JP4213026B2 - Method for producing rubber reinforcing fiber - Google Patents

Description

  The present invention relates to a method for producing a rubber reinforcing fiber, and more particularly to a method for producing a synthetic fiber for rubber reinforcement suitably used for rubber / fiber composites such as tires, hoses, and belts.

  Synthetic fibers have excellent physical properties such as high strength and high Young's modulus, and are widely used as rubber reinforcing fibers for applications such as tires, hoses, and belts by utilizing these properties. However, these synthetic fibers often have a relatively inert surface, and as they are, their adhesion to a matrix such as rubber or resin is insufficient, and the physical properties of the synthetic fibers are not fully exhibited. Can not.

  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 resorcin / formalin / rubber latex (RFL) has been proposed and put into practical use ( Patent Document 1, Patent Document 2, etc.). However, there is a growing concern about the environmental impact of epoxy compounds that have been used frequently.

JP-A-54-73994 JP 2001-64840 A

  An object of the present invention is to provide an excellent method for treating a fiber for reinforcing rubber without using an epoxy compound in bonding a synthetic fiber and rubber.

  The method for producing a rubber reinforcing fiber of the present invention comprises treating a synthetic fiber with a pretreatment agent containing an amine derivative having a hydroxyl group, a block polyisocyanate, and a rubber latex, and then a posttreatment agent containing the block polyisocyanate and the rubber latex. It is characterized by processing.

  Further, all the nitrogen sites constituting the amine derivative are tertiary amines, the amine derivative is an amine alkylene oxide adduct, and the molar ratio of nitrogen and hydroxyl group constituting the amine derivative is 1: 2. It is preferably ˜1: 3.

  ADVANTAGE OF THE INVENTION According to this invention, the processing method of the fiber for rubber reinforcement which has high rubber adhesiveness is provided.

  The synthetic fiber used in the method for producing a rubber reinforcing fiber of the present invention includes polyester fiber, polyamide fiber, aromatic polyamide fiber and the like, and is particularly effective for polyester fiber or aromatic polyamide fiber. The polyester fiber is particularly preferably a fiber made of polyester having terephthalic acid or naphthalenedicarboxylic acid as the main acid component and ethylene glycol, 1,3-propanediol or tetramethylene glycol as the main glycol component. . As the aromatic polyamide fiber, polyparaaminobenzamide, polyparaphenylene terephthalamide, polyparaaminobenzhydrazide terephthalamide, polyterephthalic acid hydrazide, polymetaphenylene isophthalamide, or a so-called aramid fiber made of a copolymer thereof is used. It is preferable to be used effectively for para-aramid fibers having particularly high strength. There are no restrictions on the denier, filament number, cross-sectional shape, and the like of these synthetic fibers, and various fiber aggregate forms such as yarns, cords, nonwoven fabrics, and woven and knitted fabrics are included.

  In the treatment method of the present invention, it is essential to first treat the synthetic fiber as described above with a pretreatment agent containing an amine derivative having a hydroxyl group, a block polyisocyanate, and a rubber latex.

  The amine derivative having a hydroxyl group used in the present invention is an amine derivative having at least one of a primary amine, a secondary amine and a tertiary amine as a nitrogen moiety and having a hydroxyl group. Furthermore, it is preferable that all nitrogen sites are tertiary amines in which hydrogen atoms are substituted with hydrocarbon groups or the like. As a nitrogen site | part, it is preferable that it is 1-10 pieces, Preferably it is 2-3 pieces. Moreover, it is preferable to have 3-12, 4 or 5 as a hydroxyl group, and it is preferable that it is a hydroxyl group of the terminal of an aliphatic hydrocarbon. A phenolic OH compound rather than an aliphatic compound tends to hardly form an effective cross-linked structure due to a difference in reactivity.

