WO2017006699A1

WO2017006699A1 - Vanadium dioxide-containing particles, dispersion liquid containing same, optical film containing same, method for producing same, method for producing said dispersion liquid, and method for producing said optical film

Info

Publication number: WO2017006699A1
Application number: PCT/JP2016/067282
Authority: WO
Inventors: ▲高▼向　保彦
Original assignee: コニカミノルタ株式会社
Priority date: 2015-07-09
Filing date: 2016-06-09
Publication date: 2017-01-12
Also published as: JPWO2017006699A1

Abstract

The present invention provides a means for improving thermochromic properties of vanadium dioxide-containing particles and transparency of an optical film that uses the vanadium dioxide-containing particles. The present invention provides a method for producing vanadium dioxide-containing particles, which comprises subjecting a reaction liquid that is obtained by mixing a starting material liquid containing a vanadium-containing compound and water and another starting material liquid containing water and a compound which is reactive with the vanadium-containing compound to a hydrothermal reaction in the presence of water in a subcritical or supercritical state.

Description

Vanadium dioxide-containing particles, dispersion liquid and optical film containing the same, and production method thereof

The present invention relates to vanadium dioxide-containing particles having excellent thermochromic properties, and a dispersion and an optical film containing the same. The present invention also relates to these production methods.

Energy saving and comfort in places where large heat exchange occurs between the interior (indoors, inside the vehicle) and the external environment, such as buildings such as houses and buildings, and vehicles such as vehicles (for example, window glass) Therefore, the application of thermochromic materials is expected.

“Thermochromic material” is a material whose optical properties such as transparency can be controlled by temperature. For example, when a thermochromic material is applied to a window glass of a building, it is possible to reflect infrared rays in summer when the temperature is high to block heat, and to transmit infrared rays in winter when the temperature is low. Become.

One of the thermochromic materials that are currently attracting the most attention is a material containing vanadium dioxide (VO ₂ ). It is known that vanadium dioxide exhibits thermochromic properties (property of reversibly changing optical properties depending on temperature, also referred to as “thermochromic property”) during a phase transition near room temperature. Therefore, a material exhibiting an ambient temperature-dependent thermochromic characteristic can be obtained by utilizing this characteristic.

Here, vanadium dioxide has several crystal phase polymorphs such as A phase, B phase, C phase and rutile crystal phase (hereinafter also referred to as “R phase”). Among these, the crystal structure showing the thermochromic characteristics as described above at a relatively low temperature of 100 ° C. or lower is limited to the R phase. The R phase has a monoclinic structure below the phase transition temperature (about 68 ° C.), and has high transmittance for visible light and infrared light. On the other hand, the R phase has a tetragonal structure above the phase transition temperature, and exhibits a property of low infrared transmittance as compared with a monoclinic structure.

When an optical film using such vanadium dioxide-containing particles is applied to a window glass or the like, transparency (having a small haze) is required, the vanadium dioxide-containing particles are not aggregated, and the particle diameter Is preferably nano-order (100 nm or less).

As a method for producing such vanadium dioxide-containing particles, a method for producing R-phase vanadium dioxide particles by a hydrothermal reaction has been reported.

For example, Japanese Patent Publication No. 2014-505651 discloses that the composition of a doping vanadium dioxide powder (V _1-x M _x O ₂ ) is such that the doping element is 0 <x ≦ 0.5. It is disclosed that the size and shape of the image can be controlled. In addition, this publication discloses that, as a result, the size of crystal grains of the manufactured doped vanadium dioxide powder can be reduced and made uniform. In this publication, as a method for producing such a doping vanadium dioxide powder, a reaction precursor treated so that a hydrothermal reaction can be performed more easily is transferred to a hydrothermal reaction autoclave to perform a hydrothermal reaction. Thereafter, a method for dry separation of the hydrothermal reaction product is disclosed.

However, sufficient transparency could not be obtained in the optical film using vanadium dioxide-containing particles by the technique disclosed in JP-T-2014-505651.

As a result of investigations, the present inventors have found that the vanadium dioxide-containing particles obtained by the production method disclosed in JP-T-2014-505651 are not sufficiently uniform in particle size, and a part of them is large. It has been found that a particle size component is included, thereby having a wide particle size distribution. And the present inventors discovered that the transparency of the optical film using this vanadium dioxide containing particle | grains falls because the particle diameter distribution of vanadium dioxide containing particle | grains spreads.

In addition, the technique disclosed in JP-A-2014-505651 requires that materials such as vanadium-containing compounds and compounds that react with vanadium-containing compounds used in the reaction be limited in order to obtain particles having a small average particle size. It was lacking in nature.

This invention is made | formed in view of the said subject, and it aims at providing the means which can improve the thermochromic property of vanadium dioxide containing particle | grains, and the transparency of the optical film using this vanadium dioxide containing particle | grain. .

In view of the above-mentioned problems, the present inventors proceeded with intensive studies. As a result, the inventors have found that the above problems can be solved by the following means, and have completed the present invention.

A reaction liquid obtained by mixing a raw material liquid containing a vanadium-containing compound and water and a raw material liquid containing a compound that reacts with the vanadium-containing compound and water is treated with water in the presence of subcritical or supercritical water. having thereby thermal reaction method of vanadium dioxide (VO ₂₎ containing particles.

Vanadium dioxide (VO ₂ ) -containing particles having an average particle diameter (D) of 60 nm or less and a polydispersity index (PDI) of less than 0.30.

It is the schematic which shows an example of the micro reactor type | mold flow-type reaction apparatus which concerns on one preferable form of this invention. Here, 1 is a microreactor type flow reactor, 2 and 5 are raw material liquid containers, 3, 6, and 11 are pipes, 4, 7, and 12 are pumps, and 8 is a cooling pipe. , 9, 10 are tanks, 13, 14 and 15 are heating media, 16 is a microreactor section, and TC is a temperature sensor.

Hereinafter, embodiments of the present invention will be described. In addition, this invention is not limited only to the following embodiment. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

In this specification, “X to Y” indicating a range means “X or more and Y or less”. Unless otherwise specified, operations and physical properties are measured under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50% RH.

Furthermore, in the present specification, the notation “(meth) acryl” in the specific names of the compounds represents “acryl” and “methacryl”, and “(meth) acrylate” represents “acrylate” and “methacrylate”. The “acrylic resin” refers to a resin having an acrylic acid ester, a methacrylic acid ester or a derivative thereof as a constituent component of the (co) polymer. The “acrylic resin” includes resins having other monomers as a constituent component of the copolymer in addition to the above monomers.

<Method for producing vanadium dioxide-containing particles>
The method for producing vanadium dioxide (VO ₂ ) -containing particles having thermochromic characteristics according to one aspect of the present invention includes a raw material liquid containing a vanadium-containing compound and water, a raw material liquid containing a compound that reacts with the vanadium-containing compound, and water. And a hydrothermal reaction of the reaction liquid obtained by mixing the two in the presence of subcritical or supercritical water. According to the production method of the present embodiment, means for improving the thermochromic properties of the vanadium dioxide-containing particles and the transparency of the optical film containing the vanadium dioxide-containing particles is provided.

The present inventors presume a mechanism that can solve the above problem by the method for producing vanadium dioxide-containing particles according to an embodiment of the present invention as follows.

In conventional methods for producing vanadium dioxide-containing particles, including JP 2014-505651, hydrothermal reaction is usually performed at a saturated vapor pressure at the reaction temperature. In a long-time hydrothermal reaction under such conditions, a portion of the precipitated vanadium dioxide microcrystals grows greatly. As a result, the manufactured vanadium dioxide-containing particles contain a component having a large particle size and have a wide particle size distribution. At this time, even if the average particle size of the vanadium dioxide-containing particles is reduced by using various known means, the vanadium dioxide-containing particles will contain some non-uniform particle size components. . In addition, since the scattering of visible light is promoted by the presence of some non-uniform particle size components, it is difficult to sufficiently improve the transparency of the optical film containing the vanadium dioxide-containing particles by the conventional method. It is.

In addition, regarding the technique of JP-T-2014-505651, in order to obtain particles having a small average particle diameter under such reaction conditions, the size and shape of the doping vanadium dioxide powder is obtained by doping a predetermined element. It was indispensable to control, and lacked versatility.

On the other hand, in the production method according to the present invention, a reaction liquid obtained by mixing a raw material liquid containing a vanadium-containing compound and water and a raw material liquid containing water and a compound that reacts with the vanadium-containing compound is subcritical. Alternatively, the hydrothermal reaction is performed in the presence of water in a supercritical state. Under such conditions, the detailed mechanism is unknown, but the crystal growth of the precipitated vanadium dioxide microcrystals is suppressed. Thus, the production method according to the present invention can sufficiently reduce the average particle size of the produced vanadium dioxide-containing particles, and can significantly reduce the abundance of components having a large particle size. Furthermore, the manufactured vanadium dioxide-containing particles can achieve both a narrow particle size distribution. Such vanadium dioxide-containing particles can have high thermochromic properties due to the large surface area obtained by reducing the particle size, and have an optical functional layer containing such vanadium dioxide-containing particles. The optical film can obtain high transparency resulting from low visible light scattering due to small particle size and uniformity of particle size.

In addition, in order to obtain such an effect, the present invention does not necessarily dope a predetermined doping element as in the technique disclosed in JP-T-2014-505651. This is because the mechanism of the present invention is essentially different from the technique of Japanese Patent Application Laid-Open No. 2014-505651 which controls the size and shape of the doped vanadium dioxide powder by doping a predetermined element. That is, the production method according to the present invention is not only characterized by controlling the particle size and particle size distribution by the raw material forming the vanadium dioxide-containing particles, but mainly by reducing the particle size by hydrothermal reaction conditions. This is because a narrow particle size distribution is achieved. Thus, the manufacturing method according to the present invention is excellent in versatility, unlike the technique disclosed in JP-T-2014-505651.

Note that the above mechanism is speculative and does not limit the technical scope of the present invention.

In the present specification, “vanadium dioxide (VO ₂ ) -containing particles” refers to “vanadium dioxide-containing particles of the present invention” or “VO ₂ -containing particles of the present invention” or simply “vanadium dioxide-containing particles” or “VO ₂ -containing particles”. Also called.

