JPH02254150A - Surface treatment - Google Patents

Abstract

PURPOSE:To form hydrophilic films having excellent durability on the surface of substrates by placing various kinds of base materials into a vacuum reaction chamber and generating plasma by electrodes provided on both sides thereof to reform the surface of the base materials, then subjecting various kinds of inorg. oxides to vapor deposition by an electron beam. CONSTITUTION:The inside of the reaction chamber 1 is evacuated to a vacuum and the base material 4 of a film shape, sheet shape, etc., mounted to a rotary holder 3 is placed between two pieces of the electrodes 2 and 2 and gas, such as oxygen or ozone, is introduced from a gas introducing port 10 into the chamber. Plasma is discharged between the electrodes 2 and 2 by a power source 5 to treat the surface of the base material 4. The inorg. oxides, such as SiO2, Al2O3, TiO2, MoO3, WC, ZrO2, SnO2, and glass, put into a boat 7 are irradiated with the electron beam 8 and are thereby evaporated so that the thin films thereof are formed on the surface of the base material 4. The hydrophilic films having the excellent durability are thus formed. The surface of the base material 4 may be reformed by irradiating the same with UV rays in this method.

Description

Detailed Description of the Invention d. Industrial Application Field The present invention relates to a method for treating the surface of various substrates, and more specifically, the surface of the substrate of a film, sheet, fibrous material, or various molded products is treated to improve durability. The present invention relates to a method for forming an excellent hydrophilic coating.

b. Conventional Technology Many surface treatment methods have been proposed in the past, in which a hydrophilic film is formed on the surface of a substrate to impart antistatic and antifogging properties, and furthermore to prevent the adsorption of dirt. For example, a method of forming a hydrophilic plasma polymerized film or an inorganic oxide film on the surface of a substrate,
There are methods of oxidizing the surface of the base material by physical or chemical treatment methods, and methods of exciting the surface of the base material with radiation, plasma, light irradiation, etc. and then forming a hydrophilic resin film.

C1 Problems to be Solved by the Invention However, the surface treatment method described above has a problem in that even if the initial hydrophilicity is good, the hydrophilicity deteriorates during repeated use.

For example, in order to wear contact lenses without discomfort, there is a method of making the surface hydrophilic by gas plasma treatment with a non-polymerizable gas such as oxygen or nitrogen or acid treatment.

However, the effects of these methods are temporary and have the disadvantage that the treatment effect is lost even if the contact lens is left in the air for a while.

Another method is to form a hydrophilic plasma polymerized film or an inorganic oxide film such as silicon oxide or aluminum oxide on the surface of the contact lens by vacuum deposition, ion blating, etc. to make the surface hydrophilic. However, this method has the disadvantage that the plasma polymerized film or inorganic oxide thin film peels off during repeated use because the adhesion between the contact lens and the plasma polymerized film or inorganic oxide film is not sufficient. There is.

Another method is to make the surface hydrophilic by exciting the contact lens surface with non-polymerizable gas plasma or the like and then polymerizing a hydrophilic monomer on the surface. However, this method has the disadvantage that since the hydrophilic layer on the surface is soft, the hydrophilic layer gradually wears out with repeated washing.

Further, in JP-A-56-147829, as shown in FIG.
A method for forming a hard coating that forms the inorganic composite film 22 is disclosed. According to this method, a hard coating having excellent durability can be formed on the surface of a plastic substrate.

However, this method has a problem in that since the adhesion of the organic polymer layer to the plastic substrate is not good, the adhesion of the inorganic hard coating to the plastic substrate also decreases.

d. Means for solving the problem, that is, the present invention, modifies the surface of the base material by irradiating the surface of the base material with ultraviolet rays in the presence of oxygen and/or ozone, or by treating it with non-polymerizable gas plasma. A surface treatment method characterized by forming an inorganic oxide thin film on the surface of the substrate (hereinafter referred to as [method (1)]) and applying oxygen and/or A method for surface treatment of molded products characterized by plasma treatment while irradiating ultraviolet rays in the presence of ozone (hereinafter referred to as [Method (2))]
).

