JP2003301334A - Rubber-reinforcing carbon fiber bundle, rubber- reinforcing cord and fiber-reinforced rubber material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber-reinforcing carbon fiber bundle excellent in adhesiveness of the carbon fiber with a rubber compound and fatigue resistance to flex deformation, a rubber-reinforcing cord and a fiber reinforced rubber material. <P>SOLUTION: The rubber-reinforcing carbon fiber bundle begins to sediment within 20 seconds when a piece of the carbon fiber bundle cut in 20 mm length is floated on a water surface and has ≥500 MPa knot strength. The rubber- reinforcing cord contains 20-80 pts.wt. resin composition based on 100 pts.wt. rubber-reinforcing carbon fiber bundle. The fiber reinforced rubber material is a rubber-containing base material reinforced with the rubber-reinforcing cord. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber bundle for rubber reinforcement, a rubber reinforcement cord and a fiber reinforced rubber material which are excellent in adhesiveness between carbon fibers and a rubber compound and fatigue resistance. More specifically, it relates to a rubber-reinforcing carbon fiber bundle that can be suitably used as a reinforcing material for various rubber materials such as tires, belts and hoses.

[0002]

2. Description of the Related Art Industrial rubber products such as tires, belts and hoses are usually composites reinforced with fiber materials, and strong adhesion is required between fibers and rubber. Conventionally, as a method of adhering fibers to rubber, it is preferable to treat fibers in advance with a resorcin / formalin / rubber latex mixed liquid (hereinafter referred to as RFL liquid) and then to adhere and vulcanize it with unvulcanized rubber. Are known.

The fiber material is required to have excellent properties such as tensile strength, tensile elastic modulus, heat resistance, water resistance, and fatigue resistance. Above all, in order to endure deformation by external force, fatigue resistance, Fiber / rubber adhesion is important.

Carbon fiber has good tensile modulus, tensile strength, heat resistance and water resistance, and a fiber reinforced rubber material using the same has excellent dimensional stability and weather resistance. However, there is a problem that the carbon fiber cord is apt to be broken due to the rubbing of the single fibers and peeling is likely to occur at the interface between the carbon fiber cord and the rubber, resulting in poor fatigue resistance. In particular, in applications that are used for a long time in a humid high temperature environment, such as power transmission belts used in automobile engine rooms, durability is required to guarantee water resistance and heat resistance under stress conditions for a long time. However, there is a problem that the fatigue resistance and the fiber / rubber adhesion in such a severe environment are not sufficient.

JP-A-52-56181 and JP-A-60-181369 disclose methods of impregnating carbon fiber bundles with a resin composition prepared by mixing an RFL solution with an epoxy resin. Further, Japanese Patent No. 1912103 discloses a method for activating a fiber with a specific active compound, and Japanese Patent No. 1510424 includes a specific acrylate compound after a carbon fiber is treated with a polyurethane resin solution. A method of treating with rubber glue is disclosed. Further, in Japanese Patent Laid-Open No. 2000-309655, 7
A method of impregnating carbon fiber with a liquid rubber having a viscosity at 0 ° C. in a specific range is disclosed, and JP-A-2001-23
Japanese Patent No. 4445 discloses a method of obtaining a cord having flexibility in a specific range by impregnating carbon fibers having a breaking elongation of 1.7% or more with a resin composition containing rubber latex.

However, even by these methods,
Durability with no practical problems as a carbon fiber reinforced rubber material,
In particular, there is no one having flexural fatigue resistance and fiber / rubber adhesiveness under a humid heat environment, and at present, a sufficiently satisfactory carbon fiber cord for rubber reinforcement has not been obtained.

[0007]

In view of such background of the prior art, the present invention has excellent adhesiveness between carbon fiber and a rubber compound in a wet high temperature environment, and also has fatigue resistance against bending deformation. An excellent carbon fiber bundle for rubber reinforcement and a rubber reinforcement cord are provided.

[0008]

The present invention employs the following means in order to solve the above problems. That is, when a small piece of carbon fiber bundle cut into a length of 20 mm is floated on the water surface, it begins to settle into water within 20 seconds, and the knot strength of the carbon fiber bundle is 500 MPa or more, for rubber reinforcement. It is a carbon fiber bundle. Further, the present invention provides a rubber-reinforcing cord comprising 20 to 80 parts by weight of a resin composition containing rubber with respect to 100 parts by weight of the carbon fiber bundle, and the rubber-reinforcing cord contains rubber. The present invention provides a fiber-reinforced rubber material, characterized in that the base material is reinforced.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a rubber having the above-mentioned problems, that is, excellent adhesiveness between a carbon fiber and a rubber compound, and also excellent fatigue resistance to bending deformation (hereinafter, simply referred to as fatigue resistance). Surprisingly, in order to obtain a reinforcing carbon fiber bundle, the settling start time when a small piece of the carbon fiber bundle is floated on the water surface is within a certain value, and the knot strength of the carbon fiber is set to a certain value or more. However, they have found that such problems can be solved at once.

