JP3030466B2 - Method for bonding aromatic polyamide fiber to rubber compound - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for bonding an aromatic polyamide fiber to a rubber compound, and more particularly, to a fiber having particularly high bonding strength and excellent bending fatigue resistance. The present invention relates to a method for obtaining an adhesive composite of an aromatic polyamide fiber and a rubber compound.

2. Description of the Related Art Generally, industrial rubber products such as tires, rubber hoses, power transmission belts, and conveyor belts are reinforced with a fiber material. In particular, in recent years, aromatic polyamide fibers have been widely used as reinforcing materials. The aromatic polyamide fiber has a high melting point, a high strength, and a high modulus, and retains these excellent properties even under high temperature and high humidity, and has a small creep (permanent strain) against repeated stress stimulation.

Conventionally, to bond a fiber and a rubber compound, generally,
There is known a method of treating fibers with a resorcinol-formalin-rubber latex mixture (hereinafter, referred to as an RFL solution). According to this method, the adhesion obtained between the aromatic polyamide fibers and the rubber compound is very poor.

Therefore, conventionally, various methods have been proposed to solve such a problem. For example, a method of treating a fiber with an epoxy compound or a polyisocyanate compound is known. According to this method, the adhesive strength can be obtained to some extent, but the fiber is inferior in bending fatigue resistance. After the above treatment, a method of treating the fiber with an RFL solution is also known. According to this method, the bending fatigue resistance of the fiber is improved, but the obtained adhesive strength is insufficient.

JP-A-58-124631 proposes a method of treating fibers with a urethane-modified epoxy resin, and then treating the fibers with an RFL solution. We have not reached a satisfactory level. JP-A-63-
No. 66382 proposes a method in which a fiber is impregnated with a liquid rubber and then treated with an RFL solution in order to improve the bending fatigue resistance of the fiber. Is not enough.

Further, a method has been proposed in which fibers are pretreated with a solution containing an epoxy compound and a liquid rubber, and then treated with an RFL solution. However, this method also does not provide an adhesive that satisfies both the fiber adhesive strength and the bending fatigue resistance.

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional bonding of an aromatic polyamide fiber and a rubber compound, and has particularly high bonding strength and bending fatigue resistance. It is an object of the present invention to provide a production method capable of obtaining an adhesive composite of an aromatic polyamide fiber having the following and a rubber compound.

Means for Solving the Problems The present invention relates to a method for bonding an aromatic polyamide fiber and a rubber compound, wherein the aromatic polyamide fiber is added to (a) 100 parts by weight of an epoxy compound having at least one epoxy group in a molecule. A first step of treating with a solution containing 1 to 100 parts by weight of a liquid rubber and 5 to 20 parts by weight of a blocked polyisocyanate, (b) a second step of treating with a mixed solution of resorcinol, formalin and rubber latex, and (c) The method is characterized by including a third step of tightly vulcanizing the unvulcanized rubber compound.

In the method of the present invention, examples of the aromatic polyamide fiber include poly-p-benzamide, poly-m-benzamide, poly-p-phenylene terephthalamide, poly-m-phenylene isophthalamide, and 1,4-phenylene. Fibers composed of nylene terephthalamide-3 ', 4'-diaminodiphenyl ether copolymer and the like can be mentioned.

According to the method of the present invention, as the first step, 1 to 100 parts by weight of the liquid rubber and 100 parts by weight of the epoxy compound having at least one epoxy group in the molecule are mixed with the aromatic polyamide fiber and the blocked polyisocyanate 5 ~ 20
After being immersed in a solution containing parts by weight (hereinafter sometimes referred to as a treatment liquid), heat treatment is performed.

The epoxy compound used in the method of the present invention is a compound having at least one epoxy group in a molecule, for example, a polyhydric alcohol such as ethylene glycol, glycerin, sorbitol, and pentaerythritol;
Reaction products of a polyalkylene glycol such as polyethylene glycol and a halogen-containing epoxy compound such as epichlorohydrin, and polyhydric phenols such as resorcin, bis (4-hydroxyphenyl) dimethylethane, phenol-formamide resin, and resorcin-formamide resin And the reaction products of phenolic resins and halogen-containing epoxy compounds such as epichlorohydrin are preferably used. An epoxy compound obtained by oxidizing a double bond of an aliphatic or alicyclic unsaturated compound with acetic acid or the like is also preferably used. Various silane coupling agents having an epoxy group are also preferably used.

