JPH0226855B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a light-transmitting sheet that transmits visible light and reflects infrared rays. More specifically, the present invention relates to a selectively transparent sheet that transmits visible light and reflects near-infrared light to infrared light.

[Prior art] In general, in a laminate in which conductive metal thin films such as gold, silver, copper, and various alloys containing these as main components are sandwiched between transparent high refractive index dielectric layers, the thickness of each constituent thin film is controlled. It is known that it is possible to obtain a device that selectively reflects light in a specific wavelength range.

In particular, the laminate, which is transparent in the visible region and selectively reflects infrared wavelengths, can be used as a heat-reflecting film for buildings,
It is effective from the point of view of energy saving in houses, use of solar energy, etc. However, in order to further improve usage efficiency in the field of energy saving in buildings, houses, etc. and solar energy utilization, it is necessary to
It is more effective to impart selectivity to the transmission characteristics in the near-infrared region (701 nm to 2100 nm).
In other words, it is important to further reduce the transmission characteristics of the near-infrared rays, which are invisible to the human eye in the solar energy distribution but are present in about 50% of the heat rays, and further improve the transmission characteristics of the visible rays. It is effective and does not impair transparency in any way, so it can be applied to various fields without affecting the surrounding environment or safety. Examples of application fields include improving the heat insulation of monitoring windows during high-temperature work, further improving the cooling effect by improving the shielding properties of solar energy that enters through the windows of buildings, cars, trains, and other vehicles, and heat shielding of transparent food containers. Examples include further improvements in the cold retention effect in frozen and refrigerated cases. Fabry-Perot filters are generally well known as such optical interference filters having selective transmission properties. This is known as an interference filter that sandwiches a transparent dielectric material having a specific optical thickness between opposing semi-transparent mirrors and transmits only light of a specific wavelength. The US patent states that by applying this Fabry-Perot filter, it is possible to obtain a selective light transmitting sheet with high transmission characteristics in the visible region and high reflection characteristics in the near-infrared region.
It is shown in the specification of No. 3682528. According to it,
For example, the structure of the substrate/metal layer/dielectric/metal layer/dielectric layer is glass/Ni/Ag/Al ₂ O ₃ /Ni/
It has a composition of Ag/Al ₂ O ₃ with a transmittance of 70% or more from 400 nm to 700 nm and a reflectance of about 10%.
A selective light transmitting laminate having a transmittance of 10% or less in the range from 700 nm to 2500 nm and a reflectance of about 90% or more has been obtained.

[Problems] In Fabry-Perot filters, if the thickness of the metal film that is the semi-transparent reflector is made thinner, the transmission wavelength width will be expanded and the transmittance will be improved, and the refractive index of the dielectric material can be lowered. It is known that the transmission wavelength width becomes narrower. If the refractive index and thickness of the dielectric are selected by calculation to obtain a transmission peak at, for example, 550 nm, and the metal film thickness is made sufficiently thin, a filter with high transmission characteristics in the visible region and good blocking characteristics in the near-infrared region will be constructed. I can do that. Conventionally, filters have been mainly used for precision optical applications, and from this point of view, metal compounds such as oxides with stable optical constants and low absorption have been used as transparent dielectrics. However, when used in building windows for energy saving purposes such as blocking solar energy, it is essential to apply it to large areas.
Production on an industrial scale is impossible using conventional metal compounds as transparent dielectrics.

This means that the technology for uniformly covering a large area of the surface of a metal thin film layer with metal oxide or the like is still an incomplete technology. If the metal oxide film is thin and has a thickness of 50 Å or less, it is possible to simply form a metal oxide film from the metal film by thermal oxidation, etc.;
It can be said that it is impossible to uniformly produce an oxide film with a thickness of about 100 mL over a large area on an industrial scale.

[Structure and operation of the invention] We have made extensive studies to apply this structure to a wide range of energy-saving applications such as the use of solar energy.

As a result, we discovered that by uniformly coating an organic compound with a refractive index of 1.35 to 1.65, it is possible to form a transparent dielectric layer that is optically transparent and has uniform porous properties. Ta.

By the way, organic compounds have traditionally not been used in optical materials, with some exceptions, due to their non-uniform optical properties, large optical loss, and lack of long-term stability, which has led to problems with reliability. There was a problem. As a result of further research to overcome the drawbacks of such organic compounds, the present inventors found that such drawbacks could be overcome by using a specific organic compound, ie, an organic crosslinked polymer, in the transparent dielectric layer.The present invention is based on the present invention. has been reached.

