JP5112202B2 - Carbon fiber composite material excellent in chlorine resistance and method for producing the same - Google Patents

Description

  The present invention relates to a carbon fiber composite material excellent in chlorine resistance and a method for producing the same.

  The rubber composition formed by blending carbon black as a reinforcing agent with ethylene / propylene rubber (EPDM) was excellent in various mechanical strengths. For example, free residual chlorine in seawater and tap water is a rubber composition. Oxidation and chlorination of the rubber surface of the product, after forming a cross-linked layer and a brittle layer, it causes cracks due to the influence of water flow vibration, etc., and the black component etc. peels off and floats in the piping system In some cases, improvement in chlorine resistance has been desired. For example, butterfly valves that may be used for such pipes in water, communal baths, pools, food production facilities, etc. due to the presence of free residual chlorine in fluids intended for sterilization, cleaning and decolorization with chlorine There was a rubber sheet (hereinafter referred to as a sealing member). Accordingly, a butterfly valve seal member that does not use carbon black as a reinforcing agent has been proposed (see, for example, Patent Document 1). Such a butterfly valve, because of its structure, has a large liquid contact area when compared to a seal member used in a stationary manner, and the wet lubrication fluid is applied to the seal member at a high speed to apply lubrication. Since the effect of the material fades in a short period of time, and the disc is a mechanism that slides while strongly pressing the seal member, the black component tends to be peeled off due to chlorine deterioration of the seal member.

In addition, a carbon fiber composite material in which carbon nanofibers and carbon black are uniformly dispersed in an elastomer has been proposed (see, for example, Patent Document 2).
Japanese Patent No. 2872830 JP 2007-39649 A

  The objective of this invention is providing the carbon fiber composite material excellent in chlorine resistance, and its manufacturing method.

The carbon fiber composite material excellent in chlorine resistance according to the present invention is
Look-containing ethylene-propylene rubber, and carbon nanofibers surface oxidation treatment by heat treatment at 600 ° C. to 800 ° C. in an atmosphere containing oxygen, an average particle diameter of carbon black 50Nm～10myuemu, a,
The carbon nanofibers have a surface oxygen concentration of 2.6 atm% to 4.6 atm% measured by X-ray photoelectron spectroscopy (XPS), and an average diameter of 4 nm to 230 nm.
5 parts by mass to 50 parts by mass of the carbon nanofibers and 10 parts by mass to 120 parts by mass of the carbon black are mixed with 100 parts by mass of the ethylene / propylene rubber.
In the carbon fiber composite material excellent in chlorine resistance according to the present invention,
The carbon nanofiber has an average diameter of 60 nm to 150 nm,
The compounding amount of the carbon nanofiber with respect to 100 parts by mass of the ethylene / propylene rubber may be 10 parts by mass to 40 parts by mass.

  According to the carbon fiber composite material having excellent chlorine resistance according to the present invention, surface-oxidized carbon nanofibers and carbon black having an average particle diameter of 50 nm to 10 μm are present in an aqueous solution. Since it is relatively stable with respect to chloric acid, hypochlorite ion, etc., there is little deterioration of rubber at the interface between these reinforcing agents and ethylene / propylene rubber, and it can be excellent in chlorine resistance. Moreover, according to the carbon fiber composite material excellent in chlorine resistance according to the present invention, since it is reinforced by the carbon nanofiber and the carbon black, it can have excellent mechanical strength.

The method for producing a carbon fiber composite material excellent in chlorine resistance according to the present invention,
A first carbon nanofiber having an average diameter of 4 nm to 250 nm manufactured by a vapor deposition method is subjected to an oxidation treatment by heat treatment at 600 ° C. to 800 ° C. in an oxygen-containing atmosphere . A first step of obtaining a carbon nanofiber of
A second step in which carbon black having an average particle size of 50 nm to 10 μm and the second carbon nanofiber are mixed in ethylene / propylene rubber and dispersed in the ethylene / propylene rubber by shearing force;
Only including,
The second carbon nanofiber has a surface oxygen concentration measured by X-ray photoelectron spectroscopy (XPS) of 2.6 atm% to 4.6 atm%,
In the second step, 5 to 50 parts by mass of the second carbon nanofiber and 10 to 120 parts by mass of the carbon black are blended with respect to 100 parts by mass of the ethylene / propylene rubber. It is characterized by that .

  According to the method for producing a carbon fiber composite material excellent in chlorine resistance according to the present invention, chlorine and chloride ions in which an aqueous solution contains carbon nanofibers subjected to surface oxidation treatment and carbon black having an average particle diameter of 50 nm to 10 μm. Carbon fiber composites that are relatively stable against hypochlorous acid, hypochlorite ions, etc., so that there is little deterioration of rubber at the interface between these reinforcing agents and ethylene / propylene rubber, and excellent chlorine resistance The material can be manufactured. Further, according to the method for producing a carbon fiber composite material excellent in chlorine resistance according to the present invention, a carbon fiber composite material having excellent mechanical strength is produced because it is reinforced by carbon nanofibers and carbon black. be able to.

In the method for producing a carbon fiber composite material excellent in chlorine resistance according to the present invention,
In the first step, the amount of increase in the oxygen concentration on the surface of the second carbon nanofiber relative to the oxygen concentration on the surface of the first carbon nanofiber measured by X-ray photoelectron spectroscopy (XPS) is 0. Oxidation treatment can be performed so that the concentration becomes 0.5 atm% to 2.6 atm%.

In the method for producing a carbon fiber composite material excellent in chlorine resistance according to the present invention,
In the first step, the increase rate of the oxygen concentration on the surface of the second carbon nanofiber relative to the oxygen concentration on the surface of the first carbon nanofiber measured by X-ray photoelectron spectroscopy (XPS) is 20 The oxidation treatment can be performed so as to be in a range of% to 120%.

In the method for producing a carbon fiber composite material excellent in chlorine resistance according to the present invention,
In the first step, the second carbon nanofiber can be obtained by reducing the mass of the first carbon nanofiber by 2% to 20%.
In the method for producing a carbon fiber composite material excellent in chlorine resistance according to the present invention,
The second carbon nanofiber has an average diameter of 60 nm to 150 nm,
The compounding amount of the carbon nanofiber with respect to 100 parts by mass of the ethylene / propylene rubber may be 10 to 40 parts by mass.

  Hereinafter, embodiments of the present invention will be described in detail.

