JP2015001571A - Infrared reflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared reflection film giving enough heat insulation without re-radiating infrared rays, which solves such a problem that a conventional polyethylene terephthalate (PET) surface protective film itself absorbs external irradiation light and reflected light from an infrared reflection layer to elevate temperature, and thereby, sufficient heat insulation is not obtained.SOLUTION: An infrared reflection film 10 comprises an infrared reflection layer 11, a transparent film 12, and an adhesive layer 13. The infrared reflection layer 11 has two major surfaces; the transparent film 12 is composed of a polymer film essentially comprising a {-(C-CCN)n-} skeleton (polyacrylonitrile skeleton) and supports one major surface of the infrared reflection layer 11; and the adhesive layer 13 is formed on the other major surface of the infrared reflection layer 11.

Description

  The present invention relates to an infrared reflective film.

  The infrared reflective film 100 shown in FIG. 2 is known conventionally (patent document 1). FIG. 2 is a cross-sectional view of a conventional infrared reflective film 100. In the infrared reflective film 100, an infrared reflective layer 102, a photocatalytic functional layer 103, and a surface protective film 104 are laminated in this order on one surface of a transparent thermoplastic resin film 101, and an adhesive layer 105 is disposed on the other surface of the thermoplastic resin film 101. Is a laminated body.

  The thermoplastic resin film 101 is a base film serving as a base for lamination, and a polyethylene terephthalate (PET) film is preferably used. The infrared reflecting layer 102 is a laminated film in which a metal thin film layer is sandwiched between transparent dielectric layers having a high refractive index. The infrared reflection layer 102 allows visible light to pass but reflects near infrared rays to far infrared rays. The infrared reflective layer 102 is formed by a sputtering method.

  The photocatalytic functional layer 103 has a self-purifying action that reduces the number of cleanings of the infrared reflective film 100. At the same time, the photocatalytic functional layer 103 protects the infrared reflective layer 102. The photocatalytic function layer 103 is formed by a sputtering method.

  When the infrared reflective film 100 is affixed to a plate glass 106 such as a window, and the film surface is rubbed with a tool such as a squeegee and adhered while removing water and bubbles, if the surface protective film 104 is not present, the photocatalytic function layer 103 is scratched. Prone to occur. The surface protective film 104 prevents the photocatalytic function layer 103 from being scratched. As the surface protective film 104, a polyethylene terephthalate (PET) film is preferably used.

  The infrared reflective film 100 is attached to a window of a building, a vehicle or the like and used to improve the effect of air conditioning. Moreover, the infrared reflective film 100 is affixed on the window of a freezing / refrigeration showcase, and is used also for improving the cold insulation effect.

  When a polyethylene terephthalate (PET) film is used as the surface protective film 104, since the polyethylene terephthalate (PET) contains many C═O groups, C—O groups, and aromatic groups, a far infrared region having a wavelength of 5 μm to 25 μm. Vibration absorption often occurs.

  Since the infrared reflective film 100 uses a polyethylene terephthalate (PET) film as the surface protective film 104, the surface protective film 104 includes infrared light included in the irradiation light 107 from the outside and infrared light included in the reflected light of the infrared reflective layer 102. The surface protection film 104 itself easily re-radiates infrared rays (this means that the surface protection film 104 has a high infrared emissivity).

  As a result, the infrared reflective film 100 using a polyethylene terephthalate (PET) film as the surface protective film 104 has a problem that it is difficult to obtain sufficient heat insulation.

  Most heat-resistant polymer films on which a metal thin film or a dielectric thin film can be formed on the surface by sputtering are easy to absorb and absorb infrared rays in the far-infrared region, like polyethylene terephthalate (PET). An infrared reflective film using such a polymer film as a base film or a protective film has a high infrared emissivity, and it is difficult to obtain sufficient heat insulation. Polymer film materials with high heat resistance and low infrared emissivity are rare and little is known.

JP 2000-334876 A

  With the conventional infrared reflective film 100 using a polyethylene terephthalate (PET) film as the surface protective film 104, it is difficult to obtain sufficient heat insulation. Most polymer films having heat resistance, like polyethylene terephthalate (PET), tend to vibrate and absorb infrared rays in the far infrared region. Therefore, an infrared reflective film using such a polymer film as a base film or a protective film has a high infrared emissivity and it is difficult to obtain sufficient heat insulation.

