JPH04308801A - Plastic optical material - Google Patents

Abstract

PURPOSE:To provide the plastic optical material having multilayered antireflection films, good ray transmittability particularly in visible and UV regions and excellent durability. CONSTITUTION:This plastic optical material is constituted by forming the multilayered antireflection films on the surface of plastic consisting of an amorphous fluororesin. Of the multilayered antireflection films, the layer in contact with the plastic and the layer in contact with the outdoor air are constituted of SiO2 and the layer right under the SiO2 layer 2 in contact with the outdoor air is constituted of MgF2.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION The present invention relates to a plastic optical material having a multilayer anti-reflection coating, and more particularly to a plastic optical material having good light transmittance in the visible and ultraviolet regions and excellent durability.

0002

[Prior Art and Problems to be Solved by the Invention] 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, so it is difficult to create high-performance products. It is expected that it will become an industrial material that surpasses conventional inorganic glass optical materials.

The decisive factor in achieving high performance is optical transparency, and one is the use of anti-reflection coatings, which serve to reduce the reflection of light rays on the surface of plastic materials and make the light transmittance as high as possible. It's hanging. The biggest problem with this antireflection film coating technology 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. it is,
One reason is that fluororesins inherently have poor adhesion with other materials, so it has been considered difficult or impossible to form an antireflection film thereon. Another reason is that amorphous fluororesin is a new material that has recently appeared in the world.

[0005] Generally, the structure (material, film thickness) of an antireflection film
Candidate configurations can be selected by simulation using theoretical calculations. However, this ignores many practical factors such as interface problems, and therefore only provides guidelines for configuration selection. The problem of the interface between the plastic and the anti-reflection film, and in the case of multilayer anti-reflection films, the problem of the interface between each layer has a big impact, so in reality the only choice is to make selections based on the results of experimental trial and error. .

[0006] In Japanese Patent Application No. 2-228435, the inventors proposed that a layer in contact with plastic made of amorphous fluororesin be S
It has been disclosed that by using iO2 and MgF2 in the layer in contact with the outside air, it is possible to provide a plastic optical material that does not generate cracks and has good light transmittance. However, the MgF2 layer that is in contact with the outside air may not exhibit sufficient durability depending on the manufacturing conditions.

[0007]

[Means for Solving the Problems] In order to solve this problem, in addition to the combination of vapor deposition substances disclosed in Japanese Patent Application No. 2-228435, samples were prepared in which layers in contact with the outside air were vapor-deposited using various substances. I considered it. As a result, Si
It has been found that a layer in which O2 is exposed to the outside air exhibits excellent light transmittance and durability. The present invention has been made based on this knowledge.

That is, the present invention provides: (1) A plastic optical material in which a multilayer antireflection film is formed on the surface of a plastic made of an amorphous fluororesin, the layer of the multilayer antireflection film in contact with the plastic and the outside air. The layer in contact with the air is SiO2, and the layer in contact with the outside air is SiO2.
A plastic optical material characterized in that the layer immediately below the layer is composed of MgF2 (2) A plastic optical material in which an antireflection film consisting of five layers is formed on the surface of a plastic made of an amorphous fluororesin. The layer in contact with the plastic and the layer in contact with the outside air of the five-layer antireflection film are made of SiO2, and the layer in contact with the outside air is made of S.
A plastic optical material characterized in that the layer immediately below the iO2 layer is composed of MgF2 (3) A plastic optical material in which an antireflection film consisting of four layers is formed on the surface of a plastic made of an amorphous fluorine resin. The layer in contact with the plastic and the layer in contact with the outside air of the four-layer anti-reflection film are made of SiO2, and the layer in contact with the outside air is made of S.
A plastic optical material characterized in that the layer immediately below the iO2 layer is made of MgF2, and (4) item (1), (2) or (3) which is a pellicle material.
The present invention provides the following plastic optical materials.

As a first specific example of the present invention, there are the following four types of layer configurations. In addition, Pl. indicates a plastic made of amorphous fluororesin. ■SiO2 /MgF2 /ZrO2 /Y2 O3
/SiO2 /Pl. ■SiO2 /MgF2 /Y2
O3 /MgO/SiO2 /Pl. ■SiO2/
MgF2 /ZrO2 /MgO/SiO2 /Pl.
■SiO2 /MgF2 /ZrO2 /PbF2 /
SiO2/Pl. Among these, the former three are more preferable.

