JPH0480138B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for producing rubber reinforcing fibers used for reinforcing rubber products such as rubber belts and tires. (Prior Art) Reinforcing fibers such as glass fiber yarn are widely used to increase the strength of rubber products such as rubber belts and tires. Rubber products such as rubber belts are subject to repeated bending stress, resulting in bending fatigue and reduced performance. Peeling occurs between the reinforcing material and the rubber matrix, or the reinforcing fibers wear out, resulting in a decrease in strength. In order to prevent such peeling and obtain sufficient reinforcing effect,
It is necessary to increase the compatibility and adhesion between the reinforcing fibers and the rubber, and for this purpose a treatment agent is applied to the surface of the reinforcing fibers. Recently, toothed belts have come to be used instead of chains to drive the camshafts of automobiles.
High-performance belts have become required as belts have a longer service life due to maintenance-free operation and higher output due to the adoption of turbo charge. Treatment agents of various compositions have been proposed in the past. There is no known treatment agent that does not cause peeling between the two and has sufficient heat resistance. For example, a processing agent using a combination of a vinylpyridine-styrene-butadiene terpolymer latex and a water-soluble condensate of resorcinol and formaldehyde;
Or NBR (acrylonitrile, butadiene rubber),
Various processing agents have been proposed, including processing agents to which rubber latexes such as SBR (styrene, butadiene rubber) and CR (chloroprene rubber) are added. (Unexamined Japanese Patent Publication 1973-
(Refer to No. 114551) By using such a treatment agent, the bonding force (adhesive force) between the reinforcing material and the rubber matrix can be sufficiently increased, but the strength may decrease when subjected to repeated bending stress. Peeling easily occurs between the reinforcing fibers and the rubber matrix, which shortens the service life, and has low heat resistance.Also, the reinforcing fibers tend to wear easily, resulting in a decrease in strength. I couldn't get the belt. (Problems to be Solved by the Invention) The present invention aims to solve the above-mentioned drawbacks of the prior art. [Structure of the Invention] (Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems, and includes treating fibers with a first liquid containing a fluororesin latex and then drying the fibers. The water content is adjusted to 2 to 20 wt% of the fluororesin, and then treated with a second liquid containing a terpolymer latex of vinyl pyridine-styrene-butadiene, rubber latex, and a water-soluble condensate of resorcinol-formaldehyde, and then dried. The present invention provides a method for manufacturing rubber reinforcing fibers. Next, the present invention will be explained in more detail. Examples of fluororesin latex include polytetrafluoroethylene latex, tetrafluoroethylene-propylene copolymer latex, polyhexafluoropropylene latex, etc.
Particularly favorable results can be obtained when polytetrafluoroethylene latex is used. The concentration of latex is 20-50wt%, preferably
A suitable concentration is 25 to 40 wt%; if this concentration is too low, sedimentation of latex particles may occur or the amount of adhesion to fibers may be insufficient. Also, if this concentration is too high, the amount of adhesion to the fibers tends to be excessive. In the present invention, the reinforcing fibers to be treated with the first liquid are not particularly limited, but it is practical to use glass fibers. For example, a bundle of three glass fibers made by adding a sizing agent to glass fibers having a thickness of 9 μm and converging approximately 200 glass fibers into three bundles can be suitably used. Although there are no limitations on the means for treating the reinforcing fibers with the first liquid, it is practical to continuously supply the reinforcing fibers and pass them through an impregnating tank filled with the first liquid. Can be impregnated uniformly. The amount of the first liquid to be added to the reinforcing fibers is 10% of the reinforcing fibers as solid content.
A suitable amount is ~25wt%, preferably 14-20wt%; if this amount is too small, the effect of the present invention will not be sufficient, and if this amount is too large, separation of the rubber matrix and reinforcing fibers will easily occur. Become. Prior to treatment with the second liquid, the reinforcing fibers treated with the first liquid are dried to form a fluororesin layer on the reinforcing fibers. At this time, the moisture content is 2 to 2 of the solid content of the fluororesin.
