JP2001234445A - Cord for reinforcing rubber and fiber-reinforced rubber material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cord for reinforcing rubber, capable of developing excellent fatigue resistance by using a carbon fiber and a fiber-reinforced rubber material suitably usable as a reinforcing material for a rubber material such as tire, belt, hose, etc., by using the reinforcing cord. SOLUTION: This cord for reinforcing rubber is obtained by impregnating a carbon fiber bundle having >=1.7% elongation at break with a rubber latex- containing resin composition and has <=1,000 N/m initial inclination (dM/dy)y=0 of bending load M-flexure y curve by ASTM D885-76.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a tire, a belt,
The present invention relates to a rubber reinforcing cord which can be suitably used as a reinforcing material for various rubber materials such as hoses, and a fiber reinforced rubber material reinforced by such a rubber reinforcing cord.

[0002]

2. Description of the Related Art Fiber-reinforced rubber materials reinforced by rubber reinforcing cords are widely used in tires, belts, hoses and the like.

In general, these rubber materials are obtained by reinforcing a rubber-containing base material with a cord formed by applying an adhesive to a surface layer of a twisted reinforcing fiber bundle.

[0004] Carbon fibers have high strength and high elastic modulus, and are excellent in heat resistance and water resistance, but have a problem in that fatigue resistance to deformations such as elongation / compression deformation and bending deformation is poor. For this reason, a fiber reinforced rubber material reinforced with a rubber reinforcing cord using carbon fibers has generally been considered to have poor fatigue resistance.

As an attempt to solve such a problem, JP-A-60-181369 discloses a method of adhering a mixture of an epoxy compound and rubber latex to a carbon fiber bundle. Japanese Patent Application Publication No. JP-A-2005-64131 discloses a method of attaching a mixture of a phenol derivative and rubber latex to a carbon fiber bundle.

However, even with these methods, the fatigue resistance and the flexibility of the tire cord required for rubber materials such as tires, belts, hoses, etc. are still at an insufficient level.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rubber-reinforcing cord using carbon fiber, which exhibits excellent fatigue resistance, and a tire or belt using such a reinforcing cord. Another object of the present invention is to provide a fiber-reinforced rubber material that can be suitably used as a reinforcing material for a rubber material such as a hose.

[0008]

In order to solve the above problems, a rubber reinforcing cord according to the present invention has the following (1) to (5).
Either configuration of (3) is adopted. That is, (1)
A rubber reinforcing cord comprising a carbon fiber bundle having a breaking elongation of 1.7% or more and being substantially twisted, and (2) a carbon latex having a breaking elongation of 1.7% or more and a rubber latex A rubber reinforcement cord impregnated with a resin composition containing: a bending load M-deflection y curve initial gradient (dM / dy) y = 0 is 1000 according to ASTM D885-76.
A rubber reinforcing cord having a rubber composition of not more than N / m or (3) a carbon fiber bundle having a breaking elongation of 1.7% or more impregnated with a resin composition containing a rubber latex, This is a rubber reinforcing cord having a twist number of 10 turns / m or less according to JIS R7601.

Further, in order to solve the above problems, the fiber reinforced rubber material according to the present invention employs the following constitution. That is,
A fiber reinforced rubber material in which a base material containing rubber is reinforced by the rubber reinforcing cord.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a carbon fiber bundle used for a rubber reinforcing cord (hereinafter referred to as cord) has a breaking elongation of 1.7% or more, preferably 1.8% or more. Preferably, it is 1.9% or more. 1.
If it is less than 7%, the cord is likely to break when subjected to deformation due to excessive stress, and may not be used for applications such as tires and belts.

Further, the cord is substantially non-twisted. For example, the number of twists according to JIS R7601 is 10 times / m or less, preferably 7 times / m or less, and more preferably 5 times / m or less. If it exceeds 10 times / m, when the obtained fiber reinforced rubber material (hereinafter referred to as rubber material) is repeatedly deformed, the fatigue resistance may be reduced due to the rubbing of the single fibers.

In the present invention, the carbon fiber bundle is preferably impregnated with a resin composition containing rubber latex. By the impregnation of the resin composition, peeling at the interface between the cord and the rubber (hereinafter referred to as a cord / rubber interface) in the rubber material is prevented, and the fatigue resistance of the rubber material is improved.