As the liquid rubber, for example, polybutadiene, polyisoprene, styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, and the like are used.In particular, in order to improve the adhesive strength and mechanical properties of the obtained adhesive composite, Liquid rubbers having an active functional group such as an amino group, a hydroxyl group or a carboxyl group at the molecular terminal are preferably used. In particular, a liquid chloroprene rubber having an active functional group such as an amino group, a hydroxyl group or a carboxyl group at the molecular terminal is preferably used because it gives an adhesive composite having excellent fiber adhesive strength and bending fatigue resistance.

In the method of the present invention, the solution used in the first step is
Liquid rubber 1 to 100 parts by weight of the epoxy compound 100 parts
It is necessary to include parts by weight. In the solution, when the liquid rubber is less than 1 part by weight with respect to 100 parts by weight of the epoxy compound, the fiber is hard and inferior in bending fatigue resistance in the obtained adhesive composite, and when it exceeds 100 parts by weight, For example, when fiber cord and rubber are bonded,
In the resulting adhesive composite, the fiber cord is flexible, but the amount of the epoxy compound is relatively too small, resulting in insufficient adhesive strength in the adhesive composite.

Further, the solution contains a blocked polyisocyanate. Free polyisocyanates cannot be used because their reactivity is much higher than the reactivity of epoxy compounds and liquid rubbers.

The polyisocyanate in the blocked polyisocyanate is not particularly limited. Used for

Such a blocked polyisocyanate of a polyisocyanate can be obtained, for example, by reacting a polyisocyanate with a compound having two or more active hydrogens in the molecule, such as trimethylolpropane or pentaerythritol. The blocked polyisocyanate can also be obtained, for example, by reacting a phenol or an amine with the polyisocyanate.

In the solution, the blocked polyisocyanate is contained in an amount of 5 to 20 parts by weight based on 100 parts by weight of the epoxy compound.

Solvents for forming the solution are not particularly limited, but are usually aromatic hydrocarbons such as benzene, xylene, and toluene, aliphatic ketones such as methyl ethyl ketone and methyl isobutyl ketone, ethyl acetate, and amyl acetate. And the like are preferably used. The solid content concentration in such a solution is not particularly limited,
Usually, a range of 5 to 50% by weight is suitable.

According to the method of the present invention, as a first step, the aromatic polyamide fiber is immersed in the solution as described above and heat-treated. This heat treatment may be performed at a temperature sufficient to cause the solution attached to the fibers to react and fix.
What is necessary is just to process at several degrees C for several minutes.

Next, according to the method of the present invention, the aromatic polyamide fiber is treated with an RFL solution. As described above, the RFL liquid is a resorcinol-formalin, rubber latex mixture,
Conventionally, it is generally known in the bonding between rubber and fiber, and usually, resorcinol and formalin are condensed in the presence of a basic catalyst at a resorcinol / formalin molar ratio of 1/3 to 3/1. This is an aqueous mixture obtained by mixing the precondensate obtained by the above with a rubber latex. When the resorcinol / formalin molar ratio is outside the above range, an initial condensate having a molecular weight necessary for adhesion cannot be obtained.

As the rubber latex, generally, a synthetic rubber latex is used. For example, chloroprene rubber latex, styrene-butadiene-vinylpyridine rubber latex, acrylonitrile-butadiene rubber latex,
Hydrogenated nitrile rubber latex is preferably used.

The treatment of the aromatic polyamide fiber with the RFL solution may be performed at a temperature sufficient to cause the latex adhered to the fiber to react and fix to the fiber, and may be generally treated at 100 to 270 ° C. for several minutes.

Further, according to the method of the present invention, prior to the first step,
Aromatic polyamide fibers can be treated with solutions of isocyanates, epoxy compounds or mixtures thereof. This treatment is also performed by immersing the aromatic polyamide fiber in the solution and, if necessary, heat-treating the compound to fix the compound to the fiber. To form a solution of the isocyanate compound or the epoxy compound as described above. As the organic solvent, those described above are usually used.

The aromatic polyamide fiber treated as described above is then brought into close contact with a rubber compound as a third step, and is vulcanized and bonded under ordinary processing conditions known for the rubber compound.

In the present invention, for example, styrene-butadiene rubber, ethylene-propylene rubber, butyl rubber, chloroprene rubber, acrylonitrile-butadiene rubber, hydrogenated nitrile rubber, and the like are used as the rubber. Such rubbers may, depending on each case, contain appropriate amounts of various reinforcing fillers, antioxidants, plasticizers, vulcanization aids, processing aids, etc. known as ordinary rubber compounds. .

EXAMPLES Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1 An aromatic polyamide fiber cord (1500D / 2 × 3 fiber cord made of Kevlar fiber manufactured by DuPont) was immersed in a treatment liquid C having the composition shown in Table 1, and then heat-treated at 235 ° C. for 1 minute. .

