JP2009299221A - Synthetic fiber for reinforcing rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synthetic fiber for reinforcing a rubber which achieves excellent adhesion between the rubber and the fiber at high temperature. <P>SOLUTION: A pre-treating agent comprising a polyepoxide compound and a rubber latex, and a resorcinol-formalin-latex based adhesion-treating agent are attached to the synthetic fiber for reinforcing the rubber, wherein that the epoxy equivalent of the polyepoxide compound is 200 g/equivalent or less; the viscosity at a concentration of 100% is 400 mPa s or more; the solubility in water is 3 wt.% or more. Preferably, the epoxy component is the polyglycidyl ether of one of sorbitol, glycerol, and ethylene glycol, the rubber latex content of the pre-treating agent is 10 wt.% or less; and the adhesion-treating agent contains a blocked polyisocyanate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a synthetic fiber for rubber reinforcement, and more particularly to a synthetic fiber for rubber reinforcement excellent in heat-resistant adhesive strength.

  Polyester fibers typified by polyethylene terephthalate and polyethylene naphthalate fibers, and synthetic fibers such as aromatic polyamide fibers have excellent physical properties such as high strength and high Young's modulus. Widely used as a rubber reinforcing fiber for hoses and belts. However, since the surface of these synthetic fibers is relatively inactive, the adhesiveness with a matrix such as rubber or resin is insufficient as it is, and the physical properties of the fibers are fully exhibited. Absent.

  For this reason, a chemical treatment method for treating the surface of the fiber with various chemicals, for example, Patent Document 1, discloses a compound containing a vinyl halide group having a film formation temperature of 200 ° C. or less, a polyepoxide compound, and a rubber latex in one bath. After treatment with the treatment agent (1) in which the content of the compound containing the vinyl halide group is in the range of 3 to 85% by weight with respect to the solid content of the treatment agent, A method of treating polyester fiber for reinforcing rubber, characterized by treatment with a treatment agent (2) containing formalin rubber latex, is disclosed. This method can dramatically reduce the adhesion amount of the adhesive and is economically excellent.

However, this treatment method has a problem that the peel adhesiveness at high temperature is insufficient, and the treatment method cannot be used in severe applications.
JP 2000-234275 A

  The present invention has been made against the background of the above circumstances, and is to provide a synthetic fiber for rubber reinforcement capable of realizing excellent adhesion between rubber and synthetic fibers at high temperatures.

  The synthetic fiber for rubber reinforcement of the present invention is a synthetic fiber for rubber reinforcement to which a pretreatment agent containing a polyepoxide compound and a rubber latex and a resorcin / formalin / latex adhesive treatment agent are adhered, and an epoxy of a polyepoxide compound The equivalent is 200 g / equivalent or less, the viscosity at 100% concentration is 400 mPa · s or more, and the solubility in water is 3% by weight or more.

  In addition, the epoxy component is a polyglycidyl ether of sorbitol, glycerin, or ethylene glycol, the rubber latex content of the pretreatment agent is 10% by weight or less, and the rubber latex is vinyl pyridine / styrene / butadiene / tar. It is preferably a polymer latex, a styrene component content ratio of the vinylpyridine / styrene / butadiene / terpolymer latex is 20 to 40% by weight of the total weight, and the adhesive treatment agent contains a block polyisocyanate.

  ADVANTAGE OF THE INVENTION According to this invention, the synthetic fiber for rubber reinforcement which can implement | achieve the adhesion | attachment excellent in rubber | gum and synthetic fiber at high temperature is provided.

  Examples of the rubber reinforcing synthetic fiber of the present invention include polyester fiber and aromatic polyamide fiber. More specifically, for example, as a polyester fiber, a fiber made of polyester having terephthalic acid or naphthalenedicarboxylic acid as a main acid component and ethylene glycol, 1,3-propanediol or tetramethylene glycol as a main glycol component. Is preferably used. Representative examples of the aromatic polyamide fiber include polyparaaminobenzamide, polyparaphenylene terephthalamide, polyparaaminobenzhydrazide terephthalamide, polyterephthalic acid hydrazide, polymetaphenylene isophthalamide, and copolymers thereof. Can be mentioned.