  By increasing the nitrogen site of the amine derivative, the reactivity with the blocked isocyanate can be enhanced. Conversely, by reducing the number of nitrogen sites, it is possible to improve the stability in water of emulsions and dispersions such as latex that are used simultaneously as components of the pretreatment agent, making it difficult to cause gelation or precipitation. . If the number of hydroxyl groups is too large, it tends to be difficult to form a uniform crosslinked structure. If the number is too small, it tends to be difficult to obtain an effective crosslinking density, and the water solubility of the amine derivative is low. Since it is insufficient, the stability of the agent tends to decrease.

  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, but polyethylene oxide is most preferable in order to increase water solubility. Moreover, it is preferable that the addition mole number of alkylene oxide is 4-8.

  Such an amine derivative having a hydroxyl group reacts with the block polyisocyanate by heat treatment to form a higher-order cross-linked structure, and has a function of strengthening the aggregated structure of the adhesive.

  The amine derivative is preferably 0.1 parts by weight or more and 10 parts by weight or less, more preferably 1 part by weight or more and 5 parts by weight or less 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.

  Further, the block polyisocyanate compound used in the present invention is an addition reaction product of a polyisocyanate compound and a blocking agent, and the block component is released 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, lactams such as phthalimides, caprolactam and valerolactam, acetoxime, methyl ethyl keto Examples include oximes such as oxime and cyclohexanone oxime, and acidic sodium sulfite.

  As a content rate in all the active ingredients of a block polyisocyanate compound, it is preferable that it is 10 to 60 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.

  Examples of the rubber latex used in the present invention include natural rubber latex, styrene / butadiene copolymer latex, vinylpyridine / styrene / butadiene terpolymer latex (hereinafter referred to as Vp latex), nitrile rubber latex, and 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, it is also preferable to add a polymer obtained by copolymerizing an organic compound having a vinyl halide group as the pretreatment agent of the present invention. The polymer having such a vinyl halide group that can be preferably used in the present invention has a film forming temperature of 200 ° C. or lower, more preferably 180 ° C. or lower. When the film forming temperature exceeds 200 ° C., it is difficult to form a uniform film under the bonding treatment conditions. Such a polymer used in the present invention is a compound of vinyl chloride alone or variously copolymerized, such as vinyl chloride and vinyl acetate, vinyl chloride and vinylidene chloride, vinyl chloride and acrylonitrile, chloride. Mention may be made of a copolymer of vinyl and vinyl acetate, a terpolymer of vinyl chloride, vinyl acetate and maleic anhydride, or a mixture thereof.

  Such a polymer having a vinyl halide group is usually used as an aqueous dispersion, an emulsion or a solution. In order to obtain such an emulsified liquid or dispersion, for example, the thermoplastic resin is used as it is or after being dissolved in a small amount of a solvent as necessary, and then a known emulsifier such as sodium alkylbenzene sulfonate, dioctyl What is necessary is just to emulsify or disperse | distribute using a sulfosuccinate sodium salt, nonylphenol ethylene oxide adduct, etc. When adding a polymer having a vinyl halide group, if the amount is too small, the adhesive performance tends to decrease remarkably when the adhesion amount of the adhesive is reduced. , Adhesion and fatigue tend to decrease.

  The total solid concentration of the pretreatment agent containing such an amine derivative having a hydroxyl group, block polyisocyanate, and rubber latex is 1 to 30% by weight, preferably 1.5 to 20% by weight, and more preferably 2 to 15%. It is preferably in the range of% by weight. When the total solid content concentration is too low, the adhesive surface tension increases, the uniform adhesion to the fiber surface decreases, and the adhesion decreases due to the decrease in the solid content, while the treatment agent If the concentration is too high, it is not only disadvantageous in terms of production cost, but it is not preferable because the solid content adheres too much and becomes hard and fatigue resistance tends to decrease. Further, an appropriate amount of the dispersant when using the pretreatment composition 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 What is used at 10% by weight or less is preferable. If the amount of the surfactant is too large, the adhesiveness tends to be slightly lowered.

  The solid content of the pretreatment agent to the fiber 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, most preferably 0.5 to 5% by weight. It is preferable to make it adhere in the range of%. In order to control the amount of solid content attached to 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.

