JPH03144501A - Antireflection film for plastic lens - Google Patents

Abstract

PURPOSE:To improve mechanical characteristics and chemical characteristics and the durability thereof by successively forming an underlying layer of a silicon oxide film, a low-refractive index film of a 1st layer which is the film equiv. to the composite of a vapor deposited three-component film and a silicon oxide film, a high-refractive index film of a 2nd layer which is a vapor deposited three-component film, and a low-refractive index film of a 3rd layer which is a silicon oxide film. CONSTITUTION:This antireflection film includes the low-refractive index composite film which consists of the metal oxide film having 0.09 to 0.14lambda optical film thickness and contg. tantalum, zirconium and yttrium and the silicon oxide film having 0.04 to 0.07lambda optical film thickness in the 1st layer counted from the substrate side. This film is constituted by including the high-refractive index film having 0.47 to 0.7lambda optical film thickness and consisting of the metal oxide film contg. the tantalum, zirconium and yttrium in the 2nd layer and the low-refractive index film having 0.24 to 0.26lambda optical film thickness and consisting of the silicon oxide film in the 3rd layer. The excellent optical characteristics, mechanical characteristics and chemical characteristics are obtd. even when the films are deposited by evaporation at a low temp. and the durabilities of these characteristics are improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an antireflection film that prevents surface reflection of optical elements, and in particular to a low refractive index film and a high refractive index film useful for plastic lenses. This invention relates to a multilayer antireflection film formed by alternately laminating layers.

[Conventional technology]

Traditionally, optical elements such as optical lenses, filters, polarizers, and semi-transparent mirrors have been mainly made of inorganic glass.
In recent years, due to its light weight and excellent impact resistance,
Plastics are becoming more widely used.

In such an optical element, surface reflection not only reduces the transmittance of the optical system but also increases the amount of light that does not contribute to image formation, causing a reduction in image contrast. For this reason, many optical elements, both optical elements made of inorganic glass and optical elements made of plastic, are provided with an antireflection film on their surfaces to reduce surface reflection.

Anti-reflection coatings are generally formed as vapor-deposited films made from metals or metal oxides, and include single-layer anti-reflection films with one layer of vapor-deposited films, and multilayer films with alternating layers of low refractive index films and high refractive index films. It is broadly divided into anti-reflection coatings. Both single-layer anti-reflection coatings and multi-layer anti-reflection coatings have optical properties such as having a desired refractive index, optical homogeneity, and excellent transparency, as well as scratch resistance. It is required to have mechanical properties such as excellent elasticity and adhesion, and chemical properties such as excellent acid resistance and heat resistance.

As a high refractive index film for a multilayer anti-reflection film provided on an optical element made of inorganic glass, a vapor-deposited film made from zirconium oxide (ZrOz) has been widely used as a film that satisfies the above characteristics. Regarding the high refractive index film of the multilayer anti-reflection film provided on the optical element, Z is used, for example, as disclosed in Japanese Patent Application Laid-Open No. 56116003, because of its excellent transparency and high refractive index.
A vapor deposited film using rO□ as a raw material is used.

[Problem to be solved by the invention] However, when deposited films using ZrOz as a raw material are deposited on a substrate, such as a plastic lens, where the substrate temperature cannot be raised sufficiently during film formation, the film may change over time. There has been a problem in that it is difficult to say that the resulting decrease in heat resistance is sufficiently small for practical use.

On the other hand, in recent years, as an improvement from lens design to improve the optical performance of plastic lenses and reduce lens thickness, aspheric lens designs with shallower curves on the refractive surfaces of lenses have been used. . However, in terms of lens design, making the curve of the refractive surface shallow has the problem that, for example, in the case of a spectacle lens, there is a problem of back surface reflection, that is, reflection of incident light from the concave surface side (eye side) is easily received.

