WO2020044981A1

WO2020044981A1 - Method for producing vanadium dioxide-containing particles

Info

Publication number: WO2020044981A1
Application number: PCT/JP2019/030815
Authority: WO
Inventors: 山本　昌一
Original assignee: コニカミノルタ株式会社
Priority date: 2018-08-31
Filing date: 2019-08-06
Publication date: 2020-03-05
Also published as: JP7173150B2; JPWO2020044981A1

Abstract

The present invention addresses the problem of providing a method for producing vanadium dioxide-containing particles, by which it is possible to produce vanadium dioxide-containing particles having a small average particle diameter and obtain an optical film having low haze and excellent thermochromic properties by using the vanadium dioxide-containing particles.　This method for producing vanadium dioxide-containing particles is a method in which vanadium dioxide-containing particles are produced by means of a hydrothermal synthesis method using a circulating reactor and using a reaction liquid obtained by mixing supercritical water or subcritical water with a raw material slurry containing a vanadium-containing compound and a compound that reacts with the vanadium-containing compound. The production method is characterized in that vanadium dioxide-containing particles having a pH of 8.0-11.0, an electrical conductivity within the range 10-1000 mS/m, an average primary particle diameter of 1-30 nm and an average crystallite diameter within the range 1-15 nm are produced by subjecting the raw material slurry to a desalting treatment prior to the hydrothermal synthesis method.

Description

Method for producing vanadium dioxide-containing particles

The present invention relates to a method for producing vanadium dioxide-containing particles having a small average particle diameter by a hydrothermal synthesis method using a flow-type reactor.

In a building such as a house or a building, and a moving body such as a vehicle, a place where a large heat exchange occurs between an internal environment such as a room or a vehicle and an external environment, for example, a window glass for a building or a window glass for a vehicle body. In order to achieve both energy saving and comfortableness, application of thermochromic materials has been actively studied.

The term "thermochromic material" as used herein refers to, for example, a material that enables optical characteristics typified by light transmittance to be controlled by temperature.For example, a thermochromic material is applied to a window glass of a building. In this case, it is a material that can reflect heat in the room by reflecting infrared rays in summer and transmit infrared rays in the room in winter in order to use the heat energy.

In recent years, one of the thermochromic materials that has received the most attention is a material containing vanadium dioxide (VO ₂ ). It is known that vanadium dioxide exhibits "thermochromic property", which is a property that optical properties reversibly change with temperature when a phase transition occurs near room temperature. Therefore, by utilizing this property, it is possible to obtain a material exhibiting an environmental temperature-dependent thermochromic property.

Here, vanadium dioxide has several crystal phases such as an A phase, a B phase, a C phase, and a rutile type crystal phase (hereinafter, also referred to as an “R phase”). The crystal structure exhibiting chromic properties at a relatively low temperature of 100 ° C. or lower is limited to the R phase (rutile type crystal phase). The R phase has a monoclinic structure at a temperature lower than the phase transition temperature (about 68 ° C.), and exhibits high transmittance of visible light and infrared light. On the other hand, the R phase has a tetragonal structure in a temperature range of 68 ° C. or higher, which is a phase transition temperature, and exhibits a property of lower infrared transmittance than a monoclinic structure. That is, it has a unique property that the transmittance of infrared rays greatly changes around the phase transition temperature.

When vanadium dioxide-containing particles having such properties are applied to an optical film used by being attached to a window glass or the like, transparency (low haze) as the particles is required. It is desirable that the vanadium-containing particles are not agglomerated (the secondary particle size is small) and that the particle size is in the nano order (100 nm or less).

As a method for producing vanadium dioxide-containing particles which are fine particles having high transparency, a method of producing R-phase vanadium dioxide particles using a hydrothermal reaction has recently been reported.

For example, Patent Document 1 discloses that the composition and composition of a doped vanadium dioxide powder (V _1−x M _x O ₂ ) are adjusted so that the doping element satisfies 0 <x ≦ 0.5. Is disclosed as being controllable. Further, as a result, it is disclosed that the size of the crystallite diameter of the manufactured doped vanadium dioxide powder can be reduced and made uniform. Then, as a method for producing doped vanadium dioxide powder, the reaction precursor treated so that the hydrothermal reaction can be performed more easily is transferred to a hydrothermal reaction autoclave, and the hydrothermal reaction is performed. A method for drying and separating is disclosed.

However, the method disclosed in Patent Literature 1 is a batch-type production apparatus using a hydrothermal autoclave, and requires a long hydrothermal reaction time of 6 to 12 hours. Since the average particle diameter is large and the distribution is wide, when the vanadium dioxide-containing particles are applied to an optical film, the film has a high haze and is not suitable as a film for use in vehicles or building materials.

文献 Patent Document 2 discloses a hydrothermal synthesis method using high-temperature, high-pressure water in a supercritical state as a production method using a flow-type reactor. In the hydrothermal synthesis method using a flow-type reaction apparatus disclosed in Patent Document 2, when synthesizing fine particles, functional alkaline particles are supplied by supplying an alkaline aqueous solution to a reaction field and adjusting the pH. It is a method of controlling the diameter, but since the particles are formed in the same environment without removing the salts and the like which are excessively present in the particle formation process, the crystallite diameter and the particle diameter of the particles are adjusted to the desired conditions. However, there is a problem that the particle size distribution is widened, which causes a decrease in thermochromic property and a decrease in transparency (haze) when applied to an optical film.

JP 2014-505651 A JP 2010-069474 A

The present invention has been made in view of the above-described problems and circumstances, and a problem to be solved is to provide a vanadium dioxide-containing particle capable of obtaining an optical film having a small average particle size, a low haze, and excellent thermochromic properties. It is to provide a manufacturing method.

The present inventor has studied the causes of the above problems in order to solve the above problems, and found that in a method for producing vanadium dioxide-containing particles using a flow-type reaction apparatus having a hydrothermal reaction section, a vanadium-containing compound, Particles containing vanadium dioxide having an average primary particle size of 1 to 30 nm and an average crystallite size of 1 to 15 nm by adjusting the conditions of the step of desalting the slurry raw material liquid containing the agent and water. The present inventors have found a method for producing vanadium dioxide-containing particles capable of obtaining an optical film having a small average particle size, a low haze, and an excellent thermochromic property by the method for producing the present invention, and have led to the present invention.

That is, the above-mentioned subject according to the present invention is solved by the following means.

1. A method for producing vanadium dioxide-containing particles using a flow reactor having a hydrothermal reaction section,
It has at least the following first to third steps:
First step: a step of preparing a slurry raw material liquid containing at least a vanadium-containing compound, a reaction modifier, and water Second step: a step of subjecting the slurry raw material liquid to a desalting treatment Third step: applying the desalting treatment A step of producing vanadium dioxide-containing particles by a hydrothermal reaction method using a reaction liquid obtained by mixing a slurry raw material liquid and water in a supercritical or subcritical state. In the second step, the pH of the slurry raw material liquid at 25 ° C. Within the range of 8.0 to 11.0,
Maintaining the electrical conductivity at 25 ° C. within the range of 10 to 1000 mS / m;
The average primary particle diameter of the vanadium dioxide-containing particles is in the range of 1 to 30 nm, and
A method for producing vanadium dioxide-containing particles, wherein the particles are produced by adjusting the average crystallite diameter to fall within a range of 1 to 15 nm.

{2. 2. The method for producing vanadium dioxide-containing particles according to claim 1, wherein the desalting treatment for removing salts from the slurry raw material liquid is performed using an ultrafiltration device.

{3. The method for producing vanadium dioxide-containing particles according to claim 1 or 2, wherein the desalting treatment for removing salts from the slurry raw material liquid is performed at a liquid temperature of 30 ° C or lower.

4. The method for producing vanadium dioxide-containing particles according to any one of claims 1 to 3, wherein water constituting the reaction solution in the third step is water in a supercritical state.

により By the above means of the present invention, it is possible to provide a method for producing vanadium dioxide-containing particles capable of obtaining an optical film having low haze and excellent thermochromic properties.

機構 The production mechanism and action mechanism that can solve the above-mentioned problems under the manufacturing conditions specified by the present invention are estimated as follows.

When producing vanadium dioxide-containing particles by a hydrothermal synthesis method, for example, if the slurry raw material liquid composed of a vanadium-containing compound, an alkaline agent, etc. is in a state containing a large amount of salts, the salts are converted into water. Controlling the particle structure during thermal synthesis, particularly affecting the formation of crystallites, made it difficult to obtain vanadium dioxide-containing particles having a desired particle profile.

Therefore, as a result of studying each condition in the desalting treatment, in the desalting treatment step, salts in the slurry raw material liquid are excessively removed, for example, the electric conductivity of the slurry raw material liquid is reduced to about 1 mS / m. The environment for forming particles during hydrothermal synthesis is improved, the crystallite size of vanadium dioxide-containing particles can be adjusted, and during hydrothermal synthesis, for example, when using a flow-through reactor, a flow path due to particle aggregation or the like is used. This has the advantage that it is possible to prevent clogging and to improve continuous productivity, but it has been found that it has the following problems.

