JPH04374A - Production of hardened protective film on surface of plastic substrate - Google Patents

Abstract

PURPOSE:To form a hardened protective film on the surface of a plastic substrate with satisfactory bonding strength by forming an active layer on the surface of the substrate by plasma treatment. CONSTITUTION:At least one kind of inert gas selected among He, Ne, Xe, Kr and Ar, SiH4, N2O and CH4 are used as reactive gases and an active layer is first formed on the surface of a plastic substrate 10 with plasma of the inert gas. A CVD reaction is then caused with a gaseous mixture of SiH4 with N2O and CH4 to form an SiO2-SiC-SiN film having high adhesive strength to the plastic substrate and high hardness.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to window materials for buildings and houses, window materials for aircraft, ships, automobiles, etc., as well as electronic materials, optical materials, display materials, etc. The present invention relates to a method for manufacturing a hardened protective film on the surface of a plastic substrate that requires hardness, wear resistance, scratch resistance, etc.

[Conventional technology]

Conventionally, a plasma polymerization method as described below has been used on a trial basis as a technique for increasing the hardness of a plastic surface and improving wear resistance and scratch resistance. In FIG. 7, an organosilicon compound monomer 01 is introduced into a vacuum container 03 via a monomer flow rate regulating valve 02. A high frequency electrode 04 and a ground electrode 05 are installed in parallel in the vacuum container 03, and a plastic substrate 06 is placed on the ground electrode 05. The high frequency electrode 04 has a matching box 07.
Power is supplied from a power source 08 via the power source 08. Note that the vacuum container 03 is evacuated by a vacuum pump 010 via a valve 09.

Now, in FIG. 7, in order to form a cured protective film on the plastic substrate 06, the vacuum container 03 is moved to the vacuum pump 010.
For example, reduce the pressure to 0. Set to about OI Torr. Next, the monomer flow rate adjustment valve 02 is opened, and organosiliconized Kaneko Tsumer 01, such as octamethylcyclotetrasiloxane, is introduced into the vacuum container 03, and the pressure is increased to about 5. Set to OX 10-2 Torr. Next, for example, the output from the IzO high frequency power supply 04 (frequency 13.56M) is approximately 1
00W, generate plasma and power from 5.0 to 8.0
A high hardness film is deposited on the plastic substrate 06 for a few minutes.

The film obtained as described above is a highly hard film whose composition is silicon, oxygen, and carbon.

[Problem to be solved by the invention]

In the conventional method described above, the following problem arises because the plastic substrate 06 is placed between the two electrodes 04 and 05 to form a film.

(1) Since a dielectric plastic substrate is installed between the electrodes, a high frequency power source such as 13
．． A 56MHz power supply is required. Note that with DC and low frequency power supplies, if there is a plastic substrate between the electrodes, this restricts the supply of electrons from the electrodes, making it difficult to generate plasma with -like intensity. The high frequency power is 2 above.
When supplied to a single electrode, the area in which uniform plasma is generated is small due to the voltage drop due to the skin effect. Therefore, in the conventional device, the area of the plastic substrate is approximately 50
cm x 50 cm is the limit, and it is very difficult to increase the area beyond that.

(2) Although the deposited SiC-based thin film is a highly hard film,
Since the bonding force between the plastic substrate and the high hardness film is not strong enough, there is a drawback that it is easy to peel off.

[Means to solve the problem]

The inventors of the present invention have conducted extensive research to overcome the drawbacks of the conventional methods described above, and have discovered that it is effective to form an active layer on the surface of a substrate by plasma treatment, and have arrived at the present invention. That is, the present invention provides (1) first forming an active layer on the surface of a plastic substrate using at least one inert gas plasma as a reactive gas, and then forming an active layer on the surface of a plastic substrate;
3102 and/or Si on the surface of the plastic substrate by mixed gas plasma with O and/or C1.
A method for producing a cured protective film on the surface of a plastic substrate, characterized by forming a C film, and first forming an active layer on the surface of the plastic substrate using at least one inert gas plasma as a reactive gas, and then forming an active layer on the surface of the plastic substrate using 5IH4 and NH, S is applied to the surface of the plastic substrate by mixed gas plasma with
The present invention relates to a method for manufacturing a hardened protective film on the surface of a plastic substrate, which is characterized by forming an iN film.

