WO2018092502A1

WO2018092502A1 - Thermochromic composition and thermochromic film

Info

Publication number: WO2018092502A1
Application number: PCT/JP2017/037930
Authority: WO
Inventors: 保彦高向
Original assignee: コニカミノルタ株式会社
Priority date: 2016-11-16
Filing date: 2017-10-20
Publication date: 2018-05-24
Also published as: JP2020012011A

Abstract

The present invention addresses the problem of providing a thermochromic composition and a thermochromic film that produce an improved summer heat shielding effect. The thermochromic composition according to the present invention contains vanadium dioxide particles that exhibit thermochromism, and also contains a conductive material and a resin binder in addition to the vanadium dioxide particles.

Description

Thermochromic composition and thermochromic film

The present invention relates to a thermochromic composition and a thermochromic film. In more detail, this invention relates to the thermochromic composition etc. which improved the heat-insulating effect of summer.

In recent years, for example, in order to reduce the heat felt by human skin due to the influence of sunlight entering from a vehicle window, laminated glass having high heat insulating properties or heat shielding properties has been distributed on 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.

Therefore, in winter when the temperature in the room or in the vehicle decreases, the incident light is taken in to capture sunlight as much as possible into the room, and the incident light is shielded when the temperature in the room in summer increases. Thermochromic films containing thermochromic materials that can be drawn attention.

The thermochromic material refers to a material capable of controlling the optical properties of near-infrared light shielding and transmission by temperature. A typical example of this thermochromic material 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, a thermochromic film in which a thermochromic layer containing vanadium oxide particles is provided on a base material is known (see Patent Document 1). This utilizes the change in optical properties due to the phase transition of vanadium oxide due to the temperature change. It absorbs heat in the near-infrared region (750-2500 nm) of the sun's rays in the summer and shields it in the winter. Light is taken into the room and the heating effect is used.
That is, in summer, the vanadium oxide particles change to the M phase as the temperature rises, and sunlight rays are absorbed around the wavelength of light corresponding to the intrinsic plasma frequency (plasma oscillation frequency) of the M phase vanadium oxide particles. However, the effect was limited because of absorption at a specific wavelength.

Special table 2015-513508 gazette

The present invention has been made in view of the above problems and situations, and a problem to be solved is to provide a thermochromic composition and a thermochromic film having an improved heat shielding effect in summer.

In the present invention, by further containing a conductive substance in the thermochromic layer containing vanadium oxide, light in the near infrared region after the plasma frequency can be reflected rather than absorbed, and the heat shielding effect in summer can be achieved. The present inventors have found that an improved thermochromic composition can be provided and have reached the present invention.
That is, the said subject which concerns on this invention is solved by the following means.

1. A thermochromic composition containing vanadium dioxide particles exhibiting thermochromic properties,
A thermochromic composition containing a conductive substance and a resin binder in addition to the vanadium dioxide particles.

2. The thermochromic composition according to item 1, wherein the carrier concentration (n) at ²³ ° C. is 5 × 10 ²⁰ cm ⁻³ or less.

3. The thermochromic composition according to

Item

1 or 2, wherein the conductive substance contains metal nanofibers, carbon nanotubes, carbon nanobuds, or graphene.

4. The thermochromic composition according to any one of Items 1 to 3, wherein the vanadium dioxide particles contain an element for adjusting a phase transition temperature.

5. A thermochromic film containing the thermochromic composition according to any one of items 1 to 4.

6. The thermochromic film of Claim 5 which has a thermochromic layer containing the said thermochromic composition on a transparent base material.

By the said means of this invention, the thermochromic composition and the thermochromic film which improved the thermal-insulation effect of summer can be provided.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
The vanadium dioxide particles showing thermochromic properties and the conductive material are contained in the same layer, so that the conductivity further increases when the vanadium oxide particles change to the M phase due to temperature rise in summer, and light in the near infrared region. It has been found that a thermochromic composition and a thermochromic film capable of reflecting, rather than absorbing, can be provided.

Relationship between reflectance of light with a wavelength of 800 nm and carrier concentration 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

The thermochromic composition of the present invention is a thermochromic composition containing vanadium dioxide particles exhibiting thermochromic properties, and contains a conductive substance and a resin binder in addition to the vanadium dioxide particles. This feature is a technical feature common to or corresponding to the embodiments of the present invention described below. Thereby, the thermochromic composition and thermochromic film which improved the heat-shielding effect of summer can be provided.