That is, the present invention provides a metal thin film layer (B) with a thickness of 40 Å to 300 Å, a transparent dielectric layer (C) with a thickness of 200 Å to 3000 Å, and a transparent protective layer (D) on at least one side of the organic polymer (A). ) is (A)/(B)/(C)/(B) or (A)/(B)/(C)
/
This is a light-transmitting sheet formed by laminating layers (B) and (D) in the order of (B) and (D), in which the transparent dielectric layer (C) is made of an organic crosslinked polymer.

The organic polymer film (A) referred to in the present invention does not need to be particularly limited; It is necessary to have a transparency of 50% or more, preferably 75% or more, and any conventionally known organic polymer film (A) that satisfies this condition may be used.
Among them, polyethylene terephthalate film,
Preferred are polycarbonate film, polypropylene film, polyethylene film, polyethylene naphthalate film, polysulfone film, polyether sulfone film, nylon film, etc., and polyethylene terephthalate film is particularly preferred.

Furthermore, the organic polymers used in the present invention can be used even if colorants, ultraviolet absorbers, pigments, etc. are included in these organic polymer films to the extent that they do not impair the mechanical properties and optical properties of the organic polymer films. There is nothing wrong with this as a film.

The material for the metal thin film layer (B) used in the present invention may be any metal or alloy with low absorption loss in the visible light region and high electrical conductivity.
Among these, it is particularly preferable to use silver as the main component. As for other metals that can be contained, gold, copper, aluminum, etc. are preferable, but any other metal may be contained as long as the content does not deteriorate the properties of silver. The content of silver is an important factor governing the optical properties of the resulting light-transmitting sheet, and it is preferably contained at least 40% by weight, preferably 50% by weight or more.

In addition, in order to obtain a laminate with particularly high infrared reflectivity, a metal thin film layer (B) of an alloy consisting of two or three metals selected from the three elements of gold, silver, and copper, or a single layer of these metals may be used. Preferably, it is a metal thin film layer (B).

The thickness of the metal thin film layer (B) is not particularly limited as long as it satisfies the required optical properties of the obtained light-transmissive sheet, but it may have infrared reflective ability or electrical conductivity. For this purpose, it is necessary to have continuity as a film in at least a certain area. The thickness at which the metal thin film changes from an island-like structure to a continuous structure is preferably about 30 Å or more, and preferably 300 Å or less in order to improve visible light transmission characteristics, which is the object of the present invention.

In order for the light-transmitting sheet to have sufficient visible light transmittance and sufficient infrared light reflectance, it is particularly preferable that the thickness of the metal thin film (B) is about 40 Å or more and about 120 Å or less.

The metal thin film layer (B) can be formed by any conventionally known method, such as vacuum evaporation, cathode sputtering, ion plating, etc. In order to form a stable film, film forming methods using high energy particles such as cathode sputtering and ion plating are preferred. In particular, when obtaining an alloy thin film, the cathode sputtering method is preferred from the viewpoint of uniformity of the alloy composition of the formed thin film and uniformity of the thickness of the formed thin film.

Further, when forming the metal thin film layer (B), the material that will become the substrate plate can be pretreated by a known method in order to stabilize the thin metal layer. These methods include, for example, cleaning treatments such as ion bombardment, undercoating treatments such as coating with organic silicate, organic titanate, organic zirconate compounds, and/or coating of metals such as Ni, Ti, Si, Bi, Zr, V,
There is a nucleation stabilization treatment in which Ta and oxides of these metals are preformed by sputtering, etc., and these should be selected and used appropriately within the range that does not adversely affect the optical properties of the light-transmitting sheet. Good.
If these pre-treatments involve an increase in thickness, the thickness is preferably 100 Å or less. A treatment similar to this pre-treatment may be performed on the metal layer as a post-treatment.

As the organic compound used in the transparent dielectric layer (C) of the present invention, an organic crosslinked polymer is preferably used.

Examples of organic crosslinked polymers include phenolic resin compounds, alkyd resin compounds, unsaturated polyester resin compounds, epoxy resin compounds, polyurethane resin compounds, and other polymers with crosslinkable functional groups that are treated with air, heat, light, or a crosslinking agent. All organic crosslinked polymers which have been crosslinked are preferably used. These crosslinked polymers may be used alone or in combination of two or more.

