heat-insulating film

Abstract

The object of the present disclosure is to provide a heat-insulating film having an infrared absorption layer having infrared absorption, scratch resistance, and antifouling properties. The heat-insulating film (1) comprises a transparent substrate (3) having a retardation value of 100 nm or less and an infrared absorption layer (2) superimposed on the transparent substrate (3). The infrared absorption layer (2) is a cured product of an ultraviolet-curable resin composition. The ultraviolet-curable resin composition contains an oxide (A) having infrared absorption ability, an acrylic compound (B) that does not contain fluorine, and an acrylic compound (C) that contains fluorine.

Description

Technology Field

[0001] The present disclosure relates to a heat-insulating film. More specifically, it relates to a heat-insulating film that makes it difficult to transmit infrared rays. Background Technology

[0002] Patent Document 1 discloses an optical laminate formed by laminating an infrared shielding layer formed from an infrared absorbing adhesive composition and a polarizing film. This infrared absorbing adhesive composition contains infrared absorbing microparticles, an acrylic copolymer, and a dispersant. This acrylic copolymer is obtained by copolymerizing a monofunctional acrylic compound such as n-butyl acrylate and acrylic acid. Prior art literature

[0003] International Publication No. 2016 / 152843

[0004] The object of the present disclosure is to provide a heat-insulating film having an infrared absorption layer having infrared absorption, scratch resistance, and antifouling properties.

[0005] A heat-insulating film according to the present disclosure comprises a transparent substrate having a retardation value of 100 nm or less and an infrared absorption layer superimposed on the transparent substrate. The infrared absorption layer is a cured product of an ultraviolet-curable resin composition. The ultraviolet-curable resin composition comprises an oxide (A) having infrared absorption ability, an acrylic compound (B) that does not contain fluorine, and an acrylic compound (C) that contains fluorine. Brief explanation of the drawing

[0006] [Fig. 1] Fig. 1 is a cross-sectional view showing an example of a heat-insulating film according to a first embodiment. [Fig. 2] Fig. 2 is a cross-sectional view showing another example of a heat-insulating film according to the first embodiment. [Fig. 3] Fig. 3A is a cross-sectional view showing a first example of a heat-insulating film according to a second embodiment. Fig. 3B is a cross-sectional view showing a second example of a heat-insulating film according to a second embodiment. Fig. 3C is a cross-sectional view showing a third example of a heat-insulating film according to a second embodiment. [Fig. 4] Fig. 4A is a cross-sectional view showing a first example of a heat-insulating film according to a third embodiment. Fig. 4B is a cross-sectional view showing a second example of a heat-insulating film according to a third embodiment. [Fig. 5] Fig. 5 is a cross-sectional view showing an example of a heat-insulating film according to a fourth embodiment. [Fig. 6] Figs. 6A and 6B are conceptual diagrams showing a projection device mounted on a moving body. Specific details for implementing the invention

[0007] First, a summary of the circumstances leading to the present disclosure will be explained with reference to FIGS. 6A and FIGS. 6B.

[0008] In recent years, technology has been actively developed to enable a user (200) to safely drive a vehicle (300), such as a car or airplane, by mounting a projection device (10) on the vehicle (300) and displaying driving support information from a display unit (11) as an image (21) on the windshield (20).

[0009] However, if the cover (14) of the projection device (10) is not equipped with the heat-insulating film (1) described later, there is a possibility of destruction due to heat generation as the display unit (11) is concentrated by the infrared light (62), ultraviolet light (63), and visible light (64) included in the natural light (61) from the sun (6) passing through the windshield (20) and the cover (14), particularly the infrared light (62) and visible light (64) which account for most of the thermal energy, being reflected from the mirror (13) toward the display unit (11).

[0010] In addition, when the projection device (10) is mounted on the moving body (300), dust or contaminants are likely to adhere to the cover (14), and by removing them, for example with a cloth, scratches may occur on the surface of the cover (14), and the quality of the projected virtual image (23) may deteriorate as a result.

[0011] Thus, as a result of the aforementioned research, the inventors discovered a heat-insulating film (1) that is easy to transmit visible light (64) which affects the quality of the brightness of the projected virtual image (23), while being difficult to transmit infrared light (62), and has antifouling and scratch-resistant properties, and thus reached the present disclosure.

[0012] The heat-insulating film (1) comprises a transparent substrate (3) having a retardation value of 100 nm or less and an infrared absorption layer (2) superimposed on the transparent substrate (3) (see FIG. 1). The infrared absorption layer (2) is a cured product of an ultraviolet curable resin composition (hereinafter referred to as composition (X)). The composition (X) contains an oxide (A) having infrared absorption ability, an acrylic compound (B) that does not contain fluorine in one molecule, and an acrylic compound (C) that contains fluorine in one molecule.

[0013] The heat-insulating film (1) has infrared absorption properties due to oxide (A). When the cover (14) is equipped with the heat-insulating film (1), infrared light (62) is difficult to pass through the heat-insulating film (1), so the display part (11) is less likely to be damaged and the projection device (10) is less likely to be deformed. In addition, the infrared absorption layer (2) has scratch resistance due to acrylic compound (B) and antifouling properties due to acrylic compound (C). Because of this, it is difficult for contamination to adhere to the surface of the infrared absorption layer (2). Even if the contamination attached to the surface of the infrared absorption layer (2) is wiped off with a cloth, the surface of the infrared absorption layer (2) is less likely to be scratched. In addition, by having a retardation value of 100 nm or less of the transparent substrate (3), the decrease in brightness or rainbow stains of the projected virtual image (23) are prevented, and it is also difficult to cause an additional decrease in brightness when viewed through a polarizing member such as polarizing sunglasses.

[0014] Hereinafter, embodiments according to the present disclosure will be described in more detail. Meanwhile, in the following description, "(meth)acryl-" means at least one of "acryl-" and "methacryl-". For example, "(meth)acryl monomer" means at least one of "acryl monomer" and "methacryl monomer".

[0015] <First Embodiment>

[0016] (Heat-reflective film)

[0017] The heat-insulating film (1) according to the present embodiment has the property of insulating heat by blocking the transmission of infrared light (62). The heat-insulating film (1) comprises an infrared absorption layer (2) and a transparent substrate (3) as shown in FIG. 1. The infrared absorption layer (2) is overlapped with the transparent substrate (3). Such an infrared absorption layer (2) and a transparent substrate (3) form a laminate (1A). That is, the heat-insulating film (1) comprises a laminate (1A) having an infrared absorption layer (2) on the surface of a transparent substrate (3). In the present embodiment, the heat-insulating film (1) is composed only of the laminate (1A), but the heat-insulating film (1) may additionally comprise any layer other than the infrared absorption layer (2) and the transparent substrate (3).

[0018] The heat-insulating film (1) according to the present embodiment preferably has an infrared light transmittance of 30% or less at a wavelength of 800 nm or more and 2500 nm or less, and an total light transmittance of 60% or more. Accordingly, the heat-insulating film (1) can suppress the transmission of infrared light to ensure a heat-insulating effect while also ensuring transparency, thereby suppressing the decrease in visibility through the heat-insulating film (1).

[0019] (Infrared absorption layer)

[0020] Next, the infrared absorption layer (2) is described.

[0021] The infrared absorption layer (2) is a layer having the property of absorbing infrared light (62) and is a cured product of composition (X). Composition (X) contains an oxide (A) having infrared absorption ability, an acrylic compound (B) that does not contain fluorine in one molecule, an acrylic compound (C) that contains fluorine in one molecule, and a photopolymerization initiator (D).

[0022] Oxide (A) is a compound that imparts infrared absorption properties to the infrared absorption layer (2). The infrared absorption capacity of oxide (A) means that when the light transmittance of a mixture in which oxide (A) is dispersed in a transparent resin is measured by a spectrophotometer, the transmittance of light with a wavelength of 550 nm is 75% or more, and the transmittance of light with a wavelength of 1000 nm is 50% or less. As conditions for obtaining this infrared absorption capacity, for example, the ratio of oxide (A) to the mixture is 5 mass% or more and 85 mass% or less, and the thickness of the mixture is 0.3 μm or more and 30 μm or less. It is preferable that the infrared absorption capacity of oxide (A) has a transmittance of light with a wavelength of 550 nm of 80% or more and a transmittance of light with a wavelength of 1000 nm of 40% or less. The infrared absorption capacity of the oxide (A) is more preferably such that the transmittance of light with a wavelength of 550 nm is 80% or more, and the transmittance of light with a wavelength of 1000 nm is 10% or less. As a transparent resin contained in the above mixture, for example, a multifunctional acrylate polymer can be used.

[0023] Meanwhile, in the present disclosure, the spectrophotometer used to measure light transmittance and light reflectance is not particularly limited, but for example, the UH4150 (product model) manufactured by Hitachi High-Tech Science Co., Ltd. may be used.