The carbon fiber bundle used in the present invention is 20
When cut to a length of mm and floated on the water surface, it is necessary to start sedimentation in water within 20 seconds. If it exceeds 20 seconds, the adhesive strength with the rubber decreases, especially when exposed to a humid environment for a long period of time. Also, fatigue resistance is not preferable. More preferably, it is within 15 seconds, and particularly preferably 10
It is to start sinking within seconds.

By using the above-mentioned carbon fiber bundle, the impregnation property of the resin liquid into the carbon fiber bundle is improved,
It is considered that the rubbing of single fibers inside the carbon fiber bundle can be effectively suppressed, and the potential of the high knot strength carbon fiber can be fully utilized. Further, since the wettability with the resin liquid is good, it is presumed that the adhesive strength is maintained even in a wet and high temperature environment.

The carbon fiber bundle used in the present invention must have a knot strength of 500 MPa or more,
Preferably 600 MPa or more, more preferably 700 M
It is preferably Pa or more. If it is less than 500 MPa, the fatigue resistance tends to be insufficient, and it may not be used in applications such as tires and belts. Especially, the knot strength is 75
0 MPa is often sufficient for achieving the effects of the present invention.

The reason why the fiber-reinforced rubber material according to the present invention is excellent in fatigue resistance despite the fact that carbon fibers are used as the reinforcing fibers is that a carbon fiber bundle having a knot strength of a specific value or more as described above is used. Due to the combination of use and protection of the monofilaments by the soft resin containing rubber. It is presumed that the mechanism is due to the synergistically suppressing frictional damage between the single fibers, but wetting with the liquid such as the resin liquid as described above in order to promote the resin impregnation inside the fiber bundle. It is necessary to use a carbon fiber bundle having good properties.

The carbon fiber bundle of the present invention has a solubility parameter (SP value) of 8.0 to 12.0 (ca) on its surface.
l) A sizing agent in the range of ^1/2 / (cm) ^3/2 is preferably added. If the SP value is less than 8.0, the adhesiveness with the rubber compound may not be sufficiently obtained. If the SP value exceeds 12.0, the single fibers are likely to aggregate with each other, and sufficient fatigue resistance may not be obtained.

Here, the solubility parameter (SP value) is an index of compatibility, and Polym. Eng. Sc
i. , 14 (2), 147-154 (1974), and the molecular structure is determined by the method of Fedors.

The amount of the sizing agent attached to the carbon fiber bundle is 100% by weight of the carbon fiber bundle before sizing.
, Preferably in the range of 0.1 to 1.5% by weight,
More preferably, it is in the range of 0.3 to 1.3% by weight. If it is less than 0.1% by weight, sufficient adhesion to the rubber compound may not be obtained. If it exceeds 1.5% by weight, the rubber-reinforcing cord becomes hard and fatigue resistance may deteriorate.

The sizing agent may be applied to the carbon fiber bundle by, for example, passing the carbon fiber through a sizing solution in which the sizing agent is dissolved or dispersed so that the sizing agent is attached to the surface of the carbon fiber and then heated to remove the solvent. There is a method of removing.

In the present invention, the solubility parameter (SP
Any sizing agent having a value of 8.0 to 12.0 can be used, but a compound having an epoxy group is preferably used.

The compound having an epoxy group which can be preferably used for sizing in the present invention is preferably a compound having two or more epoxy groups in the molecule, for example, bisphenol A type epoxy resin and bisphenol F.
Type epoxy resin, bisphenol AD type epoxy resin and the like can be used. A modifier may be added to such an epoxy resin depending on the application.

As a method of applying the compound having an epoxy group to the carbon fiber bundle, a method of passing through an aqueous emulsion storage tank of the compound having an epoxy group, followed by heating and drying is used.

As the form of the carbon fibers, carbon fibers obtained by twisting and firing precursor fibers, so-called twisted yarns, carbon fibers obtained by untwisting the twisted yarns, so-called untwisted yarns, precursor fibers are substantially formed. Although a non-twisted yarn that is heat-treated without twisting can be used, a non-twisted yarn or an untwisted yarn is preferable in consideration of the balance between resin impregnability and strength characteristics,
Furthermore, the non-twisted yarn is preferable in that the resin is easily impregnated to the central portion of the carbon fiber bundle.

The carbon fiber bundle of the present invention has a fineness of 2000 to 10000 dtex, more preferably 300.
0 to 9000 dtex, particularly preferably 4000 to 80
It is good that it is 00 dtex. If it is less than 2000 dtex, the reinforcing effect of the rubber material may be insufficient.
If it exceeds 000 dtex, the cord may not be sufficiently impregnated with the resin composition, and the fatigue resistance of the rubber-reinforcing cord may deteriorate.

