JPH048545B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an overcoat liquid used in the production of rubber reinforcing fibers. [Prior Art] Reinforcing fibers such as glass fiber yarns are widely used to increase the strength of rubber products such as rubber belts and tires. Rubber products such as rubber belts are subjected to repeated bending stress, resulting in bending fatigue, resulting in a decrease in performance, and peeling between the reinforcing material and the rubber matrix is likely to occur. 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, various processing agents have been proposed, such as a processing agent using a combination of a vinylpyridine-styrene-butadiene terpolymer latex and a water-soluble condensate of resorcinol and formalin, or a processing agent containing rubber latex (Japanese Unexamined Patent Application Publication No. 1983-1999). (See No. 114551). Furthermore, a treatment liquid containing a polyisocyanate, a polynitroso aromatic compound, and an acidic halogen-containing polymer has also been proposed (see Japanese Patent Application Laid-Open No. 14546/1983). Further, a first liquid (RFT liquid) containing a water-soluble condensate of resorcin formaldehyde and rubber latex is applied to the rubber reinforcing fibers to form a first layer containing the resorcin formaldehyde condensate and rubber on the fibers, and then the rubber It is also known to form a second layer containing isocyanate and rubber by treating with an overcoat liquid containing isocyanate (see JP-A-49-14546). [Problems to be Solved by the Invention] Conventional processing agents have the following problems. (1) Sufficient adhesive strength cannot be obtained. (2) It is difficult to obtain rubber products with sufficient bending strength. Recently, with the rise in temperature near automobile engines, heat-resistant rubbers such as chlorosulfonylated polyethylene and hydrogenated nitrile rubber have come to be used as rubber for timing belts. Since such heat-resistant rubber has lower adhesion than ordinary rubber, the above-mentioned drawbacks tend to be greater than that of ordinary rubber. Treat the rubber reinforcing fibers with RFL liquid, then
Although the above-mentioned problems can be solved to some extent by treating with an overcoat liquid containing rubber and isocyanate, this method has the following problems. (1) Adhesive strength decreases over time. (2) In order to obtain sufficient effects, it is necessary to use a large amount of isocyanate; increasing the amount of isocyanate deteriorates the stability of the solution, and it is necessary to adjust the overcoat solution in small amounts each time it is used. . (3) The interfacial adhesion between the RFL layer (first layer) and the overcoat liquid (second layer) is poor, and peeling easily occurs between the first and second layers. The present invention solves the problems of the prior art described above,
Even when used under conditions of repeated bending stress, the adhesive strength does not decrease over time, and large amounts of isocyanate are not required.
An overcoat liquid that has sufficient adhesion between the RFL layer and the overcoat layer so that it does not cause delamination or deteriorate in performance even after long-term storage, and rubber reinforcing fibers treated with such an overcoat liquid. is intended to provide. [Means for Solving the Problems] In order to achieve the above object, in the present invention, in a rubber reinforcing fiber, methacrylate is added on a first layer containing a resorcin formaldehyde condensate and rubber latex formed on the fiber. acid salt,
or using rubber reinforcing fibers with a second layer comprising an acrylate, an isocyanate, and a halogen-containing polymer, and a first layer comprising a water-soluble condensate of resorcinol formaldehyde and a rubber latex.
