JPWO2018105238A1 - Vanadium dioxide-containing particles, thermochromic film, and method for producing vanadium dioxide-containing particles - Google Patents

Abstract

An object of the present invention is to provide vanadium dioxide-containing particles that change the light transmittance due to a temperature change in the visible light region and further increase the change width of the light transmittance due to the temperature change in the infrared light region. The vanadium dioxide-containing particles of the present invention have thermochromic properties and contain an element A selected from group 2 of the periodic table and an element B selected from group 5 or 6 of the periodic table excluding vanadium. , With respect to vanadium (100 atom%), the total content of element A is in the range of 0.5 to 20 atom%, and the total content of element B is in the range of 0.05 to 20 atom%. Features.

Description

  The present invention relates to a method for producing vanadium dioxide-containing particles, thermochromic film, and vanadium dioxide-containing particles. More specifically, the light transmittance is changed by temperature change in the visible light region, and light caused by temperature change in the infrared light region. The present invention relates to a vanadium dioxide-containing particle, a thermochromic film, and a method for producing vanadium dioxide-containing particles that further increase the width of change in transmittance.

  For example, in a building such as a house or a building, or a moving body such as a vehicle, energy saving is achieved at a location (for example, a window glass) where a large heat exchange occurs between the inside (for example, indoors or inside the vehicle) and the external environment. In order to achieve both comfort and comfort, application of a material having thermochromic properties (hereinafter, also referred to as “thermochromic material”) capable of controlling the blocking or transmission of heat is expected.

  Here, the “thermochromic material” is a material in which optical properties such as a transparent state / reflective state change reversibly with temperature. For example, a material that is in a reflective state when the temperature is high and a transparent state when the temperature is low. When such a thermochromic material is applied to a window glass of a building, for example, it can reflect sunlight in the summer to block heat, and in winter it can transmit sunlight and use heat, Both energy saving and comfort can be achieved.

At present, one of the thermochromic materials that has received the most attention is vanadium dioxide (VO ₂ ) particles. It is known that vanadium dioxide particles exhibit thermochromic properties during a phase transition near room temperature. Therefore, by utilizing this property, thermochromic properties depending on the environmental temperature can be obtained.

Here, vanadium dioxide has several polymorphs of crystal phases such as A phase, B phase, C phase and R phase, but the crystal structure exhibiting the thermochromic characteristics as described above has a rutile type. It is limited to the crystal phase (hereinafter referred to as “R phase”). Since this R phase has a monoclinic structure below the transition temperature, it is also called an M phase.
In such vanadium dioxide particles, in order to exhibit substantially excellent thermochromic properties, it is desirable that the particles do not have a metal that does not exhibit thermochromic properties or a crystalline phase other than the M phase of vanadium dioxide. . In order to obtain good optical properties (low haze), the particle diameter of the vanadium dioxide particles is as uniform and small as possible (100 nm or less), the vanadium dioxide particles are not aggregated, and the particles are isotropic. It is desirable to have a different shape. As a technique for producing such particles, a synthesis method using a hydrothermal reaction has been reported.

For example, Patent Document 1 includes hydrazine (N ₂ H ₄ ) or a hydrate thereof (N ₂ H ₄ .nH ₂ O) and water using divanadium pentoxide (V ₂ O ₅ ) or the like as a raw material. In addition, vanadium dioxide (VO ₂ ) single crystal fine particles obtained by hydrothermal reaction of a solution substantially free of titanium dioxide (TiO ₂ ) particles are disclosed.
However, as shown in FIG. 9 (Example 3), the vanadium dioxide particles have a change in light transmittance when the temperature is increased, which is longer than about 600 nm (mainly infrared light). Only when it is applied as a thermochromic material, the effect cannot be fully exhibited, and it is difficult to visually perceive the thermochromic phenomenon.

Further, Patent Document 2, magnesium or aluminum is doped, its chemical composition is _{V 1-x M x O 2} : vanadium dioxide powder is disclosed which is (M Mg or Al).
However, as in Patent Document 1, as shown in FIG. 8 (Example 10), the vanadium dioxide powder has a light transmittance change longer than about 600 nm (mainly in the infrared region). ) Only when it is applied as a thermochromic material, the effect cannot be fully exhibited, and it is difficult to visually perceive the thermochromic phenomenon.

JP2011-178825A Chinese Patent Application Publication No. 104030356

  The present invention has been made in view of the above-described problems and situations, and its solution is to change the light transmittance due to temperature changes in the visible light region, and to change the light transmittance due to temperature changes in the infrared light region. It is to provide a vanadium dioxide-containing particle that further increases the width, a thermochromic film containing the particle, and a method for producing the vanadium dioxide-containing particle.

  In order to solve the above problems, the present inventor selected from the element A selected from the group 2 of the periodic table of elements and the group 5 or 6 of the periodic table excluding vanadium in the process of examining the cause of the above problems. Element B and the total content of element A and element B within a specific range with respect to vanadium (100 atom%), the light transmittance is changed by the temperature change in the visible light region, and red The present inventors have found that a vanadium dioxide-containing particle that can further increase the width of change in light transmittance due to a temperature change in an outside light region, a thermochromic film containing the same, and a method for producing the vanadium dioxide-containing particle can be provided.

  That is, the said subject which concerns on this invention is solved by the following means.

1. Vanadium dioxide-containing particles having thermochromic properties,
An element A selected from group 2 of the periodic table and an element B selected from group 5 or 6 of the periodic table excluding vanadium,
The total content of the element A is in the range of 0.5 to 20 atom% and the total content of the element B is in the range of 0.05 to 20 atom% with respect to vanadium (100 atom%). Vanadium-containing particles.

