JPH0216138A - Rubber composition for hose - Google Patents

Abstract

PURPOSE:To obtain the title composition which, when extruded, can give a reinforced rubber hose used as an automotive water hose, excelling in heat resistance, heat aging characteristics, modulus and burst strength and having a smooth surface skin by graft-bonding a short fiber to EPDM and dispersing another short fiber thicker than the former in the resulting EPDM. CONSTITUTION:A short fiber (B) (average fiber diameter of 0.1-1.5mum) of a thermoplastic polyamide, a polyester or the like is graft-bonded to a continuous phase of an ethylene/alpha-olefin/diene copolymer rubber (A) (e.g., EPDM, desirably, the olefin is propylene or butene-1, and the diene is ethylidenenorbornene) by using 0.2-4pts.wt., per 100pts.wt. short fiber, silane or titanate coupling agent. Another short fiber (C) of an average fiber diameter of 2-30mum and a fiber length of 0.5-10mm is dispersed in component A to form a rubber composition for hoses. The mixing ratio among these components is desirably such that the amount of A to 100pts.wt., that of B is 5-40pts.wt. and that of C is 3-30pts. wt., while that of the sum of B and C is 0-50pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The rubber composition of the present invention is for use in manufacturing water hoses for automobiles. By extrusion molding the rubber composition of the present invention, it is possible to produce an automobile water hose that has excellent heat resistance, heat aging resistance, elastic modulus, and bursting strength, and has a smooth surface.

[Prior art 1] Automotive water hoses are used in the cooling and heating systems of automobiles.

These rubber hoses include non-reinforced rubber hoses without a reinforcing layer, internally reinforced rubber hoses with a reinforcing layer between the inner and outer rubber of the hose, and externally reinforced rubber hoses with a reinforcing layer on the outer surface of the hose. Reinforced rubber hoses have traditionally been used.

Non-reinforced rubber hoses have been manufactured by molding a rubber compound containing no fibers into a pipe shape using an extrusion molding machine and vulcanizing the pipe.

On the other hand, a medium-reinforced rubber hose has an inner rubber layer formed by molding a rubber compound into a pipe shape using an extrusion molding machine.
It has been manufactured by knitting fibers or wrapping plain-woven cloth as a reinforcing layer, covering the surface with an outer rubber layer, and vulcanizing it. Externally reinforced rubber hoses have been manufactured by knitting fibers onto the inner rubber layer to form a reinforcing layer, which is then further vulcanized.

Reinforced rubber hoses such as internally reinforced rubber hoses and externally reinforced rubber hoses can withstand much higher pressure than non-reinforced rubber hoses, so these reinforced hoses have been used in areas where pressure resistance is required.

[Problems with the prior art] Unlike non-reinforced rubber hoses, which are manufactured by extrusion molding a rubber compound, internally reinforced rubber hoses and externally reinforced rubber hoses are manufactured using a complicated manufacturing process. The disadvantage was that productivity was lower than that of rubber hoses.

In addition, the internally reinforced rubber hoses and externally reinforced rubber hoses that have been conventionally used for automobile water hoses do not have sufficient adhesion between the reinforcing agent such as fiber or cloth and the rubber, so they cannot be used in high temperatures for long periods of time. If this happens, cracks may occur near the interface between the reinforcing agent and the rubber. The occurrence of such cracks is a serious problem because it leads to liquid leakage and damage to the hose.

In recent years, with improvements in fuel efficiency and performance of automobiles, engine temperatures have increased, and the temperature around the engine has come to exceed 100°C. Along with this, water hoses for automobiles have also been exposed to higher temperatures, and are now required to have heat resistance and heat aging resistance. Therefore, solutions to the above problems have been increasingly demanded.

A method of extrusion molding a mixture of rubber and short fibers in order to solve the low productivity of conventional intermediately reinforced rubber hoses and externally reinforced rubber hoses and to manufacture reinforced rubber hoses with excellent heat resistance and heat aging resistance. has been attempted.

First, a method of extrusion molding a mixture of rubber and short cellulose fibers was attempted (Japanese Patent Publication No. 53-1426
9, Special Publication No. 57-54050, Special Publication No. 5B-29231
). However, since the reinforced rubber hose obtained by this method uses short cellulose fibers, it has insufficient heat resistance and heat aging resistance, which poses a problem for use in recent high-performance automobile engines.

