JP2000070836A - Water/oil-repellent coating film and its formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a water/oil-repellent coating film on the surface of a metal or glass. SOLUTION: A water/oil-repellent coating film forming method has a process for forming a thin graphite film 2 on the surface of a base material 1 by either one of a sputtering method, an ion plating method and a CVD method and a process for chemically bonding radical fluorine atoms generated by low temp,. plasma treatment using CF4 gas to carbon on the surface of the graphite film 2 to densely form CF3 groups 3 on the surface of the graphite film 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a product having a water-repellent or oil-repellent coating by surface treatment of glass, metal, ceramics or the like, and a method for forming the same.

[0002]

2. Description of the Related Art Strong water repellency and oil repellency are required for glass products such as vehicle windshields and optical lenses, ceramic products such as sanitary ware and tableware, and metal products such as molds in the lost wax method. There is.

[0003] For forming a water-repellent or oil-repellent film on these substrates, for example, the following methods are known. (1) Polytetrafluoroethylene (PTF)
E, Teflon) or a fluororesin paint or a silicone resin paint. When the water repellency of the coating film surface is represented by the contact angle of water, about 110 ° is obtained. This water repellency is P
CF ₂ group on TFE surface (surface energy 18 dyne / c
m) is due to the water repellency. (2) A paint in which PTFE fine particles having a particle diameter of about 4 μm fluorinated to the terminal are dispersed and mixed in vinylidene fluoride (PVdF) resin is applied to the surface of the base material (rust prevention control 39 (11))
P389 (1995)). Although about 145 ° to represent the water repellency of the coating film surface in the contact angle of water is obtained, the water repellent is obtained by the synergistic effect of the repellent aqueous and particulate unevenness of CF ₂ groups PTFE fine particle surface. Natural lotus leaves are the same as above, depending on the synergistic effect of water repellent substances secreted on the surface and projections on the surface. (3) Unevenness of about 0.1 μm is formed on the surface of a substrate such as a glass plate, and then, for example, CF ₃ (CF ₂ ) ₇ (CH
Tsubusuru immersion surfactants such as _{2) 2} SiCl ₃ in diluted to an organic solvent. A natural oxide film is formed on the surface of the substrate, and the surface of the oxide film contains a large number of hydroxyl groups, so a dehydrochlorination reaction occurs, and the fluorocarbon-based monomolecular film is formed on the surface of the substrate via siloxane bonds. (Japanese Unexamined Patent Publication No.
249146). The water repellency by this treatment is about 155 ° in terms of the contact angle of water, and the water repellency is determined by the CF ₃ group at the end of the monolayer (surface energy: 6 dyne / cm).
Is obtained by the synergistic effect of the water repellency and the shape of the unevenness, but the contact angle is reduced to 112 ° on a smooth surface without the unevenness, which is almost the same as that of the CF ₂ group of PTFE. (4) Fine powder of graphite fluoride, which is produced by directly reacting carbon fine powder with fluorine gas at 300 to 500 ° C., and a cationic surfactant are mixed, and plating is performed using a metal plate as a cathode and a Ni plate as an anode. There is an ultra-water-repellent surface with Ni plating and graphite fluoride fine powder adhered to the surface of the metal plate with stirring in a bath. Due to the synergistic effect of the water repellency of graphite fluoride and the irregularities due to the fine powder in the Ni plating, a water repellency close to the limit of a contact angle of 173 ° is obtained (Chemical 46 (7) P477 (1991)).

[0004]

The above-mentioned conventional water repellent and oil-in-oil coatings have the following problems. The following numbers correspond to the numbers described in the section of the related art. (1) Such a fluorine-based resin paint or silicone-based resin paint has a weak bonding force with a substrate surface due to its inherent water repellency or oiliness, and is inferior in weather resistance and friction resistance. ing. Further, the surface energy is not sufficiently low, and the contact angle of water is about 110 °, which is not sufficiently large. (2) The paint in which the PTFE fine particles are dispersed and mixed in the vinylidene fluoride resin can obtain a large water contact angle of 145 °, but the fine particles are deformed or detached during use, so that the water repellency is poor. The coating thickness is reduced to about 200
In some cases, the thickness as thick as μm may cause a problem. (3) In the case where minute irregularities are formed on the surface of the base material and a fluorocarbon monomolecular film is formed thereon, a large water contact angle of 155 ° can be obtained. It takes time and effort to form the irregularities, which increases the cost. (4) As described above, the fine powder of fluorocarbon is coated on the metal surface with Ni.
In the method of attaching with plating, the contact angle is 173 °
Although the contact angle of water can be obtained close to the limit, since plating is used, the substrate is limited to conductive metals and cannot be applied to glass and ceramics. There is a problem that the fine powder is easily separated and the water repellency is lowered.

