Heat-shielding film, heat-shielding coating material, and coated object

Abstract

Provided is a heat-shielding film having a transmittance of light with wavelengths of 300-800 nm of 50% or greater, characterized by comprising (i) particles and (ii) a resin component and characterized in that the particles and / or the resin component has an anomalous dispersion of refractive index for light having wavelengths of 500-1,000 nm and that the difference in refractive index for light with 500-nm wavelength between the particles and the resin component is smaller than the difference in refractive index for light with 1,000-nm wavelength between the particles and the resin component.

Description

Heat-shielding films, heat-shielding paints, and painted objects

[0001] The present invention relates to a heat-shielding film, a heat-shielding paint, and a coated article.

[0002] A heat-shielding film is a film that has the function of suppressing the temperature rise of components caused by sunlight when used outdoors. The heat-shielding film has heat-shielding properties because it absorbs or reflects infrared light contained in sunlight.

[0003] Among these, a heat-shielding film that reflects infrared light is particularly preferred because of its high heat-shielding properties. A heat-shielding film that reflects infrared light contains a material that reflects infrared light. Examples of materials that reflect infrared light include titanium dioxide, calcium carbonate, and zinc oxide. For example, Patent Document 1 proposes that a heat-shielding paint used to form a heat-shielding coating film contains titanium dioxide having a specific median diameter.

[0004] On the other hand, there is also a great demand for improving the visible light transmittance of heat-shielding films. For example, Patent Document 2 proposes a highly light-transmitting film material that is a multilayer structure having a heat-shielding resin layer and one or more heat-retaining resin layers, and has an overall visible light transmittance of 10 to 50%.

[0005] JP 2013-147571 A JP 2016-16545 A

[0006] Although further improvement in the visible light transmittance of heat-shielding films is desired, there is often a trade-off between the heat-shielding properties and visible light transmittance of heat-shielding films, and it has been difficult to achieve both. For example, if the content of titanium dioxide, a material that reflects infrared light, in the heat-shielding film is reduced in order to increase the visible light transmittance of the heat-shielding film, the infrared light becomes less likely to be reflected, resulting in a decrease in the heat-shielding properties.

[0007] Therefore, an object of the present invention is to provide a heat-shielding film that has high visible light transmittance and high heat-shielding properties. Another object of the present invention is to provide a heat-shielding paint used to form this heat-shielding film, and a coated article having this heat-shielding film.

[0008] That is, according to one aspect of the present invention, there is provided a heat-shielding film having a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less, the heat-shielding film comprising: (i) particles; and (ii) a resin component; one or both of the particles and the resin component have a refractive index with anomalous dispersion for light with a wavelength of 500 nm or more and 1000 nm or less; and the difference in refractive index between the particles and the resin component for light with a wavelength of 500 nm is smaller than the difference in refractive index between the particles and the resin component for light with a wavelength of 1000 nm.

[0009] According to another aspect of the present invention, there is provided a heat-shielding film having a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less, a transmittance of 70% or more for light with a wavelength of 500 nm, and a reflectance of 30% or more for light with a wavelength of 1000 nm.

[0010] According to the present invention, it is possible to provide a heat-shielding film having high visible light transmittance and high heat-shielding properties. Furthermore, according to the present invention, it is possible to provide a heat-shielding paint used for forming this heat-shielding film, and a coated article having this heat-shielding film.

[0011] The present invention will be described in further detail below with reference to preferred embodiments. In the present invention, the term "anomalous dispersion refractive index" refers to a refractive index in which, in the relationship between refractive index and wavelength, the refractive index on the long wavelength side (infrared light region) is greater than the refractive index on the short wavelength side (visible light region). In contrast, the term "normal dispersion refractive index" refers to a refractive index that decreases with increasing wavelength. Furthermore, in this specification, "having an anomalous dispersion refractive index for light with a wavelength of 500 nm or more and 1000 nm or less" may be simply referred to as "having an anomalous dispersion refractive index."

