JPH04356547A - Fiber-reinforced rubber composition and method for producing the same - Google Patents

Abstract

PURPOSE:To obtain a fiber-reinforced rubber composition excellent in mechanical properties, fatique resistance, heat resistance and processability by chemically bonding NBR containing a specified antioxidant with a specified thermoplastic resin in the form of a short fiber through a coupling agent. CONSTITUTION:The title composition is obtained by dispersing 2-150 pts.wt. thermoplastic polyamide resin or thermoplastic polyester resin in the form of a short fiber in 100 pts.wt, acrylonitrile/butadiene copolymer rubber (NBR), adding 2-5 pts.wt. amine ketone and/or amine antioxidant (e.g. 2,2,4-trimethyl-1,2- bihydroquinoline polymer) to the mixture, and chemically bonding the NBR with the thermoplastic resin through 0.1-5 pts.wt., per 100 pts.wt. said resin, of coupling agent.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-reinforced rubber composition in which acrylonitrile-butadiene copolymer rubber (hereinafter abbreviated as NBR) is reinforced with short fibers of thermoplastic polyamide resin or thermoplastic polyester resin. The fiber-reinforced rubber composition of the present invention can be used alone or in combination with compounding agents such as vulcanizable rubber, fillers, plasticizers, and vulcanizing agents for sealing materials such as packing, O-rings, gaskets, and boots. ,
Hoses such as gasoline hoses, oil-resistant hoses, Freon gas hoses, rubber rolls such as printing rolls and dyeing rolls, belts such as oil-resistant belts, oil-resistant sponges, and heel and sole parts of shoes that require oil resistance. , oil-resistant diaphragms, brake linings, NBR adhesives, etc.

0002

BACKGROUND OF THE INVENTION NBR is a copolymer of acrylonitrile and butadiene, and is generally produced by emulsion polymerization. In addition, NBR has excellent oil resistance, excellent processability, and versatility such as being able to be vulcanized with sulfur, and the physical properties of the vulcanizate are also excellent, so it is widely used in various product fields. There is.

[0003] However, when NBR is used for these purposes, it may lack mechanical properties such as rigidity and strength, and heat resistance, and it is difficult to improve mechanical properties and heat resistance without impairing processability. desired.

The most common method for improving the mechanical properties of resins and rubbers is to add and blend inorganic fillers, carbon black, and the like. However, reinforcing with these usually requires the addition of a large amount, and the reinforcing effect is often insufficient. If the amount added is increased with the intention of achieving a greater reinforcing effect, fluidity and dispersibility may deteriorate, impairing processability.
On the contrary, it causes an extreme decrease in mechanical properties such as strength, elongation, and impact resistance, so there are limits to the amount of addition and reinforcing effect.

[0005] A method for more effective reinforcement is to use a fibrous reinforcing material. For example, various fiber-reinforced compositions have been studied and proposed by adding inorganic fibers such as glass and ceramics, or organic fibers such as cellulose, polyester, polyamide, and liquid crystal polymers to base resins and rubbers. . In these cases, it is possible to increase rigidity with a relatively small amount of addition, but dispersibility and fluidity deteriorate, resulting in rough skin and reduced workability of the molded product, as well as fatigue in situations involving large deformations. The problem is that it causes problems with sexuality. This means that the fibers are relatively thick (generally the diameter is 0
．． 01mm or more), because it is rigid, especially NB
The rubber that is reinforced like R is flexible, which is a crucial problem if you want to take advantage of this feature. Furthermore, since the fibers are thick, the surface area of the fibers is small at the same weight-based filling amount, and the adhesion to the rubber to be reinforced is insufficient, which is considered to exacerbate the above-mentioned problems.

Many technological developments have been made to overcome the various problems and difficulties mentioned above. For example, JP-A-59
-49246, JP 59-108046, JP 60-96630, JP 60-966
As seen in JP-A No. 31 and JP-A-64-51449, ozone resistance and heat aging resistance are improved by combining NBR or modified NBR with a polyamide resin. As shown in the aforementioned patent publication, N
Although the combination of BR and polyamide resin improves ozone resistance and heat aging resistance, it does not satisfy recent demands for improved performance of rubber parts for automobiles.

In other words, it is important to improve the heat resistance of rubber parts and to reduce the size of the rubber parts in order to improve the performance of the engine and to cope with the increase in heat around the engine due to the reduction of the gap in the engine hood. In order to reduce weight in order to reduce fuel consumption, it is important to develop rubber with high elastic modulus and high strength. It cannot be said that the rubber compositions disclosed in the above-mentioned patent publications are sufficient to meet these demands.

