JP2005234188A - Optical element having optical inorganic thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element having an optical inorganic thin film which hardly causes cracks or the like in an antireflection film or the like in a high temperature atmosphere such as a parked car in summer. <P>SOLUTION: The optical element has a multilayer antireflection film (optical inorganic thin film) 16 on a plastic substrate 10. At least one layer in the multilayer antireflection film 16 is made of the vapor deposition film of a sintered mixture of a composition containing 33 to 74 mass% titanium oxide (TiO<SB>x</SB>, wherein x ranges from 1.5 to 1.88), 19 to 65 mass% lanthanum oxide (La<SB>2</SB>O<SB>3</SB>) and 2 to 7 mass% titanium (Ti). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an optical element including an optical inorganic thin film such as an antireflection film (reflection reduction film) or a mirror film (reflection increase film). Here, the optical inorganic thin film will be described mainly taking an antireflection film or a mirror film as an example, but in any case where a single-layer or multiple-layer optical inorganic thin film is formed to increase or decrease the reflectance, for example, interference It can also be applied to filters.

  Conventionally, an optical element (an optical base material) in which an optical inorganic thin film such as an antireflection film or a mirror film is formed on a plastic substrate is well known.

For example, in Patent Documents 1 to 4, a plastic substrate (organic glass), silicon dioxide (SiO ₂ ), titanium dioxide (TiO ₂ ), tantalum oxide (Ta ₂ O ₅ ), yttrium oxide (Y ₂ O ₃ ) are disclosed. Various optical elements including an antireflection film (optical inorganic thin film) formed of a high refractive index layer having a basic film thickness of λ / 4 mainly composed of an inorganic material such as alumina (Al ₂ O ₃ ) have been proposed. ing.

  However, an optical element having an antireflection film or the like (optical inorganic thin film) on a plastic substrate, like inorganic glass, has a limited heating temperature during vapor deposition for the formation of the antireflection film, so that the antireflection film has a little heat resistance. I can't expect it.

  That is, if the plastic substrate optical element (plastic lens) provided with the antireflection film or the like as described above is left in a place where the temperature becomes a high temperature atmosphere such as in a vehicle, cracks are likely to occur in the antireflection film or the like. . When cracks occur in the antireflection film, the appearance of the plastic lens is impaired, the light transmittance is reduced, and further, cracks (also referred to as crazing or stress cracks) cause the antireflection film, etc. The thin film (multilayer film) on the plastic substrate is peeled off from either the primer film (primer coat) or the hard film (hard coat) interposed between the antireflection film and the plastic substrate. It was easy.

On the other hand, in the case of optical devices such as projectors and DVD players, cracks occur in the antireflection film due to heat from the outside and heat generated from the inside, and the same problems as described above are likely to occur.
JP-A-2-291501 JP-A-4-328501 JP 2002-328201 A Japanese Patent Laid-Open No. 2003-202407

  In view of the above, an object of the present invention is to provide an optical element provided with an optical inorganic thin film in which cracks or the like hardly occur in an antireflection film or the like under a high temperature atmosphere such as in a summer parked automobile.

  As a result of diligent efforts to solve the above problems, the present invention has led to an optical element comprising an optical inorganic thin film of an antireflection film (reflection reduction film) or a mirror film (reflection increase film) having the following constitution. did.

In an optical element comprising an optical inorganic thin film on an optical substrate,
The optical inorganic thin film is characterized by comprising the sintered mixture containing the following composition as a whole or a main component.

Titanium oxide (TiO _x x = 1.5 to 1.8) 33 to 74% by mass,
Lanthanum oxide (La ₂ O ₃ ) 19-65 mass%
Titanium (Ti) 2-7% by mass
By using the specific sintered mixture as a base, the heat resistance is remarkably improved as will be described later in Test Examples.

In the above-described configuration, the optical inorganic thin film has a repeated multilayer configuration of the specific vapor deposition film and the SiO ₂ film, and Ta ₂ O ₅ , Nb ₂ O ₅ , ZrO ₂ , TiO are disposed inside the final SiO ₂ film. _Even if an oxide vapor deposition film selected from any one or more of ₂ and Al ₂ O ₃ is interposed, the heat resistance is improved. Further, in the above configuration, the optical inorganic thin film has a repeated multilayer structure of the specific vapor deposition film and the SiO ₂ film, and Ta ₂ O ₅ , ZrO ₂ and TiO ₂ are disposed inside the final SiO ₂ film. A composite finish comprising an optical inorganic thin film formed on an optical element, as shown in the examples below, rather than a non-intervening film configuration by interposing one or more oxide vapor deposition films selected from the group of The scratch resistance of the film is improved.

  In the above configuration, the optical inorganic thin film is not necessarily formed, but is usually formed on the hard coat via a hard coat and / or a primer coat on the optical substrate.

  The primer coat is preferably formed of a primer coat composition based on a urethane-based or polyester-based thermoplastic elastomer (TPE). Even in the finished composite film in cooperation with the specific vapor deposition film, an improvement in heat resistance (crack resistance) can be expected.