That is, excessive desalting of the slurry raw material liquid, removing most of the salts, with a decrease in the salt concentration, the solubility of the vanadium-containing precursor particles increases, the dissolution of the fine particles in the desalination process step and large Growth into particles, so-called Ostwald ripening, progresses, and the finally obtained particles have advanced crystal growth, and have a large average particle diameter and a large average crystallite diameter. Therefore, in the application of an optical film that requires high quality characteristics, it causes a rise in haze and a decrease in optical performance, and therefore, at present, there is room for improvement.

As a result of further detailed examination of the desalting treatment conditions, the present inventor found that the slurry raw material liquid at the time of desalination treatment had a pH at 25 ° C. of 8.0 to 11.0. By performing the desalting treatment while keeping the electric conductivity at 25 ° C. within the specific condition range of 10 to 1000 mS / m, the average primary order can be prevented without causing the above-described coarsening of the particles. Highly monodisperse vanadium dioxide-containing particles having a particle size in the range of 1 to 30 nm and an average crystallite size in the range of 1 to 15 nm can be obtained, and as a result, formation of aggregates (secondary particles) Is suppressed, the particle size distribution is narrow, the vanadium dioxide-containing particles having a small average particle size and excellent dispersion stability, and a low haze to which it is applied, and an optical film with excellent thermochromic properties can be obtained. Speculate that.

Note that the above technical mechanisms are merely speculations and do not limit the technical scope of the present invention.

Process flow chart showing an example of a production process of vanadium dioxide-containing particles having a desalination treatment step of the present invention The schematic diagram which shows an example of the processing flow of the ultrafiltration apparatus which is an example of the desalination apparatus applicable to the desalination processing step which concerns on this invention. Schematic showing an example of a production flow including a hydrothermal reaction section applicable to the production of vanadium dioxide-containing particles according to the present invention. Schematic showing an example of a flow-type reaction apparatus equipped with a hydrothermal reaction section applicable to the production of vanadium dioxide-containing particles according to the present invention. Schematic diagram showing an example of the particle structure (crystallite diameter) of vanadium dioxide-containing particles specified by the production method according to the present invention.

The method for producing vanadium dioxide-containing particles of the present invention is a method for producing vanadium dioxide-containing particles using a flow-type reaction apparatus having a hydrothermal reaction section, comprising at least the first to third steps described above, In the second step, the pH of the slurry raw material liquid at 25 ° C. is set within a range of 8.0 to 11.0, the electric conductivity at 25 ° C. is maintained within a range of 10 to 1000 mS / m, and the vanadium dioxide is added. It is characterized in that the particles are produced by adjusting the average primary particle diameter of the contained particles to be in the range of 1 to 30 nm and the average crystallite diameter in the range of 1 to 15 nm. This feature is a technical feature common to or corresponding to each of the following embodiments.

As an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, the use of an ultrafiltration device as the desalting treatment for removing salts from the slurry raw material liquid can efficiently perform the desalting treatment. Is preferred.

(4) It is preferable that the desalting treatment for removing salts from the slurry raw material liquid is performed at a liquid temperature of 30 ° C. or lower in that the desalting treatment can be performed more efficiently.

水 Further, it is preferable that the water constituting the reaction solution is water in a supercritical state in that high-quality vanadium dioxide-containing particles can be stably produced.

Hereinafter, the present invention, its components, and embodiments and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning including the numerical value described before and after it as a lower limit and an upper limit. In the description of each drawing, the numbers described at the end of the constituent elements represent the reference numerals described in the drawings to be described. In addition, the dimensional ratios in the drawings are exaggerated for convenience of description, and may be different from the actual ratios.

<< Method for producing vanadium dioxide-containing particles >>
First, an overall outline of the method for producing vanadium dioxide-containing particles of the present invention will be described.

The method for producing vanadium dioxide-containing particles of the present invention is a method for producing vanadium dioxide-containing particles using a flow reactor having a hydrothermal reaction section,
It has at least the following first to third steps:
First step: a step of preparing a slurry raw material liquid containing at least a vanadium-containing compound, a reaction modifier, and water Second step: a step of subjecting the slurry raw material liquid to a desalting treatment Third step: applying the desalting treatment A step of producing vanadium dioxide-containing particles by a hydrothermal reaction method using a reaction liquid obtained by mixing a slurry raw material liquid and water in a supercritical or subcritical state,
In the second step, the pH of the slurry raw material liquid at 25 ° C. is in the range of 8.0 to 11.0,
Maintaining the electrical conductivity at 25 ° C. within the range of 10 to 1000 mS / m;
The average primary particle diameter of the vanadium dioxide-containing particles is in the range of 1 to 30 nm, and
It is characterized by being manufactured by adjusting the average crystallite diameter so as to be in the range of 1 to 15 nm.

In the present invention, “vanadium dioxide (VO ₂ ) -containing particles” are also referred to as “vanadium dioxide-containing particles according to the present invention”, “VO ₂ -containing particles according to the present invention”, or simply “VO ₂ -containing particles”.

In the present invention, a method of forming a vanadium dioxide-containing particle by a hydrothermal reaction between a slurry raw material liquid containing a desalted vanadium-containing compound and supercritical or subcritical water is referred to as `` hydrothermal. '' Also referred to as “synthesis method”, “hydrothermal reaction method”, or “hydrothermal reaction”, the step of performing the hydrothermal reaction is referred to as “hydrothermal reaction step”, and specifically, FIG. 3 and FIG. An apparatus for continuously performing a hydrothermal reaction as shown in FIG. 4 is referred to as a “flow-type reaction apparatus”.

[Basic production flow of vanadium dioxide-containing particles]
FIG. 1 is a flowchart showing an example of the method for producing vanadium dioxide-containing particles of the present invention having a desalination treatment step.

(4) In the method for producing vanadium dioxide-containing particles, as a first step, a slurry raw material liquid is prepared. The slurry raw material liquid according to the present invention includes (A) a raw material liquid containing a vanadium-containing compound and water, (B) a reaction modifier (for example, an alkali), and (C) water (preferably an ion (Exchange water), and various additives are added as needed.

２ In the second step, desalting treatment is performed on the slurry raw material liquid prepared above to remove unnecessary salts (for example, calcium ions) from the slurry raw material liquid. At this time, the slurry raw material liquid is characterized in that the pH at 25 ° C. is in the range of 8.0 to 11.0 and the electric conductivity at 25 ° C. is in the range of 10 to 1000 mS / m. Although there is no particular limitation on the desalting method, a decantation method, a centrifugal separation method, an ultrafiltration method and the like can be applied, and among them, the ultrafiltration method is particularly preferable. In the present invention, the pH of the slurry raw material liquid can be easily measured using a commercially available pH meter, and the electric conductivity can also be easily measured using a commercially available electric conductivity meter. At this time, the desalting temperature is preferably 30 ° C. or lower.

Next, as a third step, a "reaction liquid" is prepared by associating a slurry raw material liquid subjected to a desalination treatment with supercritical or subcritical ion exchange water, and then a hydrothermal reactor (for example, FIG. 4), and containing vanadium dioxide having an average primary particle size in the range of 1 to 30 nm and an average crystallite size in the range of 1 to 15 nm. Produce particles.

[Slurry raw material liquid]
First, (1) a vanadium-containing compound, (2) a reaction modifier, and (3) water that constitute a slurry raw material liquid will be described.

[(1) Vanadium-containing compound]
Examples of the vanadium-containing compound (raw material of vanadium dioxide-containing particles) applicable to the present invention include, for example, pentavalent vanadium (hereinafter, referred to as vanadium (V)), and divanadium pentoxide (V) (V Tetravalent vanadium (hereinafter, vanadium) such as ₂ O ₅ ), ammonium vanadate (V) (NH ₄ VO ₃ ), vanadium trichloride (V) (VOCl ₃ ), and sodium vanadate (V) (NaVO ₃ ) (Described as (IV))) as vanadyl oxalate (IV) (VOC ₂ O ₄ ), vanadium oxide sulfate (hereinafter also referred to as vanadyl sulfate) (IV) (VOSO ₄ ), and divanadium tetroxide (IV ) (V ₂ O ₄ ) dissolved in an acid such as sulfuric acid. Note that, among the above vanadium-containing compounds, it is preferable to use tetravalent vanadium (vanadium (IV)) from the viewpoint of forming a slurry-like raw material liquid. Further, the vanadium-containing compound may be used singly or as a mixture of two or more.

The reaction modifier constituting the slurry raw material liquid is not particularly limited as long as it can produce vanadium dioxide-containing particles by hydrothermally reacting the slurry raw material liquid, but tetravalent vanadium (vanadium (IV When)) is applied, an alkali is used.

Specifically, when a tetravalent vanadium (IV) -containing compound is used as the vanadium-containing compound, an alkali is applied as the reaction regulator. At this time, the alkali is added to an aqueous solution containing a vanadium-containing compound and ion-exchanged water.

