WO2017073183A1

WO2017073183A1 - Thermochromic film and method for producing thermochromic film

Info

Publication number: WO2017073183A1
Application number: PCT/JP2016/076629
Authority: WO
Inventors: 保彦高向
Original assignee: コニカミノルタ株式会社
Priority date: 2015-10-27
Filing date: 2016-09-09
Publication date: 2017-05-04
Also published as: JPWO2017073183A1

Abstract

The present invention addresses the problem of providing a thermochromic film that exhibits high thermochromic responsiveness while keeping haze low, and a method for producing said thermochromic film. This thermochromic film is characterized by containing thermochromic vanadium dioxide particles and a block copolymer having a partial structure represented by general formula (I). General formula (I) -(A)a-(B)b-(C)c-

Description

Thermochromic film and method for producing thermochromic film

The present invention relates to a thermochromic film and a method for producing a thermochromic film, and more particularly to a thermochromic film that exhibits excellent thermochromic properties.

In recent years, in order to reduce the heat felt by human skin due to the influence of sunlight entering from a car window, laminated glass having high heat insulating properties or heat shielding properties has been distributed in the market. Recently, with the spread of electric vehicles and the like, development of near-infrared light (heat ray) shielding films applied to laminated glass has been actively conducted from the viewpoint of increasing the cooling efficiency in the vehicle.
The near-infrared light shielding film can be applied to a vehicle body or a window glass of a building to reduce a load on a cooling facility such as an air conditioner in the vehicle, and is an effective means for energy saving.

So, in winter when the temperature in the room or in the car is low, if you want to capture sunlight as much as possible into the room, capture the incident light, and if the temperature in the summer increases, block the incident light. Thermochromic materials that can be used are attracting attention.
The thermochromic material can control near-infrared light shielding and transmission optical properties by temperature, and a typical material thereof is vanadium dioxide (hereinafter also referred to as “VO ₂ ”). . VO ₂ is known to undergo a phase transition in a temperature range of around 60 ° C. and exhibit thermochromic properties.

For example, the thermochromic film described in Patent Document 1 improves the chemical stability and dispersibility of vanadium dioxide particles by organically modifying long-chain molecules on the surface of vanadium dioxide nanoparticles.
However, the thermochromic film described in Patent Document 1 has a slow thermochromic response with a change in infrared transmittance, and further performance improvement is required.

Special table 2015-513508 gazette

The present invention has been made in view of the above-described problems and situations, and a solution to the problem is a thermochromic film exhibiting high thermochromic responsiveness while suppressing haze, and a manufacturing method for manufacturing the thermochromic film. Is to provide.

As a result of studying the cause of the above-mentioned problems in order to solve the above-mentioned problems, the present inventor has found that the thermochromic film of the present invention has vanadium dioxide particles exhibiting thermochromic properties and a partial structure represented by the following general formula (I) It has been found that by containing a block copolymer having a high thermochromic responsiveness while keeping the haze low, the present invention has been achieved.
That is, the said subject of this invention is solved by the following means.

1. A thermochromic film comprising vanadium dioxide particles exhibiting thermochromic properties and a block copolymer having a partial structure represented by the following general formula (I).
Formula (I)
-(A) a-(B) b-(C) c-
[Wherein, A, B and C each represent a repeating unit structure of a monomer constituting the block copolymer. A represents a repeating unit structure of a hydrophobic unsaturated monomer selected from the group consisting of styrenes and alkylene esters. B represents a repeating unit structure of a hydrophilic unsaturated monomer containing a nonionic group. C represents the repeating unit structure of the adsorptive unsaturated monomer containing an amino group or a nitrogen-containing heterocyclic group. a, b and c represent the constituent molar ratio (mol%) of the repeating unit structure of each monomer in the block copolymer, and the total of the constituent molar ratios of a, b and c is 100 mol%. . ]

2. 2. The thermochromic film according to item 1, wherein C represents a unit structure of 4-vinylpyridine.

3. The thermochromic film according to

claim

1 or 2, wherein the vanadium dioxide particles further contain an element for adjusting a phase transition temperature.

4. The thermochromic film according to any one of Items 1 to 3, further comprising a hydrophobic binder.

5). A method for producing a thermochromic film for producing the thermochromic film according to Item 4,
Mixing the powder of the vanadium dioxide particles and an organic solvent containing the block copolymer to prepare a dispersion;
Mixing and applying the hydrophobic binder to the dispersion and drying;
A method for producing a thermochromic film, comprising:

6). A method for producing a thermochromic film for producing the thermochromic film according to Item 4,
Adding an aqueous solution containing the block copolymer to an aqueous dispersion in which the vanadium dioxide particles are dispersed, and preparing a mixed solution;
Adding an organic solvent to the mixed solution, moving the vanadium dioxide particles and the block copolymer from an aqueous phase to an organic phase, and separating and extracting the organic phase;
Mixing and applying the hydrophobic binder to the organic phase and drying;
The manufacturing method of the thermochromic film characterized by having.

The above-mentioned means of the present invention can provide a thermochromic film exhibiting high thermochromic responsiveness while suppressing haze, and a production method for producing the thermochromic film.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
When a long chain molecule is organically modified on the surface of vanadium dioxide particles as in Patent Document 1, the chemical stability and dispersibility of vanadium dioxide particles can be improved. However, this involves a change in infrared transmittance in a film state. Responsiveness will decrease. This is because long-chain molecules are chemically bonded to the vanadium dioxide particles, the surface state changes, and it takes a response time from the time when the vanadium dioxide particles reach the phase transition temperature until the thermal barrier effect is exhibited. It is thought to end up.
Therefore, in the present invention, a thermochromic film excellent in high thermochromic responsiveness, chemical stability and dispersibility accompanied by a change in infrared transmittance by allowing the surface of the vanadium dioxide particles and the block copolymer to moderately interact with each other. I guess it was possible to provide.