  In the above structure, it is desirable that the hard coat is formed of a hard coat composition obtained by adding a catalyst and metal oxide fine particles (composite fine particles) to a hydrolyzate of organoalkoxysilane. Further improvement in heat resistance (crack resistance) of the finished composite film can be expected.

  In each of the above configurations, it is desirable to provide a surface protective film, which is a water / oil repellent film, on the optical inorganic thin film. Waterproof and antifouling properties can be imparted.

  The surface protective film may be a general-purpose one (for example, KP-801M manufactured by Shin-Etsu Chemical Co., Ltd.), but is formed of a fluorine organic group-introduced silane compound having a fluorine-modified organic group and a reactive silyl group. It is desirable. Compared with a general-purpose surface protective film, the slipperiness is good and the surface scratch resistance is also improved.

  The thickness of the surface protective film is preferably 0.001 to 0.05 μm.

  One of the methods for forming the surface protective film is to attach a surface protective agent mainly composed of a fluorine-based silane compound to a lump of fibrous conductive material and heat it under a vacuum of 1 to 0.0001 Pa. This is a so-called dry processing method (dry coating method) in which a surface protective film is formed on an optical element that does not have the surface protective film.

  This dry processing method makes it easy to obtain a surface protective film with good adhesion and excellent leveling property (uniformity), and can form a surface protective film continuously using the same vacuum chamber. The efficiency is superior to the wet processing method described later.

  Another one of the methods for forming the surface protective film is that the surface protective agent is applied on an optical element not having the surface protective film, and then predetermined in an atmosphere of humidity (RH) 10 to 90% and temperature 10 to 60 ° C. This is a so-called wet processing method (wet coating method) in which a surface protective film is formed by leaving for a period of time.

  This wet processing method is suitable for forming a surface protective film on a large (large area) substrate or a complicated shape in the atmosphere.

  In addition, it is preferable that the present invention is applied to a plastic substrate (organic glass substrate) that requires heat resistance as an optical substrate because the effect becomes remarkable. However, the present invention provides an inorganic substrate (inorganic glass substrate). It is also applicable to materials.

Detailed description of the configuration

  Hereinafter, the configuration of the present invention will be described in detail.

  Here, an organic glass substrate is usually used as the optical substrate, but an inorganic glass substrate can also be used.

The optical element includes an optical lens such as a spectacle lens and a camera lens, a front glass or a front filter of various displays, and an optical prism.
Examples of the organic glass substrate include polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET: polyester), polyurethane, aliphatic allyl carbonate resin, aromatic allyl carbonate resin, polythiourethane, episulfide resin, norbornene. Resin, polyimide, polyolefin, and the like. More specifically, “CR-39” (aliphatic allyl carbonate resin manufactured by PPG CO., N _D : 1.50), “MR-8” (polythiourethane manufactured by Mitsui Chemicals, n _D : 1 .60), “MR-7” (polythiourethane manufactured by Mitsui Chemicals, Inc., n _D : 1.67), “MR-174” (Episulfide resin manufactured by Mitsui Chemicals, Inc., n _D : 1.74), etc. Can be suitably used.

As the inorganic glass, those having a refractive index (n _D ) of 1.55 or more are easily obtained. Barium crown glass (BaK) 1.54 to 1.60, heavy crown glass (SK)> 1.54, special Heavy crown glass (SSK)> 1.60, light barium flint (BaLF)> 1.55, barium flint (BaF)> 1.56, heavy barium flint (BaSF)> 1.585 and the like are suitable. The numbers after each plastics, inorganic glass abbreviations denote each substrate refractive index of the (glass) (n _D).

  In the case of an organic glass substrate, from the viewpoint of scratch resistance, usually a hard coat film is formed, and further, when the hard coat film (1) is formed, in order to increase impact resistance, the primer layer (2) is interposed between the base material.

  (1) The hard coat (composition) is not particularly limited as long as it can impart scratch resistance and the like to the glass surface, but the following silicone type (i) or acrylic type (ii) can be preferably used.

(i) silicone hard coat;
For example, a catalyst and metal oxide fine particles (including composite fine particles) are added to a hydrolyzate of an organoalkoxysilane, and the viscosity is adjusted so that it can be applied with a diluting solvent. Furthermore, a surfactant, an ultraviolet absorber and the like can be appropriately added to this hard coat solution.

  1) As the organoalkoxysilane, those represented by the following general formula can be used.

R1 _a R2 _b Si (OR3) _{4- (a + b)}
(However, R1 is an alkyl group having 1 to 6 carbon atoms, vinyl group, epoxy group, methacryloxy group, and phenyl group, and R2 is a hydrocarbon group having 1 to 3 carbon atoms, a halogenated hydrocarbon group, an aryl group, R3 represents an alkyl group having 1 to 4 carbon atoms or an alkoxyalkyl group, and a = 0 or 1, b = 0, 1 or 2.

