JPH09113703A - Synthetic resin lens with antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic resin lens having excellent strength and antireflection performance. SOLUTION: This lens is constituted by laminating, successively from a base material side, a first layer consisting of a low-refractive index material having a refractive index of 1.43 to 1.47 and having an optical film thickness of 0.40 to 0.60λ, a second layer consisting of a high-refractive index material having a refractive index of 1.90 to 2.05 and having an optical film thickness of 0.15 to 0.30λ, a third layer consisting of a high-refractive index material having a refractive index of 2.10 to 2.50 and having an optical film thickness of 0.20 to 0.40λ and a fourth layer consisting of a low-refractive index material having a refractive index of 1.43 to 1.47 and having an optical film thickness of 0.20 to 0.30λ, as antireflection films on the lens base material consisting of a synthetic resin having a refractive index of 1.58 to 1.70.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antireflection film for synthetic resin lenses such as spectacle lenses and camera lenses.

[0002]

2. Description of the Related Art In order to prevent flickering and ghost due to reflection on a lens surface, it is required to reduce surface reflection as much as possible by a method such as attaching an antireflection film to the surface.

Conventionally, in order to obtain an effective antireflection effect in the visible light region, the optical film thickness is λ / 4, λ / 2, λ / 4 or λ / 4, λ / at the wavelength λ which is the center of design. 4,
A film structure of λ / 4 is often used. As the material forming the film, a material having an appropriate refractive index must be selected so that the antireflection effect is sufficiently obtained. As a design that can obtain a low reflectance in a particularly wide wavelength region, the outermost layer disclosed in US Pat. No. 3,185,020 is a low refractive index material having a thickness of λ / 4, and the second inner layer has a λ / There is an antireflection film composed of a high-refractive-index material having a thickness of 2 and a layer of an intermediate-refractive-index material having a thickness of λ / 4 or an equivalent film equivalent to the same, on the inside. In practice, there are often no suitable intermediate refractive index materials, and as shown in U.S. Pat. Nos. 3,565,509 and 3,432,225, a layer of intermediate refractive index material may have a low refractive index material and a high refractive index material. In many cases, it is replaced with an equivalent film of two or three layers in which the refractive index material is alternately laminated to form an antireflection film composed of four to five layers as a whole.

As a method of forming such a film, the vacuum vapor deposition method is generally well used. When the substrate is a synthetic resin, the substrate temperature during film formation must be low (120 ° C. or lower) in order to avoid deformation of the substrate. Therefore, SiO ₂ , TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , and Al ₂ can be used as vapor deposition substances that can obtain sufficient strength even when they are formed at low temperature.
O _{3 and the} like are used alone or as a mixture.

In recent years, a lens made of synthetic resin, n = 1.50, which has been conventionally used in order to reduce the thickness and weight, has been used.
In addition to materials having a moderate refractive index, materials having a high refractive index of n = 1.60 or more have come to be used.

[0006]

When an antireflection film is formed on such a synthetic resin lens, a layer having a high refractive index of λ /
It is difficult to stably produce a film having a thickness of 2 because, in a vacuum deposition method or the like which is usually performed, non-uniformity of the refractive index in the thickness direction easily occurs when vapor deposition is performed at a low temperature. further,
If the layer of the intermediate refractive index material having a thickness of λ / 4 in contact with the substrate is an equivalent film equivalent to that, it is necessary to precisely control the film thickness and the refractive index of the thin layer forming the equivalent film. , It is very difficult to create with good reproducibility. Therefore, there is a problem in that the reflection characteristics such as average reflectance, luminous reflectance, and interference color vary.

[0007]

In order to solve such a problem, the synthetic resin lens with an antireflection film of the present invention is provided on a lens substrate made of synthetic resin having a refractive index of 1.58 to 1.70. In order from the base material side, the optical film thickness of the low refractive index substance having a refractive index of 1.43 to 1.47 is 0.40λ to 0.6.
The first layer of 0λ.

A second layer having an optical film thickness of 0.15λ to 0.30λ and made of a high refractive index material having a refractive index of 1.90 to 2.10.