In the present invention, the SiO2 layer in contact with the plastic in the multilayer anti-reflection film has the function of improving the adhesion between the amorphous fluororesin and the upper layer and preventing the occurrence of cracks. It is thought that the layer has the effect of improving wear resistance and moisture resistance.

FIG. 1 is a cross-sectional view showing an embodiment of the plastic optical material according to the present invention, in which 1 is an amorphous fluororesin having good transmittance in the visible and ultraviolet regions, and 2 is a fluorine-based resin. A first layer of antireflection film made of SiO2 is deposited on resin 1, and Y2 is deposited on first layer 2 of antireflection film 3.
4 is the second anti-reflection film layer made of O3.
A third anti-reflection coating made of ZrO2 deposited on layer 3.
Layer 5 is MgF2 deposited on the third layer 4 of the anti-reflection coating.
The fourth anti-reflection film layer 6 is a fifth anti-reflection film layer made of SiO2 deposited on the fourth anti-reflection film layer 5.

[0012] To form such an antireflection film on the surface of a plastic material, any method such as vacuum evaporation, ion plating, sputtering, or CVD may be used, but vacuum evaporation using an electron beam is preferable. Law is good. In such a vapor phase deposition method, the degree of vacuum of the apparatus is increased, the deposition rate is appropriately controlled, etc. as appropriate. In many cases, the same material as the material constituting the desired antireflection film is used as the raw material, and this is deposited on the plastic by vapor deposition or sputtering. In some cases, reaction precipitation may be performed using a raw material different from the constituent substances of the antireflection film.

In the present invention, ZrO2 refers to ZrO2
This term also refers to so-called stabilized zirconia containing Y2O3 in addition to itself and several mol% of Y2O3. In the present invention, it is preferred to use ZrO2 containing Y2O3 in most cases. 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 thickness of the SiO2 film in contact with the plastic is 60 to 100 nm, and the Y2 film thickness is 60 to 100 nm.
The film thickness of O3 is 40 to 80 nm, and the film thickness of ZrO2 is 40 to 80 nm.
0 to 80 nm, the thickness of MgF2 is 40 to 80 nm, the thickness of SiO2 in contact with the outside air is 10 to 40 nm, and in the case of the layer structure (2), the thickness of SiO2 in contact with plastic is 60 to 100 nm. , the film thickness of MgO is 40 to 80 nm, and the film thickness of Y2O3 is 40 to 80 nm.
By appropriately selecting the film thickness of m, MgF2 from 40 to 80 nm and the film thickness of SiO2 in contact with the outside air from the range of 10 to 40 nm, the so-called g-line (436 nm), i The transmittance at a wavelength of 365 nm can be increased to 95% or more, preferably 99% or more.

Other specific examples of the present invention include the following layer structure. ■SiO2 /MgF2 /PbF2 /SiO2 /
Pl. In this case as well, the SiO2 layer in contact with the plastic in the multilayer anti-reflection film has the effect of improving the adhesion between the amorphous fluororesin and the upper layer and preventing cracks from occurring, as in the specific examples ① to ② above. SiO2 exposed to outside air
It is thought that the layer has the effect of improving wear resistance and moisture resistance. On the other hand, the functions of the MgF2 layer and the PbF2 layer are similar to those in cases ① to ②. Further, the method for forming the antireflection film is the same as in the above-mentioned specific examples (1) to (2).

FIG. 2 is a cross-sectional view showing another embodiment of the plastic optical material according to the present invention, in which 11 is an amorphous fluororesin having good transmittance in the visible and ultraviolet regions, and 12 is a fluorine-based resin. A first anti-reflective film layer made of SiO2 is deposited on the resin 11, a second anti-reflective film layer 13 is made of PbF2 and is deposited on the first anti-reflective film layer 12, and 14 is a second anti-reflective film layer. A third anti-reflective layer 15 of MgF2 is deposited on layer 13, and a fourth anti-reflective layer 15 of SiO2 is deposited on third anti-reflective layer 14.

