JPH03132601A - Antireflection film of optical parts made of plastic and production thereof - Google Patents

Abstract

PURPOSE:To enhance the adhesion to optical parts made of plastics and to improve the durability and spectral reflection characteristics of the antireflection film by forming the film of a 3-layered structure of the 1st layer and 2nd layer consisting of silicon monoxide and the 3rd layer consisting of silicon dioxide. CONSTITUTION:The antireflection film is constituted on the surface of the optical parts made of the plastics by forming the vapor deposited films having the 3-layered structure of the 1st layer, the 2nd layer and the 3rd layer, succes sively from the front surface. The 1st layer and the 2nd layers 2, 3 are constitut ed of the silicon monoxide (SiO) and the 3rd layer 4 is constituted of the silicon dioxide (SiO2). The refractive index of the silicon monoxide of the 1st layer 2 is set smaller than the refractive index of the silicon monoxide of the 2nd layer 3. Thus, the antireflection film having the excellent adhesion to the plastic optical parts, durability, optical characteristics, and mass productivity is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an antireflection coating for plastic optical components used in optical systems such as projection televisions, video cameras, and still cameras, and a method for forming the antireflection coating.

Conventional technology Traditionally, inorganic glass has been widely used for optical parts such as lenses, but in recent years, plastics have been used as materials for optical parts because they are lightweight, easy to process, and suitable for mass production. It has come to be used. However, plastic optical components such as plastic lenses have the disadvantage that, similar to inorganic glass, light is highly reflected on the surface. In order to overcome this drawback, it is known as a general technique to form an anti-reflection film similar to that of inorganic glass on the surface of plastic optical components to prevent surface reflections (for example, "Seichu Plastic Optical Lens"). "Design, molding technology and its problems" Tricenops Materials Collection Nα87
P6-1 to P6-4).

Hereinafter, a conventional antireflection film for plastic optical components and a method for forming the same will be described with reference to the drawings. The single-layer anti-reflection film is made of magnesium fluoride (MgF2), whose structure is shown in Figure 2, and the plastic optical component is made of acrylic resin (polymethyl methacrylate) with a refractive index of 1.49. The spectral reflection characteristics when formed on the surface of an optical component are shown in FIG. 3(b). For comparison, FIG. 3(C) is a diagram showing the spectral reflection characteristics of a plastic optical component (made of polymethyl methacrylate) when no antireflection film is formed. In FIG. 2, 1 is a plastic optical component, and 5 is an antireflection film made of magnesium fluoride.

The anti-reflection film 5 is usually formed by a vacuum deposition method, but recently, in order to improve the adhesion and durability between the anti-reflection film and the surface of the plastic optical component, plastic optical components are heated at 60°C to 80°C. A method of forming an antireflection film using a method of heating to °C and vacuum deposition, and a method of forming an antireflection film using an RF ion blating method has been used. This anti-reflection film uses one type of vapor deposition material, but a film using two types of vapor deposition materials has a three-layer structure using silicon dioxide and magnesium fluoride (JP-A-6
0-129701) and cerium oxide (CeO2)
There is also an antireflection film made of 2FHA (Japanese Unexamined Patent Publication No. 172201/1983) made of silicon oxide (S i OX ) and silicon oxide (S i OX ).

Furthermore, as for those using three or more types of vapor deposition substances,
Anti-reflection coating with a three-layer structure of silicon dioxide, aluminum oxide (AI□08), and cerium oxide (Japanese Patent Application Laid-Open No. 63-814
Publication No. 02).

Problems to be Solved by the Invention In the example of forming an anti-reflective film made of magnesium fluoride by the vacuum deposition method, which is a conventional example of the anti-reflective film forming method described above, the flow temperature and heat distortion temperature of the plastic are low, and ,
Due to the problem of gases released from inside the plastic film, it is impossible to heat the substrate (usually 300°C to 400'C) when forming a deposited film on an inorganic glass substrate, making it impossible to obtain a strong deposited film. First, an anti-reflection film is formed on the surface of plastic optical components at a low temperature of 50°C to 60°C or less, but the anti-reflection film formed at this low temperature has poor adhesion to the plastic surface and has poor durability. is also low.

