JPS60181369A - Production of carbon fiber code for reinforcing rubber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a carbon fiber cord for reinforcing rubber, which has good adhesion to rubber and excellent fatigue resistance in rubber.

Carbon fiber, which has excellent properties such as high modulus of elasticity, strength, dimensional stability, heat resistance, and chemical resistance, has been used as a rubber reinforcing material for a long time. Disclosed in books, etc. In addition, Japanese Patent Publication No. 55-55998 discloses a two-stage treatment method using an epoxy compound and a resorcinol/formaldehyde condensate/comb latex mixture (hereinafter referred to as RFL) to impart adhesion to rubber to carbon fibers. and even after the gluing process.

Japanese Patent Publication No. 53-30757 and Japanese Patent Publication No. 57-464 disclose a method of obtaining a rubber reinforcing cord by applying a specific twist to minimize strength loss due to twisting and improving fatigue life.
It is disclosed in Publication No. 27.

However, although the adhesive treatment method disclosed in Japanese Patent Publication No. 5B-33998 was sufficiently effective in providing adhesiveness to the carbon fiber t-coat, the conditions (epoxy Compounds in general, specifically water-insoluble epoxy compounds (with an RFL deposition amount of 5 to 50%, particularly 10 to 20%), have a sufficient effect on the fatigue resistance of carbon fibers in rubber. Strength: I couldn't do it. Also, the above-mentioned Special Publications No. 55-30757 and No. 57-464
Although the method disclosed in Publication No. 27 also shows an improvement in fatigue life.

Its fatigue resistance was still not sufficient for practical use.

Therefore, the present inventors not only have excellent adhesive properties.

As a result of studies aimed at obtaining a carbon fiber cord for rubber reinforcement that also has excellent fatigue resistance, it was found that a relatively large amount of a mixture of an epoxy compound and rubber latex was attached to a bundle of carbon fiber yarns, and then RFI and treatment were performed. It has thus been discovered that a rubber-reinforcing carbon fiber cord with dramatically improved fatigue resistance while maintaining good adhesion to rubber can be obtained, and the present invention has been achieved.

That is, in the present invention, an epoxy compound (E
) and rubber latex CL) at solid content weight ratio II)
/CL) = 1/9 to 9/1 blend (
To provide a method for producing a carbon fiber cord for rubber reinforcement, characterized in that 10 to 80% by weight of FiL (hereinafter referred to as FiL) is applied and then heat treated, and then 0.5 to 10% by weight of RFL is applied and then heat treated. It is.

The carbon fiber yarn bundle to be subjected to the treatment method of the present invention may be carbonized or graphitized, and has a single yarn fineness of about 0.4.
It is preferable that the yarn bundle has a denier of ~2.0 denier and a total denier of about 5,000 or less, and is particularly sized with a surfactant liquid containing an epoxy compound. Further, the yarn bundle may be heated as necessary, and heating is preferably carried out in the RPL processing factory process and/or in the subsequent process.The twisting in the carbon fiber cord as a final product is , Number of twists (twists/10m) x
It is desirable that the twist coefficient represented by the formula ``Shiraso'' is 900 or less, and preferably 600 or less.

As the epoxy compound (Fi') used in the present invention, any compound may be used as long as it has at least one epoxy group in one molecule.2For example, the reaction between polyhydric alcohol or polyhydric phenol and epichlorohydrin. Examples include those obtained by treating the product with an alkali. In this case, as a polyhydric alcohol. For example, glycerin, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, hexatorio-AI, polyacrylic alcohol, polyvinyl alcohol, inositol, trimethylolpropane, 1.4-dimethylolbenzene, sorbitan, etc. are used; As the phenol, resorcinol, hydroquinone, bisphenol A1 phloroglycitol, catechol, etc. are used. This epoxy compound is used as an aqueous solution by dissolving or emulsifying it in water or as a solution using an organic solvent.

On the other hand, examples of the rubber latex (L) used in the present invention include natural rubber and synthetic rubber latex, and examples of the synthetic rubber latex include styrene phtadiene copolymer, polybutadiene, vinylpyridine styrene butadiene copolymer, and acrylonitrile butadiene copolymer. Examples include aqueous dispersions of one or more of these polymers, polychloroprene, and the like.

The mixing ratio of the mixture (EL) of epoxy compound [E] and rubber latex CI, ) is (K)/in terms of solid content weight ratio.
(L') = 1/9 to 9/1, preferably (It)
/(L) = 5/7 to 7/3. [E]/
If (L) is less than 1/9, excellent adhesion with rubber cannot be obtained, and if (E) / (L) exceeds 9/1, the cord after heat treatment will become hard and have poor fatigue resistance. Therefore, it is undesirable.

The mixture of epoxy compound and rubber latex (PCL) needs to be added in an amount of 10 to 80% by weight, preferably 10 to 60% by weight* ("L) If the amount of adhesion is less than 10% by weight Fatigue resistance decreases, and if it exceeds 80% by weight, tackiness increases and process failure occurs, which is undesirable.The amount (applied amount) herein is defined in the written description.

The heat treatment after the (EL) impregnation is aimed at drying and condensation of (EI,), and is carried out at a temperature of 100 to 260°C. More preferably, the first stage of drying is first carried out at a temperature of 100 to 160°C, and then the temperature is 180 to 20°C.
It is preferable to perform the second stage heat treatment at a temperature of 60°C.