First, in method (1), for the ultraviolet treatment, the ultraviolet lamp may be a low-pressure mercury lamp having a wavelength range of 1600 to 4000 angstroms, a xenon lamp, a metal halide lamp, a carbon arc lamp, or a JP-A-58121 lamp.
A deuterium lamp such as that disclosed in No. 28 can be used. In particular, in the present invention, 1650 to 20
Preferably, a lamp is used that generates two wavelengths of ultraviolet radiation: 50 angstroms and 2350-2750 angstroms. The amount of ultraviolet rays emitted from these lamps should be 0.01 J/cJ or more, especially 0.01 J/cJ or more.
1 to 5 J/cfI is preferred. Here, when irradiating ultraviolet rays in the presence of oxygen and/or ozone, the oxygen concentration is 1% by volume or more, preferably 10 to 1.00% by volume, and the ozone concentration is 0.01% by volume or more, preferably 0.5～
Preferably it is 10% by volume. Here, if the amount of ultraviolet ray irradiation is small and the concentration of oxygen and ozone is low, it is difficult to fully exhibit the effects of the present invention.

In addition, the ultraviolet irradiation time is usually 1 to 120 minutes, preferably 5 to 60 minutes, and when the irradiation time is long, the irradiation is performed intermittently, for example, by irradiating for 5 minutes and then turning off for 5 minutes. By employing this method, it is possible to prevent the substrate, which is the object to be treated, from deteriorating due to light or heat.

In addition, the temperature near the base material during irradiation is usually 5 to 200°
C1 is preferably 15 to 00°C.

Examples of the non-polymerizable gas used in the plasma in method (1) of the present invention include air, oxygen, nitrogen, ammonia, etc., and two or more of these gases may be used as a mixture.

In the method (]) of the present invention, the plasma treatment conditions are as follows:
The conditions are the same as those in normal plasma processing, and are not particularly limited, but for example, the degree of vacuum] OmTorr
~10 Torr, frequency 50 Hz ~ 50 MHz, discharge power 0.2 ~ IOW are preferable, and processing time is 30 seconds ~ 3
0 minutes is appropriate.

In the above plasma treatment, for example, as shown in FIG. 1, a pair of electrodes 2, 2 facing each other is provided in a reaction container 1 made of a Herjar, and a base material 4 is held between them by a rotating holder 3. For example, an apparatus may be used in which an AC power source 5 is connected to each electrode 2.degree. 2, thereby generating plasma between the electrodes 2. In addition, 6 is a shielding plate, 7 is a boat which is a container for storing an evaporation source such as an inorganic oxide, 8 is an electron beam source for evaporating the evaporation source,
9 is an exhaust pipe, 10 is a gas introduction pipe, and 11 is a shack for controlling the thickness of the inorganic oxide thin film.

In the method (1) of the present invention, the inorganic oxide thin film formed subsequent to ultraviolet irradiation or plasma treatment uses silicon oxide, aluminum oxide, titanium oxide, molybdenum oxide, tungsten oxide, zirconium oxide, tin oxide as the inorganic oxide. , glass, etc., or a mixture of two or more thereof.

These inorganic oxide thin films can be formed using ordinary thin film forming techniques such as vacuum evaporation, ion blasting, and sputtering.

The thickness of the inorganic oxide thin film to be formed is preferably 50 to 5000 angstroms. If the film thickness is less than 50 angstroms, it becomes difficult to impart hydrophilicity to the adhesive surface.

On the other hand, if the thickness exceeds 5000 angstroms, the inorganic oxide thin film is likely to peel off from the surface of the base material, and in the case of a gas permeable base material, its permeability may be impaired, which is not preferable.

Substrates that can be surface-treated by method (1) of the present invention include, for example, films, sheets, fibrous materials, and various molded products, and are not particularly limited. Furthermore, the material of the base material to be treated is not limited, and for example, surfaces of hard plastics, soft rubber-like materials, etc. can be treated.

In particular, intraocular lenses made of polymethyl methacrylate, polydimethylsiloxane, methyl methacrylate,
Butyl acrylate-1, siloxanyl methacrylate,
The method (1) of the present invention can be suitably applied to heart contact lenses and soft contact lenses made of fluoromethacrylate-1.

Next, in the method (2) of the present invention, under vacuum is usually 10 mTorr ~], Torr, preferably 30 ff
The pressure is between 1 TOrr and 300 III TOrr.

In method (2) of the present invention, the same ultraviolet lamp as in method (1) can be used as the ultraviolet lamp.

