JP2005350793A - Method for producing fiber for reinforcing rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide fibers for reinforcing rubber slightly causing deterioration of fiber strengths and rubber-fiber adhesive strength even at high temperatures during vulcanization molding. <P>SOLUTION: A method for producing the fibers for reinforcing the rubber is characterized as follows. An aqueous treating liquid containing an adsorption type acid acceptor is applied to fibers and dried. Furthermore, the adsorption type acid acceptor is preferably dispersed in water and the content of the adsorption type acid acceptor is preferably 0.01-2.0 wt.% based on the fiber weight. The particle diameter of the adsorption type acid acceptor is preferably ≤20 μm and the specific surface area is preferably ≥1 m<SP>2</SP>/g. The adsorption type acid acceptor is preferably a compound of hydrotalcites and the treating liquid preferably consists essentially of an adhesive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a rubber reinforcing fiber. More specifically, the present invention relates to a rubber reinforcing fiber that is highly resistant to high-temperature vulcanization molding with rubber and is optimal for fibers and rubber composites such as hoses, belts, and tires. It relates to a manufacturing method.

  Fibers have excellent physical properties such as high strength and high Young's modulus, and are widely used to reinforce rubber structures such as hoses, belts, and tires. The fiber / rubber composite to be such a rubber structure usually undergoes a vulcanization process in which reinforcing fibers are embedded in unvulcanized rubber and heated to be integrated.

  However, this vulcanization step is essential for crosslinking the rubber and improving its physical properties, but it reduces the physical properties of the fibers or the adhesion between the fibers and the rubber. Moreover, in recent years, halogenated butyl rubber, chloroprene rubber, and chlorosulfonated polyethylene rubber, which have excellent heat resistance and gas permeability, have begun to be widely used as the rubber component of rubber structures. It is necessary to vulcanize with vulcanization temperature, and the vulcanization temperature is rising. In order to improve production efficiency, it has been required to increase the vulcanization temperature and shorten the vulcanization time.

  However, although heat-resistant anti-aging agents are known to prevent deterioration of physical properties due to high-temperature vulcanization of rubber components, the rubber composition in an unvulcanized state has a high viscosity and therefore adheres uniformly to the surface of the fiber cord. There is a problem that the deterioration of the fiber or the adhesive component for fiber / rubber cannot be sufficiently prevented.

  Therefore, in order to prevent the strength deterioration of the fiber / rubber composite due to such high-temperature vulcanization, for example, Patent Document 1 discloses that a silicate compound particle is added to a water-based adhesive matrix component as a method for improving the heat-resistant adhesive force. Although blending is disclosed, the adhesive force is improved, but it is insufficient as a means for suppressing deterioration of fiber strength due to heat.

  Further, for example, Patent Document 2 discloses that a core-sheath type composite fiber using polyethylene naphthalate fiber having excellent heat resistance is used as a sheath component as a means for suppressing deterioration of fiber strength, but the strength retention rate is increased. However, since it was a composite fiber, the initial fiber strength was insufficient, and it was insufficient to increase the absolute strength after vulcanization.

JP 2001-164233 A Japanese Patent Laid-Open No. 6-108311

  An object of the present invention is to provide a method for producing a fiber for reinforcing rubber with little deterioration in fiber strength and rubber / fiber bond strength even at a high temperature during vulcanization molding.

The method for producing a rubber reinforcing fiber of the present invention is characterized in that an aqueous treatment liquid containing an adsorption type acid acceptor is applied to the fiber and dried. Furthermore, the adsorption-type acid acceptor is water-dispersed, the content of the adsorption-type acid acceptor is 0.01 to 2.0% by weight with respect to the fiber weight, It is preferable that a particle diameter is 20 micrometers or less, and a specific surface area is 1 m < ² > / g or more. In addition, it is preferable that the adsorptive acid acceptor is a hydrotalcite compound, and the treatment liquid is mainly composed of an adhesive.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the fiber for rubber reinforcement with little deterioration of fiber strength and rubber | gum and fiber bond strength is provided even at the high temperature at the time of vulcanization molding.