2. The element B is tungsten;
The vanadium dioxide-containing particles according to item 1, wherein the tungsten content is in the range of 0.5 to 10 atom% with respect to vanadium (100 atom%).

3. The element B is molybdenum;
The vanadium dioxide-containing particles according to item 1 or 2, wherein the molybdenum content is in the range of 0.5 to 10 atom% with respect to vanadium (100 atom%).

4). The element A is magnesium;
The vanadium dioxide-containing particles according to any one of items 1 to 3, wherein the magnesium content is within a range of 0.5 to 10 atom% with respect to vanadium (100 atom%).

  5). A thermochromic film containing the vanadium dioxide-containing particles according to any one of items 1 to 4.

6. The thermochromic film according to item 5, wherein a color difference ΔE ^* ab accompanying a temperature change from 15 ° C. to 70 ° C. satisfies the following formula (1).

4.0 ≦ ΔE ^* ab ≦ 6.5 (1)

7). A method for producing vanadium dioxide-containing particles having thermochromic properties,
Preparing a reaction solution comprising a vanadium-containing compound, an element A selected from group 2 of the periodic table, an element B selected from group 5 or 6 of the periodic table excluding vanadium, and water;
Hydrothermal reaction of the reaction solution to form vanadium dioxide-containing particles;
Have
In the step of preparing the reaction solution, the total addition amount of the element A is within a range of 0.5 to 20 atom% with respect to vanadium (100 atom%), and the total addition amount of the element B is 0.05 to A method for producing vanadium dioxide-containing particles in a range of 20 atom%.

  8). The manufacturing method of the vanadium dioxide containing particle | grains of Claim 7 whose said vanadium containing compound is a vanadium (IV) containing compound.

  9. In the step of forming vanadium dioxide-containing particles, the vanadium dioxide-containing material according to item 7 or 8, wherein the hydrothermal reaction is performed within a liquid temperature range of 250 to 450 ° C and a reaction time of 1 second to 48 hours. Particle production method.

  By the above means of the present invention, the vanadium dioxide-containing particles that change the light transmittance due to temperature change in the visible light region and further increase the change width of the light transmittance due to temperature change in the infrared light region, and a thermo containing the same A method for producing a chromic film and vanadium dioxide-containing particles can be provided.

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

The vanadium dioxide-containing particles of the present invention contain an element A selected from group 2 of the periodic table and an element B selected from group 5 or 6 of the periodic table excluding vanadium, and vanadium (100 atom%). On the other hand, the total content of the element A is in the range of 0.5 to 20 atom%, and the total content of the element B is in the range of 0.05 to 20 atom%. In the light region, the light transmittance is changed due to a temperature change, and in the infrared light region, the change width of the light transmittance due to the temperature change is further increased as compared with the conventional case.
Although this mechanism has not been elucidated, doping the group 5 element 6 and the group 5 element 6 other than the group 2 element A and vanadium changes the structure in the phase transition of the vanadium dioxide, thereby changing the phase transition temperature. The light transmittance in the visible light / near infrared light region at a lower temperature side is increased, while the light transmittance in the visible light / infrared light region at a higher temperature side than the phase transition temperature is further decreased, that is, It is speculated that the optical change has been expanded by causing an increase in the light transmittance change width in the infrared light region and a change in the light transmittance in the visible light region.

Schematic which shows an example of the flow-type reaction apparatus which comprises the hydrothermal reaction part applicable to manufacture of the vanadium dioxide containing particle | grains of this invention.

  The vanadium dioxide-containing particles of the present invention contain an element A selected from group 2 of the periodic table and an element B selected from group 5 or 6 of the periodic table excluding vanadium, and vanadium (100 atom%). On the other hand, the total content of element A is in the range of 0.5 to 20 atom%, and the total content of element B is in the range of 0.05 to 20 atom%. This feature is a technical feature common to the inventions according to the following embodiments.

  As an embodiment of the present invention, it is preferable that the element B is tungsten or molybdenum, and the content of the tungsten or molybdenum is in the range of 0.5 to 10 atom% with respect to vanadium (100 atom%). If the content of the element B is within the above range, the optical change in the visible light part due to heat becomes large, and the element B is less likely to cause a decrease in crystal regularity as an impurity and maintain thermochromic properties (optical change). Can do.

  Moreover, it is preferable that the element A is magnesium and content of the said magnesium exists in the range of 0.5-10 atom% with respect to vanadium (100 atom%). If the content of the element A is within the above range, the optical change of the visible light part due to heat becomes large, and the element A is not likely to cause a decrease in crystal regularity as an impurity and maintain thermochromic properties (optical change). Can do.

  The present invention can provide a thermochromic film containing the vanadium dioxide-containing particles.

Moreover, it is preferable that the color difference (DELTA) E ^* ab accompanying the temperature change from 15 degreeC to 70 degreeC satisfy | fills the thermochromic film of this invention satisfy | fills Formula (1).

  The present invention is a method for producing thermochromic vanadium dioxide-containing particles, comprising a vanadium-containing compound, an element A selected from group 2 of the element periodic table, and group 5 or group 6 of the element periodic table excluding vanadium. In the step of preparing the reaction solution, the step of preparing a reaction solution containing the element B selected from the above and the step of preparing a reaction solution comprising hydrothermal reaction of the reaction solution to form vanadium dioxide-containing particles, Vanadium dioxide-containing particles having a total addition amount of element A in the range of 0.5 to 20 atom% and a total addition amount of element B in the range of 0.05 to 20 atom% with respect to vanadium (100 atom%) The manufacturing method of can be provided.

