JPS62240762A - Formation of thin film - Google Patents

Abstract

PURPOSE:To improve the wear resistance of a synthetic resin body by forming the film consisting of silicon oxide on the body which has been applied with sputtering etching in the low-voltage discharge atmosphere of an inactive element as the pretreatment, and firmly depositing a silicon oxide film on the surface of the synthetic resin body. CONSTITUTION:The synthetic resin body 11 is fixed to a substrate holder 3, the inside of a treating vessel 1 is evacuated, and the pressure in the vessel 1 is regulated by introducing 8 an inert gas such as Ar. A voltage is then impressed on the holder 3 to form electric discharge conditions, the inert gas is struck against the surface of the resin body 11 to cut the high molecular chain of the resin body 11, and a radical is formed. A voltage is then impressed on an SiO2 target 2 to generate sputter discharge between the resin body 11 and the target 2. The alcohol droplets remaining on the resin body 11 is blown off by dry gaseous N2 to clean the surface. The resin body 11 is then fixed to a substrate holder in the treating vessel of a magnetron type sputtering device, and the film of silicon oxide is formed on the surface of the resin body 11 by an ordinary method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for forming a hard film on the surface of a resin product.

[Prior art]

Traditionally 2. Inorganic glass has been widely used in the windows of automobiles, etc., but recently, the use of transparent resin (resin glass), which is lightweight and has excellent processability, is being considered in place of inorganic glass. . However, resin glass has the disadvantage that it is inferior to inorganic glass in abrasion resistance.

Also, parts as 5 mechanical elements, such as gears.

Resins are also being used instead of metals due to their superior moldability. However, there are limits to its use in terms of wear resistance and the like.

In order to compensate for the above-mentioned drawbacks of resins, technology has been developed to improve wear resistance by forming a highly hard inorganic film such as Sin on the surface of the resin by vacuum evaporation, sputtering, ion blating, etc. Are known. As one of them, before membrane formation.

There is a method of sputter etching the base resin surface in advance in an oxygen gas discharge atmosphere (Japanese Patent Laid-Open No. 59-5
No. 0402). In this method.

By bombarding the base resin with oxygen particles accelerated by a discharge electric field, polymer chains are cut to generate highly reactive radicals. As a result, the radicals are strongly bound to the formed film, and the film is firmly attached to the resin.

However, the radical 5 above combines with oxygen.

This may be due to a decrease in the number of bonds with the constituent elements of the film, but there was a problem in that the adhesion of the film was insufficient and the wear resistance of the base resin could not be maintained.

[Problem that the invention seeks to solve]

Therefore, 3 the present inventors discovered that the adhesion of the above film was insufficient,
We proceeded with the study with the aim of solving the problem that the wear resistance did not improve.

In order to improve the adhesion of the film formed on the resin surface, the inventors discovered that strong chemical bonds, such as covalent bonds, should be created between the polymer constituent atoms on the resin surface and the film constituent atoms. I thought it was necessary.

In order to achieve this, we focused on a method in which the resin surface is exposed to low-pressure discharge in an inert element such as argon (Ar) before film formation. In other words, various atoms and excited species obtain energy through discharge under reduced pressure.

When ions and the like collide with the surface of the resin, bonds (C-H, C-0, C-C, etc.) in the polymer of the resin are cut, and radicals are generated. When an inert element is used, there are fewer elements that bond with radicals, so there is less opportunity for radicals to disappear. Therefore, when a film is formed thereafter, the chances of forming strong chemical bonds such as covalent bonds increase between the film-forming substance and radicals, and it is thought that the adhesion strength of the film increases. As a result of various studies on these matters 1
The present invention has been accomplished.

[Means for solving problems]

The present invention consists of a pretreatment process in which a synthetic resin body is subjected to sputter etching in a low-pressure discharge atmosphere of an inert element, and a film formation process in which a film made of silicon oxide is formed on the synthetic resin body subjected to the pretreatment process. This is a thin film forming method characterized by the following.

The synthetic resin body used in the present invention is a compound having an acrylic acid group or a methacrylic acid group at least on its surface, or a compound obtained by adding a photopolymerization initiator to an intermediate 9 polymer thereof and photopolymerizing it.

refers to something that is formed by A specific example of these compounds is polymethyl methacrylate.

There are resins such as polycarbon ester. The resin may be in the form of a plate-shaped material or a component such as a gear. These compounds may be provided as a layer on the surface of the base material. In this case, the thickness of this layer may be approximately several μm, and the base material may be a resin material that adheres well to the constituent resins of the two layers. That's fine.

The present invention will be explained below using the sputtering apparatus illustrated in FIG. This device consists of a processing tank 1 and a sink installed in it.
, target 2. A high frequency voltage can be applied to the substrate holder 3, the shutter 4, the target 2, and the substrate holder 3 from a high frequency power source 5 via a changeover switch 6 to cause discharge in the processing tank l. There is.