[0024] The oxide (A) contains at least one compound selected from the group consisting of, for example, antimony tin oxide (ATO), indium tin oxide (ITO), and cesium tungsten oxide. Among these, it is preferable that the oxide (A) contains cesium tungsten oxide. The component having a wavelength within the range of 800 nm to 1200 nm included in the infrared light (62) has a high intensity of thermal energy, and cesium tungsten oxide can absorb this component more than ATO and ITO. For this reason, cesium tungsten oxide can improve the infrared absorption of the infrared absorption layer (2).

[0025] When the oxide (A) contains tungsten cesium oxide, it is preferable that the oxide (A) contains 30 mass% or more of tungsten cesium oxide. That is, it is preferable that the ratio of tungsten cesium oxide to the oxide (A) be 30 mass% or more. More preferably, the ratio of tungsten cesium oxide to the oxide (A) is 60 mass% or more, even more preferably 80 mass% or more, and particularly preferably 90 mass% or more. The upper limit of the ratio of tungsten cesium oxide is not specifically limited, but is, for example, 100 mass% or less.

[0026] Since it is desirable for the infrared absorption layer (2) to have transparency, it is desirable for the particle size of the oxide (A) contained in the infrared absorption layer (2) to be in the range of 1 nm or more and 200 nm or less. In this case, the oxide (A) in the infrared absorption layer (2) becomes difficult to see, making it easier to obtain an infrared absorption layer (2) with excellent transparency. It is more desirable for the particle size of the oxide (A) to be in the range of 5 nm or more and 100 nm or less, and it is even more desirable for the particle size of the oxide (A) to be in the range of 10 nm or more and 50 nm or less. Meanwhile, in the present disclosure, the particle size is obtained from the particle size distribution using a laser diffraction / scattering particle size distribution measuring device.

[0027] The acrylic compound (B) is a compound that imparts scratch resistance to the infrared absorption layer (2) and contains (meth)acryloyl groups. Examples of such acrylic compounds (B) include uretain (meth)acrylate, epoxy (meth)acrylate, and polyester (meth)acrylate.

[0028] It is preferable that the acrylic compound (B) is a compound containing three or more acryloyl groups as functional groups. In this case, since a cross-linked structure derived from the acryloyl groups of the acrylic compound (B) exists in the cured product of the composition (X), the scratch resistance of the infrared absorption layer (2) can be improved. The acrylic compound (B) is a trifunctional acrylate such as, for example, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, tris 2-hydroxyethyl isocyanurate tri(meth)acrylate, glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, and ditrimethylolpropane tri(meth)acrylate; It comprises at least one compound selected from the group consisting of tetrafunctional acrylates such as pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and dipentaerythritol tetra(meth)acrylate; pentfunctional acrylates such as dipentaerythritol penta(meth)acrylate and ditrimethylolpropane penta(meth)acrylate; hexfunctional acrylates such as dipentaerythritol hexa(meth)acrylate and ditrimethylolpropane hexa(meth)acrylate; and polyfunctional (meth)acrylate compounds in which a group among these acrylates is substituted with an alkyl group or ε-caprolactone. Among these, it is preferable that the acrylate compound (B) contains a hexfunctional acrylate. In this case, the scratch resistance of the infrared absorption layer (2) can be further improved, and scratches on the surface of the infrared absorption layer (2) can be suppressed even if the total amount of the acrylic compound (B) is reduced. It is more preferable that the acrylic compound (B) contains 6-function acrylate and acrylate other than 6-function. The acrylic compound (B) may include any compound, not limited to the above group.

[0029] Acrylates other than those with 6 functions may contain acrylates with 3 to 5 functions. Acrylates other than those with 6 functions may contain acrylates with more than 6 functions. Examples of acrylates with more than 6 functions include polypentaerythritol polyacrylate (specifically, Aronix M-400 series manufactured by Doa Synthetic Co., Ltd., Viscote #802 manufactured by Osaka Organic Chemical Industry Co., Ltd., etc.), dendrimer acrylate (specifically, Viscote #1000 manufactured by Osaka Organic Chemical Industry Co., Ltd., etc.), and uretane acrylates with more than 6 functions (specifically, Luxidia V-4000BA manufactured by DIC Co., Ltd., and UV-1700B manufactured by Nippon Synthetic Chemical Industry Co., Ltd., etc.).

[0030] When the acrylic compound (B) contains hexafunctional acrylate, it is preferable that the acrylic compound (B) contains 10 mass% or more of hexafunctional acrylate. In this case, the scratch resistance of the infrared absorption layer (2) can be further improved, and scratches on the surface of the infrared absorption layer (2) can be suppressed even if the total amount of the acrylic compound (B) is reduced.

[0031] The acrylic compound (C) is a compound that imparts antifouling properties to the infrared absorption layer (2). The acrylic compound (C) is preferably a compound containing a polymerizable functional group and a fluoroalkyl group. It is more preferable that the acrylic compound (C) contains an ethylenically unsaturated group as a polymerizable functional group. The polymerizable functional group in the acrylic compound (C) may consist only of (meth)acryloyl groups, and the acrylic compound (C) may additionally contain at least one group selected from the group consisting of vinyl groups, allyl groups, and styryl groups as a polymerizable functional group.

[0032] The acrylic compound (C) is, for example, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3,3-pentafluoropropyl (meth)acrylate, 1H,1H-perfluoro-n-butyl (meth)acrylate, 1H,1H-perfluoro-n-pentyl (meth)acrylate, 1H,1H-perfluoro-n-hexyl (meth)acrylate, 1H,1H-perfluoro-n-octyl (meth)acrylate, 1H,1H-perfluoro-n-decyl (meth)acrylate, 1H,1H-perfluoro-n-dodecyl (meth)acrylate, 1H,1H-perfluoroisobutyl (meth)acrylate, 1H,1H-perfluoroisooctyl (meth)acrylate, 1H,1H-perfluoroisododecyl (Meth)acrylate, 2,2,3,3-Tetrafluoropropyl (Meth)acrylate, 1H,1H,5H-Perfluoropentyl (Meth)acrylate, 1H,1H,7H-Perfluoroheptyl (Meth)acrylate, 1H,1H,9H-Perfluorononyl (Meth)acrylate, 1H,1H,11H-Perfluoroundecyl (Meth)acrylate, 3,3,3-Trifluoropropyl (Meth)acrylate, 3,3,4,4,4-Pentafluorobutyl (Meth)acrylate, 2-(Perfluoro-n-propyl)ethyl (Meth)acrylate, 2-(Perfluoro-n-Butyl)ethyl (Meth)acrylate, 2-(Perfluoro-n-Hexyl)ethyl (Meth)acrylate, 2-(Perfluoro-n-Octyl)ethyl (Meth)acrylate, It comprises at least one compound selected from the group consisting of 2-(perfluoro-n-decyl)ethyl (meth)acrylate, 2-(perfluoroisobutyl)ethyl (meth)acrylate, 2-(perfluoroisooctyl)ethyl (meth)acrylate, 3,3,4,4-tetrafluorobutyl (meth)acrylate, 1H,1H,6H-perfluorohexyl (meth)acrylate, 1H,1H,8H-perfluorooctyl (meth)acrylate, 1H,1H,10H-perfluorodecyl (meth)acrylate, 1H,1H,12H-perfluorododecyl (meth)acrylate, and pentaerythritol diacrylate difluorobutyrate.The acrylic compound (C) may include any compound, not limited to the above group.

[0033] The acrylic compound (C) may be a perfluoropolyether acrylate compound. It is preferable that this perfluoropolyether acrylate compound has a perfluoroalkyl group as a main chain and also has a polymerizable functional group at the end of the main chain or at the side chain. By containing the fluorine-containing acrylic compound (C), the infrared absorption layer (2) has reduced surface tension, making it easier to repel water and oil, and thus improves antifouling properties. Additionally, by containing the acrylic compound (C), the surface of the infrared absorption layer (2) is imparted slip properties, making it easier to lower the coefficient of friction, and thus making it easier to wipe off dirt and also making it difficult to get scratches when wiping.

[0034] The photopolymerization initiator (D) is a compound that absorbs ultraviolet light and initiates a polymerization reaction in the composition (X). Examples of photopolymerization initiators (D) include acetophenones, benzophenones, α-aminooxime esters, thioxantones, etc. The composition (X) may contain a photosensitizer in addition to the photopolymerization initiator (D) or instead of the photopolymerization initiator (D). Examples of photosensitizers include n-butylamine, triethylamine, tri-n-butylphosphine, thioxantone, etc.

[0035] Composition (X) may additionally contain a reactive diluent. Examples of reactive diluents include single-function monomers such as ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, methylstyrene, and N-vinylpyrrolidone, and multi-function monomers such as trimethylolpropane tri(meth)acrylate, hexanediol (meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate.