It is important to set the drying conditions so that the content is 20 wt%, preferably 8 to 10 wt%. After drying in this manner (hereinafter referred to as incomplete drying), when treated with the second liquid described below, the fluororesin and the components of the second liquid mix on the surface of the fluororesin layer, forming a mixed layer. Also, the portion in contact with the reinforcing fibers is composed only of fluororesin. Then, a surface layer composed only of the components of the second liquid is formed on the mixed layer. Although the drying temperature and drying time are determined in relation to each other, the preferred drying conditions are 200 to 350°C and about 1 to 10 seconds. If the drying is too complete and the water content is low, the mixed layer will not be formed sufficiently, and the surface layer formed by the fluororesin layer and the second liquid will easily peel off, reducing the life of the belt. Also, if the degree of drying is low and the moisture content is too high, the fluororesin layer will peel off and fall off due to friction with the guide used to impregnate the second liquid, making it difficult to relieve stress when subjected to repeated stress. It becomes insufficient, the lifespan decreases, and sufficient effects cannot be obtained. Next, the second liquid will be explained. The vinylpyridine-styrene-butadiene terpolymer latex (hereinafter referred to as terpolymer latex) has a weight ratio of vinylpyridine, styrene, and butadiene of 10 to 20:10 to 20:60.
~80 is particularly suitable, Pyratex (trade name,
0650 (trade name, manufactured by Nippon Synthetic Rubber Co., Ltd.), Nipol 2518FS (trade name, manufactured by Nippon Zeon Co., Ltd.), etc. can be suitably used. As the rubber latex, a latex with a relatively low degree of polymerization used as a treatment agent for rubber reinforcing fibers, particularly SBR rubber latex, is suitable.
0652 (trade name, manufactured by Japan Synthetic Rubber Co., Ltd.), J-9049 (trade name, manufactured by Sumitomo Nogatatsu Co., Ltd.), etc. can be suitably used. A water-soluble condensate of resorcin-formalin (hereinafter simply referred to as a condensate) is produced by reacting resorcin and formaldehyde in the presence of an alkaline catalyst such as an alkali hydroxide, ammonia, or an amine. Highly water-soluble initial addition condensates (resols) can be preferably used. Particularly preferred is one in which resorcinol and formaldehyde are reacted at a molar ratio of 1:0.3 to 2.5. In the present invention, in the second liquid, the ratio of latex to the total amount of terpolymer latex and latex (referred to as total latex) is 2.5 to 50 wt%,
The ratio of condensate to total latex is 2.5~25wt
It is appropriate to uniformly mix the three components according to a conventional method so that the amount is within the range of %. Note that all of the above ratios are based on solid content. If the ratio of latex to total latex is too large, the tackiness of the reinforcing fibers treated with the second liquid of the present invention becomes excessive, which tends to cause trouble in the yarn twisting process, and also tends to reduce heat resistance. If the above ratio is too small, the effect of preventing peeling when subjected to repeated stress will be insufficient, and peeling will easily occur especially when used in a high temperature and high humidity environment. If the ratio of the condensate to the total latex is too large, the reinforcing fibers treated with the treatment agent of the present invention will become hard and prone to bending fatigue. Furthermore, if this ratio is too small, the adhesive strength with the rubber matrix tends to decrease. The concentration of the above-mentioned mixture (second liquid of the present invention), that is, the terpolymer latex, latex,
The weight% of the total amount of condensate is 10-50%, preferably 20
A value of ~40% is appropriate. If the concentration is too low, adhesion to reinforcing fibers will be insufficient, and if the concentration is too high, stability will deteriorate and gelation will occur easily. The second liquid of the present invention contains the above-mentioned terpolymer latex, latex, and condensate as essential components, but if necessary, a latex stabilizer, anti-aging agent, etc. may be added. The first liquid is applied and the partially dried reinforcing fibers are treated with the second liquid. Although there are no limitations on the treatment means, it is practical to continuously supply the reinforcing fibers and pass them through an impregnating tank filled with the second liquid. The amount of the second liquid applied is 1 to 10% of the reinforcing fiber as solid content.