  The synthetic fiber of the present invention includes various fiber aggregate forms such as yarns, cords, nonwoven fabrics, woven and knitted fabrics, and in particular, cords with twisted yarns exhibit the strength of the synthetic fibers more effectively. It is preferable for this purpose. There are no particular limitations on synthetic fiber denier, filament count, cross-sectional shape, fiber properties, microstructure, polymer properties (terminal carboxyl group concentration, molecular weight, etc.), presence or absence of additives in the polymer, etc. In order to make effective use of strength, it is preferable to have a circular cross-sectional shape.

  The synthetic fiber for rubber reinforcement of the present invention is a fiber for rubber reinforcement in which a pretreatment agent containing block polyisocyanate and epoxy and a so-called RFL adhesive of resorcin / formalin / latex are attached. It is essential that the epoxy equivalent of the polyepoxide compound in the pretreatment agent is 200 g / equivalent or less, the viscosity at 100% concentration is 400 mPa · s or more, and the solubility in water is 3% by weight or more.

  The pretreatment agent of the present invention is required to contain the epoxy as described above. The epoxy here is a polyepoxide compound (B), and in particular, at least two epoxy groups per molecule. It is preferable that it is a compound to contain. Specific examples of epoxies include reaction products of polyhydric alcohols such as ethylene glycol, glycerol, sorbitol, pentaerythritol, and polyethylene glycol with halogen-containing epoxides such as epichlorohydrin, resorcin, bis (4-hydroxyphenyl) Reaction products of polyhydric phenols such as dimethylmethane, phenol-formaldehyde resin, resorcinol-formaldehyde resin and the above halogen-containing epoxides, polyepoxide compounds obtained by oxidizing unsaturated compounds with peracetic acid or hydrogen peroxide, 3,4-epoxycyclohexylene epoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylenecarboxylate, bis (3,4-epoxy-6-methyl-cyclohexylmethyl) a Or the like can be mentioned Bate. Of these, reaction products of polyhydric alcohols such as ethylene glycol, glycerol, sorbitol, pentaerythritol, and polyethylene glycol and epichlorohydrin, that is, polyglycidyl ether compounds of polyhydric alcohols are preferable because they exhibit excellent performance.

  Here, in the present invention, it is necessary that the polyepoxide compound has an epoxy equivalent of 200 g / equivalent or less, a viscosity at 100% concentration of 400 mPa · s or more, and a solubility in water of 4% by weight or more. . Furthermore, the epoxy equivalent is preferably 140 to 200 g equivalent, the viscosity at 100% concentration is 500 to 10,000 mPa · s, the solubility in water is 3 to 20% by weight, and further 4% by weight or more. Preferably there is. When the solubility is less than 3% by weight, a surfactant for dispersing in water is required, and adhesion inhibition occurs. On the other hand, when the viscosity is less than 400 mPa · s, the molecular weight is small and the crosslinkability is lowered, and the adhesiveness at high temperature cannot be ensured. The molecular weight is preferably 5000 or more. By satisfying such a large molecular weight and epoxy equivalent, high-temperature adhesion that is not easily affected by heat can be realized.

  The blocked polyisocyanate compound used together with the polyepoxide compound in the pretreatment agent is an addition reaction product of the polyisocyanate compound and the blocking agent, and the block component is released by heating to produce an active polyisocyanate compound. It is. 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 Examples of the compound having phenol include phenols such as phenol, thiophenol, cresol and resorcinol, aromatic secondary amines such as diphenylamine and xylidine, lactams such as phthalic imides, caprolactam and valerolactam, acetoxime, and methylethylketoxime. And oximes such as cyclohexanone oxime and acidic sodium sulfite.

  In addition to the blocked polyisocyanate compound (A) and polyepoxide compound (B), the pretreatment agent used in the present invention further includes a rubber latex (L) and a surfactant (S) that lowers the surface tension. It is preferable.

  As the rubber latex (L) added to the pretreatment agent in the present invention, vinylpyridine / styrene / butadiene terpolymer latex alone, or natural rubber latex, styrene / butadiene copolymer latex, nitrile rubber latex, chlorobrene rubber latex, The combined use of ethylene / propylene / diene monomer latex is preferred. When used in combination, the proportion of vinylpyridine / styrene / butadiene terpolymer latex is preferably 30% by weight or more of the latex components. Moreover, the case where the content ratio of the styrene component of the vinylpyridine / styrene / butadiene / terpolymer latex is 20 to 40% by weight of the total weight is preferable.