Therefore, there has been a need for an antireflection film with low reflection, but the refractive index of the vapor-deposited film made of Zr0z mentioned above is around 1.90, and there is a limit to the refractive index, so it cannot be used in multilayer films that require a high refractive index. This also affected the film design of the high refractive index layer of the anti-reflection film, and for example, it was not possible to obtain a high-performance anti-reflection film that could suppress the reflectance to 1% or less.

Therefore, the first object of the present invention is to solve the above-mentioned problems, to provide excellent optical, mechanical, and chemical properties even when deposited at low temperatures, and to improve the durability of these properties. A second object of the present invention is to provide a multilayer antireflection film with low reflection.

(Means for Solving the Problems) The present invention has been made to solve the above objects, and
In a multilayer antireflection film for plastic lenses formed by alternately laminating a low refractive index film and a high refractive index film, the first layer has an optical thickness of 0.09λ to 0.14λ when counted from the substrate side.
and a metal oxide film containing tantalum, zirconium, and yttrium, and an optical film thickness of 0.04λ to 0.0.
7λ and a low refractive index composite film consisting of a silicon oxide film and the second layer have an optical thickness of 0.47λ to 0.47λ.
7λ and a metal oxide film containing tantalum, zirconium, and yttrium, and the third layer has an optical thickness of 0.24λ to 0.26λ and a low refractive index film made of a silicon oxide film. An object of the present invention is to provide a multilayer antireflection coating for plastic lenses, characterized in that it is composed of a film.

The multilayer anti-reflection coating of the present invention is preferably used for high refractive index plastic lenses with nd=1.54 or higher, particularly n
It is preferably used for high refractive index lenses with d of 1.57 to 1.61.

Further, the lens base material is not particularly limited.

When providing the multilayer antireflection coating of the present invention on a plastic optical element, a hard coat layer containing an organic silicon polymer is formed on the surface of the optical element by a coating method such as a dipping method or a spin code method. Preferably, the multilayer antireflection film of the present invention is provided on the film.

The hard coat film containing the organosilicon polymer to be formed on the lens substrate is formed by dipping a layer consisting of a compound selected from the group consisting of compounds having the following general formula and/or their hydrolysates. It can be obtained by forming it on a polyurethane lens substrate by a coating method or the like and then curing it.

General formula (Rt)a (Rz)b S i (OR3)4
-(i+1+1 (here, R1 and Rt are 1 to 1 carbon atoms)
0 alkyl group, aryl group, halogenated alkyl, halogenated aryl, alkenyl, or epoxy group, (
It is an organic group having a meth)acryloxy group, a mercapto group, or a cyano group and is bonded to silicon through a 5t-C bond, and R8 is an alkyl group, an alkoxyalkyl group, or an acyl group having 1 to 6 carbon atoms. Yes, a and b are 0, ■ or 2, and a+b is 1 or 2. ) Examples of these compounds include methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxyethoxysilane, methyltriacetoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, Vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriacetoxysilane, T-chloropropyltrimethoxysilane, T-chloropropyltriethoxy Silane, γ-chloropropyltripropoxysilane, 3,3゜3-trifluoropropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, T-(β~glycid xyethoxy)propyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3゜4-epoxycyclohexyl)ethyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-a Hinopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γmercaptopropyltriethoxysilane, N
-β(Acarinoethyl)-γ-aminopropyltrimethoxysilane, trialkoxy or triazyloxysilanes such as β-cyanoethyltriethoxysilane, and dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyljethoxysilane, phenylmethyl Jetoxysilane, γ-glycidoxypropylmethyldimethoxysilane, T-glycidoxypropylmethyljethoxysilane, T-glycidoxypropylphenyldimethoxysilane, γ-glycidoxypropylphenyldiethoxy Silane, T-chloropropylmethyldimethoxysilane, γ-chloropropylmethyljethoxysilane, dimethyldiacetoxysilane, γ-methacryloxypropylmethyldimethoxysilane, T-methacryloxypropylmethyljethoxysilane, T-mercaptopropylmethyldimethoxysilane , T-mercaptopropylmethyljethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyljethoxysilane, methylvinyldimethoxysilane, methylvinyljethoxysilane, and other dialkoxysilanes or diacyloxysilanes. .