In addition, as mentioned above, the plastic optical components were heated to 60°C.
Anti-reflective coatings formed by heating to ~80°C or using the RF bio-ion blating method are prone to cracking.
Furthermore, it is difficult to maintain constant conditions during formation and to maintain a constant state of the plastic surface, and is not suitable for mass production. Furthermore, as shown in FIG. 3(b), the anti-reflection coating in the middle layer of magnesium fluoride has a center wavelength (λ
. ), the residual reflectance is about 1.5%, which does not have sufficient properties as an antireflection film for plastic optical parts.

Furthermore, the three-layer anti-reflection coating made of magnesium fluoride and silicon dioxide (Japanese Patent Application Laid-Open No. 129701/1989) does not cause cranking and has relatively good durability, but the residual reflectance is about the same as a single layer coating, so it does not have sufficient characteristics. do not have.

Furthermore, the two-layer antireflection film of cerium oxide and silicon oxide has a reliability problem because the thinly applied cerium oxide has poor chemical durability.

In addition, the use of three or more types of vapor deposition substances results in an increase in manufacturing costs due to the necessity of material management.

As mentioned above, conventional anti-reflection coatings for plastic optical components have poor adhesion to the plastic surface, poor durability, insufficient optical properties as an anti-reflection coating, poor chemical durability, or The problem was that it was not suitable for mass production.

In view of the above problems, the present invention provides an antireflection film that has excellent adhesion to plastic optical components, durability, optical properties, and mass productivity.

Means for Solving the Problems In order to solve the above problems, the present invention provides, on the surface of a plastic optical component, a first layer, a second layer,
The anti-reflection film is constructed by forming a three-layer adhesive film with a third layer, and the first and second layers are made of silicon monoxide, silicon monoxide, and a third layer.
The anti-reflective film is characterized in that the layer is made of silicon dioxide, and when forming the anti-reflective film having the 3+/= structure, the first layer of silicon monoxide is formed in an oxygen gas atmosphere. The present invention provides a method for forming an antireflection film.

Function The present invention has a three-layer structure on the surface of a plastic optical component, consisting of a first layer, a second layer, and a third layer in order from the surface side,
The first and second layers are made of silicon monoxide, and the third layer is made of silicon dioxide. Oxygen (02) gas is introduced when forming the first layer of silicon monoxide. By forming the silicon monoxide layer in an oxygen gas atmosphere, the refractive index of the first layer silicon monoxide can be controlled to be smaller than that of the second silicon monoxide layer, and the adhesion with plastic optical components can be improved. As a result, an antireflection film with excellent adhesion, durability, optical properties, and productivity can be obtained.

EXAMPLE Hereinafter, an antireflection film for a plastic optical component according to an example of the present invention and a method for forming the same will be described with reference to the drawings.

FIG. 1 is a diagram showing the structure of the antireflection film of the plastic optical component of the present invention, and FIG. 3(a) shows its spectral reflection characteristics. In this embodiment, the plastic optical component is an acrylic resin (polymethyl methacrylate) optical component. In Figure 1, ■ is a plastic optical component;
2.3 is a first layer and a second layer made of silicon monoxide, 4 is a third layer made of silicon dioxide, and the specific contents of the present invention are as shown in Table 1.