[0012] The present inventors have conducted extensive research to solve the above problems, and as a result have found that, in order to control light reflection on the surfaces of particles contained in a heat-shielding film, it is important to adjust the difference in refractive index between the particles contained in the heat-shielding film and the resin component present around them, which led to the present invention.

[0013] In a first aspect of the present invention, the heat-shielding film has a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less, and the relationship between the difference in refractive index for light of a specific wavelength between the particles contained in the heat-shielding film and the resin component is specified. Specifically, the difference in refractive index between the particles and the resin component for light with a wavelength of 500 nm is adjusted to be smaller than the difference in refractive index between the particles and the resin component for light with a wavelength of 1000 nm. By doing so, light with a wavelength of 1000 nm, which is particularly strong in the infrared light range of sunlight, is more easily reflected due to the large difference in refractive index between the particles contained in the heat-shielding film and the resin component. On the other hand, light with a wavelength of 500 nm, which is particularly strong in the visible light range of sunlight, is less easily reflected due to the small difference in refractive index between the particles contained in the heat-shielding film and the resin component. In this way, by controlling the reflection of light according to wavelength, it is possible to achieve both visible light transmittance and heat-shielding properties. Furthermore, the inventors have discovered that in order to obtain a heat-shielding film with such light reflection properties, it is important that either one or both of the particles and the resin component contained in the heat-shielding film have an anomalous dispersion refractive index for light with a wavelength of 500 nm or more and 1000 nm or less. This allows the difference in refractive index between the particles and the resin component in the visible light region to be smaller than the difference in refractive index in the infrared light region, thereby enabling both visible light transmittance and heat-shielding properties to be achieved. Here, the difference in refractive index between the particles and the resin component for light with a wavelength of 500 nm is preferably 0 or more and 0.10 or less. Furthermore, the difference in refractive index between the resin and the resin component for light with a wavelength of 1000 nm is preferably 0.20 or more.

[0014] In a second aspect of the present invention, the heat-shielding film has a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less, a transmittance of 70% or more for light with a wavelength of 500 nm, and a reflectance of 30% or more for light with a wavelength of 1000 nm. Such a heat-shielding film facilitates the transmission of light with a wavelength of 500 nm, which has particularly high light energy in the visible light region of sunlight, and facilitates the reflection of light with a wavelength of 1000 nm, which has particularly high light energy in the infrared light region of sunlight. As a result, a heat-shielding film can be obtained that achieves both visible light transmittance and heat-shielding properties.

[0015] First Embodiment A heat shielding film, a coating material, and a coated article according to a first aspect will be described below, although the present invention is not limited to the following embodiment.

[0016] [Heat-shielding film] The heat-shielding film in the first embodiment has a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less. This allows light in the visible light region with a wavelength of 300 nm or more and 800 nm or less to pass through, allowing the heat-shielding film to have high visible light transmittance. Furthermore, in order to have higher visible light transmittance, the heat-shielding film preferably has a transmittance of 60% or more, more preferably 70% or more, for light with a wavelength of 300 nm or more and 800 nm or less. Furthermore, there is no particular limit on the upper limit of the transmittance for light with a wavelength of 300 nm or more and 800 nm or less, but it is preferably, for example, 100% or less.

[0017] The heat-shielding film contains (i) particles and (ii) a resin component. Either or both of the particles and the resin component have an anomalous dispersion refractive index for light with a wavelength of 500 nm to 1000 nm. There are no particular limitations on the method by which the particles and the resin component have an anomalous dispersion refractive index for light with a wavelength of 500 nm to 1000 nm. Furthermore, the particles or resin component having an anomalous dispersion refractive index for light with a wavelength of 500 nm to 1000 nm preferably have a refractive index of 1.60 to 2.10 for light with a wavelength of 500 nm, and a refractive index of 1.50 to 1.70 for light with a wavelength of 1000 nm. Furthermore, the difference between the refractive index for light with a wavelength of 500 nm and that for light with a wavelength of 1000 nm for the particles or resin component having an anomalous dispersion refractive index for light with a wavelength of 500 nm to 1000 nm is preferably 0.10 or more. The upper limit of this refractive index difference is not particularly limited, but can be, for example, 0.50 or less.