  The rubber reinforcing fiber production method of the present invention is a method in which an aqueous treatment liquid containing an adsorption type acid acceptor is applied to the fiber and dried. Further, the adsorption type acid acceptor is preferably dispersed in water.

  Although there is no restriction | limiting in particular as a fiber provided with the aqueous processing liquid containing an adsorption type acid acceptor here, It is preferable that it is a synthetic fiber with high fiber strength. Examples of such synthetic fibers include polyester fibers, polyamide fibers, aromatic polyamide fibers, and the like, and are particularly effective for polyester fibers and aromatic polyamide fibers having high initial fiber strength. Among them, preferred examples of the polyester fiber include polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polybutylene naphthalate, and the like. It is also preferred that the treated fiber is pre-epoxy treated. Furthermore, it is preferable that the yarn is treated with a treatment liquid containing an epoxy compound in a non-twisted state before twisting and then twisted. In this case, when spinning or drawing the fiber, for example, a method of applying it together with a spinning oil agent in the fiber spinning process, a so-called raw yarn manufacturing method can be employed, and the epoxy component is infiltrated into the fiber cord. be able to.

  The epoxy compound that is pretreated on the fiber has at least two epoxy groups in one molecule, and the polyepoxy compound, particularly the reaction product of polyhydric alcohol and epichlorohydrin has excellent performance. Is preferable. Moreover, it is preferable that it is a compound containing an epoxy group equivalent to 0.2 mol equivalent or more per 100 g of the compound. Such an epoxy compound is usually used in the form of an emulsified solution or a solution in which it is dissolved in a small amount of a solvent using a known emulsifier such as sodium alkylbenzene sulfonate or dioctylsulfosuccinate Na salt. As the epoxy compound, an amine or imidazole curing agent can be used alone or in combination with the oil component. Thus, it is preferable that the adhesion amount of the epoxy compound previously given to a fiber is the range of 0.01 to 0.5 weight% with respect to the fiber weight. If the adhesion amount of the epoxy compound is too large, the fiber becomes very hard, the treatment after the next step becomes difficult, and the permeability of the treatment agent in the subsequent step is lowered, and as a result, the adhesion performance tends to be lowered. .

  The method for producing a rubber reinforcing fiber of the present invention is a method in which an aqueous treatment liquid containing an adsorptive acid acceptor is applied to such a fiber. Furthermore, it is preferable that the adsorptive acid acceptor contained in the aqueous processing solution is dispersed in water. In order to disperse in water, a known emulsifier such as sodium alkylbenzene sulfonate, dioctyl sulfosuccinate sodium salt, nonylphenol ethylene oxide adduct, etc. may be used for emulsification or dispersion. Since the treatment liquid is water-based, the working environment can be kept good, and the treated fibers can maintain a high adhesive force even after winding and storage.

Here, the adsorptive acid acceptor used in the present invention is mainly a mineral acid acceptor, and is preferably an acid acceptor having a positively charged surface. The particle size of the acid acceptor is preferably 20 μm or less, more preferably 0.1 to 10 μm. When the particle size is small as described above, the dispersibility is excellent and the fiber is more uniformly applied. can do. It is preferable that the specific surface area of an acid acceptor is 1 m < ² > / g or more, and it is preferable that it is 5-50 m < ² > / g. By increasing the specific surface area, the amount of acid adsorbed can be increased.

  Examples of such an acid acceptor include hydrosartite compounds represented by the following general formula, and natural or synthetic compounds in which the divalent metal is magnesium and the trivalent metal is aluminum because of its stability. It is preferable that the hydrosartite.

  There is no particular limitation on the water-based treatment liquid containing the adsorption-type acid acceptor applied to the fiber. For example, an epoxy containing an epoxy compound is treated on the surface of the fiber to bond the rubber reinforcing fiber to the rubber. Examples include a pretreatment liquid and a treatment liquid mainly composed of an RFL adhesive composed of resorcin, formalin, and latex.