A third layer made of a high refractive index material having a refractive index of 2.15 to 2.50 and having an optical film thickness of 0.20λ to 0.40λ.

A fourth layer having a low refractive index of 1.43 to 1.47 and having an optical film thickness of 0.20λ to 0.30λ.

It is characterized in that the layers are laminated. λ is a wavelength at the center of design, and is selected from the range of about 480 to 550 nm in order to obtain the antireflection effect in the visible light region. The film thickness of the first layer is about 0.5λ and 2
The layer is set centering on 0.25λ, and the film thicknesses of the second layer and the third layer are adjusted so as to obtain an optimum antireflection effect in accordance with the refractive index of each layer and the substrate.

As the low-refractive index material, SiO ₂ is used as a material that has excellent adhesion to the substrate and can obtain sufficient strength even when a film is formed at a low temperature.

The high refractive index material of the second layer is not particularly limited, but can be widely selected from materials having a refractive index of 1.90 to 2.10, for example, TiO ₂ , Zr.
O ₂ , Ta ₂ O ₅ , Al ₂ O ₃ , CeO ₂ , HfO ₂ , L
Substances such as a ₂ O ₃ , Nd ₂ O ₃ and Pr oxide may be used alone or in combination of two or more.

The high refractive index material of the third layer preferably has a refractive index of 2.15 or higher in order to obtain a sufficient antireflection effect. TiO ₂ or TiO ₂ is 20
A substance whose content is at least wt% and whose balance is ZrO ₂ or Ta ₂ O ₅ or an oxide of a rare earth element such as La or Y is used.

For TiO ₂ , vacuum vapor deposition is carried out with the composition as it is, or TiO _{2 which} is easy to evaporate with little degassing,
Ti ₂ O ₃ , Ti ₃ O ₅ , and Ti ₄ O ₇ alone or in a mixture of a plurality of them are reactively vapor-deposited while introducing oxygen gas so as to become TiO ₂ on the substrate.

In order to obtain a sufficient strength and refractive index even if the film is formed at a lower temperature, an ion beam which is simultaneously irradiated with an oxygen ion beam accelerated by an ion gun provided in the chamber when at least the third layer is deposited. It is effective to perform assisted vapor deposition.

Various synthetic resins can be selected as the lens substrate, but when the refractive index of the substrate becomes 1.58 or less,
Since it approaches the refractive index of SiO _{2 which is} a low refractive index material,
With the configuration of the present invention, a good antireflection effect cannot be obtained.
Even when the refractive index of the substrate is 1.70 or more, it becomes difficult to obtain a good antireflection effect.

In order to improve the scratch resistance of the synthetic resin, the antireflection film of the present invention is laminated on a substrate coated with a hard coating in which fine particles of an inorganic material are dispersed in an organic material containing silicon. You can also do things.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

Example 1 A lens made of a sulfur-containing urethane resin having a refractive index of 1.66 is set in a vacuum chamber and the degree of vacuum is 8 × 10 ⁻⁶ T.
Evacuate to orr. After that, acceleration voltage 500V,
Irradiation with an oxygen ion beam having an ion current density of 20 μA / cm ² was performed for ion cleaning treatment for 60 seconds.
After the treatment, an antireflection film was formed with the following film configuration.

With the wavelength λ at the center of design as 510 nm, the first layer SiO ₂ (refractive index 1.46) is provided with an optical film thickness of 0.50λ and the second layer ZrO ₂ (refractive index 2.00) is provided from the substrate side. Optical film thickness 0.17λ Third layer TiO ₂ (refractive index 2.30) was laminated such that optical film thickness 0.37λ Fourth layer SiO ₂ (refractive index 1.46) was formed to an optical film thickness 0.25λ. . The third layer of TiO ₂ was prepared by ion beam assisted vapor deposition in which Ti ₃ O ₅ was evaporated by electron beam heating and, at the same time, an oxygen ion beam accelerated by an ion gun provided inside the chamber was simultaneously irradiated.