Further, in this specification, “vanadium dioxide (VO ₂ ) -containing particles having thermochromic properties” means a transmittance difference (ΔT) (%) under specific conditions used as an evaluation of thermochromic properties in Examples described later. ) Means vanadium dioxide-containing particles having a content of 20% or more.

In the present specification, a reaction liquid obtained by mixing a raw material liquid containing a vanadium-containing compound and water and a raw material liquid containing a compound that reacts with the vanadium-containing compound and water is subcritical or supercritical. The hydrothermal reaction in the presence of water is also referred to as a “hydrothermal reaction step”.

(A) Hydrothermal reaction step In this step, a reaction liquid obtained by mixing a raw material liquid containing a vanadium-containing compound and water and a raw material liquid containing a compound that reacts with the vanadium-containing compound and water is subcritical. Alternatively, a hydrothermal reaction is performed in the presence of supercritical water. By this step, vanadium dioxide-containing particles are obtained.

The vanadium-containing compound (a raw material of vanadium dioxide-containing particles) is not particularly limited, vanadium pentoxide _(V) (V _{2 O} 5), ammonium vanadate _(V) (NH 4 _VO 3), Vanadium Oxytrichloride (V) (VOCl ₃ ), sodium vanadate (V) (NaVO ₃ ), vanadyl oxalate (IV) (VOC ₂ O ₄ ), vanadium oxide sulfate (hereinafter also referred to as vanadyl sulfate) (IV) (VOSO ₄ ) Examples thereof include those obtained by dissolving divanadium tetroxide (IV) (V ₂ O ₄ ) or the like with an acid such as sulfuric acid. In addition, said vanadium containing compound may be melt | dissolved in the reaction liquid, and may be disperse | distributed. Moreover, a vanadium containing compound may be used individually by 1 type, or may mix and use 2 or more types. These compounds may be hydrated (hydrate).

The compound that reacts with the vanadium-containing compound is not particularly limited as long as it can produce vanadium dioxide-containing particles by hydrothermal reaction of the reaction solution, and examples thereof include alkalis and reducing agents.

Here, the hydrothermal reaction is
(A-1) The vanadium-containing compound is a vanadium (IV) -containing compound, and the compound that reacts with the vanadium-containing compound is performed in a reaction solution containing at least one alkali (hereinafter, also referred to as method 1), or (A-2) The vanadium-containing compound is a vanadium (V) -containing compound, and the compound that reacts with the vanadium-containing compound is carried out in a reaction solution containing a reducing agent (for example, hydrazine and hydrates thereof) ( Hereinafter, also referred to as method 2),
Is preferred.

(A-1) Method 1
In the above (a-1), the vanadium (IV) -containing compound (the raw material for the vanadium dioxide-containing particles) is not particularly limited, and can be appropriately selected from those described above. Among these, vanadium oxide (IV) sulfate (VOSO ₄ ) is preferable from the viewpoint that a by-product is not generated as much as possible after the hydrothermal reaction. In addition, a vanadium (IV) containing compound may be used individually by 1 type, or may mix and use 2 or more types.

The initial concentration of the vanadium (IV) -containing compound contained in the reaction solution obtained by mixing each raw material solution is not particularly limited as long as the effect of the present invention is obtained, but is preferably 0.1 to 1000 mmol / L. is there. With such a concentration, the vanadium (IV) -containing compound is sufficiently dissolved or dispersed, the average particle size (particle size) of the obtained vanadium dioxide-containing particles is reduced, and the particle size (particle size) distribution is narrow ( By lowering the polydispersity index), the thermochromic properties of the vanadium dioxide-containing particles and the transparency of the optical film containing the vanadium dioxide-containing particles can be further increased. The initial concentration of the vanadium (IV) compound contained in the reaction solution is the average particle size and particle size distribution of the vanadium dioxide-containing particles, that is, the thermochromic properties of the vanadium dioxide-containing particles, and the transparency of the optical film containing the vanadium dioxide-containing particles. In view of the above, it is more preferably 20 to 600 mmol / L, still more preferably 50 to 400 mmol / L. In addition, said "initial concentration" is the amount of vanadium (IV) -containing compounds in 1 L of the reaction solution before hydrothermal reaction (the total amount when two or more vanadium (IV) -containing compounds are included). is there.

As described in (a-1) above, the compound that reacts with the vanadium-containing compound that can be used together with the vanadium (IV) -containing compound is preferably an alkali. That is, the hydrothermal reaction is preferably performed in a reaction solution in which the vanadium-containing compound is a vanadium (IV) -containing compound and the compound that reacts with the vanadium-containing compound contains at least one alkali. Furthermore, it is more preferable that the compound that reacts with the vanadium-containing compound consists only of alkali. In the present specification, an alkali means a substance that generates hydroxide ions (OH ⁻ ) in an aqueous solution, and is not only a compound that is ionized to generate hydroxide ions, but also a compound itself. Are not ionized to produce hydroxide ions, but those that eventually produce hydroxide ions are also included.

Examples of the alkali include, but are not limited to, ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate. The said alkali can be used individually by 1 type or in combination of 2 or more types.

Among these, the alkali is preferably ammonia, sodium hydroxide, or potassium hydroxide, more preferably ammonia or sodium hydroxide, and even more preferably ammonia.

The amount of alkali in the raw material liquid containing alkali and water is not particularly limited, but is preferably 0.01 to 10 mol / L, more preferably 0.1 to 5 mol / L, for example, 0 More preferably, it is 3 to 3 mol / L.

Here, the amount of alkali in the reaction liquid obtained by mixing each raw material liquid is not particularly limited, but includes, for example, a raw material liquid containing a vanadium-containing compound and water, a compound that reacts with the vanadium-containing compound, and water. It is preferable to add an amount such that the pH of the reaction liquid obtained by mixing the raw material liquid is 6.0 to 8.0, and it is more preferable to add an amount that is 6.5 to 7.5. It is more preferable to add an amount of 6.8 to 7.2, and it is particularly preferable to add an amount of 6.9 to 7.1.

(A-2) Method 2
In the above (a-2), the vanadium (V) -containing compound (the raw material for the vanadium dioxide-containing particles) is not particularly limited, and can be appropriately selected from those described above. Among these, from the viewpoint of not generating by-products as much as possible after the hydrothermal reaction, divanadium pentoxide, ammonium vanadate (NH ₄ VO ₃ ), or vanadium trichloride oxide is preferable. From the same viewpoint, the vanadium (V) -containing compound is more preferably divanadium pentoxide and ammonium vanadate, and particularly preferably ammonium vanadate (NH ₄ VO ₃ ). In addition, the said vanadium (V) containing compound may be used individually by 1 type, or may mix and use 2 or more types.

The initial concentration of the vanadium (V) -containing compound contained in the reaction solution is not particularly limited as long as the objective effect of the present invention can be obtained, but is preferably 0.1 to 1000 mmol / L. At such a concentration, the reducing agent acts efficiently, and the particle size of the resulting vanadium dioxide-containing particles is reduced, and the particle size distribution is narrowed (low polydispersity index), and thermochromic properties are further improved. Can be increased. The initial concentration of the vanadium (V) compound contained in the reaction solution is such as the particle size and particle size distribution of the vanadium dioxide-containing particles, that is, the thermochromic properties of the vanadium dioxide-containing particles and the transparency of the optical film containing the vanadium dioxide-containing particles. From the viewpoint, it is more preferably 20 to 600 mmol / L, and further preferably 50 to 400 mmol / L. In addition, said "initial concentration" is the amount of vanadium (V) containing compounds in 1 L of reaction liquid before the hydrothermal reaction (the total amount when two or more vanadium (V) containing compounds are included). is there.

Moreover, it is preferable that the compound which reacts with the vanadium containing compound which can be used with a vanadium (V) containing compound is a reducing agent. Examples of the reducing agent include oxalic acid and its hydrate, hydrazine (N ₂ H ₄ ) and its hydrate (N ₂ H ₄ .H ₂ O), water-soluble vitamins such as ascorbic acid, and derivatives thereof, Examples include sodium erythorbate, BHT (dibutylhydroxytoluene), BHA (butylhydroxyanisole), antioxidants such as propyl gallate and sodium sulfite, and reducing sugars such as glucose, fructose, glyceraldehyde, lactose and maltose. The said reducing agent can be used individually by 1 type or in combination of 2 or more types.

Of these, hydrazine or a hydrate thereof is preferable as the reducing agent. That is, the hydrothermal reaction is preferably performed in a reaction solution in which the vanadium-containing compound is a vanadium (V) -containing compound and the compound that reacts with the vanadium-containing compound contains at least one of hydrazine and its hydrate. Furthermore, the compound that reacts with the vanadium-containing compound is preferably only one selected from hydrazine and hydrates thereof, and more preferably only hydrazine hydrate.

Here, the amount of the reducing agent in the reaction liquid obtained by mixing each raw material liquid is added to the vanadium (V) -containing compound in an equimolar amount or more in consideration of the pH during the reaction and the amount decomposed during the reaction. It is preferable to do. For example, it is more preferably about 1.01-1.50 mol, and further preferably 1.05-1.30 mol with respect to 1 mol of the vanadium (V) -containing compound.

When vanadium pentoxide (V) (V ₂ O ₅ ) is used as the vanadium-containing compound, it is preferable to perform pretreatment in the presence of hydrogen peroxide before the hydrothermal reaction. By adding hydrogen peroxide, the vanadium-containing compound can be uniformly dissolved. Alternatively, the vanadium-containing compound may be pretreated in the presence of hydrogen peroxide and a reducing agent before the hydrothermal reaction. When a reduction reaction using a reducing agent is employed after a pretreatment with hydrogen peroxide, hydrogen peroxide and a reducing agent are sequentially added, for example, at 20 to 40 ° C., with stirring as necessary, for 0.5 to 10 The reaction can be performed for about an hour.

The pH of the reaction liquid obtained by mixing the raw material liquids varies depending on the vanadium (V) -containing compound used, and is preferably adjusted by the amount of reducing agent added. For example, when ammonium vanadate (NH ₄ VO ₃ ) is used as the vanadium (V) -containing compound, the reducing agent is preferably added in an amount such that the pH is 8.0 to 11.0. More preferably, the amount is from 0.0 to 10.0. In addition, for example, in the case of vanadium pentoxide or vanadium trichloride as the vanadium (V) -containing compound, the reducing agent is preferably added in such an amount that the pH is 3.5 to 5.5. It is more preferable to add an amount such that becomes 4.0 to 5.0.

