JP6747450B2 - Thermochromic film and thermochromic composite - Google Patents

Description

The present invention relates to a thermochromic film and a thermochromic composite, and more particularly to a thermochromic film exhibiting durability and haze stability.

In recent years, in order to reduce the heat felt on the human skin due to the influence of sunlight entering from a car window, a laminated glass having high heat insulating properties or heat shielding properties is on the market. Recently, with the spread of electric vehicles and the like, a near-infrared light (heat ray) shielding film applied to laminated glass has been actively developed from the viewpoint of increasing the cooling efficiency in the vehicle.

By applying the near-infrared light shielding film to a window glass of a vehicle body or a building, it is possible to reduce the load on the cooling equipment such as an air conditioner in the vehicle, and it is an effective means for energy saving.
As such a near infrared light shielding film, an optical film containing a conductor such as ITO (indium tin oxide) as an infrared absorbing substance is disclosed.
For example, Patent Document 1 discloses a near infrared light shielding film including a functional plastic film having an infrared reflection layer and an infrared absorption layer. Further, Patent Document 2 has a reflective layer laminate in which a large number of low-refractive index layers and high-refractive index layers are alternately laminated, and the near-infrared light is adjusted by adjusting the layer thickness of each refractive index layer. A near-infrared light shielding film that selectively reflects is proposed.

Due to its high near-infrared light shielding effect, the near-infrared light shielding film having such a configuration is preferably used in a low latitude region near the equator where the illuminance of sunlight is high. On the other hand, in the mid-latitude to high-latitude regions in winter, on the contrary, there is a case where it is desired to take in sunlight as much as possible into the vehicle or indoors. A method of applying a thermochromic material controlled by the above has been studied. As a typical material thereof, vanadium dioxide (hereinafter, also referred to as “VO ₂ ”) can be given. VO ₂ is known to undergo a phase transition in the temperature range of about 50 to 60° C. and exhibit thermochromic properties.

On the other hand, when VO ₂ comes into contact with moisture and oxygen in the atmosphere, the crystal structure changes, and the spherical particles change into acicular particles. Therefore, there is a problem that light is scattered in the film, haze is increased, and the visibility of the film is deteriorated.
Patent Document 3 reports that VO ₂ is protected with a silane coupling agent and a long-chain alkyl resin. Further, in Patent Document 4, protection with a polycarboxylic acid is reported, but nothing is reported regarding haze variation of the film.
As another problem, when a film containing VO ₂ is attached to glass via an adhesive, a phenomenon of accelerating the oxidation of VO ₂ occurs, which causes deterioration of the film.

JP, 2010-222233, A International Publication No. 2013/065679 Japanese Patent Publication No. 2015-513508 JP, 2012-25629, A

The present invention has been made in view of the above problems and circumstances, and a problem to be solved is to provide a thermochromic film and a thermochromic composite that achieve both durability and haze stability.

The present inventor, as a result of studies to solve the above problems, by adding a chelate complex to the vanadium dioxide-containing layer (thermochromic layer), the problem of haze caused by the change in particle shape and alkali extracted from glass It was found that the influence of the components can be suppressed.
That is, the said subject of this invention is solved by the following means.

1. A thermochromic film containing vanadium dioxide particles exhibiting thermochromic properties,
Together with the vanadium dioxide particles, have a vanadium dioxide-containing layer containing a chelate complex, and,
Content of the said chelate complex exists in the range of 0.1-20 mass% with respect to the total mass of the said vanadium dioxide containing layer, The thermochromic film characterized by the above-mentioned.

2 . Content of the said chelate complex exists in the range of 1-15 mass% with respect to the total mass of the said vanadium dioxide containing layer, The thermochromic film of Claim 1 characterized by the above-mentioned.

3 . A thermochromic composite, which is a composite in which the thermochromic film according to item 1 or 2 is bonded to glass.

4 . 4. The thermochromic composite according to claim 3, which is a composite in which a thermochromic film having an adhesive layer adjacent to the vanadium dioxide-containing layer is attached to the glass.

By the above means of the present invention, it is possible to provide a thermochromic film and a thermochromic composite that achieve both durability and haze stability.

Although the mechanism of action or mechanism of action of the present invention has not been clarified, it is presumed as follows.
It is considered that the chelate complex forms some interaction with vanadium dioxide by including the chelate complex in the vanadium dioxide-containing layer. This makes it possible to suppress the influence of moisture and oxygen on the vanadium dioxide particles from the outside, and it is speculated that this suppresses the shape change of the vanadium dioxide particles.

Further, as a result of earnest studies by the inventor, regarding the phenomenon of promoting the oxidation of VO ₂ , it was found that the inclusion of the chelate complex in the vanadium dioxide-containing layer can suppress the influence of the alkaline component derived from the glass to be laminated. It was It is considered that this is because the chelate complex captures the alkali component and suppresses the influence on the vanadium dioxide particles.
That is, by adding the chelate complex to the vanadium dioxide-containing layer, it is possible to suppress the shape change and structural change of the vanadium dioxide particles, and as a result, it was possible to produce a highly durable thermochromic film. I'm guessing.

Schematic sectional view of the thermochromic film of the present invention Schematic sectional view of the thermochromic film of the present invention Schematic cross-sectional view of the thermochromic composite of the present invention Schematic cross-sectional views of the thermochromic composites of Comparative Example 2 and Comparative Example 3. Transmission electron micrograph of thermochromic film of comparative example Transmission electron micrograph of thermochromic film of comparative example Transmission electron micrograph of the thermochromic film of the present invention Transmission electron micrograph of the thermochromic film of the present invention

The thermochromic film of the present invention is a thermochromic film containing vanadium dioxide particles exhibiting thermochromic properties, characterized by having a vanadium dioxide-containing layer containing a chelate complex together with the vanadium dioxide particles. This feature is a technical feature common to or corresponding to the inventions according to the claims.

Further, the content of the chelate complex being within the range of 0.1 to 20% by mass with respect to the total mass of the vanadium dioxide-containing layer makes it possible to more effectively prevent the influence of moisture and oxygen from the outside. It is preferable because it can be suppressed.