Schematic sectional view showing an example of the basic configuration of the thermochromic film of the present invention Schematic sectional view showing another example of the basic configuration of the thermochromic film of the present invention Schematic sectional view showing an example of the layer arrangement of a thermochromic film having a near infrared light shielding layer of the present invention Schematic sectional view showing an example of the layer arrangement of a thermochromic film having a near infrared light shielding layer of the present invention Schematic sectional view showing an example of the layer arrangement of a thermochromic film having a near infrared light shielding layer of the present invention

The thermochromic film of the present invention is characterized by containing vanadium dioxide particles exhibiting thermochromic properties and a block copolymer having a partial structure represented by the general formula (I). This feature is a technical feature common to or corresponding to the claimed invention.

As an embodiment of the present invention, it is more preferable that C represents a unit structure of 4-vinylpyridine from the viewpoint of the effect of the present invention.

Further, the vanadium dioxide particles further include an element for adjusting the phase transition temperature, thereby adjusting and optimizing the phase transition temperature, thereby improving the load on the cooling equipment in summer and the heating equipment in winter. It is more preferable from the point that both load can be reduced and energy saving measures can be taken.

Further, it is preferable to further contain a hydrophobic binder from the viewpoint of improving the compatibility with the vanadium dioxide particles and further improving the haze and thermochromic responsiveness.

The method for producing a thermochromic film for producing the thermochromic film of the present invention comprises a step of mixing a powder of the vanadium dioxide particles and an organic solvent containing the block copolymer to prepare a dispersion, And the step of mixing and applying the hydrophobic binder to the dispersion and applying / drying is preferable in that moisture can be eliminated as much as possible and haze and thermochromic responsiveness can be further improved.

The method for producing a thermochromic film for producing the thermochromic film of the present invention includes a step of adding an aqueous solution containing the block copolymer to an aqueous dispersion in which the vanadium dioxide particles are dispersed to prepare a mixed solution. Adding an organic solvent to the mixed solution, moving the vanadium dioxide particles and the block copolymer from an aqueous phase to an organic phase, separating and extracting the organic phase, and adding the hydrophobic binder to the organic phase. It is more preferable from the viewpoint of haze improvement that it can be used without agglomerating the vanadium dioxide particles.

<Overview of thermochromic film configuration>
The thermochromic film of the present invention comprises vanadium dioxide particles exhibiting thermochromic properties and a block copolymer having a partial structure represented by the following general formula (I).
Formula (I)
-(A) a-(B) b-(C) c-
In the formula, A, B and C each represent a repeating unit structure of a monomer constituting the block copolymer. A represents a repeating unit structure of a hydrophobic unsaturated monomer selected from the group consisting of styrenes and alkylene esters. B represents a repeating unit structure of a hydrophilic unsaturated monomer containing a nonionic group. C represents the repeating unit structure of the adsorptive unsaturated monomer containing an amino group or a nitrogen-containing heterocyclic group. a, b and c represent the constituent molar ratio (mol%) of the repeating unit structure of each monomer in the block copolymer, and the total of the constituent molar ratios of a, b and c is 100 mol%. .

Specific examples of A to C representing the repeating unit structure of the monomer are given below. In addition, the repeating unit structure of a monomer means the structure of the bond unit in the polymer when the monomer forms a polymer.
A may be a repeating unit structure of a hydrophobic unsaturated monomer selected from the group consisting of styrenes and alkylene esters, such as styrene and styrene derivatives (for example, α-methylstyrene or vinyltoluene), vinyl ester of carboxylic acid. (E.g. vinyl acetate, vinyl propionate), vinyl halides, ethylenically unsaturated monocarboxylic acids and dicarboxylic acids (e.g. acrylic acid, methacrylic acid, itaconic acid, maleic acid or fumaric acid) and alkanols of the aforementioned dicarboxylic acids Monoalkyl esters and the like (preferably having 1 to 4 carbon atoms) can also be preferably used.

B may be a repeating unit structure of a hydrophilic unsaturated monomer containing a nonionic group, and a monomer having a group selected from the group consisting of a hydroxy group, an alkylene oxide group, and an amide group (for example, hydroxymethyl acrylate, Hydroxyethyl acrylate, acrylamide, methacrylamide, N-methylolacrylamide or methacrylamide, N-alkylacrylamide, and vinylamine amide (eg, vinylformamide, vinylacetamide) are preferable, and are represented by the following general formula (II) It is also preferable to have a structure.

In the general formula (II), n represents a number of 1 to 100, and R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group. R ₃ represents a hydrogen atom or an alkyl group having 1 to 24 carbon atoms (eg, methyl, ethyl, n- or iso-isopropyl, n-, iso- or tert-butyl, n-, or neo-pentyl, n- Dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl), or aryl-alkyl group having 1 to 24 carbon atoms (for example, benzyl or phenyl-n-nonyl, alkylaryl having 1 to 24 carbon atoms) , Alkylaryl having 1 to 24 carbon atoms, alkyl having 1 to 24 carbon atoms, and the like.

C may be a repeating unit structure of an unsaturated adsorbing monomer containing an amino group or a nitrogen-containing heterocyclic group, and is an unsaturated ethylene containing a primary to quaternary amino group or a nitrogen-containing heterocyclic group. Monomers such as aminoalkyl (meth) acrylate, aminoalkyl (meth) acrylamide (acrylic acid or dimethylaminoethyl methacrylate, acrylic acid or di-t-butylaminoethyl methacrylate, or dimethylaminomethylacrylamide or methacrylamide) , Bitter ionic monomers (eg, sulfopropyl (dimethyl) aminopropyl acrylate, acrylonitrile, 4-aminostyrene, 4-dimethylaminostyrene, 4-vinylpyridine, 2-vinylpyridine and 1-vinylimidazole), It is preferably an ethylenically unsaturated amino monomers selected from the group consisting of methylaminoethyl acrylate, among which, particularly preferably 4-vinyl pyridine.

<Overview of thermochromic film layer structure>
The thermochromic film of the present invention contains at least vanadium dioxide particles and a block copolymer having a partial structure represented by the general formula (I), and preferably further contains a hydrophobic binder. .
The typical structural example of the thermochromic film of this invention is demonstrated with reference to figures.
One of the preferable aspects of the thermochromic film of this invention is the structure by which the optical function layer is formed on the transparent base material.
FIG. 1 is a schematic cross-sectional view showing an example of a basic configuration of a thermochromic film containing vanadium dioxide particles.