The spectral reflectance characteristics of the antireflection film of this example are shown in FIG. An excellent antireflection performance exhibiting a blue-violet interference color with a luminous reflectance on one side of 0.2% or less was obtained. This antireflection film was also excellent in adhesion to the substrate, weather resistance, moisture resistance, chemical resistance, and scratch resistance.

Example 2 An antireflection film was formed in the same manner as in Example 1 except that a lens made of a sulfur-containing urethane resin having a refractive index of 1.60 had the following film structure.

With the wavelength λ at the center of design as 510 nm, the first layer SiO ₂ (refractive index 1.46) is provided with an optical film thickness of 0.50λ and the second layer ZrO ₂ (refractive index 2.00) is provided from the substrate side. Optical film thickness 0.21λ Third layer TiO ₂ (refractive index 2.30) was laminated so that optical film thickness 0.32λ Fourth layer SiO ₂ (refractive index 1.46) was laminated to an optical film thickness 0.25λ. .

The spectral reflectance characteristics of the antireflection film of this example are shown in FIG. An excellent antireflection performance was obtained in which the luminous reflectance on one surface was 0.2% or less and a reddish purple interference color was exhibited.

(Embodiment 3) A lens made of a sulfur-containing urethane resin having a refractive index of 1.66 is set in a vacuum chamber and evacuated until the degree of vacuum reaches 8 × 10 ^-6 Torr. Then 4x1
Ar gas was introduced so as to be 0 ⁻⁴ Torr and output 40
RF plasma treatment was performed at 0 W for 60 seconds. After the treatment, an antireflection film was formed with the following film configuration.

With the wavelength λ at the center of design as 520 nm, the first layer SiO ₂ (refractive index 1.46) is provided with an optical film thickness of 0.50λ and the second layer ZrO ₂ (refractive index 2.00) is provided from the substrate side. Optical thickness 0.24λ Third layer ZrO ₂ +30 wt% TiO ₂ (refractive index 2.2) is optical thickness 0.25λ Fourth layer SiO ₂ (refractive index 1.46) is optical thickness 0.25λ So that it was laminated.

The spectral reflectance characteristics of the antireflection film of this embodiment are shown in FIG. An excellent antireflection performance exhibiting a blue-violet interference color with a luminous reflectance on one side of 0.2% or less was obtained.

(Example 4) An antireflection film was formed in the same manner as in Example 1 except that a lens made of a sulfur-containing urethane resin having a refractive index of 1.66 had the following film structure.

With the wavelength λ at the center of the design as 510 nm, the first layer SiO ₂ (refractive index 1.46) has an optical film thickness of 0.50λ from the substrate side. The second layer Ta ₂ O ₅ (refractive index 1.95). ) Is an optical film thickness of 0.17λ Third layer TiO ₂ (refractive index 2.30) is an optical film thickness of 0.38λ Fourth layer SiO ₂ (refractive index of 1.46) is an optical film thickness of 0.25λ Laminated.

The spectral reflectance characteristics of the antireflection film of this example are shown in FIG. An excellent antireflection performance exhibiting a blue-violet interference color with a luminous reflectance on one side of 0.2% or less was obtained.

Comparative Example 1 A lens made of a sulfur-containing urethane resin having a refractive index of 1.66 is set in a vacuum chamber and evacuated until the degree of vacuum reaches 8 × 10 ⁻⁶ Torr. Then 4x1
Ar gas was introduced so as to be 0 ⁻⁴ Torr and output 40
RF plasma treatment was performed at 0 W for 60 seconds. After the treatment, an antireflection film was formed with the following film configuration.

With the wavelength λ at the center of design as 520 nm, the first layer SiO ₂ (refractive index 1.46) is provided with an optical film thickness of 0.08λ and the second layer ZrO ₂ (refractive index 2.00) is provided from the substrate side. Optical thickness 0.16λ Third layer SiO ₂ (refractive index 1.46) is optical thickness 0.05λ Fourth layer ZrO ₂ (refractive index 2.00) is optical thickness 0.25λ Fifth layer SiO ₂ ( A layer having a refractive index of 1.46) was laminated so as to have an optical film thickness of 0.26λ.

