JPH0291135A - Highly saturated polymer rubber latex containing nitrile group and adhesive for bonding same polymer with polyester fiber - Google Patents

Abstract

PURPOSE:To obtain the title adhesive with excellent initial adhesiveness and adhesiveness after heat aging by mixing the title latex wherein the amt. of a specified metal and that of ions except metallic ions are each below a specified value with a resorcinol-formaldehyde resin. CONSTITUTION:The title adhesive is obtd. by mixing a highly satd. polymer rubber latex with an iodine value of 120 or smaller wherein the amt. of metals except alkali metals in the solid component of the latex is 200ppm or lower and the amt. of ions except metallic ions measured by means of ion chromatography is 100ppm or lower (e.g., a rubber consisting of a nitrile group- contg. highly satd. rubber obtd. by hydrogenating conjugated diene units of an unsatd. nitrile-conjugated diene copolymer rubber) with a resorcinol- formaldehyde resin. When it is used for vulcanization adhesion of a nitrile group-contg. highly satd. polymer rubber with a polyester fiber, excellent initial adhesive force and adhesive force after heat aging can be obtd. Therefore, it is possible to use the title adhesive for manufacturing a toothed transmission belt, a V-belt, a pressure hose, etc., using this fiber as a tension member.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a highly saturated composite rubber latex containing nitrile groups and an adhesive between rubber and polyester fiber using the latex.

(Prior art) Natural rubber latex and synthetic rubber latex have been used in various fields, one of which is as an adhesive between rubber and reinforcing organic fibers such as polyester fibers and polyamide fibers. It has its uses.

If the rubber is a conventional rubber such as natural rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber (NBR), styrene-butadiene-vinylpyridine copolymer rubber latex (vP latex) and resorcinol-formaldehyde resin. Adhesives consisting of are used, and sufficient adhesive strength has been obtained.

However, hydrogenated NBR, which was developed as a rubber for automobile exhaust gas control, has an extremely low content of unsaturated bonds in its molecular chain, and adhesives using the above-mentioned VP latex cannot combine hydrogenated NBR and reinforcing organic fibers. The adhesive strength is insufficient. The present inventors proposed the use of hydrogenated NBR latex as one of the improvement methods (Patent Application No. 62-467
No. 65). In this method, emulsion polymerized NBR is hydrogenated,
Next, an adhesive made of hydrogenated NBR latex latexed by a phase inversion method and resorcinol-formaldehyde resin is used. Although the initial adhesive strength at room temperature is at a level that is satisfactory for both polyester fibers and polyamide fibers, Adhesive strength after aging is insufficient for polyester fibers, and further improvement is required.

(Problems to be Solved by the Invention) As a result of various studies on the causes of the above-mentioned problems, the present inventors have decided to use hydrogenated NBR latex as an adhesive latex in vulcanization adhesion between polyester fiber and hydrogenated NBR. In some cases, unlike the use of conventional polymer latex, the content of specific metals and the content of ions other than metal ions in the solid content of the latex may be different after heat aging of polyester fibers and hydrogenated NBR. It was discovered that this has an effect on adhesive strength, and based on this knowledge, the present invention was completed.

Accordingly, an object of the present invention is to provide a novel nitrile group-containing highly saturated composite rubber latex and an adhesive using the same for bonding a nitrile group-containing highly saturated composite rubber and polyester fibers.

(Means for Solving the Problems) According to the present invention, there is provided a latex of a highly saturated composite rubber containing nitrile groups having an iodine value of 120 or less, in which metals other than alkali metals in the solid content of the latex are provided. The content of ions is 200 ppm or less, and the content of ions other than metal ions measured by ion chromatography is 1100 ppm or less.
A highly saturated composite rubber latex containing nitrile groups, characterized in that the polymer rubber latex contains a nitrile group and a resorcinol-formaldehyde resin for vulcanization bonding the highly saturated composite rubber containing nitrile groups and polyester fibers. An adhesive is provided comprising:

The nitrile group-containing highly saturated rubber constituting the latex of the present invention is obtained by hydrogenating the conjugated diene unit of an unsaturated nitrile-conjugated diene copolymer rubber; Polymerized rubbers and unsaturated nitrile-ethylenically unsaturated heptamer copolymer rubbers obtained by hydrogenating the conjugated diene units of these rubbers may be mentioned. These nitrile group-containing highly saturated polymer rubbers can be obtained by using conventional polymerization techniques and conventional hydrogenation methods.