In this embodiment as well, the wavelength for which the anti-reflection film is particularly desired to be transmitted can be arbitrarily selected by setting the film thickness of the vapor-deposited material. In the case of the layer structure (2), the thickness of the SiO2 film in contact with the plastic is 60 to 10
0nm, PbF2 film thickness 30-60nm, MgF2
By appropriately selecting the film thickness of SiO2 in the range of 40 to 80 nm and the film thickness of SiO2 in contact with the outside air in the range of 10 to 40 nm, the
The transmittance in m) can be 95% or more, preferably 99% or more.

In the present invention, the above-mentioned multilayer antireflection film is formed on the surface of the amorphous fluororesin. This resin is, for example, a molded object such as a film, a sheet, a plate, a filament, a lens, or other irregular cross-sectional shape. An antireflection film is formed on a part or all of the surface of such a molded body. 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.

[0018] Examples of the fluororesin used in the present invention include the following.

[0019]

[Chemical formula 1]

(d) A copolymer of one or more of the monomers constituting (a), (b), and (c) above and another copolymerizable fluorine-containing monomer.

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

[0022]

[Case 2]

The fluororesin used in the present invention has, for example, the general formula

[Chemical formula 3] (However, n = 0 to 5, m = 0 to 5, m + n = 1 to 6.) dimethyl-1
, 3-dioxole by radical polymerization. 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 fluorovinyl ether. 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 having no crystals. This is because light transmission is not inhibited by microcrystals. In the present invention, particularly preferred fluororesins include, for example, Du Pon
Fluororesin “F” with a ring structure in the main chain manufactured by Company T
PX" or "Teflon AF" (product name) and fluororesin "CY" with a ring structure in the main chain manufactured by Asahi Glass Co., Ltd.
TOP” (product name), etc. can be exemplified.

The optical material of the present invention is, for example, as follows. Examples of molded bodies with irregular cross sections include optical lenses. It is useful for converging and scattering light from the visible to ultraviolet ranges. An example of a sheet-like member is a transparent window material for an ultraviolet irradiation device. It is lighter and more impact resistant than inorganic glass members, and has great industrial value. An example of a film-like member is a pellicle. A pellicle is a dust-proof protective cover for a photomask or reticle used in the photolithography process when manufacturing ultra-high density integrated circuits (so-called LSIs). 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 are i-line (365
The transmittance of short wavelength ultraviolet light (nm) or less was insufficient, which caused 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 a 450n
Excellent light transmittance in the short wavelength range of m or less. especially,
Its major feature is that it can simultaneously have high light transmittance of 99% or more at both i-line (365 nm) and g-line (436 nm) wavelengths.

[0027]

EXAMPLES Next, the present invention will be explained in more detail based on examples.

Example 1 As an amorphous fluororesin film, "CYTOP" (refractive index n=1.34) manufactured by Asahi Glass Co., Ltd. was used to prepare a 10 μm thick film by spin coating. An electron beam evaporator was used to deposit S as the first layer on both sides of the film.
The film thickness of iO2 is 70 nm, and Y2 O3 is used as the second layer.
The film thickness was 55 nm, and the third layer was 2 mol% Y2O3.
The thickness of the ZrO2 layer is 50 nm, and the fourth layer is Mg.
F2 was deposited to a thickness of 55 nm, and SiO2 was deposited as a fifth layer to a thickness of 15 nm.

FIG. 3 shows the transmittance characteristics of this plastic optical material for vertically incident light. The transmittance at 365 nm was 99.4%, and the transmittance at 436 nm was 99.4%. In addition, this plastic optical material was heated at 80℃ and 80℃.
%RH for 24 hours, there was no change in the transmission characteristics.

Example 2 As an amorphous fluororesin film, Du Pont
“Teflon AF1600” (refractive index n=1.31)
A sheet with a thickness of 1 mm was produced using an extrusion molding method. The first layer is coated on both sides of this sheet using an electron beam evaporator.
The film thickness of SiO2 is 90 nm as a layer, and the thickness of M as a second layer is 90 nm.
The thickness of gO is 65 nm, the thickness of Y2O3 as the third layer is 65 nm, and the thickness of MgF2 is 50 nm as the fourth layer.
20 nm thick SiO2 was deposited as the fifth layer.

