JPH0456853B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to a rubber-to-fiber adhesive composition having improved adhesion and comprising a resorcinol-formaldehyde resin and a rubbery copolymer latex. (Prior art and problems to be solved by the invention) Conventionally, fibers have been immersed in an aqueous dispersion mainly composed of resorcinol-formaldehyde resin and latex in order to bond reinforcing fibers such as polyamide and polyester to rubber. I am using it.
As the latex, butadiene-vinylpyridine-styrene copolymer latex or a mixed latex of this latex with styrene-butadiene copolymer latex, natural rubber latex, or the like is generally used. Except for steel cord, nylon 6 and nylon 66 still make up the majority of raw materials for rubber reinforcing fibers in automobile tires, belts, hoses, etc. Polyester fibers are characterized by lower elongation than nylon, and are widely used as fibers for reinforcing rubber. However, depending on the usage conditions, the fibers deteriorate significantly, which limits their use. In other words, if the rubber of the molded product contains vulcanization accelerators such as thiuram-based, sulfenamide-based, or guanidine-based, amine-based anti-aging agents, or natural rubber, for example, long-term vulcanization during the manufacture of automobile tires may result. This is because polyester fibers have the disadvantage of deteriorating during the sulfurization process or during high-speed running of automobile tires, resulting in a significant drop in performance as reinforcing fibers. In order to improve this drawback, it is possible to improve the rubber compounding method by selecting preferable vulcanization accelerators and anti-aging agents, to improve the polyester fiber itself by reducing the amount of terminal carboxyl groups contained in the polyester fiber, or to improve the polyester fiber itself by reducing the amount of terminal carboxyl groups contained in the polyester fiber. Methods have been devised in which the compound is treated in advance with a compound containing a carboxyl group (for example, JP-A-55-166235), but this method limits the blending of the rubber and makes it impossible to obtain the desired physical properties of the vulcanized rubber. At the same time, the adhesive strength between the rubber and the fibers after long-term vulcanization (hereinafter referred to as heat-resistant adhesive strength) is not sufficiently improved, and although the method (2) improves the thermal deterioration of the fibers themselves, it does not improve the heat-resistant adhesive strength. Based on the knowledge of the present inventors, as a result of intensive research to develop an improved polymer latex used for adhesion between fibers and rubber, we found that the composition of the polymer is typically butadiene, vinylpyridine, and styrene. Surprisingly, the use of a latex obtained by copolymerizing ethylenically unsaturated acid monomers in addition to the above method has the ability to improve the heat-resistant adhesive strength of polyester fibers, which cannot be obtained by combining the above method with conventional adhesives. We have discovered that improvements can be made and have completed the present invention. The purpose of the present invention is to improve the heat-resistant adhesive strength of rubber products such as tires, belts, hoses, etc., especially when polyester fibers are used for reinforcement, and to improve the heat-resistant adhesive strength of rubber products such as tires, belts, hoses, etc. The object of the present invention is to provide a rubber and fiber adhesive composition that can be used in the same way as pyridine latex. (Means for Solving the Problems) The object of the present invention is to copolymerize (1) resorcinol-formaldehyde resin and (2) ethylenically unsaturated acid monomer in a copolymerized rubber in an amount of 0.1 to 25% by weight. This can be achieved by using an adhesive composition comprising a conjugated diene and a latex of vinylpyridine copolymer rubber. The copolymer rubber latex used in the present invention will be explained below. As the conjugated diene monomer, for example, 1,3-
Butadiene, 2-methyl-1,3-butadiene,
One or more aliphatic conjugated diene monomers such as 2,3-dimethyl-1,3-butadiene and halogen-substituted butadiene are used. The content of conjugated diene monomer in copolymer rubber is usually 45
~85% by weight, and outside this range the adhesive strength decreases. Preferably it is 60-75% by weight. As the vinylpyridine, 2-vinylpyridine is preferable, but it may be replaced with one or more of 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, 5-ethyl-2-vinylpyridine, etc. I can do it. The content of vinylpyridine monomer in the copolymer rubber is usually 10 to 35% by weight, and if it is out of this range, the adhesive strength decreases. Preferably it is 15 to 30% by weight. Ethylenically unsaturated acid monomers include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, butenetricarboxylic acid; itaconic acid monoethyl ester, fumaric acid monobutyl ester,
Monoalkyl esters of unsaturated dicarboxylic acids such as monobutyl maleate; sulfoethyl acrylate sodium salt, sulfopropyl methacrylate
1, such as Na salt, unsaturated sulfonic acid such as acrylamide propane sulfonic acid, or its alkali salt.
One species or two or more species may be used. The content of ethylenically unsaturated monomer in copolymer rubber is 0.1-25
If it is less than 0.1% by weight, the heat-resistant adhesive strength of polyester fibers will not be improved, and if it exceeds 25% by weight, the adhesive strength will decrease. Preferably 0.2-12% by weight
The content is more preferably 0.5 to 8% by weight.
Furthermore, if desired, other monomers copolymerizable with each of the above monomers may be copolymerized. Examples of such monomers include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t
