JPH04153601A - Optical material made of plastic - Google Patents

Abstract

PURPOSE:To improve a transmission characteristic, adhesive property and durability by forming antireflection films consisting of 4 layers on the surface of plastic consisting of an amorphous fluororesin and forming the layer in contact with the plastic of the 4-layered antireflection films and the layer in contact with the outdoor air of SiO2. CONSTITUTION:This optical material is constituted of the amorphous fluororesin 1 having the good transmittance in visible and UV regions, the 1st layer 2 of the antireflection film consisting of the SiO2 deposited on the fluororesin 1, the 2nd layer 3 of the antireflection film consisting of MgO deposited on the 1st layer 2 of the antireflection film, the 3rd layer 4 of the antireflection film consisting of ZrO2 deposited on the 2nd layer 3 of the antireflection film, and the 4th layer 5 of the antireflection film consisting of the SiO2 deposited on the 3rd layer 4 of the antireflection film. The SiO2 layer in contact with the plastic in the multilayered antireflection films improves the adhesive property of the amorphous fluororesin and the upper layer and to prevent the generation of cracks therein. The SiO2 layer in contact with the outdoor air improves wear resistance and moisture resistance. The transmission characteristic, adhesive property and durability are improved in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a plastic optical material having a multilayer antireflection film, and particularly to a plastic optical material having good light transmittance in the visible and ultraviolet regions.

(Prior art and its problems) Plastic optical materials such as plastic lenses, plastic filters, and plastic window materials are lightweight, have excellent impact resistance, and are easy to mass produce. It is expected that it will occupy a position as an industrial material that surpasses glass optical materials.

The key to high performance is optical transparency, and one factor is the anti-reflection coating, which reduces the reflection of light rays on the surface of the plastic material and increases the light transmittance as much as possible. .

The biggest problem with this antireflection film coating technique is that cracks occur in the antireflection film coated on the surface of the plastic material, making it impossible to achieve the desired transmittance. This problem was particularly noticeable when the plastic was a thin film, or when it was made of olefin or fluorine resin.

Possible causes of this cracking include low adhesion between the plastic material and the material constituting the anti-reflection film and a large difference in coefficient of thermal expansion, but basically it is a problem at the interface. The problem is not simple.

In particular, there have been no examples of forming a high-performance antireflection film on an amorphous fluororesin material. That is, for one thing,
This is because fluororesins inherently have poor adhesion with other materials, so it was considered difficult or impossible to form an antireflection film thereon. Furthermore, this is because amorphous fluororesin is a new material that has recently appeared in the world.

Generally, the configuration (material, film thickness) of an antireflection film can be simulated through theoretical calculations to select candidate configurations. However, this ignores many realistic factors such as interface issues, and only provides guidelines for composition selection. In some cases, the problem of the interface between each layer has a great influence, so in reality the only choice is to make a selection based on the results of experimental trial and error.

The present invention creates a plastic optical material with excellent transmission characteristics, adhesion, and durability by forming a high-performance antireflection film on an amorphous fluororesin that has good transparency in the visible and ultraviolet regions. The purpose is to provide.

(Means for solving the problem) Conventionally, it has been said that fluororesins have poor adhesion with other substances, and although there were no guidelines available, we dared to make samples of various vapor deposition substances. We investigated adhesion and transparency. As a result, we unexpectedly found that 5iOa is suitable as a material for the first layer on the resin. We also investigated various combinations of evaporated materials that have antireflection effects. l) On top of this 5iOz, [Z r Oz
,y,Ox,MgO1AI2. Two layers are formed with a material selected from O, ], and on top of that, a material selected from Sin.

2) Forming one layer of y and o on the first layer of 5ins on the resin is excellent. On top of that, Sin
It was discovered that an antireflection film having a three-layer structure formed by forming layers consisting of the following is superior. The present invention was developed based on this knowledge.

That is, the present invention provides: (1) A plastic optical material in which a four-layer anti-reflection film is formed on the surface of a plastic made of an amorphous fluororesin, and a layer of the four-layer anti-reflection film that is in contact with the plastic. (2) A plastic optical material characterized in that a layer in contact with outside air is formed by Sing; (3) A plastic optical material according to item (1) or (2), which is a pellicle material, wherein the layer in contact with the plastic and the layer in contact with the outside air of the three-layer antireflection film are made of Stow. The present invention provides plastic optical materials.

One embodiment of the present invention includes the following four types of layer configurations.

■S i Ox /Zr0t /MgO/S i Ox
■SiO,/Y□0. /Aε, O, /SiO.

■S i Oz / Z r Oz / Y z Os
／ S i Oz■SiO□／ Y x Oz /
M g O/S i O2 Among these, the former three are preferred.

In the present invention, the Sin layer in contact with the plastic in the multilayer antireflection film has the effect of improving the adhesion between the amorphous fluororesin and the upper layer and preventing the occurrence of cracks,
It is thought that the SiO□ layer in contact with the outside air has the effect of improving wear resistance and moisture resistance.