[0036] The composition (X) may additionally contain any additives such as a dispersant. It is preferable that the composition (X) additionally contain a UV absorber (E).

[0037] The ultraviolet absorber (E) is not particularly limited, but examples include organic ultraviolet absorbers such as benzotriazole compounds, triazine compounds, benzophenone compounds, salicylic acid compounds, and benzoyl compounds, or inorganic ultraviolet absorbers such as zinc oxide and titanium oxide. By including the ultraviolet absorber (E), it is possible to shield ultraviolet light (63) in addition to infrared light (62) contained in natural light (61) with the infrared absorption layer (2), thereby further suppressing the temperature rise of the display part (11). In addition, by including the ultraviolet absorber (E), the deterioration of the resin of the infrared absorption layer (2) and the transparent substrate (3) is prevented, which is also effective in improving the durability of the heat-insulating film (1).

[0038] The ratio of oxide (A) to the infrared absorption layer (2) is preferably 5 mass% or more. The upper limit of the ratio of oxide (A) is not specifically limited, but is, for example, 80 mass% or less. The infrared absorption layer (2) is preferably 5 mass% or more of oxide (A). The upper limit of the ratio of oxide (A) to the infrared absorption layer (2) is not specifically limited, but is, for example, 80 mass% or less. It is more preferable that the infrared absorption layer (2) contains 30 mass% or more and 40 mass% or less of oxide (A) with respect to the total amount. Meanwhile, the infrared absorption layer (2) is formed from a solid component (non-volatile component) included in the composition (X).

[0039] The ratio of the acrylic compound (B) to the composition (X) is preferably 10 mass% or more. The ratio of the acrylic compound (B) to the composition (X) is more preferably 15 mass% or more. The upper limit of the ratio of the acrylic compound (B) is not particularly limited, but is, for example, 90 mass% or less. The ratio of the acrylic compound (B) to the total amount of the composition (X) is more preferably 60 mass% or more and 70 mass% or less.

[0040] The ratio of the acrylic compound (C) to the composition (X) is preferably 0.1 mass% or more and 10 mass% or less. The ratio of the acrylic compound (C) to the total amount of the composition (X) is more preferably 0.5 mass% or more and 6 mass% or less.

[0041] A composition (X) is applied, for example, onto a transparent substrate (3), and an infrared absorption layer (2) can be formed by irradiating the composition (X) with ultraviolet light and photocuring it. Any method, such as roll coating, spin coating, or dip coating, is employed for the application of the composition (X).

[0042] The thickness of the infrared absorption layer (2) is preferably 0.3 μm or more and 30 μm or less. If the thickness of the infrared absorption layer (2) is 0.3 μm or more, the infrared absorption layer (2) has mechanical strength even if it does not contain a filler, and can suppress cracks in the infrared absorption layer (2) during the production of the heat-insulating film (1). Meanwhile, the "filler" mentioned here is different from the oxide (A) mentioned above. If the thickness of the infrared absorption layer (2) is 30 μm or less, it can suppress bending of the heat-insulating film (1) caused by bending the transparent substrate due to shrinkage when the composition (X) hardens, and it can also suppress peeling caused by stress between the infrared absorption layer (2) and the transparent substrate (3) caused by the bending of the heat-insulating film (1). In addition, it can suppress cracking that occurs when the bent heat-insulating film attempts to deform in a direction opposite to the direction of bending. The bending of the heat-insulating film (1) can be suppressed, thereby making it difficult for the adhesion between the infrared absorption layer (2) and the transparent substrate (3) to decrease, and also making it easier to handle in the next process. The thickness of the infrared absorption layer (2) is more preferably 1.0 μm or more and 15 μm or less, and more preferably 2.0 μm or more and 7.0 μm or less. For example, when the heat-insulating film (1) is a part of an in-vehicle device of a vehicle, the heat-insulating film (1) may be attached while bending along a curved surface in order to prevent light from outside the vehicle from reflecting toward the driver. In such a case, if the thickness of the infrared absorption layer (2) is thicker than 30 μm, the flexibility of the infrared absorption layer (2) is low, and there is a risk that cracks may form in the infrared absorption layer (2) which is a coating film.

[0043] It is preferable that the infrared absorption layer (2) has a visible light transmittance of 60% or more, and thereby the transparency of the heat-insulating film (1) is easily obtained, so that the decrease in visibility through the heat-insulating film (1) can be reduced. In addition, it is preferable that the infrared absorption layer (2) has an infrared transmittance of 30% or less, and thereby a heat-insulating effect can be imparted to the heat-insulating film (1).

[0044] In addition, it is more desirable to have both visible light transmittance and infrared transmittance. Specifically, it is desirable that the transmittance of light with a wavelength of 550 nm is 60% or more and the transmittance of light with a wavelength of 1000 nm is 50% or less, more desirable that the transmittance of light with a wavelength of 550 nm is 75% or more and the transmittance of light with a wavelength of 1000 nm is 30% or less, and more desirable that the transmittance of light with a wavelength of 550 nm is 80% or more and the transmittance of light with a wavelength of 1000 nm is 10% or less.

[0045] (Transparent entry)

[0046] Next, the transparent substrate (3) is described.

[0047] The heat-insulating film (1) is provided with a transparent substrate (3) as described above. The transparent substrate (3) is a film-like material with a retardation value of 100 nm or less. Because of this, the virtual image (23) projected through the heat-insulating film (1) is less likely to develop rainbow stains. In addition, since the influence on linear polarization from the display unit (11) can be minimized, the virtual image (23) projected through the heat-insulating film (1) can obtain brightness as designed. Furthermore, even when the axis angle of polarization is adjusted with the assumption that the projected virtual image (23) is viewed through a polarizing material such as polarizing sunglasses, the influence on polarization can be minimized, thereby preventing further reduction in brightness. The lower limit of this retardation value is not specifically limited, but is, for example, 0 nm or greater.

[0048] The retardation value of the transparent substrate (3) is preferably 50 nm or less, and more preferably 30 nm or less. If the retardation value of the transparent substrate (3) is 50 nm or less, it is more difficult for rainbow stains to occur and the brightness is more stable compared to the case where the retardation value exceeds 50 nm and is 100 nm or less. Meanwhile, "the retardation value of the transparent substrate (3) is 100 nm or less" means that the retardation value of the transparent substrate (3) is 100 nm or less in each of the thickness direction, width direction, and length direction of the transparent substrate (3).

[0049] The transparent substrate (3) is obtained by molding a transparent material. Examples of materials constituting the transparent substrate (3) include glass, cycloolefin polymer (hereinafter referred to as COP), polycarbonate (hereinafter referred to as PC), triacetylcellulose (hereinafter referred to as TAC), and polymethyl acrylate (hereinafter referred to as PMMA). Among these, it is preferable that the transparent substrate (3) contains at least one type selected from the group consisting of PC, COP, and PMMA. In this case, impact resistance can be imparted to the heat-insulating film (1), particularly the transparent substrate (3), and furthermore, the transparent substrate (3) can make it difficult to break the heat-insulating film (1). That is, a transparent substrate (3) with low retardation and impact resistance is obtained.

[0050] It is more preferable that the transparent substrate (3) contains PC and PMMA. In this case, the transparent substrate (3) may be formed as a laminate having multiple layers, and may include a layer containing PC (hereinafter referred to as a PC layer) and a layer containing PMMA (hereinafter referred to as a PMMA layer). For example, the transparent substrate (3) may be a laminate consisting of two layers, where one layer is a PC layer and the other layer is a PMMA layer. In addition, the transparent substrate (3) may be a laminate consisting of three layers, where two layers are PMMA layers and the remaining one layer is a PC layer, and one layer of PC may be located between the two layers of PMMA layers. That is, the transparent substrate (3) consisting of three layers is formed such that one layer of PMMA is provided on each of the two surfaces of the PC layer.

[0051] When the transparent substrate (3) is a laminate having multiple layers, it is preferable that the infrared absorption layer (2) be formed on the surface of a layer containing polymethyl acrylate. For example, as shown in FIG. 2, when the transparent substrate (3) is a two-layer structure in which the transparent substrate (3) is a laminate of a layer containing polycarbonate (PC layer) (31) and a layer containing polymethyl acrylate (PMMA layer) (32), the infrared absorption layer (2) is formed on the surface of the PMMA layer (32), and the infrared absorption layer (2) does not need to be formed on the surface of the PC layer (31). When the infrared absorption layer (2) is formed on the surface of the PMMA layer (32), the infrared absorption layer (2) is supported by the PMMA layer (32), making it easier to function as a hard coat layer. For example, the infrared absorption layer (2) formed on the surface of the PMMA layer (32) can achieve a pencil hardness of 3H or higher. Therefore, the scratch resistance of the heat shield film (1) can be improved.