Further, the content of the chelate complex is preferably within the range of 1 to 15 mass% with respect to the total mass of the vanadium dioxide-containing layer, from the viewpoint of manifesting the effect of the present invention.

Since the thermochromic composite of the present invention is a composite in which the thermochromic film of the present invention is bonded to glass, it is preferable in that it can be applied to various fields for construction and vehicles using glass as a support.

Further, a composite in which a thermochromic film having an adhesive layer adjacent to the vanadium dioxide-containing layer is attached to the glass is preferable from the viewpoint of manifesting the effect of the present invention.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, "-" shown in the following description is used to mean that the numerical values described before and after the "-" are included as a lower limit value and an upper limit value.

<Thermochromic film>
The thermochromic film of the present invention is a thermochromic film containing vanadium dioxide particles exhibiting thermochromic properties, and has a vanadium dioxide-containing layer containing a chelate complex together with the vanadium dioxide particles.
Here, the thermochromic property refers to a property of controlling optical properties of shielding and transmitting near infrared light depending on temperature. The thermochromic property of the vanadium dioxide particles (hereinafter, also simply referred to as “VO ₂ particles”) according to the present invention is particularly preferable if optical characteristics such as light transmittance and light reflectance are reversibly changed due to temperature change. It is not limited. The preferred thermochromic properties of the vanadium dioxide particles according to the present invention include, for example, a difference in light transmittance between 25° C. and 50% RH and 85° C. and 85% RH of 7% or more, and more preferably 10% or more. Furthermore, it is 15% or more.
The light transmittance can be measured as a light transmittance at a wavelength of 1500 nm using, for example, a spectrophotometer V-670 (manufactured by JASCO Corporation).
The vanadium dioxide particles having thermochromic properties of the present invention are contained, and the details of the vanadium dioxide particles, the chelate complex, and other materials used for the thermochromic film will be described.

[Vanadium oxide]
Vanadium dioxide according to the present invention is one aspect of vanadium oxide. Vanadium oxide takes various forms in the natural world, and includes V ₂ O ₅ , H ₃ V ₂ O ₇ ⁻ , H ₂ VO ₄ ⁻ , HVO ₄ ²⁻ , VO ₄ ³⁻ , VO ²⁺ , VO ₂ , V ³⁺ , V. ^Examples thereof include structures such as ₂ O ₃ , V ²⁺ , V ₂ O ₂ and V. The morphology changes depending on the respective environmental atmospheres, and generally V ₂ O ₅ is formed under an acidic environment and V ₂ O ₃ is formed under a reducing environment. Therefore, VO ₂ is relatively easy to oxidize and reduce, and the crystal structure changes depending on the surrounding environment.
Since VO ₂ exhibiting thermochromic property (automatic dimming property) is expressed in a monoclinic crystal structure, VO ₂ used in the present invention is a monoclinic crystal.

[Vanadium dioxide particles]
As the crystal form of the vanadium dioxide particles according to the present invention, it is preferable to use rutile type VO ₂ particles (hereinafter, also simply referred to as VO ₂ particles) from the viewpoint of efficiently expressing thermochromic properties.
The rutile-type VO ₂ particles have a monoclinic structure at a transition temperature or lower, and are therefore referred to as M-type. The vanadium dioxide particles according to the present invention may contain other compounds such as VO ₂ particles of other crystal type such as A-type or B-type, organic compounds, other metal oxides, etc. within a range that does not impair the purpose. Good.

In addition, the VO ₂ particles according to the present invention are present in a vanadium dioxide-containing layer (hereinafter, also referred to as a thermochromic layer) in a state where the number average particle diameter of primary particles and secondary particles is less than 500 nm. Is preferred.
Although various measuring methods can be applied to the method for measuring the particle diameter, it is preferable to measure according to the dynamic light scattering method.
The preferred number average particle size of the primary particles and secondary particles in the VO ₂ particles according to the present invention is less than 500 nm, more preferably within the range of 1 to ₂₀₀ nm, and more preferably within the range of 5 to 100 nm. And most preferably within the range of 5 to 60 nm.

The aspect ratio of the VO ₂ particles is preferably in the range of 1.0 to 3.0.
The VO ₂ particles having such characteristics have a sufficiently small aspect ratio and an isotropic shape, and therefore have good dispersibility when added to a solution. In addition, since the particle size of the single crystal is sufficiently small, it is possible to exhibit better thermochromic properties than conventional particles.

In addition to VO ₂ , the VO ₂ particles according to the present invention include, for example, tungsten (W), molybdenum (Mo), niobium (Nb), tantalum (Ta), tin (Sn), rhenium (Re), iridium (Ir). ), osmium (Os), ruthenium (Ru), germanium (Ge), chromium (Cr), iron (Fe), gallium (Ga), aluminum (Al), fluorine (F) and phosphorus (P). It may include at least one selected element.
By adding such an element, it becomes possible to control the phase transition characteristics (in particular, dimming temperature) of the vanadium dioxide particles. The total amount of such additives with respect to the finally obtained vanadium dioxide particles is about 0.1 to 5.0 atom% with respect to vanadium (V) atoms.

(1: Method for producing aqueous dispersion of vanadium dioxide particles)
Generally, a method for synthesizing vanadium dioxide particles includes a method of pulverizing a VO ₂ sintered body synthesized by a solid phase method and a method of synthesizing VO _{2 in} a liquid phase using vanadium pentoxide (V ₂ O ₅ ) as a raw material. A water-based synthetic method for growing particles can be mentioned.
In the present invention, VO ₂ produced by any method can be applied. A dispersant is added to VO ₂ produced by either method to prepare a dispersion in an aqueous system or a solvent system.

The amount of the dispersant added is preferably within the range of 0.1 to 1.0% by mass.
In the case of a water-based dispersant, in addition to low molecular weight dispersants such as alkyl sulfonates, alkylbenzene sulfonates, diethylamine, ethylenediamine, and quaternary ammonium salts, polyoxyethylene nonylphenyl ether, polyexyethylene lauryl Examples thereof include acid ether, hydroxyethyl cellulose, polyvinylpyrrolidone, polyethylene glycol, and silane coupling agents. Particularly, polyvinylpyrrolidone or cellulose resin is preferable, and it can be used in combination with the chelate complex in the present invention.