  In general, the pretreatment agent attached to the surface of the synthetic fiber in the present invention is processed into a synthetic fiber as a solution. At this time, when the solution (1) of the pretreatment agent is the blocked polyisocyanate compound (A), the polyepoxide compound (B), and the rubber latex (L) as described above, the blending weight ratio of each component is as follows. , (A) / (B) is preferably 5/5 to 1/9, and (L) / {(A) + (B)} is preferably 1/20 to 1/1. In particular, by setting the above (A) / (B) in the range of 5/5 to 1/9, the adhesiveness at high temperature is further improved.

  Further, by setting the (L) / {(B) + (A)} to 1/20 or more, the treated fiber can be kept flexible, and the fatigue resistance is lowered due to the cord becoming hard. Adhesiveness improves by preventing co-vulcanization with the latex of the adhesive agent and the rubber | gum which are to be adhered while preventing. On the other hand, when this ratio becomes too high, for example, when (L) / {(B) + (A)} exceeds 1/1, the affinity to the polyester fiber side is insufficient, so that the adhesiveness is reversed. Tends to decrease.

  In order to adhere such a solution (1) of the pretreatment agent to the synthetic fiber, means such as contact with a roller, application by spraying from a nozzle, or immersion in a solution can be employed. Further, the solid content adhesion amount to the synthetic fiber is exemplified by a range of 1 to 30% by weight, and preferably 2 to 15% by weight. In order to control the amount of solids adhering to the synthetic fiber, it can be performed by means of squeezing with a pressure roller, scraping with a scrubber, etc., blowing off with air blowing, suction, beater, etc. It may be attached once.

  The synthetic fiber for reinforcing rubber of the present invention is one in which a resorcin / formalin / latex-based adhesive treatment agent is attached in addition to the pretreatment agent containing the block polyisocyanate and epoxy as described above.

  The adhesive of the present invention is preferably applied to the synthetic fiber as a solution (2). As the solution (2) of the resorcin / formalin / rubber latex (RFL) adhesive used at that time, resorcin and formaldehyde are used. The molar ratio is preferably in the range of 1: 0.8 to 1: 5, and more preferably in the range of 1: 1 to 1: 4. If the amount of formaldehyde added is too small, the crosslink density of the condensate of resorcin / formalin is lowered and the molecular weight is lowered, so that the adhesive strength may be lowered by reducing the cohesive force of the adhesive layer. 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. There is a tendency that the fibers of the present invention are remarkably hard and the strength and fatigue properties are lowered.

  The adhesive treatment agent used in the present invention preferably contains a blocked polyisocyanate compound. The addition ratio of the blocked polyisocyanate compound to the adhesive treatment agent is preferably 0.5 to 30% by weight, more preferably 1.0 to 20% by weight, based on the total amount of resorcin / formalin / rubber latex (RFL). A range is preferred. If the added amount is too small, the effect of improving the adhesive strength is small, and if the added amount is too large, the viscosity of the adhesive is remarkably increased and the fiber processing operation becomes difficult, and the treated fiber becomes extremely hard, It is not preferable because strength and fatigue tend to decrease.

  The optimum blending ratio of resorcin / formalin and rubber latex in the solution (2) of the adhesive treatment agent varies depending on the addition ratio of the blocked polyisocyanate compound, but the solids ratio is resorcin / formalin: rubber. The latex (RFL) is preferably in the range of 1: 3 to 1:12, particularly preferably in the range of 1: 3 to 1: 6. If the ratio of the rubber latex is too small, the treated polyester fiber tends to be hard and fatigue resistance tends to decrease, and the latex in the pretreatment solution (1) and the rubber that is the adherend are coexisting. Insufficient vulcanization may result in poor adhesion. On the contrary, when the ratio of the rubber latex in the adhesive is too large, the strength as an adhesive film is reduced, and the adhesive force and the rubber adhesion rate tend to be reduced.

  The solution (2) to be treated as the adhesion treating agent of the present invention preferably has a total solid content concentration in the range of 1 to 30% by weight, more preferably 2 to 25% by weight, and still more preferably 5%. It can be used in an amount of ˜20% by weight. When the total solid concentration of the adhesive treatment solution (2) is lower than the above range, the surface tension of the adhesive solution increases, and the uniform adhesion to the polyester fiber surface decreases, and the solid content adheres. When the amount decreases, the adhesiveness decreases, and conversely, when the total solid content concentration is higher than the above range, the solid content is excessively hard and the fatigue resistance decreases. Cheap.