  Further, from the viewpoint of suppressing a decrease in crystal regularity, the vanadium-containing compound is preferably a vanadium (IV) -containing compound.

  In addition, from the viewpoint of improving crystal regularity and narrowing the transition temperature range, in the step of forming vanadium dioxide-containing particles, the liquid temperature is in the range of 250 to 450 ° C., and the reaction time is in the range of 1 second to 48 hours. It is preferable to make it hydrothermally react.

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

<< Vanadium dioxide containing particles (VO ₂ containing particles) >>
The vanadium dioxide-containing particles having thermochromic properties of the present invention contain an element A selected from Group 2 of the periodic table and an element B selected from Group 5 or 6 of the periodic table excluding vanadium, and vanadium. (100 atom%), the total content of element A is in the range of 0.5 to 20 atom%, and the total content of element B is in the range of 0.05 to 20 atom%, To do.

The element A is not particularly limited as long as it is an element selected from Group 2 of the periodic table, and may be used alone or in combination of two or more. When using 2 or more types mixedly, the total content of the group 2 element of the periodic table of elements should just be in the range of 0.5-20 atom%. The total content of group 2 elements in the periodic table is preferably in the range of 0.5 to 15 atom%, more preferably in the range of 1.0 to 12 atom%, particularly preferably 5.0 to 10 atom%. %.
Among them, the element A is preferably magnesium (Mg), and the content at this time is preferably in the range of 0.5 to 10 atom% with respect to vanadium (100 atom%). If the magnesium content is 0.5 atom% or more, it is sufficient as the amount of magnesium taken into the particles, the optical change in the visible light region due to temperature changes increases, and if the content is 10 atom% or less, it is added. The resulting metal is less likely to cause a decrease in crystal regularity as an impurity, and a decrease in thermochromic properties (optical change) can be suppressed.

The element B is not particularly limited as long as it is an element selected from Group 5 or Group 6 of the periodic table other than vanadium, and may be used alone or in combination of two or more. Good. When using 2 or more types in mixture, the total content of the group 5 or group 6 element of the periodic table excluding vanadium may be in the range of 0.05 to 20 atom%. The total content of elements selected from Group 5 or Group 6 of the periodic table excluding vanadium is preferably in the range of 0.5 to 10 atom%, more preferably in the range of 0.7 to 5.0 atom%. And particularly preferably within the range of 1.0 to 3.0 atom%.
Among them, the element B is preferably tungsten (W) or molybdenum (Mo), and more preferably tungsten and molybdenum are used in combination. In any case, the preferable content of each is in the range of 0.5 to 10 atom% for tungsten and in the range of 0.5 to 10 atom% for molybdenum with respect to vanadium (100 atom%). If the content of tungsten or molybdenum is 0.5 atom% or more, it is sufficient as the amount of tungsten or molybdenum taken into the particles, the optical change in the visible light region due to temperature change becomes large, and the content is 10 atom% or less. If so, the added metal is unlikely to cause a decrease in crystal regularity as an impurity, and a decrease in thermochromic properties (optical change) can be suppressed.

<Thermochromic properties (TC properties)>
As the thermochromic property of the vanadium dioxide-containing particles of the present invention, the added value of the light transmittance difference is preferably 80% or more, more preferably 90% or more, and particularly preferably 100% or more. .
The added value of the light transmittance difference was determined by measuring the light transmittance at a wavelength of 1000 nm, 1100 nm, and 1200 nm under the conditions of 15 ° C. and 70 ° C. for the film containing vanadium dioxide-containing particles. It can be calculated by calculating the difference in light transmittance at ° C. and adding them. The light transmittance is measured by attaching a temperature control unit (manufactured by JASCO Corporation) to a spectrophotometer V-670 (manufactured by JASCO Corporation).

<Average particle size of vanadium dioxide-containing particles>
The average particle size of the vanadium dioxide-containing particles is preferably in the range of 5 to 50 nm. The average particle size of the vanadium dioxide-containing particles is measured with respect to 100 vanadium dioxide-containing particles by taking the particles with a scanning electron microscope, defining the diameter of a circle having an area equal to the projected area of the particles as the particle size, The arithmetic average value of these is calculated | required and let this be an average particle diameter.

The median diameter (D50) of the particle size distribution of the vanadium dioxide-containing particles is preferably 150 nm or less.
The median diameter (D50) of the particle size distribution of the vanadium dioxide-containing particles is determined by using each of the prepared dispersions after hydrothermal reaction (details will be described later) using a laser diffraction particle size distribution analyzer manufactured by Shimadzu Corporation. After diluting the diffracted / scattered light intensity to be between 35 and 75% (absolute value 700 to 1500), the particle diameter D50 of the vanadium dioxide-containing particles can be measured as an index of particle diameter. The measured value uses a volume conversion value. The smaller the value of D50, the smaller the particle size.

<< Method for producing vanadium dioxide-containing particles >>
The method for producing vanadium dioxide-containing particles of the present invention comprises a vanadium-containing compound, an element A selected from group 2 of the periodic table, an element B selected from group 5 or 6 of the periodic table excluding vanadium, and water. And a step of hydrothermally reacting the reaction solution to form vanadium dioxide-containing particles, and in the step of preparing the reaction solution, for vanadium (100 atom%), The total addition amount of the element A is in the range of 0.5 to 20 atom%, and the total addition amount of the element B is in the range of 0.05 to 20 atom%.
Below, the manufacturing method of the vanadium dioxide containing particle | grains which has the thermochromic property of this invention is demonstrated in detail.

(1) Step of preparing reaction solution First, in the method for producing vanadium dioxide-containing particles of the present invention, the vanadium-containing compound, the element A selected from group 2 of the periodic table, and the group 5 of the periodic table excluding vanadium or A reaction solution containing an element B selected from Group 6 and water is prepared.