Here, the rubber latex is a polymer in which a polymer is dispersed in water.
In the cord, since voids that impair fatigue resistance may be generated, when impregnating the resin composition containing rubber latex into the carbon fiber bundle, the moisture contained in the cord is removed by heating and drying or the like. Is good.

Further, the code according to the present invention is an ASTM
The initial gradient (dM / dy) y = 0 of the bending load M-deflection y curve according to D885-76 is 1000 N / m or less, preferably 900 N / m or less, more preferably 80 N / m or less.
It is preferably 0 N / m or less. If it exceeds 1000 N / m, the flexibility of the cord decreases, and when the rubber material is repeatedly deformed, the fatigue resistance may decrease due to concentration of stress.

Further, the carbon fiber bundle has a tensile strength of 4000 MPa or more, preferably 4400 MPa
a or more, more preferably 4800 MPa or more. When the pressure is less than 4000 MPa, when the rubber material receives an excessive stress, the cord is easily broken, and the tire,
It may not be used for applications requiring a high degree of fatigue resistance, such as belts.

In the carbon fiber bundle, the number of single fibers constituting the fiber bundle is 4,000 to 20,000, preferably 6,000 to 18,000, more preferably 8,000 to 1,000.
It is good to be 6000. If it is less than 4000, the reinforcing effect of the cord becomes insufficient, and the dimensional stability of the rubber material may decrease. If it exceeds 20,000, an unimpregnated portion of the resin composition is generated inside the cord, and Fatigue resistance may decrease.

Further, it is preferable that the single fibers constituting the carbon fiber bundle have a substantially perfect circular cross section.
If the shape is not substantially a perfect circle, but other shapes, for example, an oval shape, a bean shape, a three-leaf shape, etc., the cords are easily broken due to abrasion between the single fibers, and the fatigue resistance of the rubber material is reduced. May drop.

Here, "substantially perfect circular" means that the cross section of the single fiber is defined by the ratio (= R / r) of the radius R of the circumscribed circle to the radius r of the inscribed circle. The degree of deformation (the measuring method will be described later) is in the range of 1 to 1.1.

In the present invention, the content ratio of the resin composition in the cord is 20 to 50 with respect to 100% by weight of the carbon fiber bundle.
%, Preferably 25 to 45% by weight, more preferably 30 to 40% by weight. If the amount is less than 20% by weight, the fatigue resistance of the cord may decrease due to the rubbing between the single fibers, and if the amount exceeds 50% by weight, the heat resistance, water resistance, solvent resistance, etc. of the cord may decrease. There is.

In the present invention, the content of the rubber latex contained in the resin composition is 100% by weight of the resin composition.
40 to 80% by weight, preferably 45 to 7% by weight.
The content is preferably 5% by weight, more preferably 50 to 70% by weight. If the amount is less than 40% by weight, the flexibility of the cord may be reduced. If the amount is more than 80% by weight, the adhesiveness of the cord may be excessive and the handleability may be deteriorated.

Specific examples of the rubber latex include acrylate-butadiene rubber latex, acrylonitrile-butadiene rubber latex, isoprene rubber latex, urethane rubber latex, chloroprene rubber latex, styrene-butadiene rubber latex, natural rubber latex, and vinylpyridine-styrene. At least one selected from the group consisting of butadiene rubber latex
Seed rubber components. Among them, vinylpyridine-
At least one selected from the group consisting of styrene-butadiene rubber latex, styrene-butadiene rubber latex, and acrylonitrile-butadiene rubber latex is particularly effective for improving the fatigue resistance of the rubber material.

In the present invention, from the viewpoint of improving the fatigue resistance of the rubber material, it is preferable to include an epoxy resin in the resin composition together with the rubber latex.

Specific examples of the epoxy resin include ethylene glycol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol polyglycidyl ether,
At least one selected from the group consisting of hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and neopentyl glycol diglycidyl ether is exemplified. Among them, at least one selected from the group consisting of glycerol polyglycidyl ether, sorbitol polyglycidyl ether, and ethylene glycol diglycidyl ether is effective for improving the fatigue resistance of the rubber material.