When a pentavalent vanadium (V) -containing compound is used as the vanadium-containing compound, a reducing agent (for example, hydrazine and a hydrate thereof) is applied as a reaction modifier, but the reaction agent of the present invention is In the method for producing vanadium-containing particles, it is preferable to apply a tetravalent vanadium (IV) -containing compound capable of forming a slurry raw material liquid as the vanadium-containing compound. V) Detailed description of the containing compound and the reducing agent is omitted.

(Tetravalent vanadium (IV) containing compound)
The vanadium (IV) -containing compound (raw material for the vanadium dioxide-containing particles) applied to the method for producing vanadium dioxide-containing particles of the present invention is not particularly limited, and can be appropriately selected from the compounds listed above. Among them, vanadium (IV) oxide (VOSO ₄ ) is preferable from the viewpoint of generating as little by-products as possible after the hydrothermal reaction. The vanadium (IV) -containing compound may be used alone or as a mixture of two or more.

初期 The initial concentration of the vanadium (IV) -containing compound contained in the reaction solution is not particularly limited as long as the intended effects of the present invention can be obtained, but is preferably 0.1 to 1000 mmol / L. With such a concentration, the vanadium (IV) -containing compound is sufficiently dissolved or dispersed, the average primary particle size (particle size) of the obtained vanadium dioxide-containing particles is reduced, and the particle size (particle size) distribution is narrowed. As a result, 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 improved. The initial concentration of the vanadium (IV) compound contained in the reaction solution depends on the average primary 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 of properties and the like, it is more preferably in the range of 20 to 600 mmol / L, and still more preferably in the range of 50 to 400 mmol / L. The “initial concentration” is the amount of the vanadium (IV) -containing compound in 1 L of the reaction solution before the hydrothermal reaction (when two or more vanadium (IV) -containing compounds are contained, the total amount thereof). is there.

[(2) Reaction modifier]
When a vanadium (IV) -containing compound is used as the vanadium-containing compound, it is preferable to use an alkali as a reaction regulator. Further, as described above, when a pentavalent vanadium (V) -containing compound is used as the vanadium-containing compound, a reducing agent (for example, hydrazine and its hydrate) is applied as the reaction modifier.

(alkali)
In the hydrothermal synthesis method (hydrothermal reaction), when the vanadium-containing compound is a vanadium (IV) -containing compound, it is preferable to use an alkali as at least one of the reaction modifiers. The term “alkali” as used in the present invention means a substance that generates hydroxide ions (OH ⁻ ) in an aqueous solution. In addition to a compound that itself generates hydroxide ions, the alkali itself is a hydroxide ion. And compounds that do not result in the formation of a hydroxide ion.

The alkali is not particularly limited, and examples thereof include ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate and the like. The above alkalis can be used alone or in combination of two or more.

中でも Among these, ammonia, sodium hydroxide, or potassium hydroxide is preferable, ammonia or sodium hydroxide is more preferable, and ammonia is more preferable.

The alkali concentration in the slurry raw material liquid composed of the vanadium (IV) -containing compound, alkali and ion-exchanged water is not particularly limited, but is preferably, for example, in the range of 0.01 to 10 mol / L. More preferably, it is in the range of 0.1 to 5 mol / L.

The amount of alkali in the reaction liquid obtained by mixing the slurry raw material liquid and the supercritical or subcritical ion-exchanged water is not particularly limited, for example, a vanadium-containing compound, a compound that reacts with the vanadium-containing compound It is preferable to adjust the pH of the reaction solution composed of ion-exchanged water in a supercritical or subcritical state to be in the range of 6.8 to 11.2, and in the range of 7.0 to 8.5. It is more preferable to adjust within.

[(3) Water for preparing slurry raw material liquid]
The water constituting the slurry raw material liquid is not particularly limited, but it is preferable to use ion-exchanged water or degassed water, and particularly preferable to use ion-exchanged water.

[Other additives]
(Phase transition regulator for vanadium-containing particles)
In the method for producing vanadium dioxide-containing particles of the present invention, in the hydrothermal reaction section, in order to adjust the phase transition temperature of the vanadium-containing compound contained in the reaction solution to the vanadium dioxide-containing particles, a phase transition regulator containing a specific element Can be contained.

Here, the method of adding the phase transition regulator to the reaction solution for controlling the phase transition temperature of the vanadium dioxide-containing particles is not particularly limited, and a known method can be used. As a method of adding to the reaction liquid, it is preferable to add to the slurry raw material liquid containing the vanadium-containing compound. Further, a method of directly adding to the reaction solution before the hydrothermal reaction can also be used.

Here, the phase transition regulator is not particularly limited, but, for example, tungsten, titanium, molybdenum, niobium, tantalum, tin, rhenium, iridium, osmium, ruthenium, germanium, chromium, iron, gallium, aluminum, fluorine, phosphorus For example, a substance containing a metal element other than vanadium can be used. When the reaction solution contains the phase transition regulator, the phase transition temperature of the resulting vanadium dioxide-containing particles can be reduced. Phase Specific examples of transition modifiers can include, for example, ammonium tungstate para pentahydrate _{_{_{_{((NH 4) 10 W 12}}}} O 41 · 5H 2 O) and the like.

[Desalination step]
In the method for producing vanadium dioxide-containing particles of the present invention, a desalting treatment for removing a predetermined amount of salts from the slurry raw material liquid before producing the vanadium dioxide-containing particles by the hydrothermal synthesis method for the slurry raw material liquid prepared above. And maintaining the pH of the slurry raw material liquid at 25 ° C. in the range of 8.0 to 11.0 and the electrical conductivity at 25 ° C. in the range of 10 to 1000 mS / m during the desalting treatment. And performing a desalination treatment.

The desalting treatment means is not particularly limited as long as it can remove salts, for example, ammonium ions, sulfate ions, sodium ions, potassium ions, calcium ions, and the like from the slurry raw material liquid at a predetermined concentration. For example, a filtration method, a centrifugal separation method, an ultrafiltration method, etc. can be applied. Among them, the ultrafiltration method is particularly preferable.

(Centrifugation method)
The centrifugal separation method applicable to desalination treatment involves adjusting the pH of the slurry raw material liquid prepared above, performing solid-liquid separation using a centrifugal separator, and discharging a part of the aqueous separation liquid out of the system. Then, the same volume of ion-exchanged water as that discharged was additionally added, and then dispersion treatment was performed. This operation was repeated to discharge unnecessary salts, and the slurry raw material liquid was subjected to predetermined pH and electric conductivity. Adjust to

(Ultrafiltration method)
Next, a desalination treatment method using an ultrafiltration method, which is a desalting means suitable for the present invention, will be described with reference to the drawings.

FIG. 2 is a schematic diagram showing a processing flow of an ultrafiltration apparatus which is an example of a desalination apparatus used for producing vanadium dioxide-containing particles according to the present invention.

The ultrafiltration device 50 shown in FIG. 2 includes a preparation vessel 51 for storing a slurry raw material liquid 52 and a replenishing pH-adjusting water storing replenishing pH-adjusting water 58 for adjusting the pH to a predetermined value. A stock kettle 57, a replenishing pH-adjusted water supply line 59 for adding replenishing pH-adjusted water 58 to the adjusting kettle 51, a circulation line 53 for circulating the preparation kettle 51 by a circulation pump 54, and a circulation line 53 are removed. In this configuration, an ultrafiltration unit 55, an electric conductivity meter 60, and a pH meter 61 are disposed as salt means.

フロー The flow of the desalination treatment using the ultrafiltration device will be described.

<Step (I)>
The slurry raw material liquid 52 containing the vanadium-containing compound, the compound that reacts with the vanadium-containing compound, and water, prepared by the method described above, is stored in the preparation tank 51, and circulated using the circulation pump 54. In the filtration unit 55, water containing salts in the slurry raw material liquid is discharged from the discharge port 56 at a predetermined discharge amount V1, and concentrated to a predetermined salt concentration.

<Process (II)>
Next, the slurry raw material liquid 52 concentrated in the ultrafiltration unit 55 is discharged from the replenishment pH adjusted water stock tank 57 via the replenishment pH adjusted water supply line 59 through the ultrafiltration unit 55 ( The same volume of replenishing pH-adjusted water 58 as in V1) is added as an added amount V2, and the mixture is sufficiently stirred and mixed to prepare a first desalted slurry raw material liquid 52. At this time, the electric conductivity (mS / m) and pH of the first desalted slurry raw material liquid 52 are measured by the electric conductivity meter 60.

<Process (III)>
Next, in the same manner as in the above step (I), while the primary desalted slurry raw material liquid 52 is circulated by the circulation pump 54, the constituent liquid (ion (Exchanged water + salts) is discharged 56 out of the system at a discharge amount V1.

<Process (IV)>
Next, in the same manner as in the above step (II), the concentrated mixed solution 52 is supplied from the replenishing pH-adjusted water stock kettle 57 to the replenishing pH-adjusted water supply line 59 via the replenishing pH-adjusted water supply line 59 to have the same volume as the discharge amount V1. The replenishing pH-adjusted water 58 is added in an addition amount V2, and sufficiently stirred and mixed to prepare a second desalted slurry raw material liquid 52. At this time, the electric conductivity (mS / m) and pH of the secondary desalted slurry raw material liquid 52 are measured by the electric conductivity meter 60 and the pH meter 61.