  The epoxy pretreatment liquid contains a polyepoxide compound having at least two epoxy groups in one molecule similar to the epoxy compound pretreated on the fiber. The adhesion amount of the polyepoxide compound is preferably in the range of 0.1 to 10% by weight with respect to the fiber weight, and more preferably in the range of 0.1 to 5% by weight. When the adhesion amount of the polyepoxide compound is increased, the fiber tends to be hard, the permeability of the adhesion treatment liquid to be processed in the subsequent steps is lowered, and the adhesion performance is liable to be lowered.

  The resorcin / formalin / rubber latex adhesive is a mixture of an initial condensate and a rubber latex obtained by reacting resorcin / formalin (RF) in the presence of an alkali or acidic catalyst. An RFL adhesive can be used. The type of rubber latex used here is not particularly limited, and examples of the rubber latex include natural rubber latex, styrene / butadiene copolymer latex, polybutadiene rubber latex, chloroprene rubber latex, and the like.

  It is also preferable to add a blocked polyisocyanate compound to the composition of the RFL adhesive. The blocked polyisocyanate compound is an addition compound of a polyisocyanate compound and a blocking agent, and the active polyisocyanate compound is released by heating in the heat treatment step after the adhesive is applied to the fiber and the active component is released. It will occur. Examples of such polyisocyanate compounds include polyisocyanates such as tolylene diisocyanate, metaphenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl polyisocyanate, triphenylmethane triisocyanate, or these polyisocyanates and active hydrogen. Contains a terminal isocyanate group obtained by reacting a compound having two or more atoms, for example, trimethylolpropane, pentaerythritol, etc., with a molar ratio of isocyanate group (—NCO) to hydroxyl group (—OH) exceeding 1. And polyalkylene glycol adduct polyisocyanate. In particular, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenyl isocyanate exhibit preferable 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, Examples include oximes such as acetoxime, methyl ethyl ketone oxime, cyclohexane oxime, and acidic sodium sulfite. These additives are usually used in an aqueous dispersion using a dispersant, and are added alone or in combination.

  It is also preferred that the RFL adhesive composition contains a chlorophenol compound. As the chlorophenol compound used here, a compound obtained by co-condensing parachlorophenol and resorcin with formaldehyde is particularly preferable, and a compound mainly composed of a trinuclear body, a 5-nuclear body, and a 7-nuclear body is preferably exemplified.

  Further, when the fiber is treated with a plurality of treatment liquids, it is preferable that the adsorption-type acid acceptor is included in the last treatment liquid that is in direct contact with the rubber, not on the fiber contact side. Furthermore, the treatment liquid containing the adsorption type acid acceptor preferably has a certain degree of viscosity, and preferably contains a resorcin / formalin / latex adhesive as a main component.

  The content of the adsorptive acid acceptor in the treatment liquid is preferably in the range of 0.1 to 20% by weight relative to the weight of the other solid content. The rubber / fiber adhesive composition of the present invention preferably has a total solid content of 5 to 25% by weight. By setting it within this range, it is easy to control the amount of adhesion to the fiber and to maintain the liquid stability of the adhesive.

  The adhesion amount of the solid content of the rubber / fiber adhesive composition to be treated with the rubber reinforcing fiber of the present invention is preferably in the range of 0.1 to 10% by weight. Furthermore, it is in the range of 0.5 to 10% by weight, and more preferably in the range of 1 to 5% by weight. If it is less than 0.5% by weight, sufficient adhesion cannot be obtained, and if it exceeds 10% by weight, the fiber tends to be hard. In order to control the solid content adhesion amount to the fiber, means such as squeezing by a pressure roller, scraping by a scraper, 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.

  After treating the fiber with the treatment liquid containing the adsorption-type acid acceptor, for example, heat treatment is performed at a temperature of 80 to 180 ° C. for 0.5 to 5 minutes, and then at a temperature of 150 to 260 ° C. for 0.5 to 5.0 minutes. It is preferable to do. If the heat treatment temperature is too low, adhesion to rubbers tends to be insufficient, and if the heat treatment temperature is too high, the fibers tend to melt, fuse, become hard, and cause strong deterioration.