Next, ethylene propylene polyene copolymer rubber,
A method was attempted in which a short fiber-reinforced rubber composition containing polyamide short fibers with this rubber grafted onto the fiber surface, ethylene-propylene copolymer rubber, and an antioxidant was extruded into a pipe 4k (Japanese Patent Application Laid-Open No. 62-25685
0), ethylene propylene polyene copolymer rubber is
In addition to being a rubber that originally has excellent heat resistance and heat aging resistance.

It is strongly grafted to polyamide short fibers on the fiber surface. Therefore, the reinforced rubber hose obtained by this method exhibited superior heat resistance, heat aging resistance, high elastic modulus, and bursting strength compared to conventional hoses. However, this hose had a problem with its appearance as the surface was somewhat rough.

[Technical means for solving the problems] The rubber composition of the present invention is suitable for manufacturing reinforced rubber hoses by extrusion molding. By extrusion molding the rubber composition of the present invention, heat resistance, aging,
This reinforced rubber hose, which has excellent elastic modulus and bursting strength and has a smooth surface, is particularly suitable for use in automobile water hoses.

The rubber composition for a hose of the present invention has the following composition. That is, (a) Ethylene/α-olefin/diene copolymer rubber (hereinafter abbreviated as EPDM) (b) The average fiber diameter is 0.1 to 1.5 μm, and the fiber surface is coated with the above EPDM and a coupling agent. (c) short fibers that are graft-bonded; and (c) an average fiber diameter of 2 to 30 tIm and a fiber length of 0.
It is composed of short fibers that are 5-10 nm+. (a) the components form a continuous layer;
The component and (c) component are uniformly dispersed in the (a) component.

The proportions of each component are (a) per 100 parts by weight of component;
It is preferable that the component is 5 to 40 parts by weight, the component (c) is 3 to 30 parts by weight, and the total amount of component (b) and component (c) is 10 to 50 parts by weight.

If component (c) is less than 5 parts by weight per 100 parts by weight of component (a), only a reinforced rubber hose with inferior bursting strength and heat aging resistance will be obtained.If component (b) exceeds 40 parts by weight, the surface Only reinforced rubber hoses with rough edges and poor appearance can be obtained.

If the amount of component (c) is less than 3 parts by weight per 100 parts by weight of component (a), only a reinforced rubber hose whose initial elastic modulus is not significantly improved can be obtained. When such a reinforced rubber hose is subjected to a pressure test, it shows a large change in outer diameter. Such reinforced rubber hoses are not preferred as water hoses for automobiles.

If the amount of component (c) exceeds 30 parts by weight, only a reinforced rubber hose with a rough surface will be obtained.

The total amount of component (b) and component (c) is 100% of component (a)
When the amount is less than 10 parts by weight, only a reinforced rubber hose with a low initial elastic modulus can be obtained. If it exceeds 50 parts by weight, only a reinforced rubber hose with a rough surface will be obtained.

Commercially available products can be used as component (a). However, those in which the α-olefin is propylene or butene-1 are preferred. The diene is ethylidene norbornene, 1
．． Preferred are 4-hexadiene, dicyclopentadiene and the like.

Component (b) needs to have an average fiber diameter in the range of 0.1 to 1.5 μm. If the average fiber diameter is less than 0.1 μm, the initial elastic modulus of the reinforced rubber hose will be low and the burst strength will also be low. When the average fiber diameter is larger than 1.5 μm, the surface of the reinforced rubber hose becomes rough and the appearance deteriorates.

(b) Ingredients include nylon 6, nylon 66, nylon 12, nylon 610, nylon 611, nylon 61
2. Short fibers such as thermoplastic polyamides such as nylon 666, thermoplastic polyesters such as polybutylene terephthalate and polyethylene terephthalate, and polycarbonate are preferably used.

In addition, component (b) needs to be firmly grafted to component (a) on the fiber surface. If it is not grafted to component (a), the bursting strength of the hose will be low.

