JP2019135272A - Thermochromic vanadium dioxide-containing particles and production method therefor, and thermochromic film and production method therefor - Google Patents

Abstract

To provide: thermochromic vanadium dioxide-containing particles that have superior storage stability and high thermochromic responsiveness; a production method therefor; a thermochromic film using the thermochromic vanadium dioxide-containing particles; and a production method therefor.SOLUTION: The thermochromic vanadium dioxide-containing particles according to the present invention are each characterized by having a core-shell structure, where the core-shell structure has a vanadium dioxide particle in the core, and has, on a surface of it, a multilayer structure of having a first shell layer which modifies the surface of the vanadium dioxide particle by an organic compound having at least a hydroxy group and a second shell layer containing an amorphous metal oxide, in this order.SELECTED DRAWING: Figure 1

Description

  The present invention relates to thermochromic vanadium dioxide-containing particles and a production method thereof, and a thermochromic film and a production method thereof. More specifically, the present invention relates to thermochromic properties having excellent storage stability and high thermochromic response. The present invention relates to vanadium dioxide-containing particles, a production method thereof, a thermochromic film using the same, and a production method thereof.

  In recent years, glass or a film that is bonded to glass that has a high heat insulating property or a heat insulating property that blocks the heat felt by human skin due to the influence of sunlight entering from the vehicle window has been distributed in the market. Recently, with the widespread use of electric vehicles and the like, development of near-infrared light (heat ray) shielding films applied to glass has been actively conducted from the viewpoint of increasing the cooling efficiency in the vehicle.

  By applying the near-infrared light shielding film to the window glass of a vehicle body or a building, it is possible to reduce the load on the cooling equipment such as an air conditioner in the vehicle, which is an effective means for saving energy.

  As such a near-infrared shielding film, an optical film containing a conductor such as ITO (tin-doped indium oxide) as an infrared absorbing substance is disclosed. Japanese Unexamined Patent Application Publication No. 2010-222233 discloses a near-infrared light shielding film including a functional plastic film having an infrared reflection layer and an infrared absorption layer.

  On the other hand, it has a reflective layer stack in which a large number of low refractive index layers and high refractive index layers are alternately stacked, and selectively reflects near infrared light by adjusting the thickness of each refractive index layer. A near infrared light shielding film is proposed in International Publication No. 2013/065679.

  The near-infrared light shielding film having such a configuration is preferably used due to its high near-infrared light shielding effect in a low-latitude zone near the equator where the illuminance of sunlight is high. However, in the mid-latitude to high-latitude winter season, there is a problem that incident light is uniformly shielded even when it is desired to capture sunlight as much as possible in the vehicle or in the room.

In order to solve the above-described problems, a method of applying a thermochromic material that controls the optical properties of near-infrared light shielding and transmission by temperature to the near-infrared light shielding film has been studied. A typical material is vanadium dioxide (hereinafter also referred to as “VO ₂ ”). It is known that vanadium dioxide causes a phase transition in a temperature range of around 68 ° C. and exhibits thermochromic properties.

  That is, the thermochromic film utilizing the characteristics of vanadium dioxide can shield near infrared light that causes heat at a high temperature and transmit near infrared light at a low temperature. . As a result, when the summertime is hot, near-infrared light is shielded to suppress the temperature rise in the room, and when the wintertime is cold, external light energy can be taken in.

  However, since the vanadium dioxide particles having thermochromic properties are easily oxidized, the particles prevent the water molecules and oxygen molecules involved in the oxidation reaction from coming into contact with the vanadium dioxide particle surface and causing the oxidation reaction. A method for improving the oxidation resistance by coating the surface with a specific substance has been studied.

  For example, Patent Document 1 discloses vanadium dioxide particles whose particle surface is coated with another amorphous metal oxide. Patent Document 2 discloses a method of linking an organically modified long chain molecular material to the surface of vanadium dioxide particles.

  Although each of these proposed methods certainly improves the chemical stability, as a result of further studies by the present inventors, a thermochromic response accompanied by a change in infrared transmittance even at the same phase transition temperature. It was found that sex became slow. These have a significant effect on the structural phase transition of vanadium dioxide particles caused by heat by chemically linking the surface of the minute vanadium dioxide particles with other amorphous metal oxides and organically modified long-chain molecular materials. The rate of change is slow, and it takes time to develop the heat shielding effect, and it is presumed that the thermochromic response is lowered.

  Therefore, development of vanadium dioxide-containing particles having resistance to oxidation or the like (storage stability) and excellent thermochromic responsiveness and a thermochromic film using the same has been desired.

International Publication No. 2015/161313 Special table 2015-513508 gazette

  The present invention has been made in view of the above-mentioned problems and situations, and the problem to be solved is thermochromic vanadium dioxide-containing particles having excellent storage stability, high thermochromic responsiveness, a production method thereof, and It is providing the thermochromic film using this, and its manufacturing method.

  As a result of studying the cause of the above-mentioned problem in order to solve the above-mentioned problems, the present inventor has vanadium dioxide particles in the core part and is composed of an organic compound having at least a hydroxy group for modifying the surface of the vanadium dioxide particles. By providing thermochromic vanadium dioxide-containing particles characterized by having a first shell layer and a second shell layer containing an amorphous metal oxide in this order, excellent storage stability and high thermo It has been found that thermochromic vanadium dioxide-containing particles having chromic response can be realized, and the present invention has been achieved.

  That is, the said subject of this invention is solved by the following means.

1. Thermochromic vanadium dioxide-containing particles having a core-shell structure,
Having vanadium dioxide particles in the core, and
A first shell layer made of an organic compound having at least a hydroxy group that modifies the surface of the vanadium dioxide particles;
A second shell layer containing an amorphous metal oxide;
In this order, thermochromic vanadium dioxide-containing particles.

  2. 2. The amorphous metal oxide contained in the second shell layer is at least one selected from silicon oxide, titanium oxide, zinc oxide, hafnium oxide, cerium oxide, and molybdenum oxide. Thermochromic vanadium dioxide-containing particles.

  3. The thermochromic vanadium dioxide-containing particles according to item 1 or 2, wherein the organic compound contained in the first shell layer has an amino group or a nitrogen-containing heterocyclic group together with a hydroxy group.

  4). The thermochromic vanadium dioxide according to any one of claims 1 to 3, further comprising a third shell layer containing a hydrophobic organic compound on the surface of the second shell layer. Containing particles.

  5. The hydrophobic organic compound contained in the third shell layer is a compound having a hydrophobic alkyl group or a hydrophobic aryl group and at least one group selected from silazane, silicon alkoxide, alcohol, aldehyde, and carboxylic acid. The thermochromic vanadium dioxide-containing particles according to item 4, characterized in that:

  6). The thermochromic vanadium dioxide-containing particles according to any one of items 1 to 5, further comprising a compound containing an element having an effect of adjusting a phase transition temperature.

7). A method for producing thermochromic vanadium dioxide-containing particles, which produces the thermochromic vanadium dioxide-containing particles according to any one of items 1 to 6,
As a first shell layer forming step, a step of forming a shell layer by adding and dispersing an organic compound having at least a hydroxy group to an aqueous dispersion containing vanadium dioxide particles as core particles;
A thermochromic vanadium dioxide characterized in that, as the second shell layer forming step, an amorphous metal oxide forming precursor, a step of adding an alkali and alcohol to form a shell layer having an amorphous metal oxide Production method of contained particles.

8). A method for producing thermochromic vanadium dioxide-containing particles, which produces the thermochromic vanadium dioxide-containing particles according to any one of items 4 to 6,
As a first shell layer forming step, a step of forming a shell layer by adding and dispersing an organic compound having at least a hydroxy group to an aqueous dispersion containing vanadium dioxide particles as core particles;
A step of forming an amorphous metal oxide forming precursor, an alkali and an alcohol to form a shell layer having an amorphous metal oxide as a second shell layer forming step, and a third shell layer forming step As a manufacturing method of the thermochromic vanadium dioxide containing particle | grains characterized by having any process of the following process (3-1) or (3-2) as.

Step (3-1): The aqueous medium of the aqueous dispersion containing the vanadium dioxide particles forming the second shell layer is replaced with an organic solvent not containing a hydroxy group by ultrafiltration, and then the hydrophobic having a silazane group Forming a third shell layer by surface modification with an organic compound,
Step (3-2): treatment with a hydrophobic organic compound having at least one group selected from silicon alkoxide, alcohol, aldehyde and carboxylic acid in the presence of high-temperature high-pressure water in a subcritical state, or a subcritical state A hydrophobic organic compound having at least one group selected from silicon alkoxide, alcohol, aldehyde and carboxylic acid in the presence of high-temperature high-pressure water in a supercritical state after pretreatment in the presence of high-temperature high-pressure water in Forming a third shell layer by surface modification.

  9. A thermochromic film comprising the thermochromic vanadium dioxide-containing particles according to any one of items 1 to 6.

  10. The thermochromic film according to item 9, further comprising a hydrophobic binder.

11. A method for producing a thermochromic film containing thermochromic vanadium dioxide-containing particles,
The vanadium dioxide-containing particles produced by the method for producing thermochromic vanadium dioxide-containing particles according to item 7 or 8, and at least a hydrophobic binder are mixed, and the mixture is applied and dried. A method for producing a thermochromic film.

  By the above means of the present invention, it is possible to provide thermochromic vanadium dioxide-containing particles having excellent storage stability and high thermochromic responsiveness, a method for producing the same, a thermochromic film using the same, and a method for producing the same. it can.