Further, the tensile strength of the carbon fiber bundle is preferably 4000 MPa or more, more preferably 4400 MPa or more, particularly preferably 4800 MPa.
The above is good. If the pressure is less than 4000 MPa, the cord is likely to break when the rubber material is subjected to excessive stress, and it may not be used in applications such as tires and belts that require high fatigue resistance.

In the carbon fiber bundle according to the present invention, it is preferable that the cross-sectional shape of the single fiber constituting the carbon fiber bundle is substantially a perfect circle. The cross-sectional shape of the single fiber is other than that, for example,
If the shape is elliptical, lentil-shaped, or trefoil-shaped, the friction between the single fibers increases, and the fatigue resistance may decrease.

Here, "substantially a perfect circle" means
Ratio (= R of circumscribed circle radius R and inscribed circle radius r of single fiber cross section)
The cross-sectional deformation degree defined by / r) is within the range of 1.0 to 1.1.

The surface of the carbon fiber bundle for rubber reinforcement of the present invention can be modified by some treatment. As a means for modifying the surface of the carbon fiber, a method of electrolytically treating the surface of the fiber is preferably adopted. For example, a method of electrolytically treating the surface of the fiber bundle with alkali is preferably used.

Specific examples of the electrolyte dissolved in the alkaline electrolyte in the electrolytic treatment means include hydroxides such as sodium hydroxide and potassium hydroxide, inorganic salts such as ammonia, sodium carbonate and sodium hydrogen carbonate, and sodium acetate. , Organic salts such as sodium benzoate, potassium salts thereof, barium salts or other metal salts, and organic compounds such as ammonium salts, tetraethylammonium hydroxide or hydrazine are preferably used, but they do not hinder the curing of the resin. From the perspective of losing
Those containing no alkali metal, that is, ammonium carbonate, ammonium hydrogencarbonate, and tetraalkylammonium hydroxides are more preferably used.

When it is desired to employ the method of electrolytic treatment with acid, it is preferable to use an inorganic acid such as sulfuric acid or nitric acid, an organic acid such as acetic acid or butyric acid, or a salt such as ammonium sulfate or ammonium hydrogensulfate as the electrolyte. it can.

In the electrolytic treatment, the amount of electricity to be applied can be optimized according to the carbonization degree of the carbon fiber. That is, the amount of electricity is preferably in the range of 3 to 500 coulombs / g (g: weight of carbon fiber), and more preferably 5 to 200 coulombs / g in order to moderately decrease the crystallinity of the surface layer. It is preferably adopted from the viewpoint of suppressing.

After the electrolytic treatment, the yarn is preferably washed with water and dried. In the drying, if the temperature is too high, the functional groups existing on the outermost surface of the carbon fiber are likely to disappear by thermal decomposition. Therefore, it is desirable to keep the drying temperature as low as possible, preferably 250 ° C. or lower, and more preferably 220 ° C.
It is better to dry below ℃.

Further, the present invention is a rubber-reinforcing cord containing 20 to 80 parts by weight of a resin composition with respect to 100 parts by weight of such a carbon fiber bundle. That is, the above-mentioned carbon fiber bundle is impregnated with the resin composition, and the resin is present on the entire surface of the fiber bundle to form a cord-shaped material.

If the carbon fiber bundle is not impregnated with the resin composition, the cord often breaks due to friction between the single fibers when subjected to stress deformation such as bending deformation. If the resin is not attached to the surface of the cord, the cord may peel off at the interface with the rubber as the adherend. If the resin content is less than 20 parts by weight, the fatigue resistance of the cord will be reduced due to the rubbing of the single fibers, and the surface resin will be insufficient and the adhesiveness to the rubber will also be reduced. On the contrary, when the content of the resin composition exceeds 80 parts by weight, the cord tends to be too rigid, and buckling due to bending deformation is likely to occur, resulting in deterioration of fatigue resistance. In addition, heat resistance and water resistance may decrease, and adhesion in a wet high temperature environment may decrease.

The resin composition used for the rubber-reinforcing cord of the present invention preferably contains 20 to 80% by weight of a rubber component after drying with respect to 100% by weight of the resin composition. If it is less than 20% by weight, when subjected to stress deformation such as bending deformation, the cord may be broken due to rubbing of the single fibers, or peeling from the cord may occur at the rubber interface. On the other hand, if it exceeds 80% by weight, the adhesiveness of the cord becomes excessive and the handleability may deteriorate.

Rubber latex is preferably used as the rubber component. By using the rubber latex, the viscosity of the entire resin composition is lowered, the inside of the carbon fiber bundle is easily impregnated with the resin, and the role of protecting the single fiber with the resin is facilitated.