The water in the raw material liquid containing the vanadium-containing compound and water, and the water in the raw material liquid containing the compound reacting with the vanadium-containing compound and the water are used as a dispersion medium or solvent for the vanadium-containing compound and the compound reacting with the vanadium-containing compound, respectively. It has a function. The reaction liquid obtained by mixing each raw material liquid also contains water as a solvent or a dispersion medium.

Water contained in these raw material liquids preferably has few impurities, and is not particularly limited. For example, distilled water, ion exchange water, pure water, ultrapure water, and water treated with nitrogen (N ₂ ) nanobubbles. Etc. are preferably used, and water treated with nitrogen (N ₂ ) nanobubbles is more preferably used.

Similarly, the water contained in the reaction solution is preferably one having few impurities, and is not particularly limited. For example, distilled water, ion exchange water, pure water, ultrapure water, nitrogen (N ₂ ) nanobubble treatment It is preferable to use water or the like. Here, the water in the reaction solution is more preferably nitrogen (N ₂ ) nanobubble-treated water.

Here, nitrogen (N ₂ ) nanobubble-treated water (N ₂ nanobubble-treated water) is prepared by mixing (bubbling) nitrogen in water. The use of water treated with nitrogen (N ₂ ) nanobubbles can reduce the dissolved oxygen concentration of the water, so that the obtained vanadium dioxide-containing particles can be suppressed / prevented from being oxidized again. The use of nitrogen (N ₂₎ nano bubbles treated water, and a smaller particle size of the resulting vanadium dioxide-containing particles, and can be a particle diameter distribution narrower (smaller polydispersity index). Here, the dissolved oxygen concentration of the water treated with nitrogen (N ₂ ) nanobubbles is not particularly limited, but is preferably 2 mg / L or less, more preferably 1 mg / L or less (lower limit: 0 mg / L).

Here, when the water contained in the reaction liquid is water that has been subjected to nitrogen (N ₂ ) nanobubble treatment, water contained in the raw material liquid containing the vanadium-containing compound and water, or a compound that reacts with the vanadium-containing compound and water are included. It is preferable that at least one of the water contained in the raw material liquid is nitrogen (N ₂ ) nanobubble-treated water, so that the water contained in the reaction solution is nitrogen (N ₂ ) nanobubble-treated water. Further, both the water contained in the raw material liquid, nitrogen (N ₂₎ by a nanobubbles treated water, water contained in the reaction liquid nitrogen (N ₂₎ nano bubbles treated to become still more water preferable.

In addition, the condition that the water contained in the reaction solution is nitrogen (N ₂ ) nanobubble-treated water is obtained by mixing the raw material solution containing the vanadium-containing compound and water, and the raw material solution containing the vanadium-containing compound and water. Alternatively, it may be achieved by performing nitrogen (N ₂ ) nanobubble treatment on water in the reaction solution.

As a production method according to an embodiment of the present invention, the reaction solution further includes a substance containing an element for adjusting the phase transition temperature of the vanadium dioxide-containing particles.

Here, the method for adding a substance containing an element for adjusting the phase transition temperature of the vanadium dioxide-containing particles (phase transition modifier) to the reaction solution is not particularly limited, and a known method can be used. As a method for adding to the reaction solution, it is preferable to add the reaction solution by adding it to a raw material solution containing a vanadium-containing compound and water. Moreover, the method of adding directly to the reaction liquid before a hydrothermal reaction can also be used.

Here, the phase transition regulator is not particularly limited, but tungsten, titanium, molybdenum, niobium, tantalum, tin, rhenium, iridium, osmium, ruthenium, germanium, chromium, iron, gallium, aluminum, fluorine, phosphorus, etc. Substances containing elements other than vanadium can be used. When the reaction liquid contains the phase change regulator, the phase transition temperature of the obtained vanadium dioxide-containing particles can be lowered. Here, the addition amount of the phase transition modifier is not particularly limited, but the element ratio (atomic ratio) of vanadium contained in the vanadium-containing compound to other elements contained in the phase transition modifier is 50.0: 50. Is preferably 0.0 to 99.9: 0.1, more preferably 70.0: 30.0 to 99.5: 0.5, and 80.0: 20.0 to 99.5: 0.5 is more preferable, and 90.0: 10.0 to 99.5: 0.5 is particularly preferable. Moreover, the form of the phase transition regulator is not particularly limited, and examples thereof include oxides and ammonium salts of the other elements. Here, the phase Examples of transition modulators may include, for example, ammonium tungstate para pentahydrate _{_{_{_{((NH 4) 10 W 12}}}} O 41 · 5H 2 O) and the like.

In this step, the reaction solution is hydrothermally reacted to form vanadium dioxide-containing particles. The “hydrothermal reaction” means a mineral synthesis or alteration reaction, that is, a chemical reaction performed in the presence of high-temperature water, particularly high-temperature and high-pressure water.

The hydrothermal reaction in the present invention is carried out in a state where the temperature is 150 ° C. or higher and the pressure is higher than the saturated vapor pressure, that is, water is present in a subcritical or supercritical state. Features. It is known that by performing the reaction under such conditions, a unique reaction can occur at high pressure due to the presence of water, unlike the case of high pressure at normal pressure. It is also known that the solubility of oxides such as silica and alumina is improved and the reaction rate is improved.

In the present invention, by performing the hydrothermal reaction under such conditions, the average particle size (D) of the vanadium dioxide-containing particles formed by the hydrothermal reaction, and the polydispersity index (PDI) representing the particle size distribution The value can be reduced, and the thermochromic property of the vanadium dioxide-containing particles and the transparency of the optical film containing the vanadium dioxide-containing particles can be improved.

Although the detailed mechanism is unknown, these excellent effects are presumed to be achieved by suppressing the crystal growth of precipitated vanadium dioxide microcrystals by hydrothermal reaction under such conditions. .

Hydrothermal reaction conditions are not particularly limited as long as the temperature at which water is present in a subcritical or supercritical state is 150 ° C. or higher and the pressure is higher than the saturated vapor pressure, and other conditions ( For example, it can be appropriately set according to the amount of reactant, reaction temperature, reaction pressure, reaction time, and the like.

Here, the saturated water vapor pressures at 150 ° C., 250 ° C., 270 ° C., and 350 ° C. are 0.48 MPa, 3.98 MPa, 5.51 MPa, and 16.54 MPa, respectively. In addition, when the temperature is 374.15 ° C. or higher and the pressure is 22.12 MPa or higher, the water is in a supercritical state.

The hydrothermal reaction conditions are not particularly limited as long as the temperature and pressure are 150 ° C. or higher as described above and the pressure is higher than the saturated vapor pressure, but the temperature is 270 ° C. to 450 ° C. More preferably, the temperature is 10 ° C., the pressure is 10 to 40 MPa, and the pressure is higher than the saturated vapor pressure at the set temperature. When the temperature is 270 ° C. or higher, the average particle diameter (D) and the polydispersity index (PDI) can be further reduced. Moreover, an average particle diameter (D) will have a more suitable magnitude | size as temperature is 450 degrees C or less, and thermochromic property improves more. From the same viewpoint, it is more preferable that the temperature is 350 to 450 ° C., the pressure is 20 to 40 MPa, and the pressure is higher than the saturated vapor pressure at the set temperature, and the temperature is 380 to 400 ° C. It is particularly preferable to conduct the hydrothermal reaction in the presence of supercritical water at a pressure of 25 to 30 MPa.

The hydrothermal reaction time is not particularly limited, but is preferably 0.01 seconds to 48 hours. Under these conditions, vanadium dioxide-containing particles having a narrow particle size distribution and a small particle size can be produced more efficiently. Moreover, possibility that the crystallinity of vanadium dioxide containing particle | grains becomes low can be reduced more. The hydrothermal reaction may be performed in one stage using the same conditions, or may be performed in multiple stages by changing the conditions.

The hydrothermal reaction may be performed while stirring. By stirring, vanadium dioxide-containing particles can be more uniformly prepared. Further, the hydrothermal reaction may be carried out in a batch manner or a continuous manner (circulation manner).

The hydrothermal reaction can be carried out using an apparatus such as a high-pressure reaction decomposition vessel, an autoclave, a test tube type reaction vessel, a microreactor type flow reactor, or the like.

Among these, it is more preferable to use a microreactor type flow reactor.

Thus, a preferred embodiment of the present invention is a production method in which the hydrothermal reaction is performed using a microreactor type flow reactor.

Hereinafter, a preferred embodiment in which a hydrothermal reaction is performed using a microreactor type flow reactor will be described. In addition, this invention is not limited to the following form.

The microreactor type flow reactor is a flow reactor equipped with a microreactor.

Here, the microreactor is intended to be a mixing and reactor that utilizes a small space to realize high-speed mixing and reaction.

Using a microreactor, the hydrothermal reaction is carried out under high pressure in the presence of subcritical or supercritical water, so that the average particle size (D) of the vanadium dioxide-containing particles and the polydispersity index (PDI) The value can be made extremely small, and particularly excellent thermochromic properties of vanadium dioxide-containing particles and transparency of optical films containing vanadium dioxide-containing particles can be achieved. This is because the hydrothermal reaction is carried out in the presence of subcritical or supercritical water under high pressure, so that the liquid mixing and reaction can be completed in a very short time, and the precipitated vanadium dioxide microcrystals are formed. It is presumed that sufficient time for large crystal growth is not given.

When the hydrothermal reaction is performed using a microreactor type flow reactor, the hydrothermal reaction time is preferably 0.01 seconds to 10 seconds. When it is 0.01 seconds or longer, vanadium dioxide-containing particles can be more reliably formed. If it is 10 seconds or less, the polydispersity index (PDI) tends to be smaller. From the same viewpoint, the time is more preferably 0.1 to 5 seconds.

