JP7448342B2 - Composite cord for rubber reinforcement and power transmission belt using the same - Google Patents

Description

The present invention relates to a rubber reinforcing composite cord used for reinforcing rubber products such as rubber belts and tires.

2. Description of the Related Art In order to improve the strength and durability of rubber products such as rubber belts and rubber tires, it is common practice to embed reinforcing fibers into rubber. Conventionally, glass fibers, polyvinyl alcohol fibers, polyester fibers, nylon, polyamide fibers, carbon fibers, and polyparaphenylenebenzooxal fibers have been widely used as the reinforcing fibers. Among these, polyamide fibers, especially aramid fibers, are suitable and widely used.

These fibers have many advantages and are used, for example, to reinforce power transmission belts and high-performance tires. However, with these cords, it is difficult to simultaneously satisfy the moldability of the rubber composition due to elongation during molding and the rigidity during use of the rubber molded product.

As an improvement measure, for example, Patent Document 1 (Japanese Unexamined Patent Publication No. 2008-100365) describes a composite cord made of para-aromatic polyamide fiber and aliphatic polyamide fiber as a composite cord that has elongation in a low load region. Disclosed. In this composite cord, the proportion of para-type aromatic polyamide fibers in the composite cord is not high, and the proportion of low-strength, low-modulus aliphatic polyamide fibers is large.As a result, the overall cord diameter of the composite cord is large. Not only that, but the cord as a whole becomes thicker, including the high-modulus fibers, and when bent at the same radius of curvature, the cord becomes more strained, resulting in a problem of lower bending fatigue durability.

In addition, aromatic polyamide fibers have excellent properties such as high strength, high modulus of elasticity, dimensional stability, heat resistance, and chemical resistance. Taking advantage of these properties, aromatic polyamide fibers can be used as rubber reinforcing fibers for applications such as tires, hoses, and belts. However, the surface of aromatic polyamide fibers is often relatively inert, and the adhesion to the matrix rubber is insufficient as it is, and the characteristics of aromatic polyamide fibers cannot be fully demonstrated. The problem is that it cannot be done.

Japanese Patent Application Publication No. 2008-100365

The purpose of the present invention is to solve the above-mentioned problems of the prior art, and to provide a composite cord for rubber reinforcement that combines tensile strength, elongation at low loads, high modulus of elasticity at high loads, fatigue resistance, and adhesive properties. Our goal is to provide the following.

The present invention is a composite cord containing high-strength, high-modulus fibers and low-modulus fibers, in which the high-strength, high-modulus fibers are included as a fiber bundle (A) of high-strength, high-modulus fibers, and the high-strength, high-modulus fibers are The elastic modulus fiber has a strength of 10 cN/dtex or more and an initial tensile resistance of 300 cN/dtex or more, and the low elastic modulus fiber has a strength of 9 cN/dtex or less and an initial tensile resistance of 100 cN/dtex or less, and the composite This is a composite cord for rubber reinforcement, characterized in that the weight ratio of high-strength, high-modulus fibers and low-modulus fibers contained in the cord is 99:1 to 88:12.

According to the present invention, the above-mentioned problems of the prior art are solved, and a composite cord for rubber reinforcement is provided that has tensile strength, elongation at low loads, high modulus of elasticity at high loads, fatigue resistance, and adhesive properties. can be provided.

[High strength, high modulus fiber]
As the high-strength, high-modulus fibers of the fiber bundle (A), fibers with a strength of 10 cN/dtex or more and an initial tensile resistance of 300 cN/dtex or more are used. Examples of high-strength, high-modulus fibers that satisfy this condition include glass fibers, aromatic polyamide fibers, carbon fibers, polyparaphenylene benzoxal fibers, aromatic polyester fibers, and ultra-high molecular weight polyethylene fibers. Among these, aromatic polyamide fibers are preferred.

As the aromatic polyamide fiber itself, a conventionally known one can be used, and it can be manufactured by a conventionally known method. For example, they are described in JP-A-49-100322, JP-A-47-10863, JP-A-58-144152, and JP-A-4-65513.

