JP2021014663A - Aramid fiber cord for rubber hose reinforcement and fiber reinforced rubber hose - Google Patents

Abstract

To provide an aramid fiber cord that can be used as a reinforcement fiber of a low expansive rubber hose suitable as a hose for vehicles and in which treatment agent scum of a cord surface layer was prevented from falling during braiding while having excellent adhesiveness with a rubber matrix.SOLUTION: An aramid fiber cord for rubber hose reinforcement that is used as a fiber reinforcement layer having a fiber reinforcement layer between an inner rubber layer and an outer rubber layer, the aramid fiber cord for rubber hose reinforcement is manufactured in such a manner as that twisted aramid fiber is treated first with a first treatment agent containing a thermally reactive oligomer component made of a polyepoxide compound and a blocked polyisocyanate compound, then, is treated with a second treatment agent containing resorcin formalin rubber latex, a blocked polyisocyanate compound and a chlorophenol compound.SELECTED DRAWING: None

Description

The present invention relates to an aramid fiber cord for reinforcing a rubber hose.

Aramid fiber is used as a fiber cord for reinforcing a rubber hose because it has excellent properties such as high heat resistance, high strength, high Young's modulus and low shrinkage. In a fiber reinforced rubber hose having a reinforcing layer made of aramid fibers, a reinforcing layer made of aramid fibers is arranged on an inner rubber layer arranged in the innermost layer, and an interlayer rubber layer is arranged on the reinforcing layer. A reinforcing layer made of aramid fibers is disposed on the interlayer rubber layer, and an outer surface rubber layer is further disposed on the reinforcing layer. Generally, the inner rubber layer and the outer rubber layer are made of ethylene propylene rubber. The aramid fibers used for the reinforcing layer consist of polyparaphenylene terephthalamide or copolyparaphenylene, 3,4'oxydiphenylene, and terephthalamide, and these aramid fibers form a blade structure or a spiral structure to form the reinforcing layer. ..

Vehicle hoses, which are one of the uses of rubber hoses, have a small volume expansion amount in a wide temperature range from low temperature to high temperature in order to ensure the sensitive operation of the braking system, that is, they have good expansion resistance. (Having low expansion) is indispensable. A hose having low expansion property has been developed for use as a vehicle hose, and a fiber cord having a high elastic modulus has been applied to a reinforcing layer of the hose.

Japanese Patent No. 4456825 JP-A-2005-54304

There is a problem that the treatment agent scum on the surface layer of the fiber cord falls off when the fiber cord is braided, and if the scum is significantly deposited, the scum will peel off and be mixed in the fiber cord, and the quality of the obtained fiber reinforced rubber hose will be improved. descend.

An object of the present invention is that it can be used as a reinforcing fiber of a low-expansion fiber-reinforced rubber hose suitable as a vehicle hose, and is braided in a fiber-reinforced rubber hose manufacturing process while having good adhesion to a rubber matrix. An object of the present invention is to provide an aramid fiber cord for reinforcing a rubber hose in which the treatment agent scum on the surface layer of the fiber cord is prevented from falling off in a braiding process in which the fiber cord is scraped by the machine guide.

That is, the present invention is a rubber hose reinforcing aramid fiber cord used as a fiber reinforcing layer of a fiber reinforced rubber hose having a fiber reinforcing layer between an inner layer rubber layer and an outer layer rubber layer, and first, twisted aramid fibers are used. Treat with a first treatment agent containing a polyepoxide compound and a blocked polyisocyanate compound, then with a second treatment agent containing resorcin formalin rubber latex (RFL), a blocked polyisocyanate compound and a chlorophenol compound. It is an aramid fiber cord for reinforcing rubber hoses, which is characterized by being manufactured by.

The present invention is also a method for producing a aramid fiber cord for reinforcing a rubber hose, which is used as a fiber reinforcing layer of a fiber reinforced rubber hose having a fiber reinforcing layer between an inner layer rubber layer and an outer layer rubber layer, and is a twisted aramid fiber. The cord is first treated with a first treatment agent containing a polyepoxide compound and a blocked polyisocyanate compound, and then with a second treatment agent containing a resorcin formalin rubber latex, a blocked polyisocyanate compound and a chlorophenol compound. This is a method for manufacturing an aramid fiber cord for reinforcing a rubber hose, which is characterized by the above.

According to the present invention, it can be used as a reinforcing fiber of a low-expansion fiber-reinforced rubber hose suitable as a vehicle hose, and is braided in a fiber-reinforced rubber hose manufacturing process while having good adhesion to a rubber matrix. It is possible to provide an aramid fiber cord for reinforcing a rubber hose in which the treatment agent scum on the surface layer of the fiber cord is prevented from falling off in the braiding process in which the fiber cord is scraped by the machine guide.