The content ratio of the epoxy resin is as follows:
20 to 80% by weight, preferably 30 to 70% by weight, more preferably 40 to 60% by weight with respect to 00% by weight.
It is good. If the amount is less than 20% by weight, the adhesiveness of the cord / rubber interface may decrease. If the amount exceeds 80% by weight, the flexibility of the cord may decrease, and the fatigue resistance may decrease.

In the present invention, an RFL adhesive (a mixture of a resorcinol-formaldehyde resin and a rubber latex) is preferably adhered to the surface of a resin composition layer containing a rubber latex (hereinafter referred to as a rubber latex layer). .

This RFL adhesive is prepared, for example, by adding resorcinol and formalin to an aqueous solution containing an alkaline compound such as sodium hydroxide, and allowing it to stand at room temperature for several hours to allow the initial condensation of resorcinol and formaldehyde.
It can be prepared by a method of adding latex or the like.

The ratio of the RFL adhesive is 10 to 40% by weight, preferably 15 to 35% by weight, more preferably 20 to 30% by weight based on 100% by weight of the resin composition. good. If the amount is less than 10% by weight, the adhesiveness of the cord / rubber interface may be reduced, and may be 80% by weight.
Beyond, the flexibility of the code may decrease.

Further, the rubber latex has a storage elastic modulus (G ′) at 25 ° C. of a dried film formed by a method described below.
The pressure is 0.4 MPa or less, preferably 0.3 MPa or less, and more preferably 0.2 MPa or less.
If it exceeds 0.4 MPa, the flexibility of the cord may be reduced.

The rubber reinforcing cord according to the present invention has a composition as described above, for example, and is JIS L
A fracture life as measured by 1017 of 100 minutes or more;
Preferably it is 110 minutes or more, more preferably 120 minutes or more.

The rubber material according to the present invention is obtained by reinforcing a base material containing rubber with the cord.

Specific examples of the rubber contained in the base material include acrylic rubber, acrylonitrile-butadiene rubber, isoprene rubber, urethane rubber, ethylene-propylene rubber, epichlorohydrin rubber, chlorosulfonated polyethylene rubber, chloroprene rubber, silicone Rubber, styrene-butadiene rubber, polysulfide rubber, natural rubber, butadiene rubber, butyl rubber, fluorine rubber and the like.

In addition to the rubber as the main component, an inorganic filler such as carbon black and silica, an organic filler such as a coumarone resin and a phenol resin, and a softening agent such as a naphthenic oil are added to the base material as required. May be included.

The cord according to the present invention can be manufactured, for example, by the following method. That is, the carbon fiber bundle is passed through a treatment liquid tank containing rubber latex and an epoxy resin, and then a treatment liquid tank containing an RFL adhesive, and then further passed through a heating and drying furnace to remove moisture in the cord. It is.

The rubber material according to the present invention can be produced, for example, by the following method. That is, after the cords arranged in one direction are sandwiched from both sides by a sheet-like base material containing rubber as a main component, the cord / rubber composite is heated and pressed in a press to vulcanize the rubber, It is a molding method.

The rubber material according to the present invention can be suitably used for any of tires, belts and hoses, but is particularly suitable for tires.

In general, a tire is composed of a tread portion and a sidewall portion made of rubber, and a belt portion, a carcass portion and a bead portion made of cord and rubber. And bead portions, and particularly suitable for belt portions.

In the present invention, the carbon fiber bundle or cord is
The evaluation was performed by the following method. <Elongation at break and tensile strength of carbon fiber bundle> JIS R760
Measured according to 1. The tensile test piece was prepared by impregnating a carbon fiber bundle with the following resin composition and heating and curing at 130 ° C. for 35 minutes.

Resin composition: 3,4-ethoxycyclohexylmethyl-3,4-ethoxy-cyclohexane-carboxylate (100 parts by weight) / boron trifluoride monoethylamine (3 parts by weight) / acetone (4 parts by weight) <carbon Cross section shape of a single fiber of the fiber bundle> The carbon fiber bundle is cut by a razor blade from a direction perpendicular to the fiber direction, and the cross section is 10,000 times magnification by a scanning electron microscope.
The photograph was taken under the condition of an acceleration voltage of 15 kV. A circumscribed circle and an inscribed circle are drawn on the photograph of the obtained cross section, and the ratio of the radius R of the circumscribed circle to the radius r of the inscribed circle (= R / r) is used as an index of the cross-sectional deformation degree of the single fiber. . <Initial gradient of stress-strain curve of rubber reinforcing cord> AS
It was measured by the method described in TM D885-76.

