JPH03229202A - Antireflection film for plastic lens - Google Patents

Abstract

PURPOSE:To enhance optical, mechanical and chemical characteristics and to make improvement in the durability of these characteristics by forming the antireflection film of a specific structure. CONSTITUTION:The 1st layer is formed of the composite film of a low refractive index consisting of a metal oxide film which has 0.09 to 0.14lambda optical film thickness and consists of tantalum, zirconium and yttrium and a silicon oxide film which has 0.04 to 0.07lambda optical film thickness. The 2nd layer is formed of a high-refractive index film consisting of a metal oxide film which has 0.24 to 0.28lambda optical film thickness and consists of the tantalum, zirconium and yttrium and the 3rd layer is formed of a low-refractive index consisting of a silicon oxide film which has 0.24 to 0.26lambda optical film thickness. The vapor deposited films obtd. in such a manner are extremely chemically stabler than a ZrO2 film like a Ta2O5 film and have the transparency equiv. to the transparency of the ZrO2 film. The excellent optical, mechanical and chemical characteristics are obtd. in this way and the improvement in the durability of these characteristics is made.

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 particularly to a low refractive index film and a high refractive index film useful for plastic lenses. This invention relates to a multiple anti-reflection film formed by alternately laminating layers.

[Prior Art] Optical elements such as optical lenses, filters, polarizers, and semi-transparent mirrors have traditionally been made mainly 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-reflective coatings are generally formed as vapor-deposited films made from metals or metal oxides, and consist of a single layer of vaporized anti-reflective films, and alternately laminated layers of low refractive index films and high refractive index films. It is broadly divided into multilayer antireflection 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.

Vapor-deposited films made from zirconium oxide (ZrO2) have been widely used as high refractive index films for multilayer anti-reflection films provided on optical elements made of inorganic glass, as they satisfy the above characteristics. As for the high refractive index layer of the multilayer anti-reflection film provided in the optical element, from the viewpoint of excellent transparency and high refractive index, for example, as disclosed in JP-A-56-116003,
A vapor deposited film using ZrO2 as a raw material is used.

[Problems to be Solved by the Invention] However, when a deposited film made from ZrO2 is deposited on a substrate, such as a plastic lens, on which the substrate temperature cannot be sufficiently lowered during film formation, the film does not change over time. There was a problem that the accompanying decrease in heat resistance was not small enough for practical use.However, in recent years, improvements have been made to lens design to improve the optical performance of plastic lenses and reduce lens thickness. Aspheric lens designs with shallower refractive surfaces are now being 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 was a need for an anti-reflection film with low reflection, but since the refractive index of the vapor-deposited film made of ZrO2 mentioned above is 1.90, there is a limit to the refractive index, so a high refractive index is required. This also affected the film formation of the high refractive index layer of the multilayer antireflection film, and for example, it was not possible to obtain a high performance antireflection 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.

[i! Means for Solving the Problem] The present invention has been made to solve the above object, 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 made of silicon oxide, and the second layer has an optical thickness of 0.24λ to 0.24λ.
A high refractive index layer consisting of a metal oxide film having an optical thickness of 28λ and containing tantalum, zirconium, and yttrium, and a third layer having a low refractive index film having an optical thickness of 0.24λ to 0.26λ and consisting of a silicon oxide film. An object of the present invention is to provide a multilayer antireflection film for plastic lenses, characterized by comprising:

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 group containing an organosilicon polymer to be formed on the lens substrate is a layer made of a compound selected from the group consisting of compounds having the following general formula and/or hydrolysates thereof, using a dip method. 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 (R) (R2)bSi(OR3)4-(, +b.