The rubber latex is generally one in which a polymer is stably dispersed in water, and after impregnating a carbon fiber bundle with a resin composition, water remaining in the cord is removed by heating and drying. It is preferable to keep it. If water remains in the cord, it may cause voids that impair the fatigue resistance of the cord. The temperature for heating and drying is 10
The range of 0-270 degreeC is preferable, and the range of 150-240 degreeC is more preferable.

As the rubber latex, butadiene rubber latex, acrylonitrile-butadiene rubber latex, isoprene rubber latex, urethane rubber latex, chloroprene rubber latex, styrene-butadiene rubber latex, natural rubber latex, vinylpyridine-styrene-butadiene rubber latex, etc. Can be used. Among them, acrylonitrile-butadiene rubber latex and vinylpyridine-styrene-butadiene rubber latex are particularly effective in improving fatigue resistance,
It is preferably used.

In the present invention, it is preferable to mix an epoxy resin into the resin composition in order to further improve the fatigue resistance of the cord.

As the epoxy resin, glycerol polyglycidyl ether, sorbitol polyglycidyl ether, trimethylolpropane polyglycidyl ether, hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether and the like can be used. Among them, glycerol polyglycidyl ether and sorbitol polyglycidyl ether are particularly effective in improving fatigue resistance and are preferably used.

The epoxy resin is 100% by weight of the resin composition.
Medium, after drying, 20 to 80% by weight, preferably 30 to 70
It is preferable that the content is 40% by weight, more preferably 40 to 60% by weight. If it is less than 20% by weight, the adhesion to the cord at the rubber interface may be insufficient, and if it exceeds 80% by weight, the flexibility of the cord may be lowered and fatigue resistance may be insufficient.

In the present invention, in order to further improve the adhesiveness of the cord / rubber, it is preferable to attach resorcin-formalin rubber latex (hereinafter, RFL) to the cord surface.

Here, "adhering to the surface of the cord" means that 90% or more of the total RFL is unevenly distributed within the area of the outer peripheral portion corresponding to 10% of the total cross-sectional area of the cord.

The uneven distribution of RFL at the cord / rubber interface further enhances the adhesiveness at the cord / rubber interface.

The method of unevenly distributing RFL on the surface of the rubber-reinforcing cord is not particularly limited, but the carbon-fiber bundle is impregnated with a resin composition to form a cord-shaped material. It is also possible to adopt a method of giving.

For example, it can be manufactured by the following method. That is, after passing the carbon fiber bundle through the treatment liquid tank made of the resin composition, heat drying, then,
This is a method in which the water in the cord is removed by passing it through a treatment liquid tank containing RFL and then through a heating and drying furnace.

All RFLs included in the rubber reinforcing cord
The content ratio of is preferably 1 to 20 parts by weight, and more preferably 2-1 to 100 parts by weight of the carbon fiber bundle after drying.
5 parts by weight, particularly preferably 3 to 10 parts by weight. If it is less than 1 part by weight, the adhesiveness at the cord / rubber interface may be reduced, and if it exceeds 20 parts by weight, the flexibility of the cord may be reduced and it may adhere to the roll (gum-up) in the cord production process. May occur and the quality stability may be impaired.

The manufacturing method of RFL is not particularly limited,
It can be prepared using an initial condensation product of resorcin and formalin. Particularly, RFL can be preferably prepared using a resorcin-formalin initial condensation product obtained by initial condensation under an alkali catalyst. For example,
Resorcinol and formalin are added and mixed in an alkaline aqueous solution containing an alkaline compound such as sodium hydroxide, and the mixture is allowed to stand at room temperature for several hours to initially condense resorcinol and formaldehyde, and then rubber latex is added to form a mixed emulsion. Adjusted by the method.

The resorcin-formalin initial condensate preferably has a molar ratio of resorcin to formalin of 1: 0.3.
˜1: 5, more preferably 1: 0.75 to 1: 2.0
The thing of the range of can be used. If it deviates from this range, the adhesion between the rubber and the fiber may become insufficient.

As the rubber latex used for the preparation of RFL, acrylonitrile-butadiene rubber latex, isoprene rubber latex, urethane rubber latex, chloroprene rubber latex, styrene-butadiene rubber latex, vinylpyridine-styrene-butadiene rubber latex, hydrogenated nitrile rubber latex. And synthetic rubber latex. Of these, vinyl pyridine-styrene-butadiene rubber latex is
It is particularly effective in improving fatigue resistance and is preferably used.

The compounding ratio of the resorcinol formalin initial condensate and the rubber latex in RFL is in the range of 1: 3 to 1: 8, preferably 1: 4 to 1: 6 in terms of solid content weight ratio. If it is out of this range, the adhesiveness may be insufficient.