Hereinafter, the present invention will be described in detail.

[Aramid fiber cord]
Para-aromatic polyamide is used as the aramid of the aramid fiber cord, and polyparaphenylene terephthalamide or copolyparaphenylene 3,4'oxydiphenylene terephthalamide is preferably used. As the aramid fiber cord, aramid fibers, for example, twisted filament yarns and spun yarns can be used.

Fibers of polyparaphenylene terephthalamide can be obtained on the market, for example, as Twaron (registered trademark) manufactured by Teijin Limited, and fibers of copolyparaphenylene, 3,4'oxydiphenylene, and terephthalamide can be obtained, for example. It can be obtained on the market as Technora (registered trademark) manufactured by Teijin Limited.

[Treatment with the first treatment agent]
In the present invention, the above-mentioned aramid fiber cord is first treated with the first treatment agent. This treatment is a treatment for adhering the solid content component of the first treatment agent to the aramid fiber cord. This can be done by dipping or applying the first treatment agent to the aramid fiber cord. The coating may be performed by, for example, a roller or by spraying.

The first treatment agent is an aqueous dispersion containing a polyepoxide compound and a blocked polyisocyanate compound. In this treatment agent, the blocking component of the blocked polyisocyanate compound is liberated by heating to produce an active polyisocyanate compound.

The concentration of the polyepoxide compound in the aqueous dispersion, which is the first treatment agent, is, for example, 10% by weight or less, preferably 0.5 to 8% by weight. This range is preferable from the viewpoint of handleability.

The concentration of the blocked polyisocyanate compound in the aqueous dispersion, which is the first treatment agent, is, for example, 10 to 60% by weight, preferably 20 to 50% by weight. This range is preferable in terms of adhesive strength.

From the viewpoint of adhesiveness and handleability, the blending ratio of the polyepoxide compound and the broken polyisocyanate compound in the first treatment agent is, for example, 1 to 10 parts by weight of the broken polyisocyanate compound with respect to 1 part by weight of the polyepoxide compound. It is preferably 2 to 9 parts by weight.

[Treatment with a second treatment agent]
The treatment with the second treatment agent is a treatment for adhering the solid content component of the second treatment agent to the aramid fiber cord. This is performed on the aramid fiber cord that has been once dried and heat-treated after the treatment with the first treatment agent, that is, the treatment for adhering the solid component portion of the first treatment agent to the aramid fiber cord. .. This treatment can be performed by immersing or applying a second treatment agent to the aramid fiber cord. The coating may be performed by, for example, a roller or by spraying.

The second treatment agent is an aqueous dispersion containing resorcin, formalin, rubber latex (RFL), a blocked polyisocyanate compound, and a chlorophenol compound as solid content components. The total concentration of the solid content of the aqueous dispersion, which is the second treatment agent, is, for example, 1.4 to 40% by weight, preferably 3 to 25% by weight. If it is less than 1.4% by weight, the adhesive force is not exhibited, and if it exceeds 40% by weight, the treatment agent gels and cannot be treated in the treatment step.

The content of resorcin, formalin, and rubber latex in the aqueous dispersion, which is the second treatment agent, is, for example, 1 to 15% by weight, preferably 2 to 12% by weight. If it is less than 1% by weight, sufficient rubber adhesive strength cannot be obtained, and if it exceeds 12% by weight, the scum will drop off significantly during cord braiding.

The content of the blocked polyisocyanate compound in the aqueous dispersion, which is the second treatment agent, is, for example, 0.2 to 20% by weight, preferably 0.5 to 10% by weight. If it is less than 0.2% by weight, the adhesive strength is likely to be insufficient, and if it exceeds 20% by weight, scum is likely to occur.

The content of the chlorophenol compound in the aqueous dispersion, which is the second treatment agent, is, for example, 0.2 to 20% by weight, preferably 0.5 to 10% by weight. If it is less than 0.2% by weight, the adhesive strength tends to be insufficient, and if it exceeds 20% by weight, the cost increases.