  The present invention is a method for treating a rubber reinforcing fiber, which is treated with a pretreatment agent containing such an amine derivative, block polyisocyanate and rubber latex, and then treated with a posttreatment agent containing block polyisocyanate and rubber latex. Furthermore, it is most preferable that the post-treatment agent includes a block polyisocyanate, a rubber latex, and an isocyanate-reactive thermoplastic elastomer.

  The isocyanate-reactive thermoplastic elastomer preferably used in the present invention is not particularly limited as long as it has a group that reacts with isocyanate. Preferably, any one of a phenolic hydroxyl group, a hydroxyl group, and an amino group is added to the hard segment of the elastomer. Those having a group 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 post-treatment agent is preferably a resorcin / formalin / rubber latex adhesive (RFL adhesive), which is a two-bath method which is an RFL adhesive as a main component and a treatment containing block polyisocyanate. As the block polyisocyanate and rubber latex used here, the above-mentioned materials used in the pretreatment agent can be used.

  The resorcin / formalin / rubber latex (RFL) preferably used in the post-treatment agent has a resorcin / formaldehyde molar ratio in the range of 1: 0.1 to 1: 8, more preferably 1: The range is preferably 0.5 to 1: 5, more preferably 1: 1 to 1: 4. If the amount of the formaldehyde added is too small, the crosslink density of the condensate of resorcin / formalin is reduced and the molecular weight is lowered. If too much formaldehyde is added, the resorcin / formalin condensate becomes hard due to an increase in crosslink density, and the compatibility between the RFL and the rubber is inhibited during co-vulcanization with the adherend rubber, resulting in a decrease in adhesion and after treatment. The shrinkage of the adhesive layer becomes remarkable, and the adhesive force due to interface peeling due to stress concentration at the interface tends to decrease. The blending ratio of resorcin / formalin and rubber latex in the RFL adhesive varies depending on the addition ratio of the block polyisocyanate, but resorcin / formalin: rubber latex (RFL) is 1: 1 to 1: Those in the range of 15 are preferable, and those in the range of 1: 3 to 1:12 are particularly preferably used. When the ratio of the rubber latex is too small, the treated fiber becomes hard and the fatigue resistance tends to be lowered. In addition, co-vulcanization with the latex in the pretreatment agent and the rubber that is the adherend becomes insufficient, and there is a possibility that the adhesiveness may be lowered. Conversely, if the ratio of the rubber latex is too large, Since sufficient strength cannot be obtained, there is a possibility that satisfactory adhesive force and rubber adhesion rate may not be obtained.

  The blending amount of the block polyisocyanate compound is not constant depending on the type and blending of the adherent rubber. For example, when the above-mentioned post-treatment agent is used, it is 5 to 40% by weight, preferably 10 to 30% based on the solid content. Weight percent is appropriate. Here, when the addition amount of the block polyisocyanate is less than the predetermined value, the cohesive energy of the adhesive is not sufficient, and adhesive interlayer breakage occurs. On the other hand, when the value exceeds the predetermined value, the adhesive layer becomes hard and the dip cord strength cannot be expressed, and a decrease in fatigue is seen, which is not suitable for practical use.

  As such a post-treatment agent, one having a total solid concentration in the range of 1 to 30% by weight is preferably used, more preferably 2 to 25% by weight, and particularly 5 to 20% by weight. Use it like this. If the concentration of the post-treatment agent is too low, the amount of adhesion of the adhesive will be reduced, and the adhesiveness will be reduced. Conversely, if the concentration of the post-treatment agent is too high, the amount of solid content will be too high and the fibers will become hard. Fatigue resistance tends to decrease.

  The post-treatment agent can be attached to the fiber by contact with a roller, application by spraying from a nozzle, immersion in a solution, or the like. The solid content of the post-treatment agent on the fibers is preferably in the range of 0.1 to 10% by weight, more preferably in the range of 0.2 to 7% by weight, most preferably 0.5 to What adheres in the range of 6 weight% is good. 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.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the cord peeling adhesive force in an Example was performed with the following measuring method.

