JP3173527B2 - Method for bonding aromatic polyamide fiber to hydrogenated nitrile rubber compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bonding a hydrogenated nitrile rubber compound to an aromatic polyamide fiber using an organic peroxide as a vulcanizing agent.

[0002]

2. Description of the Related Art Conventionally, a power transmission belt has been used as a power transmission means. Demands on heat resistance are becoming more stringent.

[0003] Usually, the power transmission belt is made of a composite of a fiber core and a rubber compound, and the fiber and the rubber compound are adhered by an adhesive. Therefore, as the demands for high load transmission resistance and heat resistance become severe, there is a strong demand not only for simply increasing the adhesive strength between the fiber and the rubber compound, but also for improving the adhesive strength particularly at high temperatures. Therefore, there is a need for a rubber compound having excellent heat resistance for the rubber compound itself to be bonded. Examples of rubber products having excellent heat resistance and oil resistance include hydrogenated nitrile rubber (hereinafter referred to as “H-NBR”).
Products) are known. H-NBR products maintain oil resistance, which is an advantage of conventional nitrile rubber products,
A rubber product with improved heat resistance. To prevent aging of rubber elasticity due to the recombination reaction of sulfur during thermal aging, hydrogen is added in advance to the double bond of the conventional nitrile rubber, and hydrogen is added during thermal aging. A bonding reaction is less likely to occur and heat resistance is improved. Therefore, in order to maintain the heat resistance of this H-NBR product, it is optimal to use a peroxide cross-linking system.

Further, in recent years, a rubber obtained by crosslinking a mixture of H-NBR and zinc methacrylate (MAZn) (hereinafter also referred to as "ZSC") with an organic peroxide imparts more heat resistance and strength to the product. And is applied to transmission belts, conveyor belts, and the like. Since many of these rubber products are composites with fiber materials as described above, the large adhesive force between the rubber products and the fiber materials is important in terms of the durability of the products and the manifestation of the properties of the composites. Has been requested.

Conventionally, as a method for bonding a rubber composition and a fiber material, a fiber material is treated in advance with a mixture of resorcinol, formalin, and rubber latex (hereinafter also referred to as “RFL liquid”). Methods for tightly vulcanizing a vulcanized rubber compound are well known. This method is effective for bonding with a sulfur vulcanized rubber compound. However, when the H-NBR and the aromatic polyamide fiber are bonded to each other, simply treating the aromatic polyamide fiber with the RFL liquid deteriorates the film formed by the RFL liquid because the H-NBR is a peroxide cross-linking system. The adhesive strength cannot be obtained.

There is also a method in which a fiber material is first treated with a liquid containing an isocyanate compound or an epoxy resin, then treated with an RFL liquid, and the outermost layer is treated with an epoxy resin or a mixed liquid of an epoxy resin and H-NBR. Are known.
However, in this method, since the epoxy resin is used, there is a problem that the strength and the elastic modulus of the epoxy layer are reduced particularly at a high temperature, and the adhesive strength is reduced.

Further, a method of treating a fiber material with a silane coupling agent is also known. However, since this method cannot form a sufficient adhesive layer thickness, the fiber is greatly deteriorated when vulcanized with an organic peroxide, and the tendency is particularly large in the case of a fiber having an amide bond, and strong adhesion is secured. Can not do it. The present invention has been made in view of such problems of the related art, and has as its object the purpose of having an adhesive layer having a certain thickness, and forming the outermost adhesive layer with hydrogenated nitrile rubber. Provide a layer with good adhesion,
An object of the present invention is to provide a method for bonding an aromatic polyamide fiber and a hydrogenated nitrile rubber compound, which can maintain good adhesive strength without causing a decrease in strength even at a high temperature.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems by bonding a hydrogenated nitrile rubber compound containing a metal salt of an unsaturated carboxylic acid to an aromatic polyamide fiber which is a core wire thereof. (1) a step of immersing the aromatic polyamide fiber in a liquid mixture containing an isocyanate compound or an epoxy resin; and (2) a step of immersing the fiber in a liquid mixture containing resorcinol, formalin, and rubber latex. (3) a step of immersing the fiber in a mixed solution containing an epoxy resin, a phenol resin and a hydrogenated nitrile rubber; and (4) an aromatic polyamide fiber immersed in each of the above steps. Is embedded in an unvulcanized hydrogenated nitrile rubber compound containing an organic peroxide as a vulcanizing agent and a metal salt of an unsaturated carboxylic acid. A method of bonding aromatic polyamide fibers and hydrogenated nitrile rubber composition which is characterized in that a step of vulcanizing the rubber compound.