Among aromatic polyamide fibers, para-type aromatic polyamide fibers are preferred because they have excellent heat resistance and strength. Para-type aromatic polyamide fibers are polyamide fibers in which the extended chain bonds of the aromatic polyamide are coaxial or parallel and oriented in opposite directions. Specifically, polyparaphenylene terephthalamide fibers (for example, "Twaron" manufactured by Teijin Aramid B.V.) and copolymerized aromatic polyamide fibers such as copolyparaphenylene, 3,4'-oxydiphenylene, Terephthalamide fiber (for example, "Technora" manufactured by Teijin Ltd.) can be exemplified.

In particular, copolyparaphenylene/3,4'-oxydiphenylene/terephthalamide fiber (eg, "Technora" manufactured by Teijin Ltd.), which is a copolymerized aromatic polyamide fiber, is preferable because it has excellent bending fatigue durability.

[Low modulus fiber]
As the low elastic modulus fiber, a fiber having a strength of 9 cN/dtex or less and an initial tensile resistance of 100 cN/dtex or less is used. Examples of low modulus fibers that satisfy this condition include polyurethane fibers, aliphatic polyamide fibers known as nylon 6, nylon 66, and nylon 46, polyester fibers known as polyethylene terephthalate and polytrimethylene terephthalate, and polyester fibers known as vinylon. Examples include polyvinylic alcohol fibers and rayon fibers. Among these, polyurethane fibers with a lower modulus of elasticity and elongation at break of 30% or more and polyethylene terephthalate fibers with a low degree of polymerization are preferred because they are easy to handle in the twisting process and can easily obtain elongation at low loads. . More preferably, fibers with a breaking elongation of 100% or more are used.

[Fiber bundle, monofilament]
In the present invention, high-strength, high-modulus fibers are used as the fiber bundle (A). The low modulus fibers are preferably used as fiber bundles (B) and/or monofilaments (C). That is, the low modulus fibers are preferably included as a fiber bundle (B) of low modulus fibers or a monofilament (C) of low modulus fibers.

The weight ratio of high-strength, high-modulus fibers to low-modulus fibers contained in the composite cord of the present invention is 99:1 to 88:12 (high-strength, high-modulus fibers: low-modulus fibers). If the weight ratio of the high-strength, high-modulus fibers is less than 88%, the strength and modulus of elasticity in the high elongation region will be low. On the other hand, if the weight ratio of the high-strength, high-modulus fibers exceeds 99%, the modulus of elasticity in the low elongation region will be high, resulting in poor elongation during vulcanization with rubber, resulting in a composite cord with poor moldability.

[Twisted thread]
From the viewpoint of obtaining good tensile strength, elongation at low loads, high elastic modulus at high loads, and fatigue resistance, the fiber bundle of high strength and high elastic modulus fibers is preferably used as twisted yarn. As the twisting increases, the orientation of the single fibers becomes more inclined, so the initial tensile strength decreases, but on the other hand, the stress applied to the single fibers during bending is dispersed, improving the bending fatigue resistance.

It is preferable that the low elastic modulus fibers be twisted or used with a small number of twists.

When both high-strength, high-modulus fibers and low-modulus fibers are used as a fiber bundle, the raw yarns may be doubled or twisted to obtain a fiber bundle with a predetermined fineness.

When the present invention is a composite cord composed of a fiber bundle (A) of high-strength, high-modulus fibers, and a fiber bundle (B) and/or monofilament (C) of low-modulus fibers, in the S direction Alternatively, the fiber bundle (A), which is a strand of high-strength, high-modulus fibers that are first-twisted in the Z direction, and the fiber bundle (B), which is a low-modulus fiber, are twisted in the direction opposite to the first-twisting direction of the high-strength, high-modulus fibers. Preferably, it is a composite cord that is ply-twisted in the direction.

In this case, during elongation, the fibers with a low elastic modulus are first elongated more preferentially, exhibiting a low elastic modulus, and from the middle, the stress burden on the fibers with a high elastic modulus increases, creating an ideal machine that exhibits a high elastic modulus. A composite code having physical properties can be obtained.