The resin composition treatment liquid used for the rubber-reinforcing cord of the present invention can be adjusted in concentration by adding water in order to enhance the impregnation property into the carbon fiber bundle. Here, it is preferable to use ion-exchanged water as the water from the viewpoint of improving the stability of the treatment liquid. The concentration of the resin composition treatment liquid is preferably 20 to 80% by weight, more preferably 30 to 7% by weight.
It is preferably 0% by weight. If it is less than 20% by weight, impregnation of the resin inside the carbon fiber bundle becomes insufficient,
Fatigue resistance may deteriorate. If it exceeds 80% by weight, the storage stability of the treatment liquid may be deteriorated, and the solid content may be agglomerated or settled, so that the dipping treatment may be impossible. Here, the concentration of the resin composition treatment liquid is a value obtained by dividing the weight of the dried solid substance contained in the resin composition treatment liquid by the weight of the resin composition treatment liquid before drying.

In the present invention, the treatment of the carbon fiber bundle with the resin composition is carried out by immersing the carbon fiber bundle in the resin composition,
It is performed by heat treatment. This heat treatment fixes the resin liquid impregnated or adhered to the carbon fiber bundle,
It may be carried out at a temperature sufficient to remove water, usually 10
It may be processed at 0 to 270 ° C for several minutes.

Further, it is preferable to add a solvent such as water to the above-mentioned RFL and use it as an RFL liquid from the viewpoint of uniformly applying it on the carbon fiber bundle. As the water, it is preferable to use ion-exchanged water from the viewpoint of improving the stability of the RFL solution. The concentration of the RFL liquid is preferably 10 to 40% by weight, more preferably 15 to 30% by weight. 10
If it is less than wt%, the amount of RFL adhered becomes insufficient,
The adhesive strength may be insufficient. The concentration of RFL solution is 4
If it exceeds 0% by weight, the storage stability of the RFL solution may be deteriorated, and the solid content may agglomerate to reduce the concentration or the like, which makes it difficult to uniformly attach the RFL. Here, the concentration of the RFL liquid is a value obtained by dividing the weight of the dried solid substance contained in the RFL liquid by the weight of the RFL liquid before drying.

The rubber-reinforcing cord of the present invention is preferably twisted. The twist number is 100 times / m or less, preferably 10 times / m to 80 times / m, and more preferably 20 times / m to 60 times / m. 100 times / m
If it exceeds, kink is likely to occur, which may lead to deterioration of strength and deterioration of operability. In addition, the twist is given
Although any step may be performed before or after the impregnation of the resin composition, in order to promote the impregnation of the resin composition into the carbon fiber bundle, it is more preferable to impart the twist after impregnating the resin composition in the opened state.

The twisted structure may be a single twisted structure in which one cord is twisted, and a so-called twisted structure is first made by first twisting a few cords, and then adding several twisted cords together to add an upper twist. It may have a twisted structure.

The rubber-reinforcing cord treated as described above is brought into close contact with a base material containing rubber, and vulcanized and adhered under normal processing conditions known for the base material containing rubber. Therefore, it becomes possible to achieve strong adhesion between the carbon fiber and the base material containing rubber.

The fiber-reinforced rubber material of the present invention comprises a base material containing rubber reinforced by the cord.

Here, the rubber content is 50 to 100% by weight of the base material.
It is preferably contained in 100% by weight.

Specific examples of the rubber contained in the base material include acrylic rubber, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, isoprene rubber, urethane rubber, ethylene-propylene rubber, epichlorohydrin rubber and chlorosulfonated rubber. Polyethylene rubber, chloroprene rubber, silicone rubber, styrene-butadiene rubber, polysulfide rubber, natural rubber, butadiene rubber, butyl rubber, fluororubber and the like can be used.

In addition to rubber which is the main component, the base material includes an inorganic filler such as carbon black and silica, an organic filler such as coumarone resin and phenol resin, a softening agent such as naphthenic oil and an antiaging agent. A vulcanization aid, a processing aid and the like may be included as necessary.

The fiber-reinforced rubber material of the present invention can be manufactured, for example, by the following method. That is, the cords aligned in one direction are sandwiched from both sides by a sheet-like base material containing rubber as a main component, and then the cord / rubber composite is heated / pressurized in a press machine to vulcanize the rubber,
It is a molding method.

The rubber material according to the present invention can be suitably used for tires, belts and hoses. In the case of tires, natural rubber and styrene-butadiene rubber are particularly suitable. For power transmission belts, the use of hydrogenated acrylonitrile-butadiene rubber is particularly suitable.

Depending on the type of rubber used for such a base material, it is preferable to include the same type of rubber component in the resin composition used for the above-mentioned rubber-reinforcing cord, as a fiber-reinforced rubber material having good adhesion and bending resistance. It is preferable for obtaining fatigue resistance.