An overcoat solution containing a methacrylate or acrylate, an isocyanate, and a halogen-containing polymer is used in an overcoat solution for treating the solution-treated rubber reinforcing fibers. Next, the present invention will be explained in more detail. A water-soluble condensate of resorcin formaldehyde (hereinafter simply referred to as a condensate) is a resorcin and formaldehyde rich in oxymethyl groups obtained by reacting resorcin and formaldehyde in the presence of an alkaline catalyst such as an alkali hydroxide, ammonia, or an amine. 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. As the rubber latex used in the first liquid, a relatively low weight latex used as a treatment agent for rubber reinforcing fibers can be suitably used, and there is no limitation, but in particular, butadiene rubber latex, vinylpyridine-styrene- Among the butadiene terpolymer latexes (hereinafter referred to as terpolymer latexes), terpolymer latexes are preferred. Butadiene rubber latexes include 0700 (trade name, Nippon Gosei Rubber Co., Ltd.) and Niipl LX111 (trade name, Nippon Zeon Co., Ltd.), and terpolymer latexes include vinylpyridine, styrene, and butadiene in a weight ratio of 10 to 10. 20:10 to 20:60 to 80 is particularly suitable;
Nipol 2518FS (trade name, manufactured by Nippon Zeon) etc. can be suitably used. Furthermore, it is more effective to use a combination of latex and terpolymer latex. In this case, the ratio of latex to the total amount of terpolymer latex and latex in the first liquid (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 of Note that all of the above ratios are based on solid content. The concentration of the above-mentioned mixture (the first liquid of the present invention), that is, the terpolymer latex, latex,
The weight percentage of the total amount of condensate is 10-50%, preferably
The amount of the first liquid applied to the reinforcing fibers is preferably 12 to 25 wt%, preferably 16 to 22 wt% of the weight of the fibers as a solid content. Incidentally, a latex stabilizer, anti-aging agent, etc. may be added to the first liquid as necessary. Next, the overcoat liquid will be explained. Suitably, methacrylates or acrylates, zinc methacrylate, lead methacrylate, aluminum methacrylate, silver methacrylate are used and suspended in the overcoat solution. Similar metal salts of acrylic acid can also be used. The amount of methacrylate or acrylate that should be suspended in the overcoat liquid is 3 to 0.001 wt%,
A suitable content is preferably 1.5 to 0.05 wt%. If this amount is too small, the effect of the present invention will not be sufficient, and if this amount is too large, the effect will not increase much and it is not economical. As the halogen-containing polymer, chlorinated rubber, chloroprene, chlorinated polyethylene, chlorinated ethylene-propylene copolymer, chlorinated polyvinyl chloride, chlorosulfonated polyethylene, etc. can be used, but chlorosulfonated polyethylene has particularly favorable results. give. Suitable chlorosulfonated polyethylene (CSM) latexes have a chlorine content of 20 to 40 wt%, preferably 25 to 35 wt%, and a S content of 0.5 to 2.0 wt%, preferably 1.1 to 1.4 wt%. Therefore, raw rubber having a Mooney viscosity of 30 to 95 can be suitably used. Further, the amount of the halogen-containing polymer in the overcoat liquid is suitably 1 to 10 wt%, preferably 2 to 5 wt% in terms of solid content. If this amount is too small, the effect of the present invention will not be sufficient, and if this amount is too large, the adhesive strength will tend to decrease. Isocyanate is added to the overcoat liquid. The amount of isocyanate is suitably 0.5 to 2.0 wt%, preferably 1 to 1.5 wt%, and can improve adhesion. The amount of isocyanate is sufficient to be about 50% of that of conventional technology, and there is no deterioration in bending fatigue or heat resistance that would occur if too much isocyanate is used, and the stability of the overcoat liquid is increased. do. The total weight percent of isocyanate and halogen-containing polymer in the overcoat liquid is 3 to 15 wt.
%, preferably 5 to 10 wt%,
If this concentration is too high, the viscosity of the liquid will increase,
Unevenness tends to occur, and if this concentration is too low, the amount of adhesion decreases, making it impossible to obtain a sufficient effect. Furthermore, by incorporating a vulcanizing agent into the overcoat liquid, the adhesion can be further improved and more favorable results can be obtained. Polynitroso aromatic compound A as a vulcanizing agent
(e.g. p-dinitrosobenzene), tetrachlorobenzoxon, poly p-dinitrosobenzene,
Examples include P,P'-dibenzoyl, benzoquinone dioxime, and p-benzoquinone oxime,
Particularly preferred are tetrachlorobenzoxon, polyp-dinitrosobenzene, p,p'-dibenzoylbenzoquinone dioxime, and p-benzoquinone dioxime. The amount of vulcanizing agent in the overcoat liquid is 0.3~3wt
%, preferably about 0.6 to 2.5 wt%; if this amount is too small, the effect will not be sufficient and separation will easily occur between the first liquid layer and the second liquid layer. Moreover, if this amount is too large, peeling between the rubber matrix and the second liquid layer tends to occur. 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%. Although there are no particular limitations on the reinforcing fibers to be treated by the method of the present invention, it is practical to use glass fibers. For example, glass fibers with a thickness of 9 μm that are bundled with a sizing agent and about 200 glass fibers can be suitably used. Arrange three such reinforcing fibers and add the first
The solution is applied in an amount of 12 to 25 wt%, preferably 16 to 22 wt%, according to a conventional method. After applying the first liquid, preferably after sufficiently drying,
Apply overcoat liquid according to the usual method. It is desirable to dry the first liquid at a temperature of 200 to 350°C. 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 second liquid, preferably 120~
Dry at 200°C. In addition, 2.54
After applying S or Z twist (pre-twist) of about 0.5 to 4.0 per cm (1 inch), pull together about 2 to 13 more strands and twist in the opposite direction to the pre-twist, about 0.5 to 3.0 per 2.54 cm. It is desirable to give yarn (ply twist) and apply an overcoat liquid to this yarn. There is no particular limitation on the type of rubber to be reinforced with the reinforcing fibers to which the treatment agent of the present invention has been applied, but examples include Hypalon, nitrile rubber, hydrogenated nitrile rubber, etc.