The monomers used to produce the nitrile group-containing highly saturated rubber of the present invention are illustrated 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-dimethyl-butadiene.
- Pentagene, etc. Ethylenically unsaturated monomers include unsaturated carboxylic acids and their salts such as acrylic acid, methacrylic acid, itaconic acid, and maleic acid; methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, trifluoroethyl acrylate, and tetrafluoroethyl acrylate. esters of said carboxylic acids, such as fluoropropyl acrylate; alkoxyalkyl esters of said unsaturated carboxylic acids, such as methoxymethyl acrylate, ethoxyethyl acrylate, methoxyethoxyethyl acrylate; acrylamide, methacrylamide; N-methylol (meth)acrylamide, N-substituted (meth)acrylamides such as N,N'-dimethylol (meth)acrylamide, N-ethoxymethyl (meth)acrylamide; cyanomethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 1-cyanopropyl (meth)acrylate; ) acrylate, 2-
Ethyl-6-diatsuhexyl (meth)acrylate, 3
- (Meth)acrylic acid cyano-substituted alkyl esters such as cyanopropyl acrylate, fluoroalkyl vinyl ethers such as fluoroethyl vinyl ether, vinylpyridine, and the like.

In the unsaturated nitrile-ethylenically unsaturated monomer copolymer rubber, a portion of the unsaturated monomer is replaced with a nonconjugated diene such as vinylnorbornene, dicyclopentadiene, or 1,4-hexadiene. It may also be copolymerized.

When the above monomers are copolymerized using a normal polymerization method and a large amount of conjugated diene is used, the conjugated diene units in the obtained copolymer can be hydrogenated using a normal hydrogenation method to contain nitrile groups. A highly saturated composite rubber is produced.

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

The highly saturated polymer rubber latex containing nitrile groups of the present invention is produced by a commonly known phase inversion method when the rubber is a hydrogenated rubber, and by conventional emulsion polymerization when it is not a hydrogenated rubber.

The nitrile group-containing highly saturated composite rubber latex of the present invention has a solid content of metals other than alkali metals of 200%.
It is characterized in that the content of ions other than metal ions measured by ion chromatography is 1100 pp or less. In the present invention, there are no particular limitations on the method for adjusting the metal and ion contents to the above ranges, but the following methods are exemplified.

A. When the polymer rubber latex is a hydrogenated rubber latex, (1) hydrogenation is performed after refining the emulsion polymerized rubber to reduce the metal content and ion content (2) emulsification. Hydrogenate the polymerized rubber and then refine the hydrogenated rubber (3) Hydrogenate the emulsion polymerized rubber using as little emulsifier as possible [If necessary, combine (2) and (3)]
(4) Hydrogenate the coagulated emulsion polymerized rubber using a polymer coagulant as a coagulant [combining (1) to (3) if necessary] (5) Using a nonionic surfactant as an emulsifier An emulsion polymerized rubber (disclosed in JP-A No. 61-51004), which is obtained by carrying out emulsion polymerization and coagulating latex by heating the latex to a temperature other than the clouding point of the surfactant without using a coagulant, is hydrogenated [ If necessary, combine (1) and (2)) (6) Hydrogenate the solution polymerized rubber [if necessary, perform (1).

(2) Purification] (7) Hydrogenated rubber prepared by hydrogenating bulk polymerized rubber or the like is converted into latex by a phase inversion method. The water and emulsifier used in this case preferably do not contain the metal or ion, or contain as little as possible.