  An object of the present invention is to adopt a transparent polymer film made of a material that does not absorb infrared rays in the far infrared region while having heat resistance such that a metal thin film or a dielectric thin film can be formed on the surface by a sputtering method. It is to obtain an infrared reflective film having a simple structure and sufficient heat insulation.

(1) The infrared reflective film of the present invention includes an infrared reflective layer, a transparent film, and an adhesive layer. The infrared reflecting layer has two main surfaces. The transparent film is a polymer film having a {-(C-CCN) n-} skeleton (polyacrylonitrile skeleton) as a main component. The transparent film supports one main surface of the infrared reflecting layer. The adhesive layer is formed on the other main surface of the infrared reflecting layer.
(2) In the infrared reflective film of the present invention, the polymer film having a {-(C-CCN) n-} skeleton (polyacrylonitrile skeleton) as a main component is a polyacrylonitrile (PAN) film.
(3) In the infrared reflective film of the present invention, the adhesive layer is made of an acrylic pressure-sensitive adhesive.
(4) The vertical emissivity of the infrared reflective film of the present invention is 0.4 or less.
(5) In the infrared reflective film of the present invention, the infrared reflective layer is composed of a multilayer laminated film of a metal thin film and a high refractive index dielectric thin film.
(6) In the infrared reflective film of the present invention, the metal thin film of the infrared reflective layer is made of gold, silver, copper, aluminum, palladium, or an alloy thereof.
(7) In the infrared reflective film of the present invention, the refractive index of the high refractive index dielectric thin film of the infrared reflective layer is 1.8 to 2.7.
(8) In the infrared reflective film of the present invention, the high refractive index dielectric thin film of the infrared reflective layer is made of indium tin oxide (ITO), titanium oxide, zirconium oxide, tin oxide, indium oxide, zinc oxide or It consists of these combinations.

  In the infrared reflective film of the present invention, the transparent film is a polymer film having a {-(C-CCN) n-} skeleton (polyacrylonitrile skeleton) as a main component, and thus has a high heat insulating property while having a simple configuration. .

(A) Cross-sectional view of the infrared reflective film of the present invention, (b) Cross-sectional view of the infrared reflective film of the comparative example Sectional view of conventional infrared reflective film Explanatory drawing of thermal insulation measuring device for infrared reflective film

[Infrared reflective film]
Fig.1 (a) is sectional drawing of the infrared reflective film 10 of this invention. The infrared reflective film 10 includes an infrared reflective layer 11, a transparent film 12 that supports one main surface of the infrared reflective layer 11, and an adhesive layer 13 formed on the other main surface of the infrared reflective layer 11.

  The entire surface of the transparent film 12 is covered with the infrared reflective layer 11. In actual use, the infrared reflective film 10 is attached to, for example, a plate glass 14 via the adhesive layer 13.

  The transparent film 12 supports the main surface of the infrared reflective layer 11 and also serves as a protective layer for the infrared reflective layer 11. Therefore, a special protective layer for protecting the infrared reflecting layer 11 is not necessary. For this reason, the infrared reflective film 10 of this invention has few layers, a structure is simple, and a film thickness is thin.

  The transparent film 12 is made of a polymer film having a {— (C—CCN) n—} skeleton (polyacrylonitrile skeleton) as a main component. Unlike polyethylene terephthalate (PET), a polymer film having a {-(C-CCN) n-} skeleton (polyacrylonitrile skeleton) as a main component does not have a C—O bond, and thus far infrared rays having a wavelength of 5 μm to 25 μm. Vibration absorption does not occur.

  For this reason, the infrared far-infrared region included in the irradiation light 15 from the outside reaches the infrared reflecting layer 11 with almost no absorption by the transparent film 12. As a result, when infrared rays pass through the transparent film 12, the transparent film 12 hardly absorbs infrared rays.

  Infrared rays are reflected by the infrared reflecting layer 11, pass through the transparent film 12 again, and exit to the outside. Also at this time, the transparent film 12 hardly absorbs infrared rays that pass therethrough.