[0018] The thickness of the heat-shielding film is preferably 1 μm or more, more preferably 5 μm or more, from the viewpoint of heat-shielding properties, and is preferably 1000 μm or less, more preferably 200 μm or less, from the viewpoint of visible light transmittance.

[0019] (Particles) There are no particular limitations on the particles, as long as they can be adjusted so that the transmittance of the heat-shielding film for light having a wavelength of 300 nm or more and 800 nm or less is 50% or more. Examples of particles include calcium carbonate, alumina, zinc oxide, yttrium oxide (Y ２ O ３ ), and diamond. In order to efficiently reflect infrared light, the particles are preferably dispersed in the resin component. In addition, from the viewpoint of achieving both heat insulation and visible light transmittance, the average particle diameter of the particles is preferably 0.2 μm or more and 5.0 μm or less, more preferably 0.3 μm or more and 5.0 μm or less, and even more preferably 1.0 μm or more and 5.0 μm or less. The average particle diameter of the particles is the cumulative 50% particle diameter (D ５０ This "volume-based cumulative 50% particle diameter (D ５０ ")" is the diameter of a particle that is 50% of the total volume of the measured particles in a particle size cumulative curve, calculated from the smallest particle size side, and can be measured using a particle size distribution analyzer using the dynamic light scattering method. Measurement conditions include, for example, Set Zero: 30 seconds, number of measurements: 3, measurement time: 180 seconds, shape: aspherical, and refractive index: 2.60. Furthermore, a particle size analyzer using the dynamic light scattering method (e.g., "UPA-EX150" manufactured by Nikkiso) can be used as the particle size distribution analyzer. Of course, the particle size distribution analyzer and measurement conditions used are not limited to those described above. Furthermore, from the viewpoint of visible light transmittance, the refractive index of the particles at a wavelength of 500 nm is preferably 1.60 or more and 2.00 or less. Furthermore, since the particles have an anomalous dispersion refractive index, the particles may contain an anomalous dispersion material, as described in the resin component section below.

[0020] (Resin Component) There are no particular limitations on the resin component, as long as it can be adjusted so that the transmittance of the heat-shielding film for light with a wavelength of 300 nm or more and 800 nm or less is 50% or more. In this embodiment, if the resin component does not have a refractive index with anomalous dispersion, the resin component is composed of a resin that does not have anomalous dispersion. On the other hand, if the resin component has a refractive index with anomalous dispersion, the resin component is composed of a resin with a refractive index with anomalous dispersion, or a resin and an anomalous dispersion material with a refractive index with anomalous dispersion.

[0021] Examples of the resin include polystyrene, polyethylene, polypropylene, polyester, and polycarbonate. When a resin having an anomalous dispersion refractive index for light with a wavelength of 500 nm or more and 1000 nm or less is used as the resin, the resin preferably has a peak in the wavelength region of 300 nm or more and 500 nm or less, and more preferably has a peak in the wavelength region of 300 nm or more and 400 nm or less, in its spectral absorption spectrum. In order for the resin to have an anomalous dispersion refractive index, the resin preferably has a unit having a benzotriazole skeleton, a unit having a triazine skeleton, or a unit having a benzophenone skeleton.

[0022] Furthermore, from the viewpoint of ease of adjusting the refractive index of anomalous dispersion, the resin component preferably contains a resin and an anomalous dispersion material having a refractive index of anomalous dispersion for light with a wavelength of 500 nm or more and 1000 nm or less. The resin contained in this resin component may be any of those listed in the (Resin) section above, but since the refractive index can be controlled by the anomalous dispersion material, it is preferable to use a resin that does not have a refractive index of anomalous dispersion for light with a wavelength of 500 nm or more and 1000 nm or less.