Fig. 1 shows a specific structural example of a microreactor type flow reactor. FIG. 1 is a schematic view showing a microreactor type flow reactor according to a preferred embodiment of the present invention. In FIG. 1, a microreactor type flow reactor 1 includes a raw material liquid container (tank) 2 and a raw material liquid container (tank) 5 for containing a raw material liquid, and a part including a microreactor having a heating medium 14 that performs a hydrothermal reaction. The microreactor section 16, the tank 9 for containing the reaction solution after the hydrothermal reaction, the raw material liquid container 2 and the raw material liquid container 5, and the flow paths (piping) 3 and 6, respectively connecting the tank 9, A pump 4 for circulating the raw material liquid, the reaction liquid and the reaction liquid after the hydrothermal reaction from the raw material liquid container 2 to the tank 9 via the pipe 3, and the raw material liquid via the pipe 6 from the raw material liquid container 5 to the tank 9; A pump 7 is provided for circulating the reaction solution and the reaction solution after the hydrothermal reaction.

If necessary, the microreactor type flow reactor 1 may include a cooling pipe 8 for further cooling the reaction liquid after the hydrothermal reaction, as shown in FIG. In addition, as will be described later, as shown in FIG. 1, if necessary, it is mixed with the surface modifier, the pH adjuster or the reaction solution after the hydrothermal reaction to be cooled by being added to the reaction solution after the hydrothermal reaction. The tank 10 for containing the cooling medium (for example, water), the surface modifier, the pH adjuster, or the pump 12 for circulating the cooling medium through the pipe 11 may be further included. Further, if necessary, the microreactor type distribution device 1 may further include heating media 13 and 15 as shown in FIG.

The material of the microreactor section 16 through which the raw material liquid, the reaction liquid or the reaction liquid after the hydrothermal reaction flows and the flow paths such as the

pipes

3, 6, 11 are not particularly limited, but stainless steel, aluminum, iron, Hastelloy and the like can be mentioned. The length of the flow path is not particularly limited, but is preferably 50 to 10,000 mm, more preferably 100 to 1,000 mm. Further, the gap (inner diameter in the case of piping) of the flow path is not particularly limited, but is preferably 0.001 to 10 mm, more preferably 0.005 to 2 mm. With such a material and shape, the hydrothermal reaction can be effectively carried out at a predetermined speed.

The

pipes

3, 6 and 11 preferably have the above material, length and inner diameter, but may be the same or different.

Further, the speed (circulation speed) at which the reaction liquid passes through (flows through) the microreactor section is not particularly limited, but is preferably 0.01 to 10 mL / second, more preferably 0.1 to 5 mL / second. is there. With such a distribution speed, the hydrothermal reaction can be effectively carried out under predetermined conditions.

The reaction liquid after the hydrothermal reaction obtained by the (a) hydrothermal reaction step is replaced with a dispersion medium or a solvent by filtration (for example, ultrafiltration) or centrifugal separation, and the vanadium dioxide-containing particles are exchanged with water or You may wash | clean with alcohol (for example, ethanol) etc. The obtained vanadium dioxide-containing particles may be dried by any means.

As a production method according to an embodiment of the present invention, it is preferable to add a surface modifier immediately after the hydrothermal reaction.

By using a surface modifier, the aggregation of vanadium dioxide-containing particles is effectively suppressed / prevented, the size (particle diameter) of vanadium dioxide-containing particles is reduced, the particle size distribution is narrowed, and vanadium dioxide is contained. The dispersion stability and storage stability of the particles can be further improved. Therefore, the haze of the vanadium dioxide-containing particles can be reduced more effectively, and the thermochromic properties can be improved more effectively.

Here, examples of the surface modifier include organic silicon compounds, organic titanium compounds, organic aluminum compounds, organic zirconia compounds, surfactants, silicone oils, and the like. The number of reactive groups in the surface modifier is not particularly limited, but is preferably 1 or 2.

Specifically, as an organosilicon compound (organic silicate compound) used as a surface modifier, for example, hexamethyldisilazane, trimethylethoxysilane, trimethylmethoxysilane, tetraethoxysilane (tetraethyl orthosilicate), trimethylsilyl chloride, methyl Triethoxysilane, dimethyldiethoxysilane, decyltrimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltri Ethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, - glycidoxypropyl methyldimethoxysilane, and the like. Moreover, as a commercially available thing, SZ6187 (made by Toray Dow Silicone Co., Ltd.) etc. can be used conveniently, for example. Among these, it is preferable to use an organic silicate compound having a low molecular weight and high durability, more preferably hexamethyldisilazane, tetraethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, and trimethylsilyl chloride. More preferably, silane is used.

Examples of the organic titanium compound include tetrabutyl titanate, tetraoctyl titanate, tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, isopropyl triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, bis (dioctyl pyrophosphate) oxy Acetate titanate, etc., and chelate compounds such as titanium acetylacetonate, titanium tetraacetylacetonate, titanium ethylacetoacetate, titanium phosphate compound, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium triethanolaminate, etc. Is mentioned. Examples of commercially available products include Prenact (registered trademark) TTS (manufactured by Ajinomoto Fine Techno Co., Ltd.), Preneact (registered trademark) TTS44 (manufactured by Ajinomoto Fine Techno Co., Ltd.), and the like.

Examples of the organoaluminum compound include aluminum isopropoxide, aluminum tert-butoxide and the like.

Examples of the organic zirconia compound include normal propyl zirconate, normal butyl zirconate, zirconium monoacetylacetonate, zirconium tetraacetylacetonate and the like.

The surfactant is a compound having a hydrophilic group and a hydrophobic group in the same molecule. Specific examples of the hydrophilic group of the surfactant include a hydroxy group, a hydroxyalkyl group having 1 or more carbon atoms, a hydroxyl group, a carbonyl group, an ester group, an amino group, an amide group, an ammonium salt, a thiol, a sulfonate, A phosphate, a polyalkylene glycol group, etc. are mentioned. Here, the amino group may be primary, secondary, or tertiary. Specific examples of the hydrophobic group of the surfactant include an alkyl group, a silyl group having an alkyl group, and a fluoroalkyl group. Here, the alkyl group may have an aromatic ring as a substituent. The surfactant only needs to have at least one hydrophilic group and one hydrophobic group as described above in the same molecule, and may have two or more groups. More specifically, as the surfactant, myristyl diethanolamine, 2-hydroxyethyl-2-hydroxydodecylamine, 2-hydroxyethyl-2-hydroxytridecylamine, 2-hydroxyethyl-2-hydroxytetra Decylamine, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, di-2-hydroxyethyl-2-hydroxydodecylamine, alkyl (8 to 18 carbon atoms) benzyldimethylammonium chloride, ethylenebisalkyl (C8-18) Amide, stearyl diethanolamide, lauryl diethanolamide, myristyl diethanolamide, palmityl diethanolamide, perfluoroalkenyl, perf Oroarukiru compounds.

Examples of the silicone oil include straight silicone oil such as dimethyl silicone oil, methylphenyl silicone oil, and methylhydrogen silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, carrubinol-modified silicone oil, and methacryl-modified. Silicone oil, mercapto modified silicone oil, heterogeneous functional group modified silicone oil, polyether modified silicone oil, methylstyryl modified silicone oil, hydrophilic special modified silicone oil, higher alkoxy modified silicone oil, higher fatty acid-containing modified silicone oil and fluorine modified silicone And modified silicone oils.

It is preferable that the surface modifier is appropriately diluted with hexane, toluene, methanol, ethanol, acetone, water or the like and mixed with the reaction solution after the hydrothermal reaction in the form of a solution. The number of carbon atoms in the organic functional group introduced by the surface modifier is preferably 1-6. Thereby, durability can be improved. Further, the solution containing the surface modifier may be adjusted to an appropriate pH value (for example, 2 to 12) using a pH adjuster. Here, it does not restrict | limit especially as a pH adjuster, The thing similar to the below-mentioned pH adjuster can be used.

The addition amount of the surface modifier in the case of using the surface modifier is not particularly limited, but is preferably 0.1 to 100% by mass with respect to the mass of the vanadium dioxide-containing particles obtained by the hydrothermal reaction. The content is more preferably 1 to 10% by mass, and further preferably 1 to 5% by mass.

The addition of the surface modifier is preferably started immediately after the hydrothermal reaction (immediately after the end of the reaction) from the viewpoint of modifying the particle surface. Specifically, the addition is preferably performed within 10 seconds from the end of the reaction, and more preferably within 5 seconds.

The method for adding the surface modifier is not particularly limited, and a known method can be used. For example, when the microreactor type flow reactor 1 shown in FIG. 1 is used, a surface modifier (or a solution containing the surface modifier) is supplied from the tank 10 to the pump 12 with respect to the reaction liquid immediately after the hydrothermal reaction. Can be mixed by flowing through the pipe 11.

The speed at which the solution containing the surface modifier passes (circulates) through the pipe (circulation speed) is not particularly limited, but is preferably 0.01 to 10 mL / second, more preferably 0.1 to 5 mL / second. At such a distribution speed, the surface modifier and the vanadium dioxide-containing particles are sufficiently brought into contact with each other, and since the ratio of the organic portion is small, the effect of the surface modifier (inhibition of particle aggregation) is maintained while ensuring durability. Effect, dispersion stability and storage stability) can be exhibited sufficiently effectively.

The mixing position of the reaction solution after the hydrothermal reaction and the surface modifier (the installation position of the pipe 11) is not particularly limited, but in order to start adding the surface modifier immediately after the hydrothermal reaction, It is preferable to arrange it immediately after. Further, when the cooling pipe 8 is provided after the microreactor section 16 as in the microreactor type flow reactor 1, it is preferable to arrange the cooling pipe 8 immediately after the microreactor section 16 and before the cooling pipe 8.

In addition, when using the below-mentioned pH adjuster or the cooling medium in a below-mentioned cooling process with a surface modifier, necessary equipment, such as the tank 10, the piping 11, and the pump 12, may be provided individually corresponding to each. Good. In addition, in the case of using a mixture of a surface modifier and a pH adjuster, a surface modifier and a cooling medium, or a surface modifier, a pH adjuster and a cooling medium, one facility is used for a mixture of these. May be used to simultaneously realize the functions of

Here, in this specification, the addition of the surface modifier immediately after the hydrothermal reaction, that is, the addition of the surface modifier performed before the (b) cooling step described later is included in the (a) hydrothermal reaction step. Shall be handled.

