JP2006233354A - Method for producing rubber-reinforcing fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a rubber-reinforcing fiber excellent in heat resistant bonding force with the rubber. <P>SOLUTION: This method for producing the rubber-reinforcing fiber is characterized by treating the fiber with a plasma in a medium containing the gas of alkenes and/or alkynes, then treating with a first treating liquid containing a polyepoxide compound, a blocked isocyanate compound and rubber latex, and a second treating liquid containing mainly resorcinol, formalin and rubber latex in this order. Further, it is preferable that the fiber is a synthetic fiber, the medium for the plasma treatment is a compound consisting mainly of nitrogen and the concentration of the alkenes and/or alkynes on the plasma treatment is 0.1-15 vol%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing rubber reinforcing fibers, and more particularly to a method for producing rubber reinforcing fibers having extremely high heat-resistant adhesion to rubber.

  In fiber reinforced rubber composites widely used as industrial materials, the adhesive strength of reinforcing fibers to the matrix greatly affects physical properties such as strength and fatigue. As an example of the adhesion treatment method, a resin mainly composed of resorcin-formalin-rubber latex (RFL) which is an adhesion treatment liquid for rubber / fiber used in tires, hoses, and belts is treated for adhesion treatment. It has long been known as a liquid.

  However, in recent years, in the field of hoses and belts, for example, the temperature of the engine room of an automobile, which is the main application thereof, has increased, and therefore, rubber materials having excellent high temperature characteristics have been used. Examples of these rubbers are butyl rubber, ethylene propylene rubber, nitrile rubber, chloroprene rubber, chlorosulfonated ethylene rubber and the like. However, these special rubbers have a problem that their chemical structure has few double bonds and is poor in reactivity, so that adhesion is very difficult.

  For this reason, at the time of adhesion between the fiber and the rubber, a method (Patent Document 1) of applying a processing agent in which a special chlorophenol compound and the above-mentioned RFL are added or a processing agent containing a polyallylamine compound after the RFL processing agent is applied. (Patent Document 2) has been proposed, but none of them has yet obtained a sufficiently satisfactory adhesive force, particularly a heat resistant adhesive force.

JP-A-7-138880 JP-A-10-280280

  An object of the present invention is to provide a method for producing a rubber reinforcing fiber having excellent heat-resistant adhesive strength with rubber.

  In the method for producing a rubber reinforcing fiber of the present invention, the fiber is subjected to plasma treatment in a medium containing an alkene and / or alkyne gas, and then a first treatment liquid containing a polyepoxide compound, a blocked isocyanate compound, and a rubber latex; The second treatment liquid mainly comprises resorcin, formalin, and rubber latex.

  Furthermore, the fiber is a synthetic fiber, the medium during the plasma treatment is mainly nitrogen, or the concentration of alkenes and / or alkynes during the plasma treatment is 0.1 to 15 volumes. % Is preferred.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the fiber for rubber reinforcement excellent in the heat resistant adhesive force with rubber | gum is provided.

  The present invention is a method for producing a rubber reinforcing fiber, in which a fiber is subjected to plasma treatment in a medium containing an alkene and / or alkyne gas, and then sequentially treated with a first treatment liquid and a second treatment liquid.

  Here, the fiber used in the production method of the present invention is not particularly limited, and organic fibers such as natural fibers, semi-synthetic fibers, and synthetic fibers, and inorganic fibers such as carbon fibers and glass fibers can be used. In particular, synthetic organic fibers excellent in physical properties such as strength and inorganic fibers are preferable. Examples of synthetic fibers include polyethylene terephthalate, polyester typified by polybutylene terephthalate, nylon 6 and aliphatic typified by nylon 66. It is preferably a fiber obtained by spinning and drawing a polyamide, an aromatic polyamide, and a polymer comprising polyvinyl alcohol and polyethylene. The above-mentioned fibers are desirably drawn using a high-viscosity polymer at a high draw ratio in order to increase the strength. Moreover, as a carbon fiber which is a preferable inorganic fiber, the PAN type fiber which baked the organic fiber is mentioned. Further, the denier of the fiber, the number of filaments, the cross-sectional shape, the fiber physical properties, the fine structure, the polymer properties (such as the concentration of powdery asthma group, the molecular weight), the presence or absence of additives in the polymer are not limited at all.

  Of course, the form of the fiber material varies depending on the application, but the treatment of the present invention can be applied to any form of fiber material. For example, after the plasma treatment in a yarn state, the cord or woven fabric may be formed, and then the treatment may be performed with the first treatment liquid and the second treatment liquid. There may be a cloth, and then the treatment with the second treatment liquid may be performed, or the plasma treatment and the treatment with the first treatment liquid may be performed in the form of a cord, and then the treatment with the second treatment liquid may be performed as a woven fabric. As described above, in the production method of the present invention, the shape at the time of the treatment is not limited at all, and it can be treated in various fiber aggregate forms such as yarn, cord, nonwoven fabric, woven or knitted fabric, and this The manufacturing process of the invention can be carried out.