(Vanadium compounds)
Examples of the vanadium-containing compound according to the present invention include compounds containing pentavalent or tetravalent vanadium.
When a compound containing pentavalent vanadium is used as the vanadium-containing compound, a reducing agent such as hydrazine (N ₂ H ₄ ) or a hydrate thereof (N ₂ H ₄ .nH ₂ O) as described later is required. It becomes. Since these reducing agents have a strong reducing effect and are liable to cause overreduction, they cause a decrease in crystal regularity. Therefore, the vanadium-containing compound is preferably a tetravalent vanadium-containing compound.

Examples of pentavalent vanadium-containing compounds (vanadium (V) -containing compounds) include divanadium pentoxide (V ₂ O ₅ ), ammonium vanadate (NH ₄ VO ₃ ), vanadium trichloride oxide (VOCl ₃ ), and sodium vanadate. (NaVO ₃ ) and the like.
Examples of tetravalent vanadium-containing compounds (vanadium (IV) -containing compounds) include vanadyl oxalate (VOC ₂ O ₄ ), vanadium oxide sulfate (VOSO ₄ , hereinafter also referred to as vanadyl sulfate), and divanadium tetroxide (V ₂ ). the O ₄₎ include those obtained by dissolving an acid such as sulfuric acid.
The vanadium-containing compound may be dissolved or dispersed in the raw material liquid. Moreover, a vanadium containing compound may be used individually by 1 type, and 2 or more types may be mixed and used for it. These compounds may be hydrated (hydrate).

(Additive elements)
In the step of preparing the reaction solution, in addition to the vanadium-containing compound, an element A selected from group 2 of the periodic table of elements and an element B selected from group 5 or 6 of the periodic table of elements other than vanadium are added. It is characterized by.
The total addition amount of the element A is in the range of 0.5 to 20 atom% with respect to vanadium (100 atom%).
The total amount of element B added is in the range of 0.05 to 20 atom% with respect to vanadium (100 atom%).

  As an aspect of the element A and the element B added to the reaction solution, a single element may be used, or a compound containing the element A or the element B may be used as long as the effects of the present invention are not impaired.

(water)
Although the water which concerns on this invention is not specifically limited, The highly purified thing with few impurities is preferable, Specifically, purified water, such as ion-exchange water and distilled water, can be used.

(Reducing agent)
When a pentavalent vanadium-containing compound is employed as the vanadium-containing compound according to the present invention, a reducing agent is used.
The reducing agent has a property of being easily dissolved in water, and may function as a reducing agent for pentavalent vanadium-containing compounds. For example, hydrazine such as hydrazine (N ₂ H ₄ ) and hydrazine monohydrate (N ₂ H ₄ · nH ₂ O) and the like.

(Other)
The reaction solution according to the present invention may be a mixture of substances having oxidizing properties or reducing properties. An example of such a substance is hydrogen peroxide (H ₂ O ₂ ). By adding an oxidizing or reducing substance, the pH of the reaction solution can be adjusted, or the vanadium-containing compound can be uniformly dissolved.
In addition, as hydrogen peroxide, hydrogen peroxide water (concentration 35 mass%, the Wako Pure Chemical Industries make, special grade) can be used suitably, for example.

(2) Hydrothermal reaction process Next, the prepared reaction liquid is hydrothermally reacted to form vanadium dioxide-containing particles.
Here, “reacting the reaction solution hydrothermally” means performing a hydrothermal reaction treatment on the reaction solution. “Hydrothermal reaction” means supercritical in hot water (subcritical water) whose temperature and pressure are lower than the critical point of water (374 ° C., 22 MPa), or higher in temperature and pressure than the critical point of water. A chemical reaction that occurs in water. Subcritical water refers to water in a state where the temperature is in the range of 150 to 374 ° C. and the pressure is higher than the saturated water vapor pressure at that temperature.
A hydrothermal reaction process is implemented in an autoclave apparatus, for example. By the hydrothermal reaction treatment, particles containing vanadium dioxide are obtained. In addition, a continuous method can be used in which a high pressure and high pressure water in a subcritical or supercritical state is mixed and synthesized using a flow type reactor (flow reactor) such as a pressure resistant tube type or tank type, and in particular, a tube. A continuous process using a reactor of the type can be suitably used.

  Hydrothermal reaction treatment conditions (amount of reactants, treatment temperature, treatment pressure, treatment time) are set as appropriate, but as hydrothermal reaction treatment conditions, the liquid temperature is in the range of 250 to 450 ° C, and The reaction time is preferably in the range of 1 second to 48 hours. If the reaction treatment temperature and time are equal to or higher than the lower limit value, crystallization is promoted, the optical property change is large and the transition temperature range is narrowed. And the change in optical characteristics can be maintained.

In the present invention, the transition temperature width of the vanadium dioxide-containing particles is measured as follows.
First, an aqueous dispersion containing vanadium dioxide-containing particles is prepared and mixed in polyvinyl alcohol dissolved in water. This mixed solution is applied onto a PET film, applied with a wire bar so that the film thickness after drying becomes a predetermined thickness, and then dried to produce a measurement film.
Using this measurement film, the temperature is changed in increments of 1 ° C. from 10 ° C. to 85 ° C., the light transmittance at a wavelength of 2000 nm at each temperature is measured, and the transition temperature width is calculated. Specifically, the lowest temperature at which the light transmittance difference becomes 1% or more with respect to the light transmittance measured at 10 ° C. is the transition start temperature, and the light transmittance difference with respect to the light transmittance measured at 85 ° C. When there is no temperature at which the temperature is less than 1% or the light transmittance difference is less than 1%, 85 ° C. is used as the transition end temperature, and the transition temperature width is calculated by the following formula.