FIG. 5 shows the spectral reflectance characteristics of the antireflection film of this comparative example. The luminous reflectance on one side was about 0.5%, which was higher than that of the examples according to the present invention, and was a green interference color.

Comparative Example 2 A lens made of a sulfur-containing urethane resin having a refractive index of 1.66 was treated in the same manner as in Example 1 and then an antireflection film was formed with the following film structure.

With the wavelength λ at the center of design as 520 nm, the first layer SiO ₂ (refractive index 1.46) is provided with an optical film thickness of 0.09λ and the second layer TiO ₂ (refractive index 2.30) is provided from the substrate side. Optical thickness 0.08λ Third layer SiO ₂ (refractive index 1.46) Optical thickness 0.09λ Fourth layer TiO ₂ (refractive index 2.30) Optical thickness 0.51λ Fifth layer SiO ₂ ( A layer having a refractive index of 1.46) was laminated so as to have an optical film thickness of 0.25λ.

The spectral reflectance characteristics of the antireflection film of this comparative example are shown in FIG. An excellent antireflection performance was obtained in which the luminous reflectance on one surface was 0.2% or less and a reddish purple interference color was exhibited. However, since it is difficult to accurately form the thin first, second, and third layers, it is not possible to repeatedly obtain the same interference color and antireflection performance.

[0037]

According to the present invention, it becomes possible to easily apply an antireflection film having excellent strength to a synthetic resin lens by vacuum vapor deposition at a low temperature. Furthermore, the film thickness of each layer constituting the antireflection film is within a range that is easy to prepare, and since there is no layer that is too thin, excellent antireflection performance can be obtained with good reproducibility.

Further, this antireflection film has good adhesion to the substrate,
It has excellent weather resistance, moisture resistance, chemical resistance, and abrasion resistance, and is suitable for applications such as spectacle lenses and camera lenses.

[Brief description of the drawings]

FIG. 1 is a diagram showing a spectral reflectance characteristic of Example 1 of the present invention.

FIG. 2 is a diagram showing a spectral reflectance characteristic of Example 2 of the present invention.

FIG. 3 is a diagram showing a spectral reflectance characteristic of Example 3 of the present invention.

FIG. 4 is a diagram showing a spectral reflectance characteristic of Example 4 of the present invention.

FIG. 5 is a diagram showing a spectral reflectance characteristic of Comparative Example 1 of the present invention.

FIG. 6 is a diagram showing a spectral reflectance characteristic of Comparative Example 2 of the present invention.

Claims (4)

[Claims] 1. A lens base material made of a synthetic resin having a refractive index of 1.58 to 1.70, and a low refractive index substance having a refractive index of 1.43 to 1.47 in order from the base material side. The first layer having an optical film thickness of 0.40λ to 0.60λ (λ is a wavelength that is the center of design). The optical film thickness of the high refractive index substance having a refractive index of 1.90 to 2.10 is 0.15λ to 0.
30λ second layer. An optical film thickness of 0.20λ to 0.40λ made of a high refractive index substance having a refractive index of 2.15 to 2.50
Third layer of. A fourth optical film having a refractive index of 1.43 to 1.47 and a low refractive index substance having an optical film thickness of 0.20λ to 0.30λ.
layer. A synthetic resin lens with an antireflection film, which is characterized by being laminated. 2. The synthetic resin lens with an antireflection film according to claim 1, wherein the low refractive index substance is SiO ₂ . 3. The high refractive index material of the third layer comprises TiO ₂ or TiO ₂ in an amount of 20 wt% or more, and the balance is ZrO ₂ or Ta ₂ O ₅ or an oxide of a rare earth element. Item 1. A synthetic resin lens with an antireflection film according to item 1. 4. The synthetic resin lens with an antireflection film according to claim 1, wherein the high refractive index material of the third layer is formed by oxygen ion beam assisted vapor deposition.