[0063]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

In the present example, in producing the cord, the following carbon fiber bundle, rubber latex,
And epoxy resin was used. <Raw material> (Carbon fiber bundle) -Carbon fiber A: Knot strength 790 MPa, Tensile strength 480
0 MPa, fineness 8100 dtex, cross-sectional deformation of single fiber 1.04, SP value of sizing agent 11.5 (cal)
^1/2 / (cm) ^3/2 , 0.5% by weight of sizing agent,
Settling start time of 20 mm long carbon fiber bundle pieces 8.0
Second, untwisted yarn / carbon fiber B: knot strength 780 MPa, tensile strength 480
0 MPa, fineness 81,000 dtex, cross-sectional deformation of single fiber 1.04, SP value of sizing agent 11.3 (cal)
^1/2 / (cm) ^3/2 , 0.5% by weight of sizing agent,
Sedimentation start time of carbon fiber bundle pieces of 20 mm length 12.2
Second, untwisted yarn / carbon fiber C: knot strength 780 MPa, tensile strength 480
0 MPa, fineness 8100 dtex, cross-sectional deformation of single fiber 1.04, SP value of sizing agent 10.3 (cal)
^1/2 / (cm) ^3/2 , 0.5% by weight of sizing agent,
Sedimentation start time of carbon fiber bundle small pieces of 20 mm length 45.0
Second, untwisted yarn / carbon fiber D: knot strength 310 MPa, tensile strength 480
0 MPa, fineness 8100 dtex, cross-sectional deformation of single fiber 1.04, SP value of sizing agent 11.3 (cal)
^1/2 / (cm) ^3/2 , 0.5% by weight of sizing agent,
Settling start time for carbon fiber bundle pieces 20 mm long 7.9
Second, untwisted yarn / carbon fiber E: knot strength 770 MPa, tensile strength 480
0 MPa, fineness 8100 dtex, cross-sectional deformation of single fiber 1.04, SP value of sizing agent 7.3 (cal) ^1/2
/ (Cm) ^3/2 , 0.5% by weight of sizing agent, 2
Settling start time of 0 mm long carbon fiber bundle pieces is 8.1 seconds,
Untwisted yarn / carbon fiber F: Knot strength 790 MPa, Tensile strength 480
0 MPa, fineness 8100 dtex, cross-sectional deformation of single fiber 1.04, SP value of sizing agent 11.5 (cal)
^1/2 / (cm) ^3/2 , 2.5% by weight of sizing agent,
Settling start time of 20 mm long carbon fiber bundle pieces 8.3
Second, non-twisted yarn (rubber latex) Vinyl pyridine-styrene-butadiene rubber latex: Pilatex (registered trademark) FS (Japan A & L Co., Ltd.)
Styrene-butadiene rubber latex: Nipol (registered trademark) LX110 (manufactured by Zeon Corporation), solid concentration 40.5% (epoxy resin) -glycerol polyglycidyl ether: denacol (Registered trademark) EX-313 (manufactured by Nagase Kasei Co., Ltd.)-Sorbitol polyglycidyl ether: Denacol E
X-614 (manufactured by Nagase Kasei Co., Ltd.) Further, the evaluation method of the carbon fiber bundle used in this example is as follows. <Settling start time of small pieces of carbon fiber bundle> Length of carbon fiber is 1 m
Cut it out and tie a metal hook to one end,
A 300 g weight was tied to the other end, suspended in the air for 72 hours, allowed to stand vertically, and the fiber was cut to a length of 20 mm to obtain a measurement sample without curl. 300 ml of ion-exchanged water was put into a 500 ml beaker, and the measurement sample was floated on the water surface. The time until a part of the sample started to settle was visually determined, and this was repeated 10 times, and the average value was used as the settling start time of the carbon fiber bundle pieces. <Knot strength of carbon fiber bundle> JIS L1013-198
A knot was formed in the center between the grips of the sample according to 1, and the tensile strength was measured.

In this example, both ends of the carbon fiber bundle to be measured were sandwiched and fixed by a chuck. Here, the sample length between the chucks was 250 mm, and the knot of the carbon fiber bundle was positioned in the central portion between the chucks.

Next, in an environment of temperature 25 ° C. and humidity 40%,
The carbon fiber bundle was pulled at a speed of 50 mm / min and the maximum load value was measured.

Next, the value obtained by dividing the maximum load value by the cross-sectional area of the carbon fiber bundle (= basis weight of the carbon fiber bundle / density of the carbon fiber bundle) was taken as the knot strength.

Here, n = 10 for arbitrarily selected carbon fiber bundles (n = 5 for right knot and left knot)
The average value of was used as the nodule strength value. <Tensile strength of carbon fiber bundle> Measured according to JIS R7601. The tensile test piece was prepared by impregnating a carbon fiber bundle with the following resin composition and heat-curing the same at 130 ° C. for 35 minutes.

Resin composition: 3,4-epoxycyclohexylmethyl-3,4-epoxy-cyclohexane-carboxylate (100 parts by weight) / 3 boron trifluoride monoethylamine (3 parts by weight) / acetone (4 parts by weight) Cross-sectional shape of fiber> Single-fiber cross-sectional shape was obtained by observing the cross-section of the single fiber with a scanning electron microscope.