A thermochromic film 1 shown in FIG. 1 has a configuration in which an optical functional layer 3 is laminated on a transparent substrate 2. The optical functional layer 3 is present in a state where vanadium dioxide particles are dispersed in the hydrophobic binder B1. 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), dioxide secondary particles VO _M of vanadium is present. In the present invention, an aggregate of two or more vanadium dioxide particles is collectively referred to as secondary particles, and is also referred to as secondary particle aggregates or secondary aggregate particles.
In the present invention, the number average particle size by all the particles of the primary particles VO _S and secondary particles VO _M of vanadium dioxide particles in the optical functional layer 3 is preferably at 200nm or less.

In the present invention, the average particle size of the vanadium dioxide particles in the optical functional layer can be determined according to the following method.
First, the side surface of the optical functional layer 3 constituting the thermochromic film 1 is trimmed with a microtome to expose a cross section as shown in FIG. Next, the exposed cross section is photographed at 10,000 to 100,000 times using a transmission electron microscope (TEM). The particle size of all vanadium dioxide particles present in a certain area of the photographed cross section is measured. At this time, the vanadium dioxide particles to be measured are preferably in the range of 50 to 100 particles. The shot particles, the primary particles are single particles, as shown in FIG. 1, includes a with a two or more particles of the aggregate secondary particles, the particle size of the primary particles VO _S vanadium dioxide Measure the diameter of each independent particle. If it is not spherical, the projected area of the particle is converted into a circle, and its diameter is taken as the particle size. On the other hand, for vanadium dioxide in which two or more particles are aggregated, the projected area of the entire aggregate is obtained, and then the projected area is converted into a circle, and the diameter is taken as the particle size. The number average diameter is obtained for each diameter of the primary particles and secondary particles obtained as described above. Since the cut-out cross-sectional portion has a variation in particle distribution, such measurement is performed for 10 different cross-sectional regions, the whole number-average diameter is obtained, and this is the number-average particle size (nm) referred to in the present invention. It was.

Although details of the vanadium dioxide particles according to the present invention will be described later, the particle size of the primary particles is preferably in the range of 10 to 100 nm. Accordingly, the particle size of the secondary particles varies depending on the number of aggregated particles, but is preferably in the range of 50 to 500 nm.
The thermochromic film of the present invention preferably has a near-infrared light shielding layer having a function of shielding at least part of the light wavelength range of 700 to 1000 nm in addition to the optical functional layer.
Another preferred embodiment of the thermochromic film of the present invention has a hybrid configuration in which the optical functional layer also functions as a resin base material.

FIG. 2 is a schematic cross-sectional view showing another example of the basic configuration of the thermochromic film of the present invention, in which the transparent substrate 2 and the optical functional layer 3 shown in FIG. 1 are formed of the same layer. Is composed of a hybrid optical functional layer (2 + 3), and the polymer constituting the transparent substrate is made of a hydrophobic binder B2, and vanadium dioxide particles are present independently in the hydrophobic binder B2. a primary particle VO _S vanadium dioxide is, two or more secondary particles VO _M is dispersed in vanadium dioxide particles, in the configuration forming the optical functional layer having both a transparent substrate functions as a single layer .

FIG. 3 is a schematic cross-sectional view showing a typical layer arrangement of a thermochromic film having the near-infrared light shielding layer together with the optical functional layer 3 on the transparent substrate in the configuration shown in FIG.
The thermochromic film 1 shown in FIG. 3A has a configuration in which the optical functional layer 3, the near-infrared light shielding layer 4, and the transparent substrate 2 are arranged in this order from the light incident side L.
The thermochromic film 1 shown in FIG. 3B is an example in which the optical functional layer 3 according to the present invention is disposed between the transparent substrate 2 and the near-infrared light shielding layer 4, and FIG. This is an example in which the near-infrared light shielding layer 4 is disposed on the light incident side L and the optical functional layer 3 according to the present invention is disposed on the back surface side of the transparent substrate 2.

As a thermochromic film of this invention, you may provide various functional layers as needed other than each structure layer demonstrated above.
The total thickness of the thermochromic film of the present invention is not particularly limited, but is in the range of 10 to 1500 μm, preferably in the range of 20 to 1000 μm, more preferably in the range of 30 to 500 μm, Particularly preferably, it is in the range of 40 to 300 μm.

As the optical characteristics of the thermochromic film of the present invention, the visible light transmittance measured by JIS R3106 (1998) is preferably 30% or more, more preferably 50% or more, and further preferably 60% or more. It is.

<Each component of thermochromic film>
The thermochromic film of the present invention contains vanadium dioxide particles and a block copolymer having a structure represented by the general formula (I).
Furthermore, it is preferable to have a near-infrared light shielding layer having a function of shielding at least part of the light wavelength range of 700 to 1000 nm.
Hereinafter, the details of the optical functional layer, which is a constituent element of the thermochromic film of the present invention, a resin base material provided if necessary, and the near infrared light shielding layer will be described.

[Optical function layer]
The optical functional layer according to the present invention preferably contains vanadium dioxide particles and a block copolymer having a partial structure represented by the general formula (I).

[Vanadium dioxide particles]
The optical functional layer is preferably present in a state where vanadium dioxide particles are dispersed in a binder resin.
The crystal form of the vanadium dioxide particles according to the present invention is not particularly limited, but rutile vanadium dioxide particles (VO ₂ particles) may be used from the viewpoint of efficiently expressing thermochromic properties (automatic light control). Is particularly preferred.
Since the rutile VO ₂ particles have a monoclinic structure below the phase transition temperature, they are also called M-type. The vanadium dioxide particles according to the present invention may contain VO ₂ particles of other crystal types such as A-type or B-type within a range that does not impair the purpose.

