JPH04103634A - Reinforcing fiber for rubber - Google Patents

Abstract

PURPOSE:To obtain the subject fiber capable of providing belts having a high dedendum strength even when used at a high temperature and speed for a long period without causing peeling or cracking by forming a layer containing a water-soluble condensate of resorcin formaldehyde and specific two kinds of copolymer latexes on a glass fiber core wire. CONSTITUTION:The objective fiber is obtained by forming the first layer containing a water-soluble condensate of resorcin formaldehyde, a vinyl pyridine- styrene-butadiene copolymer latex and an acrylonitrile-butadiene copolymer latex on a core wire composed of glass fiber, and further the second layer containing a hydrogenated nitrile rubber having 30-50wt.% acrylonitrile group content and 2-40 iodine value and a crosslinking agent on the first layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to rubber reinforcing fibers, particularly rubber reinforcing fibers suitable for reinforcing toothed belts using hydrogenated nitrile rubber as a matrix rubber.

[Prior Art] In order to increase the strength of rubber products such as rubber belts and tires, reinforcing fibers such as glass fiber m-yarn are widely used.

Rubber products such as rubber belts are subject to repeated bending stress, resulting in bending fatigue, resulting in a decrease in performance, and peeling between the reinforcing material and the rubber matrix.

In order to prevent such peeling or performance deterioration and obtain a sufficient reinforcing effect, it is necessary to increase the compatibility and adhesive strength between the reinforcing fibers and the rubber. be done.

Various compositions of processing agents have been proposed.

For example, a processing agent using a combination of a vinyl-gin-styrene-butadiene terpolymer latex and a water-soluble condensate of resorcinol and formaldehyde.

Alternatively, various processing agents such as those containing rubber latex have been proposed (see JP-A-55-114551).
.

Further, a first liquid (RFL liquid) containing a water-soluble condensate of resorcin formaldehyde and rubber latex is applied to the rubber reinforcing m fibers to form a first layer containing the resorcin formaldehyde condensate and rubber on the fiber, It is also known that the layer is then treated with an overcoat solution containing rubber latex and isocyanate to form a second layer containing isocyanate and rubber (see JP-A-49-14546).

Furthermore, it has also been proposed to use H-NBR latex as the rubber latex to be contained in RFL (see Japanese Patent Laid-Open No. 63-270877).

[Problems to be Solved by the Invention] Conventional treatment liquids for rubber reinforcing fibers and conventional methods for treating rubber reinforcing fibers have the following problems.

(1) Sufficient adhesive strength cannot be obtained.

(2) It is difficult to obtain rubber products with sufficient bending strength.

(3) Adhesiveness decreases when used at high temperatures. That is, heat resistance is insufficient.

Recently, with the rise in temperature near automobile engines, heat-resistant rubbers such as chlorosulfonated polyethylene and hydrogenated nitrile rubber (H-NBR) have come to be used as rubber for timing belts. However, since such heat-resistant rubber, especially H-NBR, has adhesive properties and is smaller than ordinary rubber, the above-mentioned drawbacks tend to be greater than ordinary rubber, making it difficult for timing belts to withstand long-distance running. cannot be obtained.

It is said that the above-mentioned problems can be overcome to some extent by treating the rubber reinforcing fibers with an RFL solution and then with an overcoat solution containing rubber latex and isocyanate. There are problems.

(1) Adhesive strength decreases over time.

(2) In order to obtain a sufficient effect, it is necessary to use a large amount of isocyanate, and increasing the amount of incyanate deteriorates the stability of the solution, making it necessary to prepare a small amount of overcoat solution each time it is used. be.

(3) RFL layer (first layer) and overcoat liquid layer (second layer)
The interfacial adhesion between the first and second layers is poor, and peeling easily occurs between the first and second layers.

Although the method of using an RFL liquid containing H-NBR latex is particularly effective when the matrix rubber is H-NBR, this method also has the following drawbacks.

That is, it is necessary to use an aqueous emulsion as the rubber latex to be contained in the RFL liquid. H-N
Although it is technically possible to produce an aqueous emulsion containing BR, the manufacturing process is complicated and the cost increases significantly.

Furthermore, as the performance of automobile engines increases, tooth base strength of the toothed belt is high enough to prevent peeling or cracking at the tooth base even when used for long periods of time at high speeds and high temperatures. This may have been due to the development of belts, but there was no known product that satisfied these demands.