A carbon fiber composite material excellent in chlorine resistance according to an embodiment of the present invention is composed of an ethylene / propylene rubber and carbon nano-particles subjected to surface oxidation treatment by heat treatment at 600 ° C. to 800 ° C. in an atmosphere containing oxygen. fiber and, seen containing a carbon black having an average particle size 50Nm～10myuemu, the said carbon nanofibers, X-ray photoelectron spectroscopy oxygen concentration of the surface as measured by (XPS) is 2.6atm% ~4.6atm% And an average diameter of 4 nm to 230 nm, and 100 parts by mass of the ethylene / propylene rubber, 5 parts by mass to 50 parts by mass of the carbon nanofibers, 10 parts by mass to 120 parts by mass of the carbon black, , Is blended .

The method for producing a carbon fiber composite material excellent in chlorine resistance according to an embodiment of the present invention includes an atmosphere containing oxygen of first carbon nanofibers having an average diameter of 4 nm to 250 nm produced by a vapor deposition method. A first step of obtaining a second carbon nanofiber having a surface oxidized by heat treatment at 600 ° C. to 800 ° C., carbon black having an average particle size of 50 nm to 10 μm, and the second the carbon nanofibers mixed into the ethylene-propylene rubber, seen including a second step of dispersing the said ethylene-propylene rubber in shear, and the second carbon nanofibers, X-ray photoelectron spectroscopy The surface oxygen concentration measured by (XPS) is 2.6 atm% to 4.6 atm%, and the second step is 100 masses of the ethylene / propylene rubber. Respect, the second carbon nanofibers 5 parts by mass to 50 parts by mass, wherein the blending, and the carbon black 10 parts by 120 parts by weight.

(I) Surface oxidized carbon nanofiber (first carbon nanofiber)
First, after describing the first carbon nanofiber used in the first step of the method for producing the carbon fiber composite material, the second carbon nanofiber obtained in the first step will be described.
The first carbon nanofiber is produced by, for example, a vapor deposition method. The vapor phase growth method is a method for producing first carbon nanofibers by gas phase pyrolysis of a gas such as hydrocarbon in the presence of a metal catalyst. The vapor phase growth method will be described in more detail. For example, an organic compound such as benzene or toluene is used as a raw material, an organic transition metal compound such as ferrocene or nickelcene is used as a metal catalyst, and these are used together with a carrier gas at a high temperature such as 400 ° C. A method of introducing a first carbon nanofiber on a substrate by introducing it into a reaction furnace set to a reaction temperature of ˜1000 ° C., a method of generating a first carbon nanofiber in a floating state,
Alternatively, a method of growing the first carbon nanofibers on the reaction furnace wall can be used. Alternatively, the first carbon nanofibers having an average diameter of 70 nm or less can be obtained by bringing metal-containing particles previously supported on a refractory support such as alumina or carbon into contact with a carbon-containing compound at a high temperature. The average diameter of the first carbon nanofibers produced by a vapor phase growth method have an average diameter of Ru 4nm~250nm der. The first carbon nanofiber is an untreated carbon nanofiber in the sense that the surface is not oxidized, and the dispersibility is preferably improved by oxidizing the surface.

  Thus, the first carbon nanofibers manufactured by the vapor phase growth method can be heat-treated at 2000 ° C. to 3200 ° C. in an inert gas atmosphere before the oxidation treatment. The heat treatment temperature is more preferably 2500 ° C to 3200 ° C, and particularly preferably 2800 ° C to 3200 ° C. It is preferable that the heat treatment temperature is 2000 ° C. or higher because impurities such as amorphous deposits and remaining catalytic metal deposited on the surface of the first carbon nanofiber during vapor phase growth are removed. Further, when the heat treatment temperature of the first carbon nanofiber is 2500 ° C. or more, the skeleton of the first carbon nanofiber is graphitized (crystallized), the defects of the first carbon nanofiber are reduced, and the strength is increased. It is preferable because it improves. In addition, it is preferable if the heat treatment temperature of the first carbon nanofiber is 3200 ° C. or less because the graphite skeleton is not easily broken by the sublimation of graphite. The first carbon nanofiber graphitized in this way is an untreated carbon nanofiber because it has not been oxidized, and has excellent strength, thermal conductivity, electrical conductivity, and the like due to graphitization. .

  Examples of the first carbon nanofibers include so-called carbon nanotubes. The carbon nanotube has a structure in which one surface of graphite having a carbon hexagonal mesh surface is wound in one layer or multiple layers. A carbon material partially having a carbon nanotube structure can also be used. In addition to the name “carbon nanotube”, it may be called “graphite fibril nanotube” or “vapor-grown carbon fiber”.

(Second carbon nanofiber)
The second carbon nanofibers can be obtained by oxidizing the surface of the first carbon nanofibers manufactured by the vapor phase growth method. The oxidation treatment will be described later in the column of the method for producing the carbon fiber composite material. The second carbon nanofibers, the oxygen concentration measured by X-ray photoelectron spectroscopy of the surface (XPS) is Ru 2.6atm% ~4.6atm% der. The second carbon nanofiber has an oxygen concentration measured by X-ray photoelectron spectroscopy (XPS) on the surface thereof of preferably 3.0 atm% to 4.0 atm%, more preferably 3.1 atm% to 3.7 atm. %. As described above, since the surface of the second carbon nanofiber is appropriately oxidized, the surface reactivity between the second carbon nanofiber and the ethylene / propylene rubber is improved. The carbon nanofibers can be more uniformly dispersed. The second carbon nanofiber may have a mass obtained by reducing the mass of the first carbon nanofiber by 2% to 20%. The second carbon nanofibers, 1600 cm ^-1 near the peak intensity ratio D of around 1300 cm ^-1 to the peak intensity G of (D / G) preferably measured by Raman scattering spectroscopy is 0.12 to 0.22 is there. The second carbon nanofibers, the nitrogen adsorption specific surface area is preferably ^{34m 2} / ^g~58m 2 / g. The second carbon nanofibers have an average diameter of Ru 4nm~230nm der. In particular, the average diameter of the second carbon nanofibers is preferably 60 nm to 150 nm. The second carbon nanofiber is preferably dispersible with respect to the matrix material when the diameter is 4 nm or more, and conversely when the diameter is 230 nm or less, the flatness of the surface of the matrix material is not easily impaired. When the average diameter of the second carbon nanofiber is 60 nm or more, the dispersibility and the flatness of the surface are excellent. When the average diameter is 150 nm or less, the number of carbon nanofibers increases even with a small addition amount. The performance of the first carbon nanofiber can be saved. The aspect ratio of the second carbon nanofiber is preferably 50 to 200.