A coupling agent is used to generate a graft bond with component (a). The amount of coupling agent used is
The amount is 0.2 to 4 parts by weight based on 100 parts by weight of the short fibers. If the amount of the coupling agent used is less than 0.2 parts by weight, sufficient graft bonding will not be obtained, and if it is more than 4 parts by weight, the coupling agent will be wasted.

As such a coupling agent, a silane coupling agent, a titanate coupling agent, an unsaturated carboxylic acid coupling agent, or a mixture thereof is used.

Among these coupling agents, particularly preferred are those having an amino group, an epoxy group, or a methacrylic group.

Examples of such coupling agents include the following.

Examples of the silane coupling agent include vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane,
γ-methacryloxypropyltrimethoxysilane, β-
(3,4-epoxycyclohexyl)ethyltrimethoxysilane, T-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyljethoxysilane, N-β-(aminoethyl)-aminopropyltrimethoxysilane, N -β-(aminoethyl)-aminopropylmethyldimethoxysilane, N-β-(aminoethyl)
Examples include -aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane.

Examples of titanate coupling agents include isopropyl isostearoyl titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, and tetra(2,
2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanate, bis(dioctylpyrophosphate)oxyacetate titanate, isopropyltrioctanoyltitanate, isopropylisostearoyldiacryltitanate, isopropyldimethacrylisostearoyltitanate, etc. Examples include:

As unsaturated carboxylic acid coupling agents, 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)-
Examples include 5-hebutene-2,3-carboxylic acid, cis-4-cyclohexene-1,2-carboxylic acid, octadecenylsuccinic acid, and derivatives thereof such as anhydrides, esters, and metal salts. .

The short fibers of component (c) need to have an average fiber diameter of 2 to 30 μm. When the average fiber diameter is less than 2 μm,
Only reinforced rubber hoses with low initial elastic modulus can be obtained. 30
If it is larger than μm, the surface of the reinforced rubber hose will become rough. Also, the fiber length must be 0.5 to 10 mm. If the fiber length is less than 0.5 mm, the initial elastic modulus and tensile strength at break of the reinforced rubber hose will be low. If the fiber length is greater than 10 mm, it will be difficult to uniformly disperse the fibers in the rubber composition, and the mechanical properties of the reinforced rubber hose after vulcanization will vary greatly.

Component (c) is preferably short fibers of thermoplastic organic fibers such as polyamide fibers, polyester fibers, polyacrylic fibers, and polyvinyl alcohol fibers. Fibers obtained by regrafting acrylic acid, vinyl pyridine, maleic anhydride, maleic anhydride, etc. to these fibers by irradiation with radiation may also be used. In addition, the fiber surface can be treated with RFL treatment using latex such as chlorosulfonated polyethylene latex or ethylene-propylene-diene copolymer rubber latex, or treated with silane coupling agent, titanate coupling agent, unsaturated carboxylic acid, etc. Treated products are also suitable. (c) By performing such surface treatment on component,
The affinity and adhesiveness with component (a) can be increased. This makes it possible to reduce permanent elongation of the reinforced rubber hose.

In addition to the above, inorganic fillers, softeners, processing aids, antioxidants, etc. may be added to the rubber composition of the present invention to form a rubber compound.

As the inorganic filler, those commonly added to rubber, such as carbon black, anhydrous silicic acid, hydrated silicic acid, synthetic silicic acid, and calcium carbonate, can be used.

The amount of the inorganic filler blended is preferably within 300 parts by weight per 100 parts by weight of component (a).

Softeners include paraffinic process oils, naphthenic process oils, aromatic process oils, petroleum resins, polymerized high-boiling light aromatic oils, paraffin, liquid paraffin, mineral oil softeners such as white oil, and cottonseed oil. , vegetable oil-based softeners such as rapeseed oil, palm oil, rosin, pine cool oil, etc.
Examples include sulfurized oils such as black soybean and white soybean, fatty acids such as ricinoleic acid, palmitic acid, stearic acid, and lauric acid, and fatty acid metal salts such as calcium stearate, barium stearate, and zinc stearate.

The blending amount of the softener is 2 parts by weight per 100 parts by weight of component (a).
The amount is preferably within 0.00 parts by weight.

Tackifiers and plasticizers are used as processing aids.