[0008] Also, Japanese Patent Application Laid-open No. 52-105952,
JP-A-62-184037, JP-A-2-1152
No. 64 discloses an attempt to improve processability, mechanical properties, and heat aging resistance by melt-blending NBR or modified NBR with polyamide resin and subjecting it to dynamic vulcanization using an organic peroxide or the like. be. However, since the above composition is partially crosslinked, there are few problems when molding it as such, but when blending it with other rubbers, resins, fillers, etc., it is extremely difficult to mix uniformly, making it difficult to achieve the intended purpose. No performance improvement can be expected.

Furthermore, attempts have been made to improve durability by combining NBR with polyamide fibers, etc. For example, JP-A-62-104848, JP-A-62-1
No. 06146 and Japanese Unexamined Patent Publication No. 159827/1987 disclose a technique for improving heat aging resistance, durability, etc. by compositing hydrogenated NBR and polyamide fiber.

However, in these techniques, the adhesion between the matrix rubber and the fibers is insufficient, which limits their use in high strain regions, which are important for rubber properties, and the durability in these regions is insufficient. Furthermore, since the diameter of the fibers is larger than that of fillers that are generally blended into rubber, stress concentration occurs in areas where strain occurs, and fatigue failure due to repeated strain is likely to occur. Furthermore, due to the large diameter of the fibers, it is difficult to uniformly disperse the fibers in the rubber matrix, which often causes major problems in terms of processing and product performance. The various problems described above are not solved even when thermoplastic polyester is used instead of thermoplastic polyamide.

Next, regarding a fiber-reinforced rubber composition in which fine fibrous thermoplastic polyamide resin or thermoplastic polyester resin is used as a reinforcing material, and a method for producing the same, particular details are given when the matrix rubber is an ethylene-propylene-diene copolymer rubber. For chlorosulfonated polyethylene rubber as the matrix rubber, see JP-A No. 1-242648, and for chlorinated polyethylene as matrix rubber, see JP-A No. 2-251.
It is disclosed in Japanese Patent No. 550.

[0012] Using the method for producing a fiber-reinforced rubber composition described above, an attempt was made to produce a fiber-reinforced rubber composition using NBR as a matrix rubber. However, NBR has become gay,
A strong chemical bond could not be formed at the interface between the thermoplastic polyamide resin or thermoplastic polyester resin and NBR.

[0013] What is required for the composite of NBR and thermoplastic resin is: (1) improved heat resistance, high modulus of elasticity, and high strength; (2) ease of blending with other rubbers, resins, fillers, etc.; ■Matrix rubber and thermoplastic resin are strongly chemically bonded at the interface, and ■thermoplastic resin dispersion forms a fine fibrous form.

The object of the present invention is to satisfy the above-mentioned requirements, solve the problems of the prior art, and create a fiber-reinforced NBR fiber reinforced with excellent mechanical properties, fatigue resistance, heat resistance, and processability. An object of the present invention is to provide a composition and a method for producing the same.

[0015]

[Means for Solving the Problem] As a result of intensive studies to achieve the above-mentioned object, the present inventors have developed a method using thermoplastic polyamide resin or thermoplastic polyester resin in the form of fine fibers as a reinforcing material. We have discovered a new NBR fiber-reinforced composition and a method for producing the same, and have arrived at the present invention.

The present invention includes (a) 100 parts by weight of acrylonitrile-butadiene copolymer rubber, and (b) 2 to 150 parts by weight of thermoplastic polyamide resin or thermoplastic polyester resin.
Part by weight is dispersed in the form of short fibers, (c) amine/ketone type and/or amine type anti-aging agent 0.2-5
(d) 100 parts by weight of the above thermoplastic resin
The present invention provides a fiber-reinforced rubber composition characterized in that the copolymer rubber and the thermoplastic resin are chemically bonded by 0.1 to 5 parts by weight of a coupling agent.

[0017] Furthermore, after melt-kneading NBR, a thermoplastic polyamide resin or a thermoplastic polyester resin, an amine/ketone type and/or amine type anti-aging agent, and a coupling agent at a temperature higher than the melting point of the thermoplastic resin, , a method for producing a fiber-reinforced rubber composition characterized by spinning and winding.