In this example, the carbon fiber to be measured was cut with a razor from the direction perpendicular to the fiber axis, and its cross section was observed with a scanning electron microscope at a magnification of 10,000 times and an acceleration voltage of 15 kV.
Photographed under the conditions.

The circumscribed circle and the inscribed circle are drawn on the obtained cross-section photograph, and the ratio (= R / r) of the radius (R) of the circumscribed circle and the radius (r) of the inscribed circle is calculated. Degree of deformation. In addition, the average value of n = 5 was made into the cross-section deformation degree about the carbon fiber bundle selected arbitrarily here. <Cord production / evaluation> (1) Resin impregnation (cord production) A carbon fiber bundle was conveyed at a speed of 10 m / min, passed through a treatment liquid tank (first bath) containing a resin composition, and heated at 170 ° C. Water was removed by passing through the furnace. The obtained product was twisted in a predetermined twist by a twisting machine, and then passed through a treatment liquid tank (second bath) containing an RFL liquid. Furthermore, it is passed through a heating furnace at 170 ° C. to remove water contained in the treatment liquid,
A rubber reinforcing cord was obtained. It should be noted that the amount of resin adhering to the first bath of the dried code and the amount of adhering RFL of the second bath are as follows.
For 0 parts by weight, 30 parts by weight and 5 parts by weight, respectively, were used as a standard.

In this example, the resin composition having the composition shown in Table 1 or 2 was used as the treatment liquid for the first bath, and R shown in Table 3 was used.
The FL solution was used as the treatment solution for the second bath. (2) Evaluation of fiber unit weight / resin unit weight The fiber fineness and the amount of resin adhesion are measured in advance by measuring the weight of the carbon fiber bundle per unit length (that is, the basis weight of the carbon fiber bundle), and then measuring the same length after resin impregnation. By measuring the cord weight (that is, the basis weight of the carbon fiber cord), the resin basis weight as a difference and the weight part were calculated. (2) Evaluation of twist number of rubber-reinforcing cord It was measured by the method described in JIS R7601. Both ends of the cord to be measured were attached to the clamp of the twisting machine so that the gap between them was 500 mm. One clamp was fixed, the other clamp was rotated, the number of revolutions until the twist was completely unwound was measured, and the value obtained by doubling the number was determined as the number of twists of the cord. (3) Flexural fatigue resistance of rubber-reinforcing cord According to the Goodyear method described in JIS L1017, the time until the tube breaks (breaking life) is measured using a tube test piece, and this is measured for flexural fatigue resistance. Was used as an index.

In this example, a rubber sheet having the composition shown in Table 4 was wound around a drum, and the above-mentioned rubber-reinforcing cord was wound around the drum at an interval of 55 pieces / 10 cm. The sheet was rolled up. The rubber sheet / cord / rubber sheet trilayer thus obtained was removed from the drum and wound on a mandrel to form a tube. Furthermore, in the press machine, the rubber was heated at a temperature of 160 ° C. and a pressure of 9.8 MPa,
Vulcanization was performed under conditions of 30 minutes to prepare a tube test piece. In this way, the fiber reinforced rubber material (outer diameter 27 mm, inner diameter 13 m) in which the axial direction of the rubber tube and the cord orientation match
m, length 24 cm) was obtained.

The central portion of the fiber reinforced rubber material was bent at 90 °, air with a pressure of 0.3 MPa was fed into the tube, and both ends of the tube were moved in the same direction at a speed of 850 times / minute in an atmosphere at a temperature of 25 ° C. The tube was rotated and the time until the tube was broken (breaking life) was measured. (4) Rubber / Cord Adhesiveness The rubber / cord adhesiveness was determined by measuring the peeling adhesive force under the following two conditions: a room temperature dry state and a moisture absorption high temperature state.

In this example, a base material (rubber sheet: width 25 mm, length 230 m) containing rubber as a test piece.
m, thickness 4 mm) with 7 cords embedded in parallel near the surface layer (interval between cord centers 3 mm), 150 ° C, 30
The fiber-reinforced rubber material obtained by vulcanizing for 20 minutes at a pressing pressure of 20 kg / cm 2 was used. Here, the rubber sheet having the composition shown in Table 4 was used as the base material containing rubber. Room temperature drying condition: The force required to peel off three even-numbered cords from the rubber sheet at a speed of 100 mm / min out of the seven cords embedded in the fiber-reinforced rubber material as a test piece (peel adhesion) Was expressed as N / piece. The test piece press-vulcanized under the high temperature condition of moisture absorption was put in gauze and steam-treated at 155 ° C. for 30 minutes at a vapor pressure of 4 kg / cm ² , and then the peel adhesion strength was measured at room temperature under the same conditions as above. (Examples 1 to 5, Comparative Examples 1 and 2) Using the resin composition treatment liquids shown in Tables 1 and 2 and the RFL liquid shown in Table 3, a carbon fiber bundle for rubber reinforcement was prepared by the above-mentioned method. Further, a rubber sheet having the composition shown in Table 4 was used as a base material containing rubber, and a fiber reinforced rubber material was produced by the above-mentioned method. Table 5 shows the tube fatigue life, which is an index of flex fatigue resistance, and the peel adhesion strength, which is an index of adhesiveness between rubber and cord.