[0052] Meanwhile, in this embodiment, the infrared absorption layer (2) is not excluded from being formed on the surface of the PC layer (31). When the infrared absorption layer (2) is formed on the surface of the PC layer (31), the pencil hardness of the infrared absorption layer (2) is slightly reduced (about 3B), making it difficult to improve the scratch resistance of the heat-insulating film (1), but it does not impair the original function (infrared absorption function) of the infrared absorption layer (2).

[0053] In the case where the transparent substrate (3) has a two-layer structure consisting of a PC layer and a PMMA layer, the ratio of the thickness of the PC layer to the thickness of the PMMA layer is preferably PC layer thickness / PMMA layer thickness = 99 / 1 to 51 / 49. In this case, impact resistance can be imparted to the heat-insulating film (1), particularly the transparent substrate (3), and furthermore, the transparent substrate (3) can make it difficult to break the heat-insulating film (1). More preferably, PC layer thickness / PMMA layer thickness = 97 / 3 to 75 / 25. Specifically, for example, the thickness of the PC layer can be 345 μm and the thickness of the PMMA layer can be 30 μm.

[0054] The transparent substrate (3) may contain any compound, not limited to the above. The transparent substrate (3) may additionally contain additives such as antioxidants, heat stabilizers, and ultraviolet absorbers.

[0055] The thickness of the transparent substrate (3) is preferably 20 μm or more and 1000 μm or less. In this case, cracks in the transparent substrate (3) can be suppressed during the production of the heat-insulating film (1), and mechanical strength can also be increased. In addition, the thickness of the transparent substrate (3) is more preferably 50 μm or more and 550 μm or less, and even more preferably 100 μm or more and 500 μm or less.

[0056] The thickness (total thickness) of the heat-insulating film (1) is preferably 50 μm or more and 700 μm or less. Since reducing the thickness of the heat-insulating film (1) can reduce double images of the image displayed on the display, it is preferable for the heat-insulating film (1) to be thin. More preferably, the thickness of the heat-insulating film (1) can be 100 μm or more and 550 μm or less, and more preferably 150 μm or more and 500 μm or less. Therefore, mechanical strength can be increased, and in addition, when the heat-insulating film is used as a single unit without a support, deformation may become a problem due to the future increase in the size of the projection device, so this can also serve as a countermeasure.

[0057] Meanwhile, the thickness of the heat-insulating film (1) refers to the sum of the thicknesses of all layers constituting the heat-insulating film (1) (total thickness). Accordingly, the thickness of the heat-insulating film (1) composed of a transparent substrate (3) and an infrared absorption layer (2) is the sum of the thickness of the transparent substrate (3) and the thickness of the infrared absorption layer (2). As described later, the thickness of the heat-insulating film (1) composed of a transparent substrate (3), an infrared absorption layer (2), and an anti-reflection layer (4) is the sum of the thickness of the transparent substrate (3), the thickness of the infrared absorption layer (2), and the thickness of the anti-reflection layer (4). In addition, the thickness of the heat-insulating film (1) composed of a transparent substrate (3), an infrared absorption layer (2), and a polyester film (5) is the sum of the thickness of the transparent substrate (3), the thickness of the infrared absorption layer (2), and the thickness of the polyester film (5). In addition, the thickness of the heat-blocking film (1) composed of a transparent substrate (3), an infrared absorption layer (2), and a polarization layer (7) is the sum of the thickness of the transparent substrate (3), the thickness of the infrared absorption layer (2), and the thickness of the polarization layer (7).

[0058] (use)

[0059] Next, the use of the heat-insulating film (1) is explained.

[0060] The heat-insulating film (1) can be applied to various components requiring heat insulation. Examples of such components include an optical component constituting the optical system of a projection device (10); a windshield, side window, and rear window of a moving body (300); a polarizing lens; a window of a building; a sensor, etc. Examples of optical components of the projection device (10) include a cover (14) (see FIG. 6B).

[0061] Hereinafter, a case in which a heat-insulating film (1) is provided in a projection device (10) such as FIG. 6B will be described. This description is merely an example of various forms for carrying out the present disclosure.

[0062] The projection device (10) is mounted on a moving body (300), such as a car (see FIG. 6A). The projection device (10) is provided within the dashboard of the moving body (300) or on the dashboard.

[0063] The projection device (10) comprises a display unit (11), an infrared absorber (12), a mirror (13), a cover (14), and a case (16). Such a projection device (10) is also called a head-up display (HUD).

[0064] The case (16) has an internal space and forms the external shape of the projection device (10). The case (16) accommodates an infrared absorber (12), a mirror (13), and a cover (14) in its internal space. The case (16) has an opening at the top, and a cover (14) is provided in this opening.

[0065] The original role of the cover (14) is to prevent dust from entering the interior space through the upper opening of the case (16). In addition, as a performance requirement for the cover (14), there is wear resistance, which is assumed to be the case where the user (200) wipes off dust or contaminants attached to the surface of the cover (14) over time, or heat resistance required for the vehicle, so polycarbonate resin is conventionally used. However, with the recent increase in the size of the projection device (10), the amount of natural light (61) intruding into the projection device has increased, and as the concern about destruction of the display unit (11) due to heat generation has increased, a countermeasure against sunlight has also become required for the cover (14). In the prior art, it has been reported that a polarizing plate is provided as the cover (14) to make it difficult to transmit visible light (64) among the natural light (61), thereby serving as a countermeasure against sunlight. In this embodiment, a heat-insulating film is provided as a cover (14) to make it difficult to transmit infrared light (62) among natural light (61), thereby serving as a countermeasure against sunlight.

[0066] The cover (14) may be provided with a base (15) and a heat-insulating film (1) overlaid on the base (15). The base (15) is an optical member that is thicker than the heat-insulating film (1) and transmits visible light. Examples of materials constituting the base (15) include glass, cycloolefin polymer, polycarbonate, and polymethyl acrylate.

[0067] The display unit (11) is configured to display driving support information. This driving support information passes through an infrared absorber (12) and is reflected by a mirror (13). The driving support information reflected by the mirror (13) passes through a cover (14) and is projected onto a windshield (20) as an image (21). As a result, the user (200) inside the vehicle (300) sees the image (21) on the windshield (20) as a virtual image (23) projected into the space in front (outside the vehicle) of the vehicle (300). That is, the user (200) driving the vehicle (300) can see the virtual image (23) superimposed on the real space extending in front of the vehicle (300). The display unit (11) is, for example, a liquid crystal display (LCD).

[0068] The infrared absorber (12) is a plate-shaped member that transmits visible light and also absorbs infrared light (62). By having the projection device (10) equipped with the infrared absorber (12), even if the infrared light (62) passes through the cover (14), the infrared light (62) can be absorbed by the infrared absorber (12). As a result, it becomes less likely for the display part (11) to be damaged by the infrared light (62). The infrared absorber (12) is, for example, a member in which an infrared absorber is dispersed in a resin. As this infrared absorber, a compound such as an oxide (A) can be used.

[0069] The mirror (13) reflects driving support information from the display unit (11) onto the windshield (20). Such a mirror (13) is, for example, a concave mirror. There may be multiple mirrors (13), and they are called the first mirror or the second mirror.

[0070] In the interior of the movable body (300) of the present embodiment, both the projection device (10) and the heat-insulating film (1) may be provided. The heat-insulating film (1) is a component provided separately from the cover (14) of the projection device (10) and is provided on the upper surface of the dashboard. The heat-insulating film (1) may be part of the dashboard or separate from the dashboard. By providing the heat-insulating film (1) on the upper surface of the dashboard, it becomes possible to find the combined performance of the heat-insulating film and the performance of the component other than the heat-insulating film provided on the cover (14). Meanwhile, the heat-insulating film (1) is provided in front of the cover (14) and also near the lower end of the windshield (20).

[0071] <Second Embodiment>

[0072] Next, the heat-insulating film (1) according to the present embodiment will be described with reference to FIGS. 3A to 3C. In the following description, components that overlap with the first embodiment are given the same reference numerals in the drawings, and specific descriptions may be omitted.

[0073] The heat-insulating film (1) may have an infrared absorption layer (2), a transparent substrate (3), and one or two anti-reflection layers (4), as shown in FIGS. 3A to 3C. The infrared absorption layer (2) and the transparent substrate (3) form a laminate (1A).

[0074] The anti-reflection layer (4) is a layer that prevents light that hits its surface from being reflected.

[0075] When the heat-insulating film (1) has one anti-reflection layer (4), the anti-reflection layer (4) is overlapped on one side of the heat-insulating film (1). In the case of the heat-insulating film (1) as in FIG. 3A, the anti-reflection layer (4) is overlapped on the surface of a transparent substrate (3) that is not adjacent to the infrared absorption layer (2) in the thickness direction of the laminate (1A). When the projection device (10) is equipped with such a heat-insulating film (1), since the anti-reflection layer (4) faces the mirror (13), it is possible to suppress further reflection of driving support information (visible light) reflected from the mirror (13) on the surface of the anti-reflection layer (4). By doing so, the efficiency of visible light transmitting through the heat-insulating film (1) can be improved. In addition, it is also effective as a countermeasure against double images caused by reflection between the outer and inner sides in the thickness direction of the member.