  Transition temperature width (° C.) = Transition end temperature−Transition start temperature

  The transition temperature width of the vanadium dioxide-containing particles of the present invention is preferably in the range of 1 to 25 ° C.

The solid content concentration of vanadium dioxide derived from the vanadium-containing compound in the hydrothermal reaction is preferably in the range of 0.1 to 20% by mass.
When the solid content concentration of vanadium dioxide is in the range of 0.1 to 20% by mass, crystal growth can be suppressed and dispersion stabilization can be achieved.

In addition, it is preferable that the hydrothermal reaction is performed with stirring because the particle diameter of the vanadium dioxide-containing particles can be made more uniform.
In addition, the hydrothermal reaction process may be implemented by a batch type and may be implemented by a continuous type.

《Thermochromic film》
The thermochromic film of the present invention contains the vanadium dioxide-containing particles of the present invention described above.

In the thermochromic film of the present invention, it is preferable that the color difference ΔE ^* ab accompanying the temperature change from 15 ° C. to 70 ° C. satisfies the following formula (1) based on JIS Z 8781-4: 2013.

4.0 ≦ ΔE ^* ab ≦ 6.5 (1)

  Hereinafter, although the film provided with the transparent base material and the optical function layer is demonstrated as an example as a thermochromic film of this invention, it is not limited to this in particular.

  A thermochromic film is provided with a transparent base material and an optical functional layer, and the optical functional layer preferably contains a resin and the vanadium dioxide-containing particles of the present invention described above.

  The transparent base material applicable to the thermochromic film is not particularly limited as long as it is transparent, and examples thereof include glass, quartz, and a transparent resin film. However, flexibility and production suitability (roll to roll suitability) can be exemplified. From this point of view, a transparent resin film is preferable. The term “transparent” in the transparent substrate 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%. That's it.

  The thickness of the transparent substrate 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 and the like are less likely to occur during handling, and if the thickness is 200 μm or less, the curved surface of the glass when bonded to the glass substrate when making laminated glass The follow-up to is improved.

  The transparent base material preferably 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. It is more preferably in the range of 0%, and still more preferably in the range of 1.9 to 2.7%.

  As described above, the transparent substrate applicable to the thermochromic film is not particularly limited as long as it is transparent, and various transparent resin films can be used. For example, polyolefin films (for example, polyethylene films, polypropylene films) Etc.), polyester film (for example, polyethylene terephthalate film, polyethylene naphthalate film, etc.), polyvinyl chloride film, triacetyl cellulose film, etc., preferably polyester film, triacetyl cellulose film, more preferably It is a polyester film.

  The transparent resin film is particularly preferably a biaxially oriented polyester film, but a uniaxially stretched polyester film that is unstretched or stretched at least in one direction can also be used. A stretched film is preferable from the viewpoint of strength improvement and thermal expansion suppression. In particular, when a laminated glass provided with a thermochromic film is used as an automobile windshield, a stretched film is more preferable.

When a transparent resin film is used as the transparent substrate, fine particles may be contained within a range that does not impair the transparency in order to facilitate handling. Examples of the fine particles applicable to the transparent resin film include inorganic fine particles such as calcium carbonate, calcium phosphate, silica, kaolin, talc, titanium dioxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide. And organic fine particles such as crosslinked polymer fine particles and calcium oxalate.
Examples of the method of adding the fine particles include a method of adding fine particles into a resin (for example, polyester) as a raw material for forming the transparent resin film, a method of directly adding to the extruder, and the like. Either of these methods may be employed, or two methods may be used in combination. In addition to the fine particles, various additives may be added to the transparent resin film as necessary. Examples of such additives include stabilizers, lubricants, crosslinking agents, anti-blocking agents, antioxidants, dyes, pigments, ultraviolet absorbers, and the like.

  On the transparent substrate, an optical functional layer containing the resin and the vanadium dioxide-containing particles of the present invention is provided.

Here, the resin is not particularly limited, and a resin similar to that generally used for an optical functional layer of a thermochromic film (optical film) can be used, and preferably a water-soluble polymer can be used. The “water-soluble polymer” as used herein refers to a polymer that dissolves 0.001 g or more in 100 g of water at 25 ° C.
Specific examples of the water-soluble polymer include polyvinyl alcohol, polyethyleneimine, gelatin (for example, hydrophilic polymer typified by gelatin described in JP-A-2006-343391), starch, guar gum, alginate, methylcellulose, and ethylcellulose. , Hydroxyalkyl cellulose, carboxyalkyl cellulose, poly (meth) acrylamide, polyethyleneimine, polyethylene glycol, polyalkylene oxide, polyvinylpyrrolidone (PVP), polyvinyl methyl ether, carboxyvinyl polymer, poly (meth) acrylic acid, poly (meth) Sodium acrylate, naphthalenesulfonic acid condensate, proteins such as albumin and casein, sodium alginate, dextrin, dextran, dextran sulfate, etc. Mention may be made of the derivatives and the like.

  The content of vanadium dioxide-containing particles in the optical functional layer is preferably in the range of 1 to 60% by mass with respect to the total mass (100% by mass) of the optical functional layer, from the viewpoint of obtaining desired thermochromic properties. More preferably, it is in the range of 5 to 50% by mass.