[0023] The anomalous dispersion material preferably has a peak in the wavelength region of 300 nm to 500 nm in its spectral absorption spectrum, and more preferably has a peak in the wavelength region of 300 nm to 400 nm. Examples of the anomalous dispersion material include organic compounds having an aromatic group or a heterocyclic group. Examples of products that can be used as the anomalous dispersion material include ultraviolet absorbers such as ADK STAB LA-24, ADK STAB LA-29, and ADK STAB LA-F70 manufactured by ADEKA Corporation, and yellow dyes such as Solvent Yellow 162 (SY162). Examples of the anomalous dispersion material include inorganic particles such as titanium oxide, iron oxide, composite particles of iron oxide and silica, and composite particles of iron oxide and alumina. Examples of composite particles of iron oxide and silica include H-type magadiite encapsulating molecular iron oxide, as described in JP 2022-33391 A. Among these, the anomalous dispersion material is preferably at least one selected from the group consisting of iron oxide, composite particles of iron oxide and silica, and composite particles of iron oxide and alumina. Furthermore, when the anomalous dispersion material is inorganic particles, the average particle size of the inorganic particles is preferably 10 nm or more and 200 nm or less, and more preferably 40 nm or more and 100 nm or less. The average particle size of the inorganic particles of this anomalous dispersion material is the cumulative 50% particle size on a volume basis (D ５０ This "volume-based cumulative 50% particle diameter (D ５０ ) can be measured in the same manner as described in the particle section above.

[0024] When the resin component contains an anomalous dispersion material, the content of the anomalous dispersion material in the resin component is preferably 10% by volume or more and 70% by volume or less, based on the content of the resin in the resin composition. By setting the content of the anomalous dispersion material in this range, it is possible to further improve the heat-shielding properties and visible light transmittance.

[0025] [Heat-shielding coating material] The heat-shielding coating material according to a first embodiment is a heat-shielding coating material used to form a heat-shielding film having a transmittance of 50% or more for light having a wavelength of 300 nm or more and 800 nm or less, and contains (i) particles, (ii) a resin component, and (iii) an organic solvent, wherein one or both of the particles and the resin component have an anomalous dispersion refractive index for light having a wavelength of 500 nm or more and 1000 nm or less, and the difference in refractive index between the particles and the resin component for light having a wavelength of 500 nm is smaller than the difference in refractive index between the particles and the resin component for light having a wavelength of 1000 nm.

[0026] The particles and resin components contained in the heat-shielding coating material can be the same as those described above in the heat-shielding film, and therefore a detailed description thereof will be omitted.

[0027] The organic solvent contained in the heat-shielding coating material is not particularly limited as long as it can mix with the particles and resin component. Examples of the organic solvent include toluene, xylene, methyl ethyl ketone, and ethyl acetate.

[0028] The heat-shielding coating material may further contain a dispersant, a surfactant, and a viscosity modifier in addition to the above-mentioned particles, resin component, and organic solvent.

[0029] The heat-shielding coating material can be produced by a known method.

[0030] [Coated Article] A coated article in a first embodiment is a coated article having a substrate and a heat-shielding film having a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less, and containing (i) particles and (ii) a resin component. In the heat-shielding film, either or both of the particles and the resin component have a refractive index with anomalous dispersion for light with a wavelength of 500 nm or more and 1000 nm or less, and the difference in refractive index between the particles and the resin component for light with a wavelength of 500 nm is smaller than the difference in refractive index between the particles and the resin component for light with a wavelength of 1000 nm.

[0031] The particles and resin components contained in the coated article can be the same as those described in the above [Heat Shielding Film], so a description thereof will be omitted.