It is appropriate to set the amount to 10wt%, preferably 2 to 5wt%; if this amount is too small, the effect of the present invention will not be sufficient, and if this amount is too large, the reinforcing fibers will become stiff and easily cause bending fatigue. Become. The reinforcing fibers to which the second liquid has been applied are dried at 200 to 350°C, preferably at 250 to 300°C. The time required for drying is determined depending on the drying temperature, etc., but is usually 2 to 60 seconds.
It is appropriate to keep the moisture content at 0.5wt% or less. By completely drying in this way, the components contained in the first liquid and the second liquid contained in the mixed layer are firmly bonded and integrated, and no peeling occurs. Furthermore, since a surface layer is formed only from the components of the second liquid, the compatibility with the rubber matrix is improved. The reinforcing fibers obtained by the method of the present invention described above can be used as is for rubber reinforcement and have excellent effects, but adhesive fibers such as chloroprene rubber, chlorosulfonylated polyethylene, and hydrogenated nitrile rubber When used for reinforcing heat-resistant rubber with a small temperature, even better results can be obtained by further adding an overcoat liquid, as described below. As the overcoat liquid, one containing a halogen-containing polymer or an isocyanate gives particularly favorable results. As the isocyanate, methylene diphenyl isocyanate (MDI), toluene diisocyanate (TDI), triphenylmethane triisocyanate, naphthalene diisocyanate, etc. can be suitably used. Because isocyanate monomers have high volatility, they have relatively small molecular weights such as dimers,
Polyisocyanates with high reactivity can be suitably used. The preferred degree of polymerization is 2-10. As the halogen-containing polymer, chlorinated rubber, chloroprene, chlorinated polyethylene, chlorinated ethylene-propylene copolymer, chlorinated polyvinyl chloride, chlorosulfonylated polyethylene, etc. can be used, but chlorosulfonylated polyethylene is particularly preferred. gives a good result. It is appropriate that the ratio of isocyanate to halogen-containing polymer be 10 to 100:100; if the ratio of isocyanate is too large, flexural fatigue resistance and heat resistance will deteriorate. Furthermore, if the proportion of isocyanate is too small, adhesiveness tends to decrease. The concentration of the overcoat liquid (weight% of the total amount of isocyanate and halogen-containing polymer) is 3 to 3.
15 wt%, preferably 5 to 10 wt%, is appropriate; if this concentration is too high, the viscosity of the liquid will increase, making it easy to form unevenness, and if this concentration is too low, the amount of adhesion will decrease, making it difficult to maintain sufficient It becomes difficult to obtain an effect. A lead compound such as litharge, lead maleate, or lead phthalate can also be added to the overcoat liquid, which has the effect of improving water resistance. The amount of lead compounds in the overcoat liquid is 0.5~5wt
%, preferably 1 to 3 wt%. The amount of overcoat liquid applied is based on the reinforcing fibers.
A suitable content is 0.5 to 5 wt%, preferably 2 to 4 wt%. After applying the overcoat liquid, it is appropriate to dry it preferably at 120 to 200°C. In addition, the above-mentioned second liquid was applied to the reinforcing fibers and dried.
The S or Z twist (pre-twist) of about 0.5 to 4.0 per 2.54 cm (1 inch) is then further arranged to create a twist of about 0.5 to 3.0 per 2.54 cm, in the opposite direction to the pre-twist. It is desirable to twist (ply-twist) the yarn to form a yarn, and then apply an overcoat liquid to the yarn. There is no particular limitation on the type of rubber to be reinforced with the reinforcing fibers to which the overcoat liquid has been applied, but examples include blended compositions of Hypalon, nitrile rubber, and hydrogenated nitrile rubber, and extremely favorable results can be obtained. , reinforced rubber products such as timing belts with good heat resistance and durability can be obtained. (Function) The reinforcing fiber is the first material containing fluororesin latex.