The above steps (III) and (IV) are repeated until the electric conductivity (mS / m) of the slurry raw material liquid 52 reaches a desired condition, thereby preparing a desalted slurry raw material liquid 52. I do. In addition, when there is a difference between a predetermined pH and a predetermined pH, finally, an acid or an alkali for pH adjustment is added and adjusted.

限 As an ultrafiltration method used in the above desalting treatment step, for example, the method described in Research Disclosure No. 10208 (1972); 13122 (1975); 16351 (1977).

圧力 The pressure difference and flow rate that are important as operating conditions can be set with reference to the characteristic curve described in “Handbook of Membrane Utilization Technology” by Haruhiko Oya, Koshobo Publishing (1978), p.275.

As the ultrafiltration membrane, as the membrane material, as the organic membrane, a flat plate type, a spiral type, a cylindrical type, a hollow fiber type, a hollow fiber type, etc. already incorporated as a module are available from Asahi Kasei Corporation, Daicel Chemical Co., Ltd., ( Although commercially available from Toray Industries, Inc., Nitto Denko Corporation, etc., ceramic membranes such as NGK Insulators Co., Ltd. and Noritake Co., Ltd. are preferred as the solvent-resistant membrane.

More specifically, for example, ultrafiltration is performed at a flow rate of 300 ml / min (min), a liquid pressure of 100 kPa, and room temperature using Vivaflow 50 (effective filtration area: 50 cm ² , molecular weight cut off: 5000) manufactured by Sartorius stemim as a filtration membrane. Examples thereof include an ultrafiltration device (Pellicon 2 cassette manufactured by Nippon Millipore Co., Ltd.) having a filtration membrane made of polyethersulfone and having a molecular weight cut off of 300,000.

(Hydrothermal reactor)
In the method for producing vanadium dioxide-containing particles, a slurry raw material liquid subjected to the above desalting treatment and having a predetermined electric conductivity and pH adjusted is subjected to hydrothermal synthesis in the next step as shown in the flow chart of FIG. And producing vanadium dioxide-containing particles having an average primary particle size in the range of 1 to 30 nm and an average crystallite size in the range of 1 to 15 nm.

The conditions of the hydrothermal reaction treatment (eg, the amount of the reactant, the treatment temperature, the treatment pressure, the treatment time, etc.) are appropriately set, but the temperature of the hydrothermal reaction treatment is, for example, in the range of 300 to 500 ° C. , Preferably within the range of 350 to 400 ° C. By setting the temperature within the above range, it is possible to reduce the average primary particle size (D) and the like and to narrow the particle size distribution while avoiding the possibility that the crystallinity is lowered. The time of the hydrothermal reaction is not particularly limited, but is preferably in the range of 3 to 1000 seconds. Under the above conditions, it is possible to efficiently produce vanadium dioxide-containing particles having a narrow particle diameter distribution and a small particle diameter. Further, the possibility that the crystallinity of the vanadium dioxide-containing particles is reduced can be avoided. 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 according to the present invention is preferably performed with stirring. By stirring, the vanadium dioxide-containing particles can be prepared more uniformly.

In the method for producing vanadium dioxide-containing particles of the present invention, the hydrothermal reactor is preferably subcritical or supercritical using a flow-type reactor equipped with a flow-type reactor such as a pressure-resistant tube type or tank type. This is a method of continuously synthesizing by mixing with high-temperature and high-pressure water in a critical state. In particular, a flow-type reaction apparatus using a tubular reactor can be suitably used.

(Flow type reactor)
In the method for producing vanadium dioxide-containing particles of the present invention, it is particularly preferable that the hydrothermal reaction is performed using a flow-type reactor having a hydrothermal reaction section.

Hereinafter, an embodiment in which a hydrothermal reaction is performed using a suitable flow-type reaction apparatus in the method for producing vanadium dioxide-containing particles of the present invention will be described. Note that the present invention is not limited to only the embodiments described below.

流通 The flow reactor according to the present invention is a flow reactor equipped with a hydrothermal reactor. The term “hydrothermal reaction section” as used herein refers to a mixing and reactor that realizes high-speed mixing and reaction under high-temperature and high-pressure conditions.

In the hydrothermal reaction section, under high pressure, in the presence of deionized water in a supercritical or subcritical state, by performing a hydrothermal reaction on the deaerated raw material slurry liquid, excellent vanadium dioxide-containing particles Vanadium dioxide-containing particles having high thermochromic properties and high monodispersity can be produced, and the transparency of the optical film can be achieved. This is because the hydrothermal reaction is performed under high pressure in the presence of ion exchange water in a supercritical or subcritical state, thereby suppressing the oxidizing atmosphere during the hydrothermal reaction and vanadium dioxide having a desired particle profile. Can be produced by a stable reaction, and vanadium dioxide (VO ₂ ) -containing particles having thermochromic properties can be produced stably.

When performing a hydrothermal reaction using a flow-type reaction device, in the present invention, in the hydrothermal reaction unit performing the hydrothermal reaction of the flow-type reaction device, a vanadium-containing compound subjected to desalination treatment, a vanadium-containing compound and The passage time of a reaction solution obtained by mixing a slurry raw material solution containing a compound to be reacted and ion-exchanged water with ion-exchanged water in a supercritical or subcritical state is in the range of 4 to 700 seconds, and more preferably 12 to 700 seconds. It is preferable to be within the range of seconds.

Next, a specific configuration of a flow-type reaction apparatus applicable to the method for producing vanadium dioxide-containing particles of the present invention will be described with reference to the drawings.

FIG. 3 shows an example of a production flow of a flow reactor having a hydrothermal reaction section suitable for the method for producing vanadium dioxide-containing particles of the present invention.

As shown in FIG. 3, the desalted slurry raw material liquid container 5 contains 1) a vanadium-containing compound, 2) a compound that reacts with the vanadium-containing compound, for example, an alkali dissolved at a predetermined concentration in ion-exchanged water. 3) A salt-treated slurry raw material liquid composed of ion-exchanged water is charged, and ion-exchanged water is stored in the other raw material liquid container 2 as water. , Under pressure, ion-exchanged water in a supercritical or subcritical state, and after associating the two at the confluence point MP to form a reaction solution, the heating unit in the hydrothermal reaction unit 16 constituting the hydrothermal reaction unit In this method, vanadium dioxide-containing particles are prepared by performing a hydrothermal treatment in a pipe 17. At this time, the reaction liquid after mixing is maintained in a supercritical or subcritical state until a hydrothermal reaction is performed.

FIG. 4 is a schematic view showing an example of a flow-type reaction apparatus having a hydrothermal reaction section, which is applicable to the production of vanadium dioxide-containing particles according to the present invention.

In FIG. 4, a flow-type reaction apparatus 1 having a hydrothermal reaction section 16 has a desalted pH at 25 ° C. containing a vanadium-containing compound, a compound that reacts with the vanadium-containing compound, and ion-exchanged water. The slurry raw material container 5 for holding a slurry raw material liquid having a conductivity of 8.0 to 11.0 and an electric conductivity at 25 ° C. of 10 to 1000 mS / m, and a supercritical liquid as the other constituent liquid An ion-exchanged water container 2 for containing ion-exchanged water for forming water or subcritical water, a hydrothermal reactor 16 having a heating medium 14 for performing a hydrothermal reaction, a tank 9 for containing a reaction solution after the hydrothermal reaction , A slurry raw material container 5, flow paths 3 and 6 (piping) for connecting the ion-exchanged water container 2 and the tank 9 respectively, and one of the desalted slurry raw material liquids into a slurry raw material liquid container. From the pipe 6, the confluence point MP, the heating section pipe 17, the pipe 18 and the control valve 19, the pump 7 for sending the liquid to the tank 9, and the other constituent liquid, which is stored in the ion exchange water container 2. Ion-exchanged water for forming supercritical water or subcritical water is supplied from the ion-exchanged water container 2 through the pipe 3, the heating medium 13, the junction MP, the heating section pipe 17, the pipe 18, and the control valve 19. Then, the pump 4 for sending the liquid to the tank 9 is arranged.

The flow-type reactor 1 may be provided with a cooling unit 8 having a flow channel 18 for cooling a reaction solution containing vanadium dioxide-containing particles after the hydrothermal reaction, if necessary. In addition, although details will be described later, if necessary, added to the reaction solution containing the vanadium dioxide-containing particles after the hydrothermal reaction, for example, a surface modifier, a pH adjuster, or the reaction solution after the hydrothermal reaction A tank 10 for containing a cooling medium (for example, water) for mixing and cooling, a surface modifier, a pH adjuster, a cooling medium, and the like are sent to a flow path 18 via a flow path 11. May be provided.

The flow reactor 1 has

heating media

13 and 15 in the line of the flow path 6 or the flow path 3. In particular, the heating medium 13 disposed in the flow path 3 applies a predetermined temperature and pressure to the ion exchange water stored in the ion exchange water container 2 to form supercritical water or subcritical water. .