[0032] The substrate is not particularly limited as long as it can form the heat-shielding film, and examples thereof include automobiles, containers, window materials, and films.

[0033] The method for producing the coated article is not particularly limited as long as it is capable of applying the heat-shielding coating material to the substrate, and examples thereof include spray coating, roll coating, spin coating, and die coating.

[0034] Second Embodiment A heat shielding film, a coating material, and a coated article according to a second aspect will be described below, although the present invention is not limited to the following embodiment.

[0035] [Heat-shielding film] The heat-shielding film in the second embodiment has a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less, a transmittance of 70% or more for light with a wavelength of 500 nm, and a reflectance of 30% or more for light with a wavelength of 1000 nm, thereby achieving both visible light transmittance and heat-shielding properties.

[0036] The structure of the heat shielding film can be the same as that described for the heat shielding film in the first embodiment, and therefore a description thereof will be omitted.

[0037] [Heat-shielding coating material] The heat-shielding coating material according to the second embodiment is a heat-shielding coating material used to form a heat-shielding film having a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less, a transmittance of 70% or more for light with a wavelength of 500 nm, and a reflectance of 30% or more for light with a wavelength of 1000 nm.

[0038] The configuration and manufacturing method of the heat-shielding coating material can be the same as those described for the heat-shielding coating material in the second embodiment, and therefore a description thereof will be omitted.

[0039] [Coated Article] The coated article in the second embodiment is a coated article having a substrate and a heat-shielding film, wherein the heat-shielding film has a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less, a transmittance of 70% or more for light with a wavelength of 500 nm, and a reflectance of 30% or more for light with a wavelength of 1000 nm.

[0040] The structure and manufacturing method of the coated article can be the same as those described for the coated article in the second embodiment, and therefore a description thereof will be omitted.

[0041] The present invention will be further explained below with reference to examples and comparative examples, but the present invention is not limited to the following examples in any way as long as it does not depart from the gist of the invention. "Parts" and "%" used in relation to component amounts are based on mass unless otherwise specified. The product name "DisperBYK 111" used in Examples 1 to 7 and Comparative Example 1 is a dispersant manufactured by BYK Japan. The polystyrene used in Examples 1 to 5 and Comparative Example 1 is a polystyrene manufactured by Sigma-Aldrich Japan with an average molecular weight of 280,000. The dye-incorporated polystyrene used in Examples 6 and 7 was prepared by the following method. The average particle diameter (volume-based cumulative 50% particle diameter (D ５０ ) was measured using a particle size distribution measuring device (trade name "UPA-EX150", manufactured by Nikkiso) by dynamic light scattering.

[0042] <Method for Producing Dye-Incorporated Polystyrene> Dye-incorporated polystyrene having an azo skeleton unit represented by the following structure was produced according to the following scheme.

[0043]

[0044] First, 100 parts of propylene glycol monomethyl ether was heated to reflux at a liquid temperature of 120 ° C. or higher while purging with nitrogen, and a mixture of 150 parts of styrene, 50 parts of acrylic acid, and 1.0 parts of tert-butyl peroxybenzoate [organic peroxide polymerization initiator, manufactured by NOF Corporation, trade name: Perbutyl Z] was added dropwise over 3 hours. After the dropwise addition was completed, the solution was stirred for 3 hours, and then distilled under atmospheric pressure while raising the temperature to 170 ° C. After the liquid temperature reached 170 ° C., the solvent was removed by distillation under reduced pressure at 1 hPa for 1 hour to obtain a resin solid. The solid was dissolved in tetrahydrofuran, reprecipitated with n-hexane, and the precipitated solid was filtered off to obtain a polymer portion (A).