[0076] In addition, in the case of a heat-insulating film (1) as in FIG. 3B, an anti-reflection layer (4) is superimposed on the surface of an infrared absorption layer (2) that is not adjacent to a transparent substrate (3) in the thickness direction of the laminate (1A). When a projection device (10) equipped with such a heat-insulating film (1) is mounted on a movable body (300), the anti-reflection layer (4) faces the windshield (20), so natural light (61) transmitted through the windshield (20) is difficult to reflect from the surface of the anti-reflection layer (4). Because of this, it is possible to suppress the natural light (61) reflected from the surface of the anti-reflection layer (4) from entering the eyes of the user (200) who is driving, or the virtual image (23) from being visible.

[0077] In addition, as shown in FIG. 3C, when the heat-insulating film (1) is equipped with two anti-reflection layers (4), the anti-reflection layers (4) are overlapped on both sides of the heat-insulating film (1). When a projection device (10) equipped with such a heat-insulating film (1) is mounted on a movable body (300), the anti-reflection layer (4) overlapped with the transparent substrate (3) faces the mirror (13), so driving support information (visible light) reflected from the mirror (13) can be suppressed from being further reflected from the surface of the anti-reflection layer (4). By doing so, the efficiency of visible light passing through the heat-insulating film (1) can be improved. Furthermore, since the anti-reflection layer (4) overlapped with the infrared absorption layer (2) faces the windshield (20), natural light (61) passing through the windshield (20) becomes difficult to reflect from the surface of the anti-reflection layer (4).

[0078] As shown in FIG. 3B, when the heat-insulating film (1) has an anti-reflection layer (4) on one side, compared to the case where it does not have an anti-reflection layer (4), the light reflectance of the surface (laminated surface) of the heat-insulating film (1) on the anti-reflection layer (4) side can be reduced to 2% or less, and the light transmittance can be improved to 4% or more. Also, as shown in FIG. 3C, when the heat-insulating film (1) has an anti-reflection layer (4) on both sides, compared to the case where it does not have an anti-reflection layer (4), the light reflectance of the surface of the anti-reflection layer (4) of the heat-insulating film (1) can be reduced to 1% or less, and the light transmittance can be improved to 8% or more. By doing so, for example, the light efficiency of the light source of the HUD can be increased by 8%. The heat-insulating film (1) having an anti-reflection layer (4) on at least one side has a double image prevention effect.

[0079] The thickness of the anti-reflection layer (4) is preferably 0.05 μm or more and 0.15 μm or less. In this case, it is difficult to reflect light with a wavelength of about 550 nm from the surface of the anti-reflection layer (4). As a result, even if this light is slightly reflected from the surface of the anti-reflection layer (4), the reflected light becomes difficult to see by the user (200). The thickness of the anti-reflection layer (4) is more preferably 0.08 μm or more. In addition, the thickness of the anti-reflection layer (4) is more preferably 0.12 μm or less. Particularly preferably, the thickness of the anti-reflection layer (4) is 0.10 μm.

[0080] The anti-reflection layer (4) comprises a low refractive index layer (4A). The anti-reflection layer (4) may consist only of the low refractive index layer (4A), or may comprise any layer other than the low refractive index layer (4A).

[0081] The low refractive index layer (4A) is a layer whose refractive index is lower than that of the transparent substrate (3). The low refractive index layer (4A) is a cured product of a composition (e.g., a coating agent) containing a binder material. If the binder material itself has a low refractive index, the refractive index can be adjusted by the binder material alone, but low refractive index particles may also be incorporated into the binder material.

[0082] Examples of binder materials include hydrolysates of silicon alkoxides, saturated hydrocarbons, or polymers having polyethers as the main chain (ultraviolet-curing resins, thermosetting resins). Additionally, fluorine atoms may be included within the constituent units of these polymers.

[0083] The low refractive index particles may include, for example, silica microparticles; and at least one selected from the group consisting of fluoride microparticles such as magnesium fluoride, lithium fluoride, aluminum fluoride, calcium fluoride, and sodium fluoride. It is preferable that the silica microparticles include hollow silica microparticles.

[0084] The low-refractive-index particles may be surface-treated to facilitate compatibility with binder materials.

[0085] In forming the low refractive index layer (4A), any coating method such as roll coating, spin coating, and dip coating may be employed. Then, after applying a composition containing a binder material, the low refractive index layer (4A) is obtained by curing the composition.

[0086] It is preferable that the refractive index of the low refractive index layer (4A) be 1.45 or lower. When the low refractive index layer (4A) comes into contact with air, as the refractive index of the low refractive index layer (4A) decreases, it approaches the refractive index of air (1.0), so light becomes more difficult to reflect from the surface of the anti-reflection layer (4). The lower limit of this refractive index is not specifically limited, but for example, it is 1.30 or higher. If the refractive index of the low refractive index layer (4A) is 1.30 or higher, it is not necessary to make the low refractive index layer (4A) porous to reduce the density for the purpose of increasing the refractive index of the low refractive index layer (4A), so the mechanical strength of the anti-reflection layer (4) can be secured. Meanwhile, when the refractive index of air is set to 1.0 and the refractive index of the transparent substrate (3) is set to 1.65, the ideal refractive index of the low refractive index layer (4A) is 1.28, but the low refractive index layer (4A) defined by this refractive index is prone to becoming porous. Because of this, the density of the low refractive index layer (4A) decreases, and it is assumed that the mechanical strength of the anti-reflection layer (4) also decreases.

[0087] The anti-reflection layer (4) may additionally provide a layer other than the low refractive index layer (4A) as described above. Examples of layers other than the low refractive index layer (4A) include a hard coat layer. When the anti-reflection layer (4) is provided with a hard coat layer, this hard coat layer can improve the mechanical strength of the anti-reflection layer (4). The hard coat layer can be manufactured with any composition and method.

[0088] <Third Embodiment>

[0089] Next, a heat-insulating film (1) according to the present embodiment will be described with reference to FIGS. 4A and FIGS. 4B. In the following description, components that overlap with the first embodiment are given the same reference numerals in the drawings, and specific descriptions may be omitted.

[0090] As shown in FIGS. 4A and 4B, the heat-insulating film (1) comprises an infrared absorption layer (2), a transparent substrate (3), and a polyester film (5) having a retardation value of 6000 nm or more. The infrared absorption layer (2) and the transparent substrate (3) form a laminate (1A). In such a heat-insulating film (1), the laminate (1A) and the polyester film (5) are overlapped with each other.

[0091] A polyester film (5) is overlapped on one side of a laminate (1A), for example. In the case of a heat-insulating film (1) as in FIG. 4A, a polyester film (5) is overlapped on the surface of a transparent substrate (3) that is not adjacent to an infrared absorption layer (2) in the thickness direction of the laminate (1A). In the case of a heat-insulating film (1) as in FIG. 4B, a polyester film (5) is overlapped on the surface of an infrared absorption layer (2) that is not adjacent to an infrared absorption layer (3) in the thickness direction of the laminate (1A).

[0092] By having the heat-blocking film (1) equipped with a polyester film (5), linear polarization emitted from the display unit (11) is converted into circular polarization after passing through the heat-blocking film (1). Therefore, the rainbow stains of the projected virtual image (23) can be reduced by the polyester film (5). In addition, when the linear polarization of the projected virtual image (23) is viewed through polarizing sunglasses, a blackout is likely to occur in the image, but the polyester film (5) can suppress the occurrence of a blackout. Here, "blackout" refers to a phenomenon in which the screen becomes dark and invisible depending on the viewing angle through polarizing sunglasses. Also, since the display light emitted from the display unit (11) is usually an S-polarization component, when the projected virtual image (23) is viewed through polarizing sunglasses, the brightness is reduced and it becomes difficult to see because the S-polarization component is blocked, but by providing the polyester film (5), visibility is improved. The thickness of the polyester film (5) is preferably 10 μm or more and 300 μm or less.

[0093] As a polyester film (5), for example, a super-birefringent PET film can be used, and specifically, Cosmo Shine SRF manufactured by Toyobo Co., Ltd. can be used.

[0094] <Fourth Embodiment>

[0095] Next, the heat-insulating film (1) according to the present embodiment will be described with reference to FIG. 5. In the following description, components that overlap with the first to third embodiments are given the same reference numerals in the drawings, and specific descriptions may be omitted.