In the present invention, the number average particle size of the primary particles and secondary particles of the vanadium dioxide particles in the optical functional layer is preferably 200 nm or less, more preferably in the range of 1 to 180 nm, still more preferably 5 Within the range of ˜100 nm.
The average particle diameter of the vanadium dioxide particles can be determined according to the method described above.

In the thermochromic film of the present invention, the primary particle number ratio of vanadium dioxide particles in the optical functional layer, which can be determined by the measurement method, is 30% by number or more of the total number of primary particles and secondary particles. Preferably, it is 50% by number or more, particularly preferably 70% by number or more. The ideal upper limit is 100% by number, but the current maximum value is 95% by number or less.

Further, the aspect ratio of the vanadium dioxide particles is preferably in the range of 1.0 to 3.0.
Since vanadium dioxide particles having such characteristics have a sufficiently small aspect ratio and isotropic shape, the dispersibility when added to a solution is good. In addition, since the single crystal has a sufficiently small particle size, it can exhibit better thermochromic properties than conventional fine particles.

In the vanadium dioxide particles according to the present invention, in addition to vanadium dioxide (VO ₂ ), 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 contain at least one element selected from the group consisting of The addition of such an element is effective in that the phase transition characteristics (particularly the phase transition temperature) of the vanadium dioxide particles can be controlled. The total amount of such additives with respect to the finally obtained vanadium dioxide particles is sufficient to be about 0.1 to 5.0 atomic% with respect to the vanadium (V) atom.

The concentration of the vanadium dioxide particles in the optical functional layer is not particularly limited, but is generally preferably within the range of 5 to 60% by mass, more preferably 5 to 40% by mass with respect to the total mass of the optical functional layer. %, More preferably in the range of 5 to 30% by mass.

[Method for producing vanadium dioxide particles]
In general, the method for producing vanadium dioxide particles includes a method of pulverizing a VO ₂ sintered body synthesized by a solid phase method, and a vanadium compound such as divanadium pentoxide (V ₂ O ₅ ) or ammonium vanadate as a raw material. An aqueous synthesis method in which particles are grown while synthesizing VO ₂ in a liquid phase using an aqueous solution instead of an organic solvent is preferably used.
The aqueous synthesis method is preferable in that the average primary particle size is small and variation in particle size can be suppressed.

Furthermore, examples of the aqueous synthesis method include a hydrothermal synthesis method and an aqueous synthesis method using a supercritical state. Details of an aqueous synthesis method using a supercritical state (also referred to as a supercritical hydrothermal synthesis method). For example, reference can be made to the production methods described in paragraph numbers (0011) and (0015) to (0018) of JP-A No. 2010-58984.

Among the above aqueous synthesis methods, in the present invention, the hydrothermal synthesis method is applied and the aqueous synthesis method is used to prepare an aqueous dispersion containing vanadium dioxide particles, and the vanadium dioxide particles in the aqueous dispersion are dried. Prepare a solvent dispersion containing vanadium dioxide particles by the process of replacing the solvent, and mix with a hydrophobic binder resin solution in a dispersed state where the vanadium dioxide particles are separated to prepare a coating solution for forming an optical functional layer To do. The optical functional layer according to the present invention in which the number average particle size of the primary particles and the secondary particles of the vanadium dioxide particles is 200 nm or less by forming the optical functional layer using the coating liquid for forming the optical functional layer in this state. Can be formed. In addition, as a method for producing vanadium dioxide particles, if necessary, fine TiO ₂ particles that become the core of particle growth are added as core particles, and vanadium dioxide particles are produced by growing the core particles. You can also.

Next, the details of the method for producing vanadium dioxide particles by a hydrothermal method suitable for the present invention will be described.
Below, the manufacturing process of the vanadium dioxide particle by a typical hydrothermal method is shown.

(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). This solution may be an aqueous solution in which the substance (I) is dissolved in water, or 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 (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 the substance (I) and have a property of being easily dissolved in water.

In the solution (A), an element is added to the finally obtained single crystal fine particles of vanadium dioxide (VO ₂ ). Therefore, the solution (A) may further contain a substance (II) containing the element to be added. 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 ) -containing single crystal fine particles, the thermochromic properties of the vanadium dioxide particles, in particular, the phase transition temperature can be controlled.

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

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

The conditions of the hydrothermal reaction treatment (for example, the amount of reactants, the treatment temperature, the treatment pressure, the treatment time, etc.) are set as appropriate, but the temperature of the hydrothermal reaction treatment is, for example, within the range of 250 to 350 ° C. Preferably, it is in the range of 250 to 300 ° C, more preferably in the range of 250 to 280 ° C. By reducing the temperature, the particle diameter of the obtained single crystal fine particles can be reduced, but if the particle diameter is excessively small, the crystallinity is lowered. The hydrothermal reaction treatment time is preferably in the range of 1 hour to 5 days, for example. Increasing the time can control the particle size and the like of the obtained single crystal fine particles, but an excessively long processing time increases the energy consumption.

Through the

above steps

1 and 2, a dispersion liquid containing single crystal fine particles containing thermochromic vanadium dioxide (VO ₂ ) is obtained.

<Removal of impurities from vanadium dioxide particle dispersion>
The dispersion of vanadium dioxide particles prepared by the above-described aqueous synthesis method contains impurities such as residues generated during the synthesis process, which triggers the generation of secondary aggregated particles when forming the optical functional layer. In some cases, the optical functional layer may deteriorate during long-term storage, and it is preferable to remove impurities in advance at the stage of the dispersion.

As a method for removing impurities in the vanadium dioxide particle dispersion, conventionally known means for separating foreign substances and impurities can be applied. For example, the vanadium dioxide particle dispersion is centrifuged to precipitate vanadium dioxide particles. It is possible to remove impurities in the supernatant and add and disperse the dispersion medium again, or to remove impurities out of the system using an exchange membrane such as an ultrafiltration membrane. From the viewpoint of preventing aggregation, the method using an ultrafiltration membrane is most preferable.

Examples of the material for the ultrafiltration membrane include cellulose, polyethersulfone, and polytetrafluoroethylene (abbreviation: PTFE). Among these, polyethersulfone and PTFE are preferably used.
By applying and drying the aqueous dispersion from which impurities have been removed, vanadium dioxide particle powder can be obtained.

