JPH03226555A - Film formation on plastic substrate - Google Patents

Abstract

PURPOSE:To form a sound and dense film excellent in adhesive strength and durability by irradiating a plastic substrate with ultraviolet rays and an ion beam before vapor deposition or before vapor deposition and in the course of vapor deposition at the time of forming a film by a vacuum deposition method. CONSTITUTION:For example, an acrylic lens 2, as a substrate, is attached to a rotary dome 4 in a vapor deposition chamber 3 in a vacuum deposition apparatus 1, and a low pressure mercury lamp 7 in the chamber 3 is lighted for >=1min, by which the whole surface of the dome 4 and the whole internal wall of the chamber 3 are diffusedly irradiated with ultraviolet rays. Subsequently, the inside of the chamber 3 is evacuated, and, when a degree of vacuum of <=1X10<-1>Torr is reached, the mercury lamp 7 is extinguished. When the degree of vacuum in the chamber 3 becomes <=1X10<-5>Torr, the mercury lamp 7 is lighted again, and simultaneously, ion beam irradiation from an ion gun 8 and neutralization electron beam irradiation from a neutralizer 9 are carried out for >=1min, respectively. Then, a vapor deposition material 5 of MgF2 is vapor-deposited onto the surface of the lens 2 by an electron beam vapor deposition method by means of an electron gun 6 and formed into a film. Owing to the above- mentioned irradiation with the ultraviolet rays and the ion beam, impurities can be removed from the substrate surface and this substrate surface can be activated, and the purposes can be accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of forming a thin film on a plastic substrate, and particularly to a method of forming a thin film on a plastic substrate in order to improve the durability and adhesion of the thin film.

3. Prior Art] In recent years, plastics have been increasingly used instead of inorganic glass as materials for optical parts such as lenses, mirrors, and prisms.The main reason for this is that they can be manufactured at low weight and low cost. This is because it has the advantage of being able to form a shape and having a high degree of freedom in shape.Also, due to these advantages, it has recently been widely used for various parts other than optical parts.

However, parts made of these plastics have inferior abrasion resistance and friction resistance compared to glass or metal, and therefore pose many practical problems unless some kind of surface treatment is applied. In particular, when plastic is used as an optical component, it is necessary to form an optical thin film as in the case of optical glass. In the case of optical glass, the thin film can be deposited on heated optical glass, so the adhesion between the optical glass and the optical thin film is good; however, in the case of plastic, the deposition can be done by heating the substrate. Since it is difficult to perform this process, there has been a problem that the adhesion and adhesion of the thin film to the plastic substrate are poor, resulting in poor durability.

Therefore, in order to solve this problem, Si0ZrO
A method of using □, MgF, etc. as a layer in contact with a plastic substrate, and a method of forming an organic material as a primer layer by spin-coating, dipping, plating, etc., and depositing a dielectric film thereon have been proposed. Furthermore, Japanese Patent Laid-Open No. 63-20073 discloses a method of surface modification by subjecting the surface of a plastic substrate to a plastinizing treatment before vapor deposition. Further, Japanese Patent Laid-Open No. 6111503 discloses a method of irradiating the surface of a substrate with an ion beam in order to form a hard fluoride film with excellent adhesion at low temperatures.

[Problem to be solved by the invention]

In the conventional film forming method described above, the materials that can be deposited in the first layer are limited to SiO2, etc., so a common problem is that it is extremely difficult to satisfy desired characteristics when designing an optical thin film. was there. In addition, with pretreatment methods that use organic materials such as a primer layer, good reproducibility cannot be obtained unless sufficient attention is paid to liquid management and the working environment, and furthermore, it is difficult to obtain a There are many steps involved, and there are disadvantages in terms of cost and yield. Moreover, plasma treatment of the substrate surface is not a good method because the surface may be contaminated by contamination within the chamber. Furthermore, in the method of forming a film while irradiating the substrate surface with an ion beam, especially in the case of a plastic substrate,
The adhesion between the film and the substrate was not sufficient and could not be put to practical use.

