JPH06305858A - Method for modifying surface of carbon material - Google Patents

Abstract

PURPOSE:To enable modification of the surfaces of carbon materials of various kinds by a simple process under a mild condition without requiring a specific device by bringing fluorine gas into contact with the surface of a carbon material and then bringing a prescribed monomer to the surface of the carbon material. CONSTITUTION:0.1-50% fluorine gas diluted with an inert gas such as nitrogen or helium is brought into contact with the surface of a carbon material under 1Torr to 2 atmospheric pressure at -70 to 200 deg.C for 1 second to 10 days, then one or more monomers having Alfrey-Price's (e) value of 1.7>(e)>-1.0 handleable in a gaseous state is brought into contact with the surface of the carbon material to cause polymerization reaction on the surface of the carbon material to form a polymer film having several Angstrom to several 100 micron thickness. Optionally, various gases are brought into contact with the end of the polymer to stop the polymerization or further another monomer is brought into contact with the surface of the carbon material and a different polymer layer is formed to give a carbon material having a modified surface of high water repellency and maintaining surface characteristics of >=100 deg. contact angle with water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying a surface of a carbon material and a novel carbon material produced by the method, and more specifically, a synthetic resin for coating the surface of the carbon material with a polymer having a functional group. The present invention relates to a method for modifying the surface and a novel carbon material exhibiting unprecedentedly large water repellency. The method for modifying the surface of a carbon material of the present invention is to introduce a fluorine-containing, oxygen-containing or nitrogen-containing functional group or various functional groups obtained via the functional group into the surface of the carbon material to obtain water / oil repellent performance. , Sliding performance, hydrophilic
It is useful as a method for imparting a new function to the surface of the carbon material such as lipophilicity, chemical resistance, heat resistance, electric conductivity, and electric insulation.

[0002]

2. Description of the Related Art As a method for forming a polymer on the surface of a carbon material, a coating method by coating, a physical modification method using physical energy such as plasma treatment, γ-
There is known a chemical modification method in which radicals are formed by irradiation with radiation such as rays or light to generate graft chains.

[0003]

However, since the plasma processing method requires vacuum conditions, it is difficult to continuously process a large-sized material, and further, it is unsuitable as a general-purpose processing method which requires high equipment cost and is simple. . In the coating method by coating, it is difficult to obtain sufficient adhesiveness, it is difficult to form a thin film, and cleaning and drying steps are required due to wet processing, and the process is complicated.

Furthermore, it is difficult to uniformly irradiate the surface of the carbon substrate having various shapes with the method using radiation or light, and the cost of the apparatus is high. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wide range of types of carbon material surface by a simple process that does not require a special device, and by the action of mild conditions. Another object of the present invention is to provide a method for modifying the surface of a carbon material, which is capable of coating a polymer having various functional groups with a uniform film thickness.

[0005]

That is, the gist of the present invention is that after the fluorine gas is brought into contact with the carbon material surface, the Alfrey-price e value, which is a measure of the reactivity of the monomer, is 1.7> e. A method of modifying a surface of a carbon material is characterized in that a new polymer layer is formed on the surface of the carbon material by contacting a monomer having a ratio of> -1.0.

The present invention will be described in detail below. As the carbon material to which the present invention can be applied, those having a hydrocarbon moiety capable of reacting with fluorine gas are preferable, but those subjected to a surface treatment such as oxidation treatment may be used, and the following are exemplified. . (1) Carbon fibers (pitch-based, PAN-based, rayon-based, etc.) (2) Pitches (isotropic, anisotropic pitch, etc.) (3) Carbon black, activated carbon, C60, etc. (4) Graphite (isotropic) Properties, anisotropy) (5) Glassy carbon, etc. The form of the carbon material can be arbitrarily selected such as a film, a plate, a powder, a fiber or a molded body (tubes, containers, etc.).

In the present invention, first, fluorine gas is brought into contact with the surface of the carbon material. The effect of contacting the surface of the carbon material with the fluorine gas in advance is that the reaction between the carbon material and the fluorine gas forms a radical-like reaction active site for initiating the polymerization reaction of the monomer described later. Therefore, the conditions under which the fluorine gas is brought into contact may be conditions greatly relaxed as compared with the case of the direct fluorination reaction treatment.

Fluorine gas may be diluted with an inert gas such as nitrogen or helium, and the concentration thereof is not particularly limited, but is in the range of 0.1 to 50%, preferably 1 to 50%.
It is selected from the range of 20%. The fluorine gas concentration is
It is possible to prevent the direct fluorination reaction from proceeding preferentially,
Moreover, it is safe to handle. The contact pressure of the fluorine gas can be any condition from reduced pressure to increased pressure.
The pressure is usually selected from the range of 1 torr to 2 atm, though it depends on the concentration of the fluorine gas used.

The contact temperature of the fluorine gas is selected such that the direct fluorination reaction does not proceed preferentially, but the range is usually -70 to 200 ° C, preferably -70 to 90.
C., most preferably 0 to 80.degree. The contact time of the fluorine gas is appropriately selected from a wide range and is usually
It is carried out for 1 second to 10 days, preferably 1 minute to 3 hours.

[0010] It should be noted that the conditions can be appropriately selected outside these ranges if it is considered practicable by those skilled in the art. Next, the Alfrey-price e value, which is a measure of the reactivity of the monomer on the surface of the carbon material in contact with fluorine gas, is 1.7>e> -1.
The monomer which is 0 is contacted. Due to the action of such a monomer, a polymerization reaction occurs on the surface of the carbon material to form a polymer film.

The monomer that can be handled in a gas state is preferable. As the monomer used in the present invention,
An Alfrey-Price e value defined as 1.7>e> -1.0, which is a measure of the reactivity of the monomer, is used. Examples of the monomer having an e value defined as 1.7>e> −1.0 are shown in, for example, “Polymer Data Handbook” (Baifukan, 1986),
The following monomers may be mentioned.

(1) Olefins acenaphthylene, sodium ethylenesulfonate, butyl ethylenesulfonate, p-oxathiene, N- (2-
(Chloroethyl) ethylenesulfonamide, chlorotrifluoroethylene, 2-chloro-1-propylene, 3-chloro-1-propylene, cyclopentene-1,3-dione, 2-vinylnaphthalene, 1,3-butadiene-1-
Carboxylic acid, 1,3-butadiene-1-carboxylic acid 2,
3-epoxypropyl, tert-butyl isopropenyl ketone, propylene, hexachloro-1,3-butadiene, 1-hexene, etc.

(2) Fluorine-containing olefin tetrafluoroethylene, hexafluoropropylene,
Vinylidene fluoride, vinyl fluoride, 3,3,3-trifluoropropylene, 1,3,3,3-tetrafluoropropylene, octafluoroisobutylene, hexafluoro-1,3-butadiene, chlorotrifluoroethylene, etc.

(3) Styrene and its derivatives p-acetoxystyrene, p-acetyl-α-methylstyrene, α-acetoxystyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-chloromethylstyrene, p-cyanostyrene, β, β-difluorostyrene, α- (difluoromethyl) styrene, 2,4-dibromostyrene, butyl styrenesulfonate, cis-stilbene, trans-stilbene, p-
Nitrostyrene, p-phenylstyrene, p-fluorostyrene, β-fluorostyrene, p-tert-butylstyrene, p-bromostyrene, p-benzoylstyrene, 2,3,4,6-chlorostyrene, 2,3,3. 4,
5,6-pentafluorostyrene, p-iodostyrene, etc.

(4) Vinyl halides Vinylidene chloride, vinyl chloride, vinyl bromide, vinyl iodide, etc. (5) Vinyl esters Vinyl benzoate, vinyl isocyanate, p-isocyanate
-Vinylphenyl, vinyl isothiocyanate, vinyl formate, vinyl p-chlorobenzoate, vinyl chloroacetate, vinyl cinnamate, vinyl acetate, vinyl p-cyanobenzoate, ethyl vinyl oxalate, vinyl dichloroacetate, divinyl carbonate, vinyl trichloroacetate. , Trifluorovinyl acetate, p-vinylbenzoic acid, p-vinylbenzoic acid chloride, vinyl propionate, vinyl pentafluoroacetate,
α-Methoxybenzoate etc.

(6) Vinyl pyridines 2-isopropenyl pyridine, 2-vinyl pyridine, 4
-Vinyl pyridine, 2-vinyl pyridine oxide, etc.

(7) Acrylic acid derivative Acrylamide, isopropyl acrylate, ethyl acrylate, 2,3-epoxypropyl acrylate, octadecyl acrylate, p-cresyl acrylate, chloride chloride, 2-chloroethyl acrylate, acrylic acid p-chlorophenyl, cyclododecyl acrylate, 6,8-dimethyl-4-oxochromanimethyl acrylate,
2,4,6-Trichlorophenyl acrylate, sodium acrylate, 2-nitrobutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, phenyl acrylate, ferrocenylmethyl acrylate, butyl acrylate, P-Bromophenyl acrylate, propyl acrylate, benzyl acrylate, methyl acrylate, 1-acryloylaziridine, N-acryloylpyrrolidone, 1-acryloyl-2-benzoylhydrazine, acrylonitrile, acrolein, α-
Ethyl acetoxy acrylate, α-acetoxy acrylonitrile, α-ethyl methyl acrylate, β-ethoxy acrylate, N-octyl acrylamide, α-
Methyl chloroacrylate, α-chloroacrylonitrile, α-chloroacrolein, 3- (2-chloroethyl) -6-acroyloxypyridazinone, methyl α-cyanoacrylate, N, N-dibutylacrylamide,
N, N-dimethyl acrylamide, methyl thioacrylate, N- (hydroxymethyl) acrylamide, α-fluoromethyl acrylate, ethyl α-fluoromethyl acrylate, acrylic anhydride, α-methoxyacrylonitrile, etc.

(8) Methacrylic acid derivative 1,2-dimethacryloyloxyethane, N-phenylmethacrylamide, methacrylic anhydride, methacrylamide, methacrylic acid, zinc methacrylate, methacrylic acid 2
-Acetoxyethyl, isopropyl methacrylate, ethyl methacrylate, 2,3-epoxypropyl methacrylate, octafluoropentyl methacrylate, chloride chloride, 2-chloroethyl methacrylate, chloromethyl methacrylate, dodecyl methacrylate, 2-methacrylate Nitropropyl, cyclohexyl methacrylate,
Phenyl methacrylate, furfuryl methacrylate, fluoride fluoride, propyl methacrylate, benzyl methacrylate, methyl methacrylate, methacrylonitrile, methacrolein, N-methylmethacrylamide, etc.

(9) Dienes 2-acetoxy-3-methyl-1,3-butadiene, butadiene, isoprene, chloroprene, etc.

(10) Others Methyl atropate, atroponitrile, N-allylacetamide, allyl alcohol, 2-allylpyrrole, allylphenyl ether, allylbenzene, N-allylbenzamide, isopropyl vinyl ketone, isopropenyl phenyl ketone, Isopropenyl methyl ketone, itaconic acid, diethyl itaconate, ethyl isopropenyl ketone, ethyl vinyl ketone, ethyl vinyl sulfide,
Ethyl vinyl sulfoxide, octadecyl vinyl ether, crotonaldehyde, methyl crotonate, crotonnitrile, N- (2-chloroethyl) itaconimide,
p-Methyl chlorocinnamate, allyl chloroacetate, chloroprene, chloromethyl vinyl ketone, phenyl cinnamate, tert-butyl cinnamate, benzyl cinnamate, methyl arsenate, isopropenyl acetate, cinnamonitrile, diphenylvinylphosphine, diphenylvinylphosphine. Oxide, methyl sorbate, sorbonitrile, vinylene carbonate, triethoxyvinylsilane, tributylvinyltin, trimethylvinylgermane, trimethylvinylsilane, trimethyl (p-vinylphenyl) silane, 5-vinylisoxazole, 1-vinylimidazole, 2-vinyl Thiophene, 2-vinylphenanthrene, m-vinylphenol, p-vinylbenzenesulfonamide, p-vinylbenzamide, diethyl vinylphosphate, phenylvinyl Ton, phenyl vinyl sulfone, α-phenyl vinyl phosphoric acid, diallyl phthalate, diethyl fumarate, diisopropyl fumarate, pentafluorophenyl vinyl sulfide, muconic acid, diethyl muconate, dicyclohexyl mesaconate, diphenyl mesaconate, dimethyl mesaconate, Methyl vinyl sulfone,
2-methylene glutarate diethyl etc.

Usually, when the Alfrey-price e value showing the polymerization reactivity of the monomer is 1.7>e> -1.0,
It is said that radical polymerization is easy, while e> 1.7.
It is considered that the monomer (1) is easily anionically polymerized.
Therefore, it is considered that the above-mentioned monomer has a high reactivity with the activated site formed by the action of the fluorine gas, and a polymerized film is satisfactorily formed. Among these monomers, tetrafluoroethylene, acrylic acid, methyl acrylate, acrylonitrile, etc., in which the value of e is relatively large, are particularly preferable.

These monomers may be used alone or in a combination of two or more. The contact pressure of the monomer having various functional units can be any condition from reduced pressure to increased pressure, and normally, the range of 1 torr to 10 atm is selected. In order to industrially advantageously carry out the method of the present invention in consideration of the reactor, productivity, etc., and to avoid the risk of explosion, the range of 0.5 to 2 atm is preferable.

The contact temperature of the monomer varies depending on the monomer used, but is usually 0 to 200 ° C., preferably 2
It is selected from the range of 0 to 90 ° C. The contact time of the monomer is appropriately selected from a wide range and is usually 1 second to 10 days,
It is preferably in the range of 1 minute to 5 hours. Even outside these ranges, the conditions can be appropriately selected when it is considered practicable by those skilled in the art.

In the present invention, after the polymerization reaction, the polymerization can be terminated by bringing the polymerization terminals into contact with various gases. The reaction conditions at that time can be the same as the above-mentioned fluorine gas action conditions, and it is also possible to form different polymer layers by using other monomer gas. The film thickness of the polymer having a functional unit to be formed can be controlled by factors such as the pressure of the monomer to be acted, the temperature, and the action time, but a polymer layer of several angstroms to several hundreds of microns can be usually formed.

The surface-modified carbon material according to the present invention has extremely excellent water repellency, and specifically,
It is possible to maintain the surface performance in which the contact angle with water (water droplet contact angle) is 100 ° or more. As described above, the method for modifying a carbon material according to the present invention is carried out under mild conditions. That is, it is sufficient that the fluorine gas contact condition is a mild condition in which all of the concentration, temperature and time are greatly relaxed, and the monomer gas contact condition does not need to pressurize. Further, according to the present invention, there are the following advantages (1) to (3) by adopting mild conditions.

(1) Since it is not necessary to use highly dangerous fluorine gas of high concentration, operational safety can be obtained. (2) Surface modification is possible even at a low temperature of 100 ° C. or lower. (3) Since it is possible to adopt a pressure condition at room temperature or lower, it is possible to use tetrafluoroethylene gas or the like, which may explode under pressure, under safe conditions. Avoiding pressurization conditions is also advantageous from the viewpoint of reactor and productivity.

[0027]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless it exceeds the gist.

Example 1 A carbon fiber sample calcined at 2500 ° C. was placed in a reactor having resistance to fluorine, and after evacuation, fluorine gas diluted to 5% with nitrogen was introduced to 210 torr. After standing at room temperature for 20 minutes, the fluorine gas was evacuated and then tetrafluoroethylene gas was introduced to adjust the pressure to 760 torr. The temperature was raised at 2 ° C./min, the mixture was allowed to stand at 80 ° C. for 1 hour, then returned to room temperature, and unreacted tetrafluoroethylene gas was replaced with nitrogen gas. After evacuation of the nitrogen gas again, in order to replace the fluorine at the polymerization end, fluorine gas diluted with nitrogen to 5% was introduced to 100 torr and left standing for 5 minutes. Finally, after replacing the fluorine gas with nitrogen, the sample was taken out and the film formed on the surface was analyzed.

It was also confirmed by SEM observation that the contact angle to water by the Wilhelmy method was θ110 ° and the water-repellent film was formed on the sample surface (θ = 97 °). As a result of XPS analysis, a peak (292 eV) attributed to (CF ₂ ) _n was observed, and thus the formed water-repellent film has a polytetrafluoroethylene structure and its film thickness is 50 Å or more. Was confirmed

Example 2 A carbon fiber sample calcined at 2500 ° C. was placed in a reactor having resistance to fluorine, and after evacuation, a fluorine gas diluted with nitrogen to 10% was introduced to 210 torr. After standing at room temperature for 20 minutes, the fluorine gas was evacuated, and then
Mixed gas of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) (TFE / HFP = 36
0/400 torr) was introduced to make 760 torr.
The temperature was raised at 2 ° C./min, the mixture was allowed to stand at 80 ° C. for 1 hour, then returned to room temperature, and the unreacted mixed gas was replaced with nitrogen gas. After evacuation of the nitrogen gas again, a fluorine gas diluted with nitrogen to 10% in order to replace the polymerization terminal with fluorine was introduced to 100 torr and left standing for 5 minutes. Finally, after replacing the fluorine gas with nitrogen, the sample was taken out and the film formed on the surface was analyzed.

The contact angle θ with water according to the Wilhelmy method was 110 °, and it was confirmed by SEM observation that the water-repellent film was formed on the sample surface (θ = 97 °). As a result of XPS analysis, a peak (292 eV) assigned to (CF ₂ ) _n and a peak (293 assigned to CF ₃ )
eV) was observed, and HFP / TFE =
It was confirmed that a 0.16 copolymer film was formed.

Example 3 A carbon fiber sample calcined at 1500 ° C. was placed in a reactor having resistance to fluorine, and after evacuation, a fluorine gas diluted with nitrogen to 10% was introduced to 120 torr. After standing at room temperature for 20 minutes, the fluorine gas was evacuated, and then
Acrylonitrile gas was introduced at 140 torr, and nitrogen gas was added to adjust to 1 atm. After standing at room temperature for 1 hour, unreacted acrylonitrile gas was replaced with nitrogen gas, a sample was taken out, and the film formed on the surface was analyzed. The contact angle θ with water according to the Wilhelmy method was 75 °, and an acrylonitrile film was formed on the sample surface (θ = 96 °). As a result of XPS analysis, since a peak (401 eV) attributed to —CN was observed, it was confirmed that the formed film had an acrylonitrile structure and the film thickness was 50 Å or more.

Comparative Example 1 A carbon fiber sample calcined at 2500 ° C. was put in a reactor having resistance to fluorine, evacuated and then tetrafluoroethylene gas was introduced to 760 torr. 1 at 80 ° C
After standing for a while, the temperature was returned to room temperature and the unreacted tetrafluoroethylene gas was replaced with nitrogen gas. After evacuating the nitrogen gas again, use nitrogen to replace the polymerization end with fluorine.
Fluorine gas diluted to 0% was introduced to 100 torr, and the mixture was allowed to stand for 5 minutes. Finally, after replacing the fluorine gas with nitrogen, the sample was taken out and the carbon fiber surface was analyzed. The contact angle θ with water by the Wilhelmy method was 84 °, and it was confirmed that the water-repellent film was not formed on the sample surface (θ = 97 °).

Comparative Example 2 A carbon fiber sample calcined at 1500 ° C. was placed in a reactor, evacuated, and then acrylonitrile gas was introduced at 140 torr. Furthermore, after adding nitrogen gas to 760 torr,
It was left to stand at room temperature for 1 hour. After the unreacted acrylonitrile gas was replaced with nitrogen, a sample was taken out and the carbon fiber surface was analyzed. The contact angle θ with water by the Wilhelmy method was 97 °, and as a result of XPS analysis, a peak derived from nitrogen was not observed. Therefore, it was confirmed that the acrylonitrile film was not formed on the sample surface.

[0035]

EFFECTS OF THE INVENTION According to the present invention, a wide variety of types of carbon material surfaces are coated with a uniform functional-containing polymer film having an arbitrary thickness by a simple process without requiring a special apparatus and a large amount of energy. It is also possible to make a multi-layer structure by using several kinds of monomers, and its industrial significance is great.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location D06M 11/07 14/36 // D06M 101: 40 (72) Inventor Nao Imaki Yokohama City, Kanagawa Prefecture 1000, Kamoshida-cho, Midori-ku Sanryo Kasei Co., Ltd.

Claims (2)

[Claims] 1. An Alfrey-price e value of 1.7>e>-after a fluorine gas is brought into contact with the surface of a carbon material.
A method for modifying a surface of a carbon material, which comprises contacting a monomer of 1.0 to form a new polymer layer on the surface of the carbon material. 2. A novel carbon material having a surface water drop contact angle of 100 ° or more.