Tackifiers include coumaron/indene resin, phenol resin, terpene resin, synthetic terpene resin, aromatic hydrocarbon resin, aliphatic cyclic hydrocarbon resin, polybutene, actinic polypropylene, liquid polybutadiene, and Molecular weight butyl rubber or the like is used.

Examples of plasticizers include phthalic acid derivatives, isophthalic acid derivatives, tetrahydrophthalic acid derivatives, adipic acid derivatives, azelaic acid derivatives, maleic acid derivatives, fumaric acid derivatives, trimellitic acid derivatives, citric acid derivatives, itaconic acid derivatives, and oleic acid derivatives. acid derivatives, ricinoleic acid derivatives,
Stearic acid derivatives, fatty acid derivatives, sulfonic acid derivatives, phosphoric acid derivatives, glycol derivatives, glycerin derivatives,
Paraffin derivatives, epoxy derivatives, etc. can be used.

The blending amount of the processing aid is preferably within 20 parts by weight per 100 parts by weight of component (a). If it exceeds 20 parts by weight, the heat aging resistance of the reinforced rubber hose obtained by extrusion will be significantly reduced.

As antioxidants, aldol-α-naphthylamine, 2,2,4-)limethyl-1,2゜dihydroquinoline polymer, 6-nitogycy-2,24-trimethyl-1,2
-dihydroquinoline, phenyl-β-naphthylamine,
N-phenyl-No-isopropyl-p-phenylenediamine, diphenylamine derivatives, 2-mercaptobenzimidazole, 2-mercaptobenzimidazole zinc salt, amine aldehydes such as nickel dibutyldithiocarbamate, amine ketones, amines, imidazoles, dithiocarbamin Acid salts and the like are preferably used.

Other things that can be used include 2,6-
Examples include phenolic antioxidants such as di-t-butyl-4-methylphenol and styrenated phenol.

The amount of antioxidant added is preferably within 4 parts by weight per 100 parts by weight of component (a).

The rubber composition of the present invention and the rubber compound obtained by adding an inorganic filler, a softener, a processing aid, an antioxidant, etc. Like rubber, it can be vulcanized with sulfur or organic peroxides.

In the sulfur vulcanization method, powdered sulfur, precipitated sulfur, and highly dispersed sulfur are used as the vulcanizing agent, but the so-called low sulfur vulcanization method is recommended.

When sulfur is used as the vulcanizing agent, thiurams, thiazoles, dithiocarbamates, etc. can be used as the vulcanization accelerator, and metal salts, fatty acids, etc. can be used as the vulcanization aid.

In the organic peroxide vulcanization method, the vulcanizing agent contains 1 site of dicumyl belloni, 3, 1,1-di(1-butylperoxy),
3.5-1-limethylcyclohexane, di(t-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2
, 5-dimethyl 2,5-di(t-butylperoxy)hexyne, and other organic peroxides are used. Further, as the vulcanization aid, sulfur, oxime compounds, cyanurate compounds, methacrylic acid derivatives, maleimide compounds, etc. are used.

The rubber composition of the present invention can be produced by the method disclosed in Japanese Patent Application No. 62-12005.

First, a fiber-reinforced rubber consisting of part of component (a) and component (b) is prepared. After kneading an antioxidant and a tackifier as necessary with component (a), a resin such as thermoplastic polyamide, thermoplastic polyester, or polycarbonate is melt-kneaded at a temperature equal to or higher than the melting point of these resins. At this time, a coupling agent is also added to form a graft bond between the rubber and the resin. This melt-kneaded product is extruded at a temperature higher than the melting point of the resin and wound up while being stretched. Stretching is performed at a temperature lower than the melting point of the resin. By extrusion and stretching, the resin such as thermoplastic polyamide in the kneaded material becomes fine short fibers of component (b).

Furthermore, component (a) is added to the above fiber-reinforced rubber, and (c)
The rubber composition of the present invention can be obtained by adding and kneading the component short fibers. Carbon black, an inorganic filler, and a softener are kneaded into this composition as required. This composition is further kneaded with a vulcanizing agent, a vulcanization aid, a vulcanization accelerator, etc. to form a rubber compound.

The kneading needs to be carried out at a temperature lower than the melting point of the short fibers of components (b) and (c).

