JPH05100107A - Reflection mirror - Google Patents

Abstract

PURPOSE:To increase reflectivity and to prevent the degradation in the reflectivity at and under a high temp. and high humidity and the peeling of a metallic layer by providing at least one layer of resin layers contg. the fine powder of a low-refractive index material on the light reflection surface of the metallic layer. CONSTITUTION:The metallic layer 2 is provided on a high-polymer base body 5 and at least one layer of the resin layers 1 contg. the fine powder of the low-refractive index material are provided on the light reflection surface of the metallic layer 2. Further, a high-refractive index layer is provided thereon and an under coat layer may be provided under the metallic layer 2. One or >=2 kinds among magnesium fluoride, silicon oxide, aluminum fluoride, calcium fluoride, lithium fluoride, sodium fluoride, and thorium fluoride are used as the fine powder of the low-refractive index material to be incorporated into the resin layer 1. The resin binder resin of the fine powder is properly selected from resins having film formability; for example, polyester resin, acrylic resin, vinyl resin, polycarbonate resin, polyolefin resin, polyurethane resin, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mirror, and more particularly to a light reflecting mirror having a metal layer provided on a polymer substrate.

[0002]

2. Description of the Related Art A layer of aluminum, silver, chromium or the like is provided as a metal layer for light reflection on a molded body made of a polymer substrate such as an acrylic resin or a polycarbonate resin. It is common practice to form a silicon oxide layer as a protective layer and a reflection enhancing film by vapor deposition. However, when the mirror having such a structure is left in a high temperature environment of 60 [deg.] C. or higher, minute cracks are generated in the silicon oxide layer, resulting in a decrease in reflectance. Furthermore, when left in a high-temperature and high-humidity environment, the metallic layer becomes cloudy and the film peels off around the cracked part, and the performance as a reflecting mirror is greatly deteriorated.

In addition, for example, utility model publication
As shown in FIG. 7, the reflecting mirror described in Japanese Patent No. 0305 has a reflective layer having a three-layer structure including an ultraviolet curable resin layer, a metal reflective layer and an ultraviolet curable top coat layer on a substrate. There is. As described above, when the ultraviolet curable resin is provided as the top coat, the effect of increasing the light reflectance of the metal reflective layer is not sufficient and the performance becomes unsatisfactory.

[0004]

DISCLOSURE OF THE INVENTION In a mirror in which a light reflecting layer made of a metal layer is provided on a polymer substrate, the reflectance is greatly increased as compared with the surface reflection of only the metal layer, and at high temperature and high temperature. An object of the present invention is to obtain a light-reflecting mirror in which the reflectance is not reduced and the metal layer is not peeled off even when installed in a humid environment.

[0005]

In the mirror of the present invention, at least one resin layer containing fine powder of low refractive index material is provided on the light reflecting surface of the metal layer provided on the polymer substrate. Characterize. Further, a high refractive index layer may be further provided in contact with the low refractive index resin layer containing the low refractive index material fine powder on the light reflecting surface. The high refractive index layer may be a resin layer containing fine powder of a high refractive index material, or may be a layer made of an inorganic substance.

Specifically, a low-refractive-index resin layer, a low-refractive-index material fine powder (for example, an average particle size of 0.3 to 200 nm, preferably 0.5 to 100 nm) contained in a resin layer is magnesium fluoride (for example, Refractive index 1.38),
Silicon oxide (eg, refractive index 1.46), aluminum fluoride (eg, refractive index 1.33 to 1.39), calcium fluoride (eg, refractive index 1.44), lithium fluoride (eg, refractive index 1.36 to). 1.37), sodium fluoride (for example, 1.32 to 1.34), and thorium fluoride (for example, 1.45 to 1.5) are used alone or in combination of two or more.

As the fine powder binder resin, a film-forming resin such as polyester resin, acrylic resin, vinyl resin, polycarbonate resin, polyolefin resin, polyurethane resin, melamine resin, epoxy resin, polyamide resin, alkyd resin, It may be appropriately selected from vinyl chloride resin, fluororesin, silicone resin and the like.