R and PL used in the present invention are mixed adhesives of resorcinol/formaldehyde condensate and rubber latex, and those in which the rubber component accounts for the majority of the active ingredients are preferably used.

In RFL, if the rubber latex component is large, the processed fiber becomes flexible, which is preferable in terms of post-processability, but on the other hand,
If the amount of the resorcinol-formaldehyde condensate is too small, the adhesion between the fiber and the rubber will deteriorate, which is not preferable. Therefore, R.F.
In L, the compositional weight ratio of the resorcinol-formaldehyde condensate to the rubber is preferably from 1:1 to 1:10, particularly preferably from 1:2 to 1:10.

The resorcinol-formaldehyde condensate used for RFL is composed of resorcinol (R) and formaldehyde (,F) in a molar ratio [R]/[F] of [R]/(F)=1/[13~1
It is desirable to have a wasteful value of 73.0.

Examples of rubber latex liquids used in RFL include aqueous dispersions of natural rubber, styrene-butadiene copolymer, polybutadiene, vinylpyridine-styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polychlorogrene, etc. It leaks.

For RFL, block isocyanates, ethylene urea, polyhydric phenol polysulfides (Japanese Patent Publication No. 1987-8733) or 2.6-bis(2
/ , 4/-dihydroxy-phenylmethane) -4
-'Chlorophenol/I/ (Japanese Patent Publication No. 46-11251) can be partially included, and a silicone oil emulsion or a surfactant containing a smooth array can be added to reduce process problems. That's not possible.

The amount of RFL applied to the carbon fiber yarn bundle is:

0.5 to 10% by weight, especially 2 to 6% by weight in terms of adhesion amount
If it is less than 0.5% by weight, the adhesion to the rubber will be insufficient, and if it exceeds 10% by weight, the post-processability and the adhesion to the rubber will deteriorate, which is not preferable.

The carbon fiber yarn bundle after RFL and impregnation needs to be heat treated for drying, and this heat treatment is carried out at 100 to 260°C.

Thus, the carbon fiber cord for rubber reinforcement obtained by method 1 of the present invention has excellent adhesion to rubber and fatigue resistance in balance, and is a rubber composite that takes advantage of the characteristics of carbon fiber such as high strength and high modulus. It is extremely useful in material applications such as tires, conveyor belts, rubber hoses, rubberized fabrics, etc.

Next, the present invention will be explained with specific examples.

In Example t, the amount of KL and RFL deposited, the adhesive strength, and the GY fatigue life were measured according to the following methods.

(1) Adhesion amount (RPU): Determined from the following formula.

w2 -w.

RP'U (%) = j
g) W2 = weight of carbon fiber after treatment with length 100α (g) (2) The treatment system that has obtained adhesive strength is combined with a rubber compound of the primary composition to obtain 1
Pressure vulcanization was performed at 40°C for 40 minutes.

Composition of rubber compound Parts by weight Natural rubber 70 Styrene-butadiene rubber 30 Carbon black (5RF) 40 Stearic acid 2 Zinc Flower 5 Naphthenic process oil 3 Vulcanization accelerator 2.5 (Dibenzothiazyl disulfide) Sulfur 2 Adhesion The force measurement method is JIS L1017-1983 A.
The test was conducted under the following conditions according to the method (T test).

Embedded length of cord in rubber: 1αOx Width of embedded sample rubber piece: Io, 0+11〃 Length: 3o, otm Slit width of pull-out clamp: 1.0111 (3)
GY fatigue life JIS L+Qj7-1983? -L-7' Fatigue strength The bending angle was 90'' according to method A (Gutsdoyer method), and the time (minutes) until the tube broke due to fatigue was measured.The composition of the rubber compound was Adhesive Force Measurement The same compound as the rubber used was used, and the number of sample cords of 1800 denier was set at 26 cords/inch.

Examples-1 to 14, Comparative Examples-1 to 4 11 Trading card T-S OO” (Tokyo) (manufactured by Shikushi Co., Ltd.) was used.

The carbon fiber yarn bundle was impregnated (
After drying at 120'C% for 5 minutes, heat-treating at 210°C for 2 minutes, impregnating it with RFL having the following composition, squeezing it at 120'C%. ℃ for 2 minutes, then 210℃,
Heat treatment was performed for 1 minute.

(Composition of RFL) Water 4 0 5.6 g Resorcinol 1a9 Formalin (67%) 2 Z 910%
NaO[('5.2) was mixed and aged at 20°C for 2 hours to obtain liquid A.

Next, 414.6 g of rubber latex (4 (L5 weight: 96)), 10a4 of water, and 45z6 of liquid A were mixed and prepared, and the mixture was aged at 20°C for 12 hours to obtain RFL.

The properties of the resulting cord, which was obtained by arranging two bundles of treated fibers and twisting them in the Z direction at 3 times/10α, are shown in the table.

As is clear from the table, the treated cords obtained by the method of the present invention have dramatically improved GY fatigue life and have balanced and excellent adhesion to rubber.

Patent applicant Higashi Shikikai Co., Ltd.

Claims (1)

[Claims] Epoxy compound (Fi) and rubber latex (L) are added to the carbon fiber yarn bundle at a solid content weight ratio [E]/(L)-=1/
It is characterized by applying 10 to 80% by weight of a mixture of 9 to 9/1, followed by heat treatment, and then applying 0.5 to 10% by weight of a resorcinol/formaldehyde condensate/rubber latex mixture, followed by heat treatment. Method for manufacturing carbon fiber cord for rubber reinforcement.