  Various conventionally known additives can be used in the optical functional layer as long as the intended effects are not impaired. Various applicable additives 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, and JP-A-57-87989. Of anti-fading agents, anions, cations or nonions described in JP-A No. 60-72785, JP-A No. 61-146591, JP-A No. 1-95091 and JP-A No. 3-13376. Various surfactants, such as JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, and JP-A-4-219266. Fluorescent brighteners, sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and other pH adjusters, antifoaming agents, diethylene glycol Lubricants, antiseptics, antifungal agents, antistatic agents, matting agents, heat stabilizers, antioxidants, flame retardants, crystal nucleating agents, inorganic particles, organic particles, thinning agents, lubricants, infrared absorbers, dyes And various known additives such as pigments.

  The method for producing the thermochromic film (the method for forming the optical functional layer) is not particularly limited, and can be applied in the same manner as in a known method or by appropriately changing it except that the vanadium dioxide-containing particles of the present invention are used. Specifically, a method in which a coating solution containing vanadium dioxide-containing particles is prepared, and the coating solution is coated on a transparent substrate by a wet coating method and dried to form an optical functional layer is preferable.

  In the above method, the wet coating method is not particularly limited, and for example, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a slide type curtain coating method, or US Pat. No. 2,761,419, US Examples thereof include a slide hopper coating method and an extrusion coating method described in Japanese Patent No. 2761791.

<Dispersion>
When the vanadium dioxide-containing particles of the present invention are dispersed in water, a dispersion containing vanadium dioxide-containing particles that exhibits excellent thermochromic properties can be provided. When a dispersion containing the vanadium dioxide-containing particles is applied, a thermochromic film or the like exhibiting excellent thermochromic properties can be provided.
The solvent to be dispersed only needs to contain water, and a known solvent such as an organic solvent can be used as long as the function of vanadium dioxide is not impaired.
The thermochromic property of the aqueous dispersion containing VO ₂ -containing particles is, for example, a spectrophotometer V-670 (manufactured by JASCO Corp.), and the light transmittance at a wavelength of 2000 nm that is not affected by the absorption peak of water. It can be measured as a difference.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, the addition amount (atom%) of the element A and the element B in an Example is a value with respect to vanadium (100 atom%) in a reaction liquid. In the examples, “%” is used, but “mass%” is indicated unless otherwise specified.

<Preparation of dispersion>
Dispersions 101 to 135 containing vanadium dioxide-containing particles were prepared as follows.

<Preparation of Dispersion 101>
50 mL of a 10% by mass aqueous solution of hydrogen peroxide (concentration 35% by mass, manufactured by Wako Pure Chemical Industries), 1.5 g of vanadium pentoxide (V ₂ O ₅ , Wako Pure Chemicals, special grade) and tungsten as element B 1.00 atom% ((NH ₄ ) ₁₀ W ₁₂ O ₄ , Wako Pure Chemical Industries, 85.0 +% as WO ₃ ) was added and stirred for 4 hours to obtain a clear reddish brown sol. .
A 5% by mass aqueous solution of a reducing agent, hydrazine monohydrate (N ₂ H ₄ .H ₂ O, manufactured by Wako Pure Chemical Industries, Ltd., special grade) is slowly added dropwise to the obtained sol, and the reaction has a pH of 4.5. After preparing a liquid (liquid temperature 25 ° C.), pure water was added to prepare a solid content of 2.5% by mass in terms of vanadium dioxide.
The prepared reaction solution is put into a commercially available autoclave for hydrothermal reaction treatment (manufactured by Sanai Kagaku Co., Ltd., HU-50 type (SUS main body is provided with a 50 mL capacity Teflon (registered trademark) inner cylinder)). A dispersion liquid 101 containing vanadium dioxide-containing particles was prepared by hydrothermal reaction at 5.5 ° C. for 24 hours at a temperature of 5 ° C.

<Preparation of dispersions 102-109>
Dispersions 102 to 109 were prepared in the same manner as in the preparation of Dispersion 101, except that the types and addition amounts of Element A and Element B were changed as described in Table I. The compounds containing element A or element B used for the preparation of each dispersion are as follows.
In addition, in dispersions 103 and 104, sodium (Group 1) and yttrium (Group 3) were added in addition to molybdenum as an additive element, respectively, and in dispersion liquid 105, yttrium (Group 3) was added in addition to beryllium as an additive element. .

Magnesium: MgSO ₄ , Wako Pure Chemical Industries, 98.0 +%
Beryllium: BeSO ₄ · nH ₂ O, manufactured by Wako Pure Chemicals, 50.0 +% (as anhydride)
Tungsten: (NH ₄ ) ₁₀ W ₁₂ O ₄ , Wako Pure Chemical Industries, 85.0 +% as WO ₃
Molybdenum: (NH ₄ ) ₆ Mo ₇ O ₂₄ , Wako Pure Chemical Industries, 99.997%
Niobium: NbCl ₅ , Alfa Aesar, 99.9%
Sodium: Na ₂ SO ₄ , Wako Pure Chemical Industries, 99.0 +%
Yttrium: Y ₂ (SO ₄ ) ₃ , Alfa Aesar, 99.9%

<Preparation of dispersion 110>
Dissolve 19.0 g of vanadium oxide sulfate (VOSO ₄ ) in ion-exchanged water to 300 mL, and stir the liquid while stirring this solution as magnesium A 5.00 atom% (MgSO ₄ , Wako Pure Chemicals, 98.0 +%) In addition, as element B, tungsten is 1.00 atom% ((NH ₄ ) ₁₀ W ₁₂ O ₄ , Wako Pure Chemical Industries, 85.0 +% as WO ₃ ) and molybdenum 5.00 atom% ((NH ₄ ) ₆ Mo ₇ O _24. , Manufactured by Wako Pure Chemical Industries, Ltd., 99.997%), 68 g of 3.0 mol / L NH ₃ aqueous solution as an alkali was added to adjust the pH to 8.0 (liquid temperature 25 ° C.) to prepare a reaction solution.
This reaction liquid was put into an autoclave having an internal volume of 500 mL and subjected to hydrothermal reaction at 270 ° C. and 5.51 MPa for 24 hours to prepare dispersion 110 containing vanadium dioxide-containing particles.