In the present invention, aromatic polyamide fibers are used as high-strength, high-modulus fibers, and the twist modulus (TM1) of the first twist (twist 1) of the fiber bundle (A) of the high-strength, high-modulus fibers, and the high-strength, high-modulus fibers are The twist coefficient (TM2) of the combined twist (twist 2) of the fiber bundle (A) of the fiber and the fiber bundle (B) of the low elastic modulus fiber and/or the monofilament (C) is expressed by the following formulas (1) to (3). It is preferable to satisfy all of the following. When this condition is satisfied, ideal tensile properties, single fiber orientation, and good fatigue resistance can be obtained.
2.0≦TM1≦6.0 (1)
1.0≦TM2≦5.0 (2)
1.0≦｜TM2-TM1｜≦5.0 (3)
The fiber bundle (B) of low elastic modulus fibers preferably has a twist coefficient of less than 2.0 in the first twist.

However, the twist coefficient (TM) is defined by the following formula. TM represents the twist coefficient, T represents the number of twists (times/m), and D represents the total fineness (tex) of the yarn.
TM=T×√D/1055
The above formula is a calculation formula generally used for cotton spun yarn, K=t/√N (K is the twist coefficient, t is the number of twists t/inch, and N is the cotton count). The specific gravity is changed to the specific gravity of aromatic polyamide fiber, and the cotton count is converted to fineness (tex).

When ply-twisting a fiber bundle (A) of high-strength, high-modulus fibers and a fiber bundle (B) and/or monofilament (C) of low-modulus fibers, each fiber bundle or monofilament is twisted one by one. A fiber bundle or monofilament may be used in combination, or a plurality of fiber bundles or monofilament may be twisted together.

When using a fiber bundle of aromatic polyamide resin as the high-strength, high-modulus fiber, it is preferable to impregnate the aromatic polyamide fiber bundle with a resin adhesive containing latex such as resorcinol formalin latex resin. The method for impregnating the resin adhesive containing latex may be carried out after the fiber bundle is twisted, or the fiber bundle may be twisted after being impregnated with the resin adhesive containing latex.

Latex-containing resin adhesives may be used in combination with phenol/aldehyde resin, maleimide-modified polybutadiene, or urethane-modified polybutadiene as an alternative to resorcinol/formalin for the purpose of improving the working environment, but the adhesive properties at high temperatures etc. From this viewpoint, resorcinol/formalin/latex resin is preferably used.

In a preferred embodiment of the composite cord of the present invention, the surface of the high-strength, high-modulus fibers is first treated with an epoxy compound, and then the single fibers are treated with resorcinol formalin latex without substantially intentionally twisting them. The fiber bundle is impregnated with resin by immersion treatment in a solution containing resin. Thereafter, a fiber bundle (A), which is a first-twisted yarn obtained by subjecting high-strength, high-modulus fibers to first-twisting, is prepared. Furthermore, for low elastic modulus fibers, a fiber bundle (B) is prepared by performing an epoxy compound treatment and a treatment with a resorcinol/formalin/latex resin after being untwisted or after being pre-twisted. Next, the fiber bundle (A) and the fiber bundle (B) are twisted together to form a composite cord. Thereafter, an adhesive treatment agent containing a rubber component and a crosslinking agent as constituent components may be applied as an overcoat.

[Epoxy compound]
High-strength, high-modulus fibers such as para-type aromatic polyamide fibers generally have inert surfaces and are difficult to adhere to other substances. Therefore, in the present invention, when aromatic polyamide resin is used as the high-strength, high-modulus fiber, it is preferable to use a single fiber of the aromatic polyamide fiber after surface treatment with an epoxy compound in order to obtain sufficient adhesiveness. The surface treatment with an epoxy compound may be performed after twisting the fiber bundle, or the surface treatment with an epoxy compound may be followed by twisting the fiber bundle. This surface treatment can improve the chemical affinity between the aromatic polyamide fiber and the resorcinol/formalin/latex resin.