The present invention is particularly preferably carried out in the following embodiments.

(1) As the plasma generation electrode, an electrode with an uneven surface is used in place of one of two conventional opposed flat plate electrodes to facilitate generation of strong glow discharge.

(2) By applying a magnetic field in a direction perpendicular to the plasma generation electric field, and changing the strength of the magnetic field in a sinusoidal or rectangular wave manner, simultaneously changing the direction to positive or negative, The spatial distribution and temporal changes in plasma density can be averaged.

As a result of the above, even if the reaction vessel and electrodes are increased in size, the product will not be uneven, and large-area plasma CVD of 3m x 5m class can be achieved.
(Chemical Vapor Dep-osit
ion) film can now be obtained.

(3) As a reaction gas, He, Ne, Xe,
At least one inert gas selected from Kr''J3 and ^r (hereinafter referred to as the inert gas), 5IH1,
Using N20, the film forming procedure is as follows: First, an active layer is formed on the surface of the plastic substrate by plasma of the inert gas, and then CV D (Chemical Vapor) is formed by plasma of a mixed gas of SiH4 and N20.
By causing a reaction (deposition) and forming a 5il12 film, a SiO□ film with strong adhesion to the plastic substrate and high hardness was obtained.

The reaction gas is the inert gas, SiH, and CH.

In this case, the film forming procedure is the same as described above: first, an active layer is formed on the surface of the plastic substrate using plasma of the inert gas, and then a CVD reaction is caused using plasma of a mixed gas of 5IH4 and CH to form a SiC film.

Furthermore, the reaction gas is the inert gas, 5i)1. and NH8
In this case, the film forming procedure is to first form an active layer on the surface of the plastic substrate using the inert gas plasma, and then
A CVD reaction is caused by plasma of a mixed gas of 5IH4 and NH3 to form a SiN film.

The present invention is generally carried out under the following conditions: (a) Range of output voltage of the plasma generation reservoir: several tens of volts to several tens of volts
0V, in exceptional cases several V0 (b) Range of magnetic field strength: several tens of gauss to 200 gauss, in exceptional cases 8
00-900 Gauss.

(c) Pressure range during active layer formation - approximately 0.01 Torr to 100 Tarr (d) Pressure range during formation of 5iO- and SiC (inside reaction vessel) - 0. I Torr to about 100 Torr (e) Pressure range during SiN formation: 0. Approximately ITorr to 100 Torr [Example] The present invention will be described below based on an apparatus of an example shown in FIG.

1 is a reaction vessel in which a plastic substrate 10 and a cathode 2 and an anode 3 for generating plasma are installed. 2 is the cathode, whose structure is shown in Figure 2 (a), et al.
, (C), (6) and (e),
It takes the form of a flat plate with a grid or similar structure. Note that it is installed facing the anode 3. 3 is the anode, which has a flat plate structure. 4 is a plasma generation power supply,
It uses a DC power supply. Note that an alternating current or high frequency power source may be used instead of the direct current power source. 5 is a magnetic field generating power source, which is an AC power source that can set an arbitrary frequency. A coil 6 surrounds the reaction vessel 1 and is supplied with electric power from the magnetic field generating power source 5. A pressure gauge 7 detects the pressure in the reaction vessel 1 through a pressure detection hole 21, and transmits a signal to a pressure regulator 8, which will be described later. A pressure regulator 8 is used in conjunction with the pressure gauge 7 and a vacuum pump 9, which will be described later. Reference numeral 9 denotes a vacuum pump which evacuates the degree of vacuum in the reaction vessel 1 to a predetermined set value via the pressure regulator 8 mentioned above. 13 is the inert gas supply source, and 16 is a mass flow controller for the inert gas. 14 and 15 are Si
H, gas supply source and N20 supply source. 17 and 18
are 5IH4, N, and O mass flow controllers, respectively. 19 and 20 are first and second valves, respectively, for the inert gas.

and opens and closes flow paths for SiH, N, and O gases.

