Optical member having antireflection film

【0001】

[Technical field to which the invention belongs]

The present invention relates to an optical member having an antireflection film on a plastic substrate, and more particularly to an optical member having an antireflection film on a plastic substrate having good heat resistance.

【0002】

[Conventional technology]

Conventionally, an optical member in which an antireflection film is formed on a plastic substrate is well known. As an example, Japanese Patent Application Laid-Open No. 2-291501 discloses an optical member having an antireflection film having a high refractive index layer of λ / 2 containing titanium dioxide as a main component. However, in general, an optical member provided with an antireflection film on a plastic substrate has better heat resistance than an optical member provided with an antireflection film on a glass substrate because it cannot be heated during vapor deposition. Not. Therefore, there has been a demand for an optical member in which an antireflection film is formed on a plastic substrate having further improved heat resistance.

【0003】

[Problems to be Solved by the Invention]

The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical member having an antireflection film on a plastic substrate having good heat resistance.

【0004】

[Means for solving problems]

As a result of diligent efforts to solve the above-mentioned problems, the present inventor has made a novel idea that a layer made of silicon dioxide, which is a low refractive index substance, is used as an equivalent film of three or more layers in a high refractive index layer. It has been found that the heat resistance of the optical member is remarkably improved by the means. Conventionally, the high refractive index layer of λ / 2 has been further configured by using a high refractive index vapor deposition material such as titanium dioxide, zirconium oxide, and tantalum oxide in consideration of antireflection characteristics and production efficiency. Providing a layer made of silicon dioxide, which is a low refractive index substance, in the high refractive index layer has a high possibility of lowering the refractive index of the high refractive index layer and lowering the antireflection property of the antireflection film. No such configuration has been proposed.

【0005】

That is, in the present invention, the plastic substrate and λ / 4-λ / 2-λ / 4 on the plastic substrate from the substrate side.<u style="single">Type (</u>With antireflection film of λ = 500nm)<u style="single">, And a base layer made of metal niobium provided between the plastic substrate and the antireflection film.</u>Λ / 2 is an equivalent film having three or more layers having a refractive index of 1.80 to 2.40, and an even layer of the equivalent film is an optical member having a silicon dioxide layer. is there.<u style="single">Further, in the present invention, a plastic substrate and λ on the plastic substrate from the substrate side</u><u style="single">/4</u><u style="single">-λ</u><u style="single">/2</u><u style="single">-λ</u><u style="single">/4</u><u style="single">Type (λ = 500</u><u style="single">nm) </u><u style="single">On the antireflection film, a cured film formed by curing a coating composition composed of metal oxide colloidal particles and an organosilicon compound provided between the plastic substrate and the antireflection film, and on the cured film. An optical member having a base layer directly applied to the λ.</u><u style="single">/2</u><u style="single">Layer has a refractive index</u><u style="single">1.80</u><u style="single">~</u><u style="single">2.40</u><u style="single">It is an equivalent film of 3 layers or 5 layers, and provides an optical member having an antireflection film in which an even number layer of the equivalent film is a silicon dioxide layer.</u>【0006】

BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, if the high refractive index layer of λ / 2 is made into an equivalent film of three layers, an optical member having good heat resistance and antireflection characteristics can be obtained. Further, in order to obtain good heat resistance and antireflection characteristics, an equivalent film having more than three layers may be used.

【0007】

Further, the odd layer in the equivalent film of λ / 2 is made of titanium oxide, zirconium oxide, tantalum oxide, niobium oxide, etc., which are known as high-refractive-film vapor deposition materials, from the viewpoint of obtaining good heat resistance and reflectance characteristics. A layer containing a vapor-deposited substance is preferable, and a layer composed of at least one kind of vapor-deposited substance selected from TiO2, Ta2 O5 and Nb2 O5 is preferable, and a layer composed of an Nb2 O5 vapor-deposited substance is most preferable. From the viewpoint of production efficiency, it is preferable that all the odd-numbered layers have the same film composition. The combined refractive index of the high refractive index layer of λ / 2 is in the range of 1.80 to 2.40, and in order to obtain good physical properties, the range of 1.85 to 2.25 is particularly preferable, and λ / so as to satisfy this range of refractive index. The film structure of the high refractive index layer of 2 is formed.

【0008】

In the present invention, a silicon dioxide layer is formed in the λ / 4 layer formed on the high refractive index layer of λ / 2. The λ / 4 layer formed under the high refractive index layer of λ / 2 is preferably an equivalent film of two or more layers in order to obtain good antireflection characteristics and heat resistance. The film composition is a two-layer equivalent film composed of a silicon dioxide layer and a layer made of a highly refractive-deposited material such as titanium oxide, zirconium oxide, tantalum oxide and niobium oxide, a silicon dioxide layer, and a layer made of niobium oxide. A two-layer equivalent film is preferable. Further, from the viewpoint of production efficiency, it is preferable to use the same vapor deposition raw material for producing the λ / 4 equivalent film and the vapor deposition raw material for producing the λ / 2 equivalent film.

【0009】

To form this niobium oxide layer, a method of forming this niobium oxide layer by an ion assist method using 100% niobide oxide as a vapor deposition material, powders of niobium oxide, zirconium oxide and yttrium oxide, or powder to which aluminum oxide is further added is used. It is preferable to carry out the method by sintering, generating vapor of a mixed oxide from the obtained sintered body, and precipitating the generated evaporation on the substrate. Further, in the method of precipitating the evaporated material on the substrate, the mixing ratio of the sintered body is 60 to 90% by weight of niobium oxide and zirconium oxide based on the total amount of the vapor deposition composition in order to obtain good film physical properties. Is preferably 5 to 20% by weight, and yttrium oxide is preferably 5 to 35% by weight. Further, when aluminum oxide is added, it is preferable to add 0.3 to 7.5% by weight based on the total of niobium oxide, zirconium oxide and yttrium oxide.

【0010】

In the optical member of the present invention, a base layer is provided between the plastic substrate and the antireflection film.<u style="single">Ori</u>As the material of the base layer, silicon dioxide or metal niobium is preferable, and metal niobium is particularly preferable. The film thickness is preferably 0.1λ to 5λ in the case of the silicon dioxide layer from the viewpoint of film strength and the like, and 0.005 λ to 0.015 λ is preferable in the case of metal niobium from the viewpoint of ensuring the transparency of the film. When the material of the base layer is metal niobium, it has advantages such as excellent adhesion, heat resistance, impact resistance and wear resistance between the plastic substrate and the antireflection film, and a low absorption rate peculiar to metal. The formation of this metal niobium (Nb layer) is preferably carried out by an ion assist method. Argon (Ar) is preferably used as the ionized gas when the ion assist method is carried out from the viewpoint of preventing oxidation during film formation. This makes it possible to stabilize the film quality and control it with an optical film thickness meter.

【0011】

Further, in order to ensure the adhesion between the plastic substrate and the base layer and to make the initial film formation state of the vapor-deposited substance uniform, the ion gun pretreatment may be performed before the base layer is formed. Oxygen, argon, etc. can be used as the ionizing gas in the ion gun pretreatment, and the preferable range of output is an acceleration voltage of 50V to 200V and an acceleration current of 50mA to 150mA.

【0012】

In the optical member of the present invention, an ordinary vacuum vapor deposition method, an ion assist method, or the like can be used as the method for forming the antireflection film. The plastic substrate used for the optical member of the present invention is not particularly limited, and for example, a methyl methacrylate homopolymer, a copolymer of methyl methacrylate and one or more other monomers, a diethylene glycol bisallyl carbonate homopolymer, and a diethylene glycol. Examples thereof include copolymers of bisallyl carbonate and one or more other monomers, sulfur-containing copolymers, halogen-containing copolymers, polycarbonates, polystyrenes, polyvinyl chlorides, unsaturated polyesters, polyethylene terephthalates, and polyurethanes.

【0013】

The optical member of the present invention may have a cured film between the plastic substrate and the base layer. As the cured film, a coating composition composed of metal oxide colloidal particles and an organosilicon compound is generally used. Examples of the metal oxide colloidal particles include tungsten oxide (WO3), zinc oxide (ZnO), silicon oxide (SiO2), aluminum oxide (Al2O3), titanium oxide (TiO2), zirconium oxide (ZrO2), and tin oxide (ZrO2). SnO2), beryllium oxide (BeO), antimony oxide (Sb2 O5), etc. can be mentioned, and can be used alone or in combination of two or more.

【0014】

In the optical member of the present invention, as a preferred embodiment, for example, the structure shown below<u style="single">Naru (</u>c) can be mentioned.

[table 1]<img he="82" id="000002" wi="159" file="2_0003545359.tif" img-format="tif" img-content="drawing" /> 【0017】

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The physical properties of the optical members in Examples 1 to 6 were measured by the test methods shown below. (1) Visible transmittance The visual transmittance Y of the plastic lens was measured using a Hitachi spectrophotometer U-3410 using a plastic lens having antireflection films on both sides as a sample. (2) Visual reflectance The visual reflectance Z of the plastic lens was measured using a Hitachi spectrophotometer U-3410 using a plastic lens having antireflection films on both sides as a sample. (3) Adhesion 100 1 mm × 1 mm squares were made on the surface of the plastic lens with a razor, cellophane tape was attached on the squares, the tape was peeled off at once, and the number of remaining squares was evaluated. In the table, the number of remaining squares / 100 is shown. (4) Abrasion resistant plastic lens surface with steel wool 1kgf / cm²The load was applied, rubbed for 20 strokes, and evaluated according to the surface condition according to the following criteria. UA: Almost no scratches A: Several thin scratches B: Many thin scratches, several thick scratches C: Many thin scratches, many thick scratches D: Almost bald state [0018]

(5) The heat-resistant plastic lens was heated in a dry oven for 1 hour, and the crack generation temperature was measured. The heating temperature was started at 50 ° C, increased by 5 ° C, and the temperature at which cracks were generated was investigated. (6) The alkali-resistant plastic lens was immersed in 10% of NaOH aqueous solution for 1 hour, and evaluated according to the following criteria according to the surface condition. UA: Almost no change A: There are several punctate film baldness B: There are punctate film baldness on the entire surface C: There are punctate baldness on the entire surface, there are several planar baldness D: Almost all surface baldness (7) ) Impact resistance A lens with a central thickness of 2.0 mm and a lens power of 0.00 was manufactured and a drop ball test specified by the FDA was conducted.

【0019】

Examples 1 to 6<u style="single">Fabrication of substrate A and hard coat layer A</u>In a glass container, 90 parts by weight of colloidal silica (Sno-Tex-40, Nissan Chemical), 81.6 parts by weight of methyltrimethoxysilane of organosilicon compound, 176 parts by weight of γ-glycidoxypropyltrimethoxysilane, 2.0N hydrochloric acid 2.0 A solution prepared by adding parts by weight, 20 parts by weight of acetic acid, and 90 parts by weight of water was stirred at room temperature for 8 hours and then left at room temperature for 16 hours to obtain a hydrolyzed solution. To this solution, add 120 parts by weight of isopropyl alcohol, 120 parts by weight of n-butyl alcohol, 16 parts by weight of aluminum acetylacetone, 0.2 parts by weight of a silicone-based surfactant, and 0.1 parts by weight of an ultraviolet absorber, and at room temperature. After stirring for 8 hours, it was aged at room temperature for 24 hours to obtain a coating liquid. A plastic lens substrate pretreated with an alkaline aqueous solution (material: diethylene glycol-rubisallyl carbonate, refractive index 1.50, center thickness 2.0 mm, lens power 0.00, hereinafter may be referred to as "substrate A") is described above. The lens was immersed in the coating liquid, and after the immersion was completed, the plastic lens pulled up at a pulling speed of 20 cm / min was heated at 120 ° C. for 2 hours to form a cured film. After that, the ion gun treatment is performed using Ar gas under the conditions of the ion acceleration voltage and irradiation time shown in Tables 1 to 6, and the hard coat layer (hereinafter referred to as "A layer") is described as a cured film by the ion assist method. May) formed.

【0020】<u style="single">Preparation of base layer and antireflection film</u>Next, a functional film composed of the first to eighth layers shown in Tables 1 to 3 is formed on the hard coat A layer by the ion assist method under the conditions shown in Tables 1 to 3, and a plastic lens is formed. Got The above (1) to (7) were evaluated for the obtained plastic lenses, and the results are shown in Tables 1 to 6. In the table, λ is the wavelength of the irradiation light, and λ = 500 nm. The combined refractive indexes of λ / 4 and λ / 2 in Examples 1 to 6 are shown in Table 8.

【0021】

[Table 4]<img he="212" id="000003" wi="154" file="3_0003545359.tif" img-format="tif" img-content="drawing" /> 【0022】

[Table 5]<img he="212" id="000004" wi="154" file="4_0003545359.tif" img-format="tif" img-content="drawing" /> 【0023】

[Table 6]<img he="212" id="000005" wi="154" file="5_0003545359.tif" img-format="tif" img-content="drawing" /> 【0036】

[Table 11]<img he="26" id="000006" wi="159" file="6_0003545359.tif" img-format="tif" img-content="drawing" /> 【0038】

[Effect of the invention]

As described in detail above, the optical member having the antireflection film of the present invention maintains good visual reflectance, visual transmittance, adhesion, abrasion resistance, alkali resistance and impact resistance. Furthermore, the heat resistance is improved.