These organosilicon compounds can be used alone or in combination of two or more.

Furthermore, although not used alone, there are various tetraalkoxysilanes or their hydrolysates that can be used in combination with the above-mentioned organosilicon compounds.

Examples of such tetraalkoxysilanes include methyl silicate, ethyl silicate, n-propyl silicate, isopropyl silicate, n-butyl silicate, 5ec-butyl silicate, and t-butyl silicate.

These organosilicon compounds can be cured even in the absence of a catalyst, but in order to further accelerate curing,
Various catalysts can be used.

Such catalysts include Lewis acids, various acids or bases containing Lewis acid salts, or organic carboxylic acids, chromic acid, hypochlorous acid, boric acid, bromic acid, selenite, thiosulfuric acid, orthosilicic acid, and thiocyaninic acid. Metal salts such as acid, nitrous acid, aluminic acid, and carbonic acid, particularly alkali metal salts or ammonium salts, and also alkoxides of aluminum, zirconium, or titanium, or complex compounds thereof can be used.

Furthermore, it is also possible to use the above-mentioned organosilicon polymer in combination with other organic substances, such as epoxy resins, acrylic copolymers, or hydroxyl group-containing polymers such as polyvinyl alcohol. .

In addition, as other excipient ingredients, Obtikaaku (1
Si, A1. A colloidal sol of inorganic oxides such as , Ti, and Sb can be used.

Furthermore, in order to facilitate the coating operation, it is also possible to use solvents and various additives that maintain good storage conditions.

In addition, in order to improve the adhesion, scratch resistance, etc. between the optical element and the multilayer antireflection film, it is necessary to use a hard coat film and a multilayer reflection film formed between the optical element and the multilayer antireflection film or on the surface of the optical element. It is preferable to interpose a base layer between the protective film and the base layer. For example, a vapor deposited film of silicon oxide or the like can be used, and in that case, the optical film thickness is 0.4λ. ~0.6
λ is preferably used.

In addition, in forming the multilayer antireflection film of the present invention, in addition to the vacuum evaporation method, methods such as a sputtering method using a similar sintered body as a target material and an ion blating method can also be used.

In the present invention, a vapor-deposited film of metal oxides containing tantalum, zirconium, and yttrium is produced by mixing zirconium oxide (ZrO2) powder, tantalum oxide (Ta20.) powder, and yttrium oxide (YzOi) powder, pressing under pressure, and sintering. Preferably, the material is made into a pellet shape by vapor deposition using an electron beam heating method. The composition of the mixed raw material obtained by mixing each powder is such that the molar ratio is ZrO
2 is 1.0, Ta, ○, is 0.8 to 1.8, Y2
It is preferable that O, is 0.05 to 0.3.

The vapor deposited film thus obtained (hereinafter referred to as 31i, vapor deposited film) has a T a of 0. Like the film, it is chemically extremely stable compared to ZrO2 film and has transparency comparable to Zr○22 film. Furthermore, it exhibits a high refractive index of, for example, 2.00 to 2.10, which is effective from the viewpoint of film design.

Note that Ta2O is 0.8 for 1 mol of ZrO2.
If the amount is less than 1.8 mol or more than 1.8 mol, absorption tends to occur in the resulting 3-component vapor deposited film, and Y203 is 0.3
When the amount exceeds the molar amount, the vapor deposition rate increases, and absorption is likely to occur in the resulting three-component vapor deposited film, and scattering of the vapor deposition raw material is likely to occur, making it difficult to control.

〔Example〕

Examples of the present invention will be described below.

(Production of high refractive index polyurethane lens) 100 parts by weight of m-xylylene diisocyanate, 142 parts by weight of pentaerythritol tetrakis-3-mercaptopropionate, 6 parts by weight of di-n-butyl phosphate, and dibutyltin dilaure-l -0.25 parts by weight and 0.5 parts by weight of 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole as an ultraviolet absorber were mixed, stirred thoroughly, and then heated under a vacuum of lmmHg. 60 minutes 3 Deaeration was performed.

