JPH0218427A - Method for bonding hydrogenated nitrile rubber blend to fiber - Google Patents

Abstract

PURPOSE:To carry out bonding with excellent flex fatigue resistance, etc., by fixing a mixture solution of a rubber latex, etc., on a fiber subjected to activa tion treatment, treating the fiber with an adhesive composition containing an isocyanate, then closely adhering the fiber to rubber and vulcanizing the resul tant blend. CONSTITUTION:(A) A fiber, such as glass fiber or cotton, is treated with (B) any active compound of a polyisocyanate, polyepoxy compound and silane coupling agent, then dipped in (C) a resorcin.formalin.rubber latex mixture solution and heat-treated. The resultant fiber is subseuquently treated with (D) an adhesive composition consisting of (i) 1-90wt.% polymer, such as chloro prene rubber, with 25-70wt.% halogen content and (ii) 10-99wt.% polyisocyanate compound, such as tolylene diisocyanate, or blocked polyisocyanate, and then closely adhered to (E) the subject unvulcanized rubber blend and vulcanized to carry out the objective bonding.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adhering a hydrogenated nitrile rubber compound to fibers.

Hydrogenated nitrile rubber is known as a rubber that has both oil resistance and heat resistance. This hydrogenated nitrile rubber has improved heat resistance while retaining the oil resistance that is an advantage of conventional nitrile rubber. By hydrogenating the double bonds contained in nitrile rubber, it is resistant to heat aging. The sulfur recombination reaction is difficult to occur, thus preventing a decrease in rubber elasticity due to the sulfur recombination reaction.

Conventionally, RFL is generally used as a bonding method for rubber and fibers.
A well-known method is to treat fibers in advance with a mixture of resorcin/formalin and rubber latex, which is called liquid, and then vulcanize this in close contact with unvulcanized rubber. Regarding adhesion between hydrogenated nitrile rubber and fibers, for example, JP-A-58
Publication No. 45940 describes acrylonitrile-butadiene rubber latex containing carboxyl groups and resorcinol-containing rubber latex.
A method has been proposed in which fibers are treated with a mixture of formalin and vulcanized in close contact with hydrogenated nitrile rubber. A method has been proposed in which fibers are treated with a resorcinol-formalin mixture and the fibers are vulcanized in close contact with hydrogenated nitrile rubber.

Thus, by treating the fibers with resorcinol-formalin-rubber latex, it is possible to achieve a certain degree of adhesion between the fibers and the hydrogenated nitrile rubber; Sufficient adhesion to withstand applications with high shear between
cannot be achieved.

Another known method is to treat fibers with a polyisocyanate compound or a polyepoxy compound and vulcanize the fibers in close contact with unvulcanized rubber. For example, JP-A-62-133187 describes a method of treating carbon fibers with an adhesive composition consisting of chlorosulfonated polyethylene rubber and a polyisocyanate compound and vulcanizing and adhering them to hydrogenated nitrile rubber. ing.

However, when using this method, for example, when bonding a fiber cord to hydrogenated nitrile rubber, an adhesive composition containing polyisocyanate or an epoxy compound penetrates into the fiber cord, hardens the fiber cord, and prevents its bending. Significantly impairs sexuality.

The present invention was made in order to solve the above-mentioned problems in adhesion between hydrogenated nitrile rubber compounds and fibers. Achieves strong adhesion that can withstand various applications, and in the case of fiber cords, has a high strength retention rate (and
The object of the present invention is to provide a method for adhering fibers to a hydrogenated nitrile rubber compound that provides adhesion with excellent bending fatigue resistance.

The method of adhering a hydrogenated nitrile rubber compound and fibers according to the present invention to eliminate interstitial bonding includes a first step of treating the fibers with an active compound selected from polyisocyanates, polyepoxy compounds, and silane coupling agents. , a second step of immersing in a resorcinol/formalin/rubber latex mixture and heat treatment; 1 to 90% by weight of a polymer with a halogen content of 25 to 70% by weight and 10 to 99% by weight of a polyisocyanate compound or blocked polyisocyanate; and a fourth step of contact vulcanization with an unvulcanized hydrogenated nitrile rubber compound.