[Method for producing thermochromic film (aqueous)]
Although there is no restriction | limiting in particular as a preparation method of the thermochromic film of this invention, Preferably an optical function layer is formed using a wet coating method. Specific examples of the wet coating method include a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a slide curtain coating method, or US Pat. No. 2,761,419, US Pat. No. 2,761791, and the like. Examples thereof include a slide hopper coating method and an extrusion coating method.

Further, when forming a hybrid optical functional layer that also serves as a resin base material, a solution casting method can be applied, and specific film forming methods include, for example, JP2013-067074A, JP In accordance with the solution casting film forming method described in JP2013-123868A, JP2013-202979A, JP2014-066958A, JP2014-095729A, JP2014-159082A, and the like. Can be formed.

[Method for producing thermochromic film (organic solvent system 1)]
In the present invention, after preparing a dispersion by mixing the powdered vanadium dioxide particles obtained by the above aqueous synthesis method with an organic solvent containing a block copolymer, a hydrophobic binder is further added, and coating is performed. -It is also preferable to form an optical functional layer by drying to produce a thermochromic film.
Also in this case, it is preferable to produce a thermochromic film by a wet coating method. The specific production method is the same as the production method of the water-based thermochromic film.

[Method for producing thermochromic film (organic solvent system 2)]
As a method for producing a thermochromic film using an organic solvent, first, an aqueous dispersion in which vanadium dioxide particles are dispersed without drying an aqueous dispersion in which vanadium dioxide particles are dispersed, obtained by an aqueous synthesis method. An aqueous solution containing a block copolymer is added to the mixture to prepare a mixed solution. Next, an organic solvent is added to the mixed solution to move the vanadium dioxide particles and the block copolymer from the aqueous phase to the organic phase, and the organic phase is separated and extracted. A method of forming a thermochromic film by forming an optical functional layer by mixing a hydrophobic binder with an organic phase and coating and drying is also preferable. As a method for transferring the vanadium dioxide particles and the block copolymer from the aqueous phase to the organic phase, a general liquid separation operation is performed.

[Hydrophobic binder]
In the thermochromic film of the present invention, it is preferable to apply a hydrophobic binder as a binder for holding vanadium dioxide particles.
The hydrophobic binder as used in the present invention refers to a resin having a dissolution amount of less than 1.0 g at a liquid temperature of 25 ° C. with respect to 100 g of water, and more preferably a resin having a dissolution amount of less than 0.5 g. More preferably, the resin has a dissolution amount of less than 0.25 g.
The hydrophobic binder applied to the present invention is preferably a resin polymerized in a curing treatment step using a hydrophobic polymer or a monomer of a hydrophobic binder.

Examples of the hydrophobic polymer applicable to the present invention include polyethylene, polypropylene, ethylene-propylene copolymer, olefin-based polymer such as poly (4-methyl-1-pentene), acrylate-based copolymer; Halogen-containing polymers such as vinyl and chlorinated vinyl resins; Styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyethylene terephthalate, poly Polyesters such as butylene terephthalate and polyethylene naphthalate; polyamides such as nylon 6, nylon 66 and nylon 610; polyacetal; polycarbonate; polyphenylene oxide; polyphenylene sulfide; Polysulfone; Polysulfone; Polyethersulfone; Polyoxybenzylene; Polyamideimide; ABS resin (acrylonitrile-butadiene-styrene resin) or ASA resin (acrylonitrile-styrene-acrylate resin) blended with polybutadiene rubber and acrylic rubber, Cellulosic resins, butyral resins, and the like can be given.

In addition, as one type of hydrophobic binder applicable to the present invention, a resin that is polymerized in a curing process using a monomer of a hydrophobic binder can be exemplified. A typical hydrophobic binder material is a compound that cures upon irradiation with active energy rays. Specific examples include a radical polymerizable compound that is cured by a polymerization reaction with a radical active species and a cationic polymerizable compound that is cured by a cationic polymerization reaction with a cationic active species.

Examples of the radical polymerizable compound include a compound having an ethylenically unsaturated bond capable of radical polymerization. Examples of the compound having an ethylenically unsaturated bond capable of radical polymerization include acrylic acid, methacrylic acid, itaconic acid, and crotonic acid. , Unsaturated carboxylic acids such as isocrotonic acid and maleic acid and their salts, esters, urethanes, amides and anhydrides, acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, unsaturated urethanes, etc. These radically polymerizable compounds are mentioned. Specifically, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, bis (4-acryloxypolyethoxyphenyl) propane, neopentyl glycol Diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol Tetraacrylate, dipentaery Acrylic acid derivatives such as lithol tetraacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, N-methylolacrylamide, diacetoneacrylamide, epoxy acrylate, methyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate , Lauryl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylol Methacryl derivatives such as tan trimethacrylate, trimethylolpropane trimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, and other derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate, triallyl trimellitate Is mentioned.

As the cationic polymerizable compound, various known cationic polymerizable monomers can be used. For example, JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, Examples thereof include epoxy compounds, vinyl ether compounds, oxetane compounds and the like exemplified in JP-A-2001-220526.

It is preferable to contain a photopolymerization initiator together with the above compound. As the photopolymerization initiator, any known photopolymerization initiators published in “Application and Market of UV / EB Curing Technology” (CMC Publishing Co., Ltd., edited by Yoneho Tabata / edited by Radtech Research Association) may be used. it can.

In the present invention, after applying a coating solution for forming an optical functional layer containing each constituent material and a solvent dispersion containing vanadium dioxide particles, for example, on a transparent substrate, thereafter, an activity such as ultraviolet rays or electron beams is applied. Irradiate energy rays. The composition which comprises the optical function layer thin film formed by this hardens | cures rapidly.