As the organic solvent-based dispersant, generally used organic-based dispersants such as alkylamines, silane coupling agents, and phosphoric acid can be used.
Then, by using these dispersants, a coating liquid for forming a thermochromic layer can be prepared as described below without drying the VO ₂ particles in the dispersion liquid.
By forming a thermochromic layer using the coating liquid for forming a thermochromic layer in this state, the VO ₂ particles having a preferable number average particle diameter of which the number average particle diameter of primary particles and secondary particles is less than 150 nm are contained. A thermochromic layer can be formed.

In addition, as a method for producing VO ₂ particles, if necessary, fine particles of TiO ₂ or the like, which become nuclei for grain growth, are added as nuclei particles, and the nuclei particles are grown to produce VO ₂ particles. Can also
When using a water-soluble binder resin as the binder resin, after prepared as an aqueous dispersion containing the aforementioned VO ₂ particles, without drying the VO ₂ particles of the aqueous dispersion, VO ₂ particles separated It is preferable to prepare a coating liquid for forming a thermochromic layer by mixing it with a water-soluble binder resin solution in a dispersed state.

Next, the details of the method for producing VO ₂ particles by the hydrothermal method suitable for the present invention will be further described.
The production process of VO ₂ particles by a typical hydrothermal method is shown below.
(Process 1)
A substance (I) containing vanadium (V), hydrazine (N ₂ H ₄ ) or a hydrate thereof (N ₂ H ₄ ·nH ₂ O), and water are mixed to prepare a solution (A). The solution (A) may be an aqueous solution in which the substance (I) is dissolved in water, or may be a suspension in which the substance (I) is dispersed in water.

Examples of the substance (I) include divanadium pentoxide (V ₂ O ₅ ), ammonium vanadate (NH ₄ VO ₃ ), vanadium trichloride oxide (VOCl ₃ ), sodium metavanadate (NaVO ₃ ), and the like. .. The substance (I) is not particularly limited as long as it is a compound containing pentavalent vanadium (V). Hydrazine (N ₂ H ₄ ) and its hydrate (N ₂ H ₄ ·nH ₂ O) function as a reducing agent for substance (I) and have the property of being easily dissolved in water.

The solution (A) may further contain a substance (II) containing the element to be added in order to add the element to the finally obtained single crystal particles of vanadium dioxide (VO ₂ ). Examples of the element to be added include tungsten (W), molybdenum (Mo), niobium (Nb), tantalum (Ta), tin (Sn), rhenium (Re), iridium (Ir), osmium (Os), ruthenium ( Ru), germanium (Ge), chromium (Cr), iron (Fe), gallium (Ga), aluminum (Al), fluorine (F) or phosphorus (P).
By adding these elements to the finally obtained vanadium dioxide (VO ₂ ) single crystal particles, the thermochromic property of the vanadium dioxide particles, particularly the transition temperature, can be controlled.

Further, this solution (A) may further contain a substance (III) having an oxidizing or reducing property. Examples of the substance (III) include hydrogen peroxide (H ₂ O ₂ ). By adding the substance (III) having an oxidizing or reducing property, the pH of the solution can be adjusted and the substance containing vanadium (V) which is the substance (I) can be uniformly dissolved.

(Process 2)
Next, hydrothermal reaction treatment is performed using the prepared solution (A). Here, the “hydrothermal reaction” means a chemical reaction that occurs in hot water (subcritical water) whose temperature and pressure are lower than the critical point (374° C., 22 MPa) of water. The hydrothermal reaction treatment is performed, for example, in an autoclave device. By the hydrothermal reaction treatment, single crystal particles containing vanadium dioxide (VO ₂ ) are obtained.

The conditions of the hydrothermal reaction treatment (for example, the amount of the reaction product, the treatment temperature, the treatment pressure, the treatment time, etc.) are appropriately set, but the temperature of the hydrothermal reaction treatment is, for example, in the range of 250 to 350°C. And preferably in the range of 250 to 300°C, and more preferably in the range of 250 to 280°C. By lowering the temperature, the particle size of the obtained single crystal particles can be reduced, but if the particle size is excessively small, the crystallinity will decrease. The hydrothermal reaction treatment time is preferably, for example, in the range of 1 hour to 5 days. By increasing the time, it is possible to control the particle size and the like of the obtained single crystal particles, but if the treatment time is excessively long, the energy consumption increases.

(Process 3)
If necessary, the surface of the obtained vanadium dioxide particles may be coated with a resin or surface-modified. Thereby, the surface of the vanadium dioxide particles is protected and the surface-modified single crystal particles can be obtained. In the present invention, it is a preferred embodiment that the surface of the vanadium dioxide particles is covered with the binder resin of the present invention having a glass transition temperature of 65° C. or lower.

The "coating" in the present invention may be a state in which the entire surface of the vanadium dioxide particles is completely covered with the resin, or a part of the particle surface is covered with the resin. It may be in a state. Preferably, 50% or more of the total area of the particle surface is covered, and 80% or more is more preferably covered.
Through the above steps 1 to 3, a dispersion liquid containing VO ₂ -containing single crystal particles having thermochromic properties can be obtained.

[Method of crushing VO ₂ ]
There are various methods for making VO ₂ into fine particles, but there are various methods such as bead mill, ultrasonic crushing, and high-pressure homogenizer, and any method can be used to produce VO ₂ particles.
Although various beads can be used in the bead mill, it is preferable to use zirconia beads from the viewpoint of hardness and price.

<Treatment of impurities in vanadium dioxide particles aqueous dispersion>
The dispersion liquid of the vanadium dioxide particles prepared by the above-mentioned water-based synthesis method contains impurities such as residues generated in the synthesis process, and when the thermochromic layer is formed, it causes the generation of secondary aggregated particles. However, it may cause deterioration of the thermochromic layer during long-term storage, and it is preferable to remove impurities at the stage of dispersion.

