JPH04181902A - Antireflection film to optical parts made of synthetic resin - Google Patents

Abstract

PURPOSE:To provide the antireflection film which has a high adhesive property to a synthetic resin, is less deteriorated in the adhesive property of the film even after a moisture resistance test and less absorbs light by interposing a mixture composed of ZrO2 and TiO2 or a mixture composed of the ZrO2 and Ta2O5 as the tight adhesive layer to the synthetic resin. CONSTITUTION:The antireflection film provided on the surface of a synthetic resin substrate is constituted, successively from a front surface side to an air side, of a 1st layer consisting of the mixture composed of the zirconium oxide (ZrO2) and the titanium oxide (TiO2) or the mixture composed of the zirconium oxide (ZrO2) and the tantalum oxide (Ta2O5) and the 2nd layer consisting of the silicon dioxide (SiO2). These mixture layers have the high adhesive property equal to the adhesive property of CeO2 to the synthetic resin. In addition, the layers are stable, less change with lapse of time and has high productivity. Further, the packing ratio (the degree of the density of the film) of the mixture layers is higher than the packing ratio of CeO2 and since the mixture layers are hardly affected by the influence of the moisture and, therefore, the moisture resistance is improved. The mixture layers have the lower absorption in a short wavelength region of <=420nm than CeO2 and do not hinder the color balance of transmitted light.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an antireflection coating for optical components made of synthetic resin.

[Prior Art] In recent years, synthetic resins, which are lightweight and easy to process, have been increasingly used as materials for optical components such as lenses, instead of inorganic glass. However, similar to those made of inorganic glass, this synthetic resin optical component has a problem in that it reflects a large amount of light and is soft, so its surface is easily damaged. For this reason, it is necessary to apply an antireflection film that also serves as protection against curing to optical components made of synthetic resin.

Generally, anti-reflection coatings are formed by vacuum evaporation, and in the case of inorganic glass, the inorganic glass can be vapor-deposited by heating, so the adhesion between the inorganic glass and the vapor-deposited film is good (strong It is possible to form a film.However, since
In the case of synthetic resins, because the thermal deformation temperature of synthetic resins is low, it is not possible to heat the substrate in the same way as with inorganic glass, which leads to poor adhesion between the synthetic resin and the deposited film, resulting in poor durability. .

Therefore, in the past, an antireflection film was formed in which -silicon oxide (Sill) was interposed as an adhesion layer with a synthetic resin, as disclosed in, for example, JP-A-60-130701 and JP-A-60-130704. It is known that SiO is used as an adhesive layer because it has high adhesion to synthetic resins. However, SiO is known to be an unstable substance and Since the refractive index changes greatly over time, there is a problem that the reflectance characteristics lack stability.Also, SiO is a substance that can only be deposited stably by resistance heating evaporation; There were also cost problems in production due to poor productivity and high running costs.

In order to solve the above problems, Japanese Patent Laid-Open No. 63-8
As disclosed in Japanese Patent No. 1404, cerium dioxide (
An antireflection film in which CeO□) is interposed to improve adhesion to a synthetic resin has been proposed.

Ce02 is a material with many advantages such as high adhesion with synthetic resins, stable refractive index, little change over time, and high productivity as it can be deposited by electron beam heating vapor deposition. It was found that they have the following interstitial fat and ton.

[Problems to be Solved by the Invention] Firstly, CeO□ tends to form a film with a low filling rate (porous film). ℃, 95%, 300 hours), moisture penetrates into the Ce02 film, and the Ce02
This will affect the interface between O2 and the deposited film layered thereon. As a result, there was a problem in that the adhesion between the films constituting the antireflection film was extremely deteriorated, and the tape easily peeled off.

Secondly, CeO2 absorbs light in a short wavelength region of 420 nm or less, and if CeO2 is used in an antireflection film for a camera ticking lens or the like, there is a risk that the color balance of transmitted light may be disrupted.

The present invention has been made in view of these conventional problems, and has the advantages of high adhesion to synthetic resins, stability, and high productivity, while preventing deterioration of film adhesion even after a temperature resistance test. The purpose of the present invention is to provide an antireflection coating for synthetic resin optical parts that has no reflection and has low absorption.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an antireflection film provided on the surface of a synthetic resin substrate, which is coated with zirconium oxide (2rO□) in order from the surface side to the air side. Titanium oxide (
TiO□) or zirconium oxide (2rO=
) and tantalum oxide (Ta2os), and a second layer made of silicon dioxide (S 102 ).

In the present invention, examples of synthetic resins forming optical components include acrylic resin (PMMA), polycarbonate resin (PC), polystyrene resin (PS), amorphous polyolefin resin fAPO), and ultraviolet light fU.
Any material such as Vl curable resin may be used.

[Function] In the antireflection film for synthetic resin optical components having such a structure, the first layer is a mixture of 2rL and TiO□ or Zr0z.
A mixture of Ta205 and Ta205 is formed by electron beam heating evaporation. These mixture layers are composed of CeO and synthetic resin.
It has high adhesion similar to No. 2, is stable, has little change over time, and has high productivity.

Furthermore, as a feature of the present invention, the filling rate (degree of denseness of the film) of the mixture layer is higher than that of CeO□, and it is less affected by moisture (so that moisture resistance is improved).

