  The content of the block polyisocyanate compound is preferably in the range of 10 to 60% by weight. When the content is too small, the chemical affinity for the fiber surface is insufficient, and the adhesive strength tends to be insufficient. On the other hand, if the amount is too large, the adhesive layer becomes hard and the cord strength does not develop, and there is a tendency that problems such as impregnation dipping and removal of the adhesive layer during the processing process occur.

  The rubber latex adhering to the fiber surface in the present invention includes, for example, natural rubber latex, styrene / butadiene copolymer latex, vinylpyridine / styrene / butadiene terpolymer latex (hereinafter referred to as Vp latex), nitrile rubber latex, There are chlorobrene rubber latex, ethylene / propylene / diene monomer latex and the like, and these can be used alone or in combination. Especially, what uses Vp latex individually or in combination with another thing is preferable. In the case of use in combination, a product with particularly excellent performance is obtained when the Vp latex is used in an amount of 1/3 or more of the total latex weight.

  Furthermore, in this invention, it is also preferable that the polymer which copolymerized the organic compound which has a vinyl halide group has adhered to the fiber. As a polymer having such a vinyl halide group that can be preferably used in the present invention, a film forming temperature of 200 ° C. or lower, more preferably 180 ° C. or lower is preferable. Such a polymer preferably used in the present invention is vinyl chloride alone or a compound obtained by various copolymerizations, such as vinyl chloride and vinyl acetate, vinyl chloride and vinylidene chloride, vinyl chloride and acrylonitrile, A copolymer of vinyl chloride and vinyl acetate, a terpolymer of vinyl chloride, vinyl acetate, and maleic anhydride, or a mixture thereof can be given.

  The rubber reinforcing carbon fiber of the present invention has the above components attached to the fiber surface. As the attached state, it is particularly preferable that the amine derivative is located on the fiber surface. As such, when the amine derivative is in direct contact with the carbon fiber, the adhesion of the carbon fiber surface can be further improved.

  In order to achieve such an adhesion state, the carbon fiber can be obtained by treating with a pretreatment agent containing an amine derivative having a hydroxyl group in advance and then treating with an adhesive containing block polyisocyanate and rubber latex. . The pretreatment agent preferably contains block polyisocyanate and / or rubber latex. The adhesive is preferably mainly composed of a so-called resorcin / formalin / rubber latex adhesive (RFL adhesive). In addition, before attaching the pretreatment agent, it is also possible to use the carbon fiber after treating various impregnation treatment agents in order to improve the fatigue resistance of the carbon fiber or the adhesion between the carbon fiber and the pretreatment agent. it can.

  As a blending of the RFL adhesive which is this preferable adhesive component, a molar ratio of resorcin to formaldehyde is preferably in the range of 1: 0.1 to 1: 8, more preferably 1: 1 to 1: 4. It is preferable that it is the range of these. If the amount of formaldehyde added is too small, the crosslink density of the condensate of resorcin / formalin will be reduced and the molecular weight will be lowered.Therefore, the adhesiveness tends to be lowered due to the reduced cohesive force of the adhesive layer. If the amount is too large, the resorcin / formalin condensate becomes hard due to an increase in cross-linking density, and the compatibility between the adhesive and the rubber tends to be impaired during co-vulcanization with the adherend rubber, and the adhesiveness tends to decrease. The blending ratio of resorcin / formalin and rubber latex in the RFL adhesive is preferably a solid content ratio of resorcin / formalin: rubber latex in the range of 1: 1 to 1:15. If the ratio of the rubber latex is too small, the treated fiber becomes hard and the fatigue resistance tends to be lowered. Moreover, co-vulcanization with the latex in the pretreatment agent and the rubber that is the adherend may be insufficient, which may reduce the adhesiveness. Conversely, if the ratio is too large, sufficient strength as an adhesive film is obtained. Therefore, there is a possibility that satisfactory adhesive strength and rubber adhesion rate cannot be obtained.

  Moreover, in order to obtain the carbon fiber for rubber reinforcement of this invention, when performing a two-step process of a pretreatment agent and an adhesive agent, the total solid content concentration of the pretreatment agent is 1 to 30% by weight, preferably 1.5. It is preferably in the range of ˜20% by weight, more preferably in the range of 2 to 15% by weight. If the total solid concentration of the treatment agent is too low, the surface tension of the agent increases and the uniform adhesion to the fiber surface decreases, and the adhesion decreases due to the decrease in the solid adhesion amount. If the concentration of the agent is too high, not only is it disadvantageous in terms of production cost, but the amount of solid content is too large, so it becomes hard and fatigue resistance tends to decrease, which is not preferable. Further, the dispersant used when the pretreatment composition is used as an aqueous dispersion, that is, an appropriate amount of the surfactant is 15% by weight or less based on the total solid content of the pretreatment agent, preferably It is preferably used at 10% by weight or less. When there is too much quantity of surfactant, it exists in the tendency for adhesiveness to be inhibited.