In addition, a vanadium-containing compound, a slurry raw material liquid containing a compound that reacts with the vanadium-containing compound, and ion-exchanged water, a hydrothermal reaction section 16 through which a reaction liquid after the hydrothermal reaction flows, a heating section pipe 17, a flow path 3, The material of the piping constituting 6, 11, 18 and the like is not particularly limited, and examples thereof include stainless steel, aluminum, iron, and Hastelloy.

The line length L of the heating section pipe 17 of the heating section pipe 17 formed inside the hydrothermal reaction section 16 is not particularly limited, and the vanadium-containing compound, the compound that reacts with the vanadium-containing compound, It is sufficient that the reaction solution is composed of a critical or subcritical ion-exchanged water and pass through within a time of 3 to 1000 seconds.

Further, the speed (flow rate) of the reaction solution passing (flowing) through the heating section pipe 17 in the hydrothermal reaction section is not particularly limited, but is preferably 0.1 to 10 m / sec, more preferably 0.2 to 8 m / sec. 0.0 m / sec. With such a flow rate, the vanadium-containing compound contained in the reaction solution and the compound that reacts with the vanadium-containing compound are subjected to a hydrothermal reaction in the presence of supercritical or subcritical ion-exchanged water under a predetermined condition. Can be implemented effectively.

The line length L of the heating part pipe 17 in the present invention is defined as the line length L of the pipe part from the inlet IN of the heating medium 14 through the junction point MP to the outlet OUT of the heating medium 14 after the hydrothermal treatment. Refers to the length.

In the present invention, the passage time of the reaction liquid in the heating section piping 17 which is a hydrothermal reaction section is determined by the above-mentioned flow rate of the reaction liquid and the line length L of the heating section piping. Desired conditions can be obtained by controlling the pressure and the flow rate according to the liquid sending pressure of the pumps 4 and 7 installed in (3 and 6) and the inner diameter of each flow path.

In addition, the lengths of the

flow paths

3 and 6 for feeding the raw material liquid, the flow path 11 for sending the refrigerant or the surface modifier added to the reaction liquid after the hydrothermal reaction, and the flow path 18 for cooling the reaction liquid are set forth. The length is not particularly limited, but is generally in the range of 50 to 10000 mm, and preferably in the range of 100 to 1000 mm. The gap (inner diameter in the case of piping) of the flow channel is not particularly limited, but is generally in the range of 0.1 to 10 mm, preferably in the range of 1.0 to 8 mm.

The

pipes

3, 6, 11 and 18 preferably have the above-mentioned materials, lengths and inner diameters, but may be the same or different.

The reaction solution after the hydrothermal reaction obtained in the above-described hydrothermal reaction step is subjected to filtration (for example, ultrafiltration) or centrifugation to replace the dispersion medium or the solvent, and to convert the vanadium dioxide-containing particles into water or alcohol ( For example, it may be washed with ethanol) or the like. The obtained vanadium dioxide-containing particles may be dried by any means. In addition, TC shown in FIG. 4 is a temperature sensor.

(Hydrothermal reaction conditions: temperature, pressure)
In the present invention, by performing the hydrothermal reaction under the conditions described above, the average primary particle size and the average crystallite size of the formed vanadium dioxide-containing particles can be controlled to desired conditions, and the vanadium dioxide-containing particles can be controlled. The thermochromic properties of the particles and the transparency of the optical film containing the particles containing vanadium dioxide can be improved (reduction in haze).

Regarding these excellent effects, the detailed mechanism is unknown, but it is achieved by suppressing the crystal growth of precipitated vanadium dioxide microcrystals by the hydrothermal reaction under the conditions shown above. Guessed.

In the hydrothermal reaction section according to the present invention, the water in a high temperature and high pressure state is a high temperature and high pressure water in a supercritical or subcritical state, that is, supercritical water (SCW) or subcritical water (sub). -Critical @ water: sub-CW). Since the critical temperature of water is 374.2 ° C. and the critical pressure of water is 22.12 MPa, water having the temperature and pressure higher than the temperature is referred to as supercritical water. In addition, subcritical water refers to water in a state where the temperature or pressure is slightly lower than the supercritical point of water, and for example, from a temperature range of 200 ° C. or more to a critical temperature of 374 ° C. Refers to a region where the temperature is lower than the critical temperature of water and the pressure is a critical pressure of water of 22 MPa or more.

A typical supercritical water region is, for example, 375-500 ° C., preferably 375-450 ° C., more preferably 375-420 ° C., even more preferably 375-400 ° C., and in some cases, for example, 375-400 ° C. To 395 ° C., preferably 375 to 390 ° C., more preferably 375 to 385 ° C. or 375 to 380 ° C., and the reaction pressure is, for example, 22 to 50 MPa, preferably 22 to 45 MPa, Preferably it is in the range of 22 to 40 MPa, more preferably 25 to 35 MPa.

A typical subcritical water region has a pressure of a critical pressure of 22 MPa or more and a temperature region from a temperature of 150 ° C. or more to a critical temperature of 374 ° C., or a temperature of 200 ° C. or more to a critical temperature of 374 ° C. Or a region from a temperature of 250 ° C. or more to a critical temperature of 374 ° C., a region of a temperature from 300 ° C. or more to a critical temperature of 374 ° C., and the like. Of course, the subcritical water region is a region from a pressure of 10.0 MPa or more to a critical pressure of 22 MPa, or a region from a pressure of 15.0 MPa or more to a critical pressure of 22 MPa, or a pressure of 18.0 MPa or more to a critical pressure. A region up to 22 MPa or a region from a pressure of 20.0 MPa or more to a critical pressure of 22 MPa may be included.

As described above, there are various definitions of subcritical water. In the present invention, water in a temperature range of 200 to 373 ° C. and a pressure range of 5.0 to 50 MPa is referred to as subcritical water. Is defined.

The temperature and pressure conditions in the hydrothermal reaction are not particularly limited as long as they are in the range of 150 to 500 ° C. and the pressure is higher than the saturated vapor pressure as described above. More preferably, the temperature is in the range of 500 ° C., the pressure is in the range of 10 to 40 MPa, and the pressure is higher than the saturated vapor pressure at the set temperature. When the temperature is 300 ° C. or higher, the average primary particle size (D) and the like can be further reduced while avoiding the possibility that crystallinity is lowered. Further, when the temperature is 500 ° C. or lower, the particle size distribution can be narrowed. From the same viewpoint, it is more preferable that the temperature is in the range of 350 to 450 ° C., the pressure is in the range of 20 to 40 MPa, and the pressure is higher than the saturated vapor pressure at the set temperature. More preferably, the hydrothermal reaction is performed in the presence of supercritical water at a temperature in the range of 380 to 400 ° C. and a pressure in the range of 25 to 30 MPa.

において In the present invention, the hydrothermal reaction time is not particularly limited, but is preferably in the range of 3 to 1000 seconds. Under the above conditions, particles containing vanadium dioxide having a narrow particle size distribution and a small particle size can be efficiently produced. Further, the possibility that the crystallinity of the vanadium dioxide-containing particles is reduced can be avoided. 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 according to the present invention is preferably performed with stirring. By stirring, the vanadium dioxide-containing particles can be prepared more uniformly.

(Cooling process)
In the method for producing vanadium dioxide-containing particles of the present invention, in addition to the above-described hydrothermal reaction step, a cooling step of cooling the reaction solution after hydrothermal reaction (a dispersion containing vanadium dioxide-containing particles) (FIG. 4) It is preferable to further include a cooling unit 8) indicated by the following.

In the cooling step, it is preferable to start cooling the reaction solution after the hydrothermal reaction within one minute after performing the hydrothermal reaction for a predetermined time (at the end of the reaction), but the entire reaction solution is cooled within this time. If it is difficult, the reaction solution may be cooled by a predetermined amount while keeping the reaction solution at a reaction temperature with a certain amount of time.

冷却 In this step, the cooling rate can be appropriately adjusted.

(4) The method of cooling the reaction solution after the hydrothermal reaction is not particularly limited, and can be applied in the same manner as a known method or by appropriately changing it. As a cooling method, for example, a method of immersing the reaction solution after the hydrothermal reaction in a cooling medium with stirring if necessary, a method of mixing the reaction solution after the hydrothermal reaction with the cooling medium (particularly water), A method of passing a gaseous cooling medium (for example, liquid nitrogen) through the reaction solution after the hydrothermal reaction may be used. Among these, the method of bringing the reaction liquid after the hydrothermal reaction and the cooling medium into contact with each other via a pipe is preferable as illustrated in FIG. 4 because the cooling rate can be easily controlled. Here, at least in the flow-type reaction apparatus 1, it is preferable that the cooling is performed by using the cooling unit 8 connected to the hydrothermal reaction unit 16 directly or via another component.

A description will be given of a cooling method using the cooling unit 8 connected to the hydrothermal reaction unit 16 and having the flow path 18 therein in the flow-type reaction device 1. Note that the cooling method that can be used in the present invention is not limited to the mode described below.