In the method of the present invention, the active compounds used in the first step are selected from polyisocyanates, polyepoxy compounds and silane coupling agents, and by treating the fibers with such compounds, the fibers are freed of chemically active functional groups. granted and activated.

The polyisocyanate compound is not particularly limited, but for example, polyisocyanates such as tolylene diisocyanate, metaphenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and polymethylene polyphenyl diisocyanate are preferably used. Further, polyhydric alcohol-added polyisocyanates obtained by reacting such polyisocyanates with compounds having two or more active hydrogens in the molecule, such as trimethylolpropane and pentaerythritol, and polyisocyanates with phenols added to the polyisocyanates, Blocked polyisocyanates, in which isocyanate groups of polyisocyanates are blocked by reacting blocking agents such as primary alcohols and secondary amines, are also suitably used as polyisocyanate compounds.

Examples of polyepoxy compounds include polyhydric alcohols such as ethylene glycol, chrycerin, sorbitol, and pentaerythritol, reaction products of polyalkylene glycols such as polyethylene glycol, and halogen-containing epoxy compounds such as shrimp chlorohydrin, resorcinol,
Polyhydric phenols such as bis(4-hydroxyphenyl) dimethylethane, phenol-formamide resin, and resorcinol-formamide resin, and reaction products of phenol resins and halogen-containing epoxy compounds such as epichlorohydrin are preferably used.

In addition, examples of the silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-metacycloxypropyltrimethoxysilane, γ-metacycloxypropyl Examples include tris(β-methoxy)silane and vinyltriacetoxysilane.

In the first step, the fibers are treated with the active compound by making the active compound into a solution, immersing the fibers in the solution, and then subjecting the fibers to a heat treatment, if necessary. This heat treatment may be carried out at a temperature sufficient to react and fix the active compound attached to the fiber, although it depends on the type of fiber used, and is usually carried out at 100-250° C. for several minutes.

As mentioned above, the treatment of the fibers with the active compound in the first step imparts functional groups to the fibers, so in the second step described below, the fibers are treated with a mixture of resorcin formalin and rubber latex (hereinafter referred to as When treated with a resorcinol-formalin-rubber latex mixture (resorcinol-formalin-rubber latex mixture), it firmly adheres to the fibers, and in turn forms a strong bond between the fibers and the hydrogenated nitrile rubber.

In the method of the present invention, in the second step, the fibers are then immersed in a resorcinol/formalin/rubber latex mixture and heat treated.

The resorcin/formalin used in the resorcin/formalin/rubber latex mixture preferably has a resorcin/formalin molar ratio in the range of 1/3 to 3/1, and the rubber latex solid content/resorcin/formalin solid content weight ratio is It is preferably in the range of 10/1 to 1/3. In addition, the above rubber latex includes acrylonitrile-butadiene copolymer rubber (NBR) latex, carboxylated acrylonitrile-butadiene copolymer rubber (NBR) latex, styrene-butadiene copolymer rubber (SBR) latex, and vinylpyridine. (V
p) Rubber latex, chloroprene rubber (CR) latex, chlorosulfonated polyethylene rubber latex, etc. are preferably used.

After being immersed in the resorcinol/formalin/rubber latex mixture, the fibers are typically heated to a temperature in the range of 100 to 250° C. for several minutes to fix the resorcinol/formalin/rubber latex mixture to the fibers.

The treatment of fibers with the resorcinol/formalin/rubber latex mixture increases the wettability of the adhesive composition to the fibers, which will be described next, and also increases the wettability of the adhesive composition inside the fiber cord when adhering the fiber cord and rubber. This prevents penetration into the adhesive and thus allows effective adhesion to be obtained with small amounts of adhesive composition. Preventing the adhesive composition from penetrating into the fiber cord prevents the cord from becoming hard, thereby increasing the bending fatigue resistance of the cord.