[0018] NBR used in the present invention is generally 1,3-
Manufactured by emulsion polymerization of butadiene and acrylonitrile. As auxiliary raw materials, emulsifiers, polymerization initiators, molecular weight regulators, electrolytes, polymerization terminators, stabilizers, etc. are used. N
The amount of bound acrylonitrile in BR is generally 50 to 15%, and can be used depending on the purpose.

The thermoplastic polyamide resin used in the present invention is a thermoplastic nylon capable of forming fibers, such as nylon-6, nylon-11, nylon-12, nylon-610, nylon-612, and nylon-6/66. polyamides and mixtures thereof, including copolymers such as The molecular weight of the polyamide used is preferably 8,000 or more, and its melting point is preferably in the range of 150 to 240°C.

The thermoplastic polyester resin used in the present invention is a fiber-formable thermoplastic polyester, such as polyesters containing polybutylene terephthalate, polycarbonate, and mixtures thereof.

In the composition of the present invention, the proportion of fiber-shaped thermoplastic polyamide resin or thermoplastic polyester resin dispersed in NBR is 2 to 150 parts by weight based on 100 parts by weight of NBR. If the proportion of the thermoplastic resin is less than 2 parts by weight, no improvement in mechanical properties will be observed, while if it is more than 150 parts by weight, the rigidity will be high, but the strength and elongation will be extremely low, and the kneading processability will be poor. I don't like it because it makes it worse.

In the composition of the present invention, the thermoplastic polyamide resin or thermoplastic polyester resin dispersed in NBR is in the form of fine fibers. That is,
Most of the above thermoplastic resin has a length of 0.05 mm or more and a maximum diameter of 0.00 mm in a cross section perpendicular to the longitudinal direction.
It shows short fibrous morphology of 5 mm or less. There is no problem even if small amounts of particles, rods, or films other than this form are included, but if they are in large quantities, they will have a negative effect on the reinforcing effect, dispersibility, and fluidity, deteriorating processability and product appearance, as well as increasing the strength of the product. This is not preferable because it causes a decrease in fatigue resistance.

The anti-aging agent used in the present invention is an amine/ketone type and/or an amine type anti-aging agent. For example, 2,2
, 4-trimethyl-1,2-dihydroquinoline polymer,
6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, trimethyl-dihydroquinoline derivative,
Diphenylamine-acetone high-temperature condensate, diphenylamine-aniline-acetone low-temperature condensate, phenyl-β-
Naphthylamine-acetone condensate, phenyl-α-naphthylamine, phenyl-β-naphthylamine, N,N'
-di-β-naphthyl-p-phenylenediamine, N,N
'-Diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N
, N'-diallyl-p-phenylenediamine, N-phenyl-N'-(1,3 dimethylbutyl)-p-phenylenediamine, N,N'-di(1,4 dimethylpentyl)
-p-phenylenediamine, p-(p-toluenesulfonylamide)-diphenylamine, diphenylamine derivatives and mixtures thereof.

In the composition of the present invention, the proportion of amine/ketone type and/or amine type antiaging agent contained in NBR is 0.2 parts by weight per 100 parts by weight of NBR.
~5 parts by weight. This anti-aging agent has the effect of improving the thermal stability of NBR during the process of producing the composition of the present invention, and if the proportion of the anti-aging agent is less than 0.2 parts by weight, during the production of the composition. NBR gels and the above-mentioned thermoplastic resin does not take the form of short fibers, making it uneconomical if the amount exceeds 5 parts by weight.

Coupling agents used in the present invention include silane coupling agents, titanate coupling agents, unsaturated carboxylic acids, and mixtures thereof. Examples of the silane coupling agent include vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-
epoxycyclohexyl)ethyltrimethoxysilane,
γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β-
(aminoethyl)-aminopropyltrimethoxysilane, N-β-(aminoethyl)aminopropylmethyldimethoxysilane, N-β-(aminoethyl)-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, N- Examples include phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and the like. Among these silane coupling agents, those having an amino group, an epoxy group, or a methacrylic group are particularly preferably used.

Examples of titanate coupling agents include isopropylisosteroyl titanate, isopropyltri(N-aminoethyl-aminoethyl)titanate, and tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanate. , bis(dioctylpyrophosphate)oxyacetate titanate, isopropyl isostearoyl diacryl titanate, isopropyl dimethacrylylisostearoyl titanate, and the like. Among these titanate coupling agents, those having an amino group, an epoxy group, or a methacrylic group are particularly preferably used.