  The amount of solid content of the pretreatment agent to the carbon fiber when performing the two-stage treatment is preferably used in the range of 0.1 to 10% by weight, more preferably in the range of 0.3 to 7% by weight. Is preferably adhered in the range of 0.5 to 5% by weight. In order to control the solid content of the pretreatment agent on the fiber, means such as squeezing by a pressure roller, scraping by a scrubber, blowing by air blowing, suction, hitting by a beater, etc. may be employed. Moreover, you may make it adhere several times in order to raise the adhesion amount or to ensure uniformity.

  As a preferable two-step treatment method, a treatment with a pretreatment agent containing an amine derivative, a blocked polyisocyanate, or a rubber latex, followed by treatment with an adhesive containing a blocked polyisocyanate and a rubber latex can be given. Furthermore, the adhesive preferably contains a block polyisocyanate, a rubber latex, and an isocyanate-reactive thermoplastic elastomer, and most preferably an RFL adhesive.

  The isocyanate-reactive thermoplastic elastomer preferably used here may be any one having a group that reacts with isocyanate. Preferably, the hard segment of the elastomer is any one group of phenolic hydroxyl group, hydroxyl group, and amino group. Those having the following are preferred. The soft segment preferably has a component such as butadiene and isoprene that can be co-vulcanized with a rubber component. In particular, the thermoplastic elastomer is preferably a copolymer of polybutadiene and polyurethane. The ratio of the thermoplastic elastomer to the rubber latex is preferably 2: 1 to 1: 2, and the ratio of the thermoplastic elastomer to the block polyisocyanate is preferably 100: 15 to 100: 100. The above-mentioned thing can be used as various agents used here.

  The blending amount of the block polyisocyanate compound is not constant depending on the type and the blending of the adherent rubber. For example, when the above-mentioned adhesive is used, it is 5 to 40% by weight, preferably 10 to 30% by weight based on the solid content. % Is appropriate. Here, when there is too little addition amount of block polyisocyanate, the cohesive energy of an adhesive agent is not enough and an adhesive interlayer fracture | rupture is caused. On the other hand, when the amount is too large, the adhesive layer becomes hard, the dip cord strength cannot be expressed, and the fatigue property is decreased, which is not suitable for practical use.

  Such an adhesive preferably has a total solid content in the range of 1 to 30% by weight, more preferably 2 to 25% by weight, and particularly 5 to 20% by weight. To use. If the concentration of the adhesive is too low, the adhesiveness decreases due to a decrease in the amount of adhesion, and conversely, if the concentration is too high, the amount of solid content increases so that the fiber becomes hard and fatigue resistance tends to decrease. .

  The adhesive can be adhered to the fiber by contact with a roller, application by spraying from a nozzle, immersion in a solution, or the like. Moreover, it is preferable that the solid content adhesion amount with respect to the fiber of an adhesive agent is the range of 0.1-10 weight%, Furthermore, the range of 0.2-7 weight%, Most preferably, 0.5-6 weight% It is good to adhere in the range of%. In order to control the solid content adhesion amount to the fiber, similarly to the pretreatment agent, it can be carried out by means of squeezing with a pressure roller, scraping with a scrubber, etc., blowing off with air blowing, suction, and beater.

  And the carbon fiber for rubber reinforcement of the present invention obtained by the manufacturing method as described above has high rubber adhesion, and fiber reinforced rubber structures such as tires, belts and hoses using this fiber have strength and durability. Product with excellent properties.

  The present invention will be further described in the following examples. Moreover, the cord peeling adhesive force was measured by the following method.

(1) Cord peeling adhesive strength This indicates the adhesive strength between the treated cord and rubber. 16 cords are buried near the surface layer of a carcass blended unvulcanized rubber sheet mainly composed of natural rubber, at a temperature of 150 ° C. for 30 minutes, a pressing pressure of 50 kg / cm ² (initial value), or 180 ° C. It was vulcanized at a pressing pressure (heat resistance value) of 50 kg / cm ² for 40 minutes at a temperature, and then required to peel 16 cords at a rate of 200 mm / min in the direction of 90 degrees with respect to the rubber sheet surface. The force is indicated by N / 16 lines.