Further, the carrier concentration (n) at 23 ° C. is preferably 5 × 10 ²⁰ cm ⁻³ or less because it can reflect light in the near infrared region in summer.

Moreover, it is preferable that the conductive substance contains metal nanofibers, carbon nanotubes, carbon nanobuds, or graphene because the carrier concentration can be adjusted suitably.

The vanadium dioxide particles preferably contain an element for adjusting the phase transition temperature. This is because by optimizing the phase transition temperature, it is possible to reduce the load on the cooling equipment in summer and promote energy saving.

The thermochromic film of the present invention contains the thermochromic composition of the present invention.

In addition, the thermochromic film of the present invention preferably has a thermochromic layer containing the thermochromic composition on a transparent substrate from the viewpoint of manifesting the effects 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 the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

<Outline of thermochromic composition>
The thermochromic composition of the present invention is a thermochromic composition containing vanadium dioxide particles exhibiting thermochromic properties, and contains a conductive substance and a resin binder in addition to the vanadium dioxide particles.

<Conductive substance>
Examples of the conductive material used in the present invention include metal nanofibers (for example, silver nanofibers and other metal nanofibers such as Cu, Ni, Co, Au, etc.), carbon nanotubes (hereinafter also referred to as “CNT”). Carbon nanobuds (“CNB”, so-called fullerene functionalized carbon nanotubes) and graphene, and the like, and preferably contain metal nanofibers, carbon nanotubes, carbon nanobuds, or graphene. This is because the carrier concentration can be suitably adjusted.

(Carrier concentration)
The carrier concentration (n) of the thermochromic composition at 23 ° C. is preferably 5 × 10 ²⁰ cm ⁻³ or less, and particularly within the range of 5 × 10 ¹⁹ to 5 × 10 ²⁰ cm ⁻³ . In the winter season, the light wavelength range of 2.5 to 25 μm is efficiently reflected to have a heat insulating function, and in the summer season, light in the near infrared region can also be reflected.

(Measurement method of carrier concentration)
The carrier concentration (n) of the thermochromic layer at 23 ° C. in the present invention can be measured by a known method. Specifically, for example, it can be measured using a Hall measuring device (for example, ResiTest 8310 manufactured by Toyo Technica). it can.

The wavelength of the reflected light has a threshold value determined by the plasma frequency (plasma oscillation frequency). For example, a conductive film such as a sputtered metal oxide film such as ITO (indium tin oxide). Then, light with energy lower than that energy is reflected. The plasma frequency ω _p is defined by the following equation.
_{^{^{(Ω p) 2 = nq 2}}} / εm

In the above formula, n represents carrier concentration, q represents carrier charge, ε represents dielectric constant, and m represents electron mass. Here, the above equation is a function of the carrier concentration.
FIG. 1 shows the relationship between carrier concentration and reflectance. For example, the reflectance with respect to light having a wavelength of 800 nm suddenly increases from a carrier concentration of 2 × 10 ²¹ cm ⁻³ , and light on the longer wavelength side is reflected.
However, in a system in which vanadium dioxide particles are dispersed in a resin binder, the conductivity cannot be expressed without contact between the vanadium dioxide particles. Therefore, even if the vanadium dioxide particles change to the M phase, the carrier concentration does not improve, and light rays centered on the wavelength of light corresponding to the intrinsic plasma frequency (plasma oscillation frequency) possessed by the M phase vanadium oxide particles. Only absorption for a so-called specific wavelength is absorbed.

<Vanadium dioxide particles>
One preferred embodiment of the thermochromic layer according to the present invention is an embodiment in which vanadium dioxide is contained in the binder resin as nanoparticles (vanadium dioxide particles). Thereby, the manufacturing freedom degree of a thermochromic material increases and it can show | play the effect of this invention more suitably.
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 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 and secondary vanadium dioxide particles in the thermochromic layer is preferably 200 nm or less, more preferably in the range of 1 to 180 nm, and 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 later.

In the thermochromic film of the present invention, the primary particle number ratio of vanadium dioxide particles in the thermochromic 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.

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

(Elements for adjusting the phase transition temperature)
The vanadium dioxide particles according to the present invention preferably contain an element for adjusting the phase transition temperature.
Examples of elements for adjusting the phase transition temperature include tungsten (W), molybdenum (Mo), niobium (Nb), tantalum (Ta), tin (Sn), rhenium (Re), iridium (Ir), and osmium. Selected from the group consisting of (Os), ruthenium (Ru), germanium (Ge), chromium (Cr), iron (Fe), gallium (Ga), aluminum (Al), fluorine (F) and phosphorus (P) It is preferable that at least one element is contained.
The addition of such elements is effective in that the phase transition characteristics (particularly the phase transition temperature) of the vanadium dioxide particles can be adjusted. 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.