As the cooling method according to the present invention, it is preferable that the reaction solution after the hydrothermal reaction is cooled by passing (flowing) through the flow channel 18 of the flow-type reaction device 1. That is, as an example of the flow-type reaction device 1 shown in FIG. 4, the reaction liquid containing vanadium dioxide-containing particles is passed (flowed) through the flow channel 18 of the cooling unit 8 on the downstream side of the hydrothermal reaction unit 16. To perform cooling. The cooling medium C flows into the cooling unit 8 and cools the flow channel 18 from the outer surface.

Further, as another method, for the purpose of cooling by mixing with a cooling medium (for example, water), in the flow-type reaction apparatus 1, as described above, the tank 10 may be replaced with the above-described surface modifying agent or pH adjustment. Instead of the method used for adding the agent, or by separately providing a similar addition line, the cooling medium may be directly added. At this time, a pump 12 for flowing the cooling medium through the flow path 11 may be further provided.

In this case, the cooling medium may be used as a cooling medium having a pH adjusting effect when the pH adjusting agent is dissolved in water or the like as the medium.

混合 When a cooling medium is used, the mixing ratio of the cooling medium with the reaction solution 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) as compared with the reaction solution after the hydrothermal reaction. The mixing ratio can be controlled by setting the flow rates of the reaction liquid and the cooling medium after the hydrothermal reaction to the above-described ratios.

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

When a cooling medium is used, the pH of the mixture of the reaction solution after the hydrothermal reaction and the cooling medium (preferably water) is not particularly limited, but is in the range of 4.0 to 7.0 at 25 ° C. It is preferred that By setting the pH within the above range, the stability of the vanadium dioxide-containing particles after particle formation (crystal precipitation) can be improved. Therefore, the purity of the desired rutile-type crystal phase (R phase) vanadium dioxide can be further improved, and the thermochromic properties of the vanadium dioxide-containing particles can be more effectively improved. Means for achieving such a pH value is not particularly limited, and may be achieved by adding the above-described pH adjuster to the reaction solution after the hydrothermal reaction before the cooling step. This may be achieved by using a cooling medium mixed with the conditioning agent.

In the case where a cooling medium is used, the mixing position of the reaction liquid after the hydrothermal reaction and the cooling medium (the installation position of the pipe 11) is not particularly limited, but considering the cooling efficiency of the reaction liquid after the hydrothermal reaction and the like. The pipe 11 is preferably connected to the heating section pipe 17 at a distance of 10 to 500 mm from the outlet on the tank 9 side.

反応 The cooled reaction liquid (cooling liquid) after the hydrothermal reaction is stored in the tank 9 via the control valve 19. After storage, the dispersion medium and the solvent may be replaced by filtration (eg, ultrafiltration) or centrifugation, and the vanadium dioxide-containing particles may be washed with water, alcohol (eg, ethanol), or the like. Further, the obtained vanadium dioxide-containing particles may be dried by any means.

[Other additives]
In the method for producing vanadium dioxide-containing particles of the present invention, various additives can be applied, if necessary, in addition to the vanadium-containing compound and the compound (alkali) that reacts with the vanadium-containing compound.

代表 The following typical additives will be described.

(Surface modifier)
In the method for producing vanadium dioxide-containing particles of the present invention, a surface modifier is further added to the reaction solution containing the vanadium dioxide-containing particles immediately after the hydrothermal reaction from the tank 10 shown in FIG. Can be added.

By adding a surface modifier to the reaction solution containing the vanadium dioxide-containing particles formed by the hydrothermal reaction, aggregation of the vanadium dioxide-containing particles is effectively suppressed and prevented, and the size (particle diameter) of the vanadium dioxide-containing particles is reduced. The dispersion stability and storage stability of the vanadium dioxide-containing particles can be further improved by reducing the particle size and narrowing the particle size distribution. Therefore, haze due to the vanadium dioxide-containing particles is reduced, and thermochromic properties can be effectively exhibited.

表面 Examples of the surface modifier that can be provided in the present invention include organic silicon compounds, organic titanium compounds, organic aluminum compounds, organic zirconia compounds, surfactants, and silicone oils. The number of reactive groups in the surface modifier is not particularly limited, but is preferably 1 or 2.

<Organosilicon compound>
Specific examples of the surface modifier applicable to the present invention include organosilicon compounds (organic silicate compounds), such as hexamethyldisilazane, trimethylethoxysilane, trimethylmethoxysilane, tetraethoxysilane (tetraethylorthosilicate), and trimethylsilyl. Chloride, methyltriethoxysilane, dimethyldiethoxysilane, decyltrimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3- Aminopropyltriethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane 3-glycidoxypropyl methyldimethoxysilane, and the like. In addition, the organosilicon compound can be obtained as a commercial product, and for example, SZ6187 (manufactured by Dow Silicone Toray) can be suitably used.

Among these organosilicon compounds, it is preferable to use an organic silicate compound having a small molecular weight and high durability, and in particular, to use hexamethyldisilazane, tetraethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, and trimethylsilyl chloride. Is more preferred.

<Organic titanium compound>
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, and bis (dioctyl pyrophosphate) oxy Acetate titanate, as a chelate compound, titanium acetylacetonate, titanium tetraacetylacetonate, titanium ethyl acetoacetate, titanium phosphate compound, titanium octylene glycolate, titanium ethyl acetoacetate, titanium lactate ammonium salt, titanium lactate, titanium triethanol Aminates and the like. In addition, the organic titanium compound can be obtained as a commercial product, and examples thereof include Prenact TTS and Prenact TTS44 (all manufactured by Ajinomoto Fine Techno Co., Ltd.).

<Organic aluminum compound>
Examples of the organic aluminum compound include aluminum isopropoxide and aluminum tert-butoxide.

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

<Surfactant>
Surfactants are compounds 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 carbonyl group, an ester group, an amino group, an amide group, an ammonium salt, a thiol, a sulfonate, and a phosphate. And a polyalkylene glycol group. 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 of each group. More specifically, examples of such a surfactant include myristyldiethanolamine, 2-hydroxyethyl-2-hydroxydodecylamine, 2-hydroxyethyl-2-hydroxytridecylamine, and 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 oils such as dimethyl silicone oil, methylphenyl silicone oil, and methyl hydrogen silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, carrubinol-modified silicone oil, and methacryl-modified silicone oil. Silicone oil, mercapto-modified silicone oil, heterofunctional group-modified silicone oil, polyether-modified silicone oil, methylstyryl-modified silicone oil, hydrophilic specially-modified silicone oil, higher alkoxy-modified silicone oil, higher fatty acid-containing modified silicone oil and fluorine-modified silicone And the like.

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. Further, the number of carbon atoms in the organic functional group introduced by the surface modifier is preferably 1 to 6. Thereby, durability can be improved. The solution containing the surface modifying agent may be adjusted to an appropriate pH value (for example, 2 to 12) using a pH adjusting agent. Here, the pH adjuster is not particularly limited, and the same pH adjusters as described below can be used.

When the surface modifier is used, the amount of the surface modifier is not particularly limited, but is in the range of 0.1 to 100% by mass based on the mass of the vanadium dioxide-containing particles obtained by the hydrothermal reaction. Preferably, it is more preferably in the range of 1 to 10% by mass.

添加 From the viewpoint of modifying the surface of the vanadium dioxide-containing particles, the addition of the surface modifier is preferably started immediately after the hydrothermal reaction (immediately after the end of the reaction). Specifically, the addition is preferably performed within 10 seconds from the end of the reaction, and more preferably within 5 seconds.

方法 The method for adding the surface modifier is not particularly limited, and a known method can be used. For example, when the flow-type reaction device 1 shown in FIG. 4 is used, a surface modifier (or a solution containing the surface modifier) is supplied from the tank 10 to the reaction solution immediately after the hydrothermal reaction by the pump 12. By joining the heating unit piping 17 via the heating unit 11, it can be mixed with the reaction solution.

The speed at which the solution containing the surface modifier passes (flows) through the flow channel 11 (flow speed) is not particularly limited, but is preferably in the range of 0.01 to 10 mL / sec, more preferably 0.1 to 10 mL / sec. Within the range of 5 mL / sec.

With such a flow rate, the surface modifier is brought into sufficient contact with the vanadium dioxide-containing particles and the effect of the surface modifier (coagulation suppression effect of particles, Dispersion stability and storage stability).

The mixing position of the reaction solution after the hydrothermal reaction and the surface modifying agent (the installation position of the pipe 11) is not particularly limited, but the addition of the surface modifying agent is started immediately after the hydrothermal reaction. It is preferable to dispose it immediately after the outlet B. In the case where the cooling unit 8 is provided after the hydrothermal reaction unit 16 as in the flow-type reactor 1, the cooling unit 8 is disposed immediately after the hydrothermal reaction unit 16 and before the cooling unit 8 as shown in FIG. Is preferred.

In the case where a pH adjuster described later and a cooling medium in a cooling step described later are used together with the surface modifier, another line including the tank 10, the flow path 11, and the pump 12 may be separately provided.

(PH adjuster)
In the method for producing vanadium dioxide-containing particles using a flow-type reactor, a pH adjuster can be further added to the reaction solution immediately after the hydrothermal reaction from the tank 10 via the flow path 11.