[Example 1]
Solid components of trifunctional block polyisocyanate, ethylenediamineethylene oxide 4 mol adduct (amine derivative having a hydroxyl group), Vp latex, and vinyl chloride latex are mixed at a ratio of 100: 1.5: 50: 50 to obtain a total solid component concentration. Was 10%, and a treatment liquid (1) for a pretreatment agent was obtained.
An initial condensate having a resorcin / formalin (R / F) molar ratio of 1 / 0.6 and a solid content concentration of 65% by weight is dissolved under alkaline conditions to obtain a 9% by weight aqueous solution. 109 parts by weight of this aqueous solution is added to 180 parts by weight of Vp latex, 40% aqueous emulsion. To this solution, 23 parts by weight of formalin, 5 parts by weight and 33% by weight of methyl ethyl ketoxime blocked phenylmetasidiisocyanate dispersion were added, and a blended liquid having a solid content concentration of 18% by weight was obtained by aging for 48 hours. A treatment liquid (2) was obtained.

Carbon fiber bundle Carbon fiber bundle (fineness: 8000 dtex) “HTA-12K” (manufactured by Toho Tenax Co., Ltd.) Number of filaments: 12,000, single fiber diameter: 7.0 μm, tensile strength: 3920 MPa, tensile elastic modulus: 235 GPa, elongation: Using 1.7%, an untreated carbon fiber cord subjected to twisting of 60 T / cm was obtained.
This carbon fiber cord was immersed in the treatment liquid (1) using a contributor treatment machine (CA Ritzler Co., Ltd., tire cord treatment machine), then dried at a temperature of 130 ° C. for 3 minutes, Heat treatment is performed at a temperature of 200 ° C. for 1 minute, followed by dipping in the treatment liquid (2), followed by drying at a temperature of 130 ° C. for 3 minutes, and subsequently heat treatment at a temperature of 200 ° C. for 1 minute. It was. The resulting tire cord had 1.3% by weight of the pretreatment agent and 2.1% by weight of the posttreatment agent as the solid content of the treatment agent. The obtained treated cord was embedded in an unvulcanized rubber containing carcass containing natural rubber as a main component, vulcanized at a temperature of 150 ° C. for 30 minutes, and at a temperature of 180 ° C. for 60 minutes, and evaluated by the above method. The results are shown in Table 1.

[Example 2]
Instead of the ethylenediamine ethylene oxide 4 mole adduct of the treatment liquid (1), a treatment liquid (3) using triethanolamine was prepared and used as a pretreatment agent. The same treatment as in Example 1 was performed except that the treatment liquid (3) was used instead of the treatment liquid (1), and the results are also shown in Table 1.

[Example 3]
In place of the trifunctional block polyisocyanate in the treatment liquid (1), a tetrafunctional block polyisocyanate is used, and a treatment liquid (4) using only Vp latex without using vinyl chloride latex is prepared to prepare a pretreatment agent and did. The same treatment as in Example 1 was performed except that the treatment liquid (4) was used instead of the treatment liquid (1), and the results are also shown in Table 1.

[Example 4]
As a post-treatment agent, thermoplastic elastomer (Daiichi Kogyo Seiyaku Co., Ltd., F2008D), block polyisocyanate (manufactured by Meisei Chemical Industry Co., Ltd., DM6400), Vp latex, which is a copolymer of polybutadiene and polyurethane, in a solid component ratio of 50:15 : 50 was mixed to prepare a treatment liquid (5) having a total solid component concentration of 20%. The same treatment as in Example 3 was performed except that the treatment liquid (5) was used instead of the treatment liquid (2), and the results are also shown in Table 1.

[Example 5]
Before twisting the carbon fiber, it was treated with a styrene treatment agent (maleic acid-modified styrene-ethylene-butylene-styrene copolymer resin: β-pinene resin = 5: 5 aqueous dispersion), dried, and then treated with 60T. A cord subjected to twisting of / cm was obtained. Then, the process similar to Example 4 was performed and the result was combined with Table 1 and shown.

[Comparative Example 1]
Instead of the ethylenediamine ethylene oxide 4 mol adduct of the treatment liquid (1), a treatment liquid (6) using pentaerythritol was prepared and used as a pretreatment agent. The same treatment as in Example 1 was performed except that the treatment liquid (6) was used instead of the treatment liquid (1), and the results are also shown in Table 1.

Claims (5)

  A carbon fiber for reinforcing rubber, wherein an amine derivative having a hydroxyl group, a block polyisocyanate, and a rubber latex are attached to the surface of the carbon fiber.   The carbon fiber for rubber reinforcement according to claim 1, wherein the hydroxyl group of the amine derivative is located at the end of the aliphatic hydrocarbon.   The rubber fiber for reinforcing rubber according to claim 1 or 2, wherein the amine derivative is an alkylene oxide adduct of an amine.   The carbon fiber for rubber reinforcement according to any one of claims 1 to 3, wherein the amine derivative is in direct contact with the surface of the carbon fiber.   The carbon fiber for rubber reinforcement according to any one of claims 1 to 4, wherein the outermost surface is a resorcin / formalin / latex adhesive.