As a light source of active energy rays, when irradiating ultraviolet rays, for example, ultraviolet LED, ultraviolet laser, mercury arc lamp, xenon arc lamp, low pressure mercury lamp, fluorescent lamp, carbon arc lamp, tungsten-halogen copying lamp and sunlight are used. Can be used. In the case of curing with an electron beam, it is usually cured with an electron beam having an energy of 300 eV or less, but it can also be cured instantaneously with an irradiation dose of 1 to 5 Mrad.

On the other hand, as another method for forming the optical functional layer according to the present invention, as illustrated in FIG. 2, a solvent dispersion containing vanadium dioxide particles in a hydrophobic resin that is a constituent material of the transparent substrate, and After preparing a dope for film formation by adding and dissolving a solvent, a hybrid optical functional layer that also serves as a resin substrate is prepared by a solution casting method that has been used in the conventional film formation using the dope. A forming method can also be preferably used.

Examples of the hydrophobic binder that can be applied by the above-described method include resin materials that are conventionally used in the formation of thermochromic films, such as polyethylene terephthalate (abbreviation: PET), polyethylene naphthalate (abbreviation: PEN). Such as polyester, polyethylene, polypropylene, cellulose diacetate, cellulose triacetate (abbreviation: TAC), cellulose acetate butyrate, cellulose acetate propionate (abbreviation: CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate, and the like Derivatives, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate (abbreviation: PC), norbornene tree , Polymethylpentene, polyetherketone, polyimide, polyethersulfone (abbreviation: PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic and polyarylate And cycloolefin resins such as Arton (trade name, manufactured by JSR) and Apel (trade name, manufactured by Mitsui Chemicals).

The solvent is not particularly limited, and examples thereof include methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2- Trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2- Examples include propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, and the like.
Using the dope prepared by mixing and preparing the above constituent materials, a hybrid optical functional layer that also serves as a transparent substrate is formed by a solution casting method.

[Other additives for optical functional layers]
Various additives that can be applied to the optical functional layer according to the present invention as long as the effects of the present invention are not impaired are listed below. For example, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, JP-A-57-74192, JP-A-57- No. 878989, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091, JP-A-3-13376, etc. Various surfactants such as cation or nonion, JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, and JP-A-4-242 209266, etc., optical brighteners, sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and other pH adjusters, antifoaming agents Lubricants such as diethylene glycol, antiseptics, antifungal agents, antistatic agents, matting agents, heat stabilizers, antioxidants, flame retardants, crystal nucleating agents, inorganic particles, organic particles, viscosity reducing agents, lubricants, infrared absorbers And various known additives such as dyes and pigments.

<Transparent substrate>
The transparent substrate 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, it is possible to impart flexibility and suitability for production (manufacturing process suitability). From the viewpoint, a transparent resin film is preferable. “Transparent” 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 according to the present invention is preferably in the range of 30 to 200 μm, more preferably in the range of 30 to 100 μm, and still more preferably in the range of 35 to 70 μm. If the thickness of the transparent substrate is 30 μm or more, wrinkles or the like are less likely to occur during handling, and if the thickness is 200 μm or less, the followability to the curved glass surface when bonded to the glass substrate is improved. .

The transparent substrate according to the present invention is preferably a biaxially oriented polyester film, but an unstretched or at least one stretched polyester film can also be used. A stretched film is preferred 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 glass for automobiles, a stretched film is more preferable.

The transparent substrate according to the present invention has a thermal shrinkage within the range of 0.1 to 3.0% at a temperature of 150 ° C. from the viewpoint of preventing generation of wrinkles of the thermochromic film and cracking of the optical functional layer. Preferably, it is in the range of 1.5 to 3.0%, more preferably 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 various resin films are preferably used. For example, polyolefin films (for example, cycloolefin, polyethylene) , Polypropylene, etc.), polyester films (for example, polyethylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride, triacetyl cellulose films, etc. can be used, preferably cycloolefin films, polyester films, triacetyl cellulose films. .
The transparent resin film is preferably coated with the undercoat layer coating solution in-line on one or both sides during the film formation process. In the present invention, undercoating during the film forming process is referred to as in-line undercoating.

《Near-infrared light shielding layer》
In the thermochromic film of the present invention, in addition to the optical functional layer, it is also preferable to provide a near-infrared light shielding layer having a function of shielding at least part of the light wavelength range of 700 to 1000 nm.
For details of the near-infrared light shielding layer applicable to the present invention, for example, JP 2012-131130 A, JP 2012-139948 A, JP 2012-185342 A, JP 2013-080178 A. Reference can be made to constituent elements and formation methods described in JP-A-2014-089347.

《Uses of thermochromic film》
As a use of the thermochromic film of this invention, it can be set as the structure pasted on glass, The glass which bonded this film can be used for a motor vehicle, a rail vehicle, an aircraft, a ship, a building, etc. The glass bonded together can be used for other purposes. The glass on which the film is bonded is preferably used for buildings or vehicles, and can be used for automobile windshields, side glasses, rear glasses, roof glasses, and the like.

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, mold plate glass, netted plate glass, lined plate glass, and colored glass such as green glass. The organic glass is a synthetic resin glass substituted 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.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

《Preparation of thermochromic film》
[Preparation of thermochromic film 101: aqueous]
(Preparation of vanadium dioxide particle dispersion 1)
0.433 g of ammonium vanadate (NH ₄ VO ₃ , manufactured by Wako Pure Chemical Industries, special grade) was mixed with 10 mL of pure water, and further hydrazine hydrate (N ₂ H ₄ · H ₂ O, manufactured by Wako Pure Chemical Industries, Ltd.). , Special grade) 5 mass% aqueous solution was slowly added dropwise to prepare a solution X having a pH value of 9.2 at 23 ° C. The prepared solution X is put in a commercially available autoclave for hydrothermal reaction treatment (HU-25 type, manufactured by Sanai Kagaku Co., which has a 25 mL volume Teflon (registered trademark) inner cylinder in a SUS body) at 100 ° C. Hydrothermal reaction treatment was applied for 8 hours, and subsequently at 270 ° C. for 24 hours.