  Specifically, tetramethoxysilane, methyltrimethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, trimethylchlorosilane, glycidoxymethyltrimethoxysilane, α-glycidoxyethyltrimethoxysilane, β -Glycidoxyethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane and the like can be mentioned. These can be used alone or in combination of two or more.

  2) Examples of the catalyst include trimellitic acid, trimellitic anhydride, itaconic acid, pyromellitic acid, pyromellitic anhydride and other organic carboxylic acids, nitrogen-containing organic compounds such as methylimidazole and dicyandiamide, metal alkoxides such as titanium alkoxide and zircoalkoxide, Metal complexes such as acetylacetone aluminum and acetylacetone iron, and alkali metal organic carboxylates such as sodium acetate and potassium acetate can be used.

  3) As metal oxide fine particles, colloidal silica, colloidal titania, colloidal zirconia, colloidal cerium oxide (IV), colloidal tantalum oxide (V), colloidal tin oxide (IV), colloidal antimony oxide having an average particle diameter of 5 to 50 mμ (III), colloidal alumina, colloidal iron oxide (III) and the like can be used, and these can be used in combination of two or more, or as composite fine particles, in addition to single use.

  4) As the diluting solvent, polar solvents such as alcohols, ketones, esters, ethers and cellosolves can be suitably used.

  5) The coating method is selected from known methods such as dipping and spin coating. The curing conditions are 1 to 4 hours at 80 to 140 ° C.

(ii) acrylic hard coat;
For example, a polyfunctional acrylic oligomer having 3 or more acryloyloxy groups in one molecule, a monomer, a monomer having a target function, an oligomer, and a photopolymerization initiator are added as essential components. If necessary, additives such as polymerization inhibitors, leveling agents and ultraviolet absorbers, and modifiers such as thermoplastic resins and metal oxide fine particles can be added.

  1) The polyfunctional acrylic oligomer and monomer are compounds having 3 or more acryloyloxy groups in one molecule, and the following can be exemplified.

Polyol acrylate (polyhydric alcohol or (meth) acrylate of polyether type polyhydric alcohol): Trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetramethacrylate, dipentaerythritol pentaacrylate, etc. Polyester acrylate (Polyester acid (meth) acrylate obtained by reacting polybasic acid, polyhydric alcohol and acrylic acid): For example, polybasic acid such as phthalic acid, isophthalic acid, tetrahydrophthalic acid, etc. Trimethylolpropane, pentaerythritol and the like can be representatively used.

  Urethane acrylate (obtained by reacting tri- or higher-valent polyol component, tri- or higher-valent polyisocyanate or polyol polyisocyanate and three components of hydroxyl group-containing polyfunctional (meth) acrylate): As the polyisocyanate such as methylolpropane, HMDI burette or trimer can be representatively used, and as the hydroxyl group-containing polyfunctional (meth) acrylate, the polyol acrylate such as pentaerythritol triacrylate can be representatively used.

  Epoxy acrylate (obtained by reacting (meth) acrylic acid and hydroxyl group-containing (meth) acrylate to epoxy compound): glycerin triglycidyl ether triacrylate, tris (glycidyl ether ethyl) isocyanurate triacrylate, pentaerythritol tetraglycidyl ether Tetraacrylate, phenol novolac polyglycidyl ether polyacrylate, trimethylolpropane polyglycidyl ether polyacrylate and the like.

Others: Trisacryloyloxyisocyanurate, aminopolyacrylate, hexakismethacryloyloxyethylphosphazene, trisacryloyloxyethyl isocyanurate, etc.
2) As the photopolymerization initiator, those exemplified below can be used.

Acetophenone series: 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 4-t-butyl-trichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, mixed photoinitiators (from allyl ketones) ), 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, allyl ketone-containing photoinitiator, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1, etc. Benzoin series: Benzoin Benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl methyl ketal, etc. Benzophenone series: Benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl -4′-methyldiphenyl sulfide, 3,3′-dimethyl-4-methoxybenzophenone, etc. Thioxanthone series: thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone Son, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, etc. Special group: α-a Siloxime ester, acylphosphine oxide, methylphenylglyoxylate, benzyl-9,10-phenanthrenequinone, camphorquinone, dibenzosuberone, 2-ethylanthraquinone, 4 ', 4 "-diethylisophthalophenone, 3 , 3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, etc. At this time, triethanolamine, methyldiethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler ketone), 4,4'- Photopolymerization initiation assistants such as diethylaminobenzophenone and 2-dimethylaminoethylbenzoic acid can be used in combination.

  As a density | concentration of a polymerization initiator, it is 0.5-10 wt% with respect to curable resin, Preferably it is 1-7 wt%.

  3) As the polymerization inhibitor, those exemplified below can be used.