Next, in the method of the present invention, as described above, after the fibers are treated with resorcinol/formalin/rubber latex, a halogen-containing M25 to 70% by weight is added as the third step.
and 10 to 99% by weight of a polyisocyanate compound or blocked polyisocyanate.

As the halogen-containing polymer in the adhesive composition, chlorinated rubber, polyvinyl chloride, chloroprene rubber, chlorosulfonated polyethylene rubber, etc. are preferably used.

The halogen-containing polymer used in the present invention must have a halogen content in the range of 25 to 70% by weight, and if the halogen content is outside this range, the hydrogenated nitrile rubber and fibers may The adhesive strength between them is extremely weak.

The polyisocyanate in the adhesive composition is also not particularly limited, but for example, polyisocyanates such as tolylene diisocyanate, metaphenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and polymethylene polyphenyl diisocyanate are preferably used. In addition, polyhydric alcohol-added polyisocyanates obtained by reacting such polyisocyanates with compounds having two or more active hydrogens in the molecule, such as trimethylolpropane and pentaerythritol, and polyisocyanates with phenols and tertiary Blocked polyisocyanates, in which isocyanate groups of polyisocyanates are blocked by reacting blocking agents such as alcohols and secondary amines, are also suitably used as polyisocyanate compounds.

The treatment of fibers with the adhesive composition described above can also be carried out by dissolving the z-logen-containing polymer and the polyisocyanate compound in an appropriate organic solvent to form an adhesive composition in the form of a solution, and then immersing the fibers in the adhesive composition. After that, heat treatment is performed as necessary. The organic solvent is not particularly limited, but aromatic hydrocarbons such as benzene, toluene, and xylene, ethers, and halogenated aliphatic hydrocarbons such as trichloroethylene are usually preferably used. As mentioned above, the above heat treatment also depends on the type of fiber used, but it may be carried out at a temperature sufficient to react and fix the above compound attached to the fiber, and usually at a temperature of 250°C or less for several minutes. Just heat it.

In this third step of fiber treatment, the halogen-containing polymer has a highly polar halogen group in its molecule, so it has high compatibility with the rubber latex and is itself strongly adsorbed to the fiber. It not only has high compatibility with hydrogenated nitrile rubber, but also has high compatibility with rubber latex and hydrogenated nitrile rubber. are co-crosslinked, thus achieving strong adhesion between the fibers and the hydrogenated nitrile rubber.

The adhesive composition may contain, if necessary, various additives that are usually added to hydrogenated nitrile rubber, such as carbon black, fillers, softeners, anti-aging agents, zinc white, and the like.

In addition, the hydrogenated nitrile rubber compound may also contain appropriate amounts of various reinforcing fillers, anti-aging agents, plasticizers, vulcanization aids, processing aids, etc., which are known as ordinary rubber compounds. good. Further, it is also possible to apply a hydrogenated nitrile rubber compound as a paste rubber to the fibers subjected to the above-mentioned treatment and vulcanize the mixture in close contact with the hydrogenated nitrile rubber compound. .

The hydrogenated nitrile rubber used in the method of the present invention preferably has a hydrogenation rate in the range of 80 to 99%.

In the method of the present invention, typical fibers include cotton, human silk, polyvinyl alcohol fiber, aliphatic polyamide fiber, aromatic polyamide fiber, polyester fiber, glass fiber, carbon fiber, etc. The fibers are not particularly limited, and include all fibers conventionally used for bonding with rubber.

The fibers treated as described above are then brought into intimate contact with a hydrogenated nitrile rubber compound and vulcanized and bonded under conventional processing conditions known for hydrogenated nitrile rubber compounds.

