JPH0778206B2 - Adhesive of rubber and organic synthetic fiber - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adhesive of a nitrile group-containing highly saturated rubber and an organic synthetic fiber such as polyester fiber and polyamide fiber.

(Prior Art) A tire as a rubber product comprising rubber such as natural rubber, styrene-butadiene copolymer rubber or acrylonitrile-butadiene copolymer rubber (NBR), and organic synthetic fibers such as polyester fibers or polyamide fibers as reinforcing fibers,
There are belts, hoses, etc.

Conventionally, an adhesive composed of a styrene-butadiene-vinylpyridine copolymer rubber and a resorcin-formaldehyde resin has been used for bonding these fibers and rubber.
However, even if the above-mentioned conventional adhesive is used for bonding the nitrile group-containing highly saturated rubber excellent in oil resistance and heat resistance, which was developed as a rubber material for exhaust gas countermeasures for automobiles, to the above-mentioned conventional adhesive, In this case, sufficient adhesive strength cannot be obtained, and development of new adhesives is desired.

(Problems to be Solved by the Invention) Accordingly, an object of the present invention is to provide an adhesive which exhibits sufficient adhesive strength at room temperature and after heat aging in bonding a highly saturated rubber containing a nitrile group to an organic synthetic fiber. Especially.

(Means for Solving the Problems) According to the present invention, an adhesive agent for a nitrile group-containing highly saturated rubber composed of a nitrile group-containing highly saturated rubber latex having an iodine value of 120 or less and a resorcin-formaldehyde resin and an organic synthetic fiber. Will be provided.

The nitrile group-containing highly saturated rubber constituting the latex used in the present invention is a hydrogenated conjugated diene unit of an unsaturated nitrile-conjugated diene copolymer rubber; unsaturated nitrile-conjugated diene-ethylenically unsaturated monomer 3 A hydrogenated copolymer diene unit and a conjugated diene unit of this rubber; an unsaturated nitrile-ethylenically unsaturated monomer copolymer rubber can be mentioned. These nitrile group-containing highly saturated polymer rubbers can be obtained by using a usual polymerization method and a usual hydrogenation method, but it goes without saying that the method for producing the rubber is not particularly limited in the present invention.

The monomers used for producing the nitrile group-containing highly saturated rubber of the present invention are exemplified below.

Examples of unsaturated nitriles include acrylonitrile and methacrylonitrile, and examples of conjugated dienes include 1,3-butadiene, 2,3-dimethylbutadiene, isoprene, and 1,3-pentadiene. As the ethylenically unsaturated monomer, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid and salts thereof; methyl acrylate, ethyl acrylate, butyl acrylate,
Esters of said carboxylic acids such as 2-ethylhexyl acrylate; alkoxyalkyl esters of said unsaturated carboxylic acids such as methoxymethyl acrylate, ethoxyethyl acrylate, methoxyethoxyethyl acrylate; acrylamide, methacrylamide; N-methylol (meth) acrylamide , N, N′-dimethylol (meth) acrylamide, N-substituted (meth) acrylamides such as N-ethoxymethyl (meth) acrylamide; cyanomethyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, 1-cyanopropyl ( (Meth) acrylate, 2-ethyl-6-cyanohexyl (meth) acrylate, cyano-substituted alkyl ester of (meth) acrylic acid such as 3-cyanopropyl acrylate, vinyl pyridine, etc. It is included.

In the unsaturated nitrile-ethylenically unsaturated monomer-based copolymer rubber, a part of the unsaturated monomer is replaced with a non-conjugated diene such as vinyl norbornene, dicyclopentadiene and 1,4-hexadiene. It may be copolymerized.

The content of unsaturated nitrile units in nitrile group-containing highly saturated rubber is usually determined from the viewpoint of adhesiveness and familiarity with adherend rubber.
It is selected in the range of 10 to 60% by weight and is not particularly limited. Further, in order to obtain sufficient adhesive strength even after heat aging, the iodine value of the rubber is 120 or less, preferably 0 to 100.
Is the range.

The nitrile group-containing highly saturated rubber used in the present invention is specifically a hydrogenated product of butadiene-acrylonitrile copolymer rubber, isoprene-butadiene-acrylonitrile copolymer rubber, isoprene-acrylonitrile copolymer rubber, etc .; butadiene -Methyl acrylate-acrylonitrile copolymer rubber, butadiene-acrylic acid-
Acrylonitrile copolymer rubber, etc. and hydrogenated products thereof; butadiene-ethylene-acrylonitrile copolymer rubber, butyl acrylate-ethoxyethyl acrylate-vinyl chloroacetate-acrylonitrile copolymer rubber, butyl acrylate-ethoxyethyl acrylate-vinyl norbornene-acrylonitrile Examples thereof include copolymer rubber.