The present invention is a production method which requires such a fiber to be plasma-treated in a medium containing an alkene and / or alkyne gas.
This plasma processing will be described below.

  Examples of the alkenes or alkynes include simple substances such as acrylic acid, ethylene, butadiene, 2-vinylpyridine, N-vinyl-2-pyrrolidone, acetylene, or a mixture thereof. From the viewpoint of reactivity and the like, alkynes that are easier to polymerize than alkenes are preferable, and further, those having a low molecular weight such as butadiene are easily gasified. Moreover, it is preferable that the medium at the time of the plasma treatment is mainly composed of nitrogen in addition to the gas of alkenes and / or alkynes. When the nitrogen gas concentration is lowered, the surface activity effect tends to decrease. The gas medium other than nitrogen is preferably a component contained in the air such as oxygen, carbon dioxide, or argon, or a rare gas such as helium, neon, or xenon.

  The concentration of the alkene and / or alkyne gas during the plasma treatment is preferably in the range of 0.1 to 15% by volume. This treatment is preferable because the plasma concentration of alkenes or alkynes is 0.1 to 15%, which is sufficiently diluted with nitrogen plasma. The total concentration of alkene or alkyne plasma and nitrogen plasma is preferably 90 to 100%.

  An active film that contributes to adhesion on the surface of the fiber can be obtained by such plasma treatment. The active film on the fiber has a strong chemical bonding force with the fiber, and the surface of the active film has a strong chemical bonding force with epoxy or the like.

  The treatment time in the medium containing the plasma-treated alkene and / or alkyne gas is preferably 5 to 300 seconds. If the time is short, the thickness of the active film obtained by the plasma treatment tends to be difficult to obtain sufficiently. If the time is too long, the active film tends to be too thick, and a low molecular weight laminate tends to be generated on the surface of the fiber. The adhesive force may be reduced due to cohesive failure of the film itself.

  The pressure condition is preferably normal pressure. Here, the normal pressure means 10,000 Pa to 110,000 Pa, and preferably under almost atmospheric pressure of 90,000 to 105,000 Pa, pressure adjustment becomes easy and the process becomes simple. This is also preferable. By performing processing at normal pressure in this way, a large and special device is not required, the device can be miniaturized, the manufacturing cost can be reduced, and continuous processing that has been difficult in the past can be performed, greatly increasing the production volume. Can do.

  The plasma treatment is preferably performed by a glow discharge method. In order to perform the treatment under normal pressure, a pulse electric field is generally applied.

  The production method of the present invention is a method in which the plasma-treated fiber is treated in order with the first treatment liquid and the second treatment liquid. And as a 1st process liquid, it is essential to contain a polyepoxide compound, a blocked isocyanate compound, and rubber latex.

  As the polyepoxide compound used in the present invention, a compound containing 2 g equivalent or more of at least 2 epoxy groups per 1 kg of the compound is preferable. Specifically, reaction products of polyhydric alcohols such as ethylene glycol, glycerol, sorbitol, pentaerythritol, polyethylene glycol and halogen-containing epoxides such as epichlorohydrin, resorcin, pis (4-hydroxyphenyl) dimethylmethane, phenol -Reaction products of polyhydric phenols such as formaldehyde resin, resorcinol-formaldehyde resin and the above halogen-containing epoxides, polyepoxide compounds obtained by oxidizing unsaturated compounds with peracetic acid or hydrogen peroxide, ie 3, 4 -Epoxycyclohexene epoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexenecarboxylate, bis (3,4-epoxy-6-methyl-cyclohexylmethyl) adipate, etc. It is possible. Among these, a reaction product of a polyhydric alcohol and epichlorohydrin, that is, a polyglycidyl ether compound of a polyhydric alcohol is preferable because it exhibits excellent performance.

  The blocked polyisocyanate compound is an addition compound of a polyisocyanate compound and a blocking agent, and releases a block component by heating to produce an active polyisocyanate compound.

  Examples of the polyisocyanate compound include polyisocyanates such as tolylene diisocyanate, metaphenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, triphenylmethane triisocyanate, or two or more of these polyisocyanates and active hydrogen atoms. Terminal isocyanate group-containing polyol adduct polyisocyanate obtained by reacting a compound having, for example, trimethylolpropane, pentaerythritol, etc. with a molar ratio of isocyanate group (—NCO) to hydroxyl group (—OH) exceeding 1. Is mentioned. In particular, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate are preferable because they exhibit excellent performance.

