JPH04128801A - Antireflection film to optical parts made of synthetic resin - Google Patents

Abstract

PURPOSE:To enhance the adhesive property to a synthetic resin and to improve productivity by constituting the above film, successively from a front surface side to an air side, of a 1st layer consisting of lanthanum fluoride or neodymium fluoride, a 2nd layer consisting of a mixture composed of zirconium oxide and titanium oxide or a mixture composed of ZrO2 and tantalum oxide and a 3rd layer consisting of silicon dioxide. CONSTITUTION:The 1st layer is formed of LaF3 or NdF3 by a vapor deposition method with electron beam heating. The 2nd layer is formed between the 1st layer and the 3rd layer and is formed of the mixture composed of the ZrO2 and TiO2 or the mixture composed of the ZrO2 and Ta2O5 by the vapor deposition method with electron beam heating. The 3rd layer is formed on the 2nd layer and is formed of the SiO2 by the vapor deposition method with electron beam heating. The respective layers from the 1st layer to the 3rd layer are so provided that the film thicknesses attain 0.16 to 0.34lambda of the 1st layer, 0.44 to 0.56lambda of the 2nd layer and 0.23 to 0.28lambda of the 3rd layer with respect to a design center wavelength lambda.

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, resulting in a strong film. It is possible to form however,
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, and as a result, the adhesion between the synthetic resin and the deposited film is poor, 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-60-257401 and JP-A-63-220101. The reason why SiO is used as the adhesive layer is that SiO has high adhesiveness to synthetic resins.

[Problem to be solved by the invention] However, SiO is known as an unstable substance,
Since the refractive index changes greatly over time, there is a problem in that the reflectance characteristics lack stability. Also, SiO
is a substance that can only be deposited stably using the resistance heating vapor deposition method, and the resistance heating vapor deposition method has poor productivity (running costs are also high, so there is also a problem in terms of production costs).

The present invention was made in view of such conventional problems, and an object of the present invention is to provide an antireflection coating for synthetic resin optical parts that has good adhesion to synthetic resin, is stable, and has high productivity. shall be.

[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 that is coated with lanthanum fluoride (LaF) in order from the surface side to the air side. Alternatively, a first layer consisting of neodymium fluoride (NdF), a second layer consisting of a mixture of zirconium oxide (ZrOzl and titanium oxide (T10□) or a mixture of ZrO□ and tantalum oxide (Tazos), and silicon dioxide (SiO □).

In the present invention, examples of synthetic resins for forming optical components include acrylic resin (PMMA), polycarbonate resin (PC), polystyrene resin (PS), amorphous polyolefin resin (APO), and ultraviolet 18 (U)
Any VI curable resin or the like may be used.

[Function] In the antireflection film for a synthetic resin optical component having such a structure, the first layer is formed of LaFs or NdFs by electron beam heating vapor deposition. LaF3 and NdF.

has high adhesion to synthetic resins, equivalent to that of SiO, and is more stable than SiO and exhibits less change over time (
Since it can be formed by electron beam heating vapor deposition, productivity is also high.

The second layer is formed between the first layer and the third layer, and is made of a mixture of Zr02 and TlO2 or a mixture of Zr0z and TaJs by electron beam heating evaporation. These mixture layers have a higher refractive index f1.85 than the first and third layers.
2.10), which improves the antireflection effect. Note that by changing the mixing ratio of the above mixture, the refractive index can be adjusted and desired reflection characteristics can be obtained.

The third layer is formed on the second layer and constitutes the outermost layer of the antireflection film of the present invention, and is formed of SiO□ by electron beam heating vapor deposition. 5102 has a lower refractive index [1.45 to 1.471] than the second layer, providing the basic properties of antireflection effect and
Since it is hard, it acts as a surface protection.

The thickness of each layer from the first layer to the third layer of the anti-reflection film of the present invention is 0.16 to 0.34 with respect to the design center wavelength.
Eh, the second layer is 044~0.56, and the third layer is 0.23~
028λ is preferably provided.

[Example: A synthetic resin substrate with a diameter of 15 mm was placed in a chamber with a diameter of 560 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@-5 Torr or less. A diffusion pump or cryopump with a cold trap was used for the exhaust system. Thereafter, without heating the synthetic resin substrate, antireflection films having the film configurations shown in Tables 1 to 5 were deposited by electron beam heating at a deposition rate of 05 to 1.0 nm/sec.

(Leaving space below) Table 1 (Example 1) λ = 500 nm Table 2 (Example 2) λ = 500 nm Table 3 (Example 3) E = 500 nm Table 4 (Example 4) E = 500 nm Table 5 (Example 5) ) = 500 nm The reflectance characteristics of the antireflection films of Examples 1 to 5 are shown in Figures 1 to 5.
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 were evaluated for adhesion to the substrate, moisture resistance, and thermal shock resistance using the following methods.

fl) Adhesion; Width] was evaluated by attaching a 0mm adhesive tape (cellophane adhesive tape) to the anti-reflection film, instantly peeling off one end of the adhesive tape from an angle of 45°, and observing the peeling state of the film. .

(2) Moisture resistance: 300°C in environments with a temperature of 45℃ and 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 a 1O cycle in which the sample was left in an environment 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.

The results of evaluating the adhesion, moisture resistance, and impact resistance of the antireflection films of Examples 1 to 5 are shown in Table 6.

(The following is a blank space) Table 6 As can be seen from the results in Table 6, the reflective coating of the present invention has excellent durability in terms of adhesion, moisture resistance, and thermal shock resistance.

[Effect of the invention 1 As described above, according to the antireflection coating for synthetic resin optical parts of the present invention, LaF a or NdF3 is used as the adhesive layer with the synthetic resin, so it has high adhesion to the synthetic resin. The anti-reflection film is stable and highly productive.

[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. Patent Applicant: Olympus Optical Industry Co., Ltd.

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 lanthanum fluoride or neodymium fluoride, and a mixture of zirconium oxide and titanium oxide or a mixture of zirconium oxide and tantalum oxide. An antireflection coating for a synthetic resin optical component, characterized by comprising a second layer consisting of silicon dioxide and a third layer consisting of silicon dioxide. (2) 1.54≦n_1≦1.58 0.16λ≦n_
1d_1≦0.34λ1.85≦n_2≦2.10 0
．． 44λ<n_2d_2≦0.56λ1.45≦n_3
≦1.47 0.23λ≦n_3d_3≦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; The antireflection coating for a synthetic resin optical component according to claim 1, characterized in that it satisfies the following conditions: film thickness n_3; refractive index of the third layer n_3d_3; optical film thickness λ of the third layer; center wavelength.