As a method for removing impurities in the vanadium dioxide particle aqueous dispersion liquid, a conventionally known means for separating foreign substances and impurities can be applied. For example, the VO ₂ particle aqueous dispersion liquid is subjected to centrifugation to obtain vanadium dioxide particles. The method of precipitating and removing the impurities in the supernatant, and then adding and dispersing the dispersion medium again, or the method of removing the impurities out of the system by using an exchange membrane such as an ultrafiltration membrane may be used. From the viewpoint of preventing aggregation of particles, the method using an ultrafiltration membrane is most preferable.
Examples of the material of the ultrafiltration membrane include cellulose type, polyether sulfone type, polytetrafluoroethylene (abbreviation: PTFE) and the like. Among them, polyether sulfone type and PTFE are preferably used.

[Chelate complex]
The chelate complex according to the present invention refers to a metal complex in which at least one ligand having a plurality of coordination sites is coordinate-bonded to a metal ion.
Here, the metal complex is a compound having a metal atom in the molecular structure and having a ligand bonded to the metal atom by a coordinate bond.
It is believed that the chelate complex forms some interaction with vanadium dioxide by adding the chelate complex to the vanadium dioxide-containing layer. This makes it possible to suppress the influence of moisture and oxygen on the vanadium dioxide particles from the outside, and it is speculated that this suppresses the shape change of the vanadium dioxide particles.

As the central metal used in the chelate complex according to the present invention, titanium, aluminum and zinc are particularly preferable.
Examples of the chelate ligand are EDTA (ethylenediaminetetraacetic acid), EDA (ethylenediamine), BAPTA (1,2-bis(o-aminophenoxide)ethane-N,N,N',N'-tetraacetic acid) and crown ether. (12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6, diaza-18-crown-6) and the like can be used, but the invention is not limited thereto. ..
Examples of the structure are preferably aluminum trisacetylacetonate, diisopropoxybis(acetylacetonato)titanium, zirconium tetraacetylacetonate, etc., but are not limited thereto.

As the chelate complex, a commercially available product may be used, such as titanium dipropoxydiacetylacetonate (Matsumoto Fine Chemical Co., Ltd., Organix TC-100: trade name), titanium triethanolaminate (Matsumoto Fine Chemical KK, Organix). TC-400: trade name), titanium dioctoxy dioctylene glycolate (Matsumoto Fine Chemical Co., Ltd., Organix TC-200: trade name), titanium diporopoxy diethyl acetate (Matsumoto Fine Chemical Co., Ltd., Organix TC- 750: trade name), titanium 2-(2-aminoethylamino) ethoxide (Matsumoto Fine Chemical Co., Ltd., Organix TC-510: trade name), hydroxyzirconium tris (ammonium lactate) (Matsumoto Fine Chemical Co., Ltd., Organix ZC-300: trade name) Zirconium monoacetylacetonate (Matsumoto Fine Chemical Co., Ltd., Organix ZC-540: trade name) and the like are commercially available products.

The content of the chelate complex is preferably in the range of 0.1 to 20 mass% and more preferably in the range of 1 to 15 mass% with respect to the total mass of the vanadium dioxide-containing layer.
It is considered that the inclusion of the chelate complex within the above range makes it possible to suppress the influence of moisture and oxygen from the outside and obtain a thermochromic film exhibiting excellent thermochromic properties.

[Outline of layer structure of thermochromic film]
A typical configuration example of the thermochromic film of the present invention will be described with reference to the drawings.
One of the preferable embodiments of the thermochromic film of the present invention is a structure in which a vanadium dioxide-containing layer (thermochromic layer) is formed on a transparent substrate.
FIG. 1 is a schematic cross-sectional view showing an example of the basic configuration of a thermochromic film having a thermochromic layer containing vanadium dioxide particles and a binder resin defined in the present invention.

The thermochromic film 1 shown in FIG. 1 has a structure in which a thermochromic layer 3 is laminated on a transparent substrate 2. The thermochromic layer 3 exists in a state where vanadium dioxide particles are dispersed in the binder resin B1 contained in the thermochromic layer. This is vanadium dioxide particles, constitute the primary particles VO _S of vanadium dioxide vanadium dioxide particles are present independently, an aggregate of two or more vanadium dioxide particles (also called aggregates), VO _There are 2 secondary particles VO _M. In the present invention, an aggregate of two or more vanadium dioxide particles is collectively referred to as a secondary particle, and is also referred to as a secondary particle aggregate or a secondary aggregate particle.

In the present invention, the number average particle diameter of all particles of the primary particles VO _S and secondary particles VO _M of the VO ₂ particles in the thermochromic layer 3 is preferably less than 150 nm.
The number average particle diameter of the VO ₂ particles in the thermochromic layer can be determined by the following method.
Another preferred embodiment of the thermochromic film of the present invention is a hybrid structure in which the thermochromic layer also serves as a transparent substrate.

FIG. 2 is a schematic cross-sectional view showing another example of the basic constitution of the thermochromic film of the present invention, in which the transparent substrate 2 and the thermochromic layer 3 shown in FIG. 1 are constituted by the same layer. thermochromic consists of a electrochromic layer (2 + 3), as a resin constituting the transparent substrate, thermochromic using a binder resin B2 contained in the electrochromic layer, in the binder resin B2, VO ₂ particles the VO ₂ a primary particle VO _S of, being the secondary particles VO _M of vanadium dioxide particles dispersed, is formed to have constituted a thermochromic layer having both a transparent substrate in a single layer.

The thermochromic film of the present invention may have, in addition to the thermochromic layer, a near infrared light shielding layer 4 having a function of shielding at least a part of light within a wavelength range of 700 to 1000 nm.
As the optical characteristics of the thermochromic film of the present invention, the visible light transmittance measured according to JIS R3106-1998 is preferably 60% or more, more preferably 70% or more, and further preferably 80% or more. is there. Further, it is preferable to have a region having a reflectance of more than 50% in a region of wavelength 900 to 1400 nm.

<<Each constituent material of thermochromic film>>
The details of the thermochromic layer, which is a component of the thermochromic film of the present invention, the transparent substrate provided as necessary, and the near-infrared light shielding layer will be described below.

[Thermochromic layer]
The thermochromic layer used in the present invention preferably contains at least VO ₂ particles and a resin binder. Examples of the binder resin applicable to the present invention include a water-soluble binder resin and a solvent-based binder, and are not particularly limited, but among them, a water-soluble binder resin is preferable.