The cord to be measured was cut out to a length of 1 m, a metal hook was attached to one end of the cord, a 300 g weight was attached to the other end, and the shape was fixed by hanging for 72 hours.

Next, this cord was cut out to a length of 2 cm to prepare a measurement sample, and this measurement sample was placed at a span interval of 1 cm.
And a metal hook was hung at the center between the spans.

Then, under an environment of a temperature of 25 ° C. and a relative humidity of 40%, the metal hook is lowered at a rate of 2 cm / minute, and the bending load M is defined as the ordinate and the deflection Y is defined as the abscissa.
Curves were drawn. The slope of the tangent of the curve at y = 0 was defined as the initial slope (dM / dy) y = 0. <Number of twists of rubber reinforcing cord> Measured by the method described in JIS R7601.

The distance between both ends of the cord to be measured is 500 m.
m and attached to the clamp of the twisting machine.
Fix one clamp, rotate the other clamp,
Measure the number of revolutions until the twist is completely unwound, and
The multiplied value was defined as the number of twists (times / m) of the cord. <Fatigue resistance of rubber reinforcing cord> Measured according to the method described in JIS L1017.

A rubber sheet having the following composition was wound around a drum, and from above, a cord was wound at an interval of 55/10 cm.
Further, the same rubber sheet was wound thereon. The three-layer laminate of the rubber sheet / cord / rubber sheet thus obtained was removed from the drum, wound around a mandrel, and formed into a tube.

Rubber sheet composition: isoprene rubber (70 parts by weight) / butadiene rubber (30 parts by weight) / sulfur (2 parts by weight) / zinc oxide (5 parts by weight) / stearic acid (2 parts by weight) / diene thiocyanate Sulfite (1 part by weight) / carbon black (60 parts by weight) Next, the rubber was vulcanized by a press at a temperature of 160 ° C., a pressure of 9.8 MPa, and a time of 30 minutes, and molded. Material whose cord orientation matches (outer diameter 27m
m, inner diameter 13 mm, length 24 cm).

Next, the center portion of the rubber material was bent at 90 °, air at a pressure of 0.3 MPa was fed into the tube, and both ends of the tube were cut in the same direction at a temperature of 25 ° C.
Rotated at 50 times / min.

Here, the time required for the tube to break (fracture life) was used as an index of the fatigue resistance of the rubber reinforcing cord. <Storage elastic modulus (G ′) of dried rubber latex film> The stock solution of the measured rubber latex was dried at 140 ° C. for 30 minutes, and the obtained latex film was measured for storage elastic modulus using a viscoelasticity measuring device.

Here, Rheometric Sci is used as a measuring device.
"ARES", a viscoelasticity measurement system expansion type manufactured by entific
And the following method was used.

At a temperature of 25 ° C., a latex film is sandwiched between two circular plates made of aluminum material having a diameter of 16 mm and made to reciprocate by rotating at a frequency of 3.14 rad / sec, and a torque value applied to the circular plate is detected. Was converted to storage modulus.

[0049]