The present invention solves the problems of the prior art described above, and even when used under high temperature conditions such as being subjected to repeated bending stress,
To obtain rubber reinforcing fibers that do not reduce adhesive strength over time, have high heat resistance, and have low manufacturing costs, and are suitable for reinforcing H-NBR, especially toothed belts with high tooth root strength. The purpose of this invention is to provide fibers suitable for reinforcing rubber.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a water-soluble condensate of resorcin formaldehyde, a vinyl pyridine-styrene-butadiene copolymer latex, and acrylonitrile are coated on a core wire made of glass fiber. - a first layer comprising a butadiene copolymer latex, preferably a first layer comprising a butadiene copolymer latex;
For reinforcing rubber, a second layer containing a hydrogenated nitrile rubber having an acrylonitrile group content of 30 to 50 wt% and an iodine value of 2 to 40, and a crosslinking agent and preferably a reinforcing agent such as silica or carbon black is formed on the layer. Using fiber,
Preferably, the second layer further contains an unsaturated carboxylic acid metal salt, in which case an organic peroxide is used as the crosslinking agent.

Next, the present invention will be explained in more detail.

First, the liquid (first liquid) to be applied onto the core wire in order to form the first layer will be explained.

A water-soluble condensate of resorcin formaldehyde (hereinafter simply referred to as a condensate) is a mixture of resorcin and formaldehyde rich in oxymethyl groups obtained by reacting resorcin formaldehyde in the presence of an alkaline catalyst such as a water-obscuring alkali, ammonia, or an amine. Water-soluble initial addition condensates (resols) can be suitably used. In particular, the molar ratio of resorcinol and formaldehyde is 1:0.3 to 2.
It is preferable to react at a ratio of 5:5 to 5:5.

As the vinylpyridine-styrene-butadiene terpolymer latex (abbreviated as terpolymer latex), one in which the weight ratio of vinylpyridine, styrene, and butadiene is 10 to 20:10 to 20:60 to 80 is particularly suitable. (Product name, manufactured by Sumitomo Naugatuck Co., Ltd.), 0650 (Product name, manufactured by Japan Synthetic Rubber Co., Ltd.), N
1pol 2518FS (trade name, manufactured by Nippon Zeon Co., Ltd.) etc. can be suitably used.

Further, as the acrylonitrile-butadiene copolymer latex, for example, N1pol 1562 or 1572
(trade name, manufactured by Nippon Zeon Co., Ltd.) can be suitably used.

Note that the first liquid contains chlorosulfonated polyethylene (C3
M) More favorable results can be obtained with scales by adding latex.

The chlorine content of the chlorosufflefluoronated polyethylene latex is preferably 20 to 40 wt%, preferably 25 to 35%.
wt%2 S content in sulfon group is 0.5 to 2.0w
t% preferably 1.1~! , 4 wt % or whatever is appropriate, and raw rubber with a Mooney viscosity of 30 to 95 can be suitably used.

Further, a part of the C5M latex (50 wt% or less, preferably 25 wt% or less) can be subjected to M test using chlorobrene (CR) or hydrogenated nitrile rubber (H-NBR) latex.

In addition, H-NBR having an iodine value and an acrylonitrile content of 2 to 40.30 to 50 wt%, preferably 3 to 30.35 to 45 wt%, respectively, can be suitably used, and can be prepared by a known method. It is possible to manufacture latex.

The condensate and the latex described above are mixed to form a first liquid.

The weight content of each component of the first liquid is whether it is a condensate as a solid content,
0.5 to 10 wt%, preferably 1 to 5 wL%, terpolymer latex 5 to 25 wt%, preferably 10 to
20 wt%, acrylonitrile butadiene latex, 5 to 25 wt%, preferably 10 to 20 wt%.

In addition, 1 chlorosulfonated polyethylene latex
Even better results can be obtained by adding up to 10 wt%, preferably 2 to 7 wt%.

The concentration of the first liquid may be appropriately determined to be 20 to 40 wt%, preferably 25 to 35 wt% in terms of the total amount of all components or solid content.

Additionally, an anti-aging agent such as a mineral oil emulsion or wax may be added to the first liquid.

The solid content of the anti-aging agent is O, 1 to 2 wt%, preferably 0.3 to lvt%.

Next, the liquid (second liquid, overcoat liquid) with which the second layer is to be formed will be explained.

The overcoat liquid is a so-called rubber paste made of an adhesive composition prepared by kneading hydrogenated nitrile rubber and a crosslinking agent in advance, or dissolved in an appropriate solvent in an uncrosslinked state.

The hydrogenated nitrile rubber has an iodine value of 2 to 40, preferably 3 to 30, and an acrylonitrile group content of 30 to 50 wt.
%, preferably 35 to 45 t%.