(Water-soluble binder resin)
As described above, in the thermochromic layer used in the present invention, a water-soluble binder resin can also be used as the binder resin.
The water-soluble binder resin mentioned here is a resin that dissolves or disperses 1.0 g or more in 100 g of water at 25°C. Further, a resin which is also dissolved at 25° C. after being dissolved in hot water is also defined as the water-soluble binder resin in the present invention.

As the water-soluble binder resin useful for forming the thermochromic layer, for example, gelatins, graft polymers of gelatin and other polymers, albumin, proteins such as casein, celluloses, sodium alginate, cellulose sulfate, dextrin, Dextran, sugar derivatives such as dextran sulfate, naturally derived materials such as thickening polysaccharides, polyvinyl alcohols, polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymers, potassium acrylate-acrylonitrile copolyesters Acrylic resin such as polymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic Styrene acrylic acid resin such as acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, or styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer, styrene-sodium styrenesulfonate copolymer Polymer, styrene-2-hydroxyethyl acrylate copolymer, styrene-2-hydroxyethyl acrylate-potassium styrenesulfonate copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinylnaphthalene- Acrylic acid copolymers, vinyl naphthalene-maleic acid copolymers, vinyl acetate-maleic acid ester copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-acrylic acid copolymers and other vinyl acetate-based copolymers And salts thereof.

Among them, a polymer containing a repeating unit component having a hydroxy group in an amount of 50 mol% or more, which has a high affinity with VO ₂ particles and has a high effect of preventing the particles from aggregating even when the film is dried, is preferable. Examples thereof include celluloses, polyvinyl alcohols, and acrylic resins having a hydroxy group. Among them, polyvinyl alcohols and celluloses are most preferably used.

As usable crosslinking agents for obtaining water resistance of the resin binder, isocyanate compounds, melamine compounds, glyoxal compounds, oxazoline compounds, aziridine, titanium chelate, urea formalin resin, glutaraldehyde, tannic acid, carbodiimide compounds Etc. can be used. The addition concentration is preferably within the range of 1 to 50 mass% with respect to the resin.
Also, an aqueous emulsion can be added to improve the water resistance. Preferred examples include acrylic resin emulsions and urethane resin emulsions.

(Other additives for thermochromic layer)
Listed below are various additives that can be applied to the thermochromic layer used in the present invention within a range that does not impair the intended effects of the present invention. For example, the ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, JP-A-57-74192, and JP-A-57-74 No. 879889, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091, and JP-A-3-13376. Various cationic or nonionic surfactants, JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, and JP-A-4-24271. Fluorescent whitening agents, sulfuric acid, phosphoric acid, acetic acid, citric acid, pH adjusting agents such as sodium hydroxide, potassium hydroxide and potassium carbonate, antifoaming agents, lubricants such as diethylene glycol, etc. Preservatives, fungicides, antistatic agents, matting agents, heat stabilizers, antioxidants, flame retardants, crystal nucleating agents, inorganic particles, organic particles, viscosity reducing agents, lubricants, infrared absorbers, dyes, pigments, etc. Various known additives may be used.

(Method of forming thermochromic layer)
The wet coating method used for forming the thermochromic layer is not particularly limited, and examples thereof include roll coating method, rod bar coating method, air knife coating method, spray coating method, slide type curtain coating method, and US Pat. No. 2,761,419. The specification includes the slide hopper coating method and the extrusion coating method described in US Pat. No. 2,761,791.

[Transparent substrate]
The transparent base material applicable to the present invention is not particularly limited as long as it is transparent, and examples thereof include glass, quartz, and a transparent resin film. However, flexibility and production suitability (manufacturing process suitability) From the viewpoint, it is preferably a transparent resin film. The term "transparent" as used in the present invention means that the average light transmittance in the visible light region is 50% or more, preferably 60% or more, more preferably 70% or more, and particularly preferably 80% or more.

The thickness of the transparent substrate is preferably within the range of 30 to 200 μm, more preferably within the range of 30 to 100 μm, and further preferably within the range of 35 to 70 μm. If the thickness of the transparent substrate is 30 μm or more, wrinkles and the like are less likely to occur during handling, and if the thickness is 200 μm or less, for example, in the case of producing a laminated glass, when it is bonded to a glass substrate. Improves the ability to follow curved glass surfaces.

The transparent substrate is preferably a biaxially oriented polyester film, but it is also possible to use an unstretched or at least one stretched polyester film. A stretched film is preferable from the viewpoint of improving strength and suppressing thermal expansion. In particular, when the laminated glass provided with the thermochromic film of the present invention is used as an automobile windshield, a stretched film is more preferable.
The transparent substrate preferably has a heat shrinkage ratio of 0.1 to 3.0% at a temperature of 150° C. from the viewpoint of preventing wrinkles of the thermochromic film and cracking of the infrared reflective layer. It is more preferably in the range of 1.5 to 3.0%, further preferably in the range of 1.9 to 2.7%.

The transparent substrate applicable to the thermochromic film of the present invention is not particularly limited as long as it is transparent, but it is preferable to use various resin films, for example, a polyolefin film (for example, polyethylene, polypropylene, etc.). ), a polyester film (for example, polyethylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride, a triacetyl cellulose film and the like can be used, and a polyester film and a triacetyl cellulose film are preferable.

The polyester film (hereinafter, simply referred to as polyester) is not particularly limited, but a polyester having a film-forming property containing a dicarboxylic acid component and a diol component as main constituents is preferable. The main constituent dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylethane dicarboxylic acid, Examples thereof include cyclohexane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl thioether dicarboxylic acid, diphenyl ketone dicarboxylic acid, phenylindane dicarboxylic acid and the like. As the diol component, ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyethoxyphenyl)propane, bis( 4-hydroxyphenyl)sulfone, bisphenol full orange hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like can be mentioned. Among the polyesters containing these as the main constituents, terephthalic acid or 2,6-naphthalenedicarboxylic acid as a dicarboxylic acid component and ethylene glycol or 1 as a diol component from the viewpoints of transparency, mechanical strength, dimensional stability and the like. Polyesters containing 4,4-cyclohexanedimethanol as a main constituent are preferred. Among them, polyesters containing polyethylene terephthalate or polyethylene naphthalate as a main constituent, copolymerized polyesters containing terephthalic acid, 2,6-naphthalenedicarboxylic acid and ethylene glycol, and mixtures of two or more of these polyesters Polyester as a constituent is preferable.