The present invention will be described more specifically with reference to the following examples. (Examples 1 to 8, Comparative Examples 1 to 8) Using the following raw materials, a rubber reinforcing cord and a fiber reinforced rubber material were produced.
Table 1 shows the composition of the resin impregnated in the carbon fiber bundle, and Table 2 shows the results of evaluating the fatigue resistance of the rubber reinforcing cord. 1. Raw materials (1) Carbon fiber bundle (a) "T300B-12K-50B" (model number, manufactured by Toray Industries, Inc.), elongation at break 1.5%, tensile strength 3500 MPa, degree of cross-sectional deformation of single fiber 1.25 (b ) "T700S-12K-50C" (model number, manufactured by Toray Industries, Inc.), elongation at break 2.1%, tensile strength 4900 MPa, cross-sectional deformation of single fiber 1.05 (c) "T800H-12K-40B" ( Model number, manufactured by Toray Industries, Inc.), elongation at break 1.9%, tensile strength 5500 MPa, cross-sectional deformation degree of single fiber 1.37 (2) Rubber latex (a) Vinylpyridine-styrene-butadiene rubber latex: JSR0652 (model number) , Manufactured by JSR Corporation), solid content concentration 40% by weight, storage elastic modulus (G ') 0.11 MPa
(B) Styrene-butadiene rubber latex: JSR2
108 (model number, manufactured by JSR Corporation), solid content concentration 40% by weight, storage elastic modulus (G ') 0.11 MPa (25 ° C.) (c) Acrylonitrile-butadiene rubber latex: “Nippol” LX513 (registered trademark, Japan) ZEON CORPORATION), solid content concentration 45% by weight, storage modulus (G ')
0.47 MPa (25 ° C.) (d) Butadiene rubber latex: “Nippol” LX
111F (registered trademark, manufactured by Zeon Corporation), solid content concentration 55% by weight, storage elastic modulus (G ') 0.46 MPa (25
(C) (3) Epoxy resin (a) Ethylene glycol diglycidyl ether: "Epolite" 40E (registered trademark, manufactured by Kyoeisha Chemical Co., Ltd.)
1. Epoxy equivalent 130 (b) polyethylene glycol diglycidyl ether: "Epolite" 400E (registered trademark, manufactured by Kyoeisha Chemical Co., Ltd.), epoxy equivalent 290 Production / Evaluation After transporting the carbon fiber bundle at 10 m / min and passing it through a processing liquid tank containing rubber latex and epoxy resin, and then a processing liquid tank containing RFL adhesive, a heating and drying oven at 150 ° C. was further applied. To remove the water contained in the treatment liquid to obtain a rubber reinforcing cord.

Here, the composition of the resin after drying was as shown in Table 1. The content ratio of the resin composition was as follows.
It was 30% by weight relative to 0% by weight.

The initial gradient (dM / dy) y = 0 of the bending load M-deflection Y curve of the obtained cord was measured by the method described above.

Next, a tube-shaped material was manufactured according to the above-described method, and the breaking life was measured.

As shown in Table 2, the rubber reinforcing cord according to the present invention was excellent in fatigue resistance.

[0054]

[Table 1]

[0055]

[Table 2]

(Examples 9 to 16, Comparative Examples 9 to 16) Using the following raw materials, a rubber reinforcing cord and a fiber reinforced rubber material were produced.

Tables 3 and 4 show the composition of the resin impregnated in the carbon fiber bundle, and Table 5 shows the evaluation results of the fatigue resistance of the rubber reinforcing cord. 1. Raw materials (1) Carbon fiber bundle (a) "T300-12K-50B" (model number, manufactured by Toray Industries, Inc.), elongation at break 1.5%, tensile strength 3500 MPa, degree of cross-sectional deformation of single fiber 1.25 (b ) "T700S-12K-50C" (model number, manufactured by Toray Industries, Inc.), elongation at break 2.1%, tensile strength 4900 MPa, cross-sectional deformation of single fiber 1.05 (c) "T800H-12K-40B" ( (Model number, manufactured by Toray Industries, Inc.), elongation at break: 1.9%, tensile strength: 5,500 MPa, cross-sectional deformation of single fiber 1.37 (2) Rubber latex (a) Vinylpyridine-styrene-butadiene rubber latex: "Nippol" 2518FS (registered trademark, manufactured by Zeon Corporation), solid content concentration: 40.5% by weight, storage modulus (G '): 0.11 MPa (25 ° C.) (b) Styrene-butadiene rubber latex: “Nippol” LX110 ( Registered trademark, manufactured by Nippon Zeon Co., Ltd.), solid content concentration 40.5% by weight, storage modulus (G ') 0.11MP
a (25 ° C.) (3) epoxy resin (a) glycerol polyglycidyl ether: “Denacol” EX-313 (registered trademark, manufactured by Nagase Kasei Kogyo Co., Ltd.),
Epoxy equivalent 141 (b) Sorbitol polyglycidyl ether: "Denacol" EX-614 (registered trademark, manufactured by Nagase Kasei Kogyo Co., Ltd.),
Epoxy equivalent 167 2. Production / Evaluation A carbon fiber bundle was transported at 10 m / min, passed through a treatment liquid tank containing a rubber latex / epoxy resin having a composition shown in Table 3, and then treated with an RFL adhesive having a composition shown in Table 4. The liquid was passed through the tank.