In addition, although it does not specifically limit as an aspect in which a vanadium dioxide particle contains the element for adjusting a phase transition temperature, It is an aspect made to contain by adding the said element when manufacturing the said vanadium dioxide particle. Is preferred.

[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.

Specifically, for example, in the present invention, a hydrothermal synthesis method is applied, and an aqueous dispersion containing vanadium dioxide particles is prepared by an aqueous synthesis method, and 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 a thermochromic layer can do.
In addition, as a method for producing vanadium dioxide particles, vanadium dioxide particles are produced by adding fine particles such as fine TiO ₂ as cores of particle growth as core particles and growing the core particles as necessary. 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. As an element to add, the element for adjusting the below-mentioned phase transition temperature is mentioned, for example.

By adding these elements to the finally obtained vanadium dioxide (VO ₂ ) -containing single crystal fine particles, the thermochromic property of the vanadium dioxide particles, in particular, the phase transition temperature is controlled and adjusted to an optimum one. be able to. In this way, by adjusting and optimizing the phase transition temperature, it is possible to reduce both the load on the cooling facility in summer and the load on the heating facility in winter, thereby further saving energy.

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 water-based synthesis method contains impurities such as residues generated during the synthesis process, which triggers the generation of secondary aggregated particles when forming the thermochromic layer. In some cases, the thermochromic 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.

<Resin binder>
The thermochromic composition of the present invention contains a resin binder.
As the resin binder, either a hydrophilic binder or a hydrophobic binder may be used.

<Hydrophilic binder>
In the present invention, the hydrophilic binder refers to a binder that dissolves 1.0 g or more per 100 g of water at 25 ° C.
Examples of hydrophilic binders include gelatin, graft polymers of gelatin and other polymers, proteins such as albumin and casein, celluloses, sodium alginate, cellulose sulfate, dextrin, dextran, dextran sulfate and other sugar derivatives, Naturally derived materials such as thickening polysaccharides, polyvinyl alcohols, polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer Or acrylic resins such as acrylic acid-acrylic acid ester copolymer, vinyl acetate-acrylic acid ester copolymer, or acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid Mutual weight Styrene-acrylic acid resin such as styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, or styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer Styrene-sodium styrene sulfonate copolymer, styrene-2-hydroxyethyl acrylate copolymer, styrene-2-hydroxyethyl acrylate-potassium styrene sulfonate copolymer, styrene-maleic acid copolymer, styrene-anhydrous maleic acid Acid copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic acid copolymer Vinyl acetate copolymers such as Luo salts.

<Hydrophobic binder>
In the thermochromic composition of the present invention, it is also preferable to apply a hydrophobic binder as a binder for holding the 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), ASA resin (acrylonitrile-styrene-acrylate resin), cellulose blended with polybutadiene rubber and acrylic rubber Resin, butyral resin, and the like.

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, and typical hydrophobic binder materials include active energy. Examples of the compound that is cured by irradiation with a line include a radical polymerizable compound that is cured by a polymerization reaction by a radical active species and a cationic polymerizable compound that is cured by a cationic polymerization reaction by 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 a thermochromic 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 thermochromic 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, curing is usually performed with an electron beam having an energy of 300 eV or less, but it is also possible to cure instantaneously with an irradiation dose of 1 to 5 Mrad.

On the other hand, as another method for forming the thermochromic layer according to the present invention, vanadium dioxide particles and a hydrophilic binder are included in the hydrophobic binder which is a constituent material of the transparent substrate, as illustrated in FIG. After adding and dissolving a solvent dispersion and a solvent to prepare a dope for film formation, a hybrid that also serves as a resin base material by the solution casting method used in the conventional film formation using the dope A method of forming a thermochromic layer can also be suitably 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.

<Outline of thermochromic film>
The thermochromic film of the present invention contains the thermochromic composition of the present invention.
Moreover, it is preferable that the thermochromic film of this invention has a thermochromic layer containing the said thermochromic composition on a transparent base material.

<Overview of thermochromic film layer structure>
The thermochromic film of the present invention may be a thermochromic film consisting only of a thermochromic layer, or may have a thermochromic layer containing a thermochromic composition on a transparent substrate.