Next, the obtained reaction product was filtered, and the filtration residue was filtered and washed with water and ethanol. Further, this reaction product was dried at 60 ° C. for 10 hours by using a constant temperature dryer to obtain vanadium dioxide particle powder.

Subsequently, the obtained vanadium dioxide particle powder and ethanol were subjected to ultrasonic dispersion treatment for 30 minutes with an ultrasonic dispersing machine (UH-300 manufactured by SMT Co., Ltd.) and redispersed, and then a silane coupling agent (KBM- 603: N-2- (aminoethyl) -3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and a hydrophilic binder resin aqueous solution (PVA105, manufactured by Kuraray Co., Ltd.) are added at a constant temperature of 60 ° C. with a high-speed stirrer. The mixture was stirred for a period of time, centrifuged to precipitate, and vacuum dried at 60 ° C. to obtain vanadium dioxide particle powder having an amine group atomic group. The mass ratio of vanadium dioxide particles / silane coupling agent / hydrophilic binder resin in the obtained vanadium dioxide particle powder was 10: 1: 0.1. This was prepared by adding vanadium dioxide particles to pure water to a concentration of 3.0% by mass, and subjected to ultrasonic dispersion treatment for 5 minutes with an ultrasonic dispersing machine (UH-300 manufactured by SMT). Re-dispersion was performed to prepare vanadium dioxide particle dispersion 1.

(Preparation of coating solution 1 for forming an optical functional layer)
The following constituent materials were sequentially added, mixed and dissolved to prepare an aqueous optical functional layer forming coating solution 1.
3 mass% vanadium dioxide particle dispersion 1
128 parts by weight 3% by weight boric acid aqueous solution 10 parts by weight 5% by weight hydrophilic binder resin aqueous solution (PVA105, manufactured by Kuraray Co., Ltd.)
60 parts by mass

(Formation of optical functional layer)
On the transparent base material of a polyethylene terephthalate film (Toyobo A4300, double-sided easy-adhesion layer) having a thickness of 50 μm, using an extrusion coater, the above-prepared coating solution 1 for forming an optical functional layer has a layer thickness after drying. Wet application was performed under the condition of 1.5 μm, followed by drying by blowing warm air of 110 ° C. for 2 minutes to form an optical functional layer, and a thermochromic film 101 was produced.

[Preparation of thermochromic films 102-105: aqueous]
In the production of the thermochromic films 102 to 105, vanadium dioxide dispersed in pure water with an ultrasonic disperser (UH-300 manufactured by SMT) instead of the vanadium dioxide particle dispersion 1 used in the production of the thermochromic film 101. Particles were added to the block copolymer solution described in Table 1 so that the vanadium dioxide particle / block copolymer mass ratio was 1: 1, and adjusted to a concentration of 3.0% by mass as vanadium dioxide particles. It was produced in the same manner except that it was changed to (Vanadium dioxide particle dispersions 2 to 5). In Table 1, “M-PEGMA” represents methoxy-polyethylene glycol (550) monoacrylate.

[Preparation of Thermochromic Film 106: Organic Solvent System 1]
(Preparation of vanadium dioxide particle dispersion 6)
The powder of the vanadium dioxide particles obtained in the preparation of the vanadium dioxide particle dispersion 1 was mixed with the methyl ethyl ketone solution of the block copolymer shown in Table 1 and mixed with an ultrasonic disperser (SMH UH-300) for 30 minutes. The mixture was redispersed by ultrasonic dispersion treatment to prepare a vanadium dioxide particle dispersion 6 having a vanadium dioxide particle / block copolymer mass ratio of 1: 1 and 3% by mass as vanadium dioxide particles.
In preparation of the thermochromic film 106, it produced in the same procedure except having changed the coating liquid 1 for optical function layer formation used by preparation of the thermochromic film 101 into the following coating liquid 2 for optical function layer formation.

(Preparation of coating solution 2 for forming an optical functional layer)
The following constituent materials were sequentially added, mixed and dissolved to prepare a solvent-based coating solution 2 for forming an optical functional layer.
3 mass% vanadium dioxide particle dispersion 6
128 parts by mass 5% by mass of hydrophobic binder resin (solvent: methyl ethyl ketone, solute: Byron 200 (amorphous polyester resin, manufactured by Toyobo Co., Ltd.))
60 parts by mass

[Preparation of Thermochromic Film 107: Organic Solvent System 2]
0.433 g of ammonium vanadate (NH ₄ VO ₃ , manufactured by Wako Pure Chemical Industries, special grade) was mixed with 10 mL of pure water, and further hydrazine hydrate (N ₂ H ₄ · H ₂ O, manufactured by Wako Pure Chemical Industries, Ltd.). 5% by weight aqueous solution was slowly added dropwise to prepare a solution having a pH value of 9.2. The prepared solution is put in a commercially available autoclave for hydrothermal reaction treatment (HU-25 type, manufactured by Sanai Kagaku Co., which has a 25 mL volume Teflon (registered trademark) inner cylinder in a SUS body) at 100 ° C. Hydrothermal reaction treatment was performed for 8 hours, and subsequently at 270 ° C. for 24 hours, to prepare an aqueous vanadium dioxide particle aqueous dispersion in which vanadium dioxide particles were dispersed at a concentration of 3.0% by mass.

(Preparation of organic solvent-based vanadium dioxide particle dispersion from aqueous dispersion of vanadium dioxide particles)
The prepared vanadium dioxide particle aqueous dispersion was added to the block copolymer solution described in Table 1 so that the vanadium dioxide particle / block copolymer mass ratio was 1: 1. Methyl ethyl ketone was added thereto, and the mixture was allowed to stand at high speed with a homogenizer. After that, a vanadium dioxide particle methyl ethyl ketone dispersion (organic phase) in which vanadium dioxide particles modified with the block copolymer partially moved from the aqueous phase was separated and extracted. This operation was repeated until the vanadium dioxide particles modified with the block copolymer disappeared from the aqueous phase. The separated and extracted organic phases were combined, and organic solvent-based vanadium dioxide particle dispersion 7 having a vanadium dioxide particle concentration of 3 mass% was prepared by solvent concentration.