When a transparent resin film is used as the transparent substrate, particles may be contained within a range that does not impair transparency in order to facilitate handling. Examples of particles used in the present invention include inorganic particles such as calcium carbonate, calcium phosphate, silica, kaolin, talc, titanium dioxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite and molybdenum sulfide, and crosslinked polymers. Examples thereof include particles and organic particles such as calcium oxalate. Examples of the method of adding particles include a method of adding particles by adding them to a polyester as a raw material, a method of directly adding to an extruder, etc. Even if either one of them is adopted. Well, the two methods may be used together. In the present invention, additives may be added in addition to the above particles, if necessary. Examples of such additives include stabilizers, lubricants, cross-linking agents, anti-blocking agents, antioxidants, dyes, pigments, and ultraviolet absorbers.

Further, the transparent resin film may be subjected to a relaxation treatment and an off-line heat treatment in terms of dimensional stability. The relaxation treatment is preferably performed in the step of heat setting during the stretching and film forming step of the polyester film, and then in the step of transversely stretching the tenter, or in the step of winding after exiting the tenter. The relaxation treatment is preferably performed at a treatment temperature in the range of 80 to 200°C, more preferably in the range of 100 to 180°C. Further, it is preferable that the relaxation rate is in the range of 0.1 to 10% in both the longitudinal direction and the width direction, and more preferably the relaxation rate is in the range of 2 to 6%. By subjecting the relaxed base material to the off-line heat treatment, the heat resistance is improved and the dimensional stability is improved.
The transparent resin film is preferably coated inline with the undercoat layer coating liquid on one or both surfaces during the film formation process. In the present invention, the undercoat coating in the film forming process is called in-line undercoating.

[Near infrared light shielding layer]
In the thermochromic film of the present invention, in addition to the thermochromic layer, a near infrared light shielding layer having a function of shielding at least a part of the light wavelength range of 700 to 1000 nm may be provided. ..
Details of the near-infrared light shielding layer applicable to the present invention are, for example, JP 2012-131130 A, JP 2012-139948 A, JP 2012-185342 A, JP 2013-080178 A. It is possible to refer to the constituent elements and the forming method described in JP-A-2014-089347 and the like.

<Thermochromic complex>
The thermochromic film of the present invention can be used as a thermochromic composite 6 including a thermochromic film as a constituent element. Specifically, the thermochromic composite 6 of the present invention is formed by adhering the thermochromic film 1 of the present invention to the glass member 5 (see FIGS. 3 and 4) or by sandwiching the thermochromic film 1 of the present invention between a pair of glass members. It is also preferred to compose glass. Although not shown, it is also preferable that the thermochromic film composite of the present invention has an adhesive layer adjacent to the vanadium dioxide-containing layer.
As shown in FIGS. 3 and 4, the arrangement of the thermochromic layers forming the thermochromic film may be the arrangement sandwiched between the transparent substrate and the glass (see FIG. 3), but the arrangement not sandwiched ( (See FIG. 4), but the arrangement sandwiched between the transparent substrate and the glass shown in FIG. 3 is less susceptible to external influences and the chelate complex contained in the thermochromic layer is It is considered that haze can be improved by suppressing the influence of the alkaline component derived from glass.
In the case of laminated glass, it can be used for automobiles, railway vehicles, aircraft, ships, buildings and the like. Laminated glass can be used for other purposes. The laminated glass is preferably laminated glass for buildings or vehicles. The laminated glass can be used as a windshield, side glass, rear glass or roof glass of an automobile.

[Glass]
Examples of the glass member include inorganic glass and organic glass (resin glazing). Examples of the inorganic glass include float plate glass, heat ray absorbing plate glass, polished plate glass, template glass, mesh plate glass, wire plate glass, and colored glass such as green glass. The organic glass is synthetic resin glass that substitutes for inorganic glass. Examples of the organic glass (resin glazing) include a polycarbonate plate and a poly(meth)acrylic resin plate. Examples of the poly(meth)acrylic resin plate include a polymethyl(meth)acrylate plate. In the present invention, the inorganic glass is preferable from the viewpoint of safety when it is damaged by being applied with an impact from the outside. In particular, it is considered that the alkali component derived from the glass impairs the thermochromic property, so that the alkali-free glass is more preferable.
Further, it can be applied to other than glass, and can be a composite composed of the whole support of the thermochromic film including glass and the thermochromic film.

[Adhesive layer]
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include an acrylic pressure-sensitive adhesive, a silicon pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a polyvinyl butyral pressure-sensitive adhesive, and an ethylene-vinyl acetate pressure-sensitive adhesive. You can Further, it may be a commercially available product, and for example, a transparent adhesive sheet LUCIACS CS9621T manufactured by Nitto Denko Corporation can be preferably used.

The thermochromic film of the present invention, when pasted to a window glass or the like, spraying water on the window, a method of pasting the adhesive layer of the thermochromic film to the glass surface in a wet state, so-called water pasting method is reattached, and repositioned It is preferably used from the viewpoint of the above. Therefore, an acrylic pressure-sensitive adhesive, which has a weak adhesive force in the presence of water in a wet condition, is preferably used.

The acrylic pressure-sensitive adhesive to be used may be either solvent-based or emulsion-based, but a solvent-based pressure-sensitive adhesive is preferable because it is easy to increase the adhesive force and the like, and among them, those obtained by solution polymerization are preferable. As a raw material in the case of producing such a solvent-based acrylic pressure-sensitive adhesive by solution polymerization, for example, as a main monomer serving as a skeleton, an acrylic acid ester such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, or ocryyl acrylate, As a comonomer for improving cohesive force, vinyl acetate, acrylonitrile, styrene, methyl methacrylate, etc., to further promote cross-linking and impart stable adhesive force, and to maintain a certain adhesive force even in the presence of water In addition, examples of the functional group-containing monomer include methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl methacrylate, and glycidyl methacrylate. For the adhesive layer of the laminated film, a polymer having a low glass transition temperature (Tg), such as butyl acrylate, is particularly useful as a main polymer because it requires particularly high tackiness.