  The rubber reinforcing fiber finally obtained by the production method of the present invention preferably has an absorptive acid acceptor in an amount of 0.01 to 2.0% by weight based on the fiber weight. Moreover, it is preferable that content of adsorption type acid acceptor in the total dry weight of a processing agent is the range of 0.1-20 weight% with respect to other solid content weight.

  The rubber reinforcing fiber obtained by the method for producing a rubber reinforcing fiber of the present invention can adsorb chlorine ions generated in the rubber fiber structure by the adsorptive acid acceptor, and prevent deterioration of the fiber. A rubber reinforcing fiber having high resistance to high-temperature vulcanization during molding can be obtained. Furthermore, since the adsorption-type acid acceptor is contained in the aqueous processing solution, in addition to making the working environment suitable, it can be stably present in the coating film and uniformly cover the fiber surface. It is possible to suppress local strength deterioration. In particular, the adsorption-type acid acceptor used in the present invention has an acid adsorption function, and therefore, even during high-temperature vulcanization in a molding process when a rubber structure containing a halogen group, for example, chlorinated butyl rubber and a reinforcing fiber are integrated. As a result, the rubber structure reinforced with the fibers obtained in the present invention can sufficiently exhibit excellent characteristics.

  The rubber reinforcing fiber obtained in the present invention can be co-vulcanized in rubber to form a fiber rubber composite. In particular, heat resistance of α-olefin / non-conjugated diene copolymer, halogenated butyl rubber (X-IIR, X = Cl, Br), chloroprene rubber, chlorosulfonated polyethylene rubber, etc. that require high-temperature vulcanization as rubber In addition, it is preferable to use a rubber excellent in gas permeability resistance. By using a rubber reinforcing fiber containing an acid acceptor in the surface layer, it is possible to obtain a rubber / fiber composite having high fiber strength and high fiber / rubber adhesion strength even after high temperature vulcanization.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the measurement of the characteristic in an Example was performed with the following measuring method.

(1) Cord peeling adhesive strength This indicates the peeling adhesive strength between the treated cord and rubber using the treated cord as a sample. Twenty-five bonded fiber cords are arranged between 25.4 mm (1 inch). Then, it is embedded in unvulcanized rubber and vulcanized for a predetermined time by steam vulcanization. The force required to peel the cord from the rubber with this test piece is indicated by N / 25.

(2) Cord strength retention The fiber cord was taken out from the rubber fiber composite after vulcanization, and the ratio with the strength of the adhesive treatment cord before vulcanization was calculated to obtain the heat aging resistance of the cord.
(Heat aging resistance of cord (%))
= (Strength of fiber cord after vulcanization) / (Strength of adhesive treatment cord) X100

[Example 1]
A resorcin / formalin initial condensate (Sumikanol 700S, manufactured by Sumitomo Chemical Co., Ltd., 65% aqueous solution) reacted with an acidic catalyst is added to water to which an aqueous caustic soda solution and an aqueous ammonia solution are added, and the mixture is sufficiently stirred and dispersed. To this, formalin is added so that the resorcin / formalin ratio is 1/2 (molar ratio) and mixed uniformly. Next, the weight ratio (RF / L) of the resorcin-formalin condensate (RF) to the latex is 1/9 for vinylpyridine / styrene / butadiene terpolymer rubber latex (manufactured by Nippon Zeon Co., Ltd., 2518FS). Mixed. Next, blocked isocyanate (Elastolon BN-69, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., diphenylmethane diisocyanate methyl ethyl ketone oxime block 40% aqueous dispersion) was 14% (weight ratio) in terms of solid content with respect to the RFL adhesive. In addition, synthetic hydrotalcite (Mg _4.3 Al ₂ (OH) _12.6 CO ₃ .4H ₂ O, diameter 0.43 μm, specific surface area 12 m ² / g, Kyowa Chemical Industry Co., Ltd.), an adsorptive acid acceptor A DHT-4) 27% aqueous emulsion was blended so that the final solid content ratio was 5% by weight and aged for 24 hours. Further, just before use, a special chlorophenol compound (Denabond E, manufactured by Nagase Kasei Kogyo Co., Ltd., 20% solution) is added so that the solid content ratio with respect to RFL is 1/2 (weight ratio), and the mixture is sufficiently stirred to be treated. Thus, an adhesive composition for rubber-reinforced fibers was obtained. The solid content concentration of the finally obtained treatment liquid was 17%, and the adsorption type acid acceptor was 5% by weight with respect to the weight of the solid content of the RFL adhesive. In order to control the viscosity and adhesion amount of the adhesive composition, water was added to the treatment agent to dilute the solid content concentration to 10%.