  Further, in order to adhere the solution (2) of the adhesion treatment agent to the synthetic fiber, means such as contact with a roller, application by spraying from a nozzle, or immersion in a solution can be employed. Further, the solid content adhesion amount to the synthetic fiber is exemplified by a range of 0.1 to 10% by weight, preferably a range of 0.2 to 7% by weight, more preferably 0.5 to 6% by weight. The thing in the range of is good. In order to control the amount of solids adhering to the synthetic fiber, as described above, it can be performed by means of squeezing with a pressure roller, scraping with a scrubber, etc., blowing off with air blowing, suction, beater means, and the amount of adhesion is large. In order to do so, it may be attached multiple times.

  In order to obtain the synthetic fiber for reinforcing rubber of the present invention, the synthetic fiber is treated using the solution (1) and the solution (2) as described above, and then at 50 ° C. or higher and 10 ° C. from the melting point of the synthetic fiber. Drying and heat treatment in the low temperature range. More preferably, for example, when the fiber is a polyester fiber, it is dried and heat-treated at a temperature range of 220 to 250 ° C. for 0.5 to 5 minutes, preferably 1 to 3 minutes. If the drying / heat treatment temperature is too low, adhesion to rubber tends to be insufficient, and if the drying / heat treatment temperature is too high, the synthetic fiber melts and melts, resulting in a decrease in fiber strength. There is.

  The synthetic fiber for reinforcing rubber of the present invention thus obtained is excellent in heat resistance, and as a synthetic fiber for reinforcing rubber for tires, hoses, belts, etc., maintains high performance even in a particularly severe state. Are preferably used.

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

(1) Solubility in water As a method for measuring the solubility of an epoxy compound in water, first, a predetermined amount of an epoxy compound was added to 20 ° C. ion-exchanged water, stirred for 5 minutes, and then allowed to stand for 5 minutes. At this time, when the epoxy compound was not phase-separated and was colorless and transparent, it was considered that it was dissolved, and the upper limit concentration was defined as solubility.
Solubility = (weight of epoxy added at the upper limit concentration) / (weight of epoxy added at the upper limit concentration + weight of water)

(2) Initial peel adhesive strength, heat-resistant peel adhesive strength This indicates the adhesive strength between the treatment cord and rubber. The cords are arranged at 30 / 2.54 cm (inch) and sandwiched between uncured rubber sheets containing a carcass composed mainly of 0.5 mm thick natural rubber. These sheets are stacked so as to go straight and pressed at a temperature of 150 ° C. for 30 minutes at a pressing pressure of 50 kg / cm ² (initial peel adhesive force), or at a temperature of 180 ° C. for 40 minutes at a pressure of 50 kg / cm ² . Vulcanize with pressure (heat-resistant peel adhesion), then cut into strips along the cord direction at room temperature. The force required to peel the sheet along the strip at a speed of 200 mm / min in the direction of 90 degrees with respect to the rubber sheet surface is indicated by N / 2.54 cm (inch), and the initial peel adhesive strength and heat-resistant peel. Adhesive strength.

(3) High temperature peel adhesion The above sample prepared for initial adhesion measurement was measured under the same measurement conditions as above, except that the measurement ambient temperature was changed to 150 ° C. did.

[Example 1]
As a solution of the pretreatment agent (treatment agent (1)), a sorbitol-based polyepoxide compound (epoxy equivalent 170 g / equivalent, 100% viscosity 4600 mPa · s, solubility in water 4 wt%, Sakamoto Yakuhin Kogyo SR-SEP), ε Caprolactam blocked MDI (S3 manufactured by Meisei Chemical Industry Co., Ltd.) and vinylpyridine / styrene / butadiene terpolymer rubber latex (manufactured by Nippon A & L Co., Ltd., Pyratex) are each 80 wt%, 10 wt%, 10 wt% in solid content. Thus, a mixed solution having a total solid content of 10% by weight mixed at a ratio of (treatment agent (1)) was obtained.