  The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

In the vanadium dioxide (VO ₂ ) -containing particles having thermochromic properties of the present invention, as a first form, the core part is composed of vanadium dioxide particles, and the core particle surface has a hydroxy group in an ion-bonded manner. After the first shell layer is formed by modification with an organic compound, it is coated with a second shell layer containing an amorphous metal oxide, so that the thermochromic response is fast and the storage stability is ensured. Vanadium (VO ₂ ) -containing particles could be obtained.

  As described above, since vanadium dioxide particles having thermochromic properties are easily oxidized, it is necessary to protect the surface of vanadium dioxide particles from water molecules and oxygen molecules involved in the oxidation reaction. As a first step, the first shell layer is formed by modifying the organic compound having a hydroxy group so as to include vanadium dioxide particles that are easily oxidized. Next, the storage shell and the thermochromic responsiveness can both be achieved by forming the second shell layer thereon with an amorphous metal oxide having excellent gas barrier properties.

  The thermochromic responsiveness as referred to in the present invention is a characteristic that can be obtained by the following method. One surface of the heat insulation space is made of glass, a thermometer is arranged at a distance of 10 mm from the glass surface in the heat insulation space, and sunlight or similar light energy is irradiated from the outside with a constant energy, and the temperature of the temperature sensor Is defined as the time required for the temperature to rise 1 ° C. Therefore, it can be determined that the longer this time is, the better the thermochromic response is, and the property that the temperature rise in the heat insulation space can be delayed in order to reduce the infrared light transmittance early.

In the thermochromic vanadium dioxide-containing particles of the present invention, as a further preferable second form, the thermochromic vanadium dioxide-containing particles of the first form are formed on the second shell layer containing an amorphous metal oxide. The reproducibility of thermochromic characteristics can be further improved by chemically bonding a hydrophobic organic compound to form the third shell layer. This is because the volume change of the thermochromic vanadium dioxide (VO ₂ ) -containing particles accompanying the phase transition also affects the second shell layer having an amorphous metal oxide, but the hydrophobic organic compound is bound to the outermost part. By forming the third shell layer, the third shell layer becomes a capping layer, the particle surface structure is homogenized, and the resistance to structural fracture caused by the particle surface can be improved even when subjected to many volume changes. As a result, it is speculated that the reproducibility of thermochromic characteristics has been improved.

Schematic sectional view showing an example of the structure of the core-shell type thermochromic vanadium dioxide-containing particles of the present invention Schematic flow chart showing an example of a solvent substitution treatment device (ultrafiltration device) used for production of thermochromic vanadium dioxide-containing particles Schematic configuration diagram showing an example of a flow reactor applicable to the production of thermochromic vanadium dioxide-containing particles of the present invention 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 the thermochromic film of the present invention having a near infrared light shielding layer

  The thermochromic vanadium dioxide-containing particles of the present invention have vanadium dioxide particles in the core, and a first shell layer that modifies the surface of the vanadium dioxide particles with an organic compound having at least a hydroxy group, and an amorphous A multilayer structure having a second shell layer containing a metal oxide in this order. This feature is a technical feature common to or corresponding to the claimed invention.

  As an embodiment of the present invention, silicon oxide, titanium oxide, zinc oxide, hafnium oxide, cerium oxide can be used as an amorphous metal oxide for forming the second shell layer from the viewpoint of more manifesting the intended effect of the present invention. And at least one selected from molybdenum oxide is preferable in that it can be formed by a sol-gel reaction and can stably form an amorphous metal oxide without using a high-temperature baking step.

  In addition, when the first shell layer uses an organic compound having an adsorption group such as an amino group or a nitrogen-containing heterocyclic group together with a hydroxy group, the adsorption performance on the surface of the vanadium dioxide particles is improved, and the hydroxy group present at the same time. The group functions to bond with the amorphous metal oxide constituting the second shell layer formed thereon. By setting it as such a structure, storage stability and thermochromic responsiveness can further be improved.

  Further, by forming a third shell layer containing a hydrophobic organic compound on the surface of the second shell layer, as described above, the third shell layer becomes a capping layer and the particle surface structure is uniform. Thus, even when subjected to a large number of volume changes, the structural fracture resistance due to the particle surface can be improved, and the reproducibility of thermochromic characteristics can be improved.

  Further, as the hydrophobic organic compound contained in the third shell layer, a compound having a hydrophobic alkyl group or a hydrophobic aryl group and at least one group selected from silazane, silicon alkoxide, alcohol, aldehyde, and carboxylic acid. The selection is preferable in that the repeatability of thermochromic characteristics can be improved.

  In addition, the inclusion of a compound containing an element that has an effect of adjusting the phase transition temperature, by adjusting and optimizing the phase transition temperature, both the load on the cooling equipment in summer and the load on the heating equipment in winter It is more preferable from the point that energy saving measures can be taken by reducing.

  In addition, the thermochromic film of the present invention contains the thermochromic vanadium dioxide-containing particles described above, and the inclusion of a hydrophobic binder improves compatibility with the vanadium dioxide particles, has low haze, and is thermochromic. This is preferable from the viewpoint that the responsiveness can be further improved.

  Moreover, in the manufacturing method of the thermochromic vanadium dioxide containing particle | grains comprised from the core particle / 1st shell layer / 2nd shell layer which is the 1st form of this invention, as a 1st shell layer formation process, a core particle As a step of forming a shell layer by adding and dispersing an organic compound having at least a hydroxy group to an aqueous dispersion containing vanadium dioxide particles as a second shell layer forming step, an amorphous metal oxide forming precursor and And a step of forming a shell layer having an amorphous metal oxide by adding an alkali and an alcohol.

  Moreover, in the manufacturing method of the thermochromic vanadium dioxide containing particle | grains comprised from the core particle / 1st shell layer / 2nd shell layer / 3rd shell layer which is the 2nd form of this invention, 1st shell layer formation is carried out. As a process, a shell layer is formed by adding and dispersing an organic compound having at least a hydroxy group in an aqueous dispersion containing vanadium dioxide particles as core particles, and an amorphous metal oxidation is performed as a second shell layer forming process. A vanadium dioxide particle having a step of forming a shell layer having an amorphous metal oxide by adding a product forming precursor, alkali and alcohol, and forming a second shell layer as a third shell layer forming step The aqueous medium containing the aqueous dispersion is substituted with an organic solvent containing no hydroxy group by ultrafiltration, and then has a silazane group A step of forming a third shell layer by surface modification with a hydrophobic organic compound, or hydrophobicity having at least one group selected from silicon alkoxide, alcohol, aldehyde and carboxylic acid in the presence of high-temperature high-pressure water in a subcritical state Selected from silicon alkoxides, alcohols, aldehydes, and carboxylic acids in the presence of supercritical high-temperature high-pressure water after pretreatment in the presence of high-temperature high-pressure water in a subcritical state. And manufacturing a vanadium dioxide-containing particle capable of exhibiting the object effect of the present invention, characterized by having a step of forming a third shell layer by surface modification with a hydrophobic organic compound having at least one group. Can do.

  In the present invention, the particles constituting the vanadium dioxide-containing particles are referred to as “vanadium dioxide particles”, and a structure in which a shell layer is formed on the surface of the vanadium dioxide particles to form the core-shell particles is “thermochromic vanadium dioxide-containing particles”. Referred to as “particles”. In the following description, the thermochromic vanadium dioxide-containing particles may be simply referred to as vanadium dioxide-containing particles or the vanadium dioxide-containing particles of the present invention.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, "-" shown in this invention i is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<Thermochromic vanadium dioxide-containing particles>
The thermochromic vanadium dioxide-containing particles of the present invention have a core-shell structure, have vanadium dioxide particles in the core, and are composed of an organic compound having at least a hydroxy group that modifies the surface of the vanadium dioxide particles. It has a shell layer and a second shell layer containing an amorphous metal oxide in this order.

  Hereinafter, the structure of the thermochromic vanadium dioxide-containing particles of the present invention, the materials used for the preparation of the thermochromic vanadium dioxide-containing particles, and details of the production method will be described.

[Structure of vanadium dioxide-containing particles]
The first form of the vanadium dioxide-containing particles of the present invention comprises a first shell layer comprising an organic compound having vanadium dioxide particles in the core portion and having at least a hydroxy group that modifies the surface of the vanadium dioxide particles; A multilayer structure having a second shell layer containing a metal oxide in this order, and as a second form, a structure having a third shell layer further containing a hydrophobic organic compound on the surface of the second shell layer It is.

  FIG. 1 is a schematic sectional view showing an example of the structure of the core-shell type thermochromic vanadium dioxide-containing particles of the present invention.

  FIG. 1 (a) shows the structure of the core-shell type vanadium dioxide-containing particles (1a) of the first embodiment of the present invention. The vanadium dioxide-containing particles (1a) are composed of vanadium dioxide particles. (2), the first shell layer (3) is formed of an organic compound having at least a hydroxy group on the outer periphery thereof, and the second shell layer (4) containing an amorphous metal oxide at the outermost portion. Is formed.

  FIG. 1 (b) shows the structure of the core / shell type vanadium dioxide-containing particles (1b) of the second embodiment of the present invention, and the vanadium dioxide-containing particles having the structure described in FIG. 1 (a). The structure which further formed the 3rd shell layer (5) containing a hydrophobic organic compound on the surface of the 2nd shell layer (4) of (1a) is shown.

[Constituent material of vanadium dioxide-containing particles]
(Vanadium dioxide particles: Core particles)
The vanadium dioxide particles constituting the core particles of the vanadium dioxide-containing particles of the present invention are not particularly limited as their crystal form, but from the viewpoint of efficiently expressing thermochromic properties (automatic light control), rutile type dioxide dioxide. It is particularly preferable to use vanadium particles (VO ₂ particles).