(1) Cord peeling adhesive strength This shows the adhesive strength between the treated cord and rubber. 7 cords are buried near the surface layer of the uncured rubber sheet containing carcass containing natural rubber as a main component, and at a temperature of 150 ° C. for 30 minutes, a pressing pressure of 50 kg / cm ² (initial value), or 80 ° C. Vulcanize at a pressing pressure (heat resistance) of 50 kg / cm ^{2 at} a temperature for 40 minutes, and then peel off the three cords at a rate of 200 mm / min in the direction of 90 degrees with respect to the rubber sheet surface, leaving the cords at both ends. The force required to do this is indicated by N / 3.

[Example 1]
The solid components of trifunctional block polyisocyanate (NBP211 made by Meisei Chemical Industry), ethylenediamineethylene oxide 4 mol adduct (amine derivative), Vp latex, vinyl chloride latex (Vinyl Blanc 609 made by Nissin Chemical Industry) are 100: 1.5: The mixture was mixed at 50:50, the 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 concentration of 65% by weight is dissolved under alkaline conditions to give 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 liquid, 23 parts by weight of formalin, 5 parts by weight, 33% by weight of methyl ethyl ketoxime blocked phenylmetasidiisocyanate dispersion was added, and a blended liquid having a solid content concentration of 18% by weight was obtained after aging for 48 hours. Treatment liquid for agent (2) was obtained.

  On the other hand, a multifilament yarn of 1670 dtex / 384 filament made of polyethylene terephthalate having an intrinsic viscosity of 0.95 is used, and the multifilament yarn is subjected to a lower twist at 40 T / 10 cm. A cord of 3340 dtex / 768 filament was obtained by twisting.

The cord was immersed in the treatment liquid (1) using a contributor processing machine (tire code processing machine manufactured by CA Ritzler Co., Ltd.), then dried at a temperature of 130 ° C. for 2 minutes, and subsequently 240 ° C. Then, after being immersed in the treatment liquid (2), it was dried at a temperature of 170 ° C. for 2 minutes, followed by a heat treatment at a temperature of 240 ° C. for 1 minute. The resulting tire cord had 1.0% by weight of the pretreatment agent and 1.7% 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 mol 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]
Instead of the trifunctional block polyisocyanate in the treatment liquid (1), a treatment liquid (4) using a tetrafunctional block polyisocyanate (NBP873 manufactured by Meisei Chemical Industry) was prepared and used as a pretreatment agent. 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 Co., Ltd., DM6011), 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 1 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.

[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.

  Thus, the fiber for rubber reinforcement obtained by the treatment method of the present invention has high rubber adhesion, and fiber reinforced rubber structures such as tires, belts and hoses using this fiber are excellent in strength and durability. Become a product.

Claims (7)

  A synthetic fiber is treated with a pretreatment agent containing an amine derivative having a hydroxyl group, a block polyisocyanate, and a rubber latex, and then treated with a posttreatment agent containing a block polyisocyanate and a rubber latex. Manufacturing method.   The method for producing a rubber-reinforcing fiber according to claim 1, wherein all the nitrogen sites constituting the amine derivative are tertiary amines.   The method for producing a fiber for reinforcing rubber according to claim 1 or 2, wherein the amine derivative is an alkylene oxide adduct of an amine.   The method for producing a rubber reinforcing fiber according to claim 3, wherein the alkylene oxide is ethylene oxide.   The method for producing a rubber-reinforcing fiber according to any one of claims 1 to 4, wherein a molar ratio of nitrogen and hydroxyl group constituting the amine derivative is 1: 2 to 1: 3.   The method for producing a fiber for reinforcing rubber according to any one of claims 1 to 5, wherein the block polyisocyanate used for the pretreatment agent is trifunctional or higher.   The method for producing a rubber reinforcing fiber according to any one of claims 1 to 6, wherein the post-treatment agent contains an isocyanate-reactive thermoplastic elastomer.