[Polyepoxide compound in the first treatment agent]
The polyepoxide compound contained in the first treatment agent in the present invention is a compound containing at least two or more epoxy groups in one molecule in an amount of 0.2 g equivalent or more per 100 g of the compound. This polyepoxide compound is a reaction product of polyhydric alcohols such as ethylene glycol, glycerol, sorbitol, pentaerythritol and polyethylene glycol with halogen-containing epoxides such as shrimp chlorohydrin, resorcin bis (4-hydroxyphenyl) dimethylmethane. , A reaction product of polyhydric phenols such as phenol / formaldehyde resin and resorcin / formaldehyde resin with the halogen-containing epoxides, and a polyepoxide compound obtained by oxidizing an unsaturated compound with peracetic acid or hydrogen peroxide. ..

Specific examples of such a polyepoxide compound include 3,4-epoxycyclohexene epoxide, 3,4-epoxycyclohexene methyl, 3,4-epoxycyclohexene carpoxylate, and bis (to 3,4-epoxy-6-methyl-cyclo). Xylmethyl) epoxide and the like. In particular, a reaction product of a polyhydric alcohol and shrimp chlorohydrin, that is, a polyglycidyl ether compound of the polyhydric alcohol is preferable because it exhibits excellent performance.

The polyepoxide compound is used as an aqueous dispersion (emulsified solution) or a solution. To make an aqueous dispersion or solution, the polyepoxide compound is used as it is or, if necessary, dissolved in a small amount of solvent together with an emulsifier. Examples of the emulsifier include sodium alkylbenzene sulfonic acid, sodium dioctyl sulfosuccinate salt, and nonylphenol ethylene oxide adduct.

[Blocked polyisocyanate compound in the first treatment agent]
The blocked polyisocyanate compound is an adduct of the polyisocyanate compound and a blocking agent. This causes the blocking component to be liberated 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, and triphenylmethane triisocyanate, or two or more of these polyisocyanates and active hydrogen atoms. A large amount of terminal isocyanate group obtained by reacting a compound having, for example, trimethylolpropane, pentaerythritol, polyalkylene glycol, etc. with a molar ratio of isocyanate group (-NCO) to hydroxyl group (-OH) exceeding 1. Valuable alcohol adduct polyisocyanate can be mentioned. In particular, aromatic polyisocyanates such as triresin isocyanate, diphenylmethane diisocyanate, and polymethylene polyphenyl isocyanate are preferable because they exhibit excellent performance.

Examples of the blocking agent include phenols such as phenol, thiophenol, cresol and resorcinol, aromatic secondary amines such as diphenylamine and xylidine, lactam such as phthalate imide, caprolactam and valerolactam, acetoxime, methylethylketone oxime and cyclohexaneoxime. Oxim and acid sodium bisulfite can be mentioned.

[Resorcin, formalin, rubber latex in the second treatment agent]
Resorcin-formalin-rubber latex is generally called RFL, and is obtained by mixing and aging an initial condensate of resorcin and formaldehyde and rubber latex. The molar ratio of resorcin to formaldehyde in this resorcin / formalin / rubber latex is, for example, 1: 0.1 to 1: 8, preferably 1: 0.5 to 1: 5. As the rubber lattice, a blend of styrene butadiene vinyl pyridine latex (VP latex) and chloroprene latex is preferably used.

[Blocked polyisocyanate compound in the second treatment agent]
As the blocked polyisocyanate compound, those described as the first treatment agent can be used. The same one used as the first treatment agent may be used, or a different one may be used.

[Chlorophenol compound in the second treatment agent]
The chlorophenol compound is preferably a compound obtained by copolymerizing parachlorophenol, resorcin and formaldehyde. Specifically, as the chlorophenol compound, a trinuclear body (compound of (I)), a pentanuclear body (compound of (II)) or a nucleolus (compound of (III)) represented by the following structural formula is used. It is preferable to use it. The chlorophenol compound may be a mixture thereof.

In these chlorophenol compounds, the ratio of parachlorophenol to resorcin / formalin is preferably 20/80 to 80/20 (weight ratio) for parachlorophenol / resorcin / formalin from the viewpoint of rubber adhesion.

[Amount of adhesion to fiber cord]
Solids (polyepoxide compound, broken polyisocyanate compound, resorcin formarin rubber latex, blocked polyisocyanate compound and chlorophenol) derived from the first treatment agent and the second treatment agent that finally adhere to the aramid fiber cord. The total amount of the compound) is preferably 1 to 6% by weight, more preferably 2 to 5% by weight, based on 100% by weight of the fiber cord before attachment. If it is less than 1% by weight, the adhesive strength is likely to be insufficient, which is not preferable, and if it exceeds 6% by weight, scum is likely to occur, which is not preferable.