Hydroquinone, methoquinone, p-benzoquinone, phenothiazine, mono-t-butylhydroquinone, catechol, pt-butylcatechol, benzoquinone, 2,5-di-t-butylhydroquinone, anthraquinone, 2,6-di-t- Butylhydroxytoluene, etc.
4) As the leveling agent, hydrocarbon, silicone and fluorine can be used.

  5) Examples of the ultraviolet absorber include hydroxybenzophenone, salicylate, benzotriazole, and hindered amine.

  6) Examples of the thermoplastic resin include polyurethane elastomers, polybutadiene elastomers, acrylonitrile / butadiene elastomers, and the like.

  7) As the metal oxide fine particles and the diluting solvent, those similar to those exemplified for the silicone system can be used.

  The coating method is the same as in the case of the silicone system.

  The curing condition is 2 to 180 seconds under a high-pressure mercury lamp system or metal halide lamp system ultraviolet light source with a tube wall load of 80 to 160 W / cm.

  (ii) The primer layer is particularly preferably formed using a primer based on a thermoplastic elastomer having excellent impact resistance.

  Specifically, 1) a TPU primer composition in which metal oxide inorganic fine particles are added to a urethane-based thermoplastic elastomer (TPU), and 2) the entire or main component of the coating film-forming polymer is an ester-based thermoplastic elastomer (TPEE). The TPEE primer composition to which the same metal oxide inorganic fine particles as those added are added can be suitably used.

  1) TPU is composed of a soft segment composed of long-chain polyol and polyisocyanate, and a hard segment composed of short-chain polyol and polyisocyanate, and added in the form of an aqueous emulsion (emulsion). Is desirable.

  As the metal oxide fine particles, those used for the hard coat described above can be used.

  2) TPEE is a multi-block copolymer using polyester as a hard segment and polyether or polyester as a soft segment. The mass ratio of the hard segment to the soft segment is usually the former / the latter = about 30/70 to 10/90.

  Further, the same metal oxide inorganic fine particles as those of the urethane primer are used for adjusting the refractive index.

  (3) In this embodiment, a single-layer or multilayer optical inorganic thin film is formed on the hard coat to reduce or increase the reflectance. That is, an antireflection film or a mirror film is formed.

And in this embodiment, in an optical element comprising a single-layer or multilayer optical inorganic thin film that reduces or increases the reflectance on a plastic substrate,
At least one layer in the optical inorganic thin film is substantially composed of a sintered mixture (specific vapor deposition film material) of the following composition.

  The sintered mixture uses a vapor deposition material for producing a high refractive index and high grade layer described in JP-A-2002-226967.

Titanium oxide (TiO _x x = 1.5 to 1.8) 33 to 74% by mass
Lanthanum oxide (La ₂ O ₃ ) 19-65 mass%
Titanium (Ti) 2-7% by mass
Specifically, “a mixture of 37.9% by mass of titanium oxide, 58.9% by mass of lanthanum oxide and 3.2% by mass of titanium was homogeneously mixed, granulated to a particle size of about 1 to 4 mm, The mixture was baked at 1500 ° C. for 6 hours (the same as “Example 1”) or “a mixture of 34% by mass of titanium oxide, 63% by mass of lanthanum oxide, and 3.0% by mass of titanium, and a particle size of about 1 to 4 mm. Can be suitably used, such as those obtained by granulating to about 1500 ° C. for 6 hours under reduced pressure (“Example 2”).

  More specifically, those marketed under the product names “Substance H4” and “Substance H5” by Merck Co., Ltd. can be mentioned.

  In addition, the substrate temperature in the vapor deposition of Example 1 and 2 of the said gazette is 280-310 degreeC, and the plastic substrate is not assumed.

  And a vapor deposition layer ("specific vapor deposition film") made of the specific vapor deposition film material and one or more of ceramics or metals other than the specific vapor deposition film material, such as the metal oxide / metal halide, or A general-purpose optical inorganic thin film composed of the combined general-purpose optical inorganic thin film materials is combined to form an antireflection film (reflection reduction film) or a mirror film (reflection mirror: reflection increase film).

  In designing the antireflection film, the optical film thickness is usually selected as an integral multiple of λ / 4 (for example, λ: 500 nm), the required refractive index is calculated from the non-reflective conditions, and the material having the refractive index is calculated. (See Kose et al. “Optical Engineering Handbook” Asakura Shoten, 1996.2, p170).

  The mirror film is designed to be a transparent high refractive index, low refractive index λ / 4 repeating multilayer film (see p. 171).

Here, as an optical inorganic thin film material other than the specific vapor deposition film material (vapor deposition material for producing a high refractive index optical layer),
Any one of titanium, tantalum, zirconium, niobium, antimony, yttrium, indium, tin, lanthanum, cerium, magnesium, aluminum, silicon, etc., or an inorganic oxide comprising two or more types as a component,
Inorganic halides such as magnesium, lanthanum, aluminum and lithium;
Silicon, germanium, chromium, aluminum, gold, silver, copper, nickel, platinum, etc. or a metal mixture (including sintered bodies and alloys) containing two or more of these as components.
And so on.