Next, the mixed liquid was poured into a mold consisting of a glass mold for Shinzu and a resin gasket, and heated at 25°C for 1 hour.
The temperature was raised continuously to 20'C over 20 hours, and then held at 120C for 2 hours to carry out polymerization. After polymerization, the gasket was removed and the lens mold and lens were separated to obtain a high refractive index polyurethane lens.

The obtained lens had good optical properties of n=1.592 and va=36.

(Preparation of coating liquid) 54 parts by weight of a 0.06N hydrochloric acid aqueous solution was added dropwise to 212 parts by weight of T-glycidoxypropyltrimethoxysilane with stirring. After the dropwise addition was completed, the mixture was stirred for 24 hours to obtain a hydrolyzate.

Next, 424 parts by weight of antimony pentoxide sol (methanol dispersion sol, average particle diameter 10 nm, fixed needle 30%) and 34 parts by weight of Bunacol EX-521 (manufactured by Nagase Kaei Co., Ltd., polyglycerol polyglycidyl ether) as an epoxy compound. After stirring for 5 hours, 6.8 parts by weight of dibutyltin laurate was added as a curing catalyst, and an additional 100 parts by weight was added.
A coating solution was obtained by carefully observing the time.

(Formation of hard coat film) The high refractive index polyurethane lens produced by the method described above was
After immersing in a 10% NaOH aqueous solution at 0°C for 5 minutes and thoroughly washing, coating was performed using the dip method (pulling speed 12 cm/min) using the coating solution prepared in the above manner. After being cured by heating at °C for 1 hour, it was slowly cooled to obtain a hard coated plastic lens.

(Formation of multilayer anti-reflection film) Next, a sintered body of Sing was used as a vapor deposition raw material for the underlayer and low refractive index film to be provided on this hard coated plastic lens, and Zr0z powder, Taxes powder and Y2O, powder in molar ratio i:
1. Mix in a ratio of 20 and 2 parts a, press mold, then 1
Using a pellet made by sintering at 200°C, the aforementioned plastic lens was placed in a vapor deposition tank and heated to 85°C without evacuation.
After evacuation to 2 x 10-5 Torr, the above vapor deposition raw material was vapor-deposited on the surface of the plastic lens using an electron beam heating method to form a base layer consisting of a silicon oxide film and a three-layer vapor-deposited film, as shown in Table 1. A first layer low refractive index film made of a composite equivalent film of and a silicon oxide film, a second layer high refractive index film made of a 3T2 minute vapor deposited film, and a third layer low refractive index film made of silicon oxide. A multilayer antireflection film having a film structure formed by sequential film formation was formed. The main purpose of the base layer is 6. Table 7 Also, the mechanical properties, chemical properties, and durability of these properties of the multilayer antireflection film formed in this way and the plastic lens having this multilayer antireflection film. In evaluating the properties, the appearance, scratch resistance, adhesion, heat resistance, alkali resistance, acid resistance, and weather resistance of the lenses were evaluated and measured in the following manner.

・Visually check the following 1) using an exterior lighting device with a fluorescent lamp as the light source.
It was observed whether conditions 4) to 4) were satisfied.

1) Be transparent.

2) No irregularities on the surface.

3) No striae.

4) There are no foreign objects or scratches on the surface.

・Luminous reflectance 380 ~ using Hitachi's new model 340 self-recording spectrophotometer
The reflectance in the 780 nm wavelength range was measured, and the luminous efficiency was calculated from this reflectance and the luminous efficiency curve.

- Scratch Resistance 8 The surface of the multilayer antireflection film was rubbed with steel wool #0000, and the scratch resistance was visually judged. The judgment criteria were as follows.

A: Even if you rub it hard, there will be almost no scratches.

B: If you rub it too hard, it will get scratched quite a bit.

C: Scratches similar to those on the lens substrate.

・127 in the center of impact-resistant anti-reflective high refractive index plastic lens
A steel ball weighing 16 g was dropped from a height of 1 cm to examine whether the lens was damaged or not.