FIG. 4 shows the transmittance characteristics of this plastic optical material for vertically incident light. The transmittance at 365 nm was 99.6%, and the transmittance at 436 nm was 99.6%. In addition, this plastic optical material was heated at 80℃ and 80℃.
%RH for 24 hours, there was no change in the transmission characteristics. In addition, a peel test was conducted by adhering 3M Scotch tape to the surface of this plastic optical material and pulling it quickly, but no peeling of the deposited film occurred.

Example 3 As an amorphous fluororesin film, Du Pont
“Teflon AF1600” (refractive index n=1.31)
A sheet with a thickness of 1 mm was produced using an extrusion molding method. The first layer is coated on both sides of this sheet using an electron beam evaporator.
The thickness of SiO2 layer is 75 nm, and the second layer is P.
The thickness of bF2 was 45 nm, the thickness of MgF2 was 55 nm as the third layer, and the thickness of SiO2 was 20 nm as the fourth layer.
m, respectively. FIG. 5 shows the transmittance characteristics of this plastic optical material for vertically incident light. 36
The transmittance at 5 nm was 99.4%, and the transmittance at 436 nm was 99.5%.

[0033] Also, this plastic optical material was heated to 80°C.
Although it was left for 24 hours in an environment of 80% RH, there was no change in the transmission characteristics. In addition, 3M Scotch tape was adhered to the surface of this plastic optical material.
A peel test was performed in which the film was pulled quickly, but no peeling of the deposited film occurred.

<Comparative Example> As an amorphous fluororesin film, "CYTOP" manufactured by Asahi Glass Co., Ltd. (refractive index n=1.34) was used.
) was used to prepare a 10 μm thick film by spin coating. Using an electron beam evaporation device, the film was coated on both sides of this film with a thickness of 75 nm of SiO2 as the first layer, a thickness of 55 nm of Y2O3 as the second layer, and a thickness of ZrO2 containing 2 mol% Y2O3 as the third layer. 50
A fourth layer of MgF2 was deposited to a thickness of 70 nm.

When the transmittance characteristics of this plastic optical material for vertically incident light were measured, the transmittance at 365 nm was 99.5%, and the transmittance at 436 nm was 99.4%.
However, when the transmittance characteristics were remeasured after being left in an environment of 80°C and 80% RH for 24 hours, the transmittance at 365 nm was 94.3% and the transmittance at 436 nm was 93.8%.
It was getting worse.

[0036]

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 excellent transmission characteristics. , excellent adhesion and durability.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a plastic optical material according to the present invention.

FIG. 2 is a side view of another example of the plastic optical material.

FIG. 3 is a graph showing the transmittance characteristics of Example 1 with respect to vertically incident light.

FIG. 4 is a graph showing transmittance characteristics for vertically incident light in Example 2.

FIG. 5 is a graph showing transmittance characteristics for vertically incident light in Example 3.

[Explanation of symbols]

1, 11 Amorphous fluororesin film with good transmittance in visible and ultraviolet regions 2, 12 SiO2 layer 3 Y2 O3 layer 4
ZrO2 layer 5, 14 MgF2 layer 6, 15 SiO2 layer 13 PbF2 layer

Claims (4)

[Claims] 1. A plastic optical material in which a multilayer antireflection film is formed on the surface of a plastic made of an amorphous fluororesin, wherein the layer in contact with the plastic and the layer in contact with the outside air of the multilayer antireflection film are made of SiO2, A plastic optical material characterized in that a layer immediately below the SiO2 layer that is in contact with the outside air is made of MgF2. 2. A plastic optical material in which a five-layer antireflection film is formed on the surface of a plastic made of an amorphous fluororesin, wherein the layer of the five-layer antireflection film that is in contact with the plastic is in contact with the outside air. A plastic optical material characterized in that the layer is made of SiO2, and the layer directly under the SiO2 layer in contact with the outside air is made of MgF2. 3. A plastic optical material in which a four-layer antireflection film is formed on the surface of a plastic made of an amorphous fluororesin, the layer of the four-layer antireflection film in contact with the plastic being in contact with the outside air. A plastic optical material characterized in that the layer is made of SiO2, and the layer directly below the SiO2 layer in contact with the outside air is made of MgF2. [Claim 4] Claims (1) and (2) which are pellicle materials.
) or the plastic optical material described in (3).