The iodine value of each component polymer of the present invention is a value determined according to JIS K0070.

The nitrile group-containing highly saturated rubber latex used in the present invention is produced by a known phase inversion method when the rubber is a hydrogenated rubber, and by an ordinary emulsion polymerization when it is not a hydrogenated rubber.

The phase inversion method is a method in which a solution of a nitrile group-containing highly saturated rubber and an emulsifier aqueous solution are mixed, the rubber is emulsified and dispersed as fine particles in water by vigorous stirring, and the solvent is further removed. A highly saturated rubber latex is obtained. As the nitrile group-containing highly saturated rubber solution at that time, the solution at the end of the polymerization and the hydrogenation reaction can be used as it is, or a concentrated or diluted solution can be used, or the solid rubber can be dissolved in a solvent. Can also be used. As the solvent, the rubber-soluble aromatic solvents such as benzene, toluene and xylene, halogenated hydrocarbon solvents such as dichloroethane and chloroform, ketones such as methyl ethyl ketone, acetone and tetrahydrofuran may be used alone or in combination. . The concentration of the nitrile group-containing highly saturated polymer rubber in the solution is usually in the range of 1 to 25% by weight. Usually as an emulsifier,
Fatty acids such as oleic acid and stearic acid, rosin acids, potassium salts such as alkylbenzene sulfonic acids and alkyl sulfates, sodium salts, and polyoxyethylene-based nonionic emulsifiers may be used alone or in combination.

The volume ratio of the nitrile group-containing highly saturated rubber solution and water is usually
It is in the range of 3: 1 to 1:20. As a stirrer for emulsifying and dispersing, various homomixers, ultrasonic emulsifiers and the like are used. The removal of the solvent from the emulsion is performed by a known method such as a steam stripping method.

The adhesive of the present invention is the above-mentioned nitrile group-containing highly saturated rubber latex blended with a resorcin-formaldehyde resin, which is conventionally used (for example, those disclosed in JP-A-55-142635). Can be used and is not particularly limited. Further, it may be used in combination with a compound such as a 2,6-bis (2,4-dihydroxyphenylmethyl) -4-chlorophenol composition which has been conventionally used for enhancing the adhesive strength.

As the adhesive of the present invention, a mixture of 10 to 180 parts by weight (dry weight) of resorcin-formaldehyde resin is used with respect to 100 parts by weight of the solid content of the rubber latex of the present invention.

Further, a part of the rubber latex of the present invention in the adhesive of the present invention is a styrene-butadiene copolymer rubber latex and a modified latex thereof, an acrylonitrile-butadiene copolymer rubber latex and a modified thereof, within a range not impairing the gist of the present invention. One or more of latex and natural rubber latex can be substituted.

Examples of the organic synthetic fibers used in the present invention include vinylon fibers; polyester fibers; polyamide fibers such as nylon and aramid (aromatic polyamide). These fibers are used in the form of woven fabric such as stable, filament, cord, rope and canvas.

The nitrile group-containing highly saturated rubber which is the adherend of these organic synthetic fibers used in the present invention has the same monomer unit in the nitrile group-containing highly saturated rubber which constitutes the latex of the present invention. The content of unsaturated nitrile unit is usually 10 to 60 from the viewpoint of oil resistance of the rubber product compounded with the fiber.
The iodine value is 120 or less, preferably 0 to 100, more preferably 0 to 80, from the viewpoint of heat resistance.

Adhesion of the rubber and the fiber using the adhesive of the present invention is prepared by adding a compounding agent such as a vulcanizing agent and a filler to the fiber and the rubber that have been heat treated after immersion treatment with the adhesive of the present invention. It is achieved by compounding with another rubber compound and then vulcanizing.

The conditions of the heat treatment of the fibers are not particularly limited in the present invention, and although there are some variations according to the type of the fibers, the temperature and time are sufficient to react and fix the RFL adhered by immersion, and usually, It is performed at 140-250 ℃ for several minutes.

Incidentally, depending on the type of fiber, it is usually possible to immerse the fiber in an isocyanate solution, an epoxy solution or a mixture thereof in advance and to carry out a drying treatment prior to the immersion in the treatment liquid. In this case, the drying temperature is preferably lower than the temperature of the subsequent heat treatment.