The present invention aims to solve the above-mentioned problems of the conventional technology by forming a thin film on a plastic substrate, which has good adhesion and durability, and has properties similar to those formed on a glass material. The purpose is to provide a method for forming a film.

[Means and effects for solving the problem] That is, when forming a film on a plastic substrate by vacuum evaporation, the present invention irradiates the surface of the plastic substrate with ultraviolet rays and an ion beam before or during the evaporation. A method for forming a film on a plastic substrate is characterized by the following.

In a preferred embodiment of the present invention, the Ot gas is 1xlO-5T
Ultraviolet rays and ion beams are irradiated while being introduced into the drying room at a low partial pressure of less than orr.

According to the method of the present invention, mechanical impurities such as machine oil and fats from the human body adsorbed on the surface of plastic substrates are decomposed by the high energy of ultraviolet rays and strong oxidation of ozone generated by ultraviolet rays. The synergistic effect of this action and the sputtering action of the ion beam allows extremely efficient decomposition and removal. Further, impurities made of inorganic substances can be removed by sputtering action of an ion beam. Furthermore, it is also possible to activate the surface by cleaving the chemical bonds of molecules constituting the surface of the plastic substrate using high-energy ultraviolet rays and generating functional groups such as carbonyl groups and carboxyl groups in the cut molecular chains.

Furthermore, when ultraviolet rays and ion beams are irradiated during vapor deposition, the high energy of the ultraviolet rays and moderate ion bombardment from the ion beam combine to amplify the mobility of the evaporated particles on the substrate surface, resulting in crystalline growth. Not only does it have an effective effect on the initial process of film formation, but it can also promote the formation of a dense film by removing weak bonds and reworking structures with many defects during the entire process of film formation. .

Therefore, according to the present invention, it is possible not only to remove impurities that prevent healthy film formation from the surface of a plastic substrate, but also to activate the plastic substrate, so that irrespective of the type of evaporation material, it is possible to remove evaporation particles from the substrate. The bonding strength of the plastic substrate increases, and a healthy and dense film is formed, resulting in excellent adhesion and durability between the plastic substrate and the film.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an apparatus (vacuum evaporation apparatus) 1 used for carrying out the method of forming films on plastics 1 and plates according to the present invention.

In FIG. 1, reference numeral 2 denotes a plastic substrate on which a thin film is to be deposited, and in the illustrated example (first embodiment), it is a molded acrylic lens. This acrylic lens 2 is attached to a rotating dome 4 placed in a vacuum deposition chamber 3 in a vacuum deposition apparatus 1. 5 is a vapor deposition material, and MgF is used in the first embodiment. 6 is an electron gun for heating and vaporizing the vapor deposition material 5; 7 is a low-pressure mercury lamp, which can irradiate the entire surface of the dome 4 with ultraviolet rays. Reference numeral 8 denotes an ion gun, which can irradiate the entire surface of the dome 4 with an ion beam. Reference numeral 9 denotes an electron gun (hereinafter referred to as a neutralizer) that generates an electron beam to electrically neutralize the ion beam irradiated from the ion gun 8 and prevent char shear and damage to the insulating substrate.
).

Next, a method for forming a thin film of MgP on the acrylic lens 2 using the apparatus 1 shown in FIG. 1 will be described.

First, the acrylic lens 2 is attached to the rotating dome 4, and the low-pressure mercury lamp 7 is turned on. The ultraviolet rays generated from the low-pressure mercury lamp 7 are diffused and irradiate the entire surface of the rotating dome 4 and the entire inner wall of the vacuum deposition chamber 3. Three low-pressure mercury lamps 7 are installed in the vacuum evaporation chamber 3, each with an output of 5.
It is 00W.

After lighting these low-pressure mercury lamps 7 for one minute or more, the inside of the vacuum browning chamber 3 is evacuated. When the degree of vacuum in the vacuum deposition chamber becomes less than IXl0-5 Torr, the low-pressure mercury lamp 7 is turned off.