[0096] As shown in FIG. 5, the heat-insulating film (1) comprises an infrared absorption layer (2), a transparent substrate (3), and a polarizing layer (7). The transparent substrate (3) comprises a first transparent substrate (310) and a second transparent substrate (320). The infrared absorption layer (2) and the first transparent substrate (310) form a laminate (1A). The polarizing layer (7) is located between the first transparent substrate (310) and the second transparent substrate (320). The polarizing layer (7) is overlapped with an adhesive layer (8) interposed on the surface of the first transparent substrate (310) that is not adjacent to the infrared absorption layer (2) in the thickness direction of the laminate (1A). The adhesive layer (8) is provided to adhere the surface of the first transparent substrate (310) and the surface of the polarizing layer (7). The adhesive layer (8) preferably has the same degree of transparency as the first transparent substrate (310) and can be formed, for example, from a dried or cured acrylic adhesive. Additionally, the polarizing layer (7) is overlapped with the surface of the second transparent substrate (320) in the thickness direction of the laminate (1A) with the adhesive layer (9) interposed therein. The adhesive layer (9) is provided to adhere the surface of the second transparent substrate (320) to the surface of the polarizing layer (7). The second transparent substrate (320) is adhered to the surface of the polarizing layer (7), which is not adjacent to the first transparent substrate (310), by the adhesive layer (9). The adhesive layer (9) is formed in the same way as the adhesive layer (8).

[0097] The heat-insulating film (1) according to the present embodiment has infrared absorption, scratch resistance, and antifouling properties through the infrared absorption layer (2), just like in the first to third embodiments. In addition, by installing the heat-insulating film (1) in an image light output window such that the transmission axis of the polarization layer (7) is parallel to the wavefront of the emitted light from an image forming device that emits polarized light, such as an LCD, through the polarization layer (7), most of the emitted light from the image forming device can be transmitted, thereby maintaining the brightness of the image, and components of the visible light (64) in the incident natural light (61) that are not parallel to the transmission axis of the polarization layer (7) can be shielded, so that in addition to having heat-insulating performance by making it difficult to transmit the infrared light (62) in the natural light (61) of the heat-insulating film itself, it also exhibits excellent effects of having heat-insulating performance for visible light (64).

[0098] A heat-insulating film (1) having a polarizing layer (7) can be manufactured, for example, as follows. First, a pigment such as a dichromatic water-soluble dye or potassium iodide-iodine solution is adsorbed onto a transparent polymer film such as polyvinyl alcohol (PVA), stretched in a uniaxial direction, and then dried to form a polarizing element (polarizing layer (7)). Next, using a suitable adhesive (including an adhesive) that forms adhesive layers (8 and 9), the first transparent substrate (310) and the second transparent substrate (320) on the film are bonded to the polarizing element, thereby clamping the polarizing element by the first transparent substrate (310) and the second transparent substrate (320). Afterward, an infrared absorption layer (2) can be formed on the surface of the first transparent substrate (310) in the same manner as in the first embodiment to form a heat-insulating film (1). Additionally, after forming an infrared absorption layer (2) on the surface of the first transparent substrate (310), the first transparent substrate (310) having the infrared absorption layer (2) formed thereon may be bonded to the polarizing element. Additionally, the infrared absorption layer (2) may be provided on both the first transparent substrate (310) and the second transparent substrate (320).

[0099] The first transparent substrate (310) and the second transparent substrate (320) may each use the transparent substrate (3) described in the first embodiment. Specifically, for example, the first transparent substrate (310) may use a two-layer structure having a PMMA layer (32) and a PC layer (31). Also, the second transparent substrate (320) may be formed from a PC layer (31). In addition, the first transparent substrate (310) and the second transparent substrate (320) may each use a polyvinyl alcohol film, a TAC film, a COP film, a PC film, etc. Furthermore, the heat-insulating film (1) may be formed as an iodine-based polarizing film, a dye-based polarizing film, a color polarizing film, a polyvinylene polarizing film, an infrared polarizing film, an ultraviolet polarizing film, etc., depending on the pigment used.

[0100] The thickness of the polarization layer (7) is not particularly limited, but it is preferable to have a range of 10 μm or more and 150 μm or less. Within this range, the polarization layer (7) can be provided without the thickness (total thickness) of the heat-insulating film (1) becoming excessively thick. It is more preferable to have the thickness of the polarization layer (7) in a range of 20 μm or more and 130 μm or less, and even more preferably, in a range of 30 μm or more and 110 μm or less. In addition, the heat-insulating film (1) having the polarization layer (7) may also have an anti-reflection layer (4) or a polyester film (5) similar to the above. In this case, the anti-reflection layer (4) or the polyester film (5) is overlapped on the surface of the second transparent substrate (320) (the surface not facing the polarization layer (7)).

[0101] Meanwhile, in this embodiment, a heat-insulating film (1) is described in which the transparent substrate (3) consists of a first transparent substrate (310) and a second transparent substrate (320), but it is not limited to this. That is, the transparent substrate (3) may be only one layer. In this case, the heat-insulating film (1) has an infrared absorption layer (2), a transparent substrate (3), and a polarization layer (7). Then, the infrared absorption layer (2) is provided on one side of the transparent substrate (3), and the polarization layer (7) is provided on the other side of the transparent substrate (3) via an adhesive layer (8) to form a heat-insulating film (1).

[0102] <Example of Variation>

[0103] The above embodiments are merely one of various forms for carrying out the present disclosure. The above embodiments may be modified in various ways depending on the design, etc., as long as the purpose of the present disclosure can be achieved.

[0104] In the second embodiment, the anti-reflection layer (4) is in contact with one or both sides of the laminate (1A), but in a modified example, a polyester film (5) may be provided between the anti-reflection layer (4) and the laminate (1A). Specifically, a polyester film (5) may be provided between the anti-reflection layer (4) and the infrared absorption layer (2), or a polyester film (5) may be provided between the transparent substrate (3) and the anti-reflection layer (4).

[0105] In the second embodiment, an anti-reflection layer (4) having a low refractive index layer (4A) and a hard coat layer was described, but the anti-reflection layer (4) is not limited to a two-layer composition of a low refractive index layer (4A) and a hard coat layer. In a modified example, the layer composition of the anti-reflection layer (4) may be three layers or more, and the anti-reflection layer (4) may be a moth-eye film obtained by a surface nanoimprint method. In that case, moth-eye processing may be performed directly on the heat-insulating film (1), or the moth-eye film with completed moth-eye processing may be laminated with an adhesive or the like. Meanwhile, "moth-eye" refers to a structure having an anti-reflection effect in a conical shape with a diameter of about a few nm to 100 nm.

[0106] Examples

[0107] The present disclosure will be explained in detail below by way of examples.

[0108] <Examples and Comparative Examples>

[0109] The components and components used in the examples and comparative examples are shown below.

[0110] {Transparent Absence}

[0111] · PCPMMA: A film-like laminate having a two-layer structure in which a layer containing polycarbonate and a layer containing polymethyl acrylate are overlapped (thickness 375μm to 750μm),

[0112] · PC: Polycarbonate film (thickness 300,000 nm = 300 μm),

[0113] · COP: Film-like cycloolefin polymer (thickness 100,000 nm = 100 μm),

[0114] · Glass: Glass film (thickness 1,000,000 nm = 1 mm),

[0115] · PET: Film-type polyethylene terephthalate (thickness 250,000 nm = 250 μm).

[0116] {Oxide having infrared absorption ability (A)}

[0117] · Oxide 1: Tungsten cesium oxide (Cs 0.33 WO3; a mixture in which oxide 1 is dispersed in an acrylic resin has a transmittance of 80% for light at a wavelength of 550 nm and 20% for light at a wavelength of 1000 nm, and the ratio of oxide 1 to the mixture is 30 mass%).

[0118] · Oxide 2: Antimony tin oxide (a mixture in which Oxide 2 is dispersed in an acrylic resin has a transmittance of 72% for light at a wavelength of 550 nm and a transmittance of 55% for light at a wavelength of 1000 nm, and the ratio of Oxide 2 to the mixture is 30 mass%).

[0119] In the above, air was used as the blank value.

[0120] {Fluorine-free acrylic compound (B)}

[0121] · 6-function acrylate: Dipentaerythritol hexaacrylate (DPE6A manufactured by Kyoei Chemical Co., Ltd.),

[0122] · Acrylates other than 6-function: Pentaerythritol tetraacrylate (PE-4A manufactured by Kyoei Chemical Co., Ltd.).

[0123] {Fluorine-containing acrylic compound (C)}

[0124] "KY-1207" manufactured by Shinetsu Chemical Co., Ltd.

[0125] {Photopolymerization initiator}

[0126] BASF's "Omnirad 127".

[0127] {Anti-reflection layer}

[0128] Anti-reflective film having a hard coat layer and a low refractive index layer overlapping (thickness 100 μm, refractive index of the low refractive index layer is 1.42; “MUAR8” manufactured by Panasonic Corporation.

[0129] {Super-double refractive index layer}

[0130] Polyethylene terephthalate film with a retardation value of 7900 nm (Cosmo Shine SRF manufactured by Toyobo, thickness 80 μm).