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 particles and secondary particles of vanadium dioxide particles in the optical functional layer described later in detail is preferably 200 nm or less, more preferably in the range of 1 to 180 nm, Preferably, it exists in the range of 5-100 nm.

  The number average particle size of the primary and secondary particles of vanadium dioxide containing particles having a core / shell structure is preferably 250 nm or less, more preferably in the range of 1 to 200 nm, and still more preferably 10 to 10 nm. Within the range of 150 nm.

  The average particle diameter of the vanadium dioxide particles can be determined by the following method. The particles are photographed at 10,000 to 100,000 times using a transmission electron microscope (TEM). The diameter of the photographed vanadium dioxide particles is measured to obtain an arithmetic average. At this time, it is preferable that the vanadium dioxide particles to be measured are in the range of 100 to 200 particles. In addition, when the said particle | grain is not perfect spherical shape, it calculates | requires as a diameter when the projected area of the said particle | grain is made into a circle equivalent diameter.

  In addition, the aspect ratio of the vanadium dioxide particles and the vanadium dioxide-containing particles is preferably in the range of 1.0 to 3.0.

  The vanadium dioxide particles constituting the core particles having such characteristics have a sufficiently small aspect ratio and an isotropic shape, and therefore have good dispersibility when added to a solution. In addition, since the single crystal has a sufficiently small particle size, it can exhibit better thermochromic properties than conventional fine particles.

<Elements that adjust the phase transition temperature>
In the vanadium dioxide-containing particles of the present invention, it is preferable to contain a compound containing an element having a phase transition temperature adjusting action, and in particular, the vanadium dioxide particles constituting the core particle contain an element having a phase transition temperature adjusting action. It is preferable to contain the compound to contain.

That is, in the vanadium dioxide particles constituting the core particle 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 ( At least one element selected from the group consisting of F) and phosphorus (P) may be included as a phase transition temperature regulator. 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. In addition, about 0.1-5.0 atomic% is sufficient for the total amount of such an additive with respect to the vanadium dioxide particle finally obtained with respect to a vanadium (V) atom.

  Further, the concentration of vanadium dioxide particles in the optical functional layer constituting the thermochromic film described later is not particularly limited, but is preferably in the range of 5 to 60% by mass with respect to the total mass of the optical functional layer. More preferably, it is in the range of 5 to 40% by mass, and further 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). Can refer to, for example, the production methods described in paragraph numbers (0011) and (0015) to (0018) of JP-A-2010-58984.

Among the above-mentioned aqueous synthesis methods, in the present invention, the hydrothermal synthesis method is applied, and an aqueous dispersion containing vanadium dioxide particles is prepared by the aqueous synthesis method, 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. By forming the optical functional layer using the coating liquid for forming the optical functional layer in this state, an optical functional layer in which the number average particle diameter of the primary particles and secondary particles of the vanadium dioxide-containing particles is 200 nm or less is formed. be able to. 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 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 exists in the range of 250-300 degreeC, More preferably, it exists in the range of 250-280 degreeC. 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. Moreover, it is preferable that the time of a hydrothermal reaction process exists in the range of 1 hour-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.

(First shell layer)
The first shell layer according to the present invention is formed on the surface of the vanadium dioxide particles described above with an organic compound having at least a hydroxy group that is ionically modified with the surface. The term “ionic bonding” as used herein refers to the property of adsorbing on the surface of vanadium dioxide particles with positive or negative charge attraction.

  The organic compound modified in an ionic bond according to the present invention is preferably a compound having an amino group or a nitrogen-containing heterocyclic group together with a hydroxy group. An amino group or a nitrogen-containing heterocyclic group expresses a high adsorbing ability as an adsorbing group on the surface of vanadium dioxide particles, and a hydroxy group is an amorphous metal oxide that is a constituent material of the second shell layer formed on the first shell layer It is a functional group that functions to bind to an object.

  The compound according to the present invention is preferably a compound having an amino group or a nitrogen-containing heterocyclic group together with a hydroxy group (—OH), and the compound is not particularly limited. It can be illustrated.

  In addition to the above compound, as a nitrogen-containing heterocyclic group together with a hydroxy group, for example, pyrrolidine, pyrrole, piperidine, pyridine, imidazole, pyrazole, oxazole, thiazole, imidazoline, pyrazine, morpholine, thiazine, indole, benzimidazole, etc. The group can be mentioned.

  As a method for forming the first shell layer according to the present invention, an aqueous dispersion containing vanadium dioxide particles as core particles, an organic compound having at least a hydroxy group, more preferably an amino group or a nitrogen-containing heterocycle together with a hydroxy group. A first shell layer can be formed on the surface of the vanadium dioxide particles by adding an organic compound having a group and performing a dispersion treatment for a predetermined time.

  A dispersion method applicable to the formation of the first shell layer is not particularly limited. For example, a mixing / dispersing method using a stirring type disperser, a mixing / dispersing method using a bead mill, a beadless mill, a ball mill, or a three-roll mixing. -A dispersion method, a mixing / dispersing method using a rotation / revolution mixer, and the like can be appropriately selected and applied.

(Second shell layer)
The second shell layer constituting the vanadium dioxide-containing particles of the present invention is characterized by containing an amorphous metal oxide.

  The term “amorphous” as used in the present invention means that when the formed second shell layer is subjected to XRD analysis (X-ray diffraction method), it is measured with little three-dimensional regularity as atoms and molecules constituting the solid. In the X-ray diffraction spectrum, only a halo pattern is observed, and it is defined as a layer that does not show a specific diffraction line peak indicating crystallinity.

  Examples of the XRD measurement apparatus used in the above measurement include X-ray diffractometers XRD-7000 and XRD-6100 manufactured by Shimadzu Corporation, X-ray diffractometers manufactured by Rigaku (XRD measurement apparatus RINT2200, RINT-TTR2, SWRD, etc.), etc. Can be mentioned.

  As a 2nd shell layer, the 2nd shell layer comprised from an amorphous metal oxide can be obtained by performing a hydrolysis and polycondensation in a liquid phase using a sol-gel reaction. The sol-gel reaction here is one of chemical operations for synthesizing ceramics and the like in a general sense by turning an alkoxide sol into a gel state by heating or the like.

Examples of the amorphous metal oxide applicable to the present invention include TiO ₂ , ITO, ZnO, Nb ₂ O ₅ , ZrO ₂ , CeO ₂ , Ta ₂ O ₅ , Ti ₃ O ₅ , Ti ₄ O ₇ , and Ti ₂ O. ₃ , TiO, SnO ₂ , La ₂ Ti ₂ O ₇ , IZO, AZO, GZO, ATO, ICO, Bi ₂ O ₃ , a-GIO, Ga ₂ O ₃ , GeO ₂ , SiO ₂ , Al ₂ O ₃ , HfO ₂ , SiO, MgO, Y ₂ O ₃ , WO ₃ , IGZO, In ₂ O _{3 and the} like. Among them, the second shell formed by silicon oxide (SiO ₂ ), titanium oxide (TiO ₂ ), zinc oxide (ZnO), hafnium oxide (HfO ₂ ), cerium oxide (CeO ₂ ), and molybdenum oxide (MoO ₂ ). The layer is preferable in that high transparency can be obtained.

As a method for forming the second shell layer according to the present invention, the second shell layer is formed on the first shell layer using a sol-gel method in a liquid phase system. For example, silicon oxide (SiO ₂ ) is used. When the sol-gel method is used, an alkoxide (silica precursor) such as TEOS (tetraethoxysilane) as an amorphous metal oxide formation precursor is hydrolyzed / reacted under basic conditions together with alkali and alcohol. By performing a condensation reaction, alcohol is eliminated and a second shell layer composed of an amorphous metal oxide is formed, whereby the vanadium dioxide-containing particles of the first form can be prepared.

  Further, the formation of the second shell layer can be performed under acidic conditions as required. However, in the case of forming a silica layer, in general, denser silica is obtained under strong basic conditions. easy.

(3rd shell layer)
In the vanadium dioxide-containing particles of the present invention, as a second form, forming a third shell layer containing a hydrophobic organic compound on the second shell layer described above provides high repetition resistance. This is a more preferable configuration.

  The third shell layer is formed of a hydrophobic organic compound. Furthermore, the hydrophobic organic compound is at least one selected from a hydrophobic alkyl group or a hydrophobic aryl group, silazane, silicon alkoxide, alcohol, aldehyde, and carboxylic acid. A compound having a seed group is preferable.

(1) Hydrophobic alkyl group Examples of the hydrophobic alkyl group include linear, branched, or unsaturated alkyl groups having 1 to 23 carbon atoms that may have an unsaturated group. Examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a pentadecyl group, a hexadecyl group, and an octadecyl group.

(2) Hydrophobic aryl group Examples of the hydrophobic aryl group include phenyl, tolyl, xylyl, naphthyl, and azulene groups.

(3) Silazane (silylating agent)
Specific examples of silazanes applicable to the present invention include trimethylsilyl chloride, hexamethyldisilazane, trimethylsilyltrifluoromethanesulfonate, triethylsilyl chloride, t-butyldimethylsilyl chloride, triisopropylsilyl chloride, 1,3-dichloro-1, Examples include 1,3,3-tetraisopropyldisiloxane, chloromethyltrimethylsilane, triethylsilane, t-butyldimethylsilane, trimethylsilylacetylene hesilamethyldisilane, allyltrimethylsilane, and trimethylvinylsilane. The said compound can also be obtained as a commercial item (for example, Shin-Etsu Silicone Co., Ltd., silylating agent).