After irradiation with the low-pressure mercury lamp 7, when the degree of vacuum in the vacuum evaporation chamber 3 becomes less than I x 10-5 Torr, the low-pressure mercury lamp 7 is turned on again, and at the same time, the ion beam is emitted from the ion gun 8 and the neutralizer 9 irradiate each with a neutralizing electron beam for at least 1 minute. The ion beam generated from the ion gun 8 is diffusely irradiated onto the entire surface of the rotating dome 4.

The ion gun 8 is a hot cathode electron surface 11 (Kaufman) type, and uses Ar gas as an ion source. Further, the ion acceleration voltage is set to 500 V or less, the acceleration current is set to 60 mA or less, and the current density on the surface of the acrylic lens 2 is adjusted to be 7.5 #A/c4 or less. The 1tfL value of the neutralizer 9 is set to 5A or more so that the surface of the acrylic lens 2 is not charged up.

After irradiating ultraviolet rays and ion beams in this manner, a vapor deposition material 5 of MgF is vapor-deposited on the surface of the acrylic lens 2 by an electron beam vapor deposition method using an electron gun 6 to form a film.

MgFz on the acrylic lens 2 formed by the above process
In order to investigate the performance of 11, scratch tests and tape peeling tests were conducted on the MgF film-formed surface, and it was confirmed that it was sufficiently durable for practical use. Furthermore, after carrying out a 200 hour durability test under various conditions of -30°C to 80°C, no problems occurred even when the same tests as above were carried out.

The mechanism that produces this effect will be explained in detail below.

First, by lighting the low-pressure mercury lamp 7 in the atmosphere and irradiating the acrylic lens 2 with ultraviolet rays, organic impurities adhering to the surface of the acrylic lens 2 are directly decomposed or activated to easily cause oxidation, and at the same time, the ultraviolet rays The oxidizing action of activated oxygen (0) separated from the ozone (0,) generated by the action decomposes organic impurities into simple molecules such as H, O, Co, No. 8, etc. Although some of these organic impurities reduced in molecular weight are removed in the subsequent exhaust process, most of the remaining impurities remain on the surface of the acrylic lens 2. Next, by irradiating with an ion beam in a vacuum, the sputtering action of ions occurs, completely removing organic impurities that have become low molecular weight and remain on the surface of the acrylic lens 2, as well as organic impurities that cannot be removed by the action of ultraviolet light. do.

Furthermore, the ultraviolet rays that are irradiated simultaneously with the ion beam in a vacuum are absorbed by the 0□ and reach the substrate much more easily, and since impurities on the substrate surface are completely removed, they can effectively act on the substrate. The chemical bonds on the surface of the acrylic substrate are cut, and carbonyl groups, carboxyl groups, etc. are generated in the cut molecular chains, modifying the surface to be highly polar. As mentioned above, when a plastic substrate is irradiated with ultraviolet rays and an ion beam before vapor deposition, it has a cleaning effect that completely removes impurities (organic and inorganic substances) on the surface of the plastic substrate, and activates the surface of the plastic substrate, turning it into a highly polar surface. A surface modification effect is achieved at the same time.

Therefore, according to the film forming method of the first embodiment, it is possible to form a film having high adhesion and high durability sufficient for practical use.

In the second embodiment of the present invention, Si is used as the vapor deposition material 5.
O! and two low-pressure mercury lamps (5
00W) and one xenon short arc lamp (10
0OW) is used. As a pretreatment for depositing SiO□,
A low-pressure mercury lamp and a short arc lamp are turned on to irradiate ultraviolet rays and an ion beam from an ion gun under the same conditions as in the first embodiment. After that, the two acrylic lenses S]0. is deposited using electron beam evaporation.

The membrane of this example was tested for durability using the same test method as in the first example, and the same results as in the first example were obtained.