This adhesive layer contains additives such as stabilizers, surfactants, ultraviolet absorbers, flame retardants, antistatic agents, antioxidants, heat stabilizers, lubricants, fillers, coloring agents, adhesion control agents, etc. You can also let it. In particular, when it is used for window sticking as in the present invention, addition of an ultraviolet absorber is effective also for suppressing deterioration of the thermochromic film due to ultraviolet rays.

The thickness of the adhesive layer is preferably 1 to 100 μm, more preferably 3 to 50 μm. If it is 1 μm or more, the tackiness tends to be improved and a sufficient tackiness can be obtained. On the contrary, when the thickness is 100 μm or less, not only the transparency of the thermochromic film is improved, but also when the thermochromic film is attached to the window glass and then peeled off, cohesive failure does not occur between the adhesive layers, and adhesion to the glass surface is not caused. There is a tendency for the remaining agent to disappear.
Various additives can be added to the pressure-sensitive adhesive, and preferably an ultraviolet absorber and an antioxidant can be contained.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, “parts” or “%” are used, but unless otherwise specified, “parts by mass” or “% by mass” is shown. In addition, the "film" in the following description and table shall mean a thermochromic film. Table 1 shows the haze, light transmittance, and light transmittance change of the composite (thermochromic composite) using the thermochromic film corresponding to the film number.

<<Preparation of thermochromic film>>
[Production of Film 101]
(Preparation of VO ₂ Particle Aqueous Dispersion Liquid 1)
74.9 g of vanadium dioxide particles (VO ₂ , manufactured by Shinko Kagaku Co., Ltd.) were mixed with 425 mL of pure water, 200 g of 300 μm zirconia beads for a bead mill was used, and grinding was performed using an Apex mill (manufactured by Kotobuki Kogyo Co., Ltd.). .. Ammonia water was added to the pulverized particles so that the standard oxidation-reduction potential was 330 mV and the pH at 25° C. was 6.5 to prepare an aqueous dispersion 1 of vanadium dioxide particles.

(Preparation of coating liquid 1 for forming thermochromic layer)
The following constituent materials were sequentially added, mixed and dissolved to prepare a water-based coating liquid 1 for forming a thermochromic layer.
15% by mass of VO ₂ particle aqueous dispersion 1 (solvent: water) 9.0% by mass
5% by mass of polyvinylpyrrolidone/vinyl acetate copolymer S-630
(Manufactured by ISP JAPAN) 76.0 mass%
Organix TC-400 (titanium diisopropoxy bis (triethanol aminate); Matsumoto Fine Chemical Co.) 15.0% by mass

(Formation of thermochromic layer)
On a transparent base material of a polyethylene terephthalate film (U40 manufactured by Toray Co., Ltd., double-sided easy adhesion layer) having a thickness of 50 μm, the coating liquid 1 for forming a thermochromic layer prepared above was dried using an extrusion coater so that the layer thickness after drying was Wet coating is performed under the condition of 1.5 μm, and then hot air of 110° C. is blown for 2 minutes to dry to form a thermochromic layer, and the thermochromic film 1 (film 101 having the configuration shown in FIG. 1 is formed. ) Was produced.

[Production of Film 102]
A thermochromic film 102 was produced in the same manner as in the production of the thermochromic film 101, except that the concentration of TC-400 was changed to 20.0% by mass.

[Production of Film 103]
A thermochromic film 103 was produced in the same manner as in the production of the thermochromic film 102, except that the concentration of TC-400 was set to 21.0% by mass.

[Production of Film 104]
A thermochromic film 104 was produced in the same manner as in the production of the thermochromic film 103, except that the concentration of TC-400 was 1.0% by mass.
[Production of Film 105]
A thermochromic film 105 was produced in the same manner as in the production of the thermochromic film 104, except that the concentration of TC-400 was 0.1% by mass.

[Production of Film 106]
A thermochromic film 106 was prepared in the same manner as in the preparation of the thermochromic film 101, except that Organix TC-510 (titanium aminoethylaminoethanolate; manufactured by Matsumoto Fine Chemical Co., Ltd.) was used instead of TC-400.

[Production of Film 107]
A thermochromic film 107 was produced in the same manner as in the production of the thermochromic film 104, except that TC-510 was used instead of TC-400.

[Production of Film 108]
A thermochromic film 108 was prepared in the same manner as the thermochromic film 105 except that TC-510 was used instead of TC-400.

[Production of Film 109]
A thermochromic film 109 was produced in the same manner as in the production of the thermochromic film 101 except that ZC-300 was used instead of TC-400.

[Production of Film 110]
A thermochromic film 110 was produced in the same manner as in the production of the thermochromic film 104 except that ZC-300 was used instead of TC-400.

[Production of Film 111]
A thermochromic film 111 was produced in the same manner as in the production of the thermochromic film 105, except that ZC-300 was used instead of TC-400.

[Production of Film 112]
In the production of the thermochromic film 101, the thermochromic film 112 was produced in the same manner except that Organix ZC-540 (zirconium tributoxy monoacetylacetonate; manufactured by Matsumoto Fine Chemical Co., Ltd.) was used instead of TC-400. ..

[Production of Film 113]
A thermochromic film 113 was produced in the same manner as in the production of the thermochromic film 104 except that ZC-540 was used instead of TC-400.

[Production of Film 114]
A thermochromic film 114 was produced in the same manner as in the production of the thermochromic film 105, except that ZC-540 was used instead of TC-400.

[Production of Film 115 (Comparative Examples 1 to 3)]
A thermochromic film 115 was produced in the same manner as in the production of the thermochromic film 101 except that TC-400 was not added.

[Production of Film 116 (Comparative Example 4)]
A thermochromic film 116 was prepared in the same manner as in the preparation of the thermochromic film 101, except that a titanate coupling agent (Planeact TTS (manufactured by Ajinomoto Fine-Techno Co., Inc.)) was added in place of TC-400 in an amount of 4.0% by mass. Was produced.