[0045] Next, 1.98 parts of compound (30) was added to 500 parts of tetrahydrofuran and heated to 80°C to dissolve. After dissolution, the temperature was lowered to 50°C, 3 parts of polymer moiety (A) was added and dissolved, and 1.96 parts of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl) was added and stirred at 50°C for 5 hours. The liquid temperature was then gradually returned to room temperature, and the reaction was completed by stirring overnight. After completion of the reaction, the solution was filtered and concentrated, and purified by reprecipitation with methanol to obtain compound (115), which is a dye-incorporated polystyrene. It was confirmed that this dye-incorporated polystyrene has an anomalous dispersion refractive index for light with a wavelength of 500 nm or more and 1000 nm or less.

[0046] Example 1 Resin components Resin: Polystyrene 5.3 parts Anomalous dispersion material: SY162 3.5 parts Particles: Y ２ O ３ Heat-shielding coating material 1 was obtained by dispersing 11 parts of the powder (average particle size 1000 nm) in a paint shaker together with 1.1 parts of methyl ethyl ketone, an organic solvent, DisperBYK 111, a dispersant, and glass beads having a diameter of 1 mm.

[0047] This heat-shielding coating material 1 was applied to a PET film substrate using a bar coater so that the thickness of the heat-shielding film would be 100 μm, thereby obtaining a coated article 1 having a heat-shielding film.

[0048] (Example 2) Resin components Resin: Polystyrene 5.3 parts Anomalous dispersion material: SY162 3.5 parts Particles: Y ２ O ３ Heat-shielding coating material 2 was obtained by dispersing 11 parts of the powder (average particle size 200 nm) together with methyl ethyl ketone as an organic solvent, 1.1 parts of DisperBYK 111 as a dispersant, and glass beads having a diameter of 1 mm using a paint shaker.

[0049] This heat-shielding coating material 2 was applied to a PET film substrate using a bar coater so that the thickness of the heat-shielding film would be 100 μm, thereby obtaining a coated article 2 having a heat-shielding film.

[0050] (Example 3) Resin components Resin: 1.2 parts of polystyrene Anomalous dispersion material: 7.9 parts of iron oxide (average particle diameter 80 nm) Particles: 0.87 parts of diamond (average particle diameter 1000 nm) These were dispersed in a paint shaker together with methyl ethyl ketone as an organic solvent, 1.1 parts of DisperBYK 111 as a dispersant, and glass beads with a diameter of 1 mm, to obtain heat-shielding coating material 3.

[0051] This heat-shielding coating material 3 was applied to a PET film substrate using a bar coater so that the thickness of the heat-shielding film would be 100 μm, thereby obtaining a coated article 3 having a heat-shielding film.

[0052] (Example 4) Resin components Resin: 1.2 parts of polystyrene Anomalous dispersion material: 7.9 parts of iron oxide (average particle diameter 120 nm) Particles: 0.87 parts of diamond (average particle diameter 1000 nm) These were dispersed in a paint shaker together with methyl ethyl ketone as an organic solvent, 1.1 parts of DisperBYK 111 as a dispersant, and glass beads with a diameter of 1 mm, to obtain heat-shielding coating material 4.

[0053] This heat-shielding coating material 4 was applied to a PET film substrate using a bar coater so that the thickness of the heat-shielding film would be 100 μm, thereby obtaining a coated article 4 having a heat-shielding film.

[0054] (Example 5) Resin components Resin: 1.2 parts of polystyrene Anomalous dispersion material: 7.9 parts of iron oxide (average particle diameter 80 nm) Particles: 0.87 parts of diamond (average particle diameter 200 nm) These were dispersed in a paint shaker together with methyl ethyl ketone as an organic solvent, 1.1 parts of DisperBYK 111 as a dispersant, and glass beads with a diameter of 1 mm, to obtain heat-shielding coating material 5.

[0055] This heat-shielding coating material 5 was applied to a PET film substrate using a bar coater so that the thickness of the heat-shielding film would be 100 μm, thereby obtaining a coated article 5 having a heat-shielding film.