Furthermore, the mixture layer has less absorption in the short wavelength region of 420 nm or less than CeO□, and does not impede the color balance of transmitted light.

These mixture layers have a higher refractive index (1,
85 to 2.10), which improves the antireflection effect. Note that the refractive index can be adjusted by changing the mixing ratio of the above mixture, and desired reflection characteristics can be obtained.

The second layer is formed on the fourth layer and constitutes the outermost layer of the antireflection film of the present invention, and is formed by forming 5102 by electron beam heating vapor deposition. 5102 has a lower refractive index (1.45 to 1.47) than the first layer, which provides the basic antireflection effect, and since 5iO7 is hard, it also acts as a surface protector. do.

The thickness of each layer of the first layer and the second layer of the antireflection film of the present invention is set at a design center wavelength of 2. The first layer is 045-0.5
7. From the viewpoint of reflection characteristics, it is preferable to provide the second layer in a thickness of 0.20 to 0.28 mm.

[Example] A synthetic resin substrate with a diameter of 15 mm is placed in a chamber with a diameter of 800 m.
After setting 500 pieces in a vacuum evaporation apparatus of 1.0 m, the inside of the vacuum evaporation chamber was evacuated to a high vacuum of I.times.10.sup.-5 Tarr or less. A diffusion pump or cryopump with a cold trap was used for the exhaust system. Thereafter, without heating the synthetic resin substrate, an electron beam heating method is used to increase the deposition rate to 0.5 to 1. Onm/sec
Antireflection films having the film configurations shown in Tables 1 to 6 were deposited under the following conditions.

(Leaving space below) Table 1 (Example 1) λ = 500 nm Table 2 (Example 2) 500 nm Table 3 (Example 3)
) λ = 500 nm Table 4 (Example 4) l = 500 nm Table 5 (Example 5) λ = 500 nm Table 6 (Comparative Example 1) N = 500 nm The reflectance characteristics of the antireflection films of Examples 1 to 5 were Figure ~ 5th
Shown in the figure. The antireflection film of the present invention has a visible range (400 to 7
It has a good antireflection effect at 00nml.

Next, the antireflection films of Examples 1 to 5 and Comparative Example 1 were evaluated for adhesion to the substrate, moisture resistance, thermal shock resistance, and absorption characteristics using the following methods.

(11) Tightness: An adhesive tape (cellophane adhesive tape) with a width of 10 mm was attached to the antireflection film, and one end of the adhesive tape was instantly peeled off at an angle of 45°, and the peeling state of the film was observed.

(2) Moisture resistance: 300°C in an environment with a temperature of 45°C and a humidity of 95%
After standing for a period of time, appearance performance and adhesion were evaluated using the method described in (1) above.

(3) Thermal shock resistance: After performing 10 cycles of leaving the sample in environments with temperatures of 130°C and 70°C for 30 minutes each, appearance performance and adhesion were evaluated using the method described in (1) above.

(4) Absorption characteristics: Measure the spectral transmittance and spectral reflectance of a substrate with an anti-reflection film on one side using a spectrophotometer, and then subtract the absorption rate of the substrate from the absorption characteristics obtained to prevent reflection. The absorption properties of the membrane were evaluated (particularly the absorption rate at 400 nm).

The results of evaluating the adhesion, moisture resistance, impact resistance, and absorption properties of the antireflection films of Examples 1 to 5 and Comparative Example 1 are shown in Table 7.
As shown.

(Margins below) Table 7 ○: Good ×: Bad As can be seen from the results of Table 7, the antireflection film of the present invention:
It has the same performance as conventional anti-reflective films in terms of adhesion and thermal shock resistance, but is particularly superior to conventional anti-reflective films in terms of moisture resistance and absorption properties. In addition, the poor moisture resistance of Comparative Example 1 was due to tape peeling in all cases when an adhesion test was conducted after the above-mentioned moisture resistance test.

[Effects of the Invention] As described above, according to the antireflection coating for synthetic resin optical parts of the present invention, ZrO□ and Ti are used as an adhesive layer with the synthetic resin.
Since it contains a mixture of O□ or a mixture of 2rOz and Ta2es, it has high adhesion to synthetic resins, and even after a humidity test, there is no deterioration in the adhesion of the film, and there is little light absorption.

[Brief explanation of drawings]

1 to 5 are reflectance characteristic diagrams of Examples 1 to 5 of the antireflection film of the present invention, respectively. @Figure 1 Figure 2 X length (nm) Figure 3 Difference length (nm)

Claims (2)

[Claims] (1) Provided on the surface of a synthetic resin substrate, in order from the surface side to the air side, a first layer consisting of a mixture of zirconium oxide and titanium oxide or a mixture of zirconium oxide and tantalum oxide, and a second layer consisting of silicon dioxide. An antireflection coating for synthetic resin optical components, characterized by comprising: (2) 1.85≦n_1≦2.10 0.45λ≦n_
1d_1≦0.57λ1.45≦n_2≦1.47 0
．． 20λ≦n_2d_2≦0.28λ where, n_1; refractive index of the first layer n_1d_1; optical thickness of the first layer n_2; refractive index of the second layer n_2d_2; optical thickness of the second layer λ; center wavelength The antireflection film for synthetic resin optical parts according to claim 1, which satisfies the following conditions.