・The lens surface with the adhesive multilayer anti-reflection coating is coated with 10 strips at 1 mm intervals.
A 0-mesh cross cut was made, a cellophane tape was firmly attached, and then rapidly peeled off to examine whether or not the multilayer antireflection film, base layer, and cured film were peeled off.

- Lenses coated with a heat-resistant multilayer anti-reflection coating were heated in an oven for one hour, and the presence or absence of cracks was examined. Heating temperature starts from 70°C and increases to 5°
The temperature was increased by C increments, and the superiority or inferiority was judged based on the temperature at which cracks occur.

- Alkali resistance A lens provided with a multilayer antireflection film was immersed in a 10wt% NaOH aqueous solution for 24 hours, and the state of erosion on the surface of the multilayer antireflection film was observed.

・Acid resistance 10wt% HCI aqueous solution and 10wt%Hz SO
A lens provided with a multilayer antireflection film was immersed in the aqueous solution for 3 hours, and the state of erosion on the surface of the multilayer antireflection film was observed.

・In order to examine weather resistance and durability, lenses equipped with a multilayer anti-reflection film were exposed outdoors for one month, and after this, the appearance, scratch resistance, adhesion,
Heat resistance, alkali resistance and acid resistance were evaluated and measured as described above.

As a result, the multilayer antireflection coating of this example and the plastic lens having this multilayer antireflection coating obtained good evaluations and measurement results for all items, with good mechanical and chemical properties. In addition to being excellent, these properties were also found to be excellent in durability.

Of these evaluations and measurement results, Table 2 shows the evaluation and measurement results for 8 items: appearance, luminous reflectance, scratch resistance, impact resistance, adhesion, heat resistance, alkali resistance, and acid resistance. Weather resistance, that is, the evaluation results of the above eight items after one month of outdoor exposure are shown in Table 3.

The reflectance of the plastic lens having the multilayer antireflection film obtained in this example on both surfaces of the lens in the wavelength range of 380 to 780 nm was measured using a new model 340 self-recording spectrophotometer manufactured by Hitachi. As shown in Figure 1, whose spectral reflectance curve is shown, the plastic lens with the multilayer antireflection film obtained in this example has excellent antireflection properties with a luminous reflectance of 1% or less. confirmed.

〔Effect of the invention〕

As explained above, the multilayer antireflection coating of the present invention has excellent optical, mechanical, and chemical properties even when deposited at a relatively low temperature, and these properties are also excellent in durability. There is.

Therefore, by implementing the present invention, optical properties, mechanical properties, and chemical properties can be improved even for optical elements, such as plastic optical elements, in which the substrate temperature cannot be raised during the formation of an antireflection film. By providing a multilayer antireflection film that has excellent characteristics and excellent durability, it becomes possible to maintain the optical characteristics of an optical element at a high level over a long period of time.

Furthermore, by forming the film according to the present invention, it is possible to obtain a low antireflection film that is sometimes useful for high refractive index plastic lenses.

[Brief explanation of the drawing]

FIG. 1 is a spectral reflectance curve of a plastic lens having a multilayer antireflection film obtained in an example. 3

Claims (1)

[Claims] (1) In a multilayer anti-reflection film for plastic lenses formed by alternately laminating low refractive index films and high refractive index films, the first layer has an optical thickness of 0.09λ to 0.09λ when counted from the substrate side. ．．
14λ and a metal oxide film containing tantalum, zirconium, and yttrium, and an optical film thickness of 0.04λ~
A composite film with a low refractive index of 0.07λ and a silicon oxide film and a second layer have an optical thickness of 0.47λ.
A high refractive index film consisting of a metal oxide film having an optical thickness of ~0.7λ and containing tantalum, zirconium, and yttrium, and a third layer having an optical thickness of 0.24λ to 0.26λ and consisting of a silicon oxide film. A multilayer antireflection coating for plastic lenses characterized by comprising a low refractive index film.