[0056] (Example 6) Resin components Resin: dye-incorporated polystyrene 8.8 parts Particles: Y ２ O ３Heat-shielding coating material 6 was obtained by dispersing 11 parts of the powder (average particle size 1000 nm) together with methyl ethyl ketone as an organic solvent, 1.1 parts of DisperBYK 111 as a dispersant, and glass beads having a diameter of 1 mm using a paint shaker.

[0057] This heat-shielding paint 6 was applied to a PET film substrate using a bar coater so that the thickness of the heat-shielding film would be 100 μm, thereby obtaining a coated article 6 having a heat-shielding film.

[0058] (Example 7) Resin components Resin: dye-incorporated polystyrene 8.8 parts Particles: Y ２ O ３ Heat-shielding coating material 7 was obtained by dispersing 11 parts of the powder (average particle size 200 nm) together with methyl ethyl ketone as an organic solvent, 1.1 parts of DisperBYK 111 as a dispersant, and glass beads having a diameter of 1 mm using a paint shaker.

[0059] This heat-shielding coating material 7 was applied to a PET film substrate using a bar coater so that the thickness of the heat-shielding film would be 100 μm, thereby obtaining a coated product 7 having a heat-shielding film.

[0060] Comparative Example 1 A heat-shielding coating material 8 was obtained in the same manner as in Example 1, except that the anomalous dispersion material SY162 was not used.

[0061] This heat-shielding paint 8 was applied to a PET film substrate using a bar coater so that the thickness of the heat-shielding film would be 100 μm, thereby obtaining a coated article 8 having a heat-shielding film.

[0062] The difference in refractive index between the particles and resin component used in heat-shielding coatings 1 to 7 for light with a wavelength of 500 nm was all between 0 and 0.10, and the difference in refractive index for light with a wavelength of 1000 nm was all 0.20 or more. On the other hand, the difference in refractive index between the particles and resin component used in heat-shielding coating 8 for light with a wavelength of 500 nm was higher than 0.10, and the difference in refractive index for light with a wavelength of 1000 nm was 0.20 or more.

[0063] Furthermore, the resin components used in heat-shielding coatings 1 to 7, which have an anomalous dispersion refractive index for light with a wavelength of 500 nm or more and 1000 nm or less, had a refractive index of 1.60 or more and 2.10 or less for light with a wavelength of 500 nm, and a refractive index of 1.50 or more and 1.70 or less for light with a wavelength of 1000 nm. On the other hand, neither the particles nor the resin component used in heat-shielding coating 8 had an anomalous dispersion refractive index.

[0064] Furthermore, the particles used in the heat-shielding coating materials 1 to 8 had a refractive index of 1.60 or more and 2.00 or less for light with a wavelength of 500 nm.

[0065] <Evaluation> For the obtained coated objects 1 to 8, the transmittance for light with a wavelength of 500 nm and the reflectance for light with a wavelength of 1000 nm were measured using a spectrophotometer, and the evaluation was performed according to the following criteria: (Transmittance for light with a wavelength of 500 nm) A: Transmittance is 80% or more and 100% or less B: Transmittance is 70% or more and less than 80% C: Transmittance is 0% or more and less than 70% (Reflectance for light with a wavelength of 1000 nm) A: Reflectance is 50% or more and 100% or less B: Reflectance is 30% or more and less than 50% C: Reflectance is 0% or more and less than 30%

[0066]

[0067] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0068] This application claims priority based on Japanese Patent Application No. 2023-162683 filed on September 26, 2023 and Japanese Patent Application No. 2024-160827 filed on September 18, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A heat-shielding film having a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less, comprising: (i) particles; and (ii) a resin component, wherein either or both of the particles and the resin component have a refractive index with anomalous dispersion for light with a wavelength of 500 nm or more and 1000 nm or less, and the difference in refractive index between the particles and the resin component for light with a wavelength of 500 nm is smaller than the difference in refractive index between the particles and the resin component for light with a wavelength of 1000 nm.