  The antireflection film and the mirror film are usually formed using a dry plating method (PVD method) such as a vacuum deposition method (including an ion assist method), a sputtering method, an ion plating method, an arc discharge method, or the like.

Then, one layer or a plurality of layers of the antireflection film or mirror film may be deposited (film formation) by performing ion assist. When forming a specific vapor deposition film on organic glass, it is put in a vacuum vessel heated to less than 120 ° C., and a gas containing at least O ₂ is introduced in a timely manner from 5.0 × 10 ⁻¹ to 5.0 × 10 5. It is preferable to perform film formation while performing heating while adjusting the pressure to ⁻³ Pa and further performing ion assist using an ion gun.

  When forming a specific vapor deposition film on organic glass, as heating temperature in a vacuum vessel, it is normal temperature-120 degreeC, Preferably, it is desirable to set it as 50-90 degreeC. Under normal temperature, the density of the formed film is low and sufficient film durability cannot be obtained. When the temperature exceeds 120 ° C., the substrate on which the film is formed may be deteriorated or deformed.

  As ion assist conditions, a gas introduction amount of 1 to 100 sccm (preferably 5 to 50 sccm) and an acceleration voltage of 100 to 1200 V (preferably 200 to 1000 V) are usually set. Here, “sccm” is an abbreviation of “standard cc / m”, and represents one at 0 ° C. and 101.3 kPa (1 atm).

The gas introduced into the ion gun is preferably O ₂ , Ar, or a mixed gas thereof.

  Prior to the ion assist, it is desirable to perform surface treatment of the hard coat film. Specifically, (1) plasma treatment in an oxygen or argon atmosphere, (2) chemical treatment with acid / alkali, (3) ion irradiation treatment (ion cleaning) with oxygen or argon gas with an ion gun, etc. it can. Of these, ion cleaning is desirable.

  Note that ion cleaning and ion assist are described in detail in JP-A-10-123301, JP-A-11-174205, and the like.

  1) Ion cleaning:

  When forming the optical inorganic thin film, it is desirable to perform a surface treatment of the hard coat film as a pretreatment in order to increase the adhesion of the optical inorganic thin film. Specific examples include plasma treatment with high frequency oxygen or argon, chemical treatment with acid or alkali, oxygen ion or argon ion irradiation treatment with an ion gun, and the like.

Of the above, it is desirable to obtain a good surface by irradiating oxygen ions or argon ions with an ion gun. (See JP 10-123301 A, etc.)
2) Ion assist method:
The deposition of at least the high refractive index layer is performed using the ion beam assist method, and the ion beam assist method may be used for other films, or other physical deposition methods may be used. Also good. (See JP-A-11-174205 etc.)
The other constituent layers of the antireflection film or mirror film other than the specific vapor deposition film may be the same ion assist as that of the specific vapor deposition film or other vacuum vapor deposition such as an electron beam. Usually, it is desirable to use an electron beam because the same vacuum chamber can be used.

The refractive index (n) of each vapor deposition material is shown below.
Specific vapor deposition film: 2.0-2.2
SiO ₂ : 1.43 to 1.47
TiO _2: 2.2~2.4
ZrO ₂ : 1.90 to 2.1
Ta ₂ O ₅ : 2.0 to 2.3
Tables 1 and 2 show design examples (layer configuration and film thickness) of the optical inorganic thin film.

そして、本実施形態では、光学無機薄膜の上に、防汚性などの見地から、表面保護膜を形成することが望ましい。

In the present embodiment, it is desirable to form a surface protective film on the optical inorganic thin film from the viewpoint of antifouling property.

  As the surface protective film, a general-purpose one (for example, KP-801M manufactured by Shin-Etsu Chemical Co., Ltd.) can be used, but a fluorine organic group-introduced silane compound having a fluorine-modified organic group and a reactive silyl group is used as a film component ( It is desirable to form it with a coating agent which is a main agent) and has a water contact angle of 80 ° C. or more.

  This fluorinated organic group-introduced silane compound has good antifouling properties and scratch resistance.

  The film thickness of the surface protective film (water / oil repellent film) is usually 0.001 to 0.05 μm, preferably 0.001 to 0.03 μm, and more preferably 0.001 to 0.02 μm. When the thickness of the surface protective film is less than 0.001 μm, water / oil repellency cannot be expected, and there is a problem in scratch resistance and chemical resistance. On the other hand, if it exceeds 0.05 μm, the transmittance tends to decrease due to surface light scattering of the surface protective film.

  Specifically, as a surface protective agent (coating agent) containing a fluorine organic group-introduced silane compound as a film component, a fluorine organic group-introduced silane compound “KY-130 (3)” manufactured by Shin-Etsu Chemical Co., Ltd. is used as a fluorine-based solvent. (For example, HFE-7200 manufactured by Sumitomo 3M, FR thinner manufactured by Shin-Etsu Chemical Co., Ltd.) diluted to an appropriate concentration can be used.