[0131] ≪Preparation of UV-curable resin composition≫

[0132] UV-curable resin compositions of each example and comparative example were prepared by mixing the components in the ratios shown in Tables 1 to 3 below.

[0133] [Examples 1–9]

[0134] First, a UV-curable resin composition was applied to the surface of a transparent substrate such that the thickness after curing was 5000 nm. Next, the UV-curable resin composition on the transparent substrate was cured under ultraviolet light. By doing so, a test film was obtained in which an infrared absorption layer, which is a cured product of the UV-curable resin composition, and the transparent substrate were overlapped. In this embodiment, this test film was used as a heat-insulating film.

[0135] [Example 10]

[0136] First, a UV-curable resin composition was applied to the surface of a transparent substrate such that the thickness after curing was 5000 nm. Next, the UV-curable resin composition on the transparent substrate was cured under ultraviolet light. By doing so, a laminate was obtained in which an infrared absorption layer, which is a cured product of the UV-curable resin composition, and the transparent substrate were overlapped. Subsequently, an anti-reflection film was prepared in which a hard coat layer and a low refractive index layer were overlapped. Then, using OCR (silicone-based UV-curable transparent adhesive), an anti-reflection film (anti-reflection layer) was laminated onto the back surface of the transparent substrate to obtain a test film. In this embodiment, this test film was used as a heat-insulating film.

[0137] [Example 11]

[0138] A test film was obtained in the same manner as in Example 10, except that an anti-reflective film (anti-reflective layer) was placed in the laminate so that the infrared absorption layer and the hard coat layer were adjacent. In this example, this test film was used as a heat-insulating film.

[0139] [Example 12]

[0140] First, a UV-curable resin composition was applied to the surface of a transparent substrate such that the thickness after curing was 5000 nm. Next, the UV-curable resin composition on the transparent substrate was cured under ultraviolet light. By doing so, a laminate was obtained in which an infrared absorption layer, which is a cured product of the UV-curable resin composition, and the transparent substrate were overlapped. Subsequently, two anti-reflective films (first and second anti-reflective films) were prepared in which a hard coat layer and a low refractive index layer were overlapped. Then, the first anti-reflective film was laminated with an acrylic adhesive so that the transparent substrate and the hard coat layer were adjacent, and the second anti-reflective film was laminated with an OCR (silicone-based UV-curable transparent adhesive) so that the infrared absorption layer and the hard coat layer were adjacent. By doing so, a test film was obtained. In this embodiment, this test film was used as a heat-insulating film.

[0141] [Example 13]

[0142] A test film was obtained in which a superbirefringence layer was superimposed on one side of a laminate, in the same manner as in Example 10, except that a polyethylene terephthalate film with a retardation value of 7900 nm was used instead of an anti-reflective film. In this example, this test film was used as a heat-insulating film.

[0143] [Example 14]

[0144] A heat-insulating film was prepared with a transparent substrate thickness of 375 μm and other details as described in Table 3.

[0145] [Example 15]

[0146] A heat-insulating film was prepared by setting the amount of composite oxide to 25 mass% and the rest according to the contents listed in Table 3.

[0147] [Example 16]

[0148] A heat-insulating film was prepared by setting the amount of composite oxide to 30 mass% and the rest according to the contents listed in Table 3.

[0149] [Example 17]

[0150] A heat-insulating film was prepared by setting the thickness of the transparent substrate to 450 μm, forming a polarizing layer on the back side (surface of the PC layer) of the transparent substrate, and otherwise according to the contents described in Table 3.

[0151] Meanwhile, the polarization layer was formed using a polarizer of SHC-10U manufactured by Polar Techno.

[0152] [Example 18]

[0153] A heat-insulating film was prepared with a transparent substrate thickness of 750 μm and other details as described in Table 3.

[0154] [Example 19]

[0155] An infrared absorption layer was made on the surface of the PC layer, and the rest was made according to the contents listed in Table 4 to create a heat-insulating film.

[0156] [Comparative Example 1]

[0157] Only a transparent substrate was prepared, and this transparent substrate was used as a test film.

[0158] [Comparative Example 2]

[0159] A test film having a polarizing plate overlaid on a transparent substrate was obtained by attaching a polarizing plate (SHC-10U manufactured by Polar Techno Co., Ltd.) to a transparent substrate using an acrylic adhesive.

[0160] [Comparative Example 3]

[0161] First, a UV-curable resin composition was applied to the surface of a transparent substrate such that the thickness after curing was 5000 nm. Next, the UV-curable resin composition on the transparent substrate (PET film) was cured under ultraviolet light. As a result, a test film was obtained in which the infrared absorption layer, which is the cured product of the UV-curable resin composition, and the transparent substrate were overlapped.

[0162] [Comparative Example 4]

[0163] First, a UV-curable resin composition was applied to the surface of a transparent substrate such that the thickness after curing was 5000 nm. This UV-curable resin composition does not contain a fluorine-containing acrylic compound (C). Next, the UV-curable resin composition on the transparent substrate was cured under ultraviolet light. By doing so, a test film was obtained in which the infrared absorption layer, which is the cured product of the UV-curable resin composition, and the transparent substrate were overlapped.

[0164] Meanwhile, the layer composition and characteristic points of the test films of Examples 1 to 19 and Comparative Examples 1 to 4 are shown below. The layer composition is arranged in a stacking order from the surface of the test film toward the back surface.

[0165] Example 1: Infrared absorption layer / transparent substrate (PMMA layer + PC layer).

[0166] Example 2: Infrared absorption layer / transparent substrate (PMMA layer + PC layer).

[0167] Example 3: Infrared absorption layer / transparent substrate (PMMA layer + PC layer).

[0168] Example 4: Infrared absorption layer / transparent substrate (PMMA layer + PC layer), acrylic compound (B) is formed using hexafunctional acrylate.

[0169] Example 5: Infrared absorption layer / transparent substrate (PC layer), the transparent substrate is only a PC layer.

[0170] Example 6: Infrared absorption layer / transparent substrate (PMMA layer + PC layer), the infrared absorption layer contains about 90 mass% of a composite oxide.

[0171] Example 7: Infrared absorption layer / transparent substrate (PMMA layer + PC layer), the composite oxide is ATO.

[0172] Example 8: Infrared absorption layer / transparent substrate (COP layer), the transparent substrate is only the COP layer.

[0173] Example 9: Infrared absorption layer / transparent substrate (glass layer), the transparent substrate is only a glass layer.

[0174] Example 10: Infrared absorption layer / transparent substrate (PMMA layer + PC layer) / anti-reflection layer.

[0175] Example 11: Anti-reflective layer / infrared absorption layer / transparent substrate (PMMA layer + PC layer).

[0176] Example 12: Anti-reflective layer / infrared absorption layer / transparent substrate (PMMA layer + PC layer) / anti-reflective layer.

[0177] Example 13: Infrared absorption layer / transparent substrate (PMMA layer + PC layer) / ultra-birefringent film.

[0178] Example 14: Infrared absorption layer / transparent substrate (PMMA layer + PC layer).

[0179] Example 15: Infrared absorption layer / transparent substrate (PMMA layer + PC layer).

[0180] Example 16: Infrared absorption layer / transparent substrate (PMMA layer + PC layer).

[0181] Example 17: Infrared absorption layer / transparent substrate (PMMA layer + PC layer) / polarizing layer.

[0182] Example 18: Infrared absorption layer / transparent substrate (PMMA layer + PC layer).

[0183] Example 19: Infrared absorption layer / transparent substrate (PMMA layer + PC layer).

[0184] Comparative Example 1: Transparent substrate (PC layer) only.

[0185] Comparative Example 2: Polarizer / PC layer.

[0186] Comparative Example 3: Infrared absorption layer / transparent substrate (PET layer) / PC layer, a PET film with a retardation value of 4000 nm is used as the transparent substrate.

[0187] Comparative Example 4: Infrared absorption layer / transparent substrate (PMMA layer + PC layer). A UV-curable resin composition that does not contain a fluorine-containing acrylic compound (C) was used.

[0188] ≪Evaluation≫

[0189] The test films of each example and comparative example were evaluated for each of the following test items. The results of this evaluation are shown in Tables 1 to 4.

[0190] <Infrared Transmittance>

[0191] First, the test films of each example and comparative example were installed in an ultraviolet-visible-near-infrared spectrophotometer (UH4150 manufactured by Hitachi High-Tech Science Co., Ltd.). At that time, the test films were installed with the surface of the infrared absorption layer (2) facing the light source. After installation, infrared rays of all wavelengths in the range of 800 to 2500 nm were irradiated onto the test films. Then, the transmittance of each wavelength was calculated by dividing the intensity of the infrared rays transmitted through the test films by the intensity of the infrared rays irradiated onto the test films, and the average value of these transmittances was taken as the infrared transmittance. Meanwhile, in Comparative Example 1, infrared rays were directly irradiated onto a transparent substrate, and in Comparative Example 2, the test films were installed with the surface of the polarizer facing the light source.