Such an organic crosslinked polymer is used to form the transparent dielectric layer (C) in the present invention. Since such a transparent dielectric layer (C) is formed by a coating method in the present invention, a polymer having a crosslinkable functional group as described above is mixed with a crosslinking agent if necessary in an appropriate solvent at an appropriate concentration. A method preferably used is to dilute, dissolve, and apply, and then dry or, if necessary, heat-treat, light irradiate, etc., to form an organic crosslinked polymer.

When forming the transparent dielectric layer (C) by such a coating method, if the area is small, it can be obtained by spin coating, coating with a bar coater, doctor knife, etc., and drying.

In the case of a large area, a transparent dielectric layer (C) of any thickness can be formed by drying after coating with a machine such as a gravure roll coater or a reverse roll coater.

In order for the light-transmitting sheet of the present invention to optically achieve its purpose, the thickness of the transparent dielectric layer (C) must be
Must be between 200 Å and 3000 Å. In particular, to increase the transmittance of visible light, from 500Å
Preferably it is between 1500 Å.

In particular, in order for the light-transmissive sheet of the present invention to have maximum transmittance in the vicinity of 550 nm of visible light, it is particularly preferable that the thickness of the transparent dielectric layer (C) is between 600 Å and 1300 Å.

Furthermore, the degree of organic crosslinking used in the transparent dielectric layer (C) of the present invention does not necessarily have to be high, but may be adjusted as appropriate depending on the conditions (environmental conditions, post-treatment conditions, etc.) under which the light-transmitting sheet of the present invention is used. It is preferable to choose.

When using an organic compound for optical purposes like the light-transmitting sheet of the present invention, the physical properties of the resulting coating film control the optical properties of the laminate, so it is necessary to select a resin with excellent purity and uniformity. Along with that,
As for the coating method, it is necessary to appropriately select a method that can achieve a uniform film thickness. Preferably, it is necessary to keep the film thickness within ±5% of the set film thickness.

The light-transmitting sheet of the present invention includes a protective layer (D) on the outermost layer (B) for the purpose of protecting the laminated structure (A)/(B)/(C)/(B) having optical functions. can be formed. Such a protective layer (D) has the role of protecting the laminate of the present invention from mechanical damage, contaminants such as chemicals, intrusion of moisture, etc.

In order to achieve this objective and not adversely affect the optical properties of the laminate, the material for the protective layer (D) is preferably a material that is optically transparent and has excellent protective ability. Materials for the protective layer (D) that can be used in the present invention include inorganic compounds such as oxides of Si, Al, Ti, Zr, Ta, etc., or mixed oxides of two or three of the above metals; Or acrylic resins such as acrylonitrile, polymethacrylonitrile, polymethylmethacrylate, acrylate resins and their copolymers, polystyrene resins,
Films made of organic compounds formed from resins such as vinyl acetate resin, phenoxy resin, polyester resin, polyurethane resin, mixtures thereof, copolymers, crosslinked polymers, etc. are preferably used.

If the usage environment is particularly severe, polyethylene films, polypropylene films, nylon films, triacetate films, polyester films, polyvinyl butyral sheets, polycarbonate sheets, etc. having various thicknesses may be used as a laminate protective layer (D) by a known method. You can also use it.

When using a film made of an inorganic compound as the protective layer (D), physical forming methods such as sputtering, vacuum evaporation, and ion plating are preferably used. A protective layer (D) made of a metal oxide can also be obtained by the metal oxide thin film formation method described above.

When using a film made of an organic compound as the protective layer (D), the protective layer (D) made of the organic compound can be obtained by dissolving it in a suitable solvent that dissolves the resin mentioned above, applying and drying it. Can be done. The protective layer (D) in the present invention is not only a single layer, but also two layers,
It may be a three-layer laminated structure. This may be a mutually laminated structure of an inorganic compound and an organic compound, a mutually laminated structure of organic compounds, or a laminated structure of inorganic compounds. By forming the protective layer (D) with such a laminated structure, it is possible to obtain the protective layer (D) of the present invention having a better protective function.

The thickness of the protective layer (D) of the present invention is not limited as long as it has the ability to protect the laminate, but it is 0.05μ or more in terms of the protective ability, and 50μ in order not to deteriorate the optical properties of the laminate. Below, particularly preferably 35μ
m or less is preferably used.