- Aromatic vinyl compounds such as butylstyrene, 5-t-butyl-2-methylstyrene, monochlorostyrene, dichlorostyrene, monofluorostyrene, hydroxymethylstyrene, and aliphatic vinyl compounds such as ethylene, propylene, acrylonitrile, vinyl chloride, etc. are exemplified, and one or more of these can be copolymerized. The content in the copolymer is 30% by weight or less. In addition, in the present invention, in order to increase the initial adhesive strength (adhesive strength during short-time vulcanization), it is better to have a lower gel content of the copolymer rubber in the latex.
It is preferably less than % by weight (the measurement method is described in the Examples). The method for producing the latex of the present invention is not particularly limited, and it may be produced by one-stage polymerization by charging all the monomers to be used at once into a polymerization container, or by polymerizing some monomers and then producing the latex. It may be produced by a two-stage polymerization method, etc., in which monomers are added and polymerization is continued. The resorcinol-formaldehyde resin used in the present invention is a conventionally used resin (for example,
-142635) can be used, and there are no particular restrictions. Further, it may be used in combination with compounds such as 2,6-bis(2,4-dihydroxyphenylmethyl)-4-chlorophenol compositions, which have been conventionally used to increase adhesive strength. The adhesive composition of the present invention is usually a mixture of 10 to 40 parts by weight (dry weight) of a resorcinol-formaldehyde resin based on 100 parts by weight of the solid content of the copolymer rubber latex of the present invention. In addition, a part of the copolymer rubber latex of the present invention in the adhesive composition of the present invention is selected from styrene-butadiene copolymer rubber latex and its modified latex, acrylonitrile-butadiene copolymer rubber latex and its modified latex, natural rubber latex, etc. It can be replaced with one or more of the following. There are no particular restrictions on the method of using the adhesive composition of the present invention, and it can be applied in the same manner as known resorcinol-formaldehyde-polymer latex adhesives. Usually, the adhesive composition of the present invention is made into an aqueous solution of 10 to 30% by weight, and during the production of rubber products, fibers in a desired form are immersed, dried, and heat treated, and then molded together with an unvulcanized rubber compound. Fibers and rubber can be bonded together by vulcanization. Further, it is also possible to use fibers in a desired form coated with the adhesive composition of the present invention in advance. There are no particular restrictions on the fibers to which the adhesive composition of the present invention can be applied, including rayon fibers, polyester fibers,
Can be used for polyamide fibers, aramid fibers, etc. These fibers may be in any form such as woven fabric, cord, or thread. The rubber-fiber adhesive of the present invention provides the same adhesive strength as conventional adhesives using the same formulation and has improved heat-resistant adhesive strength, especially with polyester fibers. It can be used to manufacture tires, belts, hoses, etc. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples. Note that all parts and percentages in the examples represent parts and percentages by weight on a dry basis. Example of latex production Table 1: In an autoclave with a stirrer, 150 parts of water, 5 parts of polyoxyethylene lauryl ether (Emulgen 147 manufactured by Kao Soap), 0.05 part of sodium ethylenediaminetetraacetate, 0.5 part of t-dodecylmercaptan and 0.3 part of potassium persulfate. Add a total of 100 parts of the listed monomers and mix by rotation.
The reaction was carried out at ℃. When the polymerization conversion rate reaches 50%, t
- 0.5 part of dodecyl mercaptan was added. When the polymerization conversion rate reached 95%, 0.05 part of hydroquinone was added to stop the reaction, and unreacted monomers were removed under reduced pressure to produce latexes A to O. The content of the polymer insoluble in tetrahydrofuran (hereinafter referred to as gel content) in these latexes was all 20% by weight or less. Next, the raw materials were charged into an autoclave equipped with a stirrer and reacted in the same manner as for producing Latex G, but a latex was produced in which the amount of t-dodecyl mercaptan added was reduced from 0.5 part to 0.2 part at a polymerization conversion rate of 50%. . This is called latex P. The gel content of Latex P was 37%. Next, raw materials were charged into an autoclave equipped with a stirrer and reacted in the same manner as for producing Latex G, but a latex was produced in which the amount of t-dodecyl mercaptan was reduced from 0.5 parts to 0 parts at a polymerization conversion of 50%. This is called latex Q. The gel content of Latex Q was 45%. The gel content of the polymer in the latex was measured by the following method. Add 100g of ethanol to a glass beaker and mix with a magnetic stirrer while adding about 10g of latex. After stirring for 5 minutes to solidify, discard the ethanol and add 100 g of distilled water to wash the polymer while stirring. After washing with distilled water three times, the polymer was dried in a vacuum dryer set at 50°C for 2 hours. Next, 0.2 g of the dried polymer and 100 g of tetrahydrofuran were placed in a glass beaker, and the mixture was left at room temperature for one day. Thereafter, it was passed through an 80-mesh stainless steel wire mesh, dried together with the wire mesh, and then weighed to determine the weight of the tetrahydrofuran insoluble matter. Calculate the gel content using the following formula:

[Table] Gel content (%) = Dry weight of tetrahydrofuran insoluble matter (g) / 0.2 x 100 Example 1 16.6 parts of resorcinol, formalin aqueous solution (37
% concentration) 14.6 parts, 1.3 parts of sodium hydroxide in water
The solution was dissolved in 333.5 parts and reacted at 25°C for 2 hours with stirring. Next, add the latex listed in Table 3 into this.
100 parts were added thereto and the mixture was reacted at 25° C. for 20 hours with stirring.
Next is Vulkabond E [ICI vulnax product]
Vulcabond E: 2,6-bis(2,4-dihydroxyphenylmethyl)-4-chlorophenol polymer ammonia aqueous solution (approximately 20% concentration)]
Part was added. After adjusting this aqueous solution to a solid content concentration of 15%, polyester tire cord (1500D/
2) was subjected to immersion treatment. After the immersion treatment, heat treatment was performed at 240°C for 1 minute. This treated polyester tire cord was sandwiched between natural rubber compounds prepared according to the formulation shown in Table 2, and press vulcanized. The adhesion between the tire cord and rubber was evaluated using the T adhesion test method (measurement temperature: 20° C., relative humidity: 65%, 24-wire pull-out test). The results are shown in Table 3. Table 2 Rubber compounding formula Natural rubber 100 parts Zinc white 5〃 Stearic acid 2〃 Sulfur 25〃 FEF carbon black 45〃 Process oil 5〃 N-oxydiethylene-2-benzothiazylsulfenamide 1〃 2,2, 4-trimethyl-1,2-dihydroquinoline polymer 0.2〃