The amount of solid content of the epoxy compound attached to the single fiber of the aromatic polyamide fiber is preferably 0.05 to 5.0% by weight, more preferably 0.2 to 2.0% by weight, based on the weight of the single fiber. be. If the amount of adhesion is less than this, the epoxy resin layer formed on the surface of the single yarn will not be sufficient, and the adhesion between single yarns of aromatic polyamide fibers and the adhesion between single yarns and resorcinol, formalin, and latex resin will be affected. It is difficult to obtain. On the other hand, if the amount of adhesion is greater than this, the epoxy resin will cause the single yarns to be strongly bundled together, resulting in the composite cord becoming hard and having poor bending fatigue resistance, which is not preferable.

Examples of epoxy compounds used for surface treatment include reaction products of polyhydric alcohols such as ethylene glycol, glycerol, sorbitol, pentaerythritol, and polyethylene glycol with halogen-containing epoxides such as epichlorohydrin, resorcinol, and pis(4- Polyepoxide compounds obtained by oxidizing unsaturated compounds with peracetic acid, hydrogen peroxide, etc., reaction products of polyhydric phenols such as hydroxyphenyl) dimethylmethane, phenol/formaldehyde resins, and resorcinol/formaldehyde resins with the halogen-containing epoxides. , namely, 3,4-epoxycyclohexene epoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexenecarboxylate, and bis(3,4-epoxy-6-methyl-cyclohexylmethyl)adibate.

Among these, a reaction product of a polyhydric alcohol and epichlorohydrin is preferred, and a compound produced by a polyepoxide compound such as a polyglycidyl ether compound of a polyhydric alcohol and a curing agent is also preferred. When a polyepoxide compound is used, an emulsifying agent such as sodium alkylbenzene sulfonate or sodium dioctyl sulfosuccinate may be used to form an emulsion.

The polyepoxide compound is combined with amine-based or imidazole-based curing agents, blocked polyisocyanate, which is an addition compound of polyisocyanate and a blocking agent such as oxime, phenol, or caprolactam, and ethylene urea, which is a reaction compound with ethyleneimine. You may.

When using a polyepoxy compound, when the weight of the polyepoxide compound is P parts by weight and the weight of the curing agent, blocked polyisocyanate and ethylene urea is Q parts by weight, P/(P+Q) is 0.05 to 0.9. It is preferable that Within this range, particularly good adhesiveness can be obtained.

When using polyurethane fibers or polyester fibers as the low modulus fibers, it is preferable to subject the fibers to surface treatment with an epoxy compound in the same way as aromatic polyamide fibers.

When using aliphatic polyamide fibers, polyvinyl alcohol fibers, or rayon fibers as low modulus fibers, these fibers have excellent adhesion to resorcinol, formalin, and latex resins, so treatment with epoxy compounds is not recommended. unnecessary.

[Resorcin, formalin, latex resin]
The rubber reinforcing composite cord of the present invention preferably contains a resin adhesive containing latex. The weight of the resin adhesive is preferably 5 to 25% by weight, more preferably 5 to 15% by weight, based on the total weight of the fibers, in order to obtain excellent adhesive strength. When the rubber reinforcing composite cord is composed of fiber bundles (A), fiber bundles (B) and/or monofilaments (C), the amount is 5 to 25% by weight, more preferably 5 to 25% by weight based on the total weight of these. It is 15% by weight.

As the resin adhesive containing latex, resorcinol formalin latex resin is preferable. The molar ratio of resorcinol and formaldehyde in the resorcinol formalin latex resin is preferably 1:0.6 to 1:8, more preferably 1:0.8 to 1:6. If the amount of formaldehyde is less than this range, the crosslinking density of the resorcinol/formalin condensate will decrease and the molecular weight will decrease, resulting in a decrease in the cohesive force of the resin layer, resulting in a decrease in adhesion and poor bending fatigue resistance. This is not preferable as there is a risk of the decrease. On the other hand, if the amount of formaldehyde is greater than this range, the resorcinol/formalin condensate will become hard due to the increase in crosslinking density, and the compatibilization of the resorcinol/formalin/latex resin and the rubber will be inhibited during co-vulcanization with the adherend rubber. This is not preferable since it tends to reduce adhesiveness.