Reference numerals 22 denote exhaust holes, each of which is connected to the vacuum pump 9.

24 is a reaction gas introduction hole for the inert gas.

SiH, N, and O gases are introduced.

In FIG. 1, a plastic substrate 1o was placed between an anode 3 and a cathode 20 as shown.

The inside of the reaction vessel 1 is evacuated by driving the vacuum pump 9, and then the first valve 20 is opened and the mass flow controller 16 of the inert gas is used to exhaust the inside of the inert gas supply source 1.
3, the inert gas was supplied to the reaction vessel 1 through the reaction gas introduction hole 24 at a flow rate of about 50 cc/min. Note that the pressure inside the reaction vessel 1 is detected by the pressure gauge 7 through the pressure detection hole 21, and the information is transmitted as an electric signal to the pressure regulator 8, and the pressure regulator 8 and the vacuum pump 9 are linked. The pressure was set to an arbitrary value in the range of about 0.05 to 0.5 Torr by operating the motor at a certain temperature.

Next, when power was supplied from the plasma generation power source 4 to the anode 3 and cathode 2, glow discharge plasma of the inert gas was generated between the electrodes 2 and 3.

In this case, as shown in Figure 2, the structure of the cathode 2 is a combination of a flat plate and a grid (a) or an octopus pot (6), so as shown in Figure 3, the structure of the cathode 2 is Negative glow accompanied by strong light emission occurs.

By the way, the positive column is generated surrounding the plastic substrate 10. The output voltage of the plasma generation power source 4 is kept constant, and the inert gas pressure in the reaction vessel 1 is set to 0. I
It was found that when the plasma current was varied from Torr to about I Torr, the plasma current increased significantly up to around 0.3 Torr, as shown in FIG. 4, and stabilized above that point. That is, the structure of the cathode 2 is called a hollow cathode. Therefore, the inert gas plasma with high plasma density is obtained. Further, the coil 6 and the magnetic field generating power supply 5 generate a magnetic field B in a direction perpendicular to the electric field pressure generated between the electrodes 2 and 3. Then,
As shown in Figure 5, in the past, the strength of the magnetic field was zero (Figure 5A).
), the plasma current was a small value. However, when the strength of the magnetic field exceeds about 80 Gauss, the plasma current increases significantly. Then, the direction of the magnetic field B generated by the coil 6 is as shown in Fig. 6 (in the case of downward direction perpendicular to the paper surface of Fig. 6: mark ◎; in the case of upward direction, mark 20).
, positive and negative alternately, the action of the electric field E and the magnetic field B causes the plasma to be swayed in a direction parallel to the electrode 2.3 by a force called EXE drift. That is, the effects of applying the magnetic field B are to improve the plasma density and to average the plasma density spatially and temporally by shaking the plasma.

Therefore, the surface of the plastic substrate 10 undergoes a chemical reaction due to the plasma of the inert gas having a high plasma density, and the chemical composition changes to a depth of about 10 to 1000 layers below the surface. As a result of investigation using infrared spectroscopy and electron spin resonance spectroscopy, it was found that functional groups such as CH and -C'H2 were introduced into the plastic surface to form a chemically active layer.

Plastic substrate 10 formed by the above-mentioned inert gas plasma
After forming the surface active layer for about 30 seconds to about 10 minutes, the voltage of the plasma generation power source 4 was reduced to zero. Then, the first valve 19 was closed to exhaust the inert gas in the reaction vessel.

Next, silane SiH, gas source 14 and nitrous oxide N
From 2O gas supply source 15, 5IH4 mass flow controller 17 RU N207 x 7 C1-
The second valve 20 was opened via the controller 18, and 5IH4 gas and N2O gas were supplied into the reaction vessel 1 through the reaction gas introduction hole 24 at a flow rate of about 25 cc/min, respectively. The internal pressure of the reaction vessel 1 is detected by the pressure gauge 7 through the pressure detection hole 21, and the vacuum pump 9 of the pressure regulator 8 is operated in conjunction with the pressure to approximately 0.05 to 0.5 T.
It was set to an arbitrary value within the range of orr.