  The method for forming the surface protective film may be the following dry processing method (a) or wet processing method (b).

(a) Dry processing method (dry coating method)
By attaching a coating agent (surface protective agent) in which a fluorine organic group-introduced silane compound is appropriately diluted in a fluorine-based solvent to a lump of fibrous conductive material and heating it under a vacuum of 1 to 0.0001 Pa A surface protective film is formed on the optical element (see, for example, JP-A-6-340966).

  Here, the vacuum pressure during film formation is 1 to 0.0001 Pa, preferably 0.5 to 0.005 Pa, more preferably 0.1 to 0.001 Pa. When the vacuum pressure is higher than 1 Pa, the average free path of the evaporated molecules is short and an appropriate film forming speed cannot be obtained. When the vacuum pressure is lower than 0.0001 Pa, the film forming speed can be obtained, but it takes time to obtain the vacuum state.

  The film formation rate is 0.05 to 5.0 Å / s, preferably 0.1 to 2.0 Å / s. If it is 0.05 kg / s or less, the productivity is poor and the film forming cost is high, and if it is 2.0 kg / s or more, it is difficult to obtain an appropriate film thickness distribution. The film formation rate can be adjusted by adjusting the vacuum pressure / heating temperature.

(b) Wet processing method (wet coating method)
After the same surface protecting agent is applied on the optical element, it is allowed to stand in an atmosphere of humidity (RH) 10 to 90% (preferably 20 to 80%) and temperature 10 to 60 ° C. (20 to 50 ° C.) for a predetermined time. To form a surface protective film. The predetermined time is usually 0.5 to 24 h (desirably 1 to 10 h) although it varies depending on the reaction rate of the surface protective agent and the atmospheric conditions.

  The coating method is arbitrary, such as a dipping method, a spin coating method, a brush coating method, or a spray method.

  In the above, if the atmospheric humidity is too low, it is difficult to obtain sufficient reactivity of the reactive group (by hydrolysis), and conversely if it is too high, poor appearance tends to occur.

  On the other hand, if the ambient temperature is too low, the reaction of the silane compound is slow, whereas if it is too high, appearance defects such as cracks and deformation of the optical element substrate tend to occur in the optical inorganic thin film.

  For example, there is the following method described in the product catalog of “fluorine coating agent KY-8 (3)” (Shin-Etsu Chemical Co., Ltd.).

  "Dilute to an appropriate concentration with a fluorine-based solvent (preferred solvent HFE-7200 (manufactured by Sumitomo 3M), FR thinner (manufactured by Shin-Etsu Chemical Co., Ltd.)), and apply to the surface of the substrate by dipping, brushing, etc. After leaving it to cure under the following conditions, wipe the surface with a dry cloth.

・ Room temperature, humidity 40% ・ ・ ・ 24h or more
・ 60 ℃, humidity 80% ・ ・ ・ 2h or more (recommended condition) ”

  Hereinafter, Examples and Comparative Examples performed for confirming the effects of the present invention will be described in detail. FIG. 1 is a model cross-sectional view showing the basic optical configuration of the example / comparative example.

  (1) The drug and the optical substrate are as follows.

<Drug>
TPEE "Pesresin A-160P" (manufactured by Takamatsu Yushi Co., Ltd., polyester-polyether type water-dispersed emulsion (aqueous), solid content concentration 27%)
-Titania-based metal oxide fine particles A "Optlake 1130F-2 (A-8)" (manufactured by Catalyst Kasei Kogyo Co., Ltd., solid content concentration 30%, dispersion solvent methyl alcohol)
-Titania-based metal oxide fine particle B "Optlake 1120Z (S-7, G)" (manufactured by Catalyst Kasei Kogyo Co., Ltd., solid content concentration 20%, dispersion solvent methyl alcohol)
<Optical inorganic thin film material>
Lanthanum titanate “Substance H4” (hereinafter referred to as “specific vapor deposition film material”)
<Optical substrate (lens body)>
Refractive index 1.60: “MR-8” (Mitsui Chemicals)
Refractive index 1.67: “MR-7” (Mitsui Chemicals, Inc.)
Refractive index 1.74: “MR-174” (Mitsui Chemicals, Inc.)
Each substrate was pre-treated by being immersed in a 10% aqueous sodium hydroxide solution at 40 ° C. for 3 minutes, then washed with water and dried.

  (2) Each primer composition was prepared as follows.

<Primer composition 1>
To 100 parts of commercially available TPEE “Pesresin A-160P”, 57 parts of titania-based metal oxide fine particles “Optlake 1120Z (S-7.G)”, 350 parts of methyl alcohol as a diluent, and silicone-based surfactant “L- A primer composition was prepared by mixing 1 part of 7001 "and stirring until uniform.

<Primer composition 2>
It was prepared in the same manner as Primer Coat 1 except that the titania-based metal oxide fine particles “Optlake 1120Z (S-7, G)” were changed to 210 parts.