  According to the second carbon nanofiber, since the surface is appropriately oxidized, the surface reactivity between the carbon nanofiber and another material, for example, the matrix material in the composite material, is improved. The wettability of can be improved. By using carbon nanofibers with improved wettability in this way, for example, the rigidity and flexibility of the carbon fiber composite material can be improved. In particular, in the case of the graphitized first carbon nanofiber, wettability between the second carbon nanofiber and the matrix material can be improved by appropriately oxidizing the surface with relatively low reactivity. The dispersibility can be improved, and for example, the same physical properties can be obtained even by adding a smaller amount of the second carbon nanofiber than in the prior art. Since the surface of conventional carbon black with a relatively small diameter is activated by chlorine, chlorine ions, hypochlorous acid, and hypochlorite ions in the aqueous solution, the ethylene / propylene rubber in contact with the surface is oxidized and deteriorated. I think that. On the other hand, the second carbon nanofiber subjected to the surface oxidation treatment has many portions in which carbon atoms on the surface are substituted with oxygen atoms, and the oxygen atoms on the surface are molecules of ethylene / propylene rubber. It is considered that the surface is hardly activated by chlorine, chlorine ions, hypochlorous acid, and hypochlorite ions. Therefore, the ethylene / propylene rubber blended with the second carbon nanofibers is excellent in chlorine resistance as compared with the blended with the conventional small-diameter carbon black.

The blending amount of the second carbon nanofiber with respect to the ethylene / propylene rubber can be appropriately adjusted depending on the degree of reinforcement depending on the use of the carbon fiber composite material and the blending amount of the carbon black blended together. per 100 parts by mass, it blended 5 parts by mass to 50 parts by mass of the second carbon nanofibers. If the blending amount of the second carbon nanofiber is 5 parts by mass or more, a reinforcing effect for ethylene / propylene rubber can be obtained by increasing the blending amount of carbon black. Is also preferable.

(II) Carbon black As long as the carbon black has an average particle diameter of 50 nm to 10 μm, various grades of carbon black using various raw materials can be used alone or in combination. Carbon black has an average particle size of 50 to 10 μm, more preferably an average particle size of 50 to 150 nm. Ethylene / propylene rubber blended with carbon black having a relatively large particle size in this way is excellent in chlorine resistance, and can be divided into a large amount of ethylene / propylene rubber system, so the blending amount of ethylene / propylene rubber In addition, the amount of the second carbon nanofiber can be saved, which is economically excellent. Carbon black with a small particle size, which was blended in conventional carbon fiber composite materials, is easily activated by chlorine, chlorine ions, hypochlorous acid, and hypochlorite ions in aqueous solution, and blended with ethylene / propylene rubber. In such a case, it is presumed that the deterioration of the ethylene / propylene rubber proceeds from the interface between the carbon black and the ethylene / propylene rubber by an oxidation reaction. Therefore, when the average particle size of the carbon black is less than 50 nm, the reinforcing property is excellent but the chlorine resistance tends to be inferior. Further, since the reinforcing effect tends to be inferior when the average particle size is larger than 10 μm, it is preferable to use carbon black having an average particle size of 10 μm or less from the viewpoint of economy. As such carbon black, for example, carbon black of grades such as SRF, MT, FT, Austin black and GPF can be adopted.

The blending amount of carbon black with respect to ethylene / propylene rubber can be appropriately adjusted according to the degree of reinforcement depending on the use of the carbon fiber composite material and the blending amount of the second carbon nanofiber blended together. per 100 parts by mass, blending 10 parts by mass to 120 parts by weight of carbon black. If the blending amount of carbon black is 10 parts by mass or more, a reinforcing effect for ethylene / propylene rubber can be obtained, and the blending amount of ethylene / propylene rubber and second carbon nanofibers can be reduced. The following is preferable because it can be processed and can be mass-produced.

(III) Ethylene / propylene rubber As the ethylene / propylene rubber, EPDM (ethylene-propylene-diene copolymer) is preferably used. Further, the ethylene / propylene rubber according to the present embodiment includes a third component such as ethylidene norbornene in order to obtain heat resistance, cold resistance, and sealability necessary for the piston seal member, and is a copolymer of ethylene and propylene. The ratio is preferably 45% to 80% EPDM in ethylene content. The weight average molecular weight of the ethylene / propylene rubber is usually desirably 50,000 or more, more preferably 70,000 or more, and particularly preferably about 100,000 to 500,000. When the molecular weight of the ethylene / propylene rubber is within this range, the ethylene / propylene rubber molecules are entangled with each other and connected to each other, so that the ethylene / propylene rubber easily penetrates into the aggregated carbon nanofibers. Great effect to separate fibers. If the molecular weight of the ethylene / propylene rubber is less than 5000, the ethylene / propylene rubber molecules cannot be sufficiently entangled with each other, and the effect of dispersing the carbon nanofibers tends to be small even if a shearing force is applied in the process described later. There is. On the other hand, if the molecular weight of the ethylene / propylene rubber is larger than 5 million, the ethylene / propylene rubber becomes too hard and the workability tends to be lowered.