The blending ratio of resorcinol/formalin and rubber latex in the resorcinol/formalin/latex resin is preferably 1:3 to 1:16, more preferably 1:4 as a solid weight ratio of resorcin/formalin: rubber latex. ~1:10. If the ratio of rubber latex is less than this range, the adhesion strength tends to decrease due to the small amount of co-vulcanized components with rubber, which is undesirable.On the other hand, if the ratio of rubber latex is more than this range, it may not be sufficient as an adhesive film. Since strength cannot be obtained, adhesive strength and durability tend to decrease, and the adhesiveness of the adhesive-treated composite cord increases significantly, resulting in problems such as cam-up and handling during the adhesive processing process and belt molding process. This is not preferable since it may reduce the permeability.

As the resorcin, a pre-oligomerized resorcin-formalin initial condensate or a polynuclear chlorophenol resorcin-formalin initial condensate obtained by oligomerizing chlorophenol and resorcin with formalin may be used alone or in combination as necessary. .

Examples of the rubber latex include hydrogenated acrylonitrile-butadiene rubber latex, acrylonitrile-butadiene latex, isoprene rubber latex, urethane rubber latex, styrene-butadiene rubber latex, vinylpyridine-styrene-butadiene rubber latex, chloroprene rubber latex, butadiene rubber latex, An example is chlorosulfonated polyethylene latex, which can be used alone or in combination. Vinylpyridine-styrene-butadiene rubber latex is preferred as the rubber latex because it has a high affinity with the epoxy compound on the surface of the single yarn of the composite cord and can increase the strength of the resin layer.

A crosslinking agent may be used in combination with the resorcinol/formalin/latex resin. Examples of crosslinking agents include amines, ethylene urea, and blocked isocyanate compounds. Among these, blocked isocyanate compounds are preferred because the treatment agent has good stability over time and good interaction with the pretreatment agent. Examples of the blocked isocyanate compound include dimethyl pyrazole block, methyl ethyl ketone oxime block, and caprolactam block blocked isocyanate. These may be used in combination of two or more types.

When a crosslinking agent is used, the amount added is, for example, 0.5 to 40% by weight, preferably 10 to 30% by weight, based on the total weight of the resorcinol/formalin/rubber latex resin. Increasing the amount added usually improves adhesive strength, but if the amount added is too large, the compatibility of the adhesive with rubber tends to decrease, and the adhesive strength with rubber tends to decrease, so use within this range. is preferred.

For high-strength, high-modulus fibers, this resorcinol-formalin-rubber latex resin treatment is preferably carried out after the surface of the high-strength, high-modulus fibers has been treated with an epoxy compound.

[Physical properties]
The composite cord for rubber reinforcement of the present invention has a strength at break of 10.0 cN/dtex or more, an elongation at break of 5 to 8%, a load at 2% elongation of 4 cN/dtex or less, and a 5% elongation shows a load of 6 cN/dtex or more. Although it is a high-strength fiber cord with physical properties in this range, by keeping the load and elastic modulus low at low elongation of up to 2.0%, it has improved workability, especially with low elastic modulus rubber. Rubber products reinforced with the composite fiber cord of the present invention have excellent Dimensional stability can be ensured. The composite fiber cord of the present invention can simultaneously satisfy the moldability of the rubber composition due to stretching during molding and the rigidity during subsequent use of the rubber molded product.

[Rubber]
The composite cord for reinforcing rubber of the present invention is used for reinforcing rubber, and constitutes a rubber product together with rubber. Rubbers used include acrylic rubber, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, isoprene rubber, urethane rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM), chloroprene rubber, silicone rubber, and styrene rubber. Examples include butadiene rubber, polysulfide rubber, natural rubber, butadiene rubber, and fluororubber. Particularly preferred are ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM), and hydrogenated acrylonitrile-butadiene (H-NBR) rubber.