Extremely favorable results can be obtained, and rubber products such as timing belts with good heat resistance and durability can be obtained. [Function] A second layer containing a methacrylate or acrylate, an isocyanate, and a halogen-containing polymer is formed on the first layer containing a resorcin formaldehyde condensate and rubber latex formed on the fiber as a rubber reinforcing fiber. A methacrylate or acrylate salt, By using an overcoat liquid containing isocyanate and halogen-containing polymer, the adhesive strength between the rubber (matrix rubber) and reinforcing fibers is increased.
Even when used under conditions subject to repeated stress, it prevents deterioration over time, increases the interfacial adhesion between the RFL layer and the overcoat layer to prevent peeling, and furthermore, the use of isocyanate The amount of isocyanate is reduced to prevent deterioration of bending fatigue properties and heat resistance caused by excessive use of isocyanate. It also prevents performance deterioration due to changes in the overcoat liquid itself over time. [Example] Vinylpyridine, styrene and butadiene
65 parts by weight of vinylpyridine-styrene-butadiene terpolymer latex (Pyratex, trade name, manufactured by Sumitomo Naugatatsu Co., Ltd., terpolymer content 41wt%) containing a ratio of 15:15:70, butadiene latex (0700, Product name, Japan Synthetic Rubber Co., Ltd., 8 parts by weight of butadiene content (57 wt%), 20 wt% of an addition condensate of resorcinol and formaldehyde (resol) is added to a mixture of 15 parts by weight and 12 parts by weight of water, and further anti-aging. A first liquid was obtained by adding 1 part by weight of a mineral oil emulsion (mineral oil content: 55 wt%) and 1 part by weight of aqueous ammonia (concentration: 18 wt%) as agents. 0.8 parts by weight of zinc methacrylate, 6 parts by weight of chlorosulfonated polyethylene (Hypalon 40, trade name, manufactured by Showa Neoprene Co., Ltd.), polyisocyanate (MR-200, trade name, manufactured by Nippon Polyurethane Co., Ltd.)
1.1 parts by weight, 1.5 parts by weight of p,p'-dibenzoylbenzoquinone dioxime (vulcanizing agent), and doluene were added to obtain an overcoat liquid having a concentration of 10 wt%. The first liquid was applied to three glass fiber bundles, each consisting of 200 9μ glass fibers, in a conventional manner (solid content: 17 wt%). After drying at 250°C for 1 minute, this glass fiber bundle was given 4.0 Z twists (first twist) per 2.54 cm, and the fiber bundle that had been given this first twist was further twisted.
The second liquid was applied to the 13 strands that had been twisted 2.1 times per 2.54 cm (first twist) (solid content 3
%). This was dried at 130°C for 1 minute and used as a reinforcing fiber to prepare a test piece. Rubber type A: 100 parts by weight of hydrogenated nitrile rubber: 40 parts by weight of carbon black, 5 parts by weight of zinc white, 1 part by weight of stearic acid, 2 parts by weight of anti-aging agent, 3 parts by weight of vulcanization accelerator, 5 parts by weight of plasticizer. A combination of parts. B: Hypalon rubber is used in place of the hydrogenated nitrile rubber in A above. Preparation of test piece The following test piece was prepared using the rubber having the composition A or B above. Test piece 1 Two of the above reinforcing fibers were sandwiched between rubber sheets with a thickness of 1 mm, a width of 5 mm, and a length of 300 mm, pressed, and heated at 150°C.