Examples of unsaturated carboxylic acid coupling agents include α,β-unsaturated carboxylic acids, alicyclic unsaturated carboxylic acids, alkenyl carboxylic acids, and derivatives thereof such as acrylic acid, methacrylic acid, maleic acid, Fumaric acid, itaconic acid, vinylbenzoic acid, vinyl phthalic acid, maleic anhydride, itaconic anhydride, endo-bicyclo(2,
2,1)-5-heptene-2,3-carboxylic acid, cis-
Examples include 4-cyclhexene-1,2-carboxylic acid, octadecenylsuccinic acid, and their anhydrides, esters, metal salts, and other derivatives. Of these,
maleic acid, fumaric acid, itaconic acid, vinylbenzoic acid,
Vinyl phthalic acid, maleic anhydride, and itaconic anhydride are particularly preferably used.

In the composition of the present invention, a coupling agent is contained in an amount of 0.1 to 5 parts by weight per 100 parts by weight of thermoplastic polyamide resin or thermoplastic polyester. This coupling agent acts to increase the adhesion between NBR as a continuous phase and the thermoplastic resin in the form of fine short fibers as a dispersed phase. Also,
This coupling agent also exhibits the effect of improving the dispersion of the thermoplastic resin in NBR. These effects are effective for improving the mechanical properties, fatigue resistance, heat resistance, and processability of NBR made of the thermoplastic resin in the form of fine short fibers.

The fiber-reinforced rubber composition of the present invention may contain appropriate amounts of commonly used antiaging agents, plasticizers, fillers, processing aids, colorants, and the like. The fiber-reinforced rubber composition of the present invention contains 100 parts by weight of NBR, a thermoplastic polyamide resin or a thermoplastic polyester resin, and an amine.
A ketone-based and/or amine-based anti-aging agent and a coupling agent are kneaded at a temperature equal to or higher than the melting point of the thermoplastic resin to obtain a kneaded product having NBR as a continuous phase and the thermoplastic resin as a dispersed phase, and the kneading is performed. The product can be manufactured by a method in which the thermoplastic resin is stretched under conditions where it can be easily plastically modified.

NBR, thermoplastic polyamide resin or thermoplastic polyester resin, amine/ketone type and/or
Alternatively, the amine anti-aging agent and coupling agent can be kneaded using ordinary melt-kneading equipment for rubber and plastics, such as a Brabender Plastograph, Banbury mixer, kneader, single-screw or twin-screw extruder, etc. , preferably for 1 to 15 minutes. If the kneading is carried out at a temperature lower than the melting point of the thermoplastic resin used, fine dispersion of the thermoplastic resin will not be possible, and the desired fiber-reinforced rubber composition will not be obtained.

Stretching performed after kneading is an operation necessary to make the thermoplastic resin dispersed in the kneaded material into a preferable fine short fiber form. This can be carried out by roll rolling, by drawing the extrudate from an extruder by applying a draft, or by applying heat and tension to the extrudate and stretching it. The stretching force applied to the thermoplastic resin varies depending on the stretching method, but in any method, conditions such as temperature and speed are selected so that the thermoplastic resin can be easily deformed. The stretching ratio is preferably 2 or more.

The amount of the coupling agent used is 0.1 to 5 parts by weight, preferably 0.1 to 5 parts by weight, per 100 parts by weight of the thermoplastic resin.
It is 2 to 3 parts by weight. If the amount of the coupling agent exceeds the above upper limit, gelation of NBR and the above-mentioned thermoplastic resin will occur, resulting in poor dispersion and morphology of the thermoplastic resin. If the amount of the coupling agent is less than the lower limit, the adhesion between the NBR as a continuous phase and the thermoplastic resin in the form of fine short fibers as a dispersed phase will not be sufficient, and the thermoplastic resin in the NBR will not have sufficient adhesion. The dispersibility of the resin is also poor. Therefore, the mechanical properties, fatigue resistance, heat resistance, and workability of NBR are not improved.

According to the production method of the present invention, NBR forming a continuous phase has a fine short fiber-like form, that is, most of them have a length of 0.05 mm or more and in a cross section perpendicular to the longitudinal direction. A fiber-reinforced rubber composition in which the thermoplastic resin in the form of short fibers with a maximum diameter of 0.005 mm or less is finely dispersed can be obtained.