As a production method according to an embodiment of the present invention, a pH adjuster may be further added after the hydrothermal reaction.

The pH adjuster is not particularly limited, but for example, an organic or inorganic acid or alkali such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, oxalic acid (including hydrate), ammonium hydroxide, ammonia or the like is used. it can.

From the viewpoint of the particle size and particle size distribution of the vanadium dioxide-containing particles, the thermochromic properties of the vanadium dioxide-containing particles, and the transparency of the optical film containing the vanadium dioxide-containing particles, the pH of the reaction solution after the hydrothermal reaction is, for example, 3 It is preferably from 0.0 to 9.0, more preferably from 4.0 to 7.0. From this, it is preferable that the pH of the reaction liquid after adding the pH adjuster after the hydrothermal reaction is within the above range. The pH adjusting agent may be the same as or different from the alkali and reducing agent used as the compound that reacts with the vanadium-containing compound in the hydrothermal reaction.

It is preferable that the pH adjusting agent is appropriately diluted with methanol, ethanol, water or the like and mixed with the reaction solution after the hydrothermal reaction in the form of a solution.

The method for adding the pH adjuster is not particularly limited, and a known method can be used. For example, when the microreactor type flow reactor 1 shown in FIG. 1 is used, a pH adjusting agent (or a solution containing the pH adjusting agent) is supplied from the tank 10 to the pump 12 with respect to the reaction solution immediately after the hydrothermal reaction. Can be mixed by flowing through the pipe 11.

The mixing position of the reaction solution after the hydrothermal reaction and the pH adjusting agent (installation position of the pipe 11) is not particularly limited, but in order to start the addition of the surface modifier after the hydrothermal reaction, the microreactor section 16 It is preferable to arrange. Further, in the case of having the cooling pipe 8 after the microreactor section 16 as in the microreactor type flow reactor 1, it may be arranged after the microreactor section 16 and before the cooling pipe 8, It may be arranged after the cooling pipe 8 and before the tank 9.

In addition, when using the above-mentioned surface modifier or the cooling medium in the cooling process described later together with the pH adjuster, necessary equipment such as the tank 10, the pipe 11 and the pump 12 may be individually provided in a corresponding manner. Good. Further, in the case of using a pH adjuster and a surface modifier, a pH adjuster and a cooling medium, or a mixture of a pH adjuster, a surface modifier and a cooling medium, as described in the description of the surface modifier above, For a mixture of these, one facility may be used to simultaneously realize a plurality of functions.

Moreover, when addition of a pH adjuster is performed before the below-mentioned (b) cooling process, these addition shall be contained in (a) hydrothermal reaction process, and after the below-mentioned (b) cooling process (B) It shall be included in a cooling process.

(B) Cooling step In addition to the (a) hydrothermal reaction step, the production method according to one embodiment of the present invention includes a reaction solution after the hydrothermal reaction (containing vanadium dioxide obtained in the above (a) hydrothermal reaction step). It is preferable to further have a cooling step for cooling the dispersion liquid containing particles).

In the cooling step, it is preferable to start cooling the reaction liquid after the hydrothermal reaction within 1 minute after the hydrothermal reaction is performed for a predetermined time (at the end of the reaction), but the entire reaction liquid is cooled within this time. If this is difficult, the reaction solution may be cooled sequentially by a predetermined amount while maintaining the reaction temperature at the reaction temperature with a wide reaction time.

In this step, the cooling rate can be adjusted as appropriate.

The method for cooling the reaction solution after the hydrothermal reaction is not particularly limited, and a known method can be applied in the same manner or appropriately modified. As a cooling method, for example, a reaction solution after hydrothermal reaction is immersed in a cooling medium while stirring, if necessary, and a reaction liquid after hydrothermal reaction is mixed with a cooling medium (especially water). Examples thereof include a method and a method in which a gaseous cooling medium (for example, liquid nitrogen) is passed through the reaction solution after the hydrothermal reaction. Among these, the method of mixing the reaction liquid after the hydrothermal reaction and the cooling medium is preferable because the cooling rate can be easily controlled. Here, at least the cooling is preferably performed in the microreactor type flow reactor using a cooling pipe connected to the microreactor unit directly or via other components.

In the microreactor type flow reactor, a cooling method using a cooling pipe connected to the microreactor unit directly or via other components will be described. In addition, the cooling method which can be used for this invention is not limited to the following method.

As a cooling method, the reaction liquid after the hydrothermal reaction is cooled by passing (circulating) the flow path of the microreactor type flow reactor. In other words, taking the microreactor type flow reactor 1 of FIG. 1 as an example, cooling is performed by passing (circulating) the flow path after the microreactor section 16. Here, the microreactor type flow reactor 1 may further include a cooling pipe 8 for further cooling the reaction liquid after the hydrothermal reaction, as shown in FIG.

In addition, as another cooling method, for the purpose of mixing and cooling the reaction liquid after the hydrothermal reaction and the cooling medium, the necessary equipment such as the tank 10 is circulated as described above. It may be a method used for the purpose. At this time, the equipment used for the cooling method may further include a pump 12 for circulating the cooling medium through the pipe 11.

In this case, as the cooling medium, a cooling medium having a pH adjusting effect obtained by adding a pH adjusting agent may be used.

When using a cooling medium, the mixing ratio of the cooling medium with the reaction liquid after the hydrothermal reaction is not particularly limited as long as a desired cooling rate can be achieved. For example, it is preferable to mix the cooling medium at a ratio of 1 to 2000 times (volume ratio), more preferably 10 to 1000 times (volume ratio) compared to the reaction liquid after the hydrothermal reaction. The mixing ratio can be controlled by setting the flow rates of the reaction solution and the cooling medium after the hydrothermal reaction so as to have the above ratio.

The temperature of the cooling medium is not particularly limited, but is preferably higher than the phase transition temperature (about 68 ° C.) of vanadium dioxide, and more preferably 70 to 95 ° C. Instead of the above or in addition to the above, the temperature of the mixture of the reaction solution and water immediately after the hydrothermal reaction is maintained at 70 to 95 ° C. for 5 minutes or longer after the reaction solution after the hydrothermal reaction is mixed with water. More preferably. By setting to such a temperature, the purity of the desired rutile-type crystal phase (R phase) vanadium dioxide can be further improved. In addition, the upper limit of the time for maintaining the temperature of the mixture of the reaction liquid immediately after the hydrothermal reaction and water is not particularly limited, but it is sufficient if it is 10 minutes or less after mixing the reactant immediately after the hydrothermal reaction with water. It is.

When a cooling medium is used, the mixture of the reaction liquid after the hydrothermal reaction and the cooling medium (preferably water) is not particularly limited, but the pH is more preferably 4 to 7. By setting to the said pH, stability of the vanadium dioxide containing particle | grains after particle | grain formation (crystal precipitation) can be improved. Therefore, the purity of vanadium dioxide of the desired rutile type crystal phase (R phase) can be further improved, and the thermochromic properties of the vanadium dioxide-containing particles can be more effectively improved. The means for achieving such a pH value is not particularly limited, and may be achieved by adding the aforementioned pH adjuster to the reaction solution after the hydrothermal reaction before the cooling step. It may be achieved by using a cooling medium mixed with a modifier.

In the case of using a cooling medium, the mixing position of the reaction liquid after the hydrothermal reaction and the cooling medium (installation position of the pipe 11) is not particularly limited, but considering the cooling efficiency of the reaction liquid after the hydrothermal reaction, etc. The pipe 11 is preferably connected to the pipe 3 at a distance of 10 to 500 mm from the outlet of the pipe 3 on the tank 9 side.

In addition, when using the above-mentioned surface modifier or the above-mentioned pH adjuster with a cooling medium, you may provide individually the required equipments, such as the tank 10, the piping 11, and the pump 12, corresponding to each. In the case of using a cooling medium and a surface modifier, or a cooling medium and a pH adjuster, or a mixture of a cooling medium, a pH adjuster and a surface modifier, described in the description of the surface modifier and the pH adjuster. As described above, for a mixture of these, one facility may be used to simultaneously realize a plurality of functions.

The cooled reaction liquid (cooling liquid) after the hydrothermal reaction is replaced with a dispersion medium or a solvent by filtration (for example, ultrafiltration) or centrifugal separation, and the vanadium dioxide-containing particles are replaced with water or alcohol (for example, ethanol). ) Or the like. The obtained vanadium dioxide-containing particles may be dried by any means.

<Vanadium dioxide-containing particles>
Another embodiment of the present invention is vanadium dioxide (VO ₂ ) -containing particles having an average particle diameter (D) of 60 nm or less and a polydispersity index (PDI) of less than 0.30. According to the vanadium dioxide-containing particles according to the present embodiment, means for improving the thermochromic properties of the vanadium dioxide-containing particles and the transparency of the optical film containing the vanadium dioxide-containing particles (reducing haze) is provided. The manufacturing method according to an aspect of the present invention provides vanadium dioxide-containing particles having excellent thermochromic properties of vanadium dioxide (VO ₂ ) -containing particles and transparency of an optical film including vanadium dioxide-containing particles. Is preferably manufactured by the manufacturing method according to one aspect of the present invention.

The vanadium dioxide-containing particles according to an embodiment of the present invention have a small particle size and a narrow particle size distribution. Here, the average particle diameter (D) of the vanadium dioxide-containing particles is not particularly limited, but is preferably 60 nm or less, more preferably 40 nm or less, further preferably 35 nm or less, and 25 nm or less. More preferably, it is particularly preferably 15 nm or less, particularly preferably 10 nm or less, and most preferably 8 nm or less. The lower limit of the average particle diameter (D) (nm) of the vanadium dioxide-containing particles is not particularly limited, but is preferably 2 nm or more. With vanadium dioxide-containing particles having such a particle size, haze can be lowered more favorably and thermochromic properties can be further improved. The particle diameter of the vanadium dioxide-containing particles can be measured by an electron microscope observation or a particle diameter measurement method based on a dynamic light scattering method. When measuring the particle diameter based on the dynamic light scattering method, the fluid is analyzed by the dynamic light scattering (Dynamic Light Scattering, DLS) method using a dynamic light scattering analyzer (DLS-8000, manufactured by Otsuka Electronics Co., Ltd.). Measure the mechanical diameter. In this specification, the value measured by the method described in the below-mentioned Example is employ | adopted for the average particle diameter (D) (nm) of vanadium dioxide containing particle | grains.