Further, the irradiation amount of ultraviolet rays and the concentrations of oxygen and ozone are also the same as in the method (1).

In method (2) of the present invention, if the amount of ultraviolet irradiation is small and the amount of oxygen and ozone is small, it is difficult to fully exhibit the effects of the present invention. In particular, in the absence of oxygen or ozone, a strong amount of ultraviolet light is required, which causes deterioration of the H radical. Furthermore, in addition to oxygen and ozone, non-polymerizable gases such as air, nitrogen, and ammonia, or polymerizable gases such as hydrocarbons, alcohols, and radically polymerizable monomers can be used.

Here, hydrocarbons include saturated hydrocarbons such as methane, ethane, propane, butane, ethylene, propylene,
Examples of unsaturated hydrocarbons such as butadiene, benzene, acetylene, and divinylacetylene; alcohols such as allyl alcohol and 2-propyl 1-ol; and radically polymerizable monomers such as N-vinylpyrrolidone and hydroxyethyl (meth). ) acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, sutyrene,
Examples include vinyl acetate, acrylic acid, acrylamide, and vinyl methacrylate.

The plasma processing conditions in method (2) of the present invention may be the same as those in normal plasma processing, and are not particularly limited, but for example, the degree of vacuum is 10 mTorr to 10 mTorr.
Torr, frequency 50 Hz to 50 M) Iz, and discharge power 0.2 to IOW are preferable.

The time for plasma treatment while irradiating ultraviolet rays is usually 1 to 180 minutes, preferably 5 to 120 minutes, and when the irradiation time is long, the irradiation may be performed intermittently, for example, 5 to 120 minutes.
By adopting a method such as irradiating the light for 5 minutes and then turning it off for 5 minutes, it is possible to prevent the molded product being treated from deteriorating due to the light. Further, the temperature of the base material during irradiation is usually 5 to 200°C, preferably 15 to 100°C.

In method (2) of the present invention, it is necessary to perform plasma treatment and ultraviolet irradiation at the same time, but it is possible to irradiate ultraviolet rays before plasma treatment, and then continue to perform plasma treatment while irradiating ultraviolet rays. It is also possible to irradiate ultraviolet rays during the plasma treatment.

A plasma processing apparatus equipped with parallel plate electrodes in the same reaction vessel used in the method (2) of the present invention and a 1600
FIG. 2 shows an example of a surface treatment apparatus equipped with an ultraviolet irradiation device having a wavelength range of 4,000 angstroms. This device includes a pair of electrodes 34.34 facing each other in a reaction vessel 31 constituted by a Herger, and a pair of ultraviolet ray dumps 35.3 facing each other at the top with a shielding plate 32 in between.
5 is provided, and the base material 40 is held in a rotating holder 33 having a rotating shaft in the center. For example, an AC power supply 36 is connected between the electrodes to generate plasma between the electrodes 34 and 34, and a power supply box 37 connected to an ultraviolet lamp 35 irradiates ultraviolet rays. Note that 38 is an exhaust pipe, and 39 is a gas introduction pipe.

In addition, examples of the base material that can be surface-treated by the method (2) of the present invention include those similar to those used in the method (1).

e. Examples The present invention will be explained in more detail below with reference to the drawings, but the present invention is not limited thereto.

Example 1 Using the reaction vessel 1 shown in FIG.
A polymethyl methacrylate plate 4 is held between the electrodes 2, silicon oxide powder is placed in the boat 7, and 10 cc of oxygen is
(STP)/min, while introducing into the reaction vessel 1,
Keeping the inside of the reaction vessel j at a vacuum level of 50 mTorr, the electrode 2
．． 2 was applied with alternating current power of 10 K 11 z to generate plasma and treated for 5 minutes. Next, the degree of vacuum is I x 1
0- 'Torr, electron beam F to boat 7
An electron beam generated by X8 was applied to deposit silicon oxide on the surface of the base material 4 to a thickness of 1000 angstroms.

The treated base material 4 was evaluated for changes in hydrophilicity over time and surface durability when left in the air. In addition,
Hydrophilicity can be evaluated by determining the contact angle of water.
Measured using P type J. In addition, the durability of the base material surface is
As shown in FIG.
A load of 13 kg is applied, and one side of the base material 4 is covered with double-sided tape 14.
Fix the sample table 15 with
After performing a sponge test without rotating, the contact angle of water was measured to evaluate hydrophilicity. The results are shown in Table-1.