A typical configuration example of the thermochromic film of the present invention will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view showing an example of a basic configuration of a thermochromic film containing vanadium dioxide as nanoparticles (hereinafter, these nanoparticles are also referred to as “vanadium dioxide particles”).
A thermochromic film 1 shown in FIG. 2 has a configuration in which a thermochromic layer 3 is laminated on a transparent substrate 2. The thermochromic layer 3 is present in a state where vanadium dioxide particles are dispersed in the binder B1. The vanadium dioxide particles, constitute the primary particles VO _S of vanadium dioxide particles vanadium dioxide particles are present independently, an aggregate of two or more vanadium dioxide particles (also referred to as aggregates.) , there is a secondary particle VO _M of vanadium dioxide particles. 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.

[Thermochromic layer]
The thermochromic layer is not particularly limited as long as it is a layer containing a thermochromic material. For this reason, the thermochromic layer should just be a layer containing vanadium dioxide particle, and it is preferable that it is the layer formed especially by application | coating.
In the present invention, the average particle size of the vanadium dioxide particles in the thermochromic layer can be determined according to the following method.
First, the side surface of the thermochromic layer 3 is trimmed by 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. 2, 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 was performed for 10 different cross-sectional regions, the whole number-average diameter was obtained, and this was defined as the number-average particle size (nm).

The primary particle size of the vanadium dioxide particles according to the present invention 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.

Another preferred embodiment of the thermochromic film of the present invention has a hybrid configuration in which the thermochromic layer also functions as a resin base material.
For example, as shown in FIG. 3, it is good also as a thermochromic film which has the hybrid thermochromic layer comprised by making the transparent base material 2 shown in FIG. 2, and the thermochromic layer 3 into the same layer.
In order to form such a hybrid thermochromic layer, a resin binder such as a polymer constituting a transparent substrate is used, and vanadium dioxide particles in which vanadium dioxide particles are independently present in the resin binder B2. a primary particle VO _S, 2 or more of the secondary particles VO _M of vanadium dioxide particles are dispersed may be the thermochromic layer having both a transparent substrate functions as a single layer. The resin binder used here is preferably a hydrophobic binder.
It is also preferable to form a hybrid thermochromic layer that also serves as a transparent substrate by a solution casting method using a dope prepared by mixing and preparing each constituent material.

<Other additives for thermochromic layer>
Various additives that can be applied to the thermochromic 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.

[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 a thermochromic layer is formed using the wet apply | 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.

[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-mentioned 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 a thermochromic film by drying to form 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. And the method of forming a thermochromic layer by mixing a hydrophobic binder with an organic phase, apply | coating and drying, and producing a thermochromic film 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.

Further, when forming a hybrid thermochromic 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.

[Other layer structure of thermochromic film]
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.

<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 a 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 thermochromic 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.

《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.

Note that embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.

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.

<< Production of thermochromic films 1-8 >>
The method for producing thermochromic films 1 to 8 will be described below. In the following examples and tables, the term “film” simply represents a thermochromic film.

[Preparation of Thermochromic Film 1]
<Preparation of vanadium dioxide particle dispersion 1>
Pure water 10 mL, ammonium vanadate _(NH 4 VO _3, manufactured by Wako Pure Chemical Industries, Ltd., special grade) 0.433 g were mixed, further, hydrazine hydrate _{_{_{(N 2 H 4 · H 2}}} O, Wako Pure Chemical Industries, A 5% by mass aqueous solution of a special grade) 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 a silane coupling agent (KBM-603) was added thereto. : 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.), and at a constant temperature of 60 ° C. for 2 hours with a high-speed stirrer Stirring, centrifuging and precipitating, and vacuum drying at 60 ° C. yielded vanadium dioxide particles having amine group atomic groups. 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 is prepared by adding vanadium dioxide particles to pure water so as to have a concentration of 3.0% by mass, redispersed by ultrasonic dispersion treatment for 5 minutes with the above ultrasonic disperser, and dispersed in vanadium dioxide particles. Liquid 1 was prepared.

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

<Formation of thermochromic layer>
On the transparent substrate, the prepared thermochromic layer forming coating solution 1 is wet-coated under the condition that the layer thickness after drying is 1.5 μm, and then dried by blowing hot air at 110 ° C. for 2 minutes. Thus, a thermochromic layer was formed to produce a thermochromic film 1.

[Preparation of Thermochromic Film 2]
The thermochromic film 2 was prepared except that after the preparation of the vanadium dioxide particle dispersion 1, a dispersion of silver nanofibers (diameter 40 nm, length 40 μm) was added to 6.0 × 10 ²⁰ cm ^−3. The same procedure as for thermochromic film 1 was performed.