Next, after being immersed in the RFL solution D having the composition shown in Table 2, it was heat-treated at 200 ° C. for 1 minute.

Thereafter, the fiber cord was placed on a 4 mm thick sheet of chloroprene rubber compound F having the composition shown in Table 3 to obtain
After arranging in parallel at 3 mm intervals while applying a load of g / D,
Vulcanization was performed at 150 ° C. for 30 minutes to obtain an adhesive sample.

The following test was performed on this adhesive sample. The results are shown in Table 4.

Initial adhesive force A 180 ° peel force was measured when the fiber cord was peeled from the adhesive sample at 100 mm / min.

Retention rate of adhesive strength after fatigue Using a Scott bending tester, applying a tension of 0.6 g / D, 2 ×
After bending 10 ⁴ times, in the same manner as described above by measuring the 180 ° peel strength was determined the ratio of the processing adhesion.

Retention of fiber cord strength after fatigue The strength of the fiber cord after bending fatigue was measured in the same manner as above, and the ratio to the initial strength was determined.

Example 2 A sheet having a thickness of 4 mm comprising a treatment liquid C having a composition shown in Table 1, an RFL liquid E having a composition shown in Table 2, and a hydrogenated nitrile rubber compound G having a composition shown in Table 3 was prepared. Except for using, an adhesive sample was obtained in the same manner as in Example 1, and the test was performed in the same manner.

Comparative Examples 1 to 4 In Example 1, a sheet having a thickness of 4 mm made of a rubber compound G or E using A or B having the composition shown in Table 1 as a treatment liquid, using D or E as an RFL liquid. An adhesive sample was obtained in the same manner as in Example 1 except that the sample was used, and a test was conducted in the same manner.

Example 3 An adhesive was prepared in the same manner as in Example 1 except that the treatment liquid C in Example 1 was used, as shown in Table 5, in which the weight ratio of the epoxy compound / liquid chloroprene rubber was variously changed. Samples were obtained and tested as well. The results are shown in Table 5.

Example 4 An adhesive sample was obtained in the same manner as in Example 1 except that the type of the liquid rubber was changed as shown in Table 6 in the treatment liquid C in Example 1, and a test was conducted in the same manner. . The results are shown in Table 7.

Example 5 The same aromatic polyamide fiber cord as in Example 1
After being immersed in the treatment liquid C having the composition shown in the table, heat treatment was performed at 235 ° C. for 1 minute.

Next, RFL liquid D having the composition shown in Table 2 , An adhesive sample was obtained in the same manner as in Example 1 except that the resorcinol / formalin molar ratio was variously changed as shown in Table 8, and a test was conducted in the same manner. The results are shown in Table 8.

Effects of the Invention As described above, according to the method of the present invention, after treating an aromatic polyamide fiber with a solution containing an epoxy compound and a block polyisocyanate, it is treated with an RFL solution, and the unvulcanized rubber is treated. By the close vulcanization with the compound, the aromatic polyamide fiber and the various rubber compounds can be firmly bonded, and the range of the obtained bonded composite is excellent in bending fatigue resistance. Have.

Therefore, the method of the present invention can be used for applications requiring adhesive strength and bending fatigue resistance, for example, in dynamic products such as power transmission belts, conveyor belts, tires, etc. Suitable for bonding.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI // C08L 21:00 (56) References JP-A-4-33976 (JP, A) JP-A-3-227332 (JP, A JP-A-56-2156 (JP, A) JP-A-63-66382 (JP, A) JP-A-2-84585 (JP, A) JP-A-58-5243 (JP, A) JP-A-58-524 124631 (JP, A) JP 45-21594 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 5/00-5/24 C08L 21/00 D06M 15/693, 15/55

Claims (4)

(57) [Claims] 1. A method for bonding an aromatic polyamide fiber and a rubber compound, wherein the aromatic polyamide fiber comprises: (a) 100 parts by weight of an epoxy compound having at least one epoxy group in a molecule; A first step of treating with a solution containing 5 to 20 parts by weight of a blocked polyisocyanate, (b) a second step of treating with a resorcinol / formalin / rubber latex mixture, and (c) an unvulcanized rubber compound. A method for bonding an aromatic polyamide fiber and a rubber compound, comprising a third step of adhesion vulcanization. 2. The bonding method according to claim 1, wherein the liquid rubber is polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber or chloroprene rubber. 3. The bonding method according to claim 1, wherein the liquid rubber has an amino group, a hydroxyl group or a carboxyl group at a molecular terminal. 4. The bonding method according to claim 1, wherein prior to the first step, the aromatic polyamide fiber is treated with a solution of an isocyanate, an epoxy compound or a mixture thereof.