When power is supplied from the plasma generation power source 4 to the anode 3 and cathode 2, 5i)1. A glow discharge plasma of N20 and N20 was generated between the electrodes 2 and 3. In this case, as described above, a negative glow accompanied by strong light emission occurs near the cathode 2. Furthermore, the coil 6 and the magnetic field generating power source 5 generate a magnetic field B in a direction perpendicular to the electric field E generated between the electrodes 2.3, and as described above, when the magnetic field B is alternately changed between positive and negative, EXE
The plasma was shaken by the drift.

As a result, the plasma density was averaged spatially and temporally.

If a plasma of 5IH4 and N2[+ mixed gas is generated in this way, plasma CVD (Chemical
A film of Sin is deposited on the plastic substrate 10 by the vapor deposition reaction. The film formation time was about 1 to 2 hours.

Finally, the output power of the plasma generation power source 4 and the magnetic field generation power source 5 is reduced to zero, and the 5it1. and exhaust the N2O gas. Although not shown, when taking out the plastic substrate 10 from the reaction vessel 1, Ar or N2 gas is introduced into the reaction vessel 1 to almost completely exhaust SiH4 gas, and then the door is opened and taken out. Ta.

In this example, a SiO2 film was deposited on the surface of a polycarbonate plate and an acrylic plate with an area of 1 m x 2 m by the above method. Thickness is approximately 5 μm 1 hardness is Vickers hardness 2.
It was about OOO to 3,000. Adhesion strength is
As a result of testing by applying adhesive tape and peeling it off, it was found to be sufficiently strong.

In the above embodiment, the inert gas, 5i
Although n4 and N20 were used, SiC films and SiN films were obtained in the same manner as above in the case of the following reaction gases, respectively.

(a) The inert gas, 5IH4, CH- (b) The inert gas, SiH,, NH = The inert gas in (a) and (b) above is from the inert gas supply source 13 as above,
, were supplied from 14 gas supply sources, and CH4 and NH5 were supplied from 15 gas supply sources to form a cured film in the same manner as above.

〔Effect of the invention〕

According to this invention, window materials for buildings and houses, etc.
In plastic surface treatment methods that require high hardness, abrasion resistance, and scratch resistance as surface properties, such as window materials for aircraft, ships, and automobiles, and electronic materials, optical materials, and display materials, large areas and It has become possible to manufacture surface-hardened protective films made of materials such as 5102, SiC, and SiN, which have strong bonding strength with the plastic substrate. This is of significant industrial value.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the device configuration according to the first embodiment of the present invention, and FIG. 2 (a), (b), (C), (6) and (
e) is a conceptual diagram showing the electrode structure of the present invention, and Fig. 2(a) is a conceptual diagram showing the electrode structure of the present invention.
') and are the cross-sectional views of Figures 2(a) and 3), respectively.
The figure is a conceptual diagram showing the glow discharge plasma generated by the electrode of the present invention, Figure 4 is a graph showing the relationship between the current of the glow discharge plasma generated by the electrode of the present invention and the pressure inside the reaction vessel, and Figure 5 is a graph showing the relationship between the glow discharge plasma generated by the electrode of the present invention and the pressure inside the reaction vessel. Graphs showing the relationship between the strength of the applied magnetic field and the plasma current when the magnetic field is , and Figure 7 is
FIG. 1 is a configuration diagram showing a conventional device.

Claims (2)

[Claims] (1) Firstly, at least one inert gas plasma is used as a reaction gas to form an active layer on the plastic substrate surface, and then SiH_4, N_2O and/or CH_
4. A method for producing a hardened protective film on a plastic substrate surface, the method comprising forming a SiO_2 and/or SiC film on the plastic substrate surface using mixed gas plasma. (2) First, at least one inert gas plasma is used as a reactive gas to form an active layer on the surface of the plastic substrate, and then a mixed gas plasma of SiH_4 and NH_3 is used to form a SiN film on the surface of the plastic substrate. A method for producing a cured protective film on the surface of a plastic substrate.