(Advantages of the Invention) Use of the adhesive of the present invention gives superior initial adhesive strength as compared with conventional adhesives, and, compared with the case of using conventional adhesives, the adhesive strength after heat aging is extremely remarkable. Since it can be improved, it can be used for manufacturing various belts such as a toothed conductive belt using an organic synthetic fiber as a tensile body, various belts such as V belts, pressure hoses, and freon hoses.

(Example) Hereinafter, the present invention will be described more specifically with reference to Examples. The parts and% in the examples and comparative examples are based on dry weight unless otherwise specified.

[Sample Preparation Example 1] (Preparation of Nitrile Group-Containing Highly Saturated Polymer Rubber) Emulsion Polymerized Acrylonitrile-Methyl Isobutyl Ketone
Putadiene copolymer rubber (NBR) and butadiene-putyl acrylate-acrylonitrile terpolymer rubber are dissolved and hydrogenated using a Pd-carbon catalyst to obtain hydrogenated NBR and hydrogenated acrylonitrile having iodine values shown in Table 1. A butadiene-butyl acrylate terpolymer rubber was prepared.

[Sample preparation example 2] (Preparation of latex) 24.6 g of the rubber sample shown in Table 1 was dissolved in 275.4 g of a toluene / dichloroethane (75/25% by volume) mixed solvent. The above rubber solution was poured into an aqueous emulsifier solution consisting of 1.2 g of potassium oleate, 1.2 g of potassium rosinate and 0.045 g of potassium hydride, and 300 g of water with stirring, and then in a greenhouse, TK-Homomixer (Made by Tokushu Kika Kogyo M Type) 10,000 rotations /
Vigorously stirred for 10 minutes. The solvent was removed from the obtained emulsion by steam stripping and then concentrated using an evaporator to obtain a latex having a solid content of about 30%. Further, the mixture was centrifuged at room temperature at 3,000 rpm for 15 minutes to remove excess emulsifier and concentrate. The solid content and pH of the obtained latex are shown in Table 2.

[Sample Preparation Example 3] A nitrile group-containing highly saturated rubber and a compounding agent were kneaded on a roll according to the compounding recipe shown in Table 3 to prepare a sheet of a rubber compound having a thickness of about 3 mm.

Example 1 Each latex of A to H described in Table 2 according to the formulation of Table 3 and resorcin-formalin (R
The solution (F) was mixed and a resorcin-formalin-latex (RFL) solution was prepared according to a conventional method.

A nylon fiber cord (nylon 6, structure 1260D / 2) was dipped in the above RFL solution and heat-treated at 200 ° C. for 2 minutes. The treated cord was pinched with a rubber compound (a) or (b) sheet of Sample Preparation Example 3, and a cord pull-out test (H test,
(According to ASTM D2138-72) was prepared. The test piece is
The rubber compound (a) was vulcanized at 160 ° C. for 20 minutes, and the rubber compound (b) was vulcanized at 170 ° C. for 20 minutes. The test piece was subjected to an air heat aging test at 120 ° C. for 2 weeks in order to see the cord pull-out strength after aging. The results of the initial adhesive strength and the adhesive strength after heat aging are shown in Table 5.

Example 2 Aramid fiber cord (Kevlar manufactured by DuPont, structure 15)
00D / 2,127T / m) is immersed in the pretreatment liquid of Table 6 at 220 ℃ for 2
After heat treatment for minutes, it was dipped in the RFL dipping solution prepared according to the formulation shown in Table 7 using the latex shown in Table 8 250
It heat-processed at 1 degreeC for 1 minute. The treated cord was sandwiched with a rubber compound sheet shown in Table 3 to prepare a sample for cord pull-out test in the same manner as in Example 1. The results of the pull-out test are shown in Table 8.

Example 3 Polyester fiber cord (polyethylene terephthalate, structure 1500D / 2) was dipped in the pretreatment liquid shown in Table 9 to 235 ° C.
After heat treatment for 2 minutes, it is immersed in the RFL solution of Example 1,
It heat-processed at 35 degreeC for 2 minutes.

The treated cord was sandwiched with the rubber compound (a) or (b) of Sample Preparation Example 3 to prepare a sample for cord pull-out test. The test piece was vulcanized at 160 ° C. for 20 minutes. The initial adhesive strength and the adhesive strength after heat aging were determined in the same manner as in Example 1. The results are shown in Table 10.

Claims (1)

[Claims] 1. An adhesive of a nitrile group-containing highly saturated rubber consisting of a nitrile group-containing highly saturated rubber latex having an iodine value of 120 or less and a resorcin-formaldehyde resin and an organic synthetic fiber.