The pH adjuster is not particularly limited. 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, etc. is used. Can be.

PH of the reaction solution after the hydrothermal reaction, the particle size of the vanadium dioxide-containing particles, particle size distribution, from the viewpoint of the transparency of the optical film containing the vanadium dioxide-containing particles thermochromic and vanadium dioxide-containing particles, at 25 ℃ , Preferably in the range of 3.0 to 10.0, more preferably in the range of 4.0 to 9.0. The pH adjuster may be the same as or different from the alkali and the reducing agent used as the compound that reacts with the vanadium-containing compound in the hydrothermal reaction.

It is preferable that the pH adjuster 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.

方法 The method of adding the pH adjuster is not particularly limited, and a known method can be used. For example, when the flow-type reaction device 1 shown in FIG. 4 is used, a pH adjusting agent (or a solution containing the pH adjusting agent) is flowed from the tank 10 to the reaction solution immediately after the hydrothermal reaction by the pump 12. 11 and can be mixed with the reaction solution.

The mixing position of the reaction solution after the hydrothermal reaction and the pH adjusting agent (position where the flow channel 11 is installed) is not particularly limited, but from the viewpoint of starting the addition of the surface modifier after the hydrothermal reaction, Preferably, it is arranged after the part 16. In the flow-type reaction device 1 shown in FIG. 4, when the cooling unit 8 is provided after the hydrothermal reaction unit 16, the cooling unit 8 may be disposed after the hydrothermal reaction unit 16 and before the cooling unit 8. Alternatively, it may be arranged after the cooling unit 8 and before the tank 9.

When the above-mentioned surface modifier and the cooling medium in the cooling step described below are used together with the pH adjusting agent, the supply lines including the tank 10, the flow path 11, and the pump 12 may be individually provided. . Alternatively, a method may be used in which a pH adjuster and a surface modifier, or a pH adjuster and a cooling medium are mixed and supplied through one supply line.

Further, when the addition of the pH adjuster is performed before the cooling step described below, these additions shall be included in the hydrothermal reaction step, and when performed after the cooling step described below, the cooling It shall be included in the process.

(Vanadium dioxide-containing particle profile)
In the method for producing vanadium dioxide-containing particles of the present invention, the average primary particle diameter of the produced vanadium dioxide-containing particles is in the range of 1 to 30 nm, and the average crystallite diameter is in the range of 1 to 15 nm. Features.

平均 The average primary particle diameter of the particles containing vanadium dioxide is characterized by being in the range of 1 to 30 nm, preferably in the range of 1 to 20 nm. With the particles containing vanadium dioxide having such a particle diameter, haze can be reduced favorably and thermochromic properties can be effectively exhibited. The particle diameter of the vanadium dioxide-containing particles can be measured by an electron microscope observation or a particle diameter measuring method based on a dynamic light scattering method.

(4) When electron microscopy is used to measure the particle size of the vanadium dioxide-containing particles, the particle size can be measured using a scanning electron microscope (Hitachi S-5000, manufactured by Hitachi, Ltd.). In the present invention, the average primary particle diameter (D) (nm) of the vanadium dioxide-containing particles can be measured by the following method.

(4) The dispersion containing the particles containing vanadium dioxide and water is dried and solidified in an oven at 120 ° C. to obtain a powder, and a particle sample for measurement is prepared.

Next, using the obtained particle sample, an SEM photograph is taken with a scanning electron microscope (Hitachi S-5000, manufactured by Hitachi, Ltd.). The particle diameter is calculated using an SEM photograph (1100 nm × 950 nm). Here, the particle diameter means an area circle equivalent diameter. Specifically, in the SEM photograph, the area of each particle was measured, and the diameter of a circle having the same area was defined as the particle diameter of the particle. In the SEM photograph, 30 particles having the most universal size and shape were selected, the average primary particle size of the 30 particles was calculated, and the average value was defined as the average primary particle size (D) (nm).

Further, the average crystallite diameter of the vanadium dioxide-containing particles is characterized by being in the range of 1 to 15 nm, but is more preferably in the range of 1 to 10 nm.

「The“ crystallite ”according to the present invention refers to the largest region of a microcrystal present as a complete single crystal in polycrystalline particles.

FIG. 5 is a schematic view showing an example of the particle structure of the vanadium dioxide-containing particles according to the present invention.

As shown in FIG. 5, the vanadium dioxide-containing particles P according to the present invention are formed by a plurality of crystallites CL. By subjecting the slurry raw material liquid to a desalting treatment in advance, and changing the growth rate of the crystallite CL depending on the temperature and time during the hydrothermal reaction treatment, the average crystallite diameter of the vanadium oxide-containing particles is 1 It can be controlled within the range of １５15 nm. In addition, D shown in FIG. 5 is an average primary particle size of the vanadium dioxide-containing particles P.

Generally, the obtained average crystallite diameter A represents the size of the crystal growing in the same direction in the crystal grain. The small average crystallite diameter A means that the crystallite CL growing in a specific same direction in the crystal grain is small. Since the crystallite CL grows by applying the slurry raw material liquid that has been subjected to the desalting treatment in advance, crystal particles having an average crystallite diameter A larger than the average primary particle diameter D are formed.

平均 The average crystallite diameter A according to the present invention can be calculated by XRD (X-ray diffraction) measurement using the Scherrer formula shown in the following formula (1).

Equation (1)
A = Kλ / βcosθ
In the above equation (1), K is a Scherrer constant, and λ is an X-ray wavelength. β is the half value width of the diffraction line. θ is the Bragg angle for the diffraction line.

《Optical film》
The vanadium dioxide-containing particles according to the present invention can be preferably used for an optical film. The optical film referred to here has a transparent substrate and an optical functional layer formed on the transparent substrate, and the optical functional layer contains a resin and the vanadium dioxide (VO ₂ ) -containing particles according to the present invention. This is a film that exhibits thermochromic properties and has a configuration that:

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. Examples of the substrate include flexibility and production suitability (roll-to-roll suitability). From the viewpoint, a transparent resin film is preferable. The term “transparent” in the transparent substrate according to 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 is all.

において In the present invention, the thickness of the transparent substrate is preferably in the range of 30 to 200 μm, more preferably in the range of 30 to 100 μm, and still more preferably in the range of 35 to 70 μm. If the thickness of the transparent substrate is 30 μm or more, wrinkles and the like are less likely to occur during handling, and if the thickness is 200 μm or less, the glass curved surface when bonding to the glass substrate during production of laminated glass. Followability is improved.

In the present invention, the transparent substrate has a heat shrinkage within a range of 0.1 to 3.0% at a temperature of 150 ° C. from the viewpoint of preventing wrinkles of the optical film and cracking of the infrared reflective layer. Is more preferably in the range of 1.5 to 3.0%, and still more preferably 1.9 to 2.7%.

In the present invention, as described above, the transparent substrate applicable to the optical film is not particularly limited as long as it is transparent, and various transparent resin films can be used. For example, a polyolefin film (for example, , A polyethylene film, a polypropylene film, etc.), a polyester film (eg, a polyethylene terephthalate film, a polyethylene naphthalate film, etc.), a polyvinyl chloride film, a triacetyl cellulose film, etc., and preferably a polyester film, a triacetyl cellulose film. And more preferably a polyester film.

ポリエステル The polyester constituting the polyester film is not particularly limited, but is preferably a film-forming polyester having a dicarboxylic acid component and a diol component as main components. The main components of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylsulfondicarboxylic acid, diphenyletherdicarboxylic acid, diphenylethanedicarboxylic acid, Examples thereof include cyclohexanedicarboxylic acid, diphenyldicarboxylic acid, diphenylthioetherdicarboxylic acid, diphenylketonedicarboxylic acid, and phenylindanedicarboxylic acid. The diol component includes 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 polyesters containing these as main components, terephthalic acid or 2,6-naphthalenedicarboxylic acid as a dicarboxylic acid component, ethylene glycol or Polyesters containing 1,4-cyclohexanedimethanol as the main constituent are preferred. Among them, polyethylene terephthalate, polyethylene naphthalate, polyesters containing these as main constituents, copolymerized polyesters composed of terephthalic acid, 2,6-naphthalenedicarboxylic acid and ethylene glycol, and two or more of these polyesters Polyesters whose main constituent is a mixture are preferred.

特に The transparent resin film is particularly preferably a biaxially oriented polyester film, but a uniaxially stretched polyester film that has not been stretched or at least one stretched can also be used. Stretched films are preferred from the viewpoint of improving strength and suppressing thermal expansion. In particular, when the laminated glass provided with the optical film is used as a windshield of an automobile in the present invention, a stretched film is more preferable.

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

透明 The transparent resin film as the transparent substrate can be manufactured by a conventionally known general method. For example, a resin as a material was mixed with a solvent to prepare a dope, the dope was cast on a continuous support, a film was formed, and a partial rotation was performed on a continuously rotating endless support. Later, peeling off from the endless support, and then performing sufficient drying, and optionally performing a stretching treatment during or after drying, to produce an unstretched or stretched transparent resin film by a solution casting method. Can be. Further, for example, a resin as a material is melted by an extruder, extruded by an annular die or a T die, and quenched to produce a substantially amorphous, unoriented, unstretched transparent resin film. It can be produced by a drawing method.