  In this way, the infrared emissivity of the transparent film 12 can be kept low. The vertical emissivity of the infrared reflective film of the present invention is preferably 0.4 or less, more preferably 0.2 or less. High heat insulation is obtained by the infrared reflective film 10 of the present invention. Although the infrared reflective film 10 of this invention is a simple structure, it has heat insulation and a weather resistance.

  FIG. 1B shows a transparent film made of a polyethylene terephthalate (PET) film instead of the transparent film 12 made of a polymer film having a {-(C-CCN) n-} skeleton (polyacrylonitrile skeleton) as a main component. It is sectional drawing of the infrared reflective film 20 of the comparative example which used 22 as a support film.

  The infrared reflective film 20 includes an infrared reflective layer 21, a transparent film 22 that supports one main surface of the infrared reflective layer 21, and an adhesive layer 23 formed on the other main surface of the infrared reflective layer 21. The entire surface of the transparent film 22 is covered with the infrared reflective layer 21. In actual use, the infrared reflective film 20 is attached to, for example, a plate glass 24 via the adhesive layer 23.

  Molecules constituting the polyethylene terephthalate (PET) of the transparent film 22 absorb and absorb infrared rays in the far infrared region. For this reason, the infrared rays in the far-infrared region included in the irradiation light 25 from the outside are absorbed by the transparent film 22 and a portion that is not absorbed reaches the infrared reflecting layer 21.

  Infrared rays are reflected by the infrared reflecting layer 21, pass through the transparent film 22 again, and exit to the outside. Since the transparent film 22 absorbs part of the reflected infrared rays, the temperature of the transparent film 22 further increases.

  As a result, the transparent film 22 itself re-radiates infrared rays. For this reason, the infrared emissivity of the transparent film 22 becomes high, and in the infrared film 20 of the comparative example, high heat insulation cannot be obtained.

[Infrared reflective layer]
The infrared reflecting layer 11 used in the present invention transmits visible light and reflects infrared light. The visible light transmittance of the infrared reflection layer 11 alone is preferably 50% or more. The vertical emissivity of the infrared reflection layer 11 alone is preferably 0.1 or less. A method for measuring the vertical emissivity will be described later.

  The infrared reflecting layer 11 is usually a multilayer film formed by laminating a large number of metal thin films and high refractive index dielectric thin films such as titanium dioxide and zirconium dioxide. The material for forming the metal thin film is, for example, gold, silver, copper, aluminum, palladium, or an alloy thereof. The thickness of the metal thin film is preferably adjusted in the range of 5 nm to 1,000 nm so that both the visible light transmittance and the infrared reflectance are increased.

  The high refractive index dielectric thin film preferably has a refractive index in the range of 1.8 to 2.7. As a material for forming the high refractive index dielectric thin film, indium tin oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, zinc oxide, or a combination thereof is used. The thickness of the high refractive index dielectric thin film is preferably adjusted in the range of 20 nm to 80 nm.

  The metal thin film and the high refractive index dielectric thin film are formed by, for example, sputtering, vacuum deposition, plasma CVD, or the like. By these methods, the infrared reflective layer 11 can be adhered and laminated on the transparent film 12. The side in contact with the transparent film 12 may be either a metal thin film or a high refractive index dielectric thin film.

[Transparent film]
The transparent film 12 used in the present invention is made of a polymer film having a {-(C-CCN) n-} skeleton (polyacrylonitrile skeleton) as a main component. A polymer film having a {-(C-CCN) n-} skeleton (polyacrylonitrile skeleton) as a main component has low absorption in the far-infrared region. Therefore, by adjusting the thickness of the transparent film 12, for example, the minimum transmittance of light in the wavelength range of 5 μm to 25 μm (far infrared region) can be increased (for example, 50% or more).

  The polymer mainly composed of a {— (C—CCN) n—} skeleton (polyacrylonitrile skeleton) used for the transparent film 12 is preferably polyacrylonitrile (PAN). Polyacrylonitrile (PAN) has little absorption in the infrared region and is excellent in heat insulation and weather resistance. A small amount of styrene, acrylic, or the like may be copolymerized with polyacrylonitrile (PAN). Alternatively, a polymer mainly composed of a {-(C-CCN) n-} skeleton (polyacrylonitrile skeleton) used for the transparent film 12 is represented by the following chemical formulas (A), (B), (C) A nitrile rubber compound containing a structure represented by

In the formulas (A), (B), and (C), R ₁ is hydrogen or a methyl group, and R _{2 to} R ₅ are each independently hydrogen, a linear or branched alkyl having 1 to 4 carbon atoms. Or a straight-chain or branched alkenyl group having 1 to 4 carbon atoms. The nitrile rubber is obtained, for example, by copolymerizing acrylonitrile and / or a derivative thereof and 1,3-butadiene. Further, a hydrogenated nitrile rubber in which a double bond derived from 1,3-butadiene is partially or completely hydrogenated can also be used.