Since the treatment with a liquid causes incomplete drying, a fluororesin layer is formed on the surface, resulting in an anti-friction effect that reduces friction between the fibers or between the fibers and the rubber matrix. Further, a second liquid containing a vinyl pyridine-styrene-butadiene terpolymer latex, rubber latex, and resorcinol-formaldehyde is applied onto the incompletely dried fluororesin layer.
Since a mixed layer of these and the fluororesin is formed, the two are evenly blended together, and when dried, they are firmly bonded and no peeling occurs. Furthermore, since a surface layer consisting only of the second liquid is formed on the surface, the compatibility with the rubber matrix is improved. (Example) Three glass fiber bundles made of 200 9μ glass fibers were arranged together and the first one was filled with polytetraethylene latex (AD-1 trade name, manufactured by Asahi Glass Co., Ltd., latex content 60wt%). After passing through the tank continuously, it was heated for 2 seconds in an oven maintained at 200°C. The amount of fluororesin attached was 16wt% of the reinforcing fibers, and the water content was 5wt% of the fluororesin. Then, it was passed through a second tank filled with a second liquid having the following composition, and then placed in an oven maintained at 250°C.
Heated for 20sec. The amount of the second liquid component attached is 3wt% based on the reinforcing fiber, and the water content is 0.02wt% based on the total resin solid content attached.
It was hot. Second liquid composition Vinylpyridine, styrene and butadiene
Vinylpyridine-styrene-butadiene terpolymer latex containing in a ratio of 15:15:70 (Pyratex, trade name, manufactured by Sumitomo Naugatatsu Co., Ltd., terpolymer content 41 wt%), 146.3 parts by weight,
SBR latex (J9049, trade name, latex content 49wt%), 81.6 parts by weight, 13.0wt addition condensate of resorcin and formaldehyde (resol)
% aqueous solution and 27.8 parts by weight of water, and further mixed 9 parts by weight of mineral oil emulsion (mineral oil content 55 wt%) as an anti-aging agent and 10 weight frames of ammonia water (concentration 18 wt%). What I did. Resin concentration 30wt%. Thirteen of the reinforcing fibers obtained in this way were arranged and given two S twists per 2.54 cm, and then treated with an overcoat liquid having the following composition. % deposit at 250℃
It was dried for 40 seconds to form a reinforcing fiber, and a test piece was prepared. Composition of overcoat liquid: 10 parts by weight of chlorosulfonylated polyethylene rubber composition, 5 parts by weight of polyisocyanate, and toluene were added to give a concentration of 10%. Rubber type Specifications of hydrogenated nitrile rubber test piece Automotive toothed belt Width 25.4mm The results of the adhesion test and bending test A and B of the above test piece are shown in the attached table. (Comparative example 1) The second liquid of the example was added to the same reinforcing fiber as the example.
The same test as in the example was conducted using a sample containing 19 wt% and heated to 250°C for 20 seconds. The results are shown in the attached table. (Comparative Example 2) In place of the second liquid in Comparative Example 1, the first liquid in Example was used. The results of the same tests as in the examples are shown in the attached table. (Comparative Example 3) A test was conducted under the same conditions as in the example except that drying after application of the first liquid was carried out at 250° C. for 30 seconds and the moisture content was 0.3 wt% or less. The results are shown in the attached table. 【table】

Claims (1)

[Claims] 1 After treating the fibers with the first liquid containing fluororesin latex, drying and reducing the moisture content to 2
~20wt%, and then treated with a second liquid containing a terpolymer latex of vinylpyridine-styrene-butadiene, rubber latex, and a water-soluble condensate of resorcinol-formaldehyde, and then dried. Law.