2. A heat-shielding film as described in claim 1, wherein the difference in refractive index between the particles and the resin component for light with a wavelength of 500 nm is 0 or more and 0.10 or less, and the difference in refractive index between the particles and the resin component for light with a wavelength of 1000 nm is 0.20 or more.

3. A heat shielding film according to claim 1 or 2, wherein the average particle size of the particles is 0.3 μm or more and 5.0 μm or less.

4. A heat shielding film according to any one of claims 1 to 3, having a thickness of 1 µm or more.

5. A heat shielding film according to any one of claims 1 to 4, wherein the transmittance of light having a wavelength of 300 nm or more and 800 nm or less is 70% or more.

6. A heat shielding film according to any one of claims 1 to 5, wherein the particles have a refractive index with anomalous dispersion for light having a wavelength of 500 nm or more and 1000 nm or less.

7. A heat shielding film according to any one of claims 1 to 6, wherein the resin component contains a resin having a refractive index with anomalous dispersion for light having a wavelength of 500 nm or more and 1000 nm or less.

8. The heat shielding film according to claim 7, wherein the resin having an anomalous dispersion refractive index for light with a wavelength of 500 nm or more and 1000 nm or less has a peak in a wavelength region of 300 nm or more and 500 nm or less in a spectral absorption spectrum.

9. A heat shielding film according to any one of claims 1 to 8, wherein the resin component contains a resin and an anomalous dispersion material having an anomalous dispersion refractive index for light having a wavelength of 500 nm or more and 1000 nm or less.

10. A heat-shielding film according to any one of claims 1 to 9, wherein the particles or resin component having a refractive index with anomalous dispersion for light with a wavelength of 500 nm or more and 1000 nm or less has a refractive index for light with a wavelength of 500 nm or more of 1.60 or more and 2.10 or less, and a refractive index for light with a wavelength of 1000 nm or less of 1.50 or more and 1.70 or less.

11. A heat shielding film according to any one of claims 1 to 10, wherein the particles have a refractive index of 1.60 or more and 2.00 or less for light with a wavelength of 500 nm.

12. A heat-shielding paint used to form a heat-shielding film having a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less, comprising: (i) particles; (ii) a resin component; and (iii) an organic solvent; one or both of the particles and the resin component have a refractive index with anomalous dispersion for light with a wavelength of 500 nm or more and 1000 nm or less; and the difference in refractive index between the particles and the resin component for light with a wavelength of 500 nm is smaller than the difference in refractive index between the particles and the resin component for light with a wavelength of 1000 nm.

13. A coated article having a substrate and a heat shielding film having a transmittance of 50% or more for light having a wavelength of 300 nm or more and 800 nm or less, the coated article comprising: (i) particles; and (ii) a resin component, the heat shielding film being characterized in that either one or both of the particles and the resin component have an anomalous dispersion refractive index for light having a wavelength of 500 nm or more and 1000 nm or less, and the difference in refractive index between the particles and the resin component for light having a wavelength of 500 nm is smaller than the difference in refractive index between the particles and the resin component for light having a wavelength of 1000 nm.

14. A heat-shielding film having a transmittance of 50% or more for light with a wavelength of 300 nm or more and 800 nm or less, a transmittance of 70% or more for light with a wavelength of 500 nm, and a reflectance of 30% or more for light with a wavelength of 1000 nm.

15. A heat-shielding paint used to form a heat-shielding film having a light transmittance of 50% or more for wavelengths of 300 nm or more and 800 nm or less, a light transmittance of 70% or more for a wavelength of 500 nm, and a light reflectance of 30% or more for a wavelength of 1000 nm.

16. A coated article having a substrate and a heat-shielding film, wherein the heat-shielding film has a light transmittance of 50% or more for a wavelength of 300 nm or more and 800 nm or less, a light transmittance of 70% or more for a wavelength of 500 nm, and a light reflectance of 30% or more for a wavelength of 1000 nm.

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