Further, the transport direction of the transparent resin film (vertical direction) can be obtained by a known method such as uniaxial stretching, tenter-type sequential biaxial stretching, tenter-type simultaneous biaxial stretching, or tubular simultaneous biaxial stretching of the unstretched transparent resin film. , MD direction) or a transverse axis direction (width direction, TD direction) perpendicular to the transport direction of the transparent resin film, whereby a stretched transparent resin film can be produced. The stretching ratio in this case can be appropriately selected according to the resin used as the raw material of the transparent resin film, but it is preferable that the stretching is performed in the range of 2 to 10 times in the vertical axis direction and the horizontal axis direction. The stretching treatment may be further performed on a transparent resin film that has been stretched in advance.

The transparent resin film may be subjected to a relaxation treatment or an off-line heat treatment in view of dimensional stability. It is preferable that the relaxation treatment is performed, for example, in a step of stretching after heat setting in a polyester film stretching film-forming step, in a transverse stretching tenter, or in winding up after leaving the tenter. The relaxation treatment is preferably performed at a processing temperature of 80 to 200 ° C, and more preferably at a temperature of 100 to 180 ° C. It is preferable that the treatment is carried out at a relaxation rate in the range of 0.1 to 10% in both the transport direction and the horizontal axis direction, and it is more preferable that the treatment is carried out at a relaxation rate in the range of 2 to 6%. The substrate subjected to the relaxation treatment is subjected to off-line heat treatment so that the heat resistance is improved and the dimensional stability is further improved.

The undercoat layer coating liquid can be applied to one or both surfaces of the transparent resin film in-line during the film formation process. The resins used in the undercoat layer coating solution useful for transparent resin films include polyester resins, (meth) acrylic modified polyester resins, polyurethane resins, acrylic resins, vinyl resins, vinylidene chloride resins, polyethyleneimine vinylidene resins, and polyethylene. Examples include an imine resin, a polyvinyl alcohol resin, a modified polyvinyl alcohol resin, and gelatin, and any of them can be preferably used. Conventionally known additives can 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, spray coating and the like. The coating amount of the undercoat layer can be about 0.01 to 2 g / m ² (dry state).

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

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

The content of the vanadium dioxide-containing particles in the optical functional layer is preferably in the range of 1 to 60% by mass relative to the total mass of the optical functional layer, from the viewpoint of obtaining desired thermochromic properties, and 5 to 50% by mass. % Is more preferable.

従来 Conventionally known various additives can be used in the optical functional layer as long as the effects intended by the present invention are not impaired. Various additives that can be applied are listed below. For example, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, JP-A-62-261476, etc., JP-A-57-74192, JP-A-57-74192, Discoloration inhibitors, anions described in JP-A-87989, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091 and JP-A-3-13376. , Cationic or nonionic surfactants, JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, and JP-A-Hei. Fluorescent brightening agents described in JP-A-219266, pH adjusting agents such as sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide and potassium carbonate, defoaming , Diethylene glycol and other lubricants, preservatives, fungicides, antistatic agents, matting agents, heat stabilizers, antioxidants, flame retardants, crystal nucleating agents, inorganic particles, organic particles, thickeners, lubricants, infrared absorption And various known additives such as agents, dyes, and pigments.

The method for producing the optical film (the method for forming the optical functional layer) is not particularly limited, and can be applied in the same manner as a known method, or appropriately modified, except for using the vanadium dioxide-containing particles according to the present invention. . Specifically, a method of preparing a coating solution containing vanadium dioxide-containing particles, coating the coating solution on a transparent substrate by a wet coating method, and drying to form an optical functional layer is preferable.

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

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. Unless otherwise specified, “%” and “parts” mean “% by mass” and “parts by mass”, respectively. In the description of each drawing, the numbers described after the constituent requirements represent the reference numerals described in each drawing.

<< Preparation of particles containing vanadium dioxide >>
[Preparation of vanadium dioxide-containing particles 101]
(Preparation of slurry raw material liquid A)
19.0 g of vanadium (IV) oxide (VOSO ₄ ) was dissolved in ion-exchanged water to 300 mL as the raw material liquid 1, and 68 mL of an aqueous 3.0 mol / L NH ₃ solution was added as an alkali while stirring this liquid. Thus, a slurry raw material liquid A was prepared.

(Desalination of slurry raw material liquid A)
Next, the slurry raw material liquid A containing vanadium (IV) oxide sulfate and alkali was subjected to desalting treatment 1 by the following centrifugation method to prepare a desalted slurry raw material liquid 1.

<Desalination 1>
Using a known centrifugal separator, a solid-liquid separation is performed by centrifugation at 30 ° C. on the slurry raw material liquid A containing vanadium (IV) oxide sulfate and alkali, and then a part of the aqueous separation liquid is removed from the system. Then, the same volume of ion-exchanged water as that discharged was added, and then the dispersion treatment was performed. This operation was repeated to discharge unnecessary salts, and the electric conductivity of the slurry raw material liquid was set to 1 mS / m and pH were adjusted to 7.5 using a 3.0 mol / L aqueous NH ₃ solution to prepare a desalted slurry raw material liquid 1.

(Hydrothermal reaction treatment)
Next, with respect to the slurry raw material liquid 1 subjected to the desalting treatment, vanadium dioxide-containing particles 101 were prepared according to the following method using a flow-type reaction apparatus having a hydrothermal reaction section shown in FIGS.

The slurry raw material container 5 shown in FIGS. 3 and 4 contains vanadium (IV) oxide desalted by the above-described method and an alkali as the raw material liquid 1 and has an electric conductivity (mS / m) of 1 mS. / M and a slurry raw material liquid 1 having a pH of 7.5 were stored. On the other hand, ion-exchanged water was stored as the raw material liquid 2 in the ion-exchanged water container 2 shown in FIGS.

The desalted slurry raw material liquid 1 containing vanadium (IV) oxide sulfate and alkali is sent from the slurry raw material liquid container 5 to the inside of the flow path 6 by the pump 7, and is heated by the heating medium 15 at 25 ° C. and 30 MPa. Pressure was applied to meet the conditions.

On the other hand, the ion-exchanged water, which is the raw material liquid 2, is degassed and then sent from the ion-exchanged water container 2 to the inside of the flow path 3 by the pump 4, and heated with the heating medium 13 at 440 ° C. and 30 MPa. Press to obtain supercritical water.

Next, at the confluence point MP shown in FIGS. 3 and 4, the slurry raw material liquid 1 containing vanadium (IV) oxide sulfate and the alkali, and the ion exchange water as supercritical water were used as a volume ratio of the slurry raw material liquid 1: ion The mixture was mixed under the condition of exchanged water = 1: 4 to form a reaction solution, and the reaction solution was sent to the hydrothermal reaction section 16 as a hydrothermal reaction section while maintaining the supercritical state. In the hydrothermal reaction section, the liquid was sent to the heating section piping 17 arranged in the heating medium 14. The hydrothermal reaction conditions in the heating pipe section 17 were performed at 440 ° C. and 30 MPa, and the treatment time (passing time) was set to 5 seconds, to form particles 101 containing vanadium dioxide (VO ₂ ). Next, the reaction liquid was cooled in the cooling unit 8 to prepare the dispersion liquid 1 containing the vanadium dioxide-containing particles 101 and water.

[Preparation of vanadium dioxide-containing particles 102]
In the preparation of the above-mentioned particles 101 containing vanadium dioxide, instead of the slurry raw material liquid 1 prepared by subjecting to desalination treatment 1 by a centrifugal separation method, a slurry raw material liquid prepared by carrying out desalination treatment 2 by the following ultrafiltration method In the same manner except that No.2 was used, vanadium dioxide-containing particles 102 were prepared.

(Preparation of desalted slurry raw material liquid 2)
<Desalination 2>
The slurry raw material liquid A containing vanadium (IV) oxide sulfate and alkali at 30 ° C. was subjected to desalination treatment 2 by ultrafiltration using the ultrafiltration apparatus 50 shown in FIG. A slurry raw material liquid 2 was prepared.

The slurry raw material liquid A (52, initial electric conductivity: 3400 mS / m) having a liquid temperature of 30 ° C. is stored in the adjusting pot 51, and is circulated using the circulation pump 54. The water containing salt in the raw material A1 is discharged at a discharge amount V1 from a discharge port 56, and then from a stock tank 57 of ion-exchanged water 58 whose pH has been adjusted to 10.0 by adding ammonia via a supply line 59. Thus, ion-exchanged water 58 having the same volume as the discharged amount V1 in the ultrafiltration unit 55 and having a pH of 10 was added in an added amount V2. This operation is repeated while measuring the electric conductivity (mS / m) of the desalted slurry raw material liquid 52 with the electric conductivity meter 60, and the electric conductivity (mS / m) of the slurry raw material liquid 52 at