The fiber-reinforced rubber composition of the present invention can be used as is. Alternatively, if necessary, the thermoplastic resin may be blended with additional NBR or a resin or rubber having good compatibility with NBR, and the proportion of the thermoplastic resin may be adjusted before use. Further, it is used after crosslinking if necessary. Its uses include rubber hose materials, sealing materials,
NBR is used in various product fields such as rubber belts, rubber rolls, footwear, oil-resistant diaphragms, brake linings, automotive rubber parts, electrical rubber parts, and as a modifying material for phenolic resins and PVC resins. It is especially suitable for use in product fields that require NBR with excellent mechanical properties, fatigue resistance, heat resistance, and workability.

[0035]

Effects of the Invention The fiber-reinforced rubber composition of the present invention has particularly excellent mechanical properties such as rigidity and strength, fatigue resistance, and heat resistance.
It also has excellent workability.

[0036]

EXAMPLES The fiber-reinforced rubber composition of the present invention and the method for producing the same will be specifically explained below using Examples and Comparative Examples. Note that all parts are based on weight. Some of the raw materials used in the following examples are shown in Table 1.

[0037]

[Table 1]

Example 1 Each raw material with the composition shown in Table 2 was charged into a Brabender Plastograph set at 230°C and 50 rpm.
Kneaded for a minute. The obtained kneaded material is 2 mm in diameter and 4 m in length.
The mixture was supplied to a 20 mm screw extruder equipped with a nozzle having a small hole of m, and extruded at 230° C. into a string, which was then drawn at a drawing ratio of 2 to obtain a fiber-reinforced rubber composition.

The dispersion state of the thermoplastic resin in the obtained fiber-reinforced rubber composition was evaluated visually and tactilely in four stages. Further, the morphology of the resin component extracted using toluene was observed using a scanning electron microscope and evaluated in four stages. The results are shown in Table 2.

Evaluation of the dispersion state of thermoplastic resin◎
Excellent (fine dispersion, no bias) ○ Good △ Insufficient × Bad

Evaluation of the morphology of thermoplastic resin ◎ Excellent (fine short fiber-like morphology) Good (mostly fine short fiber-like morphology) △ Insufficient (maximum diameter of cross section is 0.005 mm or more, long (Most have a diameter of 0.05 mm or less) × Bad (Many lumps)

[0042]

[Table 2]

Furthermore, the following analysis was performed on the obtained fiber-reinforced rubber composition in order to examine the degree of chemical bonding between NBR and the thermoplastic resin.

[0044] 2 g of fiber reinforced rubber composition was mixed with 200 g of toluene.
ml at 80° C. to dissolve the rubber component in the reinforced rubber composition, and the resulting slurry was centrifuged to separate into a solution portion and a precipitate portion. After repeating the above toluene dissolution and centrifugation operations for the precipitated portion seven times, the precipitated portion was dried to obtain a fibrous material of thermoplastic resin. The fibrous material was dissolved in a mixed solvent of phenol and orthodichlorobenzene and analyzed by 1H nuclear magnetic resonance spectrum (NMR), and from the NMR chart, the peak of the methine group adjacent to CN caused by NBR, the thermoplasticity Due to resin,
For the peaks of methylene groups, calculate their areas and N
The grafting rate of BR and thermoplastic resin was calculated. The results are shown in Table 2.

Comparative Example 1 Brabender plastograph conditions were 150°C, 50r
pm, the temperature of the 20 mm extruder was 150° C., and the same operation as in Example 1 was performed except that the stretching ratio was set to 2. The results are shown in Table 2.

Examples 2 to 3, Comparative Example 2 The same operations as in Example 1 were carried out except that the raw materials having the composition shown in Table 2 were used. The results are shown in Table 2.

Example 4, Comparative Examples 3 to 6 The same operations as in Example 1 were carried out except that the raw materials having the composition shown in Table 3 were used. The results are shown in Table 3.

[0048]

[Table 3]

Examples 5 to 8, Comparative Example 7 The same operations as in Example 1 were carried out except that the raw materials having the composition shown in Table 4 were used. The results are shown in Table 4.

[0050]

[Table 4]

Examples 9 to 13 The same operations as in Example 1 were carried out except that the raw materials having the composition shown in Table 5 were used. The results are shown in Table 5.