Example 2 Using the reaction container 1 shown in FIG. 1, a base material having a width of 10 mm, a length of 20 mm, and a thickness of 0.5 M
A polydimethylsiloxane plate 4 is held between the electrodes 2 and 2, aluminum oxide powder is placed in the boat 7, and oxygen is
Occ (STP)/min, while maintaining the inside of the reaction container 1 at a vacuum level of 50 mTorr while introducing it into the reaction container 1.
After applying AC power of 10 KHz to electrode 2.2 to generate plasma and treating it for 5 minutes, the degree of vacuum was reduced to IXl0-6.
Raise the temperature to Torr, apply an electron beam to the boat 7, and apply aluminum oxide to the surface of the base material 4 at a rate of 1000 oz.
Deposited in loam thickness.

Regarding the treated base material 4, the change in hydrophilicity over time and the durability of the surface were examined in the same manner as in Example 1. The results are shown in Table-1.

Example 3 Using the reaction vessel 1 shown in FIG. 1, a base material of width 10+ma, length 20m, and thickness 0.5mm was prepared using a rotating holder 3.
Polymethyl methacrylate 1 plate 4 is held between electrodes 2 and 2, molybdenum oxide is placed in boat 7, and oxygen is added to
cc (STP)/+++in, while maintaining the inside of the reaction vessel 1 at a vacuum of 50 mTorr, applying alternating current power LOKIIy to the electrode 22 to generate plasma and treating it for 5 minutes. The degree of vacuum is I Xl0
The temperature was raised to -6 Torr, and an electron beam was applied to bows 1-7 to deposit molybdenum oxide on the surface of the substrate 4 to a thickness of 2000 Å.

Regarding the treated base material 4, the change in hydrophilicity over time and the durability of the surface were examined in the same manner as in Example 1. The results are shown in Table-1.

Example 4 Using a low-pressure mercury lamp, ultraviolet rays mainly having wavelengths of 1849 angstroms and 2537 angstroms were emitted from both sides of a polydimethylsiloxane plate 4 having a width of IQ mm, a length of 20 mm, and a thickness of 0.5 m in the atmosphere. 1 at room temperature
Immediately after irradiation for 5 minutes, a substrate was attached to the rotary holder 3 using the reaction vessel shown in FIG. 1, and silicon oxide was vapor-deposited under the same conditions as in Example 1.

Note that the amount of ultraviolet ray irradiation was 2.5 J/c+fl.

Regarding the treated base material 4, the change in hydrophilicity over time and the durability of the surface were examined in the same manner as in Example 1. The results are shown in Table-1.

Comparative Example 1 Using the reaction vessel 1 shown in FIG. 1, a base material having a width of 10 mm, a length of 20+n+++, and a thickness of 0.0 mm was placed using the rotating holder 3.
A 5 mm polydimethylsiloxane plate 4 is held between the electrodes 2, aluminum oxide powder is placed in the boat 7, and the degree of vacuum is set to 1. Xl, raised to 0-6 Torr, boat 7
An electron beam was applied to the surface of the base material 4 to deposit aluminum oxide to a thickness of 1000 angstroms.

Regarding the treated base material 4, the change in hydrophilicity over time and the durability of the surface were examined in the same manner as in Example 1. The results are shown in Table-1.

Table 1 Evaluation of hydrophilicity (contact angle of water) Example 5 Using the reaction vessel 31 shown in FIG. Hold the methyl methacrylate plate 40 and set the ultraviolet lamps 35, 35 7B) VLIV-040/A manufactured by Oak Co., Ltd.
-Using 2,206 lamps, irradiate ultraviolet rays from a distance of 30III11, and at the same time irradiate oxygen at 10cc (STP)/mi.
While introducing the electrode 34 into the reaction container 31 at
, 34 was applied with AC power of 10KIIz to generate plasma, and the treatment was carried out for 15 minutes.

The treated base material 40 was examined for changes in hydrophilicity over time and surface durability in the same manner as in Example 1. The results are shown in Table-2.