a (Here, R and R are an alkyl group having 1 to 10 carbon atoms, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkenyl group, an epoxy group, a (meth)acryloxy group, a mercapto group, or a cyano It is an organic group having a group and is bonded to a silicon group through a 5i-C bond, R3 is an alkyl group, an alkoxyalkyl group, or an acyl group having 1 to 6 carbon atoms, and a and b are 0
．． 1 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, γ-
Chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyltripropoxysilane, 3,3゜3-trifluoropropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glyside xyprobyltriethoxysilane,
γ-(β-glycidoxyethoxy)propyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3゜4-epoxycyclohexyl)ethyltriethoxysilane, γ-methacryloxypropyl Trimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γmercaptopropyltriethoxysilane, N-β
Trialkoxy or triazyloxysilanes such as (amine ethyl)-T-aminopropyltrimethoxysilane, β-cyanoethyltriethoxysilane, and dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyljethoxysilane, phenylmethyljethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyljethoxysilane, γ-glycidoxypropylphenyldimethoxysilane, γ-glycidoxypropylphenyldiethoxysilane, γ- chloropropylmethyldimethoxysilane,
γ-chloropropylmethyljethoxysilane, dimethyldiacetoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyljethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyljethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyljethoxysilane,
Examples include dialkoxysilanes or diacyloxysilanes such as methylvinyldimethoxysilane and methylvinyljethoxysilane.

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, 5ea-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, carbonic acid, especially alkali metal salts or ammonium salts, furthermore, flukoxides 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 components, obtaker actor (1
A colloidal sol of inorganic oxides such as Si, AI, Ti, Sb, etc., as disclosed in J. 962, p. 251, 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~ 0.6λ 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 (Ta20s) powder, and yttrium oxide (Y2O3) powder, pressing under pressure, and sintering. Preferably, the material is formed into a pellet shape and deposited by electron beam heating. The composition ratio of the mixed raw material obtained by mixing each powder is, in terms of molar ratio, Zr
O2 is 1.0, Ta205 is 0.8-1.8, Y
It is preferable that 2O3 is 0.05 to 0.3.

The vapor deposited film thus obtained (hereinafter referred to as a three-component vapor deposited film) is Ta2051J! Similarly, it is chemically extremely stable compared to ZrO2 film, and has transparency comparable to ZrO2 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.

In addition, 7a20s is 0.8 for 1 mol of ZrO2
When Y203 is less than 1.8 mol or more than 1.8 mol, absorption tends to occur in the resulting 3-component deposited film, and when Y203 exceeds 0.3 mol, the deposition rate becomes faster and the resulting 3-component deposited film is Absorption is likely to occur, and the vapor deposition raw material is also likely to scatter, 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-mercapdobu O bionate, 6 parts by weight of di-n-butyl phosphate, and 0.25 parts by weight of dibutyltin dilaurate. parts by weight and 0.5 parts by weight of 2-(2-hydroxy-5'-1-octylphenyl)benzotriazole as an ultraviolet absorber were mixed, thoroughly stirred, and then aerated for 60 minutes under a vacuum of lmmHg. I did it.

Next, the mixed solution was poured into a mold consisting of a glass lens mold and a resin gasket, and heated from 25°C to 12°C.
The temperature was raised continuously to 0°C over 20 hours, then 120°C.
Polymerization was carried out by holding at ℃ for 2 hours. 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 nd=1, 592, and νd=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 γ-glycidoxypropyltrimethoxysilane while 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 size 1Q nm, fixed content 30%) and 34ffi 1 part Denacol EX-521 (manufactured by Nagase Kasei 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 the mixture was further aged for 100 hours to obtain a coating liquid.

(Formation of hard coat film) The high refractive index polyurethane lens produced by the method described above was
After being immersed in a 10% NaOH aqueous solution at 0°C for 5 minutes and thoroughly washed, coating was performed using the dip method (pulling speed 120 m/min) using the coating solution prepared in the above manner. After curing by heating for 1 hour, the resin was slowly cooled to obtain a hard coated plastic lens.