As described above, according to the method of the present invention, in the first step, fibers are treated with an active compound to activate them, and a mixture of resorcinol, formalin, and rubber latex is adhered and bonded to the fibers. Furthermore, since the fibers are treated with an adhesive composition that is highly compatible with hydrogenated nitrile rubber, extremely strong adhesion can be achieved between the hydrogenated nitrile rubber and the fibers. Further, according to the method of the present invention, when adhering the fiber cord and hydrogenated nitrile rubber, the adhesive composition does not penetrate into the inside of the fiber cord, so the strength retention rate is high.
Adhesion with excellent fatigue resistance can be obtained.

Therefore, the method of the present invention is suitable for bonding fibers as reinforcing bodies of hydrogenated nitrile rubber in dynamic products such as power transmission belts, conveyor belts, tires, etc., for example.

The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 Aromatic polyamide fiber cord (Kevlar manufactured by DuPont,
1500D/2x3) in an aqueous solution containing 5% by weight of a water-soluble epoxy resin (Denacol EX313, glycerol polyglycidyl ether manufactured by Nagase Sangyo ■) (hereinafter sometimes referred to as treatment solution A), and then heated to 200°C. The sample was heat-treated for 2 minutes.

Next, this fiber cord was treated with 5.0 parts by weight of resorcin, 3
Resorcinol formalin rubber latex with a resorcinol/formalin molar ratio of 1.2/1, consisting of 3.1 parts by weight of 7% formalin, 61.6 parts by weight of NBR latex (N1pol 1562 manufactured by Nippon Zeon ■) and 84.3 parts by weight of water. After being immersed in a mixed solution (hereinafter sometimes referred to as treatment solution H), it was heated and dried at 200° C. for 2 minutes.

After that, the fiber cord treated in this way was immersed in each of the adhesive compositions W, X and Y shown in Table 1.
) It was heated and dried at 0°C for 2 minutes.

Here, the adhesive compositions W, X, and Y contain a halogen-containing polymer (inventions 1 to 3).

As a comparative example, fibers were treated in the same manner as above except that adhesive composition Z containing a halogen-free polymer as a component was used instead of the halogen-containing polymer (Comparative Example 1).

Furthermore, as a comparative example, the same fiber cord as above was treated with treatment liquid A.
After treatment with adhesive compositions w, x, y, and Z without treatment with the resorcinol/formalin/rubber latex mixture (Comparative Examples 2 to 6).

Each of the fiber cords treated as described above was coated with hydrogenated nitrile rubber (Zetpol 2020 manufactured by Nippon Zeon),
Hydrogenation rate 90%) 100 parts by weight, Zinc White No. 1 5 parts by weight, stearic acid 1 part by weight, sulfur 0.5 parts by weight, SFR
Cords were placed on a sheet made of an unvulcanized hydrogenated nitrile rubber compound consisting of 40 parts by weight of carbon, 2 parts by weight of tetramethylthiuram disulfide, and 0.5 parts by weight of mercaptobenzothiazole so that the cord spacing was approximately 31)1. They were lined up and vulcanized and bonded at 160°C for 20 minutes.

After vulcanization and adhesion, the sample was cut into 1-inch width pieces, and the peel adhesion strength was measured using a peel tester at a peel angle of 90° and a tensile speed of 50 mm/min. The results are shown in Table 2.

Further, FIG. 1 shows the relationship between the chlorine content of each chlorine-containing polymer in the adhesive composition shown in Table 1 and the above-mentioned peel adhesive strength.

EXAMPLE 2 Thickness 1.1 of the same hydrogenated nitrile rubber formulation as above.
A sheet of 0 Tsuru was wound on a drum, each of the fiber cords treated in Example 1 was spun thereon, and the same hydrogenated nitrile rubber compound sheet as above was laminated thereon. co! A sample was prepared in which two of the above fiber cords were embedded in a vulcanized adhesive by steam vulcanization for 35 minutes under a pressure of .