B. When using emulsion polymerized rubber latex as it is as the polymer rubber latex, for example, use a nonionic surfactant as an emulsifier, use a substance that does not contain the metal as a redox polymerization initiator, etc. Examples include emulsion polymerized rubber latex obtained by emulsion polymerization by the method described in the following.

In order to increase the initial adhesive strength and the adhesive strength after heat aging when a nitrile group-containing highly saturated composite rubber and polyester fiber are vulcanized and bonded using an adhesive consisting of the polymer rubber latex and resorcin formaldehyde resin, Regardless of which method is used, the content of metals other than alkali metals in the solid content of the highly saturated nitrile group-containing composite rubber latex of the present invention is 200 pp+ or less, preferably 180 pp.
m or less, and the total ion content of cations and anions other than metal ions measured by ion chromatography is 1100 ppm or less, preferably 80 ppm or less.

In addition, the polymer rubber constituting the highly saturated nitrile group-containing composite rubber latex conforms to JIS K 0070 in order to increase the initial adhesive strength during vulcanization adhesion and after heat aging.
The iodine value determined according to the method is 120 or less, preferably 0-
The range is 100. The content of unsaturated nitrile units in the polymer rubber is determined by the unit content of the adherend rubber (highly saturated polymer rubber containing tolyl groups) during vulcanization bonding, or the unit content in other uses of the polymer rubber latex. Although it can be selected arbitrarily depending on the required performance, it is usually in the range of 910 to 60% by weight of the polymer rubber.

A method for producing the highly saturated nitrile group-containing composite rubber latex of the present invention by a phase inversion method will be described below.

The phase inversion method is a method in which a solution of a highly saturated polymer rubber containing nitrile groups and an aqueous emulsifier solution are mixed, the polymer rubber is emulsified and dispersed as fine particles in water by strong stirring, and the solvent is further removed. A latex of a highly saturated composite rubber containing nitrile groups is obtained. As the nitrile group-containing highly saturated polymer rubber solution at this time, the solution at the end of the polymerization and hydrogenation reactions can be used as it is, or it can be concentrated or diluted, or the rubber in a solid state can be used in a solvent. It can also be used after being dissolved.

Examples of the solvent include aromatic solvents such as benzene, toluene, and xylene, halogenated hydrocarbon solvents such as dichloroethane and chloroform, and ketones such as methyl ethyl ketone, acetone, and tetrahydrofuran, which are soluble in the polymer rubber, singly or in combination. used. The concentration of the highly saturated nitrile group-containing composite rubber in the solution is usually 1 to 25
% by weight. As the emulsifier, fatty acids such as oleic acid and stearic acid, potassium salts and sodium salts such as rosin acid, alkylbenzene sulfonic acid, and alkyl sulfuric acid ester, polyoxyethylene-based nonionic emulsifiers, etc. are used as emulsifiers. It can be used alone or in combination.

The volume ratio of the highly saturated nitrile group-containing polymer rubber solution to water is usually in the range of 3:1 to 1:20.

As a stirrer for emulsification and dispersion, various homo mixers, ultrasonic emulsifiers, etc. are used. Removal of the solvent from the emulsion is performed by a known method such as a steam stripping method.

The adhesive for vulcanizing and bonding the nitrile group-containing highly saturated composite rubber and polyester fibers of the present invention is a mixture of the above-mentioned nitrile group-containing highly saturated composite rubber latex with a resorcinol-formaldehyde resin. The resin used is conventionally used (for example, Japanese Patent Application Laid-Open No. 55-142635).
(e.g., those disclosed in the No. 1) can be used without any particular restrictions. In addition, 2,6-
It may also be used in combination with a compound such as a bis(2,4-dihydroxyphenylmethyl)-4-chlorophenol composition.

The adhesive of the present invention is usually a mixture of 10 to 180 parts by weight (dry weight) of a resorcinol-formaldehyde resin based on 100 parts by weight of the solid content of the polymer rubber latex of the present invention.