By extruding this rubber compound using a mandrel die disclosed in Japanese Patent Publication No. 53-14269 and then vulcanizing it, a reinforced rubber hose such as an automobile water hose can be manufactured.

[Effects of the present invention] A rubber compound using the rubber composition of the present invention can be molded into a reinforced rubber hose simply by molding with a mandrel die. Therefore, it is characterized in that it is easier to manufacture than conventional intermediately reinforced rubber hoses or externally reinforced rubber hoses.

Further, the reinforced rubber hose manufactured from the rubber composition of the present invention has an elastic modulus, breaking strength,
It has heat aging resistance, but the surface skin is much smoother.

[Example] Examples and comparative examples of the present invention are shown below. EPDM used in Examples and Comparative Examples is a commercially available product. This EPDM
was blended with short fiber-reinforced rubber made by our company, commercially available short fibers, etc. to make a rubber composition for hoses.

The short fiber-reinforced rubber manufactured by our company used in the production of rubber compositions for hoses in the present examples and comparative examples had an average fiber diameter of 0.1 to
Short fibers of 1.5 μm of nylon or polyester are firmly graft-bonded to EPDM via a coupling agent. The short fibers mentioned above are (
b) component, and EPDM corresponds to component (a) of the claim.
Corresponds to a part of the ingredients.

Commercially available nylon short fibers or polyester short fibers were used as the short fiber of component (c). Hereinafter, commercially available short nylon fibers subjected to RFL treatment with chlorosulfonated polyethylene latex will be referred to as short fibers A.

Further, short fiber B is the same nylon fiber as short fiber A, but is not surface-treated. Short fiber C is obtained by subjecting the surface of commercially available polyester fiber to the same surface treatment as short fiber A. This rubber composition contains an inorganic filler such as carbon black, a softener, a processing aid, an antioxidant, A rubber compound for hoses was prepared by adding sulfur, a vulcanization accelerator, etc.

The names, product names, and manufacturing company names of the raw materials used in the Examples and Comparative Examples are summarized in Table 1.

JSREP27 was used as the back rattan charcoal earth EPDM, and UBE FRR2000X was used as the short fiber reinforced rubber. JSREP
92.5 parts by weight of 27, 15 parts of UBEFRR2000X
Parts by weight (fiber amount is half 7.5 parts by weight), fiber diameter 12μ
10 parts by weight of short fiber A with a fiber length of 3 mm, 150 parts by weight of FEF carbon black, 100 parts by weight of process oil (Diana Process PW380), 5 parts by weight of zinc white, and 1 part by weight of stearic acid were added to a BR type Banbury mixer. It was kneaded with This kneaded material is further added with vulcanization accelerators CZ, TT, TS, and B.
1.5 parts by weight, 1 part by weight, 1.5 parts by weight of Z, respectively.
parts by weight and 1 part by weight of sulfur were blended using an open roll to prepare a rubber compound for a hose.

This rubber compound was supplied to a rubber extruder (45 mmφ), and a reinforced rubber hose was formed and drawn using an expanding mandrel die. The surface texture of the reinforced rubber hose after molding was visually evaluated and ranked in five stages: excellent, good, fair, and poor.

Next, the above-mentioned reinforced rubber hose was heated through a 160°
Vulcanization was performed under the conditions of C×30 minutes. A water pressure test was conducted on the reinforced rubber hose after vulcanization at room temperature, and the result was 5 kg/cd.
! The rate of change in outer diameter during pressurization and burst pressure were measured.

Next, the heat aging resistance of the above rubber compound was evaluated as follows. First, a vulcanized sheet having a thickness of two cylinders was prepared from the rubber composition for a hose. A No. 3 dumbbell was punched out from the sheet according to the method of JIS K6301, and the dumbbell was subjected to a tensile test to measure its breaking strength (Es+o). Next, No. 3 dumbbells separately punched out from the same sheet were heated at 150°C x 7.
After being exposed to an air atmosphere for 0 hours, a tensile test was conducted in the same manner as described above, and the breaking strength (E,) was measured. Calculate the value of (El /Ego) x 1o o,
It was determined that the closer this value was to 100, the better the heat aging resistance.

Table 2 shows the composition of the rubber compound of this example, and the evaluation results of outer diameter change rate, bursting pressure, and heat aging resistance.