[Preparation of Thermochromic Film 3]
The thermochromic film 3 was produced in the same manner as the thermochromic film 2 except that an aqueous dispersion of silver nanofibers was added to 5.0 × 10 ²⁰ cm ⁻³ .

[Preparation of Thermochromic Film 4]
The thermochromic film 4 was prepared in the same manner as the thermochromic film 2 except that an aqueous dispersion of carbon nanotubes was added to 3.0 × 10 ²⁰ cm ⁻³ .

[Preparation of Thermochromic Film 5]
The thermochromic film 5 was produced in the same procedure as the thermochromic film 2 except that an aqueous dispersion of carbon nanobuds was added to 4.0 × 10 ²⁰ cm ⁻³ .

[Preparation of Thermochromic Film 6]
The thermochromic film 6 was produced in the same procedure as the thermochromic film 2 except that an aqueous dispersion of graphene was added so as to be 3.5 × 10 ²⁰ cm ⁻³ .

[Preparation of Thermochromic Film 7]
The thermochromic film 7 was produced in the same procedure as the thermochromic film 3 except that vanadium dioxide particles containing 0.5 at% (atomic concentration) of tungsten were used.

[Preparation of thermochromic film 8]
The thermochromic film 8 was produced in the same procedure as the thermochromic film 3 except that vanadium dioxide particles containing 0.5 at% molybdenum were used.

[Evaluation methods]
(Phase transition temperature)
The spectral transmittance of the obtained thermochromic film was changed using a spectral transmittance meter V-770 manufactured by JASCO Corporation, and the change in light transmittance at a wavelength of 1500 nm in the near infrared region was changed from 25 ° C. to the heating temperature. The temperature at which the light transmittance did not change was defined as the phase transition temperature of the thermochromic film.

(Carrier concentration)
The carrier concentration of the infrared reflective layer was measured by measuring the carrier concentration of the film at room temperature by the Van der Pauw method using a Hall effect measuring device (ResiTest manufactured by Toyo Technica Co., Ltd.).

(Solar heat acquisition rate difference)
The solar heat acquisition rate (η) is a numerical value indicating the ratio of the amount of heat flowing into the room (the sum of direct transmission and indoor re-radiation) when the solar radiation incident on the glass is 1.0. In accordance with JIS R3106 (Testing methods for transmittance, reflectance, and solar heat gain of glass), the thermochromic film obtained on a transparent glass with a thickness of 3 mm was attached and evaluated, and before and after the phase transition temperature 5 The difference in the solar heat gain rate at ° C was determined. It shows that there is a heat-shielding effect, so that this figure is large.

(Evaluation of heat transmissibility)
The obtained thermochromic film was measured for the heat transmissivity according to “JIS A 5759: 2008 Film for architectural window glass”. It shows that there exists a heat insulation effect, so that this figure is small.

(Summary)
From the above results, according to the present invention, it is possible to provide a thermochromic film having a large difference in the rate of solar heat acquisition and an improved heat shielding effect in summer. Moreover, since the heat transmissivity is small, a thermochromic film having a high heat insulating effect can be provided.

The thermochromic film containing the thermochromic composition of the present invention can be configured to be pasted on glass. The glass bonded with the thermochromic film can be used for automobiles, railway vehicles, aircraft, ships, buildings, and the like. For example, when the glass bonded with the thermochromic film is used in an automobile, it can be used for an automobile windshield, side glass, rear glass, roof glass, or the like.

DESCRIPTION OF SYMBOLS 1 Thermochromic film 2 Transparent base material 3 Thermochromic layer B1, B2 Resin binder VO _S Primary particle of vanadium dioxide particle Secondary particle of VO _M vanadium dioxide particle

Claims

A thermochromic composition containing vanadium dioxide particles exhibiting thermochromic properties,
A thermochromic composition containing a conductive substance and a resin binder in addition to the vanadium dioxide particles.
The thermochromic composition according to claim 1, wherein the carrier concentration (n) at 23 ° C. is 5 × 10 20 cm −3 or less.
The thermochromic composition according to claim 1 or 2, wherein the conductive substance contains metal nanofibers, carbon nanotubes, carbon nanobuds, or graphene.
The thermochromic composition according to any one of claims 1 to 3, wherein the vanadium dioxide particles contain an element for adjusting a phase transition temperature.
A thermochromic film containing the thermochromic composition according to any one of claims 1 to 4.
The thermochromic film according to claim 5, which has a thermochromic layer containing the thermochromic composition on a transparent substrate.