In addition, a part of the rubber latex of the present invention in the adhesive of the present invention may be a styrene-butadiene copolymer rubber latex or a modified latex thereof, to the extent that the gist of the present invention is not impaired.
It can be replaced with one or more of acrylonitrile-butadiene copolymer rubber latex, modified latex thereof, natural rubber latex, and the like.

The polyester fibers used in the present invention are not particularly limited, and can be any polyester fibers conventionally used as reinforcing fibers. Polyester fibers are used in the form of staples, filaments, cords, ropes, canvas, and the like.

The nitrile group-containing highly saturated composite rubber that is the adherend of the polyester fiber used in the present invention has the same monomer units as the nitrile group-containing highly saturated composite rubber that constitutes the latex of the present invention. The content of unsaturated nitrile units is usually 10 to 60% by weight from the viewpoint of oil resistance of rubber products composited with fibers, and the iodine value is preferably 120 or less from the viewpoint of heat resistance. is in the range of 0 to 100, more preferably 0 to 80.

Adhesion between the rubber and the fibers using the adhesive of the present invention is prepared by adding compounding agents such as a vulcanizing agent and a filler to the fibers and the rubber that have been dipped and heat-treated with the adhesive of the present invention. This is accomplished by vulcanizing the composite with a rubber compound.

The fibers were heat-treated with a resorcinol-formaldehyde-latex adhesive solution and heated at 100 to 150°C.
．． After drying for 5 to 10 minutes, it is further heat-treated at 200 to 260°C for 0.5 to 5 minutes to effect a curing reaction.

Note that, usually, prior to immersion in the treatment liquid, the fibers can be previously immersed in an isocyanate solution, an epoxy solution, or a mixture thereof, and then subjected to a drying treatment.

(Effects of the Invention) The nitrile group-containing highly saturated polymer rubber latex of the present invention is mixed with resorcinol-formaldehyde resin to form an adhesive for vulcanization bonding between rubber and polyester fibers. When used for vulcanization adhesion between fibers and fibers, it provides superior initial adhesive strength compared to conventional adhesives, and extremely remarkable adhesive strength after heat aging compared to conventional adhesives. Since this improvement has been achieved, organic synthetic fibers can be used in the production of various belts such as toothed conduction belts and belts, and various hoses such as pressure hoses and Freon hoses using organic synthetic fibers as tensile members.

(Example) The present invention will be described below in more detail by citing the present invention. Note that parts and percentages in Examples, Comparative Examples, and Reference Side are based on weight unless otherwise specified.

[Sample Preparation Example 1] (Preparation of highly saturated polymer rubber containing nitrile groups) (1) Monobutyl baroxypiparate 0.3 as a polymerization initiator
(2) potassium oleate 4phI11 as an emulsifier, ammonium persulfate 0.25 phm as a polymerization initiator, and coagulation. Rubber purified by repeating emulsion polymerization NBR prepared using calcium chloride aqueous solution as an agent and dissolving it three times and repeating reprecipitation, (3) the unpurified emulsion polymerization NnR and (4) polyoxynonylphenyl ether 5 phm as an emulsifier. , four types of NBR obtained by emulsion polymerization using 0.25 ptuw of ammonium persulfate as a polymerization initiator and temperature-sensitive coagulation at 110'C.
are dissolved in methyl ethyl ketone and hydrogenated using a Pd-carbon catalyst to produce a hydrogenated acrylonitrile-butadiene copolymer having an iodine value, a metal content other than alkali metals, and an ion content other than metal ions as shown in Table 1. Created rubber.

The metal content was measured using an atomic absorption spectrometer (model 28 manufactured by Hitachi, Ltd.).
0-50), and the contained metals include Pd and Mg+ Ca+ A I HSn, Cu, Zn+
Fe.

Assuming Si, the content of each of these metals was measured and expressed as the total value of each measured value. The ion content was measured using ion chromatography (Model 2000i manufactured by Dionex).
use. Columns are IIPIC-AS 1-5 and 11P
Use Ic-CS 1-2. ), and as ions other than the metal ions contained, Cl2-, so4g
Assuming -NO+-, PO43-, CO3''-, and Nfla', the content of each of these ions was measured and expressed as the sum of each measured value. It is listed in the table.