In the third embodiment of the present invention, under the same conditions as in the first embodiment, ultraviolet rays are irradiated from the low-pressure mercury lamp 7 and ion beams are irradiated from the ion gun 8 before vapor deposition, and the irradiation is continued during vapor deposition, so-called assist. An acrylic lens is used as the plastic substrate on which the vapor deposition is performed, and A]z03. as the vapor deposition material 5. ZrOlMgF, thereby 1
The layer is AhOt, the second layer is Zr0. 3rd layer force <MgF
An antireflection film having a three-layer structure consisting of , is formed by electron beam evaporation.

The optical properties of the film obtained in this example showed a reflectance of 0.8% or less at wavelengths of 450 to 650 nm, which was at the same level as the film on a glass lens. In addition, in terms of durability in scratch tests, tape peel tests, etc., although it is a multilayer film, the results showed that it was sufficiently durable for practical use, similar to the first example.

The result in the third example was that the synergistic effect of the surface cleaning effect and the surface modification effect similar to that in the first example was combined with the high energy of ultraviolet rays and moderate ion bombardment by the ion beam. It not only effectively acts on the initial process of film formation by amplifying the mobility at the top and promoting nuclear growth, but also removes weak bonds and attacks structures with many defects during the entire process of film formation. This is based on the extremely large assisting effect of promoting the formation of a dense film through the healing action. Therefore, according to the film forming method for the cough example, it is possible to form a film having high adhesion and high durability that is sufficient for practical use.

In the fourth embodiment of the present invention, ultraviolet rays are emitted from the low-pressure mercury lamp 7 before and during film formation under the same conditions as in the third embodiment.
The ion beams are irradiated from the ion gun 8, and in addition, from just before the film formation to during the film formation, a gas of 1 and 0 is applied.
Assisted vapor deposition is performed by introducing at a low partial pressure of x 10-5 Torr or less. In this example, SiO□ is formed as the first layer,
After that, apply 5ift to odd-numbered layers and T10 to even-numbered layers. A half mirror having a film structure of six layers in total is formed by vapor deposition.

The optical properties of the film of this example are the same as those formed on a normal glass substrate, and there is almost no change in properties (ie, wavelength knot) after the durability test. In addition, regarding durability by scratch tests, tape peel tests, etc., both initial performance and durability performance are similar to those of the above-mentioned examples, and results sufficient for practical use are obtained.

These results show that in addition to the same effects as in the third embodiment, 02
This is because the introduction of gas promotes the generation of ozone (0,), particularly enhances the effect of decomposing and removing organic impurities, and the 0 layer molecules act on film formation to relieve internal stress.

Next, in order to compare the effects of the present invention, p was vapor-deposited on the acrylic lens 2 in the same manner as in the first example without using the low-pressure mercury lamp 7 and the ion gun 8. When the durability of the film thus obtained was examined in the same manner as in the first example, scratches and peeling occurred in the film in the scratch test and tape peel test.

3 Effects of the Invention] As described above, according to the film forming method of the present invention, impurities are removed from the surface of the plasti/response substrate and the plastics/response substrate is activated or modified. The bonding force of the particles to the substrate is increased without any distortion, and a healthy and dense film is formed, resulting in excellent adhesion and durability between the plastic substrate and the film. As a result, 1
Regardless of the 111th vapor deposition material, it is possible to form a film on a plastic substrate that has the same high adhesion and durability as a film formed on a glass material.

[Brief explanation of drawings]

The figure is an explanatory diagram of an apparatus used to carry out the method of the present invention. ■...Vacuum evaporation device 2...Plastic substrate 3...Vacuum evaporation chamber 4...Rotating dome 5...Evaporation material 6...Electron gun 7...Low pressure mercury lamp 8...Ion gun 9... Neutralizer

Claims (2)

[Claims] (1) A method for forming a film on a plastic substrate, which comprises irradiating the surface of the plastic substrate with ultraviolet rays and an ion beam before or during the vapor deposition when forming a film on the plastic substrate by vacuum evaporation. (2) Irradiation with the ultraviolet rays and ion beam at O_2
2. The method of forming a film on a plastic substrate according to claim 1, wherein the gas is introduced into the deposition chamber at a low partial pressure of 1×10^-^5 Torr or less.