As a crosslinking agent, sulfur, tetramethylthiuram disulfide, 4 parts by weight per 100 parts by weight of hydrogenated nitrile rubber
．． 0 of sulfur-containing crosslinking agents such as 4'-cythiobisdimorpholine
．． 5 to 10 parts by weight or dicumyl peroxide, l,
using 1 to 10 parts by weight of an organic peroxide such as 3-bis=(t-butylperoxy-isopropyl)benzene, 2°5-dimethyl, 2,5-cy(t-butylperoxy)hexane, or 1 to 40 parts by weight of unsaturated carboxylic acid metal salt,
Particularly favorable results can be obtained by desirably using 5 to 20 parts by weight. The unsaturated carboxylic acid metal salt is preferably a di(meth)acrylic acid metal salt, and zinc dimethacrylate, aluminum dimethacrylate, etc. are preferably used.

Further, a reinforcing agent can be added to the adhesive composition for the purpose of increasing its strength.

The reinforcing agent may be any commonly used reinforcing agent such as silica, carbon black, etc., and is not particularly limited. By using silica, even better adhesive strength can be achieved.

Furthermore, the adhesive composition may contain a filler, a softener, an anti-aging agent, a vulcanization accelerator, etc. as necessary.

The overcoat liquid contains 100 parts by weight of the adhesive composition,
Usually, it is obtained by dissolving it in 600 to 800 parts by weight of a solvent, but the amount of solvent is not particularly limited, and the viscosity of the rubber glue is determined optimally from the viewpoint of coating workability, amount of adhesion to reinforcing fibers, etc. be selected accordingly. Further, the solvent is not particularly limited, such as methyl ethyl ketone, toluene, xylene, etc., but methyl ethyl ketone is preferably used.

As the core wire used in the present invention, it is practical to use glass mti.6For example, a bundle of glass mti, which is made by applying a sizing agent to E-glass fibers with a thickness of 9μ and concatenating about 200 fibers, is preferably used. can.

In addition, the tensile strength of glass fiber is 300Kg/m.
The performance of rubber products reinforced with glass fibers can be improved by using high-strength glass fibers of m 2 or more, especially glass fibers having the following composition.

Sing 55-65 wt% Al2Off 20-26 wt% Ca00-10 wt% Mg07-12 wt% B20.0-1 wt% R200-0.5 wt% Furthermore, the diameter of the glass fiber is 8 or less, preferably 7.
The performance can be improved by setting the following in 5.

The diameter of the glass fiber is 3iL or more, preferably 5u.
It is appropriate to make the diameter less than L. If the diameter is made too small, the manufacturing cost will increase.

Three such reinforcing fiber bundles are arranged, and 12 to 25 wt %, preferably 16 to 22 wt % of the first liquid is applied thereto according to a conventional method.

After applying the first liquid, preferably after sufficiently drying, an overcoat liquid is applied according to a conventional method. Drying of the first liquid is 200
It is desirable to carry out the process at ~350°C.

The amount of overcoat liquid applied is 0.5 to 0.5 to the amount of reinforcing fiber.
A suitable amount is 5 wt%, preferably 2 to 4 wt%. Preferably at 120-200℃ after applying the second liquid
Dry in .

In addition, the reinforcing fiber coated with the above-mentioned first liquid has a thickness of 2°54 cm.
(1 inch) of S or Z twist (pre-twist) of about 0.5 to 4.0 per inch is further aligned about 2 to 13 pieces to create a twist of about 0°5 to 3.0 per 2.54 cm. It is preferable to give the yarn a twist in the opposite direction to the first twist (first twist) and then apply an overcoat liquid to the yarn.

There is no particular limitation on the type of rubber to be reinforced with the rubber reinforcing fibers of the present invention, but Hypalon, nitrile rubber, hydrogenated nitrile rubber, etc. can be exemplified. Rubber products such as timing belts can be obtained.

[Operation] A first layer containing a water-soluble condensate of resorcin formaldehyde, a vinyl pyridine-styrene-butadiene copolymer latex, and an acrylonitrile-butadiene co-aggregate latex is placed on the core wire made of co-glass fiber. By using rubber reinforcing fibers formed with a second layer containing a hydrogenated nitrile rubber with an acrylonitrile group content of 30 to 50 wt% and an iodine value of 2 to 40 and a crosslinking agent, rubber (matriclas rubber) and reinforcing fibers can be used. Adhesive strength with
Even when used under conditions of high temperature and repeated stress, it prevents deterioration over time.
Increases the interfacial adhesion between the RFL layer and the overcoat layer to prevent peeling and increase dentinal strength.

[Example] Vinylpyridine-styrene-butadiene terpolymer latex containing vinylpyridine, styrene, and butadiene in a ratio of 15:15 to 0 (2518FS, trade name, manufactured by Nippon Zeon Co., Ltd., terpolymer content 40 .5w
An aqueous solution containing 23 wt % of an addition condensate (resol) of resorcin and formaldehyde, which was reacted in the presence of an alkaline catalyst at a molar ratio of resorcin and formaldehyde of 1:0.7. 12 parts by weight of nitrile-butadiene copolymer latex (N1p
ol 1562 trade name, manufactured by Nippon Zeon Co., Ltd., 36 parts by weight of nitrile-butadiene copolymer content 41 wL%),
CSM latex (450, product name, manufactured by Sumitomo Seika Co., Ltd., C
A mineral oil emulsion (mineral oil content 55 wt%) was further added as an anti-aging agent to a mixture of 5.5 parts by weight (SM content 40 yt%).
%) and 1.5 parts of ammonia water (concentration 18 wt%) were added to obtain a first solution.