In addition to the main component rubber, these rubbers contain various vulcanizing agents and vulcanization accelerators, and in order to modify the material, they also contain inorganic fillers such as carbon black, silica, coumaron resin, phenolic resin, etc. Various additives such as organic fillers, softeners such as naphthenic oils, etc. may be included. A rubber product can be obtained by arranging the required number of composite cords for rubber reinforcement of the present invention, sandwiching them between rubber, and further pressurizing and heating in the above-mentioned vulcanization pot or the like to form the cord.

〔Production method〕
The rubber reinforcing composite cord of the present invention consists of a strand of high-strength, high-elastic modulus fibers pre-twisted in the S direction or the Z direction, and a fiber bundle or monofilament of low-elastic modulus fibers, under the high-strength, high-elastic modulus fibers. It can be manufactured by twisting the yarn in the opposite direction to the twisting direction to form a twisted yarn cord.

That is, the invention also provides a method for producing a composite cord for rubber reinforcement, in which strands of high-strength, high-modulus fibers pre-twisted in the S direction or Z direction and fiber bundles or monofilaments of low-modulus fibers are This is a method for manufacturing a composite cord for rubber reinforcement, which is characterized in that the fibers with high strength and high elastic modulus are twisted in a direction opposite to the direction in which they are first twisted to form a twisted yarn cord.

The composite cord is preferably impregnated with resorcinol, formalin, and latex resin. This impregnation treatment is carried out by contacting high-strength, high-modulus fibers or low-modulus fibers whose surface has been treated with an epoxy compound with a solution containing resorcinol, formalin, and latex resin, at a temperature of, for example, 100°C to 250°C for 60 to 60°C. This can be done by drying and heat treatment for 300 seconds. Preferred conditions are drying at a temperature of 100-180°C for 60-240 seconds, followed by heat treatment at a temperature of 200-245°C for 60-240 seconds.

The contact between the fibers and the resorcinol/formalin/latex resin during the impregnation treatment can be carried out, for example, by bringing the resorcin/formalin/latex resin or its solution into contact with the fibers with a roller, or by spraying the solution onto the fibers from a nozzle. Can be done.

In order to suppress the content of resorcinol/formalin/latex resin impregnated into the fiber bundle, means such as squeezing with a pressure roller, scraping with a scraper, blowing with air, suction, and a beater can be used. In order to increase the content, it may be attached to the fibers multiple times.

When para-type aromatic polyamide fibers are used, the fiber surface treatment with an epoxy compound can be carried out as follows. For example, a solution containing an epoxy compound is mixed with an oil agent during the spinning process of para-type aromatic polyamide fibers and attached to the single threads of the fiber, or after spinning of para-type aromatic polyamide fibers, a process separate from the spinning process is carried out. The emulsifier of the epoxy key is attached to the single fiber filament, and after attachment, it is heat-treated at a temperature of 100 to 250°C for 10 to 120 seconds.

When a polyepoxide compound is used as the epoxy compound, an emulsion containing the polyepoxide compound, a curing agent, blocked polyisocyanate, or ethylene urea is mixed with an oil agent during the spinning process of aromatic polyamide fibers to form single fibers. After the emulsifier is attached or after spinning the para-type aromatic polyamide fiber, the emulsifier is attached to the single yarn of the fiber in a process different from the spinning process, and after the emulsifier is attached, the emulsifier is heat-treated at a temperature of 100 to 250°C for 10 to 120 seconds. It is preferable.