(4) Silicon alkoxide Specific examples of the silicon alkoxide applicable to the present invention include the following compounds.

  Silanes include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxy. Examples thereof include silane, hexyltriethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, 1,6-bis (trimethoxysilyl) hexane, and trifluoropropyltrimethoxysilane. In addition, the said compound can also be obtained as a commercial item (for example, Shin-Etsu Silicone Co., Ltd., silane).

  Also, a silane coupling agent having an organic functional group and an alkoxy group in one molecule can be used. For example, vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, 3-acryloxypropylmethyl Dimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-triethoxysilyl-N- (1 , 3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and the like. In addition, the said compound can also be obtained as a commercial item (for example, Shin-Etsu Silicone Co., Ltd., a silane coupling agent).

(5) Alcohol Examples of the alcohol include linear or branched alcohols having 1 to 23 carbon atoms, such as methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, Examples include decanol, dodecanol, pentadecanol, octadecanol, icosanol, docosanol, and tricodanol.

(6) Aldehydes Examples of aldehydes include linear or branched aldehydes having 1 to 23 carbon atoms, such as methanal (formaldehyde), ethanal (acetaldehyde), propanal (propionaldehyde). ), Butanal, pentanal, hexanal, octanal, decanal, dodecanal, pentadecanal, octadecanal, icosanal, docosanal, tricodanal, acrolein, benzaldehyde, vanillin, glyoxal and the like.

(7) Carboxylic acid Examples of the carboxylic acid include saturated fatty acids, unsaturated fatty acids, aromatic carboxylic acids, and dicarboxylic acids.

  For example, saturated fatty acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, etc. it can.

  Examples of unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, and the like.

  Examples of the aromatic carboxylic acid include benzoic acid, phthalic acid, salicylic acid, gallic acid, and cinnamic acid.

  Examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid and the like.

  As an example of the method for forming the third shell layer composed of the hydrophobic organic compound according to the present invention, vanadium dioxide particles on which the second shell layer is formed have a hydroxy group by ultrafiltration. A method of forming a third shell layer on the outermost layer by replacing the dispersion medium with a non-organic solvent and then treating with a hydrophobic organic compound, for example, a hydrophobic compound having a silazane group, can be mentioned.

  In addition, as a second method, at least one group selected from silicon alkoxide, alcohol, aldehyde, and carboxylic acid in the presence of high-temperature high-pressure water in a subcritical state is applied to the vanadium dioxide particles forming the second shell layer. Or a pretreatment in the presence of high-temperature high-pressure water in a subcritical state, and then in the presence of high-temperature high-pressure water in a supercritical state, silicon alkoxide, alcohol, aldehyde and carvone Examples thereof include a method of forming the third shell layer by treating with a hydrophobic organic compound having at least one group selected from acids.

(Method for producing thermochromic vanadium dioxide-containing particles)
As a method for producing thermochromic vanadium dioxide-containing particles, for the particles of the first embodiment shown in FIG. 1A, after preparing vanadium dioxide particles that are core particles by the method described above, According to a conventional method, the material for forming the first shell layer and the constituent material for the second shell layer are sequentially added to the vanadium dioxide particles in an aqueous system, and each is coated by the sol-gel method as described above. Containing particles can be prepared.

  That is, as a first shell layer forming step, a step of forming a shell layer by adding and dispersing an organic compound having at least a hydroxy group in an aqueous dispersion containing vanadium dioxide particles as core particles, and a second shell layer forming step As a process, it has the process of adding an amorphous metal oxide formation precursor, an alkali, and alcohol, and forming a shell layer which has an amorphous metal oxide.

  On the other hand, the method for producing vanadium dioxide-containing particles of the present invention has technical characteristics in the method of forming the third shell layer in the vanadium dioxide-containing particles having the configuration shown in FIG. Details of the method of forming the third shell layer will be described.

  The vanadium dioxide-containing particles of the present invention are produced according to the following two methods.

(1) First production method of vanadium dioxide-containing particles The first production method is to add an organic compound having at least a hydroxy group to an aqueous dispersion containing vanadium dioxide particles synthesized by a hydrothermal method or the like as core particles. After forming the first shell layer by dispersion, an amorphous metal oxide forming precursor, alkali and alcohol are added to form a second shell layer having an amorphous metal oxide, and then by ultrafiltration Substitution with an organic solvent that does not contain a hydroxy group, and then, as step (3-1), treatment with a hydrophobic organic compound having a silazane group to form a third shell layer, containing vanadium dioxide having thermochromic properties A method characterized by producing particles.

  That is, as a method for forming the third shell layer composed of the hydrophobic organic compound, the aqueous dispersion contains the vanadium dioxide particles formed up to the second shell layer by ultrafiltration. In this method, the third shell layer is formed by replacing water with an organic solvent containing no hydroxy group and then treating with a hydrophobic organic compound having a silazane group.

  A hydrophobic compound (silylating agent) having a silazane group is a property that readily reacts with a compound containing a hydroxy group such as water or alcohol and easily decomposes, and before the formation of the third shell layer, the hydroxy compound Replace the dispersion medium with an organic solvent that does not contain groups.

  The organic solvent applied by the above method is preferably a solvent in which the vanadium dioxide particles formed up to the second shell layer do not aggregate and settle and are miscible with water and alcohol. Specifically, acetonitrile, PGMAc (propylene glycol monomethyl ether acetate), ethylamine, 2-pyrrolidone, NMP (N-methyl-2-pyrrolidone), pyridine, dioxolane, 2-methyldioxolane, ethylene carbonate, γ-butyrolactone, THF (Tetrahydrofuran), morpholine, DMF (dimethylformamide), DMSO (dimethylsulfoxide) and the like.

Next, a specific example of a manufacturing method using an ultrafiltration method applicable to the first manufacturing method will be described with reference to the drawings.
A specific solvent replacement process will be described with reference to the drawings.

  FIG. 2 is a schematic flow diagram showing an example of a solvent replacement processing device (ultrafiltration device) used for production of vanadium dioxide-containing particles.

  The solvent replacement processing apparatus (50) shown in FIG. 2 includes a preparation kettle (51) for storing a mixed solution (52) containing vanadium dioxide particles formed up to the second shell layer, and a dilution solvent (58). The stored solvent stock kettle (57), the solvent supply line (59) for adding the solvent (58) to the adjustment kettle (51), and the circulation line (53) for circulating the preparation kettle (51) by the circulation pump (54) ), An ultrafiltration part (55) is arranged as a concentration means in the path of the circulation line (53).

  Hereinafter, the flow of the ultrafiltration process will be described following the procedure.

<Process (I)>
In the preparation kettle (51), an aqueous dispersion containing vanadium dioxide particles formed up to the second shell layer prepared as described above is stored as a mixed solution (52) and circulated using a circulation pump (54). In the ultrafiltration unit (55), the water in the mixed solution is discharged from the discharge port (56) and concentrated to a predetermined concentration. As a standard of concentration, it concentrates to 20 volume% with respect to the initial volume. It is preferable to avoid excessive concentration beyond this because particle aggregation occurs as the particle density increases. In this concentration operation, it is important not to dry the mixed solution.

<Process (II)>
Next, 80% by mass of the solvent (58) is added to the mixed solution (52) concentrated to 20% by volume from the solvent stock kettle (57) via the solvent supply line (59), and sufficiently stirred. Mixing is performed to prepare a mixed solution (52) with a primary solvent substitution.

<Process (III)>
Next, in the same manner as in the above step (I), the medium (water + solvent) in the mixed solution (52) is discharged out of the system by the ultrafiltration unit (55) while circulating by the circulation pump (54) ( 56), and the second concentration is performed again to a concentration of 20% by volume.

<Process (IV)>
Next, in the same manner as in the above step (II), 80% by mass of the solvent (58) is added to the concentrated mixed solution (52) from the solvent stock kettle (57) via the solvent supply line (59). The mixture is sufficiently stirred and mixed to move the vanadium dioxide particles from the aqueous phase to the organic phase, and the organic phase is extracted.

<Process (V)>
Finally, the concentration and solvent dilution operations in step (I) and step (II) are preferably repeated twice or more to adjust the water content to a range of 0.1 to 5.0% by mass. A solvent dispersion containing vanadium particles is prepared, and this is treated with a hydrophobic organic compound having a silazane group to form a third shell layer.

  Examples of the ultrafiltration method used in the solvent replacement treatment include, for example, No. 1 of Research Disclosure (Research Disclosure). 10208 (1972), no. 13122 (1975) and no. 16351 (1977) and the like can be referred to.

  The pressure difference and flow rate that are important as operating conditions can be set with reference to the characteristic curve described in Haruhiko Oya's “Membrane Utilization Technology Handbook”, Koshobo Publishing (1978), p275.

  For ultrafiltration membranes, organic membranes, flat plate types, spiral types, cylindrical types, hollow fiber types, hollow fiber types, etc., already incorporated as modules, are available at Asahi Kasei Corporation, Daicel Chemical Co., Ltd. ( Although commercially available from Toray Industries, Inc. and Nitto Denko Corporation, etc., ceramic films such as NGK Co., Ltd. and Noritake Corporation are preferred as the solvent-resistant film.

Specifically, for example, Vivaflow 50 (effective filtration area 50 cm ² , fractional molecular weight 5000) manufactured by Sartorius steady is used as a filtration membrane, and ultrafiltration is performed at a flow rate of 300 ml / min (minutes), a hydraulic pressure of 100 kPa, and room temperature. Examples thereof include an ultrafiltration device having a filtration membrane made of polyethersulfone and a molecular weight cut off of 300,000 (Pericon 2 cassette, manufactured by Nihon Millipore Corporation).