The overcoat liquid is hydrogenated nitrile rubber (ZP20
00. 100 parts by weight of zinc oxide (Zinc White No. 1, manufactured by Sakai Chemical Co., Ltd.), 100 parts by weight (trade name, manufactured by Nippon Zeon Co., Ltd.), 10 parts by weight of zinc oxide (R-20S, manufactured by Asada Chemical Co., Ltd.), 15
Parts by weight, 30 parts by weight of silica (Curve Nox #67, trade name, manufactured by Shionogi & Co., Ltd.), dicumyl peroxide (
100 parts by weight of an adhesive composition consisting of 5 parts by weight of Percmill D (trade name, manufactured by NOF Corporation) was mixed with 75 parts by weight of methyl ethyl ketone.
It was dissolved and adjusted to 0 parts by weight.

The first liquid was applied to three glass fiber bundles made by converging 200 pieces of glass SL/1 in accordance with a conventional method (
After drying at 250°C for 1 minute (solid content: 17 wt%), this glass fiber bundle was given 4.0 Z twists (pre-twist) per 2.54 cm, and the fiber bundles with this pre-twisting were then twisted with 11 pieces of wood. The overcoat liquid was applied to the pieces that were pulled together and subjected to 2.1 S twists (ply twists) per 2.54 cm.
A test piece was created using it as a reinforcing fiber.

Type of rubber: 100 parts by weight of hydrogenated nitrile rubber: 30 parts by weight of carbon braque, 10 parts by weight of zinc white, 2 parts by weight of anti-aging agent, 6 parts by weight of crosslinking agent, 15 parts by weight of co-crosslinking agent, 5 parts by weight of plasticizer. A combination of parts.

2. Formation of Test Pieces: Four timing belts were prepared according to a conventional method using rubber having the composition shown below.

(a) Using this timing belt, a multi-bending running test machine (6,000 rpm) in an atmosphere of 100°C
A bending durability test was conducted on the belt using the following method, and the low strength f was measured.

(b) A durability test on the tooth base of the belt was conducted using the testing machine described in f.

The above test results (average values) are shown in the attached table.

[Comparative example] In place of the first liquid in the example, the same copolymer of vinylpyridine, styrene and phthadiene Latte Nx 55 as in the example was used.
Parts by weight, 7.7 parts of polymerized resorcin formaldehyde condensate, 16 parts by weight of SBR latex (SN534, trade name, manufactured by Sumitomo Naugatac), and the same amount of the same amount of the same anti-N-L agent and aqueous ammonia as in the example were added. A first solution was prepared.

In addition, 4 wt% of the CSM formulation was added to isocyanate (MR-
200, trade name, manufactured by Nippon Polyurethane Co., Ltd.) 1.1wt
A toluene solution containing 1.5 wt % of a vulcanizing agent (Actor-DQ, trade name, manufactured by Kawaguchi Chemical Co., Ltd.) and 2.0 wt % of carbon black was prepared and used as an overcoat liquid.

The results of the same experiment as in the example using the first liquid and the overcoat liquid are shown in the attached table.

[Effects of the invention] Even when used for long periods of time at high speeds and high temperatures! A111, it is possible to obtain a belt with high southern strength without cracking.

Claims (3)

[Claims] (1) A water-soluble condensate of resorcinformaldehyde, vinylpyridine-styrene-
A rubber reinforcing fiber comprising a layer containing a butadiene copolymer latex and an acrylonitrile-butadiene copolymer latex. (2) A first layer containing a water-soluble condensate of resorcin formaldehyde, vinyl pyridine-styrene-butadiene copolymer latex, and acrylonitrile-butadiene copolymer latex on a core wire made of glass fiber,
Acrylonitrile group content 30-50wt% on the first layer
, hydrogenated nitrile rubber with an iodine value of 2 to 40, and a rubber reinforcing fiber formed with a second layer containing a crosslinking agent. (3) A first layer containing a water-soluble condensate of resorcin formaldehyde, vinyl pyridine-styrene-butadiene copolymer latex, and acrylonitrile-butadiene copolymer latex on a core wire made of glass fiber,
Acrylonitrile group content 30-50wt% on the first layer
, hydrogenated nitrile rubber with an iodine value of 2 to 40, an unsaturated carboxylic acid metal salt, and a crosslinking agent, forming a second layer for reinforcing rubber.