An organic solvent capable of dissolving the binder is added to the organic resin binder and the fine powder of low refractive index material to prepare a coating composition, but the kind and the amount of the solvent are not particularly limited. Binder solubility,
The one suitable for the coating method is appropriately selected in consideration of the boiling point and the viscosity. Generally, the amount of solvent will range from 50 to 98% by weight, based on the total composition including the solvent. The antireflection coating composition can be prepared according to a method similar to that of many resin coating materials, and the application of the coating composition to a target article is not particularly limited as long as it can form a thin film thickness. Instead, a normal coating method can be adopted. Dipping, especially in that a thin film and smooth surface can be obtained
Methods such as spin coating and gravure printing are suitable. The coating film is, if necessary, subjected to a curing treatment by an ordinary method such as ultraviolet irradiation curing or heat curing under appropriate conditions depending on the type of the organic resin binder used.

Metal Layer A simple substance of metal such as Al, Cr, Cu, Ag and Au or an alloy material is used with a film thickness of 1000 to 5000Å. As a method for forming the film, a vacuum vapor deposition method, a grasshopper method, or an ion plating method is used.

High Refractive Index Layer -1 High Refractive Index Polymer Layer High Refractive Index Material Fine powder (for example, having an average particle size of 0.3 to 200)
nm, preferably 0.5 to 100 nm), cerium oxide (for example, refractive index 2.2 to 2.5), zinc sulfide (for example, refractive index 2.2 to 2.3), titanium oxide (for example, refractive index 2. 2 to 2.7), zirconium oxide (for example, refractive index 1.95 to 2.0), and aluminum oxide (for example, refractive index 1.59 to 1.62) can be used. One or two or more of these are used, and the fine powder binder resin is selected from those listed as the binder resin for the low refractive index polymer layer, and is adjusted, coated, heat-cured or cured by the same method. UV cured. Coating thickness is λ
₀ as the design wavelength and reflectance maximum, generally assumed to have an optical thickness of lambda _0/2.

-2 High Refractive Index Inorganic Layer As the high refractive index material, one or a mixture of titanium oxide, tantalum oxide, cerium oxide, zirconium oxide, zinc sulfide, and a mixture of titanium oxide and praseodymium is used. by the sputtering method, an optical thickness of λ _0/2
To form a layer of.

Undercoat Layer An undercoat layer composed of a single layer or a plurality of layers made of an inorganic material or a polymer resin is preferably provided between the polymer substrate and the metal layer. -1 As the inorganic material single layer, a film thickness of 100 to 200
A 0Å chromium metal, a titanium metal, or a nitride thereof is provided by a vacuum deposition method or a sputtering method. -As the polymer resin single layer, an ultraviolet curable resin,
For example, TB3003 manufactured by ThreeBond Co., Unidick 17-80p (trademark) manufactured by Dainippon Ink and Koei Hard M-101 (trademark) manufactured by Koei Chemical Industry Co., Ltd. are formed into a coating film thickness of 1 to 5 μm by spinner coating or dipping coating. , UV light is irradiated to cure. -3 After providing the polymer resin layer (-2), the inorganic material layer (-1) may be provided.

Substrate Made of resin material, polymethylmethacrylate, polycarbonate, polystyrene, polyethersulfone,
A resin molding such as polyether ketone or amorphous polyolefin resin is used.

Protective coat Further, a protective coat layer may be provided for protecting the metal layer. When the coating layer is a resin material, an ultraviolet curable resin is used, and Unitic V-9080 manufactured by Dainippon Ink,
The same V-5500 (trademark) is formed with a thickness of 0.5 to 5 μm by spinner coating or dipping coating, and is irradiated with ultraviolet light to be cured. Of course, a thermosetting resin can be used as the undercoat and the protective coat.

[0015]

【Example】

Example 1 As shown in FIG. 1, a vapor deposition film of metal aluminum was formed on a PMMA (polymethylmethacrylate) substrate at a vacuum degree of 2 × 10 ⁻⁵ Torr or less to a thickness of 2000 Å. On the other hand, polyester resin [Dainippon Ink Watersol S-12
3 (trademark)] 0.4 part by weight, average particle diameter 130Å (50 to 2
7 parts by weight of MgF ₂ fine powder having a distribution of 50Å) and a mixed solvent of methyl ethyl ketone / toluene (mixing weight ratio 50: 5)
0) 40 parts by weight were mixed and stirred in a ball mill to obtain a coating composition. This was applied onto the substrate having the above metal layer formed thereon by a dipping method to form a layer 1 having a dry film thickness of 185 mμ. However, the refractive index of the film is 1.35 and the design wavelength is λ500mμ.
And to optical film thickness of the is obtained by the λ _0/2. Wavelength 450n
The light reflectance at m was 87% before coating, but 9 after coating.
It improved to 0%. The spectral reflectance is shown by curve 1 in FIG. In addition, the change in light reflectance after leaving at 60 ° C. and 90% humidity for 1 week was only a decrease of 1%, and the appearance was not clouded or cracked. Further, a commercially available UV curable resin [Unitic V-9080 or V-55 manufactured by Dainippon Ink Co., Ltd. is used as a polymer material for mixing fine MgF ₂ powder.
No. 00 resin (trademark)] was used instead to form a low-refractive polymer layer by irradiation with ultraviolet rays, but almost the same result was obtained.