Further, the particle size distribution of the vanadium dioxide-containing particles is not particularly limited, but when the polydispersity index (PDI) is used as an index, the polydispersity index (PDI) is preferably less than 0.30. It is more preferably from 01 to 0.25, further preferably from 0.01 to 0.15, particularly preferably from 0.01 to 0.10, and preferably from 0.01 to 0.08. Is most preferred. The vanadium dioxide-containing particles having a particle size distribution exhibiting such a polydispersity index (PDI) can effectively improve the thermochromic properties of the vanadium dioxide-containing particles and the transparency of the optical film containing the vanadium dioxide-containing particles. In this specification, “polydispersity index (PDI)” indicating the particle size distribution of vanadium dioxide-containing particles adopts a value measured by a method described in Examples described later.

The vanadium dioxide-containing particles obtained by the production method according to an aspect of the present invention, or the vanadium dioxide-containing particles according to an aspect of the present invention, for example, mixed with a resin such as polyvinyl alcohol and used for a heat shielding film, It can be used for thermochromic pigments.

<Dispersion and method for producing dispersion>
Another embodiment of the present invention includes a step of producing vanadium dioxide-containing particles by the production method according to one embodiment of the present invention, and a step of dispersing the vanadium dioxide-containing particles in a dispersion medium. It is a manufacturing method of a liquid. Yet another embodiment of the present invention is a dispersion containing vanadium dioxide-containing particles according to an embodiment of the present invention.

Since the vanadium dioxide-containing particles according to the present invention have a small particle size and a narrow particle size distribution (uniform particle size), by applying a dispersion containing such particles, the thermochromic properties are improved, The effect of haze can be reduced. For this reason, a highly transparent film of an optical film containing vanadium dioxide-containing particles can be provided.

As the dispersion, the reaction liquid after the hydrothermal reaction step or the cooling liquid (reaction liquid) after the cooling process is used as it is, or the reaction liquid or cooling liquid (reaction liquid) after the hydrothermal reaction step is used as water or alcohol. Etc. may be added for dilution, or the dispersion medium of the reaction liquid or cooling liquid (reaction liquid) after the hydrothermal reaction step may be replaced with water or alcohol.

The method for dispersing the vanadium dioxide-containing particles is not particularly limited, and for example, ultrasonic waves may be used.

The dispersion medium of the dispersion may be composed only of water. For example, in addition to water, an organic solvent of about 0.1 to 10% by mass (in the dispersion), for example, methanol, ethanol, isopropanol, butanol And alcohols such as acetone, ketones such as acetone, and the like. Moreover, as a dispersion medium, a phosphate buffer, a phthalate buffer, etc. can also be used.

The dispersion may contain an organic or inorganic acid or alkali such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, phthalic acid, ammonium hydroxide, ammonia, etc., and may be adjusted to a desired pH.

From the viewpoint of suppressing aggregation of vanadium dioxide-containing particles in the dispersion, the pH of the dispersion is preferably 4-7.

From the viewpoint of dispersion stability, the concentration of the vanadium dioxide-containing particles in the dispersion is preferably 0.01 to 40% by mass, and 0.5 to 40% by mass with respect to the total mass of the dispersion. More preferably, it is 1 to 30% by mass.

<Optical film and method for producing optical film>
By using the vanadium dioxide particles according to one embodiment of the present invention, an optical film having an optical functional layer containing the vanadium dioxide particles and a resin can be manufactured. As a method for producing such an optical film, a process for producing vanadium dioxide-containing particles by a production method according to one embodiment of the present invention, and forming a resin composition containing the vanadium dioxide-containing particles and a resin are formed. It is preferable that it is a manufacturing method of the optical film which has the process of forming an optical function layer by this. According to another aspect of the present invention, after preparing a coating liquid containing a step of producing vanadium dioxide-containing particles by a production method according to one aspect of the present invention, a resin, vanadium dioxide-containing particles, and a dispersion medium. And a step of forming an optical functional layer by applying a coating liquid on a transparent substrate and drying it, and a method for producing an optical film comprising a transparent substrate and an optical functional layer. Another embodiment of the present invention includes a transparent substrate and an optical functional layer formed on the transparent substrate, and the optical functional layer contains the vanadium dioxide-containing particles according to one embodiment of the present invention. It is an optical film.

(Transparent substrate)
Here, the transparent substrate applicable to the optical film is not particularly limited as long as it is transparent, and examples thereof include glass, quartz, and a transparent resin film. From the viewpoint of suitability, it is preferably a transparent substrate. 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 according to one embodiment of 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. is there. 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 Follow-up performance is further improved.

The transparent substrate according to an embodiment of 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 optical film and cracking of the infrared reflective layer. Preferably, the content is in the range of 1.5 to 3.0%, more preferably 1.9 to 2.7%.

As described above, the transparent substrate applicable to the optical film according to an embodiment of the present invention is not particularly limited as long as it is transparent, but various transparent resin films are preferably used. A film (for example, polyethylene, polypropylene, etc.), a polyester film (for example, polyethylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride, a triacetyl cellulose film, etc. can be used, preferably a polyester film or a triacetyl cellulose film. More preferably, it is a polyester film.

The polyester film (hereinafter simply referred to as “polyester”) is not particularly limited, but is preferably a polyester having a film-forming property having a dicarboxylic acid component and a diol component as main components. The main constituent dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylethanedicarboxylic acid, Examples thereof include cyclohexane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl thioether dicarboxylic acid, diphenyl ketone dicarboxylic acid, and phenylindane dicarboxylic acid. Examples of the diol component include ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyethoxyphenyl) propane, bis ( 4-Hydroxyphenyl) sulfone, bisphenol fluorene hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like. Among the polyesters having these as main components, from the viewpoints of transparency, mechanical strength, dimensional stability, etc., dicarboxylic acid components such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, diol components such as ethylene glycol and 1 Polyester having 1,4-cyclohexanedimethanol as the main constituent is preferred. Among them, polyethylene terephthalate, polyethylene naphthalate, polyesters containing these as main constituents, copolymer polyesters composed of terephthalic acid, 2,6-naphthalenedicarboxylic acid and ethylene glycol, and two or more of these polyesters A polyester having a mixture as a main constituent is preferred.

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

In the case of using a transparent resin film as a transparent substrate according to an embodiment of the present invention, particles may be contained within a range that does not impair transparency in order to facilitate handling. Examples of particles that can be used for the transparent resin film include inorganic particles such as calcium carbonate, calcium phosphate, silica, kaolin, talc, titanium dioxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide. And organic particles such as crosslinked polymer particles and calcium oxalate. Examples of the method of adding particles include a method of adding particles in a raw material resin (for example, polyester), a method of adding particles directly to an extruder, and the like. May be employed, or two methods may be used in combination. In the present invention, additives may be added in addition to the above particles as necessary. Examples of such additives include stabilizers, lubricants, crosslinking agents, antiblocking agents, antioxidants, dyes, pigments, ultraviolet absorbers and the like.

A transparent resin film that is a transparent substrate can be produced by a conventionally known general method. For example, a dope is prepared by mixing a resin as a material with a solvent, and the dope is cast on a continuous support to form a film, and after partially drying on the continuous support, from the continuous support An unstretched or stretched transparent resin film can be produced by peeling and then sufficiently drying and optionally performing a stretching treatment during and / or after drying. Further, for example, an unstretched transparent resin film that is substantially amorphous and not oriented can be produced by melting a resin as a material with an extruder, extruding it with an annular die or a T-die, and quenching. . The unstretched transparent resin film is uniaxially stretched, tenter-type sequential biaxial stretching, tenter-type simultaneous biaxial stretching, tubular simultaneous biaxial stretching, and other known methods such as transparent resin film flow (vertical axis) direction. Alternatively, a stretched transparent resin film can be produced by stretching in the direction perpendicular to the flow direction of the transparent resin film (horizontal axis). The draw ratio in this case can be appropriately selected according to the resin used as the raw material of the transparent resin film, but is preferably 2 to 10 times in the vertical axis direction and the horizontal axis direction. Moreover, you may further perform the said extending | stretching process with respect to the transparent resin film previously extended | stretched.

Further, the transparent resin film may be subjected to relaxation treatment or offline heat treatment in terms of dimensional stability. It is preferable that the relaxation treatment is performed in a process from the heat setting in the stretching process of the polyester film to the winding in the transversely stretched tenter or after exiting the tenter. The relaxation treatment is preferably performed at a treatment temperature of 80 to 200 ° C., more preferably a treatment temperature of 100 to 180 ° C. In addition, the relaxation rate is preferably in the range of 0.1 to 10% in both the longitudinal direction and the width direction, and more preferably, the relaxation rate is 2 to 6%. The relaxed substrate is subjected to off-line heat treatment to improve heat resistance and to improve dimensional stability.

The transparent resin film is preferably coated with the undercoat layer coating solution in-line on one or both sides during the film forming process. In the present invention, undercoating during the film forming process is referred to as in-line undercoating. Examples of the resin used for the undercoat layer coating solution useful for the transparent resin film according to one embodiment of the present invention include polyester resin, (meth) acryl-modified polyester resin, polyurethane resin, acrylic resin, vinyl resin, and vinylidene chloride resin. , Polyethyleneimine vinylidene resin, polyethyleneimine resin, polyvinyl alcohol resin, modified polyvinyl alcohol resin, gelatin and the like, and any of them can be preferably used. A conventionally well-known additive can also be added to these undercoat layers. The undercoat layer can be coated by a known method such as roll coating, gravure coating, knife coating, dip coating or spray coating. The coating amount of the undercoat layer is preferably about 0.01 to 2 g / m ² (dry state).

(Optical function layer)
The optical film which concerns on one form of this invention has an optical function layer containing resin and the vanadium dioxide containing particle | grains which concern on this invention. The optical film preferably has a structure having an optical functional layer containing a resin and vanadium dioxide-containing particles according to the present invention on the transparent substrate and the transparent substrate.