  Examples of the blocking agent for the blocked polyisocyanate compound include phenols such as phenol, thiophenol, cresol, and resorcinol, aromatic secondary amines such as diphenylamine and xylidine, phthalimides, caprolactam, valerolactam, and the like. Examples include lactams, acetoximes, methyl ethyl ketone oximes, oximes such as cyclohexane oximes, and acidic sodium sulfite.

  Examples of rubber latex include natural rubber latex, styrene / butadiene rubber latex, vinylpyridine / styrene / butadiene copolymer latex, acrylonitrile / butadiene rubber latex, chloroprene rubber latex, and the like. use. Among them, it is preferable to use vinylpyridine / styrene / butadiene copolymer latex alone or in combination. In the case of combined use, particularly excellent performance is exhibited when used in an amount of 1/3 or more of the total latex weight.

  The first treatment liquid contains the polyepoxide compound (A), the blocked polyisocyanate compound (B), and the rubber latex (C), and the blending weight ratio of each component (A), (B), (C) is (A). / [(A) + (B)] is preferably 0.05 to 0.9, and (C) / [(A) + (B)] is preferably 0.05 to 15. Furthermore, it is blended so that (A) / [(A) + (B)] is in the range of 0.1 to 0.5 and (C) / [(A) + (B)] is in the range of 1 to 10. Is preferred. Here, when (A) / [(A) + (B)] is out of the above range, the rubber adhesion rate to the fiber material tends to deteriorate and the adhesiveness tends to decrease, and (C) / [(A) + When (B)] is smaller than the above range, the treated fiber material becomes hard and tends to cause a decrease in fatigue resistance, and when larger than the above range, the adhesiveness tends to decrease.

  The first treatment liquid containing the polyepoxide compound, the blocked isocyanate compound, and the rubber latex is usually used as an emulsion, an aqueous dispersion, or an aqueous solution. To make an emulsion or aqueous dispersion, for example, as it is or after being dissolved in a small amount of a solvent, a known emulsifier such as sodium alkylbenzenesulfonate, dioctylsulfosuccinate sodium salt, nonylphenol ethylene oxide adduct, etc. What is necessary is just to emulsify or disperse using.

  The second treatment liquid used in the present invention mainly includes resorcin, formalin, and rubber latex. This treatment liquid is preferably composed of a resorcin / formalin precondensate generally used as an RFL adhesive for rubber / fiber and a rubber latex.

  The second treatment liquid is preferably a mixture of an RFL adhesive and a blocked isocyanate compound. The RFL adhesive has a molar ratio of resorcin to formaldehyde in the range of 1 / 0.1 to 1/8, preferably 1 / 0.5 to 1/5, more preferably 1/1 to 1/4. The preferred blending ratio of the resorcin / formalin initial condensate and the rubber latex varies depending on the addition ratio of the blocked polyisocyanate compound, but the initial condensate: rubber latex is 1: 1 to 1: A range of 15, especially 1: 3 to 1:12 is suitable. The blocked isocyanate compound is an addition compound of a polyisocyanate compound and a blocking agent similar to that used in the first treatment liquid. The addition rate of the blocked polyisocyanate compound is preferably 0.5 to 30% by weight with respect to RFL. The second treatment liquid is preferably treated at a total solid content concentration of 1 to 30% by weight, particularly 5 to 20% by weight.

  In order to adhere the first treatment liquid and the second treatment liquid to the fibers in the present invention, means such as application by contact with a roller or spraying from a nozzle or immersion in a solution can be employed. Moreover, the solid content adhesion amount of the adhesive composition to the fiber is preferably in the range of 0.1 to 10% by weight, preferably in the range of 0.3 to 7% by weight, more preferably 0 for each treatment liquid. It should be in the range of 5% to 3% by weight. In order to control the amount of solids adhered to the fibers, in addition to adjusting the concentration and viscosity of the treatment liquid, it is performed by means of squeezing with a pressure roller, scraping with a scrubber, etc., blowing off with air blowing, suction, and beater means. In order to increase the amount of adhesion, it may be adhered multiple times.

  In the treatment of the first treatment liquid and the second treatment liquid in the present invention, the fibers are treated using the treatment liquid, and then at 50 ° C. or more and 10 ° C. It is preferable to dry and heat-treat at a low temperature for 0.5 to 5.0 minutes. For example, when the fiber to be used is a polyester fiber, it is more preferable to dry and heat-treat at a temperature of 220 to 250 ° C. for 1 to 3 minutes. If the drying and heat treatment temperature is too low, the adhesion to rubbers tends to be insufficient, while if the temperature is too high, the synthetic fiber melts and fuses, or a significant reduction in strength occurs, making it unusable.