[0052]

[Table 5]

Example 14 Each raw material having the composition shown in Table 6 was made into a mold with a diameter of 2 mm and a length of 4 mm.
The mixture was fed into a 30 mm screw extruder equipped with a nozzle having small holes, and the mixture was kneaded at 230°C for about 5 minutes, extruded into a string, and drawn at a stretching ratio of 3 to obtain a fiber-reinforced rubber composition. Ta. The obtained fiber-reinforced rubber composition was evaluated in the same manner as in Example 1. The results are shown in Table 6.

[0054]

[Table 6]

Examples 15 to 18 As shown in Table 6, the same operations as in Example 1 were carried out except that the type of coupling agent was changed. Table 6 shows the results.
Shown below.

Comparative Examples 8 and 9 NBR, various compounding agents, and vulcanizing agents having the composition shown in Table 7 were blended using a 6-inch roll at 80°C, placed in a sheet mold, and press-vulcanized at 155°C for 10 minutes. and the thickness is 2
A sheet-like vulcanizate of mm was obtained. This vulcanizate was punched into the shape of a JISI dumbbell to obtain a normal condition test piece, and punched into a B shape to obtain a tear test piece.

Regarding the above normal test piece, JIS K63
Measurement of 100% modulus, breaking strength, and breaking elongation by tensile test in accordance with J.
The tear strength was measured by a tear test according to ISK6301. Next, the test piece was exposed to an air atmosphere at 120°C for 72 hours using a Gya aging tester, and then
The dumbbells were measured in the same manner as the above tensile test, and the heat resistance was evaluated based on the retention rate with respect to the measured value before the heat aging test. In addition, 0 to 100% to the above normal test piece
The fatigue resistance was evaluated by repeatedly elongating the material 1 million times and measuring the retention rate of 100% modulus. Furthermore, in order to comparatively evaluate the processability, the sheet surface condition of the vulcanizate was visually and tactually inspected, and a four-level evaluation was performed. The results are shown in Table 7.

Evaluation of sheet surface condition of vulcanizate◎
Excellent (completely smooth) ○ Good (almost smooth) △ Unsatisfactory (rough skin) × Poor (rough rough skin)

Examples 19 to 21 The fiber-reinforced rubber compositions obtained in Examples 1, 2, and 12 were used as masterbatches, and the amounts of thermoplastic resin were adjusted to 5 or 10 parts based on 100 parts of NBR in Table 7. The compositions shown in Table 1 were blended, and the same operations as in Comparative Example 8 were carried out. The results are shown in Table 7.

[0060]

[Table 7]

Comparative Example 10, Examples 22 and 23 The fiber-reinforced rubber compositions obtained in Comparative Example 10 and Examples 12 and 18, respectively, were used as a masterbatch, and the thermoplastic resin was 5 parts per 100 parts of NBR. The compositions shown in Table 8 were formulated as shown in Table 8, and the same operations as in Example 19 were carried out. The results are shown in Table 8.

[0062]

[Table 8]

Comparative Example 11 NBR was mixed with cut nylon fibers in the composition shown in Table 8, and the same procedure as in Comparative Example 8 was carried out. The results are shown in Table 8.

Claims (4)

[Claims] Claim 1: (a) 100 parts by weight of acrylonitrile-butadiene copolymer rubber, (b) 2 to 150 parts by weight of thermoplastic polyamide resin or thermoplastic polyester resin dispersed in the form of short fibers, (c) amine - Contains 0.2 to 5 parts by weight of a ketone-based and/or amine-based anti-aging agent, and (d) 0.1 to 5 parts by weight of a coupling agent per 100 parts by weight of the thermoplastic resin. A fiber-reinforced rubber composition characterized in that a copolymer rubber and the above thermoplastic resin are chemically bonded. [Claim 2] Short fibers made of thermoplastic polyamide resin or thermoplastic polyester resin have a length of 0.05.
mm or more, and the maximum diameter in a cross section perpendicular to the longitudinal direction is 0.005 mm or less
The fiber-reinforced rubber composition described in 2. 3. The fiber reinforced rubber composition according to claim 1, wherein the coupling agent comprises a silane coupling agent, a titanate coupling agent, and an unsaturated carboxylic acid. 4. Acrylonitrile-butadiene copolymer rubber, thermoplastic polyamide resin or thermoplastic polyester resin, amine/ketone type and/or amine type anti-aging agent, and coupling agent at a temperature higher than the melting point of the thermoplastic resin. A method for producing a fiber-reinforced rubber composition, which comprises melt-kneading at a temperature, then spinning and winding.