Here, the resin is not particularly limited, and the same resin as that conventionally used for the optical functional layer can be used. Preferably, a water-soluble polymer can be used. Here, the water-soluble polymer 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, a 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, polyvinyl pyrrolidone (PVP), polyvinyl methyl ether, carboxyvinyl polymer, poly (meth) acrylic acid, poly (meth) Sodium acrylate, naphthalene sulfonic acid condensate, proteins such as albumin and casein, sodium alginate, dextrin, dextran, dextran sulfate, etc. Mention may be made of a sugar derivatives and the like.

The content of the vanadium dioxide-containing particles in the optical functional layer is preferably 1 to 60% by mass with respect to the total mass of the optical functional layer from the viewpoint of obtaining a desired thermochromic property. It is more preferable that

In the optical functional layer, additives can be used as long as the effects of the present invention 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, JP-A-57- No. 878989, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091, JP-A-3-13376, etc. 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 PH adjustment of fluorescent brighteners, sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, etc. described in No. 219266 , Antifoaming agents, lubricants such as diethylene glycol, preservatives, antifungal agents, antistatic agents, matting agents, heat stabilizers, antioxidants, flame retardants, crystal nucleating agents, inorganic particles, organic particles, viscosity reducers, Examples include various known additives such as lubricants, infrared absorbers, dyes, and pigments.

The method for forming the optical functional layer is not particularly limited, and can be applied in the same manner or appropriately modified except that the vanadium dioxide-containing particles according to one embodiment 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.

The coating solution preferably contains a resin and vanadium dioxide-containing particles. In addition, the coating liquid may be prepared by appropriately adding a resin or a solvent using the reaction liquid after the hydrothermal reaction obtained by the production method according to one aspect of the present invention or the dispersion liquid according to one aspect of the present invention. It may be prepared. In addition, the coating liquid is prepared by adding the vanadium dioxide-containing particles obtained by the manufacturing method according to one embodiment of the present invention, the vanadium dioxide-containing particles according to one embodiment of the present invention, and a resin to the dispersion medium. May be. As the dispersion medium contained in the coating liquid, the same dispersion medium as described in the dispersion liquid and the method for producing the dispersion liquid can be used. The total mass of the resin and vanadium dioxide-containing particles with respect to the total mass of the coating solution is not particularly limited as long as the optical functional layer can be formed by a wet coating method, and is appropriately set according to the required film thickness and film formation conditions. can do.

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 curtain coating method, or US Pat. No. 2,761,419. Examples thereof include a slide hopper coating method and an extrusion coating method described in the specification and US Pat. No. 2,761,791.

(Other layers)
The optical film according to one embodiment of the present invention may further include other layers in addition to the above-described constituent members. Here, the other layers are not particularly limited as long as the effects of the present invention are not hindered. For example, the near-infrared shielding layer, the ultraviolet absorption layer, the gas barrier layer, the corrosion prevention layer, the anchor layer (primer layer), and the adhesive layer. And a hard coat layer.

The effect of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples. In the following examples, the operation was performed at room temperature (25 ° C.) unless otherwise specified. Unless otherwise specified, “%” and “part” mean “% by mass” and “part by mass”, respectively.

<Production of vanadium dioxide-containing particles>
(Comparative Example 1)
Dissolve 1 g of vanadium oxide (IV) sulfate (VOSO ₄ ) in ion-exchanged water to 10 mL, 1 mol / L sodium hydroxide (NaOH, diluted by ion-exchanged water, manufactured by Wako Pure Chemical Industries, Ltd.) with stirring Was added until pH 7.0. This suspension (reaction solution) was put into a 50 mL autoclave and subjected to a hydrothermal reaction treatment at 250 ° C. and 3.98 MPa for 8 hours to form vanadium dioxide (VO ₂ ) -containing particles. Then, after cooling, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Comparative Example 2)
A suspension prepared in the same manner as in Comparative Example 1 was placed in a 50 mL autoclave and subjected to a hydrothermal reaction treatment at 270 ° C. and 5.51 MPa for 24 hours to form vanadium dioxide (VO ₂ ) -containing particles. Then, after cooling, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Example 1)
The suspension prepared in the same manner as in Comparative Example 1 was placed in an autoclave capable of being pressurized with compressed nitrogen, pressurized to 10.00 MPa, and hydrothermal reaction treatment was performed at 270 ° C. for 24 hours under this pressure. , Vanadium dioxide (VO ₂ ) -containing particles were formed. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a subcritical state. Then, after cooling, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Example 2)
A solution (raw material solution 1) in which 0.5 g of vanadium oxide (IV) (VOSO ₄ ) is dissolved in ion-exchanged water to 10 mL and a 1 mol / L sodium hydroxide aqueous solution (NaOH, manufactured by Wako Pure Chemical Industries, Ltd.) A solution (raw material liquid 2) that is diluted with ion-exchanged water is put in the raw material liquid container 2 and the raw material liquid container 5 of the microreactor type flow reactor shown in FIG. Immediately after mixing to prepare a reaction solution, hydrothermal reaction treatment was performed at 270 ° C. and 10.00 MPa for 2.0 seconds in the microreactor unit 16 to form vanadium dioxide (VO ₂ ) -containing particles. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a subcritical state. Then, after cooling in the cooling pipe 8, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Example 3)
A hydrothermal reaction treatment was performed in the same manner as in Example 2 except that 1 mol / L ammonia water (ammonia was diluted with ion-exchanged water) was used instead of the 1 mol / L sodium hydroxide aqueous solution, and vanadium dioxide ( VO ₂ ) containing particles were formed. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a subcritical state. Then, after cooling in the cooling pipe 8, a dispersion containing vanadium dioxide-containing particles and water was recovered.

Example 4
Example 2 of the raw material solution further ammonium tungstate para pentahydrate in _{_{_{_{1 ((NH 4) 10 W}}}} 12 O 41 · 5H 2 O, manufactured by Wako Pure Chemical Industries, Ltd.) vanadium: atomic ratio of tungsten 99: A hydrothermal reaction treatment was performed in the same manner as in Example 2 except that the particles were dissolved so that vanadium dioxide (VO ₂ ) -containing particles were formed. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a subcritical state. Then, after cooling in the cooling pipe 8, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Example 5)
A hydrothermal reaction treatment was carried out in the same manner as in Example 2 except that nitrogen (N ₂ ) nanobubble-treated water (liquid temperature = 25 ° C.) was used instead of ion-exchanged water, and vanadium dioxide (VO ₂ ). Containing particles were formed. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a subcritical state. Then, after cooling in the cooling pipe 8, a dispersion containing vanadium dioxide-containing particles and water was recovered. In addition, the nitrogen (N ₂ ) nanobubble-treated water is a high density ultrafine bubble generator (Nanokus Co., Ltd., Nanoquick (registered trademark)), and nitrogen gas is ion-exchanged in a sealed system. Prepared by mixing, the dissolved oxygen concentration was about 0.6 mg / L.

(Example 6)
In the microreactor section 16, hydrothermal reaction treatment was performed in the same manner as in Example 5 except that hydrothermal reaction treatment was performed at 400 ° C. and 30.00 MPa for 2.0 seconds to form vanadium dioxide (VO ₂ ) -containing particles. did. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a supercritical state. Then, after cooling in the cooling pipe 8, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Example 7)
Ammonia water (concentration 28% by mass, Wako Pure Chemical Industries, Ltd., special grade) is added to a mixed solution of ethanol (Wako Pure Chemical Industries, Ltd., first grade) 20 mL and pure water 5 mL, and the pH value is 11. 8 solutions were prepared. To this solution, 0.3 g of tetraethyl orthosilicate ((C ₂ H ₅ O) ₄ Si, manufactured by Wako Pure Chemical Industries, Ltd., special grade) was added and stirred and mixed at 80 ° C. for 4 hours to obtain a surface modifier. A solution was prepared. This surface modifier solution was charged into the tank 10 of the microreactor type flow reactor shown in FIG. As in Example 6, immediately after the raw material liquid 1 and the raw material liquid 2 were mixed and subjected to a hydrothermal reaction (within 5 seconds), the surface modifier solution was transferred from the surface modification tank 10 through the pipe 11. The tetraethyl orthosilicate was mixed in an amount of 2% by mass with respect to the mass of the generated vanadium dioxide (VO ₂ ) -containing particles. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a supercritical state. Then, after cooling in the cooling pipe 8, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Comparative Example 3)
0.5 g of ammonium vanadate (NH ₄ VO ₃ , manufactured by Wako Pure Chemical Industries, Ltd., special grade) was dissolved in ion-exchanged water at 60 ° C. to make 10 mL, and hydrazine hydrate (N ₂ H ₄ .H ₂ O, An aqueous solution obtained by diluting Wako Pure Chemical Industries, Ltd. (special grade) to 5% by mass with ion exchange water was slowly added dropwise to adjust the pH to 9.5. This solution (reaction solution) was placed in a 50 mL autoclave and subjected to a hydrothermal reaction treatment at 250 ° C. and 3.98 MPa for 24 hours to form vanadium dioxide (VO ₂ ) -containing particles. Then, after cooling, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Comparative Example 4)
A solution prepared in the same manner as in Comparative Example 3 was placed in a 50 mL autoclave and subjected to a hydrothermal reaction treatment at 270 ° C. and 5.51 MPa for 24 hours to form vanadium dioxide (VO ₂ ) -containing particles. Then, after cooling, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Example 8)
The solution prepared in the same manner as in Comparative Example 3 was put in an autoclave that can be pressurized with compressed nitrogen, pressurized to 10.00 MPa, and subjected to a hydrothermal reaction treatment at 270 ° C. for 24 hours under this pressure. Vanadium (VO ₂ ) containing particles were formed. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a subcritical state. Then, after cooling, a dispersion containing vanadium dioxide-containing particles and water was recovered.