On the other hand, the exhaust lower of the treatment tank 1 is equipped with an exhaust pump (not shown).
In addition, the barrier pull leak valve 8 is connected to an inert gas supply source (
(not shown).

In the pretreatment process of the present invention, first, the synthetic resin body 1) is attached to the substrate holder 3, the air in the treatment tank 1 is exhausted, and then an inert gas such as Ar, helium (He), neon (Ne), etc. is introduced from the barrier pull leak valve 8,
The pressure in the tank is adjusted to about 3 to 4 x 10-'torr.

Next, the changeover switch 6 is turned on to the side where voltage is applied to the substrate holder 3, and a discharge state is created with a power of several tens to hundreds of watts. In this state, the inert gas hits the surface of the synthetic resin body, severing the polymer chains of the synthetic resin and generating radicals. After processing for a desired time, voltage application is stopped. Since the atmosphere is an inert element atmosphere during or after the treatment, the generated radicals can exist without disappearing.

Next, a film forming process is performed on one synthetic resin body.

First, the selector switch 6 is switched to the SiOz target side, a voltage is applied to the target, and sputter discharge is caused between the three synthetic resin bodies and the target. It is preferable to switch the voltage as quickly as possible while continuing to introduce the inert gas and at a low pressure. The reason for this is that nine steps are carried out before the radicals disappear, thereby increasing the adhesion to the SiO□ film.

After the start of sputtering discharge, it is preferable to perform pre-sputtering for several minutes, and then the shutter 4 is opened to sputter the target material, SiO□.

S i Oz that was sputtered and reached the surface of the 2 synthetic resin body
2 combines with the radicals generated on the surface of the synthetic resin body and is deposited one after another, forming a film of Sin and growing.

After performing the film forming process for a desired time, the voltage application and the introduction of the inert element are stopped, and the synthetic resin body 2 is taken out from the treatment tank.

FIG. 2 schematically illustrates a cross section of a film formed on the surface of one synthetic resin body. 5iO on the surface of the synthetic resin body 1)
A Z film 12 is formed over the inert gas discharge treated surface. Note that this synthetic resin body has a hardened surface layer 1) 2 formed on the surface of a resin base material 1) 1.

The thickness of the SiO□ film is preferably in the range of 1,000 to 7,000 angstroms (angstroms); if it is thinner than this range, it becomes a complete film, and if it is 'bl, Py-, it is likely to peel off from the synthetic resin body and its wear resistance will decrease. .

To measure the film thickness, prepare another glass substrate during processing, draw an organic mask on a part of the surface, remove the mask after film formation, and measure the step at the boundary of the film using a surface roughness meter. This can be done by using

In order to prevent the synthetic resin body from deforming or deteriorating due to temperature rise during film formation, a magnet 9 is attached to the back side of the target to concentrate the discharge near the target.
A so-called magnetron type sputtering device may also be used.

A 5-taper abrasion test was conducted to examine the abrasion resistance and adhesion of the formed synthetic resin body. After the test, the amount of increase in haze value (haze value) due to wear marks formed on the surface of the synthetic resin body was determined and evaluated.

What is a taper wear test? A test sample is placed on a rotary table, and two abrasive-containing rubber wear rings are placed on top of this.
It is made to contact each other and roll. After being transferred a predetermined number of times under a predetermined load, the haze value of one synthetic resin body is measured. Note that the haze value I) is the rate of light scattering due to scratches on the sample surface calculated using white light using the following formula.

However, T is the amount of light incident on the synthetic resin body, T2 is the amount of light transmitted through the synthetic resin, and T3 is the amount of diffused light 1. T4 is the amount of diffused light transmitted through the synthetic resin body.

The fewer the wear scars caused by the worn wheels, the lower the haze value H becomes. In other words, the lower the increase (%) in the haze value after the test compared to the haze value of the synthetic resin body before the test, the higher the S
It can be said that the iO□ film has strong adhesive strength and good wear resistance.

FIG. 3 illustrates the relationship between the measured increase in haze value and 17 of the SiO2 film. Curve 1 in the figure shows the case where the film was formed according to the present invention, and Curve 2 shows the case where the film was formed after sputter etching with oxygen as a conventional example. Comparing the two lines, the film formed according to the present invention is 5
It can be seen that the increase in haze value is small over the entire thickness range of the i02 film, and it has strong adhesion and high abrasion resistance.

〔Effect of the invention〕

According to the present invention, prior to forming the SiO□ film on the surface of the synthetic resin body, a pretreatment step is performed using an inert element such as Ar, thereby firmly adhering the SiO□ film to the surface of the synthetic resin body. At the same time, the wear resistance of the synthetic resin body can be improved.