(2) Second Production Method for Vanadium Dioxide-Containing Particles The second production method comprises adding an organic compound having at least a hydroxy group to an aqueous dispersion containing vanadium dioxide particles as core particles, and dispersing the first shell. After forming the layer, an amorphous metal oxide forming precursor, alkali and alcohol are added to form a second shell layer having an amorphous metal oxide, and then as shown in step (3-2), Treatment with a hydrophobic organic compound having at least one group selected from silicon alkoxide, alcohol, aldehyde and carboxylic acid in the presence of high-temperature high-pressure water in a subcritical state, or presence of high-temperature high-pressure water in a subcritical state After pre-treatment, silicon alkoxide, alcohol, aldehyde and carbohydrate in the presence of high-temperature high-pressure water in a supercritical state. It is a method characterized by producing vanadium dioxide-containing particles by forming a third shell layer by treatment with a hydrophobic organic compound having at least one group selected from acid.

  Hereinafter, details of the second manufacturing method will be described.

  In the second method for producing vanadium dioxide-containing particles of the present invention, the vanadium dioxide particles formed up to the second shell layer are formed from silicon alkoxide, alcohol, aldehyde, and carboxylic acid under conditions where water at high temperature and high pressure exists. This is a method for obtaining vanadium dioxide-containing particles having a surface formed with a third shell layer of a hydrophobic organic compound by reacting with a hydrophobic organic compound having at least one selected group. You may include the process which activates the surface of the vanadium dioxide particle formed to 2 shell layers, or the pretreatment in the presence of the water in a subcritical state for the vanadium dioxide particles formed to the 2nd shell layer.

  In the second production method of the present invention, the high-temperature and high-pressure water is high-temperature and high-pressure water in a subcritical or supercritical state, that is, sub-critical water (sub-CW), or supercritical. It is water (super-critical water: SCW). Since the critical temperature of water is 374.2 ° C. and the critical pressure of water is 22.12 MPa, the reaction temperature and reaction pressure can be selected with reference to this. Specifically, subcritical water refers to water that is slightly lower in temperature and / or pressure than the supercritical point of water. For example, in terms of temperature, a critical temperature 374 from a region of 150 ° C. or higher. A region where the temperature is lower than the critical temperature of water and the pressure is a critical pressure of 22 MPa or higher is exemplified.

  In one specific embodiment, the pressure of the raw material mixture containing vanadium dioxide particles formed up to the second shell layer supplied to the reaction system (for example, the reactor (reactor) in the constant temperature zone) is set to the criticality of water. Vanadium dioxide particles formed to a second shell layer heated to a predetermined reaction temperature such that the pressure was 22.12 MPa or higher (for example, 30 MPa or 35 MPa), and the temperature was approximately 150 ° C. The raw material mixture solution is supplied to a reactor (reaction under subcritical water) set to a reaction temperature of 250 ° C., or a reactor (supercritical water) set to a reaction temperature of 390 ° C. In the sub-critical or supercritical state, which is the reaction field, can be achieved under the condition that high-temperature and high-pressure water exists.

  A typical subcritical water region has a critical pressure of 22 MPa or higher, and a region of 180 ° C. or higher to a critical temperature of 374 ° C., or a temperature of 200 ° C. or higher to a critical temperature of 374 ° C. Or a region from a temperature of 250 ° C. or higher to a critical temperature of 374 ° C., a region of 300 ° C. or higher to a critical temperature of 374 ° C., or the like. Of course, the subcritical water region has a pressure range of 10.0 MPa or higher to a critical pressure of 22 MPa, or a pressure range of 15.0 MPa or higher to a critical pressure of 22 MPa, or a pressure of 18.0 MPa or higher to a critical pressure of 22 MPa. A region or a region from a pressure of 20.0 MPa or more to a critical pressure of 22 MPa may also be included.

  In the pretreatment of the vanadium dioxide particles formed up to the second shell layer used in the present invention, the treatment temperature is, for example, 150 to 374 ° C., preferably 200 to 374 ° C., more preferably 230 to 374 ° C. Preferably it is 280-360 degreeC.

  Moreover, as the processing pressure, it is 15-50 MPa, for example, Preferably it is 18-45 MPa, More preferably, it is 20-40 MPa, More preferably, it is 20-35 MPa. In a typical case, the processing temperature is 280 to 320 ° C., and the processing pressure is 20 to 25 MPa.

  In the formation reaction of the third shell layer on the vanadium dioxide particles formed up to the second shell layer of the present invention, the reaction temperature is, for example, 375 to 500 ° C., preferably 375 to 450 ° C., more preferably 375-420 ° C, more preferably 375-400 ° C. In some cases, for example, 375-395 ° C, preferably 375-390 ° C, more preferably 375-385 ° C, or 375-380 ° C, The reaction pressure is, for example, 20 to 50 MPa, preferably 21 to 45 MPa, more preferably 22 to 40 MPa, and further preferably 22 to 35 MPa.

  The reaction can be carried out by a batch type (batch type) or a semi-batch type (semi-batch type), but a flow type reactor (flow type reactor) such as a pressure resistant tube type or tank type is preferably used. A continuous method can be used, and in particular, a continuous method using a tubular reactor can be suitably used.

  The configuration of a typical flow reactor applicable to the second production method of the present invention will be described with reference to the drawings.

  FIG. 3 is a schematic configuration diagram showing an example of a flow reactor applicable to the second method for producing vanadium dioxide-containing particles of the present invention.

  As shown in FIG. 3, the flow-type reactor (100) is preheated with preheated water (102, also referred to as high-pressure raw material water) such as distilled water, deionized water, or pure water, and then stored. A water supply path (105) for supplying water to be subcritical water or supercritical water from a preheated water tank (hot water supply source tank (deionized hot water supply tank)), and vanadium dioxide particles formed to the second shell layer The high-pressure raw material liquid (101) including the raw material supply path (107) is provided, and the high-pressure raw material liquid (101) is pretreated by passing through the heater section (H), and then the water supply path. Join (105). Next, the mixed liquid of the heated high-pressure raw material liquid (101) and the high-temperature high-pressure water (102) is a hydrophobic organic compound solution supplied from the hydrophobic organic compound supply path (106) in the shell forming part (M). (103) joins, and a third shell layer made of a hydrophobic organic compound is formed on the second shell layer of the vanadium dioxide particles under high temperature and high pressure.

  The hydrophobic organic compound solution (103) is composed of a hydrophobic compound having the characteristics of the present invention and an organic solvent that dissolves the hydrophobic compound, as long as the organic solvent dissolves the hydrophobic compound. Although there is no particular limitation, for example, alcohols, ketones, esters, and aromatics are preferable. Specifically, methanol, ethanol, propanol, isopropanol, butanol, acetone, methyl ethyl ketone (abbreviation: MEK), methyl isobutyl ketone (abbreviation: MIBK), cyclohexanone, cyclopentanone, ethyl acetate (abbreviation: EA), butyl acetate ( Abbreviations: BA), toluene, xylene and the like.

  In the water supply path (105), the raw material supply path (107), and the hydrophobic organic compound supply path (106), a pressurizing means for pressurizing water to a subcritical pressure or a critical pressure or higher, that is, a high pressure A pump (P) and heating means (H) for heating the high-pressure water or the like to a predetermined temperature equal to or higher than the subcritical temperature or higher than the critical temperature, that is, a heating furnace (heater) are sequentially provided.

  The mixture obtained by mixing at the junction is introduced into a reactor disposed in the isothermal zone of the shell forming part (M). The reactor is covered with a molten salt bath jacket or the like, has a constant temperature zone, and is adjusted to have a predetermined reaction temperature. The temperature can be monitored by, for example, a temperature sensor equipped with a thermocouple. Next, the generated core-shell type vanadium dioxide-containing particles (104) pass through the cooling part (C, water cooling jacket), the recovery part (G), the pressure regulating valve, for example, the back pressure valve (V), and vanadium dioxide. Move to the contained particle storage tank.

  The core-shell type vanadium dioxide-containing particles formed up to the third shell layer according to the present invention are usually cooled to room temperature after the reaction. As a method for separating the prepared vanadium dioxide-containing particles from the reaction mixture, a known method may be used, or a physical method or a chemical method may be used. Since the surface of the vanadium dioxide-containing particles obtained by the present invention is modified with a hydrophobic organic compound, various physical properties can be imparted by the modifying group, and they are isolated by utilizing the properties of the modifying group. You can also.

  The obtained vanadium dioxide-containing particles can be appropriately subjected to filtration treatment to remove agglomerates, and are further subjected to centrifugal treatment, decantation treatment, washing treatment with distilled water, pure water, and the like. The metal oxide particles can be washed by using a dilute alkaline aqueous solution such as a dilute KOH aqueous solution, repeating the redispersion treatment and the centrifugal separation treatment, or performing ultrafiltration. The metal oxide particles of the present invention thus obtained can be obtained in the form of a powder by drying by a known method, for example, freeze-drying.

《Thermochromic film》
The thermochromic film of the present invention is characterized by containing at least the thermochromic vanadium dioxide-containing particles of the present invention, and preferably further contains a hydrophobic binder as a binder resin.

[Configuration of thermochromic film]
The typical structural example of the thermochromic film of this invention is demonstrated with reference to figures.

  FIG. 4 is an example of a basic configuration of the thermochromic film of the present invention, and is a schematic cross-sectional view showing a configuration in which an optical functional layer is formed on a transparent substrate.