Example 6 Using the reaction vessel 31 shown in FIG. 2, a base material was placed on the rotary holder 33 with a width of 10 + no +, a length of 20 recesses, and a thickness of 0.5
Hold a polydimethylsiloxane plate of 40 mm and set the ultraviolet lamp at 35°35 to VUV-040/T Oak Co.
Using A-2,206 lamps, irradiate ultraviolet light for 5 minutes from a distance of 30 mm, turn off the light for 10 minutes, and at the same time irradiate oxygen for 10 minutes.
cc (STP)/min, while maintaining the inside of the reaction vessel 31 at a vacuum level of 5 Xl0-2 Torr, and generating plasma by applying AC power of 10 KHz to the electrode 34.34 for 30 minutes. Processed.

The treated base material 40 was examined for changes in hydrophilicity over time and surface durability in the same manner as in Example 1. The results are shown in Table-2.

Example 7 Using the reaction vessel 31 shown in FIG. 2, a rotating holder 33 with a base material having a width of 10 mm, a length of 20 m+n, and a thickness of 0.
Holding a 5 mm polymethyl methacrylate plate 40,
As ultraviolet lamp 35, 35 ■ VUV-0 manufactured by Oak Company
Using six 40/A-2.2U lamps, ultraviolet rays were irradiated for 10 minutes from a distance of 30 mm, and then oxygen was irradiated at 10 cc (SfP)/min while continuing to irradiate ultraviolet rays.

into the reaction vessel 3I, and the inside of the reaction vessel 31 is 5X10
The vacuum was maintained at -2 Torr, and AC power of 10 KHz was applied to the electrodes 34, 34 to generate plasma, and the treatment was carried out for 10 minutes.

The treated base material 40 was examined for changes in hydrophilicity over time and surface durability in the same manner as in Example 1. The results are shown in Table 2.

Example 8 Using the reaction vessel 31 shown in FIG. 2, the rotary holder 33 was used as a base material with a width of 0 mm, a length of 20 mm, and a thickness of 0.5 mm.
The reaction vessel 31 was held with unl polymethyl methacrylate 1 plate 40 and oxygen was supplied at 10 cc (STP)/min.
The inside of the reaction vessel 31 is heated to 5 Xl0-2 Torr.
Maintain the degree of vacuum at
was added to generate plasma and treated for 10 minutes,
While continuing to generate plasma, ultraviolet rays are applied.
．． 35t L7■ VUV-040/A-2,2 manufactured by Oichiku Co., Ltd.
Ultraviolet irradiation and plasma treatment were performed for 10 minutes from a distance of 30 marks using a U6 lamp.

The treated base material 40 was examined for changes in hydrophilicity over time and surface durability in the same manner as in Example 1. The results are shown in Table 2.

Example 9 Using the reaction container 31 shown in FIG. 2, a rotary boulder 33 with a width of 10III11, a length of 20 mm, and a thickness of 0.
5 Hold the hazy polymethyl methacrylate plate 40 and use the UV lamps 35, 35 as ■ VUV-040 manufactured by Oak Co.
/A-2.Using 216 lamps, illuminate the ultraviolet rays from a distance of 30 degrees, and at the same time supply oxygen at 10 cc (STP)/min and methane at 10 cc (STP)/min to the reaction vessel 3.
1, the inside of the reaction vessel 31 is 10 x 10
The vacuum level was maintained at -2 Torr, and AC power of 1.0 KHz was applied to the electrodes 34, 34 to generate plasma, and the treatment was carried out for 30 minutes.

The treated base material 40 was examined for changes in hydrophilicity over time and surface durability in the same manner as in Example 1. The results are shown in Table 2.

Example 10 Using the reaction vessel 31 shown in FIG. 2, a base material with a width of 10 mm, a length of 20 fflI11, and a thickness of 0 was placed on the rotary holder 33.
．． 5++u++ polymethyl methacrylate plate 40 is held, and as ultraviolet lamps 35, 35 ■ VU manufactured by Oak Co.
Using 6 V-040/A-2.2U lamps, ultraviolet rays are irradiated from a distance of 30 meters, and at the same time oxygen containing 3% by volume of ozone generated by an ozonizer is irradiated at 15 cc (STP)/m.
in, while introducing the reaction container 31 into the reaction container 31.
Maintaining a vacuum of 5 x 10-” Torr inside, electrode 3
4, 34, AC power 10K) Iz was added to generate plasma, and the treatment was carried out for 15 minutes.