  The thickness of the transparent film 12 is preferably 5 μm to 150 μm. There exists a possibility that the supportability of the infrared reflective layer 11 may fall that the thickness of the transparent film 12 is less than 5 micrometers. On the other hand, when the thickness of the transparent film 12 exceeds 150 μm, the absorption in the infrared region cannot be ignored, and the heat insulating property may be lowered.

[Adhesive layer]
The infrared reflective film 10 of the present invention is attached to an object (for example, a plate glass 14) that is expected to have a heat insulating effect via an adhesive layer 13. The adhesive layer 13 used in the present invention is not particularly limited, but is preferably an acrylic pressure-sensitive adhesive. The acrylic pressure-sensitive adhesive is obtained by reacting a copolymer of an alkyl acrylate ester having an alkyl group with about 2 to 10 carbon atoms with a crosslinking agent containing polyisocyanate or melamine resin. The thickness of the adhesive layer 13 is preferably 1 μm to 50 μm.

  As the polyacrylonitrile (PAN) film used in Examples and Comparative Examples, a film obtained by the following procedure was used. A polyacrylonitrile (PAN) resin (manufactured by Aldrich) was dissolved in dimethylformamide, and this polyacrylonitrile (PAN) resin solution was applied onto a polyethylene terephthalate (PET) film (manufactured by Mitsubishi Plastics) using an applicator. Next, the coating film was dried in an air circulation oven at 150 ° C. to obtain a polyacrylonitrile (PAN) film on a polyethylene terephthalate (PET) film. Polyacrylonitrile (PAN) films were prepared to the thickness of each polyacrylonitrile (PAN) film by controlling the concentration of the applied polyacrylonitrile (PAN) solution and the applicator gap. The polyacrylonitrile (PAN) film used other than Example 1 was used after peeling from the polyethylene terephthalate (PET) film.

[Example 1]
An infrared reflective layer was obtained by alternately laminating an ITO film having a thickness of 35 nm and an APC film having a thickness of 15 nm on a polyacrylonitrile (PAN) film having a thickness of 5 μm formed on PET by RF magnetron sputtering. . The ITO film is an indium tin oxide film, and the APC film is an alloy film of 98 wt% silver, 1 wt% palladium, and 1 wt% copper. Next, an acrylic pressure-sensitive adhesive layer having a thickness of 15 μm is formed on the surface of the infrared reflective layer by a transfer method, a glass plate having a thickness of 1.1 mm is bonded through the pressure-sensitive adhesive layer, and then the PET film is peeled off. An infrared reflector was obtained. Table 1 shows the vertical emissivity and the heat insulation test results.

[Example 2]
An infrared reflector was obtained by the same method as in Example 1 except that the thickness of the polyacrylonitrile (PAN) film was 10 μm. Table 1 shows the vertical emissivity and the heat insulation test results.

[Example 3]
An infrared reflector was obtained in the same manner as in Example 2 except that the thickness of the polyacrylonitrile (PAN) film was 22 μm. Table 1 shows the vertical emissivity and the heat insulation test results.

[Example 4]
An infrared reflector was obtained in the same manner as in Example 2 except that the thickness of the polyacrylonitrile (PAN) film was 40 μm. Table 1 shows the vertical emissivity and the heat insulation test results.

[Example 5]
An infrared reflecting plate was obtained in the same manner as in Example 2 except that the thickness of the polyacrylonitrile (PAN) film was 22 μm and the infrared reflecting layer was an aluminum film having a thickness of 20 nm. Table 1 shows the vertical emissivity and the heat insulation test results.

[Example 6]
An infrared reflector was obtained in the same manner as in Example 2 except that the thickness of the polyacrylonitrile (PAN) film was 22 μm and the infrared reflective layer was a 20 nm thick gold-aluminum film. Table 1 shows the vertical emissivity and the heat insulation test results.