(IV) Manufacturing method of carbon fiber composite material The manufacturing method of a carbon fiber composite material has a 1st process and a 2nd process.
(First step)
First, the 1st process in the manufacturing method of a carbon fiber composite material is demonstrated. In the first step, the first carbon nanofibers produced by the vapor phase growth method are oxidized to obtain second carbon nanofibers whose surfaces are oxidized. As the first carbon nanofiber, those subjected to the graphitization treatment can be used. The surface oxygen concentration measured by X-ray photoelectron spectroscopy (XPS) of the second carbon nanofiber obtained in the first step is 2.6 atm% to 4.6 atm%, preferably 3.0 atm%. It is -4.0 atm%, More preferably, it is 3.1 atm%-3.7 atm%. The second carbon nanofibers are desirably oxidized to such an extent that the oxygen concentration on the surface thereof is increased by 0.2 atm% or more from the oxygen concentration on the surface of the first carbon nanofibers. In the first step, the amount of increase in the oxygen concentration on the surface of the second carbon nanofiber relative to the oxygen concentration on the surface of the first carbon nanofiber measured by X-ray photoelectron spectroscopy (XPS) is 0.5 atm%. Oxidation treatment can be performed so as to be ˜2.6 atm%. The increase amount of the surface oxygen concentration of the second carbon nanofiber relative to the surface oxygen concentration of the first carbon nanofiber is more preferably 0.9 atm% to 1.9 atm%, and further 1.0 atm%. It is preferable that it is -1.6atm%. In the first step, the rate of increase in the oxygen concentration on the surface of the second carbon nanofiber relative to the oxygen concentration on the surface of the first carbon nanofiber measured by X-ray photoelectron spectroscopy (XPS) is 20%. The oxidation treatment can be performed so as to be ˜120%. The increase rate of the surface oxygen concentration of the second carbon nanofibers relative to the surface oxygen concentration of the first carbon nanofibers is more preferably 43% to 90%, and more preferably 48% to 76%. Is preferred. Thus, the surface reactivity of the second carbon nanofiber and ethylene / propylene rubber is improved by appropriately oxidizing the surface of the second carbon nanofiber, and the carbon nanofiber in the ethylene / propylene rubber is improved. It is possible to improve the fiber dispersion failure. The first step, we heat treated at 600 ° C. to 800 ° C. in an atmosphere containing oxygen first carbon nanofibers. For example, the first carbon nanofibers are placed in a furnace in an air atmosphere, set to a predetermined temperature in the temperature range of 600 ° C. to 800 ° C., and heat-treated, whereby the surface of the second carbon nanofibers has a desired oxygen content. Can be oxidized to concentration. The heat treatment time in the first step is a time for holding the first carbon nanofibers in a heat treatment furnace at a predetermined temperature, and can be, for example, 10 minutes to 180 minutes. The atmosphere containing oxygen may be the air, an oxygen atmosphere, or an atmosphere in which an oxygen concentration is appropriately set. A sufficient oxygen concentration may be present in the atmosphere so that the surface of the second carbon nanofiber is oxidized to a desired oxygen concentration in the first step. The temperature of the heat treatment can be appropriately set in order to obtain a desired oxidation treatment in the range of 600 ° C to 800 ° C. Usually, since the first carbon nanofibers burn and cause great damage to the fibers at around 800 ° C., it is desirable to set the temperature setting and the heat treatment time carefully while repeating the experiment. The heat treatment temperature and heat treatment time can be appropriately adjusted depending on the oxygen concentration in the furnace used in the first step, the inner volume of the furnace, the amount of the first carbon nanofibers to be treated, and the like. The mass of the second carbon nanofibers thus oxidized in the first step is preferably reduced by 2% to 20%, for example, from the mass of the first carbon nanofibers. It can be estimated that the second carbon nanofibers are appropriately oxidized. If the mass of the second carbon nanofiber is less than 2% less than the mass of the first carbon nanofiber, the oxygen concentration on the surface of the second carbon nanofiber is low, and it tends to be difficult to improve wettability. There is. In addition, the second carbon nanofibers whose weight is reduced by more than 20% from the mass of the first carbon nanofibers, although the wettability is almost the same as the second carbon nanofibers whose weight loss is 20% or less. However, the loss due to the reduction of the carbon nanofibers due to the oxidation treatment is large, and it tends to be economically disadvantageous with respect to the energy consumption of the heat treatment. This is because when the surface of the first carbon nanofiber is oxidized, a part of the carbon on the surface of the first carbon nanofiber is vaporized as carbon dioxide gas to be reduced. It is preferable because it can be estimated that the fiber length is not almost shortened unless the mass of the second carbon nanofiber exceeds 20% of the mass of the first carbon nanofiber. The oxygen concentration on the surface of the second carbon nanofiber can be analyzed by XPS (X-ray photoelectron spectroscopy). The analysis of the oxygen concentration by XPS is performed in order to remove impurities adhering to the surface of the second carbon nanofiber, for example, 0.5 to 1.0 minutes of argon gas with respect to the second carbon nanofiber before measurement. It is preferable to perform analysis after etching to bring out the clean surface of the second carbon nanofiber. The argon gas concentration in the argon gas etching ^{5 × 10 -2 Pa~20 × 10 -2} Pa, the pressure of argon gas (gauge pressure) 0.4MPa~0.5MPa is preferred. In addition, for analysis of oxygen concentration by XPS, for example, a carbon tape which is a conductive adhesive is applied on a metal base of an XPS apparatus, and a second carbon nanofiber is sprinkled on the carbon tape to adhere to the carbon tape. It is preferable to carry out in a state in which excess second carbon nanofibers that have not adhered to the carbon tape are shaken off. Thus, in the analysis of the oxygen concentration by XPS, it is preferable to analyze in the state as close to the powder as possible without pressing the second carbon nanofibers onto the carbon tape and solidifying it into a block shape.

The second carbon nanofibers obtained by the first step, the ratio of the peak intensity D of around 1300 cm ^-1 to the peak intensity G of around 1600 cm ^-1 measured by Raman scattering spectroscopy (D / G) is preferably Is 0.12-0.22. The Raman peak ratio (D / G) of the second carbon nanofiber is larger than the Raman peak ratio (D / G) of the first carbon nanofiber because there are many defects in the crystal on the surface. The second carbon nanofiber is desirably oxidized to such an extent that its Raman peak ratio (D / G) increases by 0.02 or more than the Raman peak ratio (D / G) of the first carbon nanofiber. The second carbon nanofibers, the nitrogen adsorption specific surface area is preferably ^{34m 2} / ^g~58m 2 / g. The nitrogen adsorption specific surface area of the second carbon nanofiber is larger than the nitrogen adsorption specific surface area of the first carbon nanofiber because the surface thereof is rough. It is desirable that the ^second carbon nanofibers be oxidized to such an extent that the nitrogen adsorption specific surface area increases by 9 m ² / g or more than the nitrogen adsorption specific surface area of the first carbon nanofibers. The average diameter of the first carbon nanofibers used in the first step is Ri 4nm~250nm der, the average diameter of the second carbon nanofibers obtained by the first step is Ru 4nm~230nm der. By using such second carbon nanofibers, surface reactivity with ethylene / propylene rubber can be improved, and wettability with respect to ethylene / propylene rubber can be improved.

  The blending amount of the second carbon nanofibers into the ethylene / propylene rubber can be set according to the use, but because the second carbon nanofibers have improved wettability with the ethylene / propylene rubber, For example, when a carbon fiber composite material having the same rigidity is produced, the blending amount is small and economical.

(Second step)
In the second step of the method for producing a carbon fiber composite material, carbon black having an average particle diameter of 50 nm to 10 μm and the second carbon nanofiber obtained in the first step are mixed with ethylene / propylene rubber, Disperse in the ethylene / propylene rubber by shearing force.
As the second step, there is a method in which the ethylene / propylene rubber and the second carbon nanofiber are supplied to a known mixer such as an open roll, a single or twin screw extruder, a Banbury mixer, a kneader, and kneaded. Can be mentioned. The filler other than the second carbon nanofibers such as carbon black is preferably supplied to the mixer before supplying the second carbon nanofibers. The step of kneading the ethylene / propylene rubber, the carbon black, and the second carbon nanofiber includes the first kneading of the ethylene / propylene rubber, the carbon black, and the second carbon nanofiber at a first temperature. A step, a second kneading step of kneading the mixture obtained in the first kneading step at a second temperature, and a third kneading step of passing through the mixture obtained in the second kneading step. Can be included. In the present embodiment, an example in which a closed kneading method is used as the first kneading step and the second kneading step and an open roll method is used as the third kneading step will be described in detail with reference to FIGS. To do.