  On the other hand, a cord (1100 dtex / 3) which is twisted and twisted at 10 T / 10 cm while drawing three multifilaments of polyethylene terephthalate fiber (manufactured by Teijin Techno Products Co., Ltd., 1100 dtex / 250 filament) previously provided with a polyepoxide compound in the yarn-making process. ) Was prepared.

  The cord is immersed in the rubber / fiber adhesive composition using a computer treater (CA Ritsuler Co., Ltd., fiber cord processor), dried at 150 ° C. for 2 minutes, and then further 240 Heat treatment was performed at a temperature of 1 ° C. for 1 minute to obtain a polyester cord as a fiber material for rubber reinforcement. The polyester cord had 2.8% by weight of the solid content of the adhesive composition. The adhesion amount of the adsorptive acid acceptor with respect to the fiber weight was 0.15% by weight.

  Using the polyester cords thus obtained, 25 pieces were arranged on a chlorinated butyl rubber unvulcanized rubber sheet at 25.4 mm (1 inch), vulcanized at 150 ° C. for 60 minutes, and vulcanized at 180 ° C. for 30 minutes. The cord strength after vulcanization was measured. Furthermore, the fiber / rubber peel adhesion after vulcanization at 180 ° C. for 30 minutes was measured. The results are shown in Table 1.

[Example 2]
The treatment and evaluation were performed in the same manner as in Example 1 except that the amount of the synthetic hydrotalcite, which is an adsorptive acid acceptor in the adhesive composition, was changed from 5 wt% to 1 wt%. . The solid content concentration of the adsorption-type acid acceptor in the treatment liquid was 1% by weight with respect to the weight of the solid content of the RFL adhesive, and the solid content adhered to the fiber of the acid acceptor was 0.03% by weight. . The results are also shown in Table 1.

[Comparative Example 1]
The treatment and evaluation were performed in the same manner as in Example 1 except that the amount of the synthetic hydrotalcite, which is an adsorptive acid acceptor in the adhesive composition, was changed to none. The results are also shown in Table 1.

  The fiber-reinforced rubber composite using the rubber reinforcing fiber according to the production method of the present invention exhibits a high strength retention even after high-temperature vulcanization, and thus has an excellent rubber reinforcing effect. In particular, it is optimal for applications such as hoses and belts using special rubber containing high strength fibers and halogen groups.

Claims (8)

  A method for producing a rubber-reinforcing fiber, comprising applying an aqueous treatment liquid containing an adsorption-type acid acceptor to a fiber and drying the fiber.   The method for producing a rubber-reinforcing fiber according to claim 1, wherein the adsorptive acid acceptor is dispersed in water.   The method for producing a rubber reinforcing fiber according to claim 1 or 2, wherein the content of the adsorptive acid acceptor is 0.01 to 2.0% by weight with respect to the fiber weight.   The method for producing a rubber-reinforcing fiber according to any one of claims 1 to 3, wherein the adsorption-type acid acceptor has a particle size of 20 µm or less. The method for producing a rubber-reinforcing fiber according to any one of claims 1 to 4, wherein the adsorption-type acid acceptor has a specific surface area of 1 m ² / g or more.   The method for producing a fiber for reinforcing rubber according to any one of claims 1 to 5, wherein the adsorptive acid acceptor is a hydrotalcite compound.   The method for producing a rubber reinforcing fiber according to any one of claims 1 to 5, wherein the treatment liquid contains an adhesive as a main component.   8. The method for producing a fiber for reinforcing rubber according to claim 7, wherein the adhesive comprises a resorcin / formalin / latex adhesive as a main component.