The thermochromic film (11) shown in FIG. 4 has the structure which formed the optical function layer (13) on the transparent base material (12). The optical functional layer (13) is present in a state where the core-shell type thermochromic vanadium dioxide-containing particles of the present invention are dispersed in the hydrophobic binder (B1). The vanadium dioxide-containing particles include primary particles (VO _S ) of vanadium dioxide-containing particles in which vanadium dioxide-containing particles exist independently, and aggregates (also referred to as aggregates) of two or more vanadium dioxide-containing particles. Secondary particles (VO _M ) of vanadium dioxide-containing particles are present. In the present invention, an aggregate of two or more vanadium dioxide-containing 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 diameter of all the primary particles (VO _S ) and secondary particles (VO _M ) of the vanadium dioxide-containing particles in the optical functional layer (13) is preferably 200 nm or less.

  In the present invention, the average particle size of the vanadium dioxide-containing particles in the optical functional layer can be determined according to the following method.

First, the side surface of the optical functional layer (13) constituting the thermochromic film (11) 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 diameter of all the vanadium dioxide-containing particles present in a certain region of the photographed cross section is measured. At this time, it is preferable that the vanadium dioxide containing particle | grains to measure are in the range of 100-200 pieces. As shown in FIG. 4, the photographed particles include primary particles that are single particles and secondary particles that are aggregates of two or more particles. Primary particles (VO _S ) of vanadium dioxide-containing particles. The particle diameter of each particle is measured by measuring the diameter of each independent particle. If it is not spherical, the projected area of the particle is converted into a circle, and the diameter is taken as the particle diameter. On the other hand, for vanadium dioxide-containing particles 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 diameter.

  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 to obtain the whole number-average diameter, which is referred to in the present invention as the number-average particle size (nm). It was.

  In the thermochromic film of the present invention, in addition to the optical functional layer, 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.

  Another preferred embodiment of the thermochromic film of the present invention is a hybrid configuration in which the optical functional layer also functions as a resin base material.

FIG. 5 is a schematic sectional view showing another example of the basic configuration of the thermochromic film (11) of the present invention. As shown in FIG. 4, the transparent base material (12) and the optical functional layer (13) are composed of the hybrid optical functional layer (12 + 13) which is an aspect composed of the same layer, and constitute the transparent base material. The primary particles (VO _S ) of the vanadium dioxide-containing particles in which the hydrophobic binder (B2) is used as the polymer and the vanadium dioxide-containing particles are independently present in the hydrophobic binder (B2); The secondary functional particle (VO _M ) of one or more vanadium dioxide-containing particles is dispersed to form an optical functional layer having a single layer and also having a transparent substrate function.

  FIG. 6 shows a thermochromic film (11) having a configuration shown in FIG. 4 and having a near infrared light shielding layer (14) together with an optical functional layer (13) on a transparent substrate (12). It is a schematic sectional drawing which shows layer arrangement | positioning.

  The thermochromic film (11) shown in (a) of FIG. 6 is arranged in the order of the optical functional layer (13), the near infrared light shielding layer (14), and the transparent substrate (12) from the light incident side (L). It is the structure which is done.

  In the thermochromic film (11) shown in FIG. 6 (b), the optical functional layer (13) according to the present invention is disposed between the transparent substrate (12) and the near infrared light shielding layer (14). FIG. 6 (c) shows an example, in which a near infrared light shielding layer (14) is disposed on the light incident side (L) of the transparent substrate (12), and this is disposed on the back side of the transparent substrate (12). It is the example which has arrange | positioned the optical function layer (13) based on invention.

  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, Especially preferably, it exists in the range of 40-300 micrometers.

  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.

[Component materials of thermochromic film]
The thermochromic film of the present invention has vanadium dioxide-containing particles, an optical functional layer containing a binder resin, and a near-infrared light shielding layer having a function of shielding at least a part within a light wavelength range of 700 to 1000 nm. Is a preferable configuration.

  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 mainly contains the vanadium dioxide-containing particles of the present invention and a binder resin. Although there is no restriction | limiting in particular as a density | concentration of the vanadium dioxide containing particle | grains in an optical function layer, Generally it is preferable to exist in the range of 5-60 mass% with respect to the optical function layer total mass, More preferably, it is 5-40 mass%. And more preferably in the range of 5 to 30% by mass.

  In the thermochromic film of the present invention, the primary particle number ratio of the vanadium dioxide-containing particles in the optical functional layer is preferably 30% by number or more of the total number of primary particles and secondary particles, and more preferably. Is 50% by number or more, and 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. The measuring method is the same as the method for measuring the average particle size of the vanadium dioxide-containing particles.

<Hydrophilic binder>
In the thermochromic film of the present invention, a hydrophilic binder can be applied as a binder for holding vanadium dioxide-containing particles.

  The hydrophilic binder referred to in the present invention is not particularly limited as long as it is a resin having a dissolution amount of 1.0 g or more at a liquid temperature of 25 ° C. with respect to 100 g of water.

  As the hydrophilic binder applied to the present invention, it is preferable to use a water-soluble polymer. Examples of the hydrophilic polymer applicable to the present invention include polyvinyl alcohol, polyethyleneimine, gelatin (for example, a hydrophilic polymer typified by gelatin described in JP-A-2006-343391), starch, guar gum, and alginate. , Methyl cellulose, ethyl cellulose, hydroxyalkyl cellulose, carboxyalkyl cellulose, poly (meth) acrylamide, polyethyleneimine, polyethylene glycol, polyalkylene oxide, polyvinylpyrrolidone (PVP), polyvinyl methyl ether, carboxyvinyl polymer, poly (meth) acrylic acid, Sodium poly (meth) acrylate, naphthalene sulfonic acid condensate, proteins such as albumin and casein, sodium alginate, dextrin, dextran Such as sugar derivatives such as dextran sulfate and the like.

<Hydrophobic binder>
In the thermochromic film of the present invention, it is particularly preferable to apply a hydrophobic binder as a binder for holding vanadium dioxide-containing 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 olefin-based polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene), acrylate-based copolymers; Halogen-containing polymers such as vinyl and chlorinated vinyl resins; polystyrene-based 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; Ether ketone; Polysulfone; Polyethersulfone; Polyoxybenzylene; Polyamideimide; ABS resin (acrylonitrile-butadiene-styrene resin) and 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 uses a monomer of a hydrophobic binder and is polymerized in a curing process 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-methylol acrylamide, diacetone acrylamide, 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.

  Various known cationic polymerizable monomers can be used as the cationic polymerizable compound. 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 the light source of the active energy ray, 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 amount 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 resin Polymethylpentene, polyetherketone, polyimide, polyethersulfone (abbreviation: PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic and polyarylates And cyclone resins such as Arton (trade name, manufactured by JSR) and Apel (trade name, manufactured by Mitsui Chemicals).

  Further, the solvent is not particularly limited. For example, 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 function layer>
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 and the like, an anion, Various surfactants of 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 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 optical functional layer. It is preferable that 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 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. The constituent elements and forming methods described in JP-A-2014-089347 and the like can be referred to.

[Method for producing thermochromic film]
(Manufacturing method 1: Aqueous formation method)
As a manufacturing method of the thermochromic film of this invention, it is the method of forming by using the thermochromic vanadium dioxide containing particle | grains of this invention, and a hydrophilic binder, and forming an optical functional layer with 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.

  Moreover, when forming a hybrid optical functional layer that also serves as a resin base as shown in FIG. 5, a solution casting method can be applied. Solutions described in JP067074, JP2013-123868, JP2013-202979, JP2014-066958, JP2014-095729, JP2014-159082, etc. It can be formed according to a cast film forming method.

(Production method 2: Organic solvent system formation method 1)
In the present invention, the thermochromic vanadium dioxide-containing particles of the present invention are mixed in an organic solvent to prepare a non-aqueous dispersion, and then a hydrophobic binder is further added, followed by coating and drying to form an optical functional layer. It is also preferable 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.

(Production method 3: Organic solvent system formation method 2)
As another method for producing a thermochromic film using an organic solvent, first, vanadium dioxide particles were dispersed without drying an aqueous dispersion obtained by dispersing vanadium dioxide-containing particles obtained by an aqueous synthesis method. An organic solvent is added to the aqueous dispersion, the vanadium dioxide-containing particles are moved from the aqueous phase to the organic phase, and the organic phase is separated and extracted. And the method of forming an optical functional layer by mixing a hydrophobic binder with an organic phase, applying and drying, and cleaning the thermochromic film is also preferable. As a method for transferring the vanadium dioxide-containing particles from the aqueous phase to the organic phase, a general liquid separation operation is performed.

《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.

  EXAMPLES 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-containing particles 1)
0.433 g of ammonium vanadate (NH ₄ VO ₃ , manufactured by Wako Pure Chemical Industries, special grade) is 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.). A 5% by mass aqueous solution of (special grade) was slowly added dropwise to prepare a solution (A) having a pH value of 9.2 at 23 ° C. The prepared solution (A) is placed in a commercially available autoclave for hydrothermal reaction treatment (HU-25 type, manufactured by Sanai Kagaku Co., which has a 25 mL capacity Teflon (registered trademark) inner cylinder in a SUS body), and 100 Hydrothermal reaction treatment was performed at 270 ° C. for 8 hours and then at 270 ° C. for 24 hours to prepare an aqueous dispersion containing vanadium dioxide particles (I) as core particles.