<Preparation of dispersion 111>
Dispersion 111 was prepared in the same manner as in the preparation of dispersion 101, except that the types and addition amounts of element A and element B were changed as shown in Table I.

<Preparation of dispersions 112-124>
Dispersions 112 to 124 were prepared in the same manner as in the preparation of dispersion 110, except that the types and addition amounts of element A and element B were changed as described in Tables I and II.
The compound containing niobium used for the preparation of the dispersion 124 is as follows.

Niobium: NbCl ₅ , Alfa Aesar, 99.9%

<Preparation of dispersion 125>
Using the flow reactor 101 having the hydrothermal reaction section 116 shown in FIG. 1, a dispersion 125 containing vanadium dioxide-containing particles was prepared according to the following method.

First, 19.0 g of vanadium oxide sulfate (IV) (VOSO ₄ ) was dissolved in ion exchange water (dissolved oxygen amount: 8.1 mg / L) to 300 mL in the raw material liquid container 105, and this liquid was stirred, Magnesium 5.00 atom% (MgSO ₄ , Wako Pure Chemicals, 98.0 +%) as element A, tungsten 1.00 atom% ((NH ₄ ) ₁₀ W ₁₂ O ₄ , Wako Pure Chemicals, 85. 0 +% as WO ₃ ) and molybdenum 5.00 atom% ((NH ₄ ) ₆ Mo ₇ O ₂₄ , Wako Pure Chemical Industries, Ltd., 99.997%), 68 mL of 3.0 mol / L NH ₃ aqueous solution as an alkali was added. Thus, a raw material liquid 1 having a pH of 8.0 (liquid temperature: 25 ° C.) was prepared.
On the other hand, ion exchange water was stored as the raw material liquid 2 in the raw material liquid container 102.

The raw material liquid 1 containing vanadium oxide oxide (IV), element A, element B, and alkali is fed from the raw material liquid container 105 through the flow path 106 by the pump 107, and is heated by a heating medium 115 at 25 ° C. and 30 MPa. The pressure was applied so that
On the other hand, the ion-exchanged water that is the raw material liquid 2 is fed from the raw material liquid container 102 through the flow path 103 by the pump 104, and heated and pressurized by the heating medium 113 at 440 ° C. under the condition of 30 MPa to obtain supercritical water Got.

Next, the raw material liquid 1 containing vanadium oxide oxide (IV), element A, element B and alkali and the raw material liquid 2 which is supercritical water at the confluence MP are as follows: Raw material liquid 1: Raw material liquid 2 = 1 The reaction solution 1 was prepared by mixing under the conditions of 4: 4 and fed to the hydrothermal reaction section 116. In the hydrothermal reaction section 116, the reaction liquid 1 was sent to the heating section piping 117 disposed in the heating medium 114. As hydrothermal reaction conditions in the heating pipe part 117, the treatment time (passage time) was 1 minute under the conditions of 450 ° C. and 30 MPa, and vanadium dioxide (VO ₂ ) -containing particles were formed. Subsequently, the reaction liquid 1 was cooled in the cooling unit 108 to prepare a dispersion liquid 125 containing vanadium dioxide-containing particles.

<Preparation of dispersion 126>
In the preparation of dispersion 110, dispersion 126 containing vanadium dioxide-containing particles was prepared in the same manner except that the treatment temperature and pressure in the hydrothermal reaction were changed to 250 ° C. and 3.98 MPa.

<Preparation of Dispersion 127>
A dispersion 127 containing vanadium dioxide-containing particles was prepared in the same manner as in the preparation of the dispersion 125 except that the treatment temperature and pressure in the hydrothermal reaction were changed to 480 ° C. and 30 MPa.

<Preparation of dispersion 128>
In the preparation of dispersion 110, dispersion 128 containing vanadium dioxide-containing particles was prepared in the same manner except that the treatment temperature and pressure in the hydrothermal reaction were changed to 230 ° C. and 2.80 MPa.

<Preparation of dispersion 129>
A dispersion 129 containing vanadium dioxide-containing particles was prepared in the same manner except that the treatment time in the hydrothermal reaction was changed to 48 hours in the preparation of the dispersion 110.

<Preparation of dispersion 130>
In the preparation of the dispersion 125, the dispersion 130 containing vanadium dioxide-containing particles was similarly obtained except that the treatment temperature and pressure in the hydrothermal reaction were changed to 270 ° C., 5.51 MPa, and the treatment time (passage time) was changed to 1 second. Was prepared.

<Preparation of dispersion 131>
In the preparation of dispersion 110, dispersion 131 containing vanadium dioxide-containing particles was prepared in the same manner except that the treatment time in the hydrothermal reaction was changed to 120 hours.

<Preparation of dispersion liquid 132>
In the preparation of the dispersion 125, a dispersion containing vanadium dioxide-containing particles was similarly performed except that the treatment temperature and pressure in the hydrothermal reaction were changed to 270 ° C., 5.51 MPa, and the treatment time (passage time) was changed to 0.3 seconds. Liquid 132 was prepared.

<Preparation of dispersions 133-135>
In the preparation of the dispersion 125, the treatment temperature and pressure in the hydrothermal reaction were changed to 350 ° C., 16.55 MPa, and the amount of magnesium added as the element A was changed as described in Table II. 133-135 were prepared.