The unsaturated carboxylic acid metal salt may be one or two.
An unsaturated carboxylic acid having two or more carboxyl groups is ionically bonded to a metal. As the unsaturated carboxylic acid, monocarboxylic acids such as acrylic acid and methacrylic acid, and dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid are preferable. In addition, Be, Mg, C
a, Sr, Ba, Ti, Cr, Mo, Mn, Fe, C
o, Ni, Cu, Ag, Zn, Cd, Hg, Al, S
n, Pb, or Sb can be used.

Among these, preferred metals are Mg, Ca,
Zn and Al. Particularly preferred unsaturated carboxylic acid metal salts are those represented by the following formula.

[0011]

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However, R and R 'each represent an aliphatic or aromatic hydrocarbon group or a hydrogen atom, and they may be the same or different. Me is any of the above metals, and n is an integer from 2 to 4. The content of the unsaturated carboxylic acid metal salt is preferably 15 to 80 parts by weight based on 100 parts by weight of the rubber component. Since the unsaturated carboxylic acid metal salt has high monomer reactivity, radicals generated from the organic peroxide are mostly consumed for the polymerization of the unsaturated carboxylic acid, and a part of the radical is generated between the rubber component and the adhesive component. Consumed for crosslinking. Therefore, it is possible to minimize the decrease in the adhesive strength due to the organic peroxide. This effect is small when the amount of the unsaturated metal carboxylate is less than 15 parts by weight per 100 parts by weight of the rubber component.
If the amount is more than 10 parts by weight, it is difficult to crosslink with the adhesive component, and it is difficult to adhere. From this point, the preferable amount of the unsaturated carboxylic acid per 15 parts by weight of the rubber component is 15 to 80.
Parts by weight, and most preferably 20 to 50 parts by weight.

Examples of the organic peroxide as the vulcanizing agent include benzoyl peroxide, lauroyl peroxide, ditertiary butyl peroxide, acetyl peroxide, tertiary butyl peroxybenzoic acid, dicumyl peroxide, peroxybenzoic acid. Preferred are acids, peroxides such as peroxyacetic acid and tert-butyl peroxypiparate, and diazo compounds such as azobisisobutyronitrile.

The nitrile group-containing highly saturated polymer rubber refers to an ethylenically unsaturated nitrile-conjugated diene-based highly saturated copolymer rubber, and the ethylenically unsaturated nitrile refers to one end of an ethylenically unsaturated bond. A compound to which a nitrile group (-CN) is added, such as acrylonitrile and methacrylonitrile. A conjugated diene is a compound in which two double bonds are bonded by a single bond, and examples thereof include butadiene and isoprene. A preferred combination is acrylonitrile-butadiene. The ethylenically unsaturated nitrile-conjugated diene rubber is preferably subjected to hydrogenation in order to increase the degree of saturation. Hydrogenation saturates 10 to 100% of the unsaturated bonds in the rubber. Since the nitrile group-containing highly saturated polymer rubber is contained in the adhesive component, the crosslinking efficiency of the organic peroxide is reduced, and the influence of the organic peroxide on the adhesive layer can be reduced.

The phenolic resin preferably reacts with the epoxy resin, and can be used in either a novolak type or a resole type. By mixing with a nitrile group-containing highly saturated polymer rubber, the cohesive force of the adhesive can be increased. , RF
Enhances the effect of bonding with L liquid.

The RFL solution is obtained by mixing an initial condensate of resorcinol and formalin with a rubber latex. Generally, the molar ratio of resorcinol to formalin is 1: 0.5 to
3 is preferred. As the rubber latex, a synthetic rubber latex can be used, and acrylonitrile-rubber latex is preferable.

[0017]

The adhesion can be enhanced by treating the aromatic polyamide fiber with an isocyanate compound or an epoxy resin before treating it with the RFL solution. Also, this R
Since the phenol resin is contained in the outermost adhesive layer in contact with the FL liquid treatment layer, it has a good affinity with the RFL liquid, and the outermost adhesive layer contains hydrogenated nitrile rubber. Therefore, it has good compatibility with epoxy resin and phenol resin, and this hydrogenated nitrile rubber cooperates with the unsaturated carboxylic acid metal salt in the rubber to be bonded to suppress the decrease in adhesive force due to organic peroxide, However, a strong adhesion between the aromatic polyamide fiber and the hydrogenated nitrile rubber compound can be maintained. Furthermore, the phenolic resin contained in the outermost adhesive layer reacts with the epoxy resin, and it is possible to prevent the adhesive strength of the epoxy resin from decreasing at high temperatures.