[Production of Film 117 (Comparative Example 5)]
A thermochromic film was prepared in the same manner as in the preparation of the thermochromic film 1, except that 0.5% by mass of polycarboxylic acid (Marialim series (AFB-0561) manufactured by NOF CORPORATION) was added in place of TC-400. 117 films were made.
Table 1 shows the configurations of the thermochromic films 101 to 117 produced as described above.

<<Preparation of Thermochromic Complex>>
Each of the prepared thermochromic films 101 to 117 was applied to a transparent adhesive sheet (manufactured by Nitto Denko Corporation) in a size of 15 cm×20 cm of a glass plate having a thickness of 1.3 mm (manufactured by Matsunami Glass Industry Co., Ltd., “Slide glass white edge polishing”). , LUCIACS CS9621T). At that time, the VO ₂ containing layer was attached to the adhesive surface, and the polyethylene terephthalate was attached so as to face outward, and thermochromic composite bodies 201 to 214, 217, 220 and 221 were prepared for each of the prepared thermochromic films (FIG. 3).
As the thermochromic composite 215, a thermochromic film 101 was used to form an adhesive layer on the side of the transparent substrate opposite to the surface on which the VO ₂ containing layer was formed, and the thermochromic film 101 was attached to glass (see FIG. 4 ). Further, the thermochromic composite 216 was manufactured in the same manner except that the glass of the thermochromic composite 201 was changed to non-alkali glass.
As the thermochromic composite 218 (Comparative Example 2), a thermochromic film 115 was used to form an adhesive layer on the side opposite to the surface on which the VO ₂ containing layer was formed of the transparent substrate, and the thermochromic film 115 was bonded to glass ( (See FIG. 4). Further, the thermochromic composite 219 (Comparative Example 3) was manufactured in the same manner except that the glass of the thermochromic composite 217 (Comparative Example 1) was changed to alkali-free glass.

<< haze measurement >>
Using NDH7000 (manufactured by Nippon Denshoku Co., Ltd.), light was made incident from the surface on which the thermochromic layer was formed, and the haze value of the light at that time was measured. Further, the haze value was measured before and after the lapse of 10 days at 85° C. and 85% RH.

<<Evaluation of light transmittance of thermochromic property>>
Using a spectrophotometer V-670 (manufactured by JASCO Corporation), the light transmittance of each produced thermochromic composite at 25° C. (room temperature) at a wavelength of 1500 nm was measured. Moreover, the light transmittance at a wavelength of 1500 nm at 75° C. (high temperature) was measured using a heating measuring device. Furthermore, the light transmittance was measured before and after 7 days at 85° C. and 85% RH.

<<TEM observation>>
The produced thermochromic film was observed with a transmission electron microscope (TEM, device name: JEM-2000FX, manufacturer: JEOL Ltd.) before and after wet heat analysis (see FIGS. 5A to 5D).
5A and 5C are TEM images of the thermochromic film before wet heat, and FIGS. 5B and 5D are TEM images of the thermochromic film after wet heat at 85° C. and 85% RH.
From the TEM images of FIGS. 5A and 5B, it can be confirmed that the shape of the vanadium dioxide particles has changed from granular to acicular before and after wet heat.
On the other hand, a case of a thermochromic film in which a chelate complex is added to the vanadium dioxide-containing layer is shown in FIGS. 5C and 5D. The shape of the vanadium dioxide particles before wet heat does not show a big difference from the case where the chelate complex is not added, but it was found that the formation of needle-like particles after wet heat was suppressed at 85°C/85%RH. It was

<Evaluation result>
From the results of Table 1, the thermochromic composites 217 to 221 containing no chelate complex in the comparative example have decreased thermochromic properties after the deterioration test at 85° C. and 85% RH, whereas the present invention It was found that the thermochromic composites Nos. 201 to 216 had a small deterioration width and high durability.

Further, when the thermochromic composite 217 (Comparative Example 1) and the thermochromic composite 218 (Comparative Example 2) are compared, Comparative Example 1 has a larger deterioration width after the wet heat test. In Comparative Example 1, the VO ₂ -containing layer is close to glass, whereas in Comparative Example 2, the VO ₂ -containing layer is formed as the outermost layer, so that Comparative Example 1 is less affected by moisture and oxygen. Nevertheless, the deterioration is large. Considering that Comparative Example 3 hardly deteriorates, it is considered that the migration of the alkaline component from the glass is suppressed.
On the other hand, with respect to the thermochromic composite of the present invention, deterioration is suppressed even in the presence of migration of alkali components from glass, and it is proved that the chelate complex is effective in maintaining thermochromic properties, It was found that the thermochromic film of the present invention exhibits excellent thermochromic properties.

Regarding the haze, the thermochromic composites 201 to 216 of the present invention all had a haze change rate of 4.0% or less, and were found to be suitable for practical use.
From the above results, it was shown that by using the method described in the present invention, a thermochromic film having both durability and haze stability could be produced.

INDUSTRIAL APPLICABILITY According to the present invention, a thermochromic film and a thermochromic film composite having both durability and haze stability can be obtained, and can be suitably used for a near infrared light shielding film and the like.

1 Thermochromic film 2 Transparent substrate 3 Thermochromic layer (vanadium dioxide containing layer)
4 near-infrared light shielding layer 5 glass member 6 thermochromic composite B1, B2 binder resin VO _S primary particles VO _M secondary particles

Claims (4)

A thermochromic film containing vanadium dioxide particles exhibiting thermochromic properties,
Together with the vanadium dioxide particles, have a vanadium dioxide-containing layer containing a chelate complex, and,
Content of the said chelate complex exists in the range of 0.1-20 mass% with respect to the total mass of the said vanadium dioxide containing layer, The thermochromic film characterized by the above-mentioned. The content of the chelate complex is thermochromic film according to claim 1, relative to the total weight of the vanadium dioxide-containing layer, characterized in that it is in the range of 1 to 15 wt%. A thermochromic composite, which is a composite in which the thermochromic film according to claim 1 or 2 is bonded to glass. The thermochromic composite according to claim 3 , which is a composite in which a thermochromic film having an adhesive layer adjacent to the vanadium dioxide-containing layer is bonded to the glass.

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