The treated base material 40 was examined for changes in hydrophilicity over time and surface durability in the same manner as in Example 1. The results are shown in Table-2.

Comparative Example 2 Three reaction vessels shown in FIG. 2 were used, and a rotary holder 33 had a base material of 10 mm in width, 20 mm in length, and 0.5 mm in thickness.
The polymethyl methacrylate plate 40 is held, and as the ultraviolet lamps 35,
Using six A-2, 21J lamps, ultraviolet rays were irradiated for 15 minutes from a distance of 30 nm+m. In addition, the inside of the reaction vessel is 5Xl.
, the degree of vacuum was maintained at 0-''Tor'r.

The treated base material 40 was examined for changes in hydrophilicity over time and surface durability in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 3 Using the reaction vessel 31 shown in Fig. 2, a polymethacrylate 1 plate 40 with a width of 10+ nm, a length of 20 nm, and a thickness of 0.5 mm was held as a base material in a rotary holder, and oxygen was removed. 1
0 cc (STP)/min, was introduced into the reaction vessel 31, the inside of the reaction vessel 31 was maintained at a vacuum level of 5XIO-'' Torr, AC power of 10 HIz was applied to the electrode 34, 34 to generate plasma, and treatment was performed for 15 minutes. did.

The treated base material 40 was examined for changes in hydrophilicity over time and surface durability in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 4 Using the reaction vessel 31 shown in FIG. Toshite Oak Co., Ltd. VUV-040/A-
Using 6 2.2U lights, 1 UV ray is emitted from a distance of 30mm.
After 0 minutes of irradiation, oxygen was added at 10cc (STP)/mi.
n, into the reaction vessel 31, and inside the reaction vessel 31 at 5.
Maintain the vacuum level at X 10-” Torr and connect the electrode 3434
AC power of 10 Ktlz was applied to generate plasma, and the treatment was carried out for 10 minutes.

The treated base material 40 was examined for changes in hydrophilicity over time and surface durability in the same manner as in Example 1. Display the results -
Shown in 2.

Comparative Example 5 Using the reaction vessel 31 shown in FIG. 2, a polymethyl methacrylate plate 40 with a width of 10 m, a length of 20 ann, and a thickness of 0.5 m was held as a base material in a rotary holder 33, and oxygen was
c(STP)/min into the reaction vessel 31, the inside of the reaction vessel 31 was maintained at a vacuum level of 5 x 10-'' Torr, AC power of 10 KHz was applied to the electrode to generate plasma, and treatment was performed for 10 minutes. Later, ultraviolet lamp 35.35
As ■ VIIV-040/A-2, 2U manufactured by Oak Company
Using six lamps, ultraviolet rays were irradiated for 10 minutes at a distance of 30 mm.

The treated base material 40 was examined for changes in hydrophilicity over time and surface durability in the same manner as in Example. Display the results -
Shown in 2.

Comparative Example 6 Using the reaction vessel 31 shown in FIG. 2, a polymethyl methacrylate plate 40 having a width of 10 mm, a length of 20 mm, and a thickness of 0.5 mm was held as a base material in the rotating holder 33, and 10 cc of oxygen was held as a base material.
(STP)/min, 10cc of methane (STP)
/min, while maintaining the inside of the reaction vessel 3I at a vacuum level of 10 x 10-2 Torr,
AC power of 1.0 KHz was applied to the electrodes 34, 34 to generate plasma, and the treatment was carried out for 30 minutes.

The treated base material 40 was examined for changes in hydrophilicity over time and surface durability in the same manner as in Example 1. Display the results -
Shown in 2.

FIG. 2 is a cross-sectional view of a hydrophilic thin film formed by

3t--reaction vessel, 33- Rotating holder, 36-----AC power supply, boat, 38---exhaust pipe, shutter inorganic membrane, power box.

electrode, Base material, Shield, electron beam source, 39---Gas introduction pipe, modified membrane, ultraviolet lamp,

Claims (2)

[Claims] (1) After modifying the base material surface by irradiating the base material surface with ultraviolet rays in the presence of oxygen and/or ozone or by treating it with non-polymerizable gas plasma, inorganic A surface treatment method characterized by forming an oxide thin film. (2) A surface treatment method characterized by subjecting the surface of a substrate to plasma treatment while irradiating ultraviolet rays under vacuum in the presence of oxygen and/or ozone.