FIG. 1 is a diagram schematically showing a mixing process by a closed kneader 11 using two rotors. FIG. 2 is a diagram schematically showing a third kneading step (thinning) of the carbon fiber composite material by an open roll machine.
In FIG. 1, the closed kneading machine 11 includes a first rotor 12 and a second rotor 14.

(Mixing process)
First, the ethylene / propylene rubber 200 is introduced from the material supply port 16 of the closed kneader 11 and the first and second rotors 12 and 14 are rotated. Further, a predetermined amount of carbon black 212 and second carbon nanofiber 220 are added to the chamber 18, and the first and second rotors 12 and 14 are further rotated, whereby the ethylene / propylene rubber 200 and the carbon black 212 are rotated. And mixing with the 2nd carbon nanofiber 220 is performed.

(First kneading step)
Next, a first kneading step is performed in which the mixture obtained in the mixing step is further kneaded with a high shearing force by rotating the first and second rotors 12 and 14 at a predetermined speed ratio. In the first kneading step, in order to obtain as high a shearing force as possible, mixing of the ethylene / propylene rubber and the second carbon nanofiber is performed at a first temperature that is 50 to 100 ° C. lower than the second kneading step. . The first temperature is preferably a first temperature of 0 to 50 ° C, more preferably 5 to 30 ° C. The first temperature may be set according to the temperature of the chamber 18, may be set according to the temperatures of the first and second rotors 12 and 14, or the speed ratio may be controlled while measuring the temperature of the mixture. Various temperature controls may be performed. In addition, when the first kneading step is performed in the same closed kneading machine 11 following the above-described mixing step, the first temperature may be set in advance.

  When non-polar EPDM (ethylene-propylene-diene copolymer rubber) is used as the ethylene-propylene rubber 200, the second carbon nanofiber 220 is made of ethylene-propylene while leaving agglomerates in the first kneading step. Disperses throughout the rubber 200.

(Second kneading step)
Furthermore, the mixture obtained by the first kneading step is put into another closed kneader, and the second kneading step is performed. In the second kneading step, the ethylene / propylene rubber molecules are cut to generate radicals, so that the kneading is performed at a second temperature that is 50 to 100 ° C. higher than the first temperature. The hermetic kneader used in the second kneading step is heated to the second temperature by a heater built in the rotor or a heater built in the chamber, and the second kneading machine is higher than the first temperature. The second kneading step can be performed at a temperature of The second temperature can be appropriately selected depending on the type of ethylene / propylene rubber used, but is preferably 50 to 150 ° C. By performing the second kneading step in this manner, the ethylene / propylene rubber molecules are cleaved to generate radicals, and the second carbon nanofibers easily bind to the ethylene / propylene rubber molecule radicals.

(Third kneading step)
And the mixture 36 obtained by the 2nd kneading | mixing process is further injected | thrown-in to the open roll 30 set to the 1st temperature, and as shown in FIG. Perform 10 to 10 times and dispense. The roll interval d (nip) between the first roll 32 and the second roll 34 is set to 0 to 0.5 mm, for example, 0.3 mm, where the shearing force is larger than that in the first and second kneading steps. The temperature is set to the same third temperature of 0 to 50 ° C., more preferably 5 to 30 ° C., as in the first kneading step. When the surface speed of the first roll 32 is V1, and the surface speed of the second roll 34 is V2, the surface speed ratio (V1 / V2) between the two in the thin passage is 1.05 to 3.00. Preferably, it is more preferably 1.05 to 1.2. By using such a surface velocity ratio, a desired shear force can be obtained. The thinned mixture 36 is rolled with a roll and dispensed into a sheet. The third kneading step is a finishing dispersion step in which the second carbon nanofibers are further uniformly dispersed in the ethylene / propylene rubber, and is effective when more uniform dispersibility is required. By this third kneading step (thinning step), the ethylene / propylene rubber in which radicals are generated acts so as to pull out the second carbon nanofibers one by one, thereby further dispersing the second carbon nanofibers. it can. In addition, a vulcanizing agent (crosslinking agent) can be added in the third kneading step to uniformly disperse the vulcanizing agent.

  In this way, by performing the first kneading step at the first temperature, the second carbon nanofibers can be dispersed throughout the ethylene / propylene rubber with a high shearing force, and further, the second carbon nanofiber can be dispersed at the second temperature. By performing the kneading step and the third kneading step at the first temperature, the agglomerates of the second carbon nanofibers can be released by the radicals of the ethylene / propylene rubber molecules. According to the present embodiment, when the mixture is extruded from between narrow rolls in the third kneading step, the mixture is deformed thicker than the roll interval by the restoring force due to the elasticity of the ethylene / propylene rubber. It can be inferred that the deformation causes the mixture subjected to a strong shear force to flow more complicatedly and disperse the second carbon nanofibers in the ethylene / propylene rubber. The second carbon nanofibers once dispersed are prevented from reaggregating due to chemical interaction with the ethylene / propylene rubber, and can have good dispersion stability. Accordingly, the second carbon nanofibers can be dispersed throughout the nonpolar ethylene / propylene rubber such as EPDM, and a carbon fiber composite material free from aggregates of the second carbon nanofibers can be produced. In addition, the wettability with the ethylene / propylene rubber is improved by appropriately oxidizing the surface of the second carbon nanofibers.

  In the first and second kneading steps in which the second carbon nanofibers are dispersed in the ethylene / propylene rubber by a shearing force, it is preferable to use a closed kneader from the viewpoint of workability. The kneader may be used. As the closed kneader, a tangential type or meshing type such as a Banbury mixer, a kneader, or a Brabender can be adopted. The first, second, and third kneading steps are not limited to the above-described closed kneading method and open roll method, and can be performed by a multi-screw extrusion kneading method (for example, a twin-screw extruder). The kneader can be selected in combination as appropriate according to the production amount. In particular, the open roll method in the third kneading step is preferable because it can measure and manage not only the roll temperature but also the actual temperature of the mixture.