[0192] <Total Light Transmittance>

[0193] First, the test films of each example and comparative example were installed in a haze meter (NDH4000 manufactured by Nippon Tenshoku Kogyo Co., Ltd.). At that time, the test films were installed with the surface of the infrared absorption layer (2) facing the light source. After installation, the total light transmittance was calculated in accordance with JIS K 7361. Meanwhile, in Comparative Example 1, visible light was directly irradiated onto a transparent substrate, and in Comparative Example 2, the test films were installed with the surface of the polarizing plate facing the light source.

[0194] <Temperature rise>

[0195] Internal space (volume 1000cm²) 3 A case was prepared having an opening communicating with the internal space. Then, the opening was closed by attaching a test film to its surface. When attaching the test film, the transparent substrate and the infrared absorption layer were arranged in this order to expose the surface of the test film. After closing the opening of the case with the test film, the temperature of the internal space was measured. This temperature was set as the temperature before the test. Next, the lens was irradiated for 45 minutes using a 60W incandescent bulb (Panasonic Corporation RF100V54WD) at 200 lux. Then, the temperature of the internal space was measured immediately after the infrared irradiation ended. This temperature was set as the temperature after the test. The difference between the temperature after the test and the temperature before the test was defined as the temperature rise. Meanwhile, when attaching the test film, the surface of the transparent substrate was exposed in Comparative Example 1, and the surface of the polarizing plate was exposed in Comparative Example 2.

[0196] <Internal Scratch>

[0197] The scratch resistance of the test film surface was evaluated by a steel wool abrasion test. Using a surface property meter (Type 14DR manufactured by Shinto Kagaku Co., Ltd.) as the test device, the steel wool was tested at 100 g / cm² 2While applying the load, after 10 reciprocating cycles at a speed of 3000 mm / min, the presence or absence of scratches on the surface of the test film was visually checked. The steel wool used was #0000 manufactured by Nippon Steel Wool Co., Ltd.

[0198] <Impact Resistance>

[0199] The impact resistance of the test film was evaluated in accordance with JIS K 5600-5-3. Additionally, the presence or absence of cracks in the test film was visually inspected. Cases where the test film had no cracks were designated as A, and cases where it had cracks were designated as B.

[0200] Pencil Hardness

[0201] The pencil hardness of the test film was evaluated based on JIS K 5600-5-4 (scratch hardness).

[0202] <Water Contact Angle>

[0203] A water droplet was dropped onto the surface of a test film, and the contact angle between the surface and the water droplet was measured.

[0204] <Anti-fouling (fingerprint-wiping)>

[0205] Immediately after attaching a fingerprint to the surface of the infrared absorption layer of the test film, the surface was rubbed 10 times back and forth with BEMCOT-M (manufactured by Asahi Kasei Co., Ltd.). Then, a cellophane adhesive tape ("CT24" manufactured by Nichiban Co., Ltd.) was applied to the rubbed area, and the cellophane adhesive tape was peeled off. Afterward, the antifouling properties of the test film surface were evaluated by visually inspecting the area where the cellophane adhesive tape was peeled off from a distance of 40 cm from the surface of the test film. Case A was defined as having no contamination on the area where the cellophane adhesive tape was peeled off, and case B was defined as having contamination.

[0206] Meanwhile, in Examples 11 and 12, a fingerprint was attached to the surface of the anti-reflective layer, in Comparative Example 1, a fingerprint was attached to the surface of a transparent substrate, and in Comparative Example 2, a fingerprint was attached to the surface of a polarizing plate.

[0207] <Anti-fouling (salt-repellent)>

[0208] Salt water was applied to the surface of the infrared absorption layer of a test film. Immediately after applying the salt water, the surface was rubbed 10 times with BEMCOT-M (manufactured by Asahi Kasei Co., Ltd.). Next, the surface of the test film was dried. The antifouling properties of the test film surface were evaluated by visually confirming whether salt was precipitating on the surface of the test film upon drying. Cases where no salt precipitated on the surface of the test film were designated as A, and cases where salt precipitated were designated as B.

[0209] Meanwhile, in Examples 11 and 12, salt water was applied to the surface of the anti-reflection layer, in Comparative Example 1, salt water was applied to the surface of a transparent substrate, and in Comparative Example 2, salt water was applied to the surface of a polarizing plate.

[0210] <Presence or absence of rainbow stains>

[0211] A test film was placed on a liquid crystal screen, and whether rainbow stains were occurring on the test film was evaluated by viewing it through polarized sunglasses. Cases where no rainbow stains occurred on the test film were designated as A, and cases where rainbow stains occurred were designated as B.

[0212] <Presence or Absence of Blackout>

[0213] A test film was installed on a liquid crystal screen, and when viewed through polarized sunglasses, whether a blackout phenomenon (a phenomenon where the test film becomes dark) occurred depending on the viewing angle was evaluated. Cases where no blackout phenomenon occurred on the test film were designated as A, and cases where a blackout phenomenon occurred were designated as B.

[0214] Double Image

[0215] The test film and flat mirror were installed on the liquid crystal screen in this order, and the virtual image reflected on the flat mirror was observed using a camera to evaluate the double image. The case where no double image occurred was designated as S, the case where a double image occurred but the quality was acceptable as A, and the case where a double image occurred and the quality was poor as B.

[0216]

[0217]

[0218]

[0219] Explanation of the symbols

[0220] 1. Heat-insulating film 2 Infrared absorption layer 3 Transparent material

Claims

Claim 1 A heat-insulating film comprising a transparent substrate having a retardation value of 100 nm or less and an infrared absorption layer superimposed on the transparent substrate, wherein the infrared absorption layer is a cured product of an ultraviolet-curable resin composition, and wherein the ultraviolet-curable resin composition comprises an oxide (A) having infrared absorption ability, an acrylic compound (B) not containing fluorine, and an acrylic compound (C) containing fluorine. Claim 2 A heat-insulating film according to claim 1, wherein the transmittance of infrared rays at a wavelength of 800 nm or more and 2500 nm or less is 30% or less, and the transmittance of total light rays is 60% or more. Claim 3 A heat-insulating film according to claim 1 or 2, wherein the oxide (A) contains cesium tungsten oxide, and the ratio of the cesium tungsten oxide to the oxide (A) is 30 mass% or more. Claim 4 A heat-insulating film according to claim 1 or 2, wherein the acrylic compound (B) contains a hexafunctional acrylate, and the ratio of the hexafunctional acrylate to the acrylic compound (B) is 10 mass% or more. Claim 5 A heat-insulating film according to claim 1 or 2, wherein the ratio of the oxide (A) to the UV-curable resin composition is 5 mass% or more and 80 mass% or less, the ratio of the acrylic compound (B) to the UV-curable resin composition is 15 mass% or more and 90 mass% or less, and the ratio of the acrylic compound (C) to the UV-curable resin composition is 0.1 mass% or more and 10 mass% or less. Claim 6 A heat-insulating film according to claim 1 or 2, wherein the transparent substrate comprises at least one selected from the group consisting of polycarbonate, cycloolefin polymer, and polymethyl acrylate. Claim 7 A heat-insulating film according to claim 1 or 2, wherein the transparent substrate comprises a laminate of a layer containing polycarbonate and a layer containing polymethyl acrylate. Claim 8 In claim 7, the infrared absorption layer is a heat-insulating film formed on the surface of a layer containing polymethyl acrylate in the laminate. Claim 9 A heat-insulating film according to claim 1 or 2, wherein the thickness of the infrared absorption layer is 0.3 μm or more and 30 μm or less. Claim 10 A heat-insulating film according to claim 1 or 2, wherein, in a laminate composed of the transparent substrate and the infrared absorption layer, a polyester film having a retardation value of 6000 nm or more is additionally provided on one side of the transparent substrate or on one side of the infrared absorption layer. Claim 11 A heat-insulating film according to claim 1 or 2, wherein, in a laminate composed of the transparent substrate and the infrared absorption layer, an anti-reflection layer is additionally provided on one side of the transparent substrate, one side of the infrared absorption layer, or both sides. Claim 12 In claim 11, the anti-reflection layer comprises a low-refractive-index layer having a refractive index of 1.45 or less, a heat-insulating film. Claim 13 A heat-insulating film according to claim 11, wherein the thickness of the anti-reflection layer is 0.05 μm or more and 0.15 μm or less. Claim 14 A heat-insulating film applied to an optical member constituting the optical system of a projection device, in accordance with claim 1 or 2. Claim 15 A heat-insulating film according to claim 1 or 2, wherein the transparent substrate comprises a first transparent substrate and a second transparent substrate, and further comprises a polarizing layer between the first transparent substrate and the second transparent substrate, and the infrared absorption layer is located on one side of the first transparent substrate that is not adjacent to the polarizing layer.

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