As can be seen from the evaluation results shown in Table 5, the cord according to the present invention exhibits extremely excellent fatigue resistance against repeated bending deformation, and has a high level even after being exposed to a high temperature and moisture absorption. It can be seen that it retains a level of rubber adhesion.

[0077]

[Table 1]

[0078]

[Table 2]

[0079]

[Table 3]

[0080]

[Table 4]

[0081]

[Table 5]

[0082]

EFFECTS OF THE INVENTION According to the present invention, a rubber-reinforcing material having a strong adhesion even between a carbon fiber and a rubber compound, even under a wet high temperature environment, and having excellent fatigue resistance is provided. be able to.

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) C08L 63/00 C08L 63/00 Z D02G 3/02 D02G 3/02 3/36 3/36 3/48 3 / 48 D06M 15/41 D06M 15/41 15/55 15/55 15/693 15/693 // D06M 101: 40 101: 40 F term (reference) 4F072 AA04 AA07 AB10 AB22 AC02 AC08 AC09 AC15 AD02 AD23 AG03 AG06 AG14 AH02 AH31 AK05 AK06 AL16 AL18 AL19 4J002 AC011 AC031 AC061 AC071 AC081 AC091 AC111 DA016 FA046 FB266 FD016 GM00 GM01 GN01 4L033 AA09 AB01 AB03 AC11 AC12 CA34 CA49 CA68 4L036 MA04 MA33 PA21 RA03 FA03 FA20 FA03 FA03 FA21 FA24 FA03 FA0 FA24 FA03 FA0 FA03 FA023

Claims (17)

[Claims] 1. When a small piece of carbon fiber bundle cut to a length of 20 mm is floated on the water surface, it begins to settle into water within 20 seconds,
A carbon fiber bundle for rubber reinforcement, characterized in that the knot strength of the carbon fiber bundle is 500 MPa or more. 2. A solubility parameter (SP value) of 8.0 to 1
^{2.0 (cal) 1/2 /} (cm) rubber-reinforcing carbon fiber bundle according to claim 1, sizing agent in the ^3/2 range is characterized in that granted. 3. The rubber-reinforcing carbon fiber bundle according to claim 1, wherein the carbon fiber surface is provided with a sizing agent in an amount of 0.1 to 1.5% by weight of the carbon fiber bundle. 4. The fineness of the carbon fiber bundle is 2000 to 100.
It is 00 dtex, The carbon fiber bundle for rubber reinforcement in any one of Claims 1-3 characterized by the above-mentioned. 5. The tensile strength of the carbon fiber bundle is 4000M.
The carbon fiber bundle for rubber reinforcement according to any one of claims 1 to 4, which has Pa or more. 6. The cross-sectional shape of the single fibers constituting the carbon fiber bundle is substantially a perfect circle.
The carbon fiber bundle for rubber reinforcement according to any one of to 5. 7. A resin composition containing rubber is added to 20 parts by weight of 100 parts by weight of the carbon fiber bundle according to claim 1.
A rubber reinforcing cord containing 80 parts by weight. 8. The rubber component in 100% by weight of the resin composition is 20 to 80% by weight.
The rubber reinforcing cord described in. 9. 20 to 20% by weight of said resin composition
The rubber-reinforcing cord according to claim 7, which contains 80% by weight of an epoxy resin. 10. The rubber reinforcing cord according to claim 9, wherein the epoxy resin is an aliphatic epoxy resin. 11. A cord surface with resorcinol / formalin /
A rubber latex (RFL) is adhered, wherein
10. The rubber reinforcing cord according to any one of 10. 12. The rubber-reinforcing cord according to claim 7, wherein the twist number of the cord is 100 times / m or less. 13. A fiber reinforced rubber material, characterized in that a base material containing rubber is reinforced by the rubber reinforcing cord according to any one of claims 7 to 12. 14. A base material comprising the rubber is selected from the group consisting mainly of natural rubber, chloroprene rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber or hydrogenated acrylonitrile-butadiene rubber. At least 1
The fiber-reinforced rubber material according to claim 13, which is a kind of rubber. 15. A belt made of the fiber-reinforced rubber material according to claim 13 or 14. 16. A tire using the fiber reinforced rubber material according to claim 13 or 14. 17. A hose made of the fiber reinforced rubber material according to claim 13 or 14.