(Preparation of coating solution 3 for forming an optical functional layer)
The following constituent materials were sequentially added, mixed and dissolved to prepare a solvent-based coating solution 3 for forming an optical functional layer.
3% by weight of organic solvent-based vanadium dioxide particle dispersion 7 (solvent: methyl ethyl ketone)
28 mass parts 5 mass% hydrophobic binder resin (solvent: methyl ethyl ketone, solute: Byron 200 (amorphous polyester resin, manufactured by Toyobo Co., Ltd.))
60 parts by mass

(Formation of optical functional layer)
On a transparent substrate of a polyethylene terephthalate film (A4300 manufactured by Toyobo Co., Ltd., double-sided easy-adhesion layer) having a thickness of 50 μm, using an extrusion coater, the coating liquid 3 for forming an optical functional layer prepared above has a layer thickness after drying. Wet application was performed under the condition of 1.5 μm, and then dried by blowing hot air at 110 ° C. for 2 minutes to form an optical functional layer, thereby producing a thermochromic film 107 having the configuration shown in FIG. .

[Preparation of thermochromic film 108: aqueous]
The thermochromic film 108 was produced in the same procedure as the thermochromic film 101 except that vanadium dioxide particles containing 0.5% by mass of tungsten were used.

[Preparation of thermochromic film 109: aqueous]
The thermochromic film 109 was produced in the same procedure as the thermochromic film 105 except that vanadium dioxide particles containing 0.5% by mass of tungsten were used.

[Preparation of Thermochromic Film 110: Organic Solvent System 2]
The thermochromic film 110 was produced in the same procedure as the thermochromic film 107 except that vanadium dioxide particles containing 0.5% by mass of tungsten were used.

[Preparation of Thermochromic Film 111: Organic Solvent System 2]
The thermochromic film 111 was produced in the same procedure as the thermochromic film 107 except that vanadium dioxide particles containing 1.0% by mass of molybdenum were used.

[Preparation of Thermochromic Film 112: Organic Solvent System 2]
The thermochromic film 112 was produced in the same procedure as the thermochromic film 107 except that vanadium dioxide particles containing 1.5% by mass of ruthenium were used.

<Evaluation of thermochromic film>
Next, each of the thermochromic films prepared above was subjected to the following evaluations.

(Evaluation of haze)
About each produced said thermochromic film, haze (%) was measured at room temperature using the haze meter (Nippon Denshoku Industries Co., Ltd. make, NDH2000), and the haze was evaluated according to the following reference | standard.
A: Haze is less than 2.0% B: Haze is 2.0% or more and less than 3.0% Δ: Haze is 3.0% or more and less than 5.0% ×: Haze is 5.0% or more

(Thermochromic response)
Thermochromic film bonding glass was arrange | positioned so that the inner side might become a thermochromic film only to one side of the space of 20 cm x 20 cm x 20 cm closed with the vacuum heat insulating material. A thermometer was installed at a position 19 cm away from the thermochromic film-laminated glass inside the heat insulating space, and a 150 W halogen lamp was turned on from a position 10 cm away from the outside where the thermochromic film-laminated glass was placed. The time required for the temperature to rise by 1 ° C. after the halogen lamp was turned on was evaluated according to the following criteria (rank), and the results obtained are shown in Table 1.
◎: 300 seconds or more ○: 120 seconds or more and less than 300 seconds △: 60 seconds or more and less than 120 seconds ×: less than 60 seconds

As is clear from the results shown in Table 1, it was found that the thermochromic film of the present invention exhibited excellent thermochromic responsiveness with a low haze relative to the comparative example.

According to the present invention, a thermochromic film exhibiting excellent thermochromic response can be produced, and can be suitably used for a near infrared light shielding film and the like.

DESCRIPTION OF SYMBOLS 1 Thermochromic film 2 Transparent base material 3 Optical functional layer 2 + 3 Hybrid optical functional layer 4 Near-infrared light shielding layer B1, B2 Hydrophobic binder L Light incident side Primary particle of VO _S vanadium dioxide particle Secondary of VO _M vanadium dioxide particle particle

Claims

A thermochromic film comprising vanadium dioxide particles exhibiting thermochromic properties and a block copolymer having a partial structure represented by the following general formula (I).
Formula (I)
-(A) a-(B) b-(C) c-
[Wherein, A, B and C each represent a repeating unit structure of a monomer constituting the block copolymer. A represents a repeating unit structure of a hydrophobic unsaturated monomer selected from the group consisting of styrenes and alkylene esters. B represents a repeating unit structure of a hydrophilic unsaturated monomer containing a nonionic group. C represents the repeating unit structure of the adsorptive unsaturated monomer containing an amino group or a nitrogen-containing heterocyclic group. a, b and c represent the constituent molar ratio (mol%) of the repeating unit structure of each monomer in the block copolymer, and the total of the constituent molar ratios of a, b and c is 100 mol%. . ]
The thermochromic film according to claim 1, wherein C represents a unit structure of 4-vinylpyridine.
The thermochromic film according to claim 1 or 2, wherein the vanadium dioxide particles further contain an element for adjusting a phase transition temperature.
The thermochromic film according to any one of claims 1 to 3, further comprising a hydrophobic binder.
It is a manufacturing method of the thermochromic film which manufactures the thermochromic film of Claim 4, Comprising:
Mixing the powder of the vanadium dioxide particles and an organic solvent containing the block copolymer to prepare a dispersion;
Mixing and applying the hydrophobic binder to the dispersion and drying;
A method for producing a thermochromic film, comprising:
It is a manufacturing method of the thermochromic film which manufactures the thermochromic film of Claim 4, Comprising:
Adding an aqueous solution containing the block copolymer to an aqueous dispersion in which the vanadium dioxide particles are dispersed, and preparing a mixed solution;
Adding an organic solvent to the mixed solution, moving the vanadium dioxide particles and the block copolymer from an aqueous phase to an organic phase, and separating and extracting the organic phase;
Mixing and applying the hydrophobic binder to the organic phase and drying;
The manufacturing method of the thermochromic film characterized by having.