The present invention will be explained below with reference to Examples. Note that evaluations in Examples of the present invention were performed using the following measurement method. Resorcinol formalin latex resin is sometimes abbreviated as RFL.
(1) Initial tensile resistance Copolyparaphenylene/3,4'-oxydiphenylene/terephthalamide fiber and polyethylene terephthalate fiber were measured according to JIS L1017. The polyurethane fibers were measured under the same conditions as JIS L1017, except that the gripping interval was 5 cm and the pulling speed was 6 cm/min.
(2) Cord fineness Cord fineness (weight) was measured according to JIS L1017.
(3) Cord strength and cord strength Cord strength was measured according to JIS L1017. The strength was calculated from the strength and cord weight by measuring the weight of the cord including the amount of resin adhesion according to JIS L1017.
(4) Breaking elongation (cutting elongation), load at 2.0% elongation, load at 5.0% elongation Measured by conducting a tensile test in accordance with JIS L1017 on composite cords containing adhesive treatment agents. and calculated. The elongation at break of the composite cord is the elongation at break of the high-strength, high-modulus fibers, and the elongation of the low-modulus fibers that remain unbroken after the breakage of the high-strength, high-modulus fibers is not considered. .
(5) Strength after bending fatigue, strength retention rate after bending fatigue A composite cord containing resorcinol, formalin, and latex resin was loaded with a load of 1.6 cN/dtex, attached to a roller with a diameter of 10 mmφ, and made to reciprocate at 100 rpm. After bending was repeated ,000 times, the composite cord was taken out and its residual strength was measured to determine its strength after bending fatigue and its strength retention rate.

[Preparation of resorcinol/formalin/latex resin treatment agent (RFL agent)]
Add 19.8 g of a resorcinol-formalin initial condensate (Sumikanol 700S, manufactured by Sumitomo Chemical Co., Ltd., concentration 65% by weight) with a molar ratio of resorcin/formalin (R/F) of 1/0.6 to 154.5 g of water. Vinylpyridine-styrene-butadiene rubber latex (Nipole 2518FS, manufactured by Nippon Zeon Co., Ltd., concentration 40% by weight) was dissolved in an alkaline aqueous solution containing 5.0 g of 10% caustic soda water and 19.9 g of 20% ammonia water. 415 g and 368.9 g of water were added. To this solution, 16.8 g of 37% formalin water and methyl ethyl ketone oxime blocked diphenylmethane diisocyanate (DM6400, manufactured by Meisei Chemical Industry Co., Ltd., concentration 42% by weight) were added, and the mixture was aged at 20°C for 48 hours to achieve a solid content concentration of 20%. An aqueous dispersion (resorcinol/formalin/latex resin treatment agent (RFL agent)) containing % by weight of resorcinol/formalin/latex resin was prepared.

[Epoxy treatment of polyurethane fibers and polyethylene terephthalate fibers]
17.5 g of glycerol polyglycidyl ether ("Denacol EX-313" manufactured by Nagase ChemteX Co., Ltd.) and dioctyl sulfosuccinate sodium salt ("Neocol SW-30" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a surfactant.14. The surface was treated with an epoxy solution containing 5 g of piperazine, 4 g of piperazine, and 656.2 g of water with a solid content concentration of 3.7% by weight, and after drying, the epoxy treatment was carried out by winding up.

[Example 1]
About pre-epoxy-treated copolyparaphenylene 3,4'-oxydiphenylene terephthalamide fiber (Teijin Ltd. Technora T202 1670dtex, 1000 filament, initial tensile resistance 630cN/dtex) as high-strength, high-modulus fiber After immersing in the above resorcinol formalin latex resin using a computer processor processing machine (CA Ritzler dip cord processing machine), drying at 130 ° C. for 2 minutes, followed by heat treatment at 235 ° C. for 1 minute, A copolyparaphenylene/3,4'-oxydiphenylene/terephthalamide fiber coated with an RFL agent was obtained. Next, twisting was performed in the S direction with a twist coefficient of 2.4 (200 times/m) to obtain a fiber bundle (A) consisting of a ply-twisted yarn of copolyparaphenylene/3,4'-oxydiphenylene/terephthalamide fibers. .

In addition, eight polyurethane fibers (Roica 22 dtex monofilament manufactured by Asahi Kasei Corporation, initial tensile resistance 1.5 cN/dtex) were aligned as low elastic modulus fibers, and after the above-mentioned epoxy treatment was applied, the above-mentioned resorcinol - Formalin latex resin treatment was carried out to obtain a fiber bundle (B) without twisting.