Next, 50 ml of ethanol was added to 10 g of the aqueous dispersion containing vanadium dioxide particles (I), the pH was adjusted to 11.0 with 28% aqueous ammonia, and tetraethoxysilane (abbreviation: abbreviated as: TEOS) is added and maintained at 25 ° C. for 4 hours to form an amorphous metal oxide layer (second shell layer) composed of SiO ₂ as a shell layer on the surface of the vanadium dioxide particles (I). Then, core-shell type vanadium dioxide-containing particles 1 were prepared and dispersed so that the vanadium dioxide-containing particles 1 had a concentration of 3% by mass.

(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-containing particle dispersion 1 128 mass parts 3 mass% boric acid aqueous solution 10 mass parts 5 mass% hydrophilic binder resin S1 aqueous solution (PVA105, manufactured by Kuraray Co., Ltd.) 60 mass parts (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, and then dried by blowing hot air at 110 ° C. for 2 minutes to form an optical functional layer, thereby producing a thermochromic film 101 having the configuration shown in FIG. .

[Preparation of thermochromic film 102: aqueous]
In producing the thermochromic film 101, a thermochromic film 102 was produced in the same manner except that the vanadium dioxide-containing particles 2 prepared by the following method were used in place of the vanadium dioxide-containing particles 1.

(Preparation of vanadium dioxide-containing particles 2)
0.2 g of compound A14 as an organic compound having a hydroxy group was added to 10 g of an aqueous dispersion containing vanadium dioxide particles (I), which are core particles used in the preparation of the vanadium dioxide-containing particles 1, and homomixer (Primix Co., Ltd.) Using a company-made TK homomixer Mark II), the stirring blades were rotated at a peripheral speed of 7.85 m / sec and dispersed by stirring to form a first shell layer. Next, 50 ml of ethanol was added, the pH was adjusted to 11.0 with 28% ammonia water, 1.5 g of tetraethoxysilane (abbreviation: TEOS) was added under strong stirring, and maintained at 25 ° C. for 4 hours. Then, an amorphous metal oxide layer composed of SiO ₂ is formed as the second shell layer on the first shell layer of the vanadium dioxide particles (I), and the core-shell type vanadium dioxide-containing particles 2 are formed. The vanadium dioxide-containing particles 2 were prepared and dispersed so as to have a concentration of 3% by mass.

[Preparation of thermochromic film 103: aqueous]
In the preparation of the vanadium dioxide-containing particles 2 for producing the thermochromic film 102, the same preparation was performed except that instead of the compound A, the compound A1 having a hydroxy group and an amino group was used as the first shell layer forming material. A thermochromic film 103 was produced in the same manner except that the vanadium dioxide-containing particles 3 were used.

[Preparation of thermochromic films 104 to 106: aqueous]
In the preparation of the vanadium dioxide-containing particles 3 for the production of the thermochromic film 103, the preparation was performed in the same manner except that the formation material of the first shell layer was changed to the compound A2, the compound A4, and the compound A8, respectively, instead of the compound A1. Thermochromic films 104 to 106 were produced in the same manner except that the vanadium dioxide-containing particles 4 to 6 were used.

[Preparation of thermochromic film 107: aqueous]
In the preparation of the vanadium dioxide-containing particles 3 used for the production of the thermochromic film 103, the vanadium dioxide-containing particles 7 prepared in the same manner except that the forming method of the second shell layer was changed to the following forming method were used. A thermochromic film 107 was produced in the same manner except for the above.

(Formation of second shell layer)
To 10 g of the dispersion containing the vanadium dioxide particles formed up to the first shell layer, 50 ml of ethanol was added, the pH was adjusted to 3.0 with 1 mol / L nitric acid (HNO ₃ ), and the titanium tetraisosodium was stirred vigorously. Propoxide (Ti [OCH (CH ₃ ) ₂ ] ₄ ) was added and reacted at 80 ° C. for 6 hours to form a second shell layer composed of TiO ₂ .

[Preparation of thermochromic film 108: aqueous]
Using the dispersion containing the vanadium dioxide-containing particles 3 described in the thermochromic film 103, the dispersion is mixed with compound B1 (hexyltriethoxysilane, KBE-3063, manufactured by Shin-Etsu Silicone) and ethanol as a hydrophobic organic compound. The mixture was added and reacted at 80 ° C. for 2 hours to form a third shell layer composed of a hydrophobic organic compound on the second shell layer.

  Next, after centrifugal sedimentation and washing with pure water, pure water and sodium dodecylbenzenesulfonate were added, and a stirring blade was 7.85 m using a homomixer (Primix Co., Ltd., TK homomixer Mark II). A dispersion liquid was prepared by rotating at a peripheral speed of / sec and stirring to disperse the vanadium dioxide-containing particles 8 at a concentration of 3% by mass.

  In producing the thermochromic film 103, a thermochromic film 108 was produced in the same manner except that the vanadium dioxide-containing particles 8 prepared above were used instead of the vanadium dioxide-containing particles 3.

[Production of Thermochromic Film 109: Hydrophobic]
Using the dispersion containing the vanadium dioxide-containing particles 3 described in the thermochromic film 103, compound B1 (hexyltriethoxysilane, KBE-3063, manufactured by Shin-Etsu Polymer Co., Ltd.) and ethanol are used as the hydrophobic organic compound in the dispersion. The mixture was added and reacted at 80 ° C. for 2 hours to form a third shell layer composed of a hydrophobic organic compound on the second shell layer.

  Next, after centrifugal sedimentation and washing with ethanol, methyl ethyl ketone was added, and the stirring blade was rotated at a peripheral speed of 7.85 m / sec using a homomixer (Primix Co., Ltd., TK homomixer Mark II). Then, a dispersion was prepared in which the vanadium dioxide-containing particles 9 were dispersed so as to have a concentration of 3% by mass.

  In the production of the thermochromic film 103, a thermochromic film 109 was produced in the same manner except that the coating solution for forming an optical functional layer having the following configuration was used.

(Preparation of coating solution for optical functional layer formation)
3% by mass of vanadium dioxide-containing particle dispersion 9 128 parts by mass 5% by mass of hydrophobic binder resin O1 (Byron 200, manufactured by Toyobo Co., Ltd.) 65 parts by mass of methyl ethyl ketone solution [Production of thermochromic films 110 to 112: hydrophobic system]
In the preparation of the vanadium dioxide-containing particles 9 for producing the thermochromic film 109, the same preparation was performed except that instead of the compound A1, the compound A1 was replaced with the compound A2, and the compound A8 was used instead of the compound A1. Thermochromic films 110 to 112 were produced in the same manner except that the vanadium dioxide containing particles 10 to 12 were used.

[Production of Thermochromic Film 113: Hydrophobic]
Using the dispersion liquid containing the vanadium dioxide-containing particles 3 described in the thermochromic film 103, the vanadium dioxide-containing particles 13 are prepared using a flow reactor, which is a flow reactor shown in FIG. 3, according to the following method. did.

  Vanadium dioxide-containing particles 3 were dispersed in purified water to prepare a 0.03 mol / L vanadium dioxide-containing particle 3 water slurry. As a hydrophobic organic compound forming the third shell layer, a toluene solution of hexanoic acid (0.12 mol) was prepared as Compound B2. The flow rates of the preheated water, the vanadium dioxide-containing particles 3 slurry, and the toluene solution of compound B2 were 12 ml / min, 3 ml / min, and 3 ml / min, respectively. Next, the inside of the system was set to 30 MPa by a back pressure valve.

  Next, the cartridge heater was energized to heat the preheated water to a predetermined temperature. Simultaneously with energization, the cooling water circulation device was turned on to start cooling. After confirming that the temperature of each part was stabilized, the pump which sent purified water was switched to the toluene solution of vanadium dioxide containing particle | grain 3 slurry and compound B2, and it sent.

  After a predetermined time, the line of the recovery unit was returned to the opposite line, and heating of the electric furnace and the flexible heater was stopped. Thereafter, the liquid feed pump 2 was switched from an aqueous solution containing vanadium dioxide-containing particles 3 to purified water, and the reaction was terminated. After confirming that the temperature in the tube was 100 ° C. or lower, the back pressure valve was opened to return the pressure in the system to normal pressure. The cooling water circulation device was turned off and the cooling was stopped.

  The product was transferred from the syringe-type collection container to a beaker, and the product was washed out of the container with 20 ml of toluene. Thereafter, the water phase and the toluene phase were separated, and the vanadium dioxide-containing particles 13 that were transferred to the toluene phase were adjusted to 3% by mass to prepare vanadium dioxide-containing particles 13.

  In producing the thermochromic film 109, a thermochromic film 113 was produced in the same manner except that the prepared vanadium dioxide-containing particles 13 were used instead of the vanadium dioxide-containing particles 9.

[Preparation of Thermochromic Film 114: Hydrophobic]
After the dispersion containing the vanadium dioxide-containing particles 3 described in the thermochromic film 103 is concentrated to 1/5 using an ultrafilter (Vivaflow Co., Ltd.), acetonitrile is added and the original liquid is added. The operation of returning to the liquid volume was repeated 4 times, and the solvent was replaced with acetonitrile. Then, as a hydrophobic organic compound, Compound B3 (hexamethyldisilazane, SZ-31, manufactured by Shin-Etsu Silicone) was added and stirred. By reacting for a period of time, a third shell layer composed of a hydrophobic organic compound was formed, and a solvent dispersion containing vanadium dioxide-containing particles 14 was prepared.

  In producing the thermochromic film 113, a thermochromic film 114 was produced in the same manner except that the vanadium dioxide-containing particles 14 prepared above were used instead of the vanadium dioxide-containing particles 13.

[Preparation of Thermochromic Film 115: Hydrophobic]
In producing the thermochromic film 114, a thermochromic film 115 was produced in the same manner except that the vanadium dioxide-containing particles 15 prepared by the following method were used in place of the vanadium dioxide-containing particles 14.