The light-transmitting sheet of the present invention can be used depending on its purpose. For example, when used for building windows, etc., it can be attached directly to the glass of the window with an adhesive or the like, or it can be attached to double-glazed glass. When used in the windows of automobiles, etc., it can be inserted into laminated glass, known as safety glass, using polyvinyl butyral using a known method. . When the light-transmitting sheet of the present invention is used for such safety glass, it particularly exhibits its properties and can avoid discoloration, cracks, etc.

In this way, the light-transmitting sheet of the present invention can be used in an appropriate manner depending on the purpose of use, and can be effectively used not only in controlling the incidence of solar energy but also in all fields of heat radiation prevention. Can be done.

Hereinafter, the present invention will be specifically explained using Examples. Note that all parts are by weight.

Example 1 A biaxially stretched polyester film with a thickness of 125 μm is used as the substrate (A), and a first layer with a thickness of 80 μm is placed on it as the first layer.
A metal thin film layer (B) consisting of a silver copper thin film layer (containing 10% by weight of copper) with a thickness of 750 Å and a second layer of polymethacrylonitrile (80 parts) and 2-hydroxyethyl methacrylate (20 parts) with a thickness of 750 Å. A transparent dielectric layer (C) consisting of a crosslinked copolymer of is used as the third layer, a silver-copper thin film layer (containing 10% by weight of copper) with the same thickness of 80 Å as the first layer.
Metal thin film layers (B) consisting of (A)/(B)/
A light-transmitting sheet having the configuration (C)/(B) was formed as follows.

The silver-copper thin film layer of the metal thin film layer (B) targets a silver-copper alloy containing 10% by weight of copper and is heated at an Ar gas pressure of 5%.
It was formed by DC magnetron sputtering under ×10 ⁻³ Torr, and the input power was 2 W/cm ² per unit area of the target.

The transparent dielectric layer (C) is made of 1 part of a copolymer of polymethacrylonitrile and 2-hydroxymethacrylate and an isocyanate compound (trade name: Takenate A-
10: Takeda Pharmaceutical Co., Ltd.) 0.5 parts and a copolymer of polymethacrylonitrile and 2-hydroxyethyl methacrylate to a concentration of 2% by weight in a mixed solvent consisting of 5 parts of cyclohexanone, 2 parts of acetone, and 1 part of methyl ethyl ketone. After dissolving the solution, it was coated using a bar coater and dried at 130°C for 3 minutes.

The transmittance of the obtained light-transmissive sheet at a wavelength of 500 nm was 78%, and the infrared reflectance at 10 μm was 82.
It was %.

300 μm thick on both sides of the resulting light-transmissive sheet
After combining 3mm thick polyvinyl butyral sheets and 3mm thick float glass on both sides, 1
A selectively transmitting laminated glass was prepared by holding the glass at 150° C. for 1 hour while applying a pressure of Kg/cm ² . The integrated visible transmittance of the obtained selectively transmitting laminated glass is
71%, and the integrated near-infrared light transmittance was 29%.

Example 2 Example except that the second transparent dielectric layer (C) of Example 1 was replaced with a crosslinked copolymer of polymethacrylonitrile and 2-hydroxyethyl methacrylate and a crosslinked polymer made of polyvinyl alcohol. A light-transmitting sheet having the same structure as Example 1 was formed.

The transparent dielectric layer (C) is made of a cross-linked polymer made of polyvinyl alcohol.
A mixture consisting of 1 part of polyvinyl alcohol (75%) and 0.5 part of formaldehyde was dissolved in water to give 1.4% by weight of polyvinyl alcohol, coated with a bar coater, and dried at 135°C for 2 minutes.

The integrated visible transmittance of the obtained light-transmitting sheet is 70
%, and the integrated near-infrared light transmittance was 31%.

Example 3 A biaxially stretched polyester film with a thickness of 75 μm was used as the substrate (A), and a 10 Å thick layer was applied as the first layer on it (A).
titanium oxide layer and 55 Å thick silver film layer and 20 Å thick
A metal thin film layer (B) having a pre-treatment layer and a post-treatment layer consisting of a titanium oxide layer of
75% ethyl acetate solution of 800Å trimethylpropane and 2,4-tolylene diisocyanate adduct (manufactured by Nippon Polyurethane Co., Ltd.: trade name Coronate L)
and a transparent dielectric layer (C) of a crosslinked polymer made of polyester resin (manufactured by Toyobo Co., Ltd.: trade name Vylon RV-200), and a pretreatment layer (C) made of titanium oxide, the same as the first layer, as the third layer. A light-transmitting sheet with the configuration (A)/(B)/(C)/(B), which is formed by sequentially laminating each layer consisting of a metal thin film layer (B) consisting of a silver thin film layer with a post-treatment layer, is prepared as follows. Created in.