Thereafter, two fiber bundles (A) made of the ply-twisted copolyparaphenylene/3,4'-oxydiphenylene/terephthalamide fibers obtained above and one fiber bundle (B) of polyurethane fibers were then combined. At the same time, a composite cord was obtained by performing ply twisting in the Z direction with a twist coefficient of 4.6 (260 times/m).
The evaluation results of the obtained composite code are summarized in Table 1.

[Example 2]
Instead of eight polyurethane monofilaments, three polyethylene terephthalate fibers (Teitoron T300SB SD 84 dtex, 36 filaments, initial tensile resistance 74 cN/dtex, manufactured by Teijin Ltd.) were arranged as low elastic modulus fibers, and the above-mentioned epoxy After treatment and resorcinol/formalin/latex resin treatment, the fibers were first twisted in the S direction with a twist coefficient of 1.4 (300 times/m) and used as a fiber bundle (B). In addition, two fiber bundles (A) made of the same copolyparaphenylene/3,4'-oxydiphenylene/terephthalamide fibers as in Example 1 and a fiber bundle (B) of the above-mentioned polyethylene terephthalate fiber were prepared. A composite cord was obtained in the same manner as in Example 1 except that a ply-twisted yarn with a twist coefficient of 4.6 (255 times/m) was applied in the Z direction.
The evaluation results of the obtained composite code are summarized in Table 1.

[Comparative example 1]
As a low elastic modulus fiber, one polyethylene terephthalate fiber (Teitoron P903BZ 560 dtex, 96 filaments, initial tensile resistance 83 cN/dtex, manufactured by Teijin Ltd.) was used instead of eight monofilaments of polyurethane fiber, and the above-mentioned epoxy treatment and After being treated with resorcinol/formalin/latex resin, it was pre-twisted in the Z direction at a twist coefficient of 1.8 (250 times/m) and used as a fiber bundle (B). In addition, two fiber bundles (A) made of the same copolyparaphenylene/3,4'-oxydiphenylene/terephthalamide fiber as in Example 1 and a fiber bundle (B) of the above-mentioned polyethylene terephthalate fiber were prepared. A composite cord was obtained in the same manner as in Example 1 except that a ply-twisted yarn with a twist coefficient of 4.6 (245 times/m) was applied in the Z direction.
The evaluation results of the obtained composite code are summarized in Table 1.

The rubber reinforcing composite cord of the present invention can be suitably used as a core wire of a power transmission belt or a tire cord. In particular, it is preferably used for V-ribbed belts, etc., in which the rib surface is covered with fabric, which is manufactured by a molding method that is difficult to form.

In addition, by improving durability and breaking strength, we can expect a longer service life for the power transmission belt, and by making the power transmission belt smaller and narrower, we can expect to save energy by reducing weight and improving transmission efficiency.

Claims (3)

A composite cord comprising high-strength, high-modulus fibers and low-modulus fibers,
The high-strength, high-modulus fibers are included as a fiber bundle (A) of high-strength, high-modulus fibers,
The high-strength, high-modulus fibers have a strength of 10 cN/dtex or more and an initial tensile resistance of 300 cN/dtex or more, and the low-modulus fibers are fiber bundles of polyethylene terephthalate fibers or polyurethane fibers, and the strength is 9 cN/dtex. and the initial tensile resistance is 100 cN/dtex or less, and the weight ratio of high strength, high elastic modulus fibers and low elastic modulus fibers included in the composite cord is 99:1 to 88:12, and The composite cord contains a resin adhesive containing latex, and the weight of the resin adhesive is 5 to 25% by weight based on the total weight of the fibers, and is characterized in that it is used for a V-ribbed belt. Composite code for. The composite cord for rubber reinforcement according to claim 1, wherein the low elastic modulus fibers are included as a fiber bundle (B) of low elastic modulus fibers or a monofilament (C) of low elastic modulus fibers. The fiber bundle (A) is a twisted yarn of high-strength, high-elastic modulus fibers that are first twisted in the S direction or the Z direction, and this fiber bundle (A) and the fiber bundle (B) of low-elastic modulus fibers are The composite cord for rubber reinforcement according to claim 2, wherein the high elastic modulus fibers are first twisted in a direction opposite to the first twisting direction.