The present invention has been devised in view of the above-mentioned problems of the prior art, and has been developed by forming a thin carbon film on the surface of a base material and forming CF ₃ groups at a high density on the surface. Highly water- and oil-repellent, high friction resistance, negligible dimensional change due to film formation, extremely thin, water-repellent, oil-repellent coating that does not lose light transmission when applied to translucent glass And a method for forming the same.

[0006]

According to the first aspect of the present invention, a water repellent or oil-repellent film is formed on a thin graphite film formed on a surface of a base material with a CF ₃ group at a high density. It is formed.

The substrate is preferably made of one of metal, glass and ceramics, and the graphite film has a thickness of 50 to 100.
It is preferably 0 nm.

The method for forming a water-repellent or oil-repellent oil film according to the third aspect of the present invention includes a sputtering method, an ion plating method, and a C method.
A step of forming a thin graphite film on the surface of the base material by any of the VD method, and chemically bonding radical fluorine atoms generated by low-temperature plasma treatment using CF ₄ gas with carbon on the surface of the graphite film, Forming a CF ₃ group densely.

Next, the operation of the present invention will be described. A graphite thin film is formed on a substrate surface. The base material is metal, glass or ceramics, and the thickness of carbon is 50 to 1000 nm. The graphite film is formed by a sputtering method, an ion plating method, or a CVD method. In the sputtering method, the pressure in the container is kept at 10 ⁻² to 10 ⁻³ Torr, and a carbon target is bombarded with an inert gas ion such as argon to emit carbon atoms, and the base material is arranged in the vicinity thereof. The released carbon atoms are attached to the substrate surface. In the ion plating method, as in the sputtering method, inert gas ions collide with a carbon target, and a DC voltage is applied between the target and the substrate to accelerate the released carbon ions and collide with the substrate. It is to adhere firmly to the substrate surface.

The CVD method includes a thermal CVD method and a plasma CVD method.
There is a law. The thermal CVD method heats the substrate to about 500 ° C,
When a CO gas pressurized to about 5 atm is sent, C is deposited by the following reaction by heating, and is deposited on the substrate surface. 2CO = C + CO ₂

In the plasma CVD, the inside of the container is 0.1 to 1 T
By maintaining a pressure of about orr and sending a hydrocarbon gas such as methane to cause glow discharge between the substrate and the electrode facing it, the hydrocarbons are separated into carbon and hydrogen, and the carbon is deposited on the surface of the substrate. It will adhere. In this case, the temperature of the substrate is room temperature.

Next, low-temperature plasma processing using CF ₄ gas is performed. The low-temperature plasma treatment is performed by setting the pressure of the container to 1 to 10 To.
This is to send a fluorocarbon (CF ₄ ) gas while maintaining the temperature at about rr to cause a glow discharge between the base material and the electrode facing the base material. In this case, the temperature of the substrate is room temperature. Radical fluorine atoms are generated from CF ₄ by the low-temperature plasma treatment, and the fluorine atoms are chemically bonded to carbon on the surface of the graphite film to form CF ₃ groups densely on the surface of the graphite film. The CF ₃ group has a surface energy of 6 d because fluorine is strongly bonded to carbon.
yne / cm and a water-repellent, oil-repellent film is obtained.
The contact angle of the obtained film with water is as large as about 145 °.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a structural view of a water-repellent and oil-repellent oil film of the present invention. In the figure, reference numeral 1 denotes a base material such as metal, glass or ceramic. Reference numeral 2 denotes a graphite film having a thickness of 50 to 1000 nm. Reference numeral 3 denotes a CF ₃ group which is densely formed on the surface of the graphite film 2. Numeral 4 is a water repellent and oily oil film. FIG. 2 is a drawing of water repellency and water droplets on the oil film. Numeral 5 denotes a water droplet, and θ denotes a contact angle between the water droplet, the water repellency, and the oil film 4. The surface energy of water is about 70 dyne / cm, the oil is about 30 dyne / cm, and the surface energy of CF ₃ group is about 6 dyne / cm.