〔Production method〕
In the rubber hose reinforcing aramid fiber cord of the present invention, the twisted aramid fiber cord is first treated with a first treatment agent containing a polyepoxide compound and a blocked polyisocyanate compound, and then resorcin, formarin, rubber latex, and a block. It can be produced by treatment with a second treatment agent containing a dopolyisocyanate compound and a chlorophenol compound.

Specifically, the twisted aramid fiber cord is dipped in the first treatment agent and then dried at a temperature of 130 to 180 ° C. for 2 to 5 minutes, preferably 1 to 3 minutes, and then dried at 180 to 260 ° C., preferably 220 to. Heat treatment is performed at a temperature of 250 ° C. for 0.5 to 5.0 minutes, preferably 1 to 3 minutes. The aramid fiber cord after the heat treatment is treated with the second treatment agent by contacting it with a roller or applying it by spraying from a nozzle, and then treating with the second treatment agent at 130 to 250 ° C. Dry for 0.5-5 minutes, preferably 1-3 minutes, then heat-treated at a temperature of 150-260 ° C, preferably 220-250 ° C for 0.5-5.0 minutes, preferably 1-3 minutes. To do. If the drying and heat treatment temperatures are lower than these, the adhesion to the rubber tends to be insufficient, while if the drying and heat treatment temperatures are higher than these, the adhesive itself will harden, causing the fibers to harden and undergo strong deterioration. It becomes difficult to put it to practical use.

In order to control the amount of solid content of the treatment agent attached to the aramid fiber cord, means such as squeezing with a pressure welding roller, scraping with a scrubber or the like, blowing off with air blowing, suction, and beating with a beater can be used. On the other hand, in order to increase the amount of adhesion, it may be adhered a plurality of times.

[Fiber reinforced rubber hose]
The aramid fiber cord for reinforcing a rubber hose of the present invention can be made into a fiber reinforced rubber hose having a fiber reinforcing layer by braiding it into a tubular shape by a known method and providing rubber layers in its inner layer and outer layer. In this case, it is preferable that both the inner layer and the outer rubber layer are made of ethylene propylene.

Hereinafter, the present invention will be specifically described with reference to Examples. The evaluation of the characteristics in the examples was carried out according to the following method.

(1) Cord pull-out adhesive force The cord pull-out adhesive force indicates the pull-out adhesive force between the aramid fiber cord and the rubber. A test piece was prepared by embedding the bonded fiber cord in EPDM-based unvulcanized rubber having a width of 1 cm and steam vulcanizing at a temperature of 150 ° C. for 30 minutes. The force (N) required to pull out the fiber cord from the rubber in this test piece was defined as the cord pull-out adhesive force. The compounding ratio of the rubber used for the evaluation of the cord pull-out adhesive strength is as follows. EPDM means ethylene propylene diene rubber, and EP manufactured by JSR Corporation was used. Asahi Carbon Co., Ltd. # 70 was used as HAF-carbon black.
EPDM 100 parts by weight HAF-Carbon Black 120 parts by weight Process oil (paraffin-based) 90 parts by weight Zinc oxide 5 parts by weight Stericic acid 3 parts by weight Vulcanizer 3.5 parts by weight Vulcanization accelerator 2.5 parts by weight (2) Scum dropout during braiding The adhesively treated fiber cord was braided using a braider. The state of the dip residue generated near the guide at this time was visually confirmed. When good process passability was shown with almost no scum, it was evaluated as ◯, and when scum was generated and adhered to the braider device, it was evaluated as x.
(3) Hose expansion amount A fiber reinforced rubber hose having a fiber reinforced layer between the inner layer rubber layer and the outer layer rubber layer was prepared by using it as a braided fiber cord fiber reinforced layer. The hose expansion amount of this fiber reinforced rubber hose was measured according to JIS D2601 “Automotive parts-non-mineral oil hydraulic brake hose assembly”.

[Example 1]
As the first treatment agent, a polyepoxide compound (trade name: Denacol EX611; manufactured by Nagase Kasei Co., Ltd., sorbitol glycidyl ether) and a blocked polyisocyanate compound (trade name: Elastron E-37; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) ) Was mixed at a weight ratio of 20:80 of the polyepoxide compound and the blocked polyisocyanate compound to prepare an aqueous dispersion having a total concentration of these components of 5% by weight.

Then, the second treatment agent was prepared as follows. First, the initial condensate of resorcin and formalin reacted with an acidic catalyst: Sumikanol 700S (manufactured by Sumitomo Chemical Co., Ltd., 65% by weight aqueous solution) was added to water to which an aqueous solution of caustic soda and an aqueous solution of ammonia were added, and the mixture was sufficiently stirred and dispersed. I let you. Formalin was added thereto so that the R / F (resorcin / formalin) ratio was 1: 2 (molar ratio), mixed uniformly, and aged at a temperature of 20 ° C. for 2 hours.