The pre-treatment layer and post-treatment layer consisting of a metal thin film layer (B) with a thickness of 10 Å and a titanium oxide layer with a thickness of 20 Å were prepared by DC magnetron sputtering using titanium metal as a target at an Ar gas pressure of 5×10 ^-3 Torr. A metallic titanium film was formed underneath and exposed to the atmosphere to form a titanium oxide layer.

A silver thin film layer having a thickness of 55 Å as the metal thin film layer (B) was formed by DC magnetron sputtering using a silver plate as a target under an argon gas pressure of 5×10 ^-3 Torr.

The transparent dielectric layer (C) consists of 1 part of Vylon RV-200, 0.1 part of Coronate L, 3 parts of methyl ethyl ketone,
Byron RV-200 was dissolved at 2% by weight in a mixed solvent consisting of 1 part of cyclohexanone,
It was obtained by coating with a bar coater and drying at 130°C for 3 minutes.

The integrated visible transmittance of the obtained light-transmitting sheet was 73
%, and the integrated near-infrared light transmittance was 39%.

Example 4 A biaxially stretched polyester film with a thickness of 125 μm was used as the substrate (A), and a first layer with a thickness of 80 Å was formed on the substrate (A).
The second layer is a transparent dielectric layer (C) made of epoxy resin with a thickness of 750 Å.
(A)／(B)／Sequentially laminated with a metal thin film layer (B), which is a silver-gold thin film layer containing 20% by weight of gold and has the same thickness of 80 Å.
A light-transmitting sheet having the configuration (C)/(B) was prepared as follows.

The first and third silver-gold thin film layers of the metal thin film layer (B) were prepared by using a silver-gold alloy target containing 20% gold by DC magnetron spacing under an Ar gas pressure of 3×10 ^-3 Torr. Formed with ivy rings.

Transparent dielectric layer (C) made of epoxy resin as the second layer
is a bisphenol-based epoxy resin (manufactured by Ciel Kagaku Co., Ltd., trade name Epicote 1004) and a polyamide-based curing agent (manufactured by Daiichi General Co., Ltd., trade name Versamide).
125) was weighed at the same weight ratio, dissolved in a mixed solvent consisting of 1 part of toluene and 1 part of diacetone alcohol so that the epoxy resin was 1.5% by weight, coated with a bar coater, and dried at 130°C for 5 minutes. .

The integral visible light transmittance of the obtained light-transmitting sheet is
The integrated near-infrared light transmittance was 31%.

Example 5 On the light-transmitting sheet obtained in Example 3, a methyl isobutyl ketone solution (10 parts of A-310, A-10 (2 parts) was coated with a bar coater and dried in the air, forming a protective layer (D) to a thickness of
A 25 μm polypropylene stretched film was laminated. The resulting light-transmissive sheet laminated with the protective layer (D) had an integrated visible light transmittance of 73%, an integrated visible light reflectance of 11%, and an integrated near-infrared light transmittance of 36%.

Example 6 A light-transmitting sheet was constructed in the same manner as in Example 4, except that the transparent dielectric layer (C) of Example 4 was formed from a crosslinked polymer of polyester polyurethane resin.

The crosslinked polymer made of polyester polyurethane resin is made by chain-extending polyethylene adipate, which has an average molecular weight of 1300 and has hydroxyl groups at both ends, with 2,4-tolylene diisocyanate.
40000 polyester polyurethane resin and 0.4 part of Coronate L used in Example 3 were dissolved in ethyl acetate so that the polyester polyurethane resin was 1.7% by weight, and then coated with a bar coater.
It was obtained by drying at 130°C for 3 minutes.

The integrated visible transmittance of the obtained light-transmitting sheet is 72
%, and the integrated near-infrared light transmittance was 40%.

Claims (1)

[Claims] 1. A metal thin film layer (B) with a thickness of 40 Å to 300 Å, a transparent dielectric layer (C) with a thickness of 200 Å to 3000 Å, and a transparent protective layer (D) on at least one side of the organic polymer film (A).
(A)／(B)／(C)／(B) or (A)／(B)／(C)／(B)／(D
1.) A light-transmitting sheet formed by laminating layers in the order of (C), wherein the transparent dielectric layer (C) is made of an organic crosslinked polymer.