This sample was wrapped around a rotating bending bar positioned vertically, one end of the process was fixed to the frame, and a 1.5 kg weight was attached to the other end.
A bending test was conducted by applying a load of 100,000 times and reciprocating the rotary bending bar 100,000 times.

The obtained strength retention rates are shown in Table 2. Here, the strength retention rate is the value obtained by dividing the strength before bending by the strength after testing.

Example 3 In the method of the present invention of Example 1 (Table 2 Invention 1),
Fiber cords were treated with various blending ratios of the halogen-containing polymer and polyisocyanate compound in the adhesive composition, and the same hydrogenated nitrile rubber unvulcanized rubber compound as described above was used as the adherend. Adhesion and bending tests were carried out in the same manner as in Examples 1 and 2. Second result
As shown in the figure.

Example 4 In the method of the present invention of Example 1 (Table 2 Invention 1),
The same fiber cord as above was treated in the same manner as in Examples 1 and 2, except that resorcinol/formalin/rubber latex mixed liquids 1J and K shown in Table 3 were used in place of treatment liquid A. It was adhered to a sheet made of the hydrogenated nitrile rubber compound. In the same manner as in Examples 1 and 2, the peel adhesion strength and labor-saving retention rate of these adhesives were measured. The results are shown in Table 4.

Table 3 (Note) ■) Manufactured by Nippon Zeon ■ 2) Manufactured by Nippon Synthetic Rubber ■ 3) Manufactured by Electrochemical ■ Example 5 Treatment liquid consisting of 5 parts by weight of 4.4-diphenylmethane diisocyanate phenol block and 95 parts by weight of water B
, and 5 parts by weight of α-aminopropyltriethoxysilane and 95 parts by weight of water.

In the method of the present invention of Example 1 (Table 2 Invention 1),
After treating the same fiber cord as above with each of the above treatment liquids B and C, it was vulcanized and bonded to a sheet made of the same hydrogenated nitrile rubber compound as above in the same manner as in Examples 1 and 2, and then peeled off. Adhesive strength and strength retention were measured. The results are shown in Table 2.

Example 6 In the method of the present invention of Example 1 (Table 2 Invention 1),
Except for using the fiber cords shown in Table 5, Table 5 (Note) ■) a indicates polyvinyl alcohol, b indicates fatty Ej group polyamide, and C indicates polyester.

In the same manner, it was vulcanized and adhered to a sheet made of the same hydrogenated nitrile rubber compound as above, and the peel adhesion and strength retention were measured. The results are shown in Table 5.

[Brief explanation of the drawings] Figure 1 shows the relationship between the chlorine content and adhesive strength of the chlorine-containing polymer used in the adhesive set used in bonding the hydrogenated nitrile rubber compound and the aromatic basket fiber cord. Graph showing the y coefficient (
Example 1) and Figure 2 show the relationship between the weight ratio of the chlorine-containing polymer/polyisocyanate and the adhesive force and C It is a graph (Example 1) showing a relationship. Patent Applicant Band-Kagaku Co., Ltd. Agent Patent Attorney Ittsu Makino Department Figure 1 Prefecture F ¥1 + (% dice)

Claims (1)

[Claims] (1) In the method of adhering a hydrogenated nitrile rubber compound to fibers, the first step is to treat the fibers with an active compound selected from polyisocyanates, polyepoxy compounds, and silane coupling agents, and a mixture of resorcinol, formalin, and rubber latex. A second step of immersion in a solution and heat treatment, with an adhesive composition consisting of 1 to 90% by weight of a polymer with a halogen content of 25 to 70% by weight and 10 to 99% by weight of a polyisocyanate compound or blocked polyisocyanate. A method for adhering a hydrogenated nitrile rubber compound to fibers, comprising a third step of treating the mixture, and a fourth step of closely vulcanizing the unvulcanized hydrogenated nitrile rubber compound.