[0018]

Embodiments of the present invention will be described below. (Example 1) A cord of an aromatic polyamide fiber having a configuration of 1500d / 2x3 (trade name "Kevlar" manufactured by DuPont) was immersed in a treatment liquid having a composition (parts by weight) shown in Table 1 (a) below. After 47
Heat treatment was performed at 3K for 2 minutes, and then immersion in an RFL solution having the composition (parts by weight) shown in Table 2 and heat treatment at 473K for 2 minutes. Then, a composition shown in Table 3 in which H-NBR, an epoxy resin and a novolak phenol resin were mixed at a ratio of 2: 2: 1 was dissolved in methyl ethyl ketone to obtain a mixed solution. The cord was dipped and dried at 373K. Next, this bonded fiber cord was embedded in a ZSC composition having the composition (parts by weight) shown in Table 4 and 443
Vulcanized at K for 30 minutes. The rubber product thus obtained was allowed to cool at room temperature for 24 hours, left at 393K for 30 minutes, and then measured for peel adhesion at the same temperature under the conditions of a pulling speed of 50 mm / min. Use "Autograph"). The bending stiffness of the bonded fiber cord was measured (a pure bending tester KES manufactured by Kato Tech Co., Ltd.).
use).

Example 2 The mixing ratio of H-NBR, epoxy resin and novolak phenol resin in Table 3 was 1:
A rubber product was obtained in the same manner as in Example 1 except that the ratio was 4: 2, and the peel adhesion of the rubber product and the bending rigidity of the bonded fiber cord were measured in the same manner.

(Example 3) A rubber product was obtained in the same manner as in Example 1 except that the liquid in which the aromatic polyamide fiber cord was immersed was changed to the composition (b) in Table 1, and the rubber product was obtained in the same manner. The peel adhesion and the bending rigidity of the bonded fiber cord were measured.

Example 4 A liquid in which an aromatic polyamide fiber cord was immersed was designated as composition (b) in Table 1, and H-N in Table 3 was used.
A rubber product was obtained in the same manner as in Example 1, except that the mixing ratio of BR, epoxy resin, and novolak-based phenol resin was 1: 4: 2. The bending stiffness of the fiber cord was measured.

(Comparative Examples 1 to 3) The liquid in which the aromatic polyamide fiber cord was immersed was the composition (b) in Table 1, and the liquid composition in which the fiber cord after the RFL treatment was immersed was as shown in Table 3. A rubber product was obtained in the same manner as in Example 1 except that the rubber product was peeled off, and the peel adhesion of the rubber product and the bending stiffness of the bonded fiber cord were measured in the same manner.

Table 3 shows the measurement results of the peeling adhesive strength and the bending stiffness of Examples 1 to 4 and Comparative Examples 1 to 3.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

As is evident from Table 3, it can be seen that all of the examples of the present invention show high adhesive strength at high temperatures, and have low flexural rigidity and excellent fatigue resistance. However, those according to Comparative Examples 1 and 2 have low adhesive strength, and furthermore,
The one according to Comparative Example 1 is inferior in fatigue resistance because of high bending rigidity. Further, the one according to Comparative Example 3 has a high adhesive strength, but has a high bending rigidity, and thus is inferior in fatigue resistance.

[0029]

The aromatic polyamide fiber and the hydrogenated nitrile rubber bonded by the bonding method according to the present invention have high adhesive strength at high temperature and excellent fatigue resistance. Belts, conveyor belts, rubber hoses, tires, etc., whose main material is a rubber composition to be used.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI D06M 15/693 D06M 15/693 // D06M 17/04 D06M 17/04 D06M 101: 36 (58) Fields surveyed (Int.Cl. . ^7, DB name) C08J 5/12 CFG C08J 5/12 CEQ C08C 19/34 D06M 15/41 D06M 15/55 D06M 15/693 D06M 17/04

Claims (1)

(57) [Claims] 1. Hydrogen containing a metal salt of an unsaturated carboxylic acid
Nitrile rubber compound and its core, aromatic polya
A method for adhering to a mid fiber , wherein a mixed solution containing an isocyanate compound or an epoxy resin is used.
A step of immersing the aromatic polyamide fiber, the fiber and resorcin and formalin and rubber latex
Immersion treatment in a mixed solution containing the resin, the fiber being an epoxy resin, a phenol resin and a hydrogenated nitrite.
A step of immersing in a mixed solution containing ril rubber, and an aromatic polyamide fiber immersed in each of the above steps
With a vulcanizing agent, an organic peroxide and an unsaturated metal carboxylate
Embedded in unvulcanized hydrogenated nitrile rubber compound containing salt
And vulcanize this unvulcanized hydrogenated nitrile rubber compound
Method of bonding aromatic polyamide fibers and hydrogenated nitrile rubber compound is characterized by having a step.