Next, Nippon Zeon 2518FS (manufactured by Nippon Zeon Corporation, vinylpyridine, styrene, butadiene terpolymer emulsion) and LT-50 (manufactured by Denki Kagaku Kogyo Co., Ltd., chloroprene rubber latex: 50% by weight emulsion) are mixed. (L) was mixed with the resorcin-formalin initial condensate (RF) dispersion so that the solid content ratio (RF / L ratio) was 1: 9 (weight ratio), and elastron BN-69 ( Diphenylmethane diisocyanate methylethyl ketone oxime block compound (33 wt% aqueous dispersion) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was added so as to have a solid content ratio of 6: 1 (weight ratio) with RFL, and further aged at a temperature of 20 ° C. for 24 hours. I let you.

Immediately before use, add Denabond (a 20% by weight solution of a special chlorophenol compound manufactured by Nagase Kasei Kogyo Co., Ltd.) to RFL in a solid content ratio (Denabond / RFL ratio) of 2: 1 (weight ratio) and stir well. Then, the treatment agent was adjusted. The viscosity and the amount of adhesion of the treatment agent were controlled by adding and diluting water to the treatment agent.

On the other hand, as the aramid fiber cord, a multifilament of 1000 denier technora fiber manufactured by Teijin Limited was twisted by two twisted yarns at 10 T / 10 cm to prepare an aramid fiber cord.

This aramid fiber cord is immersed in the first treatment agent using a compute treatment machine (manufactured by CA Ritzer Co., Ltd.), dried at a temperature of 150 ° C. for 2 minutes, and then dried at a temperature of 235 ° C. for 1 minute. It was heat-treated, then immersed in a second treatment agent, and then heat-treated at a temperature of 210 ° C. for 1 minute. 5% by weight of the solid content of the treatment agent was attached to the aramid fiber cord after the heat treatment. The solid content of the treatment agent is derived from the first treatment agent and the second treatment agent. Table 1 shows the evaluation results of the obtained aramid fiber cord.

[Comparative Example 1]
It was carried out in the same manner as in Example 1 except that the treatment with the first treatment agent was not carried out. 5% by weight of the solid content of the treatment agent was attached to the aramid fiber cord after the heat treatment. The evaluation results are shown in Table 1.

[Comparative Example 2]
The procedure was carried out in the same manner as in Example 1 except that the first treatment agent did not contain the polyblocked isocyanate compound. 5% by weight of the solid content of the treatment agent was attached to the aramid fiber cord after the heat treatment. The evaluation results are shown in Table 1.

The aramid fiber cord of the present invention can be suitably used as a constituent member of the fiber reinforced layer of a fiber reinforced rubber hose having a fiber reinforced layer between the inner layer rubber layer and the outer layer rubber layer. The fiber-reinforced rubber hose using the aramid fiber cord for reinforcing the rubber hose of the present invention can be suitably used as a brake hose for an automobile skid prevention device.

Claims (4)

Aramid fiber cord for reinforcing a rubber hose used as a fiber reinforcing layer of a fiber reinforced rubber hose having a fiber reinforcing layer between the inner layer rubber layer and the outer layer rubber layer, and twisted aramid fibers are first subjected to a polyepoxide compound and blocked. It is characterized by being produced by treating with a first treatment agent containing a polyisocyanate compound, and then with a second treatment agent containing resorcin, formalin, rubber latex, blocked polyisocyanate compound and chlorophenol compound. Aramid fiber cord for reinforcing rubber hoses. A reinforcing layer containing the rubber hose reinforcing aramid fiber cord according to claim 1, a first rubber layer provided on one surface thereof, and a second rubber layer provided on the other surface of the fiber cord reinforcing layer. A fiber-reinforced rubber hose in which the first rubber layer and the second rubber layer are made of ethylene propylene rubber. The fiber-reinforced rubber hose according to claim 2, which is used as a brake hose for an automobile. A method for manufacturing a aramid fiber cord for reinforcing a rubber hose, which is used as a fiber reinforced layer of a fiber reinforced rubber hose having a fiber reinforcing layer between an inner layer rubber layer and an outer layer rubber layer. It is characterized in that it is treated with a first treatment agent containing a compound and a blocked polyisocyanate compound, and then with a second treatment agent containing a resorcin / formarin rubber latex, a blocked polyisocyanate compound and a chlorophenol compound. A method of manufacturing aramid fiber cords for reinforcing rubber hoses.