  Thus, the rubber reinforcing fiber obtained by the production method of the present invention has very little adhesive force to rubber, particularly heat deterioration. Furthermore, it is flexible and highly resistant to fatigue, and is optimal as a reinforcing fiber. This rubber reinforcing fiber is used for a fiber reinforced rubber fiber composite such as tires, belts and hoses, for example, and the resulting rubber fiber composite exhibits high quality properties with high adhesiveness. It is extremely useful as a rubber product.

Hereinafter, an example is given and the composition and effect of the present invention are explained in detail.
[Example 1]
A plain woven fabric of polyethylene terephthalate fibers of 1100 dtex / 192 filaments (basis weight = 250 g / m ² ) for 30 seconds in a mixed gas medium of 0.5% butadiene and 99% nitrogen under atmospheric pressure (101,000 Pa) Plasma treatment was performed with a pulsed electric field.

  Next, a polyepoxide compound, blocked polyisocyanate, and rubber latex are mixed at a ratio of 3.0 parts by weight, 13 parts by weight, and 84 parts by weight to form a first treatment liquid having a total solid concentration of 10.0% by weight, and plasma treatment. The plain woven fabric subjected to was immersed. Thereafter, it was dried at 130 ° C. for 2 minutes and subsequently heat treated at 240 ° C. for 1 minute.

  Next, in order to prepare the second treatment liquid, first, an initial condensate having a resorcin / formalin (R / F) molar ratio of 1 / 0.6 and a solid content concentration of 65% by weight was dissolved under alkaline conditions. A weight% aqueous solution was obtained. 57 parts by weight of this was added to 420 parts by weight of a 9% aqueous emulsion of vinylpyridine / styrene / butadiene copolymer latex, and 3 parts by weight of formalin and 33% by weight of acetoxime blocked diphenylmethane diisocyanate dispersion were added to this liquid. 13 weight part was added and it was set as the 2nd process liquid of 20 weight% of solid content concentration age | cure | ripened for 48 hours. The plain woven fabric subjected to the plasma treatment and the treatment with the first treatment liquid was immersed in the second treatment liquid, then dried at 150 ° C. for 2 minutes, and subsequently heat treated at 240 ° C. for 1 minute.

The obtained treated plain woven fabric is overlapped with an unvulcanized rubber containing carcass containing natural rubber as a main component, and vulcanized at 160 ° C. for 20 minutes as an initial condition at a pressing pressure of 500 N / cm ² . A bonded body of plain woven fabric and rubber was obtained. At this time, a release paper or film was previously sandwiched between the woven fabric and the rubber sheet to create a non-bonded portion of the plain woven fabric and rubber. Cut the plain woven fabric and the rubber bonded body into 2.54 cm (1 inch) width, hold the plain woven fabric and the plain woven fabric of the non-bonded part of the rubber with a jig, and 90 mm to the rubber sheet at 100 mm / min The result of the force required for peeling at a speed of N / 2.54 cm was defined as the initial adhesive force. Furthermore, the vulcanization time was changed to 160 ° C. and 60 minutes as heat resistant conditions, and the same measurement was performed to obtain heat resistant adhesive strength. The heat deterioration resistance was expressed in% as the heat-resistant maintenance ratio, which is the ratio of the heat-resistant adhesive force to the initial adhesive force. The results are shown in Table 1.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that the plasma treatment was not performed. The results are also shown in Table 1.

[Comparative Example 2]
The same operation as in Example 1 was performed except that the treatment with the first treatment liquid was not performed. The results are also shown in Table 1.

[Comparative Example 3]
The same operation as in Example 1 was performed except that the plasma treatment and the treatment with the first treatment liquid were not performed. The results are also shown in Table 1.

Claims (4)

  The fiber is plasma-treated in a medium containing an alkene and / or alkyne gas, and then a first treatment liquid containing a polyepoxide compound, a blocked isocyanate compound and a rubber latex, and a first treatment mainly comprising resorcin, formalin and rubber latex. A method for producing a fiber for reinforcing rubber, characterized by sequentially treating with two treatment liquids.   2. The method for producing a fiber for reinforcing rubber according to claim 1, wherein the fiber is a synthetic fiber.   The method for producing a fiber for reinforcing rubber according to claim 1 or 2, wherein the medium during the plasma treatment is mainly nitrogen.   The method for producing a rubber-reinforcing fiber according to any one of claims 1 to 3, wherein the concentration of alkenes and / or alkynes during plasma treatment is 0.1 to 15% by volume.