  A method for producing a carbon fiber composite material is generally adopted by further mixing a vulcanizing agent with the dispensed sheet-like mixture after passing through, or mixing a vulcanizing agent during any kneading step. For example, by molding, such as injection molding, transfer molding, press molding, extrusion molding, calendering, etc. into the shape of seal members required for products such as various piping equipment, It can be heated and vulcanized by a vulcanization method or the like to form a sealing member for piping equipment.

  In the method for producing a carbon fiber composite material according to the present embodiment, a compounding agent usually used for processing of ethylene / propylene rubber can be added. A well-known thing can be used as a compounding agent. Examples of the compounding agent include a crosslinking agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization retarder, a softening agent, a plasticizer, a curing agent, a reinforcing agent, a filler, an antiaging agent, and a coloring agent. it can. These compounding agents can be introduced into the ethylene / propylene rubber before or after the introduction of the second carbon nanofibers in an open roll, for example.

(V) Carbon Fiber Composite Material Next, the carbon fiber composite material will be described below with reference to FIGS. 3 and 4.
FIG. 3 is a longitudinal sectional view showing a schematic configuration of a butterfly valve which is an embodiment of the piping equipment. FIG. 4 is a cross-sectional view taken along the line XX ′ of FIG. 3 for explaining the opening / closing operation of the butterfly valve which is one embodiment of the piping equipment.
The carbon fiber composite material can be used as a seal member for various piping equipment such as piping for various fluids and valves for opening and closing the flow paths of these fluids. Here, an embodiment of the piping equipment shown in FIGS. 3 and 4 is used. The outline of a structure of a sealing member is demonstrated using the butterfly valve 20 which is. The butterfly valve 20 has an annular seal member (seat ring, seat rubber, rubber liner or rubber) obtained by the manufacturing method described in (IV) above on the inner peripheral surface of a cylindrical body 21 made of a rigid material such as metal. A disc-like disc 24 is disposed inside the seal member 22. Cylindrical stems 23 and 23 are mounted on the center axis of the disc 24 so as to protrude from the upper and lower sides of the disc 24, and the stems 23 and 23 are rotatably mounted through the body 21 and the seal member 22. Yes. The outer peripheral surface 24 a of the disc 24 rotates the disc 24 to press the outer peripheral surface 24 a against the seal surface 22 a on the inner peripheral surface of the seal member 22 to close the valve. Therefore, the fluid flow path 28 in the valve can be opened and closed by rotating the disc 24 around the longitudinal axis of the stems 23 and 23. In the butterfly valve 20 having such a structure, the wetted area of the seal member 22 is large, the effect of the applied lubricant is easily lost in a short period of time, and the disk 24 slides strongly pressing the seal member 22. Due to the mechanism, there was a tendency for the black component to be peeled off due to the chlorine deterioration of the seal member 22, but the black component was peeled off by using such a seal member 22 for piping equipment having excellent chlorine resistance. Can be reduced.

  Piping equipment includes gate valves, ball valves, needle valves, check valves, ball valves, cocks, butterfly valves, diaphragm valves, safety valves, relief valves, pressure reducing valves, control valves, steam traps, solenoid valves, ventilation Valves, valves such as water taps, and screwed joints, welded joints, weld joints, fusion joints, adhesive joints, quick fluid joints, bite joints, tightening joints, expansion joints, clamp joints, Refers to joints such as one-touch joints, slide joints, compression joints, pipe joints, rolled thread joints, insertion joints, coupling joints, housing joints, and flexible joints.

  The carbon fiber composite material that can be used for such a sealing member includes ethylene-propylene rubber, surface-oxidized second carbon nanofibers, and carbon black having an average particle size of 50 nm to 10 μm, Excellent chlorine resistance. The surface-treated second carbon nanofiber may have a surface oxygen concentration of 2.6 atm% to 4.6 atm% as measured by X-ray photoelectron spectroscopy (XPS). The second carbon nanofibers are uniformly dispersed in the ethylene / propylene rubber. Since the second carbon nanofibers are oxidized, the wettability with the ethylene / propylene rubber is improved, and the rigidity and flexibility of the carbon fiber composite material are improved. In particular, the surface-oxidized second carbon nanofibers and carbon black having an average particle size of 50 nm to 10 μm are relatively stable against chlorine, chlorine ions, hypochlorous acid, and hypochlorite ions. Excellent chlorine resistance as a carbon fiber composite material. The carbon fiber composite material is reinforced by blending 5 to 50 parts by mass of second carbon nanofibers and 10 to 120 parts by mass of carbon black with respect to 100 parts by mass of ethylene / propylene rubber. From the viewpoints of properties, workability, economy, etc. Such a carbon fiber composite material excellent in chlorine resistance can be suitably used as a sealing material for piping equipment such as piping and valves for aqueous solutions with high chlorine concentration.

Examples of the present invention will be described below, but the present invention is not limited thereto. (1) Surface oxidation treatment of carbon nanofibers (1-1) A spray nozzle is attached to the top of a vertical heating furnace (inner diameter 17.0 cm, length 150 cm). The furnace wall temperature (reaction temperature) is raised to and maintained at 1000 ° C., and 20 g / min of a benzene liquid raw material containing 4% by weight of ferrocene is supplied from the spray nozzle at a flow rate of hydrogen gas of 100 L / min. To be sprayed directly. The shape of the spray at this time is a conical side surface (trumpet shape or umbrella shape), and the apex angle of the nozzle is 60 °. Under these conditions, ferrocene was pyrolyzed to produce iron fine particles, which became seeds, which produced and grown carbon nanofibers from carbon produced by pyrolysis of benzene. The carbon nanofibers grown by this method were continuously produced for 1 hour while being scraped off at intervals of 5 minutes.
The carbon nanofibers produced by the vapor phase growth method were graphitized by heat treatment at 2800 ° C. in an inert gas atmosphere. The graphitized first (untreated) carbon nanofiber (shown as “CNT-N” in Table 1) has an average diameter of 87 nm, an average length of 10 μm, a Raman peak ratio (D / G) of 0.08, and nitrogen adsorption. The specific surface area was 25 m ² / g and the surface oxygen concentration was 2.1 atm%.
(1-2) 100 g of graphitized first carbon nanofibers are placed in a heating furnace (desktop electric furnace AMF-20N manufactured by Asahi Rika Seisakusho Co., Ltd.) in the atmosphere, and the temperatures (575 ° C. to 720 ° C.) and time shown in Table 1 The second carbon nanofibers were obtained by performing an oxidation treatment by holding in a heating furnace (for 1 hour or 2 hours) and performing a heat treatment.
The temperature setting of the heating furnace was set by looking at the results of measuring the mass reduction of the first carbon nanofibers using the TG (Thermal Mass Spectrometry) method. In the TG (Thermal Mass Spectrometry) method, the mass decrease when the temperature of the first carbon nanofiber was raised in the atmosphere was measured, and the mass change of the second carbon nanofiber with respect to the temperature as shown in FIG. 5 was shown. . At this time, the rate of temperature increase was 10 ° C./min, and the atmosphere was air (compressed air 200 ml / min). From this measurement result, the heating furnace is set between 600 ° C. at which the mass of the first carbon nanofiber starts to decrease (oxidize) and 800 ° C. at which the mass reduction of the first carbon nanofiber is 100% (burns out). As shown in FIG. 5, five types of second carbon nanofibers were obtained. As shown in Table 1, the second carbon nanofibers are “CNT-A (575 ° C.)”, “CNT-B (615 ° C.)”, “CNT-C (650 ° C.) according to the set temperature of the heating furnace. ) ”,“ CNT-D (690 ° C.) ”, and“ CNT-E (720 ° C.) ”. The actual temperature in the heating furnace was in the range of ± 30 ° C. with respect to the set temperature.
Further, the Raman peak ratio (D / G), the nitrogen adsorption specific surface area, and the surface oxygen concentration were measured for the five types of second carbon nanofibers, and the results are shown in Table 1. Further, based on the measurement results of the oxygen concentration on the surfaces of the first and second carbon nanofibers, the surface oxygen concentration (a) of the first carbon nanofibers (“CNT-N”) before the oxidation treatment is performed. The amount of increase in surface oxygen concentration (b) (c = b−a) and the rate of increase in surface oxygen concentration (d = 100 · c / a) of each second carbon nanofiber were calculated and shown in Table 1. Raman peak ratio, KAISER OPTICAL SYSTEM Co. HOLOLAB-5000 Type: peak intensity at around 1300 cm ^-1 to the peak intensity G in the vicinity of 1600 cm ^-1 in the second carbon nanofibers by Raman scattering spectroscopy using a (532nmND YAG) The ratio of D (D / G) was measured. The nitrogen adsorption specific surface area (m ² / g) was measured using NOVA3000 type (nitrogen gas) manufactured by Yuasa Ionics. The oxygen concentration on the surface of the second carbon nanofiber was measured using XPS (X-ray Photoelectron Spectroscopy). Specifically, first, the second carbon nanofiber is sprinkled on the carbon tape on the metal base to adhere to the carbon tape, and the excess second carbon nanofiber that did not adhere to the carbon tape is shaken off and removed. Then, a metal base was mounted in the XPS apparatus. As the XPS device, “JPS-9200 for X-ray photoelectron spectrometer for microanalysis manufactured by JEOL Ltd. was used. Next, the second carbon nanofiber as a powder sample was added with an argon gas concentration of 8 × 10 × 10. ^-2 Pa, argon gas etching was performed for 0.5 minutes to bring out the clean surface of the second carbon nanofiber, and the X-ray source of the XPS apparatus had an analysis diameter of 1 mm, an anti-cathode Al / Mg twin target, The oxygen concentration on the surface of the second carbon nanofiber was measured at an acceleration voltage of 10 kV and an emission current of 30 mA, and the elements on the surface of the second carbon nanofiber detected by XPS were oxygen and carbon.

(2) Preparation of carbon fiber composite material samples of Examples 1 to 4 and Comparative Examples 1 to 5 As Examples 1 to 4 and Comparative Examples 1 to 4 samples, an open roll (roll set temperature 20 ° C.) A predetermined amount of ethylene / propylene rubber shown in FIG. 3 was charged, carbon black, carbon nanofibers, oil, and the like were charged into the ethylene / propylene rubber, and after the mixing step, the first kneading step was performed and taken out from the roll. Further, the mixture was again put into an open roll set at a roll temperature of 100 ° C., and taken out by performing a second kneading step.
Next, this mixture was wound around an open roll (roll temperature 10 to 20 ° C., roll interval 0.3 mm), and thinning was repeated 5 times. At this time, the surface speed ratio of the two rolls was set to 1.1. Further, the roll gap was set to 1.1 mm, and the sheet obtained through thinning was put in and dispensed.
An organic peroxide and a co-crosslinking agent were blended and mixed with the non-crosslinked sheet obtained through thinning, and the mixture was put into an open roll having a roll gap set to 1.1 mm and dispensed. Sheets that were dispensed and cut to mold size were set in a mold, and were subjected to compression molding at 175 ° C., 100 kgf / cm ² for 20 minutes, and the crosslinked bodies of Examples 1 to 4 and Comparative Examples 1 to 4 having a thickness of 1 mm. A carbon fiber composite material and a rubber composition sample were obtained.
In Tables 2 and 3, “SRF-CB” is SRF grade carbon black having an average particle diameter of 69 nm, “MT-CB” is MT grade carbon black having an average particle diameter of 122 nm, and “EPDM” is manufactured by JSR Corporation. The ethylene-propylene-diene copolymer (EPDM) was trade name EP24 (Mooney viscosity (ML _{1 + 4} , 125 ° C.) 42, ethylene content 54 mass%, diene content 4.5 mass%). In Tables 2 and 3, “CNT-C” is the second carbon nanofiber having a surface oxygen concentration of 3.5 atm% obtained in the above (1), and “CNT-N” is not oxidized. 1 carbon nanofiber. In Tables 2 and 3, “CNT-F” means that the carbon nanofibers produced by the vapor phase growth method in (1-1) are not graphitized, and the gas This carbon nanofiber was improved in wettability with the matrix by heat treatment at a heat treatment temperature (1200 ° C.) higher than the reaction temperature in the phase growth method, and was used for blending the rubber composition sample of Comparative Example 2.

In addition, as Comparative Example 5, the following various measurements were performed using a sheet-like sample molded with the same composition as the sealing member for the current butterfly valve. The rubber composition for molding the current seal member is blended with EPDM in a predetermined amount of FEF (average particle size 43 nm) and HAF (average particle size 28 nm).

(3) Measurement of hardness (Hs) The rubber hardness (JIS-A) of the carbon fiber composite material samples and rubber composition samples of Examples 1 to 4 and Comparative Examples 1 to 5 was measured based on JIS K 6253. The measurement results are shown in Tables 4 and 5.

(4) Measurement of tensile strength (Tb) and elongation at break (Eb) Test pieces obtained by cutting the carbon fiber composite material samples and rubber composition samples of Examples 1 to 4 and Comparative Examples 1 to 5 into a 1A dumbbell shape The tensile strength (MPa) and elongation at break (%) were measured by conducting a tensile test based on JIS K6251 using a tensile tester manufactured by Toyo Seiki Co., Ltd. at 23 ± 2 ° C. and a tensile speed of 500 mm / min. These results are shown in Tables 4 and 5.

(5) Measurement of 100% modulus (M100) Carbon fiber composite material samples and rubber composition samples (width 5 mm × length 50 mm × thickness 1 mm) of Examples 1 to 4 and Comparative Examples 1 to 5 were 10 mm / min. Elongation was performed, and the stress at the time of 100% deformation (M100: 100% modulus (MPa)) was determined. The measurement results are shown in Tables 4 and 5.

(6) Measurement of tear strength An angle-type test piece with no incision was punched from the carbon fiber composite material samples and rubber composition samples of Examples 1 to 4 and Comparative Examples 1 to 5 in accordance with JIS K 6252. A tear test was performed according to JIS K 6252 to measure the tear strength (N / mm). The results are shown in Tables 4 and 5.

(7) Chlorine resistance test A sodium hypochlorite aqueous solution having a chlorine concentration of 200 ppm and a pH of 9 ± 0.5 was prepared, and the carbon fiber composite material samples and rubber compositions of Examples 1-4 and Comparative Examples 1-5. The sample was immersed in the aqueous solution at 60 ° C for 1004 hours (changed to a freshly prepared aqueous solution every 24 hours, 5 times per week, excluding holidays), and the appearance change before and after immersion for 1004 hours was visually observed. While observing, the residual chlorine concentration in the aqueous solution after the lapse of 24 hours (after immersion for 1004 hours from the start of the test) of the aqueous solution adjusted at the time of 980 hours was measured. The results are shown in Tables 4 and 5. Moreover, the photograph of this aqueous solution after 1004 hours immersion is shown in FIG.

From Tables 4 and 5 and FIG. 6, according to Examples 1 to 4 of the present invention, the following was confirmed. That is, it was found that the carbon fiber composite material samples of Examples 1 to 4 of the present invention have high physical properties such as tensile strength and tear strength, and are excellent in chlorine resistance. Further, according to Comparative Examples 1 and 2, it was found that the rubber composition sample containing only SRF carbon black and MT carbon black as a reinforcing agent was excellent in chlorine resistance. However, the rubber compositions of Comparative Examples 1 and 2 were found to be inferior to the current product sample of Comparative Example 5 in physical properties such as tear strength.

It is a figure which shows typically the mixing process by a closed kneader. It is a figure which shows typically the 3rd kneading | mixing process (thinning) of the rubber composition by an open roll machine. It is a longitudinal cross-sectional view which shows schematic structure of the butterfly valve which is one Embodiment of piping equipment. FIG. 4 is a cross-sectional view taken along the line X-X ′ of FIG. 3 for explaining an opening / closing operation of a butterfly valve that is one embodiment of piping equipment. It is the graph which showed the mass change of the 2nd carbon nanofiber with respect to temperature by TG (thermal mass spectrometry) method. It is a photograph of the sodium hypochlorite aqueous solution after immersing the sample of an Example and a comparative example for 1004 hours.

Explanation of symbols

11 Sealed kneaders 12 and 14 First and second rotors 20 Butterfly valve 22 Seal member 24 Disc 30 Open rolls 32 and 34 First and second rolls 36 Mixture 200 Ethylene / propylene rubber 212 Carbon black 220 Second Carbon nanofiber

Claims (7)

Look-containing ethylene-propylene rubber, and carbon nanofibers surface oxidation treatment by heat treatment at 600 ° C. to 800 ° C. in an atmosphere containing oxygen, an average particle diameter of carbon black 50Nm～10myuemu, a,
The carbon nanofibers have a surface oxygen concentration of 2.6 atm% to 4.6 atm% measured by X-ray photoelectron spectroscopy (XPS), and an average diameter of 4 nm to 230 nm.
Carbon fiber having excellent chlorine resistance, in which 5 to 50 parts by mass of the carbon nanofibers and 10 to 120 parts by mass of the carbon black are blended with respect to 100 parts by mass of the ethylene / propylene rubber. Composite material.   In claim 1,
  The carbon nanofiber has an average diameter of 60 nm to 150 nm,
  The amount of the carbon nanofiber blended with respect to 100 parts by mass of the ethylene / propylene rubber is 10 to 40 parts by mass, and is a carbon fiber composite material excellent in chlorine resistance. A first carbon nanofiber having an average diameter of 4 nm to 250 nm manufactured by a vapor deposition method is subjected to an oxidation treatment by heat treatment at 600 ° C. to 800 ° C. in an oxygen-containing atmosphere . A first step of obtaining a carbon nanofiber of
A second step in which carbon black having an average particle size of 50 nm to 10 μm and the second carbon nanofiber are mixed in ethylene / propylene rubber and dispersed in the ethylene / propylene rubber by shearing force;
Only including,
The second carbon nanofiber has a surface oxygen concentration measured by X-ray photoelectron spectroscopy (XPS) of 2.6 atm% to 4.6 atm%,
In the second step, 5 to 50 parts by mass of the second carbon nanofiber and 10 to 120 parts by mass of the carbon black are blended with respect to 100 parts by mass of the ethylene / propylene rubber. The manufacturing method of the carbon fiber composite material excellent in chlorine resistance. In claim 3 ,
In the first step, the amount of increase in oxygen concentration on the surface of the second carbon nanofiber relative to the oxygen concentration on the surface of the first carbon nanofiber measured by X-ray photoelectron spectroscopy (XPS) is 0. The manufacturing method of the carbon fiber composite material excellent in chlorine resistance which oxidizes so that it may become 0.5atm%-2.6atm%. In claim 3 ,
In the first step, the increase rate of the oxygen concentration on the surface of the second carbon nanofibers relative to the oxygen concentration on the surface of the first carbon nanofibers measured by X-ray photoelectron spectroscopy (XPS) is 20 A method for producing a carbon fiber composite material excellent in chlorine resistance, wherein the oxidation treatment is performed so as to be in a range of from% to 120%. In any one of claims 3-5,
The first step is a method for producing a carbon fiber composite material having excellent chlorine resistance, wherein the mass of the first carbon nanofibers is reduced by 2% to 20% to obtain the second carbon nanofibers.   In any one of Claims 3-6,
  The second carbon nanofiber has an average diameter of 60 nm to 150 nm,
  The amount of the carbon nanofiber blended with respect to 100 parts by mass of the ethylene / propylene rubber is 10 to 40 parts by mass, and the method for producing a carbon fiber composite material having excellent chlorine resistance.