Next, the mixture was passed through a heating and drying oven at 150 ° C. to remove the water contained in the treatment liquid, thereby obtaining a rubber reinforcing cord.

Here, the content ratio of the dried rubber latex / epoxy resin and the content ratio of the RFL adhesive were 20% by weight and 5% by weight, respectively, based on 100% by weight of the carbon fiber bundle.

Further, while rotating the bobbin on which the cord was wound, the cord was unwound at a rate of 5 m / min to give a predetermined number of twists.

Next, a tube-shaped material was manufactured according to the above-described method, and the breaking life was measured.

As shown in Table 5, the rubber reinforcing cord according to the present invention was excellent in fatigue resistance.

[0063]

[Table 3]

[0064]

[Table 4]

[0065]

[Table 5]

[0066]

According to the rubber reinforcing cord of the present invention, it is possible to obtain a fiber reinforced rubber material which exhibits excellent fatigue resistance and practicality, which is preferably used particularly for a tire cord while using carbon fibers. .

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Claims (15)

[Claims] 1. A substantially non-twisted rubber reinforcing cord comprising a carbon fiber bundle having a breaking elongation of 1.7% or more. 2. The rubber reinforcing cord according to claim 1, wherein the carbon fiber bundle is impregnated with a resin composition containing rubber latex. 3. A carbon fiber bundle having a breaking elongation of 1.7% or more,
A rubber reinforcing cord impregnated with a resin composition containing rubber latex, wherein the initial gradient (dM / d) of a bending load M-deflection y curve according to ASTM D885-76.
y) A rubber reinforcing cord in which y = 0 is 1000 N / m or less. 4. A carbon fiber bundle having a breaking elongation of 1.7% or more,
A rubber reinforcing cord impregnated with a resin composition containing rubber latex, wherein the number of twists according to JIS R7601 is 10 turns / m or less. 5. The tensile strength of the carbon fiber bundle is 4000MP.
The rubber reinforcing cord according to any one of claims 1 to 4, which is at least a. 6. The number of single fibers constituting the carbon fiber bundle is as follows:
The rubber reinforcing cord according to any one of claims 1 to 5, wherein the number is 4000 to 20,000. 7. The rubber reinforcing cord according to claim 1, wherein the cross-sectional shape of the single fiber constituting the carbon fiber bundle is substantially a perfect circle. 8. The rubber reinforcing cord according to claim 2, wherein a content ratio of the resin composition to 100% by weight of the carbon fiber bundle is 20 to 50% by weight. 9. The rubber reinforcing cord according to claim 1, wherein a content ratio of the rubber latex to 100% by weight of the resin composition is 40 to 80% by weight. 10. The rubber latex according to claim 10, wherein the acrylate is
At least one selected from the group consisting of butadiene rubber latex, acrylonitrile-butadiene rubber latex, isoprene rubber latex, urethane rubber latex, chloroprene rubber latex, styrene-butadiene rubber latex, natural rubber latex, and vinylpyridine-styrene-butadiene rubber latex The rubber reinforcing cord according to any one of claims 1 to 9, comprising the rubber component of (1). 11. The resin composition according to claim 1, wherein the ethylene glycol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol polyglycidyl ether, hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl. The rubber reinforcing cord according to any one of claims 1 to 10, comprising at least one epoxy resin selected from the group consisting of ether and neopentyl glycol diglycidyl ether. 12. The rubber reinforcing cord according to claim 2, wherein an RFL adhesive is adhered to the surface of the rubber latex layer. 13. The film obtained by drying the rubber latex has a storage elastic modulus (G ′) at 25 ° C. of 0.4 MPa.
The rubber reinforcing cord according to any one of claims 2 to 12, which is equal to or less than a. 14. A rubber reinforcing cord comprising a carbon fiber bundle having a breaking elongation of 1.7% or more impregnated with a resin composition containing rubber latex, and having a breaking life of 100 measured according to JIS L1017. Rubber reinforcement cord that is more than a minute. 15. A fiber-reinforced rubber material comprising a rubber-containing base material reinforced by the rubber reinforcing cord according to any one of claims 1 to 14.