(Formation of multilayer antireflection film) Next, a sintered body of SiO2 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 ZrO2 powder, Ta20s powder and Y203 powder in a molar ratio of 1:
After mixing at a ratio of 1°3:0.2 and press forming,
Using a pellet-shaped lens sintered at 200°C, place the aforementioned plastic lens in an R-setting tank and heat it for 8 hours while evacuating it.
After heating to 5°C and evacuation to 2 x 10' 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 made of a silicon oxide film as shown in Table 1. , a first layer low refractive index film consisting of a composite equivalent film of a three-component vapor deposited film and a silicon oxide film, 3
A multilayer antireflection film was formed by sequentially forming a second layer of high refractive index film made of a component vapor-deposited film and a third layer of low refractive index film made of silicon oxide. The base layer was used primarily to improve adhesion to the substrate.

Margin below Table - *: The first layer low refractive index film is It is a composite equivalent membrane.

In addition, when evaluating the mechanical properties, chemical properties, and durability of these properties of the multilayer antireflection coating formed in this way and the plastic lens having the multilayer antireflection coating, we also examined the appearance of the lens, the scratch resistance, and , adhesion, heat resistance, alkali resistance, acid resistance and weather resistance were evaluated and measured in the following manner.

・Exterior Visually check the following 1) using a 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 340 type 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.

- The surface of the multilayer antireflection film was rubbed with scratch-resistant steel wool #0OOO, 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.

・1mm1ifiR lens surface with adhesive multilayer anti-reflection coating
After 100 cross-cuts were made, cellophane tape was strongly applied and then rapidly peeled off to examine whether or not the multilayer antireflection film, base layer, and cured film were peeled off.

- Lenses provided with a heat-resistant multilayer anti-reflection film were heated in an oven for 1 hour, and the presence or absence of cracks was examined. The heating temperature started at 70°C and was increased in 5°C increments, and superiority or inferiority was determined based on the temperature at which cracks occur.

- Alkali resistance A lens provided with a multilayer antireflection film was immersed in a 1Qwt% Na0)-1 aqueous solution for 24 hours, and the state of erosion on the surface of the multilayer antireflection film was observed.

- Acid-resistant 10 wt% HC1 aqueous solution and 10 wt% H2SOa aqueous solution were immersed for 3 hours in a lens provided with a multilayer antireflection film, 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 the multilayer antireflection coating obtained good evaluation and measurement results for all items, and had excellent mechanical and chemical properties. It was confirmed that these characteristics were excellent in durability.

Of these evaluations and measurement results, the evaluation and measurement of 8 items of appearance, rough reflectance, scratch resistance, impact resistance, adhesion, heat resistance, alkali resistance, and acid resistance were obtained in this example. 380 plastic lens with multilayer anti-reflection coating
The reflectance on both sides of the lens in the ~780nm wavelength range is
When measured using a Hitachi, Ltd. model 340 self-recording spectrophotometer, the spectral reflectance curve shown in Figure 1 shows that the plastic lens with the multilayer antireflection film obtained in this example had a poor reflection. It was confirmed that it had excellent antireflection properties with a ratio of 1% or less.

[Effects of the Invention] As explained above, the multilayer antireflection coating of the present invention has excellent optical properties, mechanical properties, and chemical properties even when deposited at a relatively low temperature, and these properties are excellent. Excellent durability.

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, the film formation method of the present invention allows for the creation of low antireflection coatings, which are sometimes useful for high refractive index plastic lenses.

[Brief explanation of drawings]

FIG. 1 is a spectral reflectance curve of a plastic lens having a multilayer antireflection film obtained in an example. Fat O 1st Flash 7Q○ Long (IIm)

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~
The composite film has a low refractive index of 0.07λ and a silicon oxide film, and the second layer has an optical thickness of 0.24λ.
~0.28λ and a high refractive index film made of a metal oxide film containing tantalum, zirconium, and yttrium;
A multilayer antireflection film for a plastic lens, characterized in that the third layer is composed of a low refractive index film having an optical thickness of 0.24λ to 0.26λ and consisting of a silicon oxide film.