Then, vulcanize for 20 minutes. Test piece 2 The above reinforcing fibers were arranged without gaps between rubber sheets with a thickness of 3 mm, width of 25.4 mm, and length of 100 mm, pressed, and vulcanized at 150°C for 20 minutes. The tensile strength of this test piece and this test piece 1
After being left in an oven at 120°C for 24 hours, the tensile strength of test piece 1 was measured using an MIT tester after applying bending stress 3000 times. This test piece 2 and the test piece after being left in hot water at 100℃ for 1 hour were measured using an autograph at 50 mm/
The adhesive force was measured by peeling at a pulling speed of min. The above test results are shown in the attached table. [Comparative Example] The same experiment was conducted using an overcoat liquid having the following composition instead of the overcoat liquid of the above example (Comparative Examples 1, 2, and 3). A similar experiment was also conducted in the case where the first liquid of the example was used and no overcoat liquid was applied at all (Comparative Example 4). The results of these experiments are shown in the attached table. Composition of overcoat liquid Comparative example 1 Comparative example 2 Comparative example 3 CSM 6.0 4.8 7.2 Isocyanate 1.1 4.8 2.4 Vulcanizing agent 1.5

[Table] Furthermore, the pot life of the overcoat liquid of the present invention was about 10 times that of the overcoat liquids of Comparative Examples 1 to 3. [Effects of the Invention] Even when used for a long time under conditions that provide repeated bending strength, the adhesive strength decreases little, and even when chlorosulfonated polyethylene or hydrogenated matrix rubber is used, it has a large adhesive strength. By reducing the amount of isocyanate used, it is possible to prevent deterioration of bending fatigue resistance and heat resistance. The overcoat liquid can be stored for a long time, and no peeling occurs between the first layer and the overcoat layer.

Claims (1)

[Claims] 1. In a rubber reinforcing fiber, a methacrylate,
Or a rubber reinforcing fiber formed with a second layer containing an acrylate, an isocyanate, and a halogen-containing polymer. 2. The rubber reinforcing fiber according to claim 1, wherein the halogen-containing polymer is chlorosulfonated polyethylene. 3. The rubber reinforcing fiber according to claim 2, wherein the chlorine content in the chlorosulfonated polyethylene is 20 to 40 wt%, and the S content in the sulfon group is 0.5 to 2.0 wt%. 4. The rubber reinforcing fiber according to claim 2 or 3, wherein the Mooney viscosity of the chlorosulfonated polyethylene raw rubber is 30 to 95. 5. The rubber reinforcing fiber according to claim 1, 2, 3 or 4, wherein the second layer further contains a vulcanizing agent and a lead compound. 6 Vulcanizing agent is tetrachlorobenzoquinone, polyp
-dinitrosobenzene, p,p'-dibenzoylbenzoquinone dioxime, or p-benzoquinone dioxime. 7 In an overcoat liquid for treating rubber reinforcing fibers treated with a first liquid containing a water-soluble condensate of resorcinol formaldehyde and rubber latex, an overcoat containing a methacrylate or an acrylate, an isocyanate, and a halogen-containing polymer. liquid. 8. The overcoat liquid according to claim 7, wherein the halogen-containing polymer is chlorosulfonated polyethylene. 9. The overcoat liquid according to claim 8, wherein the chlorine content in the chlorosulfonated polyethylene is 20 to 40 wt%, and the S content in the sulfon group is 0.5 to 2.0 wt%. 10. The overcoat liquid according to claim 8 or 9, wherein the Mooney viscosity of the chlorosulfonated polyethylene raw rubber is 30 to 95. 11. The overcoat liquid according to claim 7, 8, 9 or 10, wherein the overcoat liquid further contains a vulcanizing agent and a lead compound. 12. The overcoat liquid according to claim 11, wherein the vulcanizing agent is tetrachlorobenzoquinone, polyp-dinitrosobenzene, p,p'-dibenzoylbenzoquinone dioxime, or p-benzoquinone dioxime.