(Preparation of vanadium dioxide-containing particles 15)
In preparation of the vanadium dioxide-containing particles 114, tungsten (W) was added as a transition temperature adjusting agent at the time of core particle preparation so that vanadium atoms would be 99 atm% and tungsten (W) would be 1 atm% to dope tungsten. Vanadium dioxide-containing particles 15 were prepared in the same manner except that the core particles (II) were used.

  The details of each additive used for producing the thermochromic film are as follows.

<Hydrophobic organic compound>
Compound B1: Hexyltriethoxysilane (trade name: KBE-3063, manufactured by Shin-Etsu Silicone)
Compound B2: hexanoic acid (caproic acid, CH ₃ (CH ₂ ) ₄ COOH)
Compound B3: Hexamethyldisilazane (trade name; SZ-31 manufactured by Shin-Etsu Silicone)
<Binder resin>
S1: Hydrophilic binder Kuraray Poval PVA105 (polyvinyl alcohol resin, Kuraray Co., Ltd.)
O1: Hydrophobic binder Byron 200 (Amorphous polyester resin, manufactured by Toyobo Co., Ltd.)
<Evaluation of thermochromic film>
Next, each of the thermochromic films prepared above was subjected to the following evaluations.

[Evaluation of preservability]
The spectral transmittance of each of the produced thermochromic films in an environment of 25 ° C. and 80 ° C. (50% RH) is an infrared region using a spectral transmittance meter V-770 manufactured by JASCO Corporation. Each transmittance at 1500 nm was measured, and the change rate of the spectral transmittance between temperatures was determined.

  Next, each thermochromic film was subjected to a forced deterioration treatment for 3 days in a high-temperature and high-humidity environment of 60 ° C. and 90% RH, and then the rate of change in spectral transmittance between the same temperatures as described above was obtained. The reduction rate (%) of the change rate before and after the treatment was determined, and the storage stability was evaluated according to the following evaluation criteria. Even after storage in a high-temperature and high-humidity environment of 60 ° C. and 90% RH, it was determined that the durability was excellent if the reduction rate was small.

  The rate of change (%) and the rate of decrease (%) were determined by the following method.

The rate of change (%) = [spectral transmittance lambda ₁₅₀₀ at / 25 ° C. (spectral transmittance lambda ₁₅₀₀ in the spectral transmittance lambda ₁₅₀₀ -80 ° C. at 25 ° C.)] × 100
Reduction rate (%) = [1− (change rate after forced deterioration processing) / (change rate before forced deterioration processing)] × 100
◎: Reduction rate is less than 2.0% ○: Reduction rate is 2.0% or more and less than 5.0% △: Reduction rate is 5.0% or more and less than 10.0% Yes x: Decrease rate is 10.0% or more [Evaluation of thermochromic response]
Each thermochromic film was bonded to a glass substrate only on one side of a space of 20 cm × 20 cm × 20 cm closed with a vacuum heat insulating material, and arranged so that the inside became a thermochromic film. A thermometer was installed at a position 19 cm away from the glass with the thermochromic film bonded inside the heat insulating space, and a 150 W halogen lamp was lit from the position 10 cm away from the outside where the glass with the thermochromic film bonded was placed. . The time (second / ° C.) required for the temperature to rise by 1 ° C. after the halogen lamp was turned on was measured, and the thermochromic response was evaluated according to the following criteria.

◎: Temperature rise time (second / ° C) is 300 seconds or more ○: Temperature rise time (second / ° C) is 120 seconds or more and less than 300 seconds △: Temperature rise time (second / ° C) 60 seconds or more and less than 120 seconds x: Temperature rise time (second / ° C.) is less than 60 seconds [Evaluation of repeated resistance]
Each thermochromic film was subjected to 1000 times of repeated temperature changes at 80 ° C. and −20 ° C. (storage time: 10 minutes at each temperature) using a thermal shock apparatus TSA-103EL manufactured by Espec.

  Subsequently, the change rate of the spectral transmittance before and after the temperature change treatment was measured by the same method as the evaluation of the storage stability, the decrease rate was calculated, and the repeated resistance was evaluated according to the following evaluation criteria. If the rate of decrease in the rate of change before and after 1000 iterations was small, it was determined that the repeat resistance was excellent.

◎: Reduction rate is less than 2.0% ○: Reduction rate is 2.0% or more and less than 5.0% △: Reduction rate is 5.0% or more and less than 10.0% Yes x: Decrease rate is 10.0% or more Table 1 shows the results obtained.

  As is clear from the results shown in Table 1, the thermochromic film of the present invention has high durability, excellent thermochromic responsiveness, and good repeatability compared to the comparative example. I understand.

1a, 1b Thermochromic vanadium dioxide-containing particles 2 Core particles 3 First shell layer 4 Second shell layer 5 Third shell layer 11 Thermochromic film 12 Transparent substrate 13 Optical functional layer 12 + 13 Hybrid optical functional layer 14 Near infrared light Shielding layer 50 Solvent replacement treatment device 51 Preparation kettle 52 Mixed solution containing vanadium dioxide-containing particles 53 Circulation line 54 Circulation pump 55 Ultrafiltration unit 56 Discharge port 57 Solvent stock kettle 58 Solvent 59 Solvent supply line 100 Flow type reactor 101 High pressure Raw material liquid 102 Preheated water 103 Hydrophobic organic compound solution 104 Vanadium dioxide-containing particles 105 Water supply path 106 Hydrophobic organic compound supply path 107 Raw material supply path B1, B2 Hydrophobic binder L Light incident side M Modification part C Cooling part G Recovery part P Pump H He Secondary particles of primary particles VO _M vanadium dioxide containing particles of over V back pressure valve VO _S vanadium dioxide containing particles

Claims (11)

Thermochromic vanadium dioxide-containing particles having a core-shell structure,
Having vanadium dioxide particles in the core, and
A first shell layer made of an organic compound having at least a hydroxy group that modifies the surface of the vanadium dioxide particles;
A second shell layer containing an amorphous metal oxide;
In this order, thermochromic vanadium dioxide-containing particles.   The amorphous metal oxide contained in the second shell layer is at least one selected from silicon oxide, titanium oxide, zinc oxide, hafnium oxide, cerium oxide, and molybdenum oxide. Thermochromic vanadium dioxide-containing particles.   The thermochromic vanadium dioxide-containing particles according to claim 1 or 2, wherein the organic compound contained in the first shell layer has an amino group or a nitrogen-containing heterocyclic group together with a hydroxy group.   The thermochromic vanadium dioxide according to any one of claims 1 to 3, further comprising a third shell layer containing a hydrophobic organic compound on the surface of the second shell layer. Containing particles.   The hydrophobic organic compound contained in the third shell layer is a compound having a hydrophobic alkyl group or a hydrophobic aryl group and at least one group selected from silazane, silicon alkoxide, alcohol, aldehyde, and carboxylic acid. The thermochromic vanadium dioxide-containing particles according to claim 4.   The thermochromic vanadium dioxide-containing particles according to any one of claims 1 to 5, further comprising a compound containing an element having an effect of adjusting a phase transition temperature. A method for producing thermochromic vanadium dioxide-containing particles for producing the thermochromic vanadium dioxide-containing particles according to any one of claims 1 to 6,
As a first shell layer forming step, a step of forming a shell layer by adding and dispersing an organic compound having at least a hydroxy group to an aqueous dispersion containing vanadium dioxide particles as core particles;
A thermochromic vanadium dioxide characterized in that, as the second shell layer forming step, an amorphous metal oxide forming precursor, a step of adding an alkali and alcohol to form a shell layer having an amorphous metal oxide Production method of contained particles. A method for producing thermochromic vanadium dioxide-containing particles for producing the thermochromic vanadium dioxide-containing particles according to any one of claims 4 to 6,
As a first shell layer forming step, a step of forming a shell layer by adding and dispersing an organic compound having at least a hydroxy group to an aqueous dispersion containing vanadium dioxide particles as core particles;
A step of forming an amorphous metal oxide forming precursor, an alkali and an alcohol to form a shell layer having an amorphous metal oxide as a second shell layer forming step, and a third shell layer forming step As a manufacturing method of the thermochromic vanadium dioxide containing particle | grains characterized by having any process of the following process (3-1) or (3-2) as.
Step (3-1): The aqueous medium of the aqueous dispersion containing the vanadium dioxide particles forming the second shell layer is replaced with an organic solvent not containing a hydroxy group by ultrafiltration, and then the hydrophobic having a silazane group Forming a third shell layer by surface modification with an organic compound,
Step (3-2): treatment with a hydrophobic organic compound having at least one group selected from silicon alkoxide, alcohol, aldehyde and carboxylic acid in the presence of high-temperature high-pressure water in a subcritical state, or a subcritical state A hydrophobic organic compound having at least one group selected from silicon alkoxide, alcohol, aldehyde and carboxylic acid in the presence of high-temperature high-pressure water in a supercritical state after pretreatment in the presence of high-temperature high-pressure water in Forming a third shell layer by surface modification.   A thermochromic film comprising the thermochromic vanadium dioxide-containing particles according to any one of claims 1 to 6.   The thermochromic film according to claim 9, further comprising a hydrophobic binder. A method for producing a thermochromic film containing thermochromic vanadium dioxide-containing particles,
It manufactures by mixing the vanadium dioxide containing particle manufactured by the manufacturing method of the thermochromic vanadium dioxide containing particle of Claim 7 or Claim 8, and a hydrophobic binder at least, and apply | coating and drying. A method for producing a thermochromic film.

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