〔Example〕

Hereinafter, one aspect of the present invention will be explained in detail.

Example 1 Polymethyl methacrylate resin (PMMA: trade name Acrylite AR) with one surface cured as a synthetic resin body (
A size of 100 x 100 x 3 dragons was prepared. These synthetic resin bodies were stored in a desiccator, dehydrated, and then wiped several times with dust-free gauze soaked in ethanol or isopropanol. Furthermore, the alcohol droplets remaining on the synthetic resin body 2 were blown off with dry nitrogen gas to clean the surface.

Next, in order to perform the pretreatment process of the present invention, the synthetic resin body 1 was attached to the substrate I and the router in the processing tank of a magnetron type sputtering device, and the processing tank was evacuated. When the pressure inside the treatment tank reaches 1 to 2X 10-5 torr due to the exhaust, Ar as an inert element is introduced into the tank,
Adjust the flow rate so that the pressure is 3.5 x 10-3 torr and continue evacuation. In this state, high frequency (13,
A voltage of 56 MIIZ) was applied to the substrate holder. The input power was set to 100 W, and discharge was maintained for 30 minutes. Thereafter, the application of high-frequency power was once stopped, and the voltage application changeover switch was quickly changed to connect to the SiO□ target, and power was then applied again to perform the film-forming process. Note that the Ar gas flow rate was maintained at approximately the same pressure continuously from the pretreatment step. After pressing for 2 minutes, Si
A shutter provided between the O□ target and the substrate holder was opened, and 5 tots of film were formed on one synthetic resin body. After maintaining the sputter discharge for 20 minutes, the power supply was stopped, and at the same time, the introduction of Ar was also stopped. Furthermore, after about 10 minutes had passed, the atmosphere was introduced into the treatment tank and one synthetic resin body was taken out.

The thickness of the SiO□ film was approximately 3000 mm.

A taper abrasion test was performed on the treated synthetic resin body formed into a film through the above process, and the abrasion resistance and adhesion of the SiO□ film were investigated. As a result, the increase in haze value was 180%, indicating good wear resistance. As a comparative example,
Ar is replaced by nitrogen gas (NZ).

The procedure was the same as in the second example except that the pretreatment step was performed in place of oxygen gas (0,), and S was used without pretreatment.
A synthetic resin body on which an iO□ film was formed was obtained. The increases in haze value measured for these comparative resin bodies were 2.9%, 3.0%, and 2.4%, respectively.

Example 2゜Processing was carried out by varying only the film formation time of Example 1,
Synthetic resin bodies with SiO□ film thicknesses of 500, 1,000, 1,700, 5,000, aooo, and 10,000 were obtained. The increase in each haze value is 3.7%,
2.4%, 1.7%, 169%, 2.9% and 3.0
%Met. On the other hand, as a comparative example, a Sin film having the same thickness as each was formed in the same manner as in this example except that Ar was replaced with 02 and pretreatment was performed. The respective increases in haze value are 4.5%, 3.6%, 3.6%,
3.0%.

They were 5.5% and 5.1%.

Example 3: Polycarbonate ester resin (PC: trade name: Lexan Sheet MR4000) with one surface cured as a synthetic resin body (dimensions:
Example 1 except that lOO100X100X3 was used.
processed in the same way. The thickness of the formed SiO□ film was approximately 3000 mm, and the increase in haze value was 1.4%.

As a comparative example, one was pretreated by replacing Ar with N2 or Ol, and the other was not pretreated.
A 5in2 film with a thickness of 3,000 people was formed. These haze value increases are 3.4%, 3.5%, and 2.5%, respectively.
It was 9%.

From these Examples and Comparative Examples, it can be seen that when the pretreatment is performed in Ar discharge, the 5iOz film firmly adheres to the synthetic resin body and the wear resistance of the synthetic resin body is improved.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the sputtering apparatus used to explain the present invention, Fig. 2 is a schematic sectional view showing the structure near the surface of a synthetic resin body formed into a 5 in 2 film according to the present invention, and Fig. 3 is a schematic diagram of the sputtering apparatus used to explain the present invention. FIG. 3 is a diagram illustrating the relationship between the thickness of the SiO□ film formed according to the invention and the amount of increase in haze value.

Claims (3)

[Claims] (1) Consisting of a pretreatment process in which a synthetic resin body is subjected to sputter etching in a low-pressure discharge atmosphere of an inert element, and a film formation process in which a film made of silicon oxide is formed on the synthetic resin body subjected to the pretreatment process. A thin film forming method characterized by: (2) The thin film forming method according to claim (1), wherein the film forming step is performed by a sputtering method. (3) Claim (1) characterized in that the film forming process forms a film with a thickness of 1000 to 7000 Å.
and the thin film forming method described in (2).