  The primer composition and the hard coat composition were applied by a dipping method (pickup speed: 105 mm / min).

  (3) Each hard coat composition is prepared as follows.

<Hard coat composition 1>
To 150 parts of γ-glycidoxypropyltrimethoxysilane and 25 parts of tetraethoxysilane, 150 parts of methyl alcohol is added, and 40 parts of 0.01N hydrochloric acid is added dropwise with stirring to perform hydrolysis all day and night. Prepared.

  The hydrolyzate was mixed with 170 parts of titania-based metal oxide fine particles “Optlake 1130F-2 (A-8)”, 1 part of a silicone surfactant (L-7001) and 1.0 part of acetylacetone aluminum as a catalyst. The mixture was stirred for a whole day and night to prepare a hard coat composition.

<Hard coat composition 2>
It was prepared in the same manner as hard coat 2 except that the titania-based metal oxide fine particles “OPTRAIK 1130F-2 (A-8)” were changed to 350 parts.

  (4) Each optical inorganic thin film (antireflection film / mirror film) is formed as follows.

While the vacuum chamber is heated to 60 ° C., the pressure is evacuated to 1.33 × 10 ⁻³ Pa or less, and after oxygen ion cleaning, ions are sequentially applied from the substrate side so as to have the layer configuration shown in Tables 3 and 4. While performing the assist, vacuum deposition is performed to form an antireflection film or a mirror film.

The ion cleaning acceleration voltage was 200 V, and the ion assist acceleration voltage was 600 V.
(5) Each surface protective film is formed as follows.

  1) Chemical preparation

  Fluorine-based coating agent (KY-130 (3) manufactured by Shin-Etsu Chemical Co., Ltd.) was diluted with a fluorine-based solvent (FR thinner manufactured by Shin-Etsu Chemical Co., Ltd.) to obtain a solid content of 3%. Made by Nippon Steel Wool Co., Ltd., # 0, wire diameter 0.025mm) Filled into a container filled with cylindrical copper (capacity: inner diameter 16mm x inner height 6mm) open upward (chemical filling amount 1.0g And then dried at 120 ° C. for 1 hour.

  2) Film formation

  The above container filled with chemicals is set in a vacuum evaporator, and after making a vacuum of 0.01 Pa, it is evaporated at a film formation rate of 0.6 Å / s with a molybdenum resistance heating boat as a heating source to form a 0.005 μm surface protective film Formed on the surface of each treated element.

  (6) The optical elements (lenses) of each example / comparative example were prepared as follows.

  A primer coat composition is applied to each of the indicated lens base materials, and after curing at 100 ° C. for 20 minutes, a hard coat composition is applied and cured under conditions of 110 ° C. × 2 h. Formed.

  The lens coated with the primer coat / hard coat 12 or 14 is set on a rotating lens dome, and the antireflection film 16 having the design shown in Tables 3 and 4 is formed under the above-mentioned conditions. The surface protective film 18 was formed by the above.

  (7) About each Example / comparative example manufactured as mentioned above, the physical property / evaluation test of each following item was done.

<Test items>
1) Heat resistance test About each optical element (lens test piece) 10 days after the finish composite film formation, the heat resistance was judged as follows using "Perfect Oven" (manufactured by Tabay Espec).

  The test piece was heated at 50 ° C. to 10 ° C. for 5 minutes at each test temperature, and the presence or absence of cracks in the finished composite film was visually observed to determine the test temperature at which cracks occurred.

2) Adhesion test 100 squares were formed in 1 cm square at 1 mm intervals on the test piece, and after strongly pressing the cellophane adhesive tape, it was peeled off rapidly in the 90 ° direction, and the number of squares not peeled was counted.

3) Warm water resistance test The test piece was immersed in 80 ° C. hot water for 10 minutes, and the adhesion test (described above) was performed.

4) Scratch resistance test A load of 1000 g was applied to steel wool (# 0000), and the surface of the finished composite film (antireflection film) of each test piece was rubbed 50 times / 50 seconds to determine the degree of scratches by fluorescent light. It was determined by visual inspection using reflected light and transmitted light. The evaluation criteria are as follows.

5: Almost no scratch
4: Slightly scratched
3: There are some scratches
2: There are scratches
1: There are many scratches
5) Chemical resistance test Acid resistance: After immersing the test piece in a 20 ° C. nitric acid aqueous solution (PH1) for 6 hours, washing it with water, and using a contact angle meter (CA-D type manufactured by Kyowa Interface Science Co., Ltd.), contact angle with pure water Was measured.

  Alkali resistance: The test piece was immersed in an aqueous solution of sodium hydroxide (PH11) at 20 ° C. for 6 hours, washed with water, and then contact angle was measured (described above). The evaluation criteria are as follows.

○: Contact angle of 100 ° or more
Δ: Contact angle 80 ° or more and less than 100 °
×: Contact angle less than 80 °
6) Weather resistance test Accelerated weather resistance test: A carbon arc type sunshine super long life weather meter (manufactured by Suga Test Instruments Co., Ltd.) was exposed for 100 hours to evaluate scratch resistance and adhesion (described above).

<Confirmation of effect>
The test results are shown in Tables 5, 6 and 7.

  Examples 1-12 provided with the anti-reflective film containing the specific vapor deposition film which consists of the specific vapor deposition film material of this invention are excellent in heat resistance compared with the comparative examples 1 and 2 which do not have a specific vapor deposition film. I understand.

Also, among the examples, in particular, when the specific vapor deposition film-SiO ₂ is not repeated, Ta ₂ O ₅ , ZrO ₂ , TiO ₂ is interposed in front of the final SiO ₂ layer, as compared to the case where it is not, It can be seen that the scratch resistance is also improved (Examples 2, 5 and 7 to 10).

Model sectional view of an optical element to which the present invention is applied

Explanation of symbols

10 Optical substrate (lens body)
12 Primer coat 14 Hard coat 16 Optical inorganic thin film (antireflection film or mirror film)
18 Surface protective film

Claims (15)

In an optical element comprising a single-layer or multi-layer optical inorganic thin film in order to reduce or increase the reflectance on a plastic substrate,
An optical element characterized in that at least one layer of the optical inorganic thin film is composed of a vapor deposition film (hereinafter referred to as “specific vapor deposition film”) of a sintered mixture of the following composition.
Titanium oxide (TiO _x x = 1.5 to 1.8) 33 to 74% by mass,
Lanthanum oxide (La ₂ O ₃ ) 19-65 mass%
Titanium (Ti) 2-7% by mass The film structure of the optical inorganic thin film is a repeated multilayer structure of the specific vapor deposition film and the SiO ₂ film, and Ta ₂ O ₅ , Nb ₂ O ₅ , ZrO ₂ , TiO _2, and the like are disposed inside the final SiO ₂ film. The optical element according to claim 1, wherein an oxide vapor deposition film selected from at least one of Al ₂ O _{3 and the} like is interposed. The film configuration of the optical inorganic thin film is a repeated multilayer configuration of the specific vapor deposition film and the SiO 2 film, and the inner layer of the final SiO 2 film includes at least one of the group of Ta ₂ O ₅ , ZrO ₂ , and TiO _2. 2. The optical element according to claim 1, wherein a selected oxide deposition film is interposed.   The optical element according to claim 1, 2 or 3, wherein the optical inorganic thin film is formed on the hard coat via a hard coat and / or a primer coat on the optical substrate.   5. The optical element according to claim 4, wherein the primer coat is formed of a primer coat composition based on a urethane-based or polyester-based thermoplastic elastomer.   5. The optical element according to claim 4, wherein the hard coat is formed of a hard coat composition obtained by adding a catalyst and metal oxide fine particles (composite fine particles) to a hydrolyzate of organoalkoxysilane.   The optical element according to claim 1, wherein a surface protective film (water / oil repellent film) is formed on the optical inorganic thin film.   8. The optical element according to claim 7, wherein the surface protective film is formed of a fluorinated organic group-introduced silane compound having a silyl group reactive with a fluorine-modified organic group.   9. The optical element according to claim 8, wherein the surface protective film has a thickness of 0.001 to 0.05 [mu] m. An optical element having no surface protective film by attaching a surface protective agent mainly composed of the fluorinated organic group-introduced silane compound to a lump of fibrous conductive material and heating it in a vacuum of 1 to 0.0001 Pa. 10. The optical element according to claim 8, wherein the surface protective film is formed on the surface of the optical element.   A surface protective agent mainly composed of the fluorinated organic group-introduced silane compound is applied on an optical element having no surface protective film, and then left for a predetermined time in an atmosphere of humidity (RH) 10 to 90% and temperature 10 to 60 ° C The optical element according to claim 8, wherein the surface protective film is formed. In an optical element comprising a single or multilayer optical inorganic thin film that reduces or increases reflectivity on an optical substrate,
An optical element, wherein at least one layer of the optical inorganic thin film is a specific vapor deposition film made of the sintered mixture composed entirely or mainly of the following composition.
Titanium oxide (TiO _x x = 1.5 to 1.8) 33 to 74% by mass,
Lanthanum oxide (La ₂ O ₃ ) 19-65 mass%
Titanium (Ti) 2-7% by mass   The optical element according to any one of claims 1 to 12, wherein the specific vapor deposition film is formed on a plastic substrate by low-temperature vacuum vapor deposition (25 to 120 ° C).   The optical element according to claim 1, wherein the specific vapor deposition film is formed on a plastic substrate by ion-assisted vacuum vapor deposition. The optical element according to claim 14, wherein the ion-assisted vacuum deposition conditions are a heating temperature of 25 to 120 ° C., an ion gun gas introduction amount of 1 to 100 sccm, and an ion gun acceleration voltage of 100 to 1200 V.

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