【table】

[Table] From the results in Table 3, the use of the adhesive of the present invention significantly improves the adhesive strength (heat-resistant adhesive strength) between polyester fiber and rubber during high-temperature, long-term vulcanization (vulcanization condition 2). It can be seen that the adhesive strength (initial adhesive strength) during short-time vulcanization (vulcanization condition 1) is equivalent to that when a conventional adhesive using Latex 1 or 2 is used. Example 2 Latex D, E, F, G, H, I, J, K,
The adhesive strength of L was measured in the same manner as in Example 1. The results are shown in Table 4.

[Table] Example 3 The adhesive strength of latexes M, N, O, P, and Q was measured in the same manner as in Example 1. The results are shown in Table 5.

[Table] Example 4 Nylon 6 tire cord (1260D/2) and aramid fiber (DuPont KEVLAR, 1500D/
Table 6 shows the adhesive strength between 2) and natural rubber (the formulation is the same as in Table 2). Since there is no particular need to improve the heat-resistant adhesive strength of these fibers, the initial adhesive strength was compared with that when a conventional adhesive was used. Adhesives were prepared and processed using the latexes shown in Table 6 as follows. (For nylon 6 tire cord) 11 parts resorcinol, formalin aqueous solution (37%
Concentration) 16.2 parts, 0.3 parts of sodium hydroxide and 238.5 parts of water
and reacted at 25° C. for 6 hours with stirring.
Next, 100 parts of latex (see Table 2) was added thereto, and the mixture was reacted at 25° C. for 20 hours with stirring. After adjusting the solid content concentration of this aqueous solution to 15%, a nylon 6 tire cord (1260D/2) was immersed using a test single cord dipping machine. After dipping, heat treatment was performed at 200°C for 1 minute. The adhesion test was conducted in the same manner as in Example 1. (For aramid fibers) Denacol EX-313 [manufactured by Nagase Sangyo Co., Ltd.: Glycerol polyglycidyl ether (epoxy equivalent
141)] 222 parts, sodium hydroxide (10% aqueous solution)
Aramid fiber (Kevlar 1500D/2 manufactured by Dupont) was tested in a mixture of 0.28 parts of "AEROSOL" OT (anionic surfactant manufactured by Nippon Aerosil Co., Ltd.; 5% aqueous solution of sodium dioctyl sulfosuccinate), 0.56 parts, and 96.94 parts of water. The sample was immersed using a single-cord dipping machine and heat-treated at 240°C for 1 minute. Subsequently, it was immersed in the aqueous resorcinol-formaldehyde latex solution used in Example 2, and heat-treated at 240°C for 1 minute. The adhesion test was conducted in the same manner as in Example 1.

【table】

[Table] The results show that the adhesive of the present invention can be used in the same way as the conventional adhesive of the comparative example. Example 5 Instead of 100 parts of latex A, latex
90 parts of A and styrene-butadiene copolymer latex (product name: LX110 manufactured by Nippon Zeon Co., Ltd.; solid content: 40.5
%) mixed latex (Latex R) with 10 parts,
Example 1 except that a mixed latex (Latex S) of 90 parts of Latex A and 10 parts of carboxy-modified styrene-butadiene copolymer latex (trade name LX426, manufactured by Nippon Zeon Co., Ltd.; solid content 50%) was used. Adhesive strength was measured in the same manner as above. When Latex R was used, the adhesive strength was 14.4 kg/cm under vulcanization conditions 1 and 12.6 kg/cm under vulcanization conditions 2. Also, when using Latex E, the adhesive strength was 14.2 kg/cm under vulcanization condition 1 and 14.2 kg/cm under vulcanization condition 2.
It was 12.5Kg/cm.

Claims (1)

[Scope of Claims] 1. A resorcinol-formaldehyde resin; 2. A latex of a conjugated diene-vinylpyridine copolymer rubber obtained by copolymerizing 0.1 to 25% by weight of an ethylenically unsaturated acid monomer into a copolymer rubber. A rubber and fiber adhesive composition comprising: