JPH0215172A - Method of reforming base material surface - Google Patents

Abstract

PURPOSE:To form a thin compd. film of a fluorine-carbon bond which is uniform and secure and has an excellent adhesive property on the surface of a base material by bringing the gaseous plasma generated by electric discharge under a low pressure into contact with the base material in the presence of a gaseous mixture contg. a hydrocarbon compd. and fluorinated nitrogen compd. CONSTITUTION:The thin film having the fluorine-carbon bond is formed on the surface of the base material consisting of metals, ceramics, plastics, etc. The gaseous plasma generated by the electric discharge under the low pressure is brought into contact with the base material in the presence of the gaseous mixture composed of the hydrocarbon compd. and the fluorinated nitrogen compd. in this case. The plasma discharge is executed by a device having, for example, a carrier gas supplying path 1, a high-frequency power source 2, a plasma reaction system 3, a discharge electrode 4, and a discharge path 5. The thin compd. film of the fluorine-carbon bond which is uniform and secure and has the excellent adhesive property is formed on the surface of the base material in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to improving the surface of a substrate made of metals, metal oxides, ceramics, plastics, etc. by forming a thin film of a compound containing a fluorine-carbon bond on the substrate. Regarding modification methods.

Conventional technology and its problems A thin film of a fluorine-containing compound is formed on the surface of a base material made of metal, metal oxide, ceramics, plastics, etc. to improve chemical resistance, hydrophobicity, abrasion resistance, lubricity, etc. Methods for providing this are well known. Generally, wet coating of tetrafluoroethylene is widely used as such a method, but tetrafluoroethylene is expensive, and tetrafluoroethylene itself has a low surface area on materials such as metals and ceramics. Since it uses energy, it is difficult to form a film with excellent adhesion, and there is a problem that it peels off and flows out during use, reducing its functionality.

Research is also being conducted on methods of forming fluorocarbons on metal surfaces using chemical treatment methods in fluorine gas.
In addition to the danger of fluorine gas, the processing conditions are complex, making it unsuitable for practical use.

In addition, when metals, ceramics, etc. are directly treated with fluorine plasma gas, the metals and ceramics are
Since it contains only a trace amount of carbon, it is not possible to form a fluorocarbon compound. Especially when a metal is directly treated with a fluorine plasma gas, the surface of the metal becomes a fluoride metal and becomes hydrophilic and brittle. (It cannot fulfill its role of protecting the metal.

Means for Solving the Problems The present inventor formed a strong thin film of a compound having a fluorine-carbon bond on the surface of metals, ceramics, plastics, etc. to improve hydrophobicity, lubricity, abrasion resistance, and As a result of intensive research with the aim of imparting chemical properties, we have found that plasma gas generated by discharging a gas mixture containing hydrocarbon compounds and fluorinated nitrogen compounds can be applied to metals, ceramics, plastics, etc. It has been found that a thin film of a compound having a fluorine-carbon bond can be uniformly and firmly formed on a substrate by contacting the fluorine-carbon bond with the substrate. The present invention is based on such knowledge.

That is, the present invention provides a method for modifying the surface of a substrate, which comprises bringing plasma gas generated by discharge under low pressure into contact with the substrate in the presence of a mixed gas containing a hydrocarbon compound and a nitrogen fluoride compound. Pertains to.

In the present invention, in the presence of a mixed gas containing a hydrocarbon compound and a fluorinated nitrogen compound, a thin film of a compound having a fluorine-carbon bond is formed on a substrate by bringing plasma gas generated by discharge into direct contact with the gaseous material. can be done. Hydrocarbon compounds that can be used in the method of the present invention include, for example, CH4, C2H4, C9H
6, C3H8, C4H, 0, C6H6, etc. can be exemplified.

As the fluorinated nitrogen compound, any fluorinated nitrogen compound that is gaseous at room temperature or gasified at the temperature during discharge treatment can be used; for example, NF3 or the like may be used. These may be used alone or in combination. The mixing ratio of the hydrocarbon compound and the nitrogen fluoride compound and the processing conditions may be determined as appropriate depending on the required properties of the thin film.

If necessary, gases such as N2 and He can be added to this mixed gas to adjust the discharge voltage, etc.
Further, hydrogen, oxygen, etc. may be mixed in order to improve the performance of the formed film, the bonding performance with the base material, etc.

The method of the present invention is advantageous in terms of safety because it does not use fluorine molecular gas, which is dangerous to handle and is used as a fluorine raw material in the production of fluorinated graphite by the conventional discharge plasma method.

The plasma generation methods used in the present invention include: ■ DC glow discharge or low frequency discharge using an internal electrode method; ■ High frequency discharge using an internal electrode method, external electrode method or coil type method; ■ Microwave discharge using a waveguide type method. , ■ Electron cyclotron resonance discharge (ECR discharge) ■ Induction coil type high-frequency discharge that does not use electrodes, etc., but is not limited to these, and any method that can generate plasma by discharge may be used. .

As a treatment condition, for example, the total pressure of the mixed gas is 100 to 10
-3 torr, flow rate of about 0.1 to 500 mu/min (N, T, P, ), discharge power of 10 to 300 W
It is sufficient to discharge at a certain level. When using a large-scale device, processing can be performed in a manner exceeding this amount and using more power. The ratio of hydrocarbon compounds to fluorinated nitrogen compounds is
The number of C in the hydrocarbon compound and the number of F in the fluorinated nitrogen compound may be set to about 0.01≦C/F≦5. The substrate may be at room temperature or heated.