FIG. 1 is a sectional view showing the layer structure of one embodiment of the plastic optical material according to the present invention, in which numeral 1 indicates an amorphous fluororesin having good transmittance in the visible and ultraviolet regions; 2
3 is a first layer of antireflection film made of 5ins deposited on fluororesin 1, 3 is a second layer of antireflection film made of MgO deposited on first layer 2 of antireflection film, and 4 is an antireflection film. Membrane 2
A third anti-reflective layer of ZrO□ is deposited on layer 3, and a fourth anti-reflective layer of SiO□ is deposited on third anti-reflective layer 4.

To form such an antireflection film on the surface of a plastic material, any method such as a vacuum evaporation method, an ion blating method, a sputtering method, or a CVD method may be used, but a vacuum evaporation method using an electron beam is preferably used. In this type of vapor phase deposition method, it is necessary to accumulate a lot of ingenuity and know-how, such as increasing the degree of vacuum in the equipment and controlling the deposition rate appropriately.In many cases, the raw material is , the desired anti-reflective film is composed of a substance and the like, and this is deposited on the plastic by vapor deposition or sputtering.In some cases, a different raw material from the constituent material of the anti-reflective film may be used for reaction deposition. be.

In the present invention, ZrO* also means so-called stabilized zirconia containing ZrO□ itself and several mo1% of Y*Os.

The wavelength for which the anti-reflection film should transmit particularly well can be arbitrarily selected by setting the film thickness of the vapor-deposited material. In the case of the layer structure mentioned above, the film thickness of 510 m is 60 to 120 nm.
m, the film thickness of MgO is 40 to 80 nm, and the film thickness of ZrO* is 40 to 80 nm.

The film thickness of 5iO= is within the range of 40 to 80 nm, and in the case of the layer structure of (■), the film thickness of 5ins is 60 to 120
nm, the film thickness of Ant Os is 50 to 90 nm,
By appropriately selecting the film thickness of YzOs in the range of 40 to 80 nm and the film thickness of SiOz in the range of 50 to 90nm, it is possible to achieve the so-called G-line (436mm) and I-line, which are expected to be used more in the future. (365nm) transmittance of 95
% or more, preferably 99% or more.

In another embodiment of the present invention, the layer structure may be three layers. This layer structure is shown in cross-section in FIG.

In the figure, 11 is an amorphous fluororesin with good transmittance in the visible and ultraviolet regions, and 12 is a Sin coated on the fluororesin II.
, 13 is a first layer of anti-reflection film 13 consisting of Y, 0. The second anti-reflection film layer 14 is made of Si deposited on the second anti-reflection film layer 13.
This is the third layer of the antireflection film made of O*. In this case, the function of each antireflection film, its formation method, etc. are the same as in the first embodiment.

In the case of the layer structure of the embodiment shown in FIG.
By appropriately selecting the film thickness of 20 to 800 m and the thickness of SiO
436mm), transmittance of i-line (365nm) to 95%
The ratio can be preferably increased to 99% or more.

In the eighth aspect of the present invention, the multilayer antireflection film described above is formed on the surface of an amorphous fluororesin. This resin is a molded object such as a film, a sheet, a plate, a filament, a lens, etc. with an irregular cross section.The anti-reflection coating is applied to a part or all of the surface of such a molded object. is formed. When there are clearly two surfaces, such as films, sheets, plates, lenses, etc., both surfaces are often coated together with an antireflection coating. The point is related to how the optical member is used, and the above-mentioned antireflection film is formed on all the interfaces of the resin molded body in the path through which the light rays pass.

In the present invention, examples of the fluororesin used include the following.

(a) (b) (C) (d) One or more of the monomers constituting the above (a), (b), and (c) and another copolymerizable fluorine-containing monomer; Copolymer of.

Among these, the following fluororesins having a ring structure in their main chain are representative.

Copolymer.

Used in the present invention. For example, the fluororesin has the general formula % (where n = O ~ 5, m = O ~ 5, and m + n = 1 ~
It is 6. ) is obtained by radical polymerization of perfluoroether or perfluoro-2,2-dimethyl-1,3-dioxole having two terminal double bonds. Further, the copolymer can be obtained by copolymerizing the above-mentioned perfluoroether or perfluoro-2,2-dimethyl-1,3-dioxole with a fluorine-containing monomer such as fluoroolefin or fluorovinylether. Examples of the monomer include tetrafluoroethylene, perfluorovinyl ether, vinylidene fluoride, and chlorotrifluoroethylene.

The resin used in the present invention is a so-called amorphous resin that does not have crystals. This is because light transmission is not inhibited by microcrystals.