Example 2 As shown in FIG. 2, a vacuum degree of 3 × 1 was set on a PMMA substrate.
A vapor deposition film of a silver material having a thickness of 2500 Å at 0 ^-5 Torr or less is formed, and a low refractive index polymer layer containing MgF ₂ fine powder is further provided in the same manner as in Example 1, and further as a high refractive index layer,
A vacuum layer kept at an oxygen gas pressure of 2 × 10 ^-4 Torr was deposited by electron gun heating using titanium oxide as a deposition material to obtain an optical film thickness λ _0.
A / 2 mμ titanium oxide (TiO ₂ ) layer was formed. That is, the light reflectance at a wavelength of 450 nm was improved to 92%, which was 4% higher than that of the silver single layer. The spectral reflectance is shown by the curve 2 in FIG. Even after the environment test at 60 ° C. and 90% humidity, no change in the appearance of the surface was observed and the reflectance did not decrease.

Example 3 As shown in FIG. 3, chromium was used as a vapor deposition material on a PMMA substrate, the nitrogen gas pressure was maintained at 1 to 3 × 10 ^-4 Torr, and high frequency ion plating vapor deposition was performed to obtain 200.
A chromium nitride layer of Å ~ 300Å is formed, and the vapor deposition material is aluminum, and the film thickness is about 2 at a vacuum degree of 2 × 10 ^-5 Torr or less.
A 500 Å reflective film was formed, and a low refractive index polymer layer containing MgF ₂ fine powder was formed in the same manner as in Example 1.
The same effects as in Example 1 were obtained for the light reflection preventing effect and the environment resistance performance at 60 ° C. and 90% humidity.

Example 4 As shown in FIG. 4, an ultraviolet curable resin (TB3003 manufactured by ThreeBond Co., Ltd.) as an undercoat layer was formed on a reflecting mirror substrate made of polymethylmethacrylate resin by a spinner to have a cured film thickness of 2 μm. , And aluminum film as metal layer by vacuum evaporation (low resistance heating) to a film thickness of 200
Formed to 0Å. The light reflectance was 88% at a wavelength of 450 nm. Further thereon, a low refractive index polymer layer 185 mμ and a titanium oxide (TiO ₂ ) layer 113 mμ as a high refractive index layer were laminated in the same manner as in Example 2. The light reflectance is improved to 92% at a wavelength of 450 nm, and the aluminum mirror surface does not deteriorate such as cracks or cloudiness even in the environment resistance test at 60 ° C and 90% humidity, and the light reflectance is maintained at 92%. It was

Example 5 As shown in FIG. 5, a low-refractive-index resin layer (film thickness 185 mμ) equivalent to that of Example 1 in which fine powder of magnesium fluoride was mixed into a PMMA substrate was provided, and A was used as a reflective layer.
The material is laminated by a vacuum deposition method in a vacuum degree of 2 × 10 ^-5 Torr or less at 2000 Å, and a UV-curable unitech resin V-5500 (trademark) made by Dainippon Ink Co. A film having a thickness of about 2 μm was formed. Initial characteristics with a light reflectance of 88% (wavelength 450 nm) were obtained, and 60
Even in an environment resistance test in which the metal film was left standing for 1 week at 90 ° C. and 90% humidity, the cloudiness of the metal film did not occur and no decrease in reflectance was observed. In this embodiment, it goes without saying that a high refractive index layer may be provided between the substrate and the low refractive index layer.