In the present invention, the base material is not particularly limited, but for example, metals, metal oxides, ceramics, plastics, etc. can be used. The types of these base materials are not particularly limited, but examples of metals include copper, iron,
Nickel, aluminum, chromium, tungsten, tin,
Examples include all metals including zinc, silicon, manganese, titanium, indium, etc., and alloys thereof.

Examples of the metal oxide include oxides of the above metals.

Ceramics include glasses such as silicate glass, quartz glass, borate glass, and phosphate glass;
Examples include cements such as alumina cement, portland cement, and magnear cement, magnesia, zircon, alumina, titanium oxide, silicon carbide, and silicon nitride.

There are no particular restrictions on plastics, and a wide variety of materials can be used, such as polyethylene resin, polypropylene resin, polyacetal resin, acrylic resin, nylon resin, cellulose resin, polycarbonate resin, phenoxy resin, polyester resin, polyurethane resin, diallyl resin, etc. Examples include phthalate resins, phenol formaldehyde resins, urea resins, melamine aldehyde resins, epoxy resins, furan resins, xylene resins, silicone resins, polystyrene resins, vinyl resins, alkyd resins, and chlorinated polyether resins.

The shape of the base material is not particularly limited, and can be any shape such as a round rod shape, a prismatic shape, or a plate shape.

In the present invention, the position of the base material placed in the discharge device may be within the electric field that generates plasma, or outside the electric field as long as it is within the range that the gas passing through the plasma of the fluorine-containing compound reaches in an active state. It may be. Particularly when using plastic as a base material, for example, if the base material is subjected to microwave discharge in an electric field, the plastic may melt. It is necessary to place the base material outside the electric field and within the reach of the active gas that has passed through the plasma.

Furthermore, when a substrate is placed in an electric field and discharged, a thin film of a compound having fluorocarbon bonds may be formed while the surface of the substrate is etched. It will be necessary to determine the processing conditions.

The preferred thickness of the thin film of a compound having a fluorine-carbon bond is not particularly limited as it varies depending on the purpose;
Usually, the purpose of modifying the surface of the base material can be achieved with a thickness of about 0.01 to 10 μm.

Depending on the method of the present invention, the type of sample gas, mixing ratio, pressure,
The degree of fluorination of the carbon-containing film is controlled by adjusting various conditions such as the discharge method, such as alternating current, direct current, or high frequency, discharge time, distance between electrodes, substrate temperature, and repetition of ON and OFF discharges. It is possible to adjust the hydrophobic performance etc. of the surface of the base material. The degree of fluorination can be quantitatively measured by the F/C ratio calculated by X-ray photoelectron spectrum (ESCA spectrum) analysis.

Effects of the Invention According to the method of the present invention, a uniform and strong thin film of a compound having a fluorine-carbon bond with excellent adhesion can be formed on the surface of a substrate regardless of the type of specimen. Also,
The method of the present invention is a method with excellent safety because it does not use fluorine molecular gas as a fluorine raw material. Furthermore, the method of the present invention has the great advantage that the target product can be obtained in an extremely short time compared to chemical treatment methods.

Furthermore, with the method of the present invention, it is possible to form a thin film of a compound having a fluorine-carbon bond that is more hydrophobic than polytetrafluoroethylene, and the substrate treated with the method of the present invention has chemical resistance. It has excellent properties such as hardness, hydrophobicity, wear resistance, and lubricity.

Substrates treated by the method of the present invention are useful for, for example, magnetic tapes, moisture-proof films for precision machines, artificial blood vessels, blood bags, etc. in the case of plastics, and artificial bones, roof tiles, etc. in the case of ceramics. It can be effectively used as
Metals have a wide range of uses, such as being used as materials for machines used in liquids, sliding materials, etc.

Example Hereinafter, the present invention will be described in detail with reference to Examples.

Note that the gas flow rate in the examples is a value measured under atmospheric pressure.

Example 1 A plasma discharge device using high frequency discharge shown in FIG. 1 was used as a plasma discharge device. The plasma discharge apparatus shown in FIG. 1 includes a raw material, a carrier gas supply path 1, a high frequency power source 2
, a plasma reaction system 3, a discharge electrode 4, and an exhaust path 5.

A 5US304 stainless steel thin plate pretreated for 5 minutes by sputtering in 0.5 Torr Ar gas was used as a sample.
The sample was placed on the discharge electrode of the plasma discharge device, and after sufficiently exhausting and reducing the pressure inside the discharge electrode, 15 m of CH, -NF3 mixed gas (molar ratio 7:13) with a total pressure of 0.2 Torr was poured into the discharge electrode.
30W, 13.56M while flowing at a flow rate of Q/min.
Plasma was generated by applying Hz high frequency power (radio waves) to the electrodes, and discharge was performed for 3 minutes. As a result of this treatment, the sample surface was significantly hydrophobicized, and the contact angle of water increased from 0 degrees to approximately 90 degrees.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a plasma discharge device used in Example 1. In the figure, (1) is the raw material, carrier gas supply path, (2
) is a high frequency power source, (3) is a plasma reaction system, (4) is a discharge electrode, and (5) is an exhaust path. (hereinafter '2)

Claims (1)

[Claims] (1) A method for modifying the surface of a substrate, which comprises bringing plasma gas generated by discharging under low pressure into contact with the substrate in the presence of a mixed gas containing a hydrogen compound and a nitrogen fluoride compound.