Next, the operation of the present embodiment will be described. Substrate 1
A thin graphite film 2 is formed on the surface. The graphite film 2 can be formed by a method such as a sputtering method, an ion plating method, or a CVD method, and any of them may be used. After the graphite film 2 is formed, radical fluorine atoms generated by low-temperature plasma treatment using CF ₄ gas are chemically bonded to carbon on the surface of the graphite film 2 to form CF ₃ groups densely on the surface of the graphite film 2. Thereby, the water-repellent and oil-repellent oil film 4 is formed.

According to such a method, a thickness of 50 to 10
Several Angstroms on the surface of a 00 nm graphite (carbon) film
Ultra thin CF of order_Three Water-repellent, base oil with base membrane
4 is obtained. Thus, the coating of the graphite film 2 by fluorination
Then, fluoride fine particles CF _Two Monolayer of base and adsorption reagent
CF with low density_Three CF more densely than_Three Group
As it can be locked, there is no need to process the surface
In this case, 145 ° can be obtained in terms of the contact angle of water. In addition,
Water repellency and oil grease coated on the surface of the material
If a film is formed, stronger water repellency and oiliness can be obtained.
You.

[0016]

EXAMPLE A 15 mm × 15 mm × 2 mmt iron plate base material was degreased by ultrasonic cleaning in acetone, and then 30 ° C./min in a hydrogen atmosphere to remove oxides on the iron surface.
The temperature was raised to 500 ° C. with a temperature gradient of and kept for 10 minutes. While keeping the substrate temperature at 500 ° C., a CO gas of 5 atm was introduced, and carbon was deposited in a substrate shape by a thermal CVD method to form a graphite film on the substrate. The reaction time was set to 10 minutes, the mixture was naturally cooled, and the thickness of the graphite film was measured to be 500 nm.
Met. Next, this substrate was placed in a discharge tube, and CF ₄
Gas is flowed at a flow rate of 25 cm ³ / mim, and the pressure is 5 Torr.
r, and the substrate was used as a negative electrode, and a direct current glow discharge was performed between the substrate and a positive electrode facing each other at a distance of about 25 mm. Discharge current 10m
A, After the treatment for 5 minutes, the substrate was taken out of the discharge tube. A water drop was dropped on the substrate, and the contact angle between water and the substrate was measured. As a result, a contact angle of 145 ° was obtained.

The present invention is not limited to the embodiments and examples described above, and various changes can be made without departing from the gist of the invention.

[0018]

As described above, the water-repellent, oil-repellent film of the present invention is formed by forming CF ₃ groups at a high density on the surface of a thin graphite film formed on the surface of a substrate. Has excellent effects. (1) Since fluorine is chemically bonded to carbon atoms firmly bonded to the base material, there is no deformation or detachment of the water repellent or oil film. (2) Since it is an ultra-thin carbon film having a thickness of several tens to several hundreds of nm, a dimensional change due to the film thickness can be ignored as compared with coating or the like. (3) In particular, by setting the carbon film thickness on the order of several tens of nm, a decrease in light transmittance can be prevented, so that a light-transmitting glass having high water-repellent and oil-repellent effects can be obtained. (4) Since CF ₃ groups can be densely packed on the surface of the carbon film, the contact angle can be reduced to 14 without any surface unevenness processing.
5 degrees can be obtained, and the cost of the unevenness processing can be reduced.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a water-repellent and oil-repellent film of the present invention.

FIG. 2 is a drawing of water repellency and water droplets on the oil film.

[Explanation of symbols]

1 substrate 2 graphite film 3 CF ₃ group 4 water repellent, Hatsu oil film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C08G 85/00 C08G 85/00

Claims (3)

[Claims] 1. A water-repellent, oil-repellent film comprising a thin graphite film formed on the surface of a base material and a CF ₃ group formed at a high density on the surface thereof. 2. The water-repellent, oil-repellent film according to claim 1, wherein the substrate is any one of metal, glass and ceramics, and the thickness of the graphite film is 50 to 1000 nm. 3. A sputtering method, an ion plating method,
A step of forming a thin graphite film on the base material surface by any one of the CVD methods, and a method of chemically bonding radical fluorine atoms generated by low-temperature plasma treatment using CF ₄ gas with carbon on the graphite film surface to form a graphite film surface And a step of densely forming a CF ₃ group on the substrate.