  On the other hand, as an adhesive treating agent solution (treating agent (2)), an initial condensate having a resorcin / formalin (R / F) molar ratio of 1 / 0.6 and a solid concentration of 65% by weight under alkaline conditions. To 9 wt% aqueous solution. To this, 99 parts by weight and 104 parts by weight of 41% vinylpyridine / styrene / butadiene turbolimer latex (manufactured by Nippon A & L, Pyratex) and water are added to 57 parts by weight of the 9% resorcin / formalin aqueous solution, respectively. To this solution was added 3 parts by weight of formalin and 30 parts by weight of a 33% by weight acetoxime blocked diphenylmethane diisocyanate dispersion (manufactured by Meisei Chemical Industry Co., Ltd., DM6011), and a solution having a solid content concentration of 20% by weight aged for 48 hours. Obtained (treatment agent (2)).

  A multi-filament yarn of 1670 dtex / 384 filament made of polyethylene terephthalate with an intrinsic viscosity of 0.95 is used. The multi-filament yarn is subjected to a lower twist at 40 T / 10 cm, and two of these are twisted together to give an upper twist at 40 T / cm. To obtain a cord of 3340 dtex / 768 filament.

  The cord was immersed in the treatment agent (1) using a contributor processing machine (CA Ritzler Co., Ltd., tire cord processing machine), dried at a temperature of 130 ° C. for 2 minutes, and subsequently 240 ° C. Then, after being immersed in the treatment agent (2), it was dried at a temperature of 170 ° C. for 2 minutes, and subsequently subjected to a heat treatment at a temperature of 240 ° C. for 1 minute. The resulting tire cord had 2.1% by weight of the treating agent (1) and 2.2% by weight of the treating agent (2) as the solid content of the treating agent. The obtained treated cord was embedded in an unvulcanized rubber containing carcass containing natural rubber as a main component and evaluated by the above method after vulcanization. The results are shown in Table 1.

[Example 2]
Example 1 except that a polyglycerol polyepoxide compound (Nagase Chemtex, EX521) having an epoxy equivalent of 183 g / equivalent, a 100% viscosity of 4400 mPa · s, and a solubility in water of 12% by weight was used instead of the sorbitol-based polyepoxide compound. Processing was carried out in the same manner. The evaluation results are also shown in Table 1.

[Comparative Example 1]
The same treatment as in Example 1 except that a sorbitol-based polyepoxide compound having an epoxy equivalent of 167 g / equivalent, a 100% viscosity of 11800 mPa · s, and a solubility in water of 2% by weight (Nagase Chemtex, EX611) was used as the sorbitol-based polyepoxide compound. Went. The evaluation results are also shown in Table 1.

[Comparative Example 2]
Example 1 and Example 1 were used except that a diglycerol polyepoxide compound (Nagase ChemteX, EX421) having an epoxy equivalent of 159 g / equivalent, a 100% viscosity of 650 mPa · s, and a solubility in water of 35% by weight was used instead of the sorbitol-based polyepoxide compound. Processing was carried out in the same manner. The evaluation results are also shown in Table 1.

[Comparative Example 3]
Except for using a glycerol-based polyepoxide compound (Nagase Chemtex, EX313) having an epoxy equivalent of 141 g / equivalent, a 100% viscosity of 150 mPa · s, and a solubility in water of 60% by weight instead of the sorbitol-based polyepoxide compound, the same as in Example 1. Was processed. The evaluation results are also shown in Table 1.

Claims (6)

  A synthetic fiber for reinforcing rubber to which a pretreatment agent containing a polyepoxide compound and a rubber latex and an adhesion treatment agent of resorcin / formalin / latex are attached, wherein the epoxy equivalent of the polyepoxide compound is 200 g / equivalent or less, A synthetic fiber for reinforcing rubber having a viscosity at 400% concentration of 400 mPa · s or more and a solubility in water of 3% by weight or more.   The synthetic fiber for rubber reinforcement according to claim 1, wherein the epoxy component is a polyglycidyl ether of sorbitol, glycerin or ethylene glycol.   The rubber reinforcing synthetic fiber according to claim 1 or 2, wherein the rubber latex content of the pretreatment agent is 10% by weight or less.   The synthetic fiber for rubber reinforcement according to any one of claims 1 to 3, wherein the rubber latex is a vinylpyridine / styrene / butadiene / terpolymer latex.   The synthetic fiber for reinforcing rubber according to claim 4, wherein the content ratio of the styrene component in the vinylpyridine / styrene / butadiene / terpolymer latex is 20 to 40% by weight of the total weight.   The synthetic fiber for rubber reinforcement according to any one of claims 1 to 5, wherein the adhesive treatment agent contains block polyisocyanate.