Example 1 540g of 60g of NBR or hydrogenated NBR shown in Table 1
was dissolved in a mixed solvent of methyl ethyl ketone/cyclohexane (50% by volume).

While stirring with a homomixer (M type manufactured by Tokushu Kika Kogyo),
32g of a 15% by weight potassium oleate aqueous solution adjusted to pH 11.5 with potassium hydroxide and 600g of water were mixed into NBR.
Or add it to a solution of hydrogenated NBR and turn it at 12,000 rpm/
Stir for 10 minutes to emulsify.

The solvent was removed from the resulting emulsion by steam stripping, and the emulsion was then concentrated using an evaporator to obtain a latex with a solid content of about 30% by weight. Further, the mixture was centrifuged at room temperature for 10 minutes at 10,000 rpm (Japanese centrifuge type H251) to obtain a concentrated latex.

Table 2 shows the solid content of the obtained latex, the content of metals other than alkali metals in the solid content, and the content of ions other than metal ions.

The metal content was determined using the same method as sample preparation example 1.
Expressed as the total value of each metal other than alkali metals. The same applies to the ion content.

[Example 2 of trial preparation] (Preparation of adhered rubber compound) According to the compounding recipe shown in Table 3, the nitrile group-containing highly saturated composite rubber and the compounding agent were kneaded on a roll, A sheet of rubber compound with a thickness of .

Table 3 Note) (1) Nippon Zeon products: Iodine value 28. Bound acrylonitrile M36% (City 2) Nippon Zeon product: Iodine value 4. Amount of bound acrylonitrile: 36% (Book 3) NOF product: α,α′-bis-L-butyl peroxide of m,p-diisopropylbenzene
0% Content Example 2 An adhesive (RFL liquid) was prepared using the latex listed in Table 2 according to the procedures in Tables 4 and 5.

Note) h) Valkabond E:2, manufactured by ICI Japan Co., Ltd.
6-bis(2,4-dihydroxyphenylmethyl)-4
-Chlorophenol composition Table 5 (Second bath RFL liquid) A polyester fiber cord (polyethylene terephthalate, structure 1500 d/2) was immersed in the first bath RFL liquid shown in Table 4 and heat treated at 235°C for 2 minutes. did. Then the fifth
It was immersed in the second bath RFL liquid shown in the table and heat-treated at 235°C for 2 minutes. This treated cord was sandwiched between sheets of rubber compound (a) or (b) of sample preparation example 2, and a cord pulling test (
H test: Samples were prepared according to 8 STM D 2138-72). The test piece was heated at 150°C for 30 minutes in the case of the rubber compound (a), and 16 minutes in the case of the rubber compound (b).
Vulcanization was performed at 0°C for 30 minutes. In order to examine the cord pull-out strength after aging, the test pieces were subjected to an air heat aging test at 120°C for 2 weeks. Table 5 shows the results of initial adhesive strength and adhesive strength after heat aging.

Reference example Nylon fiber cord (nylon 6, structure 1890 d/
2) was immersed in the RFL liquid shown in Table 6 and heat-treated at 200"C for 2 minutes. This treated cord was sandwiched between sheets of rubber compound (a) or (b) of sample preparation example 3, and A sample for a cord pullout test was prepared in the same manner as in 1.The results of the pullout test are shown in Table 7.

Table 6

Claims (1)

[Scope of Claims] 1. A latex of highly saturated composite rubber containing nitrile groups with an iodine value of 120 or less, in which the content of metals other than alkali metals in the solid content of the latex is 200 ppm or less, and A nitrile group-containing highly saturated polymer rubber latex, characterized in that the content of ions other than metal ions as measured by graphography is 100 ppm or less. 2. An adhesive comprising the nitrile group-containing highly saturated polymer rubber latex according to claim 1 and a resorcinol-formaldehyde resin for vulcanization bonding of a nitrile group-containing highly saturated polymer rubber and polyester fibers.