[Comparative Example 1]
An infrared reflector was obtained in the same manner as in Example 2 except that a 25 μm thick polyethylene terephthalate (PET) film was used as the transparent film. Table 1 shows the vertical emissivity and the heat insulation test results.

[Comparative Example 2]
An infrared reflector was obtained in the same manner as in Comparative Example 1 except that a PET film having a thickness of 100 μm was used as the transparent film. Table 1 shows the vertical emissivity and the heat insulation test results.

[Measuring method]
[Vertical emissivity]
Using a Varian Fourier transform infrared spectrometer (FT-IR) equipped with a variable angle reflection accessory, the regular reflectance of infrared light having a wavelength of 5 μm to 25 μm was measured, and JIS R 3106-2008 (sheet glass) The vertical emissivity was determined according to the test method of transmittance, reflectance, emissivity, and solar heat gain.

[Visible light transmittance]
Visible light transmittance was measured according to JIS A 5759-2008 (film for architectural window glass).

[Thermal insulation properties]
The adhesive layer 13 of the infrared reflective film 10 was stuck to the opening part of the heat insulation box 30 provided with the heater 31 and the thermocouple 32 shown in FIG. 3, and the heat insulation box 30 was made into the airtight state. The inner method of the heat insulation box 30 is 10 cm × 10 cm × 14 cm. The inside of the heat insulation box 30 was heated with a heater 31 with a constant output, and the temperature inside the heat insulation box 30 at a location 1 cm away from the infrared reflective film 10 was measured with a thermocouple 32. The better the heat insulating property of the infrared reflective film 10, the higher the temperature in the heat insulating box 30. The heat insulating property was evaluated based on the temperature in the heat insulating box 30.

  There is no restriction | limiting in particular in the use of the infrared reflective film 10 of this invention. The infrared reflective film 10 of the present invention is attached to, for example, a window for a building or a vehicle, a transparent case for storing plants, a frozen or refrigerated showcase, to improve the heating / cooling effect and prevent rapid temperature changes. Used for.

DESCRIPTION OF SYMBOLS 10 Infrared reflective film 11 Infrared reflective layer 12 Transparent film 13 Adhesive layer 14 Plate glass 15 Irradiated light 20 Infrared reflective film 21 Infrared reflective layer 22 Transparent film 23 Adhesive layer 24 Flat glass 25 Irradiated light 30 Heat insulation box 31 Heater 32 Thermocouple 100 Infrared reflective film DESCRIPTION OF SYMBOLS 101 Transparent thermoplastic resin film 102 Infrared reflective layer 103 Photocatalyst functional layer 104 Surface protection film 105 Adhesive layer 106 Plate glass 107 Irradiation light

Claims (8)

An infrared reflective layer having two main surfaces;
A transparent film made of a polymer film mainly comprising a {-(C-CCN) n-} skeleton (polyacrylonitrile skeleton) that supports one main surface of the infrared reflective layer;
The infrared reflective film provided with the contact bonding layer formed in the other main surface of the said infrared reflective layer.   The infrared reflective film of Claim 1 whose polymer film which has the said {-(C-CCN) n-} frame | skeleton (polyacrylonitrile frame | skeleton) as a main component is a polyacrylonitrile (PAN) film.   The infrared reflective film according to claim 1, wherein the adhesive layer is made of an acrylic pressure-sensitive adhesive.   The infrared reflective film in any one of Claims 1-3 whose vertical emissivity of the said infrared reflective film is 0.4 or less.   The infrared reflective film in any one of Claims 1-4 in which the said infrared reflective layer consists of a multilayer laminated film of a metal thin film and a high refractive index dielectric thin film.   The infrared reflective film according to claim 5, wherein the metal thin film is made of gold, silver, copper, aluminum, palladium, or an alloy thereof.   The infrared reflective film according to claim 5 or 6, wherein the high refractive index dielectric thin film has a refractive index of 1.8 to 2.7.   8. The high refractive index dielectric thin film is made of indium tin oxide (ITO), titanium oxide, zirconium oxide, tin oxide, indium oxide, zinc oxide, or a combination thereof. Infrared reflective film as described in 2.

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