Table 1 (λ.=500 nm) The method of forming each layer is as follows. For the first layer, after evacuating the vacuum chamber to a vacuum level of 1.0 x 10 Torr, oxygen was removed to 1.0 x 10 Torr. Optical HUJ-λ of silicon monoxide was introduced up to OX 10' Torr. /4 (λ, ) = 500 nm) at a deposition rate of about 4 persons/sec. The refractive index of silicon monoxide at this time is 1.68. Next, the introduction of oxygen was stopped, and silicon monoxide was deposited to an optical thickness of λ under a vacuum of 1.5 x 10'1 iTorr. The film was formed at a deposition rate of about 10 persons/sec to a thickness of 1/4. The refractive index of -silicon oxide at this time is 1.90. Next, silicon dioxide is added and optical film thickness λ is determined. /4 thickness and deposition rate, about 10 people/see
It was formed with.

The tests conducted to confirm the adhesion and durability of the antireflection film of the above-mentioned examples of the present invention were as follows: (1) Adhesive tape peeling test (temperature: 40°C; relative temperature: 85%; high temperature;

After leaving it in a high temperature atmosphere for 1000 hours, stick the adhesive tape to the plastic optical component and peel it off), (
2) Humidity test (IJL degree 40" C1 relative humidity 95% high temperature, left in a high temperature atmosphere for 1000 hours) (3) Thermal shock test (temperature -30°C 970°C low temperature and high temperature atmosphere for 30 minutes alternately (4) Alcohol resistance test (immersion in ethyl alcohol solution for 10 minutes).The results of the adhesion and durability tests are shown in Table 2.

As can be seen from Table 2, the antireflection film of the present invention has excellent adhesion and durability. Furthermore, although in the past some cracks were observed during the formation of the antireflection film, in the examples of the present invention, the antireflection film was always stable. Regarding the spectral reflection characteristics, as can be seen from Figure 3 (a), the reflectance at the center wavelength (λo = 500 nm) is 0.5% or less, which is excellent as an anti-reflection property, and excellent characteristics can be obtained over a wide band. Ta.

In addition, in the above example, each film thickness was set as shown in Table 1, but the film thickness is not particularly limited to the above values,
It is only necessary to change it according to the design wavelength, and there is no problem as long as the structure is as shown in FIG.

Effects of the Invention As is clear from the above explanation, the antireflection coating of the plastic optical component of the present invention has a primary coating made of silicon oxide.
It has a three-layer structure: a first layer, a second layer, and a third layer made of silicon dioxide.Also, when forming the first layer of silicon monoxide, oxygen is introduced and the plastic is formed in an oxygen atmosphere. It improves adhesion to optical parts, improves the durability of the antireflection film, has excellent spectral reflection characteristics, prevents cracks, and has the effect of eliminating the drawbacks of conventional examples. Furthermore, the antireflection film for plastic optical components of the present invention is suitable for mass production, and therefore has great practical value.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the structure of the anti-reflection film of the plastic optical component of the present invention, Fig. 2 is a block diagram showing the structure of the anti-reflection film of the conventional plastic optical part, and Fig. 3 is the spectral reflection characteristics. This is a graph showing. Layer made of silicon oxide, 4... Layer made of silicon dioxide, 5... Layer made of magnesium fluoride, a... Plastic optical component in the embodiment of the present invention Characteristics of anti-reflection film of conventional plastic optical parts (single layer film made of magnesium fluoride), C: Characteristics of anti-reflection film of conventional plastic optical components, C... Characteristics of anti-reflection film of conventional plastic optical components No characteristics of plastic optical components.

Claims (3)

[Claims] (1) The surface of the plastic optical component has a three-layer structure of a first layer, a second layer, and a third layer in order from the surface side, and the first layer and the second layer are made of silicon monoxide (SiO). An antireflection film for plastic optical parts, characterized in that the third layer is made of silicon dioxide (SiO_2). (2) Claim characterized in that the refractive index of silicon monoxide in the first layer is smaller than the refractive index of silicon monoxide in the second layer
1) Antireflection coating for plastic optical components described above. (3) A method for forming an antireflection film for a plastic optical component, wherein the first silicon monoxide layer in the three-layer antireflection film is formed in an oxygen gas atmosphere.