<Evaluation>
The following evaluation was performed about the prepared dispersion liquids 101-135.
The evaluation results are shown in Tables I and II.

<Thermochromic properties (TC properties)>
Each of the prepared dispersions was prepared to 20 g of an aqueous dispersion containing 5% by mass of vanadium dioxide-containing particles, and mixed in 10 g of polyvinyl alcohol dissolved in 90 g of water. This mixed solution was applied onto a PET film, applied with a wire bar so that the thickness after drying was 20 μm, and then dried at 60 ° C. for 24 hours to prepare a measurement film. The density | concentration of the vanadium dioxide containing particle | grains in the film for a measurement was 1 mass%, and thickness was 20 micrometers.
Using each measurement film thus prepared, the light transmittance at wavelengths of 1000 nm, 1100 nm and 1200 nm under conditions of 15 ° C. and 70 ° C. was measured, and the difference in light transmittance at 15 ° C. and 70 ° C. at each wavelength was determined. The values calculated and added were evaluated according to the following evaluation criteria. In addition, the thing whose added value of the light transmittance difference is 80% or more was set as the pass.
The light transmittance was measured by attaching a temperature control unit (manufactured by JASCO Corporation) to a spectrophotometer V-670 (manufactured by JASCO Corporation).

◎: 100% or more ○: 90% or more, less than 100% △: 80% or more, less than 90% ×: less than 80%

<Color difference>
Based on the measurement data in the evaluation of the thermochromic property, the color difference ΔE ^* ab accompanying the temperature change from 15 ° C. to 70 ° C. is calculated according to JIS Z 8781-4: 2013, and according to the following evaluation criteria. evaluated. In addition, the thing whose color difference (DELTA ⁾ E ^* ab is 4 or more was set as the pass.

◎: 6 or more ○: 5 or more, less than 6 △: 4 or more, less than 5 ×: less than 4

<Summary>
As is clear from Tables I and II, it was confirmed that the dispersion containing the vanadium dioxide-containing particles of the present invention was superior in thermochromic properties and color difference as compared with the dispersion of the comparative example.
From the above, element A selected from group 2 of the periodic table of elements and element B selected from group 5 or 6 of the periodic table of elements excluding vanadium are contained, and the total amount of element A with respect to vanadium (100 atom%) If the content is within the range of 0.5 to 20 atom% and the total content of element B is within the range of 0.05 to 20 atom%, the light transmittance changes due to temperature change in the visible light region. It can be seen that the present invention is useful for providing vanadium dioxide-containing particles that further increase the width of change in light transmittance due to temperature change in the infrared region.

  The present invention relates to a vanadium dioxide-containing particle, a thermochromic film, and a vanadium dioxide-containing particle that change the light transmittance due to a temperature change in the visible light region and further increase the change width of the light transmittance due to the temperature change in the infrared light region. It can utilize especially suitably for providing this manufacturing method.

101 Flow type reaction apparatus 102, 105 Raw material liquid container 103, 106, 111, 118 Flow path (pipe)
104, 107, 112 Pump 108 Cooling section 109, 110 Tank 113, 114, 115 Heating medium 116 Hydrothermal reaction section 117 Heating section piping 119 Control valve C Refrigerant IN Heating medium inlet OUT Heating medium outlet L Heating section piping line Long MP Junction point TC Temperature sensor

Claims (9)

Vanadium dioxide-containing particles having thermochromic properties,
An element A selected from group 2 of the periodic table and an element B selected from group 5 or 6 of the periodic table excluding vanadium,
The total content of the element A is in the range of 0.5 to 20 atom% and the total content of the element B is in the range of 0.05 to 20 atom% with respect to vanadium (100 atom%). Vanadium-containing particles. The element B is tungsten;
2. The vanadium dioxide-containing particles according to claim 1, wherein the tungsten content is in the range of 0.5 to 10 atom% with respect to vanadium (100 atom%). The element B is molybdenum;
The vanadium dioxide-containing particles according to claim 1 or 2, wherein the molybdenum content is in the range of 0.5 to 10 atom% with respect to vanadium (100 atom%). The element A is magnesium;
4. The vanadium dioxide-containing particles according to claim 1, wherein the magnesium content is in a range of 0.5 to 10 atom% with respect to vanadium (100 atom%).   The thermochromic film containing the vanadium dioxide containing particle | grains as described in any one of Claim 1- Claim 4. The thermochromic film according to claim 5, wherein a color difference ΔE ^* ab accompanying a temperature change from 15 ° C to 70 ° C satisfies the following formula (1).
4.0 ≦ ΔE ^* ab ≦ 6.5 (1) A method for producing vanadium dioxide-containing particles having thermochromic properties,
Preparing a reaction solution comprising a vanadium-containing compound, an element A selected from group 2 of the periodic table, an element B selected from group 5 or 6 of the periodic table excluding vanadium, and water;
Hydrothermal reaction of the reaction solution to form vanadium dioxide-containing particles;
Have
In the step of preparing the reaction solution, the total addition amount of the element A is within a range of 0.5 to 20 atom% with respect to vanadium (100 atom%), and the total addition amount of the element B is 0.05 to A method for producing vanadium dioxide-containing particles in a range of 20 atom%.   The method for producing vanadium dioxide-containing particles according to claim 7, wherein the vanadium-containing compound is a vanadium (IV) -containing compound.   9. The vanadium dioxide-containing composition according to claim 7, wherein in the step of forming the vanadium dioxide-containing particles, the hydrothermal reaction is performed within a liquid temperature range of 250 to 450 ° C. and a reaction time of 1 second to 48 hours. Particle production method.