Example 9
A solution (raw material liquid 1) and hydrazine hydrate (N ₂ ) containing 0.5 g of ammonium vanadate (NH ₄ VO ₃ , Wako Pure Chemical Industries, Ltd., special grade) dissolved in ion-exchanged water at 60 ° C. to make 10 mL. A solution obtained by diluting H ₄ · H ₂ O (manufactured by Wako Pure Chemical Industries, Ltd., special grade) to 5% by mass with ion-exchanged water (raw material liquid 2) is a raw material of the microreactor type flow reactor shown in FIG. Immediately after being put in the liquid container 2 and the raw material liquid container 5 and mixed at a mixing ratio of pH 9.5 to obtain a reaction liquid, in the microreactor unit 16 270 ° C., 10.00 MPa, water for 2.0 seconds. Thermal reaction treatment was performed to form particles containing vanadium dioxide (VO ₂ ). Here, the water in the reaction solution during the hydrothermal reaction treatment is in a subcritical state. Then, after cooling in the cooling pipe 8, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Example 10)
Further ammonium tungstate para pentahydrate in raw material liquid 1 of Example _{_{_{_{9 ((NH 4) 10 W}}}} 12 O 41 · 5H 2 O, manufactured by Wako Pure Chemical Industries, Ltd.) vanadium: atomic ratio of tungsten 99: A hydrothermal reaction treatment was performed in the same manner as in Example 9 except that the particles were dissolved so as to be 1, and vanadium dioxide (VO ₂ ) -containing particles were formed. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a subcritical state. Then, after cooling in the cooling pipe 8, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Example 11)
A hydrothermal reaction treatment was performed in the same manner as in Example 9 except that water (liquid temperature = 25 ° C) treated with nitrogen (N ₂ ) nanobubbles was used instead of ion-exchanged water, and vanadium dioxide (VO ₂ ). Containing particles were formed. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a subcritical state. Then, after cooling in the cooling pipe 8, a dispersion containing vanadium dioxide-containing particles and water was recovered. In addition, the nitrogen (N ₂ ) nanobubble-treated water is a high density ultrafine bubble generator (Nanokus Co., Ltd., Nanoquick (registered trademark)), and nitrogen gas is ion-exchanged in a sealed system. Prepared by mixing, the dissolved oxygen concentration was about 0.6 mg / L.

Example 12
In the microreactor section 16, hydrothermal reaction treatment was performed in the same manner as in Example 11 except that hydrothermal reaction treatment was performed at 400 ° C. and 30.00 MPa for 2.0 seconds to form vanadium dioxide (VO ₂ ) -containing particles. did. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a supercritical state. Then, after cooling in the cooling pipe 8, a dispersion containing vanadium dioxide-containing particles and water was recovered.

(Example 13)
Ammonia water (concentration 28% by mass, Wako Pure Chemical Industries, Ltd., special grade) is added to a mixed solution of ethanol (Wako Pure Chemical Industries, Ltd., first grade) 20 mL and pure water 5 mL, and the pH value is 11. 8 solutions were prepared. To this solution, 0.3 g of tetraethyl orthosilicate ((C ₂ H ₅ O) ₄ Si, manufactured by Wako Pure Chemical Industries, Ltd., special grade) was added and stirred and mixed at 80 ° C. for 4 hours to obtain a surface modifier. A solution was prepared. This surface modifier solution was charged into the tank 10 of the microreactor type flow reactor shown in FIG. In the same manner as in Example 12, immediately after the raw material liquid 1 and the raw material liquid 2 were mixed and subjected to the hydrothermal reaction (within 5 seconds), the surface modifier solution was transferred from the surface modification tank 10 through the pipe 11. The tetraethyl orthosilicate was mixed in an amount of 2% by mass with respect to the mass of the generated vanadium dioxide (VO ₂ ) -containing particles. Here, the water in the reaction solution during the hydrothermal reaction treatment is in a supercritical state. Then, after cooling in the cooling pipe 8, a dispersion containing vanadium dioxide-containing particles and water was recovered.

The conditions of Examples 1 to 13 and Comparative Examples 1 to 4 are shown in Tables 1 and 2 below.

<Performance evaluation>
For the vanadium dioxide-containing particles obtained in Examples 1 to 13 and Comparative Examples 1 to 4, the average particle diameter (D) and polydispersity index (PDI) were measured according to the following methods.

Further, the haze and thermochromic properties of the vanadium dioxide-containing particles obtained in Examples 1 to 13 and Comparative Examples 1 to 4 were evaluated according to the following methods.

(Average particle diameter (D))
Each vanadium dioxide-containing particle and water-containing dispersion obtained in each example and each comparative example was adjusted so that the concentration of vanadium dioxide-containing particles was 0.01% by mass with respect to the total mass of the dispersion. The sample for measurement was prepared by mixing with water and dispersing with ultrasonic waves for 15 minutes. A hydrodynamic diameter (nm) was measured by a dynamic light scattering (DLS) method using a dynamic light scattering analyzer (DLS-8000, manufactured by Otsuka Electronics Co., Ltd.). And based on this, the average particle diameter of the particle diameter distribution by cumulant analysis was calculated | required, and this value was made into the average particle diameter (D) (nm).

(Polydispersity index (PDI))
The polydispersity index (PDI) is a numerical value calculated on the assumption that the particle size distribution is a normal distribution in the cumulant analysis measured by the dynamic light scattering method (DLS method) in the same manner as the measurement of the average particle size (D). did.

(Thermochromic properties)
Each vanadium dioxide-containing particle dispersion obtained in each example and each comparative example was subjected to a flow rate of 300 ml / min and a hydraulic pressure of 1 bar using Vivaflow 50 (effective filtration area 50 cm ² , molecular weight cut-off 5000) manufactured by Sartorius steady. The concentration was adjusted by filtration at (0.1 MPa), and polyvinyl alcohol was mixed so that the vanadium dioxide-containing particles were 10% by mass with respect to the total mass of the polyvinyl alcohol and vanadium dioxide-containing particles. A film for measurement (optical film) having an optical functional layer with a dry film thickness of 3 μm was prepared by applying and drying on a 50 μm thick polyethylene terephthalate (PET) substrate manufactured by DuPont Films.

Each measurement film was stored at 25 ° C./50% RH for 24 hours to evaluate thermochromic properties.

Specifically, each transmittance at a wavelength of 2000 nm at 25 ° C./50% RH and 85 ° C./50% RH was measured, and the calculated transmittance difference (ΔT) (%) was evaluated according to the following evaluation criteria. . The measurement was performed by attaching a temperature control unit (manufactured by JASCO Corporation) to a spectrophotometer V-670 (manufactured by JASCO Corporation). Here, the larger the transmittance difference (ΔT) is, the better, and if it is “Δ” or more in the following evaluation, it is acceptable;
A: Transmittance difference is 40% or more. O: Transmittance difference is 30% or more and less than 40%. Δ: Transmittance difference is 20% or more and less than 30%. X: Transmittance difference is less than 20%. .

(Transparency (haze evaluation)))
The transparency of the optical film was evaluated by the haze value. About each film for a measurement produced similarly to the measurement of the said thermochromic property ((DELTA) T) (%), haze (%) was measured using the haze meter (Nippon Denshoku Industries Co., Ltd. make, NDH5000) at room temperature. . Moreover, the haze value calculated above was evaluated according to the following criteria. Here, the smaller the haze (%), the better. In the following evaluation, “Δ” or more is acceptable;
◎: Less than 1.0% ○: 1.0% or more and less than 1.5% ○ △: 1.5% or more and less than 2.0% △: 2.0% or more and less than 2.5% X: 2.5% or more.

These evaluation results are shown in Table 3 below.

From the results of Table 3 above, it was confirmed that the vanadium dioxide (VO ₂ ) -containing particles of the examples according to the present invention were excellent in thermochromic properties and low in haze as compared with those of the comparative examples. The above results are considered to be because the average particle diameter (D) of the vanadium dioxide-containing particles of the examples is small, and the polydispersity index (PDI) is small and the particle diameter (D) is uniform.

Moreover, among the vanadium dioxide (VO ₂ ) -containing particles of the examples, it was confirmed that the examples produced using a microreactor type flow reactor were particularly excellent in thermochromic properties and low in haze.

This application is based on Japanese Patent Application No. 2015-138167 filed on July 9, 2015, the disclosure of which is incorporated by reference in its entirety.

Claims

A reaction liquid obtained by mixing a raw material liquid containing a vanadium-containing compound and water and a raw material liquid containing a compound that reacts with the vanadium-containing compound and water is treated with water in the presence of subcritical or supercritical water. having thereby thermal reaction method of vanadium dioxide (VO 2) containing particles.
The production method according to claim 1, wherein the vanadium dioxide-containing particles have an average particle size (D) of 60 nm or less and a polydispersity index (PDI) of less than 0.30.
The production method according to claim 1 or 2, wherein the vanadium-containing compound is a vanadium (IV) -containing compound, and the compound that reacts with the vanadium-containing compound contains at least one alkali.
The production method according to claim 1 or 2, wherein the vanadium-containing compound is a vanadium (V) -containing compound, and the compound that reacts with the vanadium-containing compound includes at least one of hydrazine and a hydrate thereof.
The production method according to any one of claims 1 to 4, wherein the hydrothermal reaction is performed using a microreactor type flow reactor.
The production method according to any one of claims 1 to 5, wherein the raw material liquid containing the vanadium-containing compound and water further contains a substance containing an element for adjusting the phase transition temperature of the vanadium dioxide-containing particles.
The production method according to any one of claims 1 to 6, wherein the water in the reaction solution is water treated with nitrogen (N 2 ) nanobubbles.
The production method according to any one of claims 1 to 7, wherein a surface modifier is further added immediately after the hydrothermal reaction.
A step of producing vanadium dioxide-containing particles by the production method according to any one of claims 1 to 8,
Dispersing the vanadium dioxide-containing particles in a dispersion medium;
A method for producing a dispersion liquid.
A step of producing vanadium dioxide-containing particles by the production method according to any one of claims 1 to 8,
After preparing a coating liquid containing a resin, the vanadium dioxide-containing particles, and a dispersion medium, a step of forming the optical functional layer by applying the coating liquid on a transparent substrate and drying;
including,
The manufacturing method of an optical film containing a transparent base material and an optical function layer.
Vanadium dioxide (VO 2 ) -containing particles having an average particle diameter (D) of 60 nm or less and a polydispersity index (PDI) of less than 0.30.
A dispersion containing the vanadium dioxide-containing particles according to claim 11.
A transparent substrate, and an optical functional layer;
An optical film in which the optical functional layer contains the vanadium dioxide-containing particles according to claim 11.