A rubber compound for a hose was prepared in the same manner as in Example 1, except that the proportions of JSREP27, UBE FRR2000X, and short fiber A were changed, and molded into a reinforced rubber hose. This reinforced rubber hose was evaluated for surface texture, outer diameter change rate, burst pressure, and heat aging resistance. The composition and evaluation results of the rubber compound are shown in Table 2.

88 parts by weight of Mitsui EPT3090E as Kosei E P DM, UBE FRR2000X as short fiber reinforced rubber
40 parts by weight (fiber amount is half 20 parts by weight), short fiber A
A rubber compound for a hose was prepared in the same manner as in Example 1 except that 5 parts by weight of was used, and a reinforced rubber hose was molded.

The surface texture, outer diameter change rate, burst pressure, and heat aging resistance of the reinforced rubber hose were evaluated in the same manner as in Example 1. The composition and evaluation results of the rubber compound are shown in Table 2.

56″ 34 Mitsui EPT3090E, UBE FRR2000χ,
A rubber compound for a hose was prepared in the same manner as in Example 4, except that the proportions of short fibers A and A were changed, and molded into a reinforced rubber hose. This reinforced rubber hose was evaluated for surface texture, outer diameter change rate, burst pressure, and heat aging resistance in the same manner as in Example 1.

The composition and evaluation results of the rubber compound are shown in Table 2.

A sample was prepared in the same manner as in Example 3, except that Hokkai Kaiko short fiber A was not blended. The surface texture, outer diameter change rate, burst pressure, and heat aging resistance of the reinforced rubber hose were evaluated in the same manner as in Example 1.

The composition and evaluation results of the rubber compound are shown in Table 2. Samples were made in the same manner as in Example 1, except that JSREP27 was 100 parts by weight, short fiber A was 30 parts by weight, and UBE FRR was not blended. was prepared. The surface texture, outer diameter change rate, burst pressure, and heat aging resistance of the reinforced rubber hose were evaluated in the same manner as in Example 1. The composition and evaluation results of the rubber compound are shown in Table 2.

UBE FRR2000X instead of UBEF'RR
A sample was prepared in the same manner as in Example 2, except that 40 parts by weight of 7000X was used. The surface texture, outer diameter change rate, burst pressure, and heat aging resistance of the reinforced rubber hose were evaluated in the same manner as in Example 1. The composition and evaluation results of the rubber compound are shown in Table 2.

Misfortune, [LL-Stop Comparison ■ Knee-standing short fibers A with different fiber lengths were used (8 mm in Example 8, 0.3 mm in Comparative Example 9, and Comparative Example 1).
A sample was prepared in the same manner as in Example 2, except that the diameter was 15 mm. The surface texture, outer diameter change rate, burst pressure, and heat aging resistance of the reinforced rubber hose were evaluated in the same manner as in Example 1. Table 2 shows the composition and evaluation results of the rubber compound.
Shown below.

Samples were prepared in the same manner as in Example 2, except that short fiber B (Example 9) or short fiber C (Example 10) was used instead of Knee Emperor short fiber A. The surface texture, outer diameter change rate, burst pressure, and heat aging resistance of the reinforced rubber hose were evaluated in the same manner as in Example 1. The composition and evaluation results of the rubber compound are shown in Table 2.

111 6111 Short fibers A with different fiber lengths and fiber diameters were used (in Example 11, fiber diameter was 25 μm, fiber length was 6 (Foundation),
In Comparative Example 11, the fiber diameter was 50 μm and the fiber length was 6 + nm.)
A sample was prepared in the same manner as in Example 2 except for this. Surface texture, outer diameter change rate, burst pressure,
Evaluation of heat aging resistance was carried out in the same manner as in Example 1.

The composition and evaluation results of the rubber compound are shown in Table 2.

Claims (1)

[Scope of Claims] (a) a continuous layer consisting of ethylene/α-olefin/diene copolymer rubber; (b) an average fiber diameter of 0.1 to 1.5 μm; Short fibers graft-bonded by a ring agent, and (c) an average fiber diameter of 2 to 30 μm and a fiber length of 0.5
A rubber composition for a hose consisting of short fibers having a length of ~10 mm.