Particularly preferred fluororesins in the present invention include, for example, the fluororesin rFPXJ, which has a ring structure in the main chain manufactured by Du Pont Company, or the fluororesin rFPXJ, which has a ring structure in the main chain manufactured by Teflon AFJ (trade name), and Asahi Glass ■. Examples include fluororesin rcYTOPJ (trade name), which has

The optical material of the present invention is, for example, as follows. Examples of molded bodies with irregular cross-sections include optical lenses for use in cargo applications to converge and disperse light rays from the visible range to the ultraviolet range. An example of a sheet-like member is a transparent window material for an ultraviolet irradiation device. A pellicle is an example of a film-like member that is lighter than inorganic glass members, has impact resistance, and has great industrial value. Pellicle is an ultra-high density integrated circuit called L
This is an integrated dustproof protective cover for a photomask or reticle used in the photolithography process when manufacturing SI. Conventional pellicles are made by forming an antireflection film on a cellulose film several microns thick, and attaching the film to a metal frame of a predetermined size without loosening. Cellulose-based pellicles do not have sufficient transparency in the short wavelength ultraviolet region below the i-line (365 nm), which poses a practical problem. A pellicle made of the member of the present invention replaces conventional pellicles.

The plastic optical material of the present invention has excellent light transmittance in a short wavelength region of 450 nm or less. In particular, the i-line (365
9 nm) and g-line (436 nm) wavelengths simultaneously.
It can have a high light transmittance of 9% or more, which is a major feature.

(Example) Examples of the present invention will be shown below.

Example 1 As an amorphous fluororesin, “Cytotsubu” manufactured by Asahi Glass Co., Ltd.
(refractive index n=1.34), a 15 μm thick film was produced by the spin code method. A first layer of SiO2 was deposited on both sides of the film using an electron beam evaporator.
The film thickness of MgO was 90 nm, and the film thickness of MgO was 60 nm as the second layer.
m, 2mo 1% Y20. as the third layer. The film thickness of the ZrO-containing layer was 65 nm, and the film thickness of 5iO- as the fourth layer was 65 nm.
m was deposited.

Figure 3 shows the transmittance characteristics of this plastic optical material for vertically incident light.The transmittance at 365 nm is 99.5.
%, and the transmittance at 436 nm was 99.6%.

In addition, this plastic optical material was
After being left for 1,000 hours, no change was observed in the transmission characteristics.

Example 2 A 1 mm thick sheet was produced by extrusion using Teflon AF1600J (refractive index n=1.31) manufactured by Du Pont as the amorphous fluororesin. Electron beam was applied on both sides of this sheet. Using a vapor deposition apparatus, the film thickness of SiO□ was 95 nm as the first layer and Aβ201 as the second layer.
The thickness of the third layer was 75 nm, and the thickness of Y2O was 65 nm as the third layer.
A fourth layer of SiO□ was deposited to a thickness of 65 nm.

FIG. 4 shows the transmittance characteristics of this plastic optical material for vertically incident light. Transmittance at 365nm is 99.5
%, and the transmittance at 436 nm was 99.5%.

In addition, this plastic optical material was
After being left for 1,000 hours, no change was observed in the transmission characteristics.

In addition, a beer test was carried out by adhering 3M Scotch tape to the surface of this plastic optical material and quickly pulling it, but no peeling of the deposited film occurred.

Example 3 As amorphous fluororesin, “Cytotsubu” manufactured by Asahi Glass Co., Ltd.
(refractive index n=1.34), a 15 μm thick film was produced by the spin code method. A first layer of S i O was deposited on both sides of this film using an electron beam evaporation device.
The film thickness of z is 80 nm, and the film thickness of Y, O, as the second layer is 3
5 nm, and a third layer of Sin was deposited to a thickness of 80 nm.

FIG. 5 shows the transmittance characteristics of this plastic optical material for vertically incident light. Transmittance at 365nm is 99.1
%, and the transmittance at 436 nm was 99.2%.

In addition, this plastic optical material was
After being left for 1,000 hours, no change was observed in the transmission characteristics.

(Effects of the Invention) As explained above, the plastic optical material of the present invention has an antireflection film that is compatible with an amorphous transparent fluororesin that has good transparency in the visible and ultraviolet regions, and has transmission characteristics. , adhesion,
and excellent durability.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the plastic optical material according to the present invention, FIG. 2 is a cross-sectional view showing another embodiment of the plastic optical material according to the present invention, and FIG. 3 is a cross-sectional view showing another embodiment of the plastic optical material according to the present invention.
FIG. 4 is a graph showing the transmittance characteristics of Example 2 with respect to vertically incident light, and FIG. 5 is a graph showing the transmittance characteristics of Example 3 with respect to vertically incident light. be. 1.11...Amorphous fluororesin with good transmittance in visible and ultraviolet regions, 2.12...SiO□ layer, 3...Mg
O layer, 4-Z r Os layer, 5.14...5iO1
Layer, 13...Y, O, layer.

Claims (3)

[Claims] (1) A plastic optical material in which a four-layer antireflection film is formed on the surface of a plastic made of amorphous fluororesin, and the four-layer antireflection film has a layer in contact with the plastic and a layer in contact with the outside air. A plastic optical material characterized by being made of SiO_2. (2) A plastic optical material in which a three-layer anti-reflection film is formed on the surface of a plastic made of amorphous fluororesin, the layer in contact with the plastic and the layer in contact with the outside air of the three-layer anti-reflection film. A plastic optical material characterized by being made of SiO_2. (3) The plastic optical material according to claim (1) or (2), which is a pellicle material.