In the above embodiment, the thickness of the metal film is 2000 to 3
It was 000Å, and the light reflectance was 80% or more. Even in a semi-transparent reflecting mirror in which the thickness of the metal film is set to several tens to several hundreds of liters, similar improvements in reflectance and environmental resistance can be obtained.

Comparative Example As shown in FIG. 6, a UV curing resin (TB3003 manufactured by ThreeBond) was spinner-coated to a thickness of 2 μm as an undercoat layer on a methylmethacrylate substrate, and an aluminum material was vacuum-deposited as a reflective layer. And thickness 2
Formed to 000Å. Although the light reflectance was 88%,
When left in an environment of 60 ° C. and 90% humidity for 1 week, the surface became cloudy and the reflectance decreased to 70%.

[0022]

When a molded body of polymethylmethacrylate (PMMA) resin is used as the substrate and a low refractive index resin layer is provided on the metal layer as shown in FIGS. 1 to 6,
Further, when a high refractive index layer is laminated, an undercoat layer is provided on these layers, and when only a metal layer is formed as shown in FIG. Table 1 shows the reflectance value and the change in appearance at a wavelength of 450 nm where the change in light reflectance is large when left at 60 ° C. and 90% humidity for 1 week.

[0023]

[Table 1] Initial configuration value Environmental resistance Light reflectance Light after standing for 1 week (wavelength 450 nm) Reflectivity, appearance 1 Example 1 (Fig. 1) Layer MgF ₂ fine powder, layer Al layer 90% 89% 2 Example 2 (FIG. 2) Layer layer Same as Example 1 TiO ₂ coat layer 92% 90% 3 Example 3 (FIG. 3) Layer layer Same as Example 1 Chromium nitride layer 90% 90% 4 Example 4 (FIG. 4) Layer Layer Layer Same as Example 2 UV curable resin 92% 92% 5 Example 5 (FIG. 5) Same as Layer Example 1 Layer Al layer, Layer protective layer 88% 88% 6 Comparative Example ( (Fig. 6) 88% 70% Layer The same white turbidity as in Example 4.

As described above, in the present invention, since the environment resistance is improved by including the fine powder having the low refractive index which causes the increase in the reflectance in the resin layer, it is possible to improve the environment resistance under the high temperature and high humidity environment. In addition, we were able to obtain a reflecting mirror with little performance deterioration.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a reflection mirror of the present invention having only one low refractive index layer on a reflection layer.

FIG. 2 is a configuration diagram of an embodiment of a reflection mirror of the present invention having a high refractive index layer on a low refractive index layer.

FIG. 3 is a structural diagram of an embodiment of a reflection mirror of the present invention having an undercoat layer below a reflection layer and a low refractive index layer above it.

FIG. 4 is a structural diagram of an embodiment of a reflective mirror of the present invention having an undercoat layer below a reflective layer and a low refractive index layer and a high refractive index layer above it.

FIG. 5 is a configuration diagram of a back reflector which is an embodiment of the present invention having a protective coating layer on the back side of a reflecting layer.

FIG. 6 is a configuration diagram of a reflective mirror that is a comparative example having no resin layer on the reflective layer.

FIG. 7 is a configuration diagram showing an example of a conventional reflection mirror.

FIG. 8 is a spectral reflectance curve diagram of Examples 1 and 2.

[Explanation of Codes] Low Refractive Index Resin Layer Metal Layer High Refractive Index Layer Undercoat Layer Substrate Protective Coating UV Curing Resin Layer UV Curing Topcoat Layer

Claims (6)

[Claims] 1. A light-reflecting mirror having a metal layer provided on a polymer substrate, wherein at least one resin layer containing fine powder of low refractive index material is provided on the light-reflecting surface of the metal layer. 2. The light reflecting mirror according to claim 1, further comprising a high refractive index layer provided in contact with the low refractive index resin layer containing the low refractive index material fine powder on the light reflecting surface. 3. The light reflecting mirror according to claim 2, wherein the high refractive index layer is a resin layer containing fine powder of high refractive index material. 4. The light reflecting mirror according to claim 2, wherein the high refractive index layer is a layer made of an inorganic material. 5. The light-incident surface is on the substrate side, and the low refractive index layer or a laminate of the low refractive index layer and the high refractive index layer is provided between the substrate and the metal layer. 2 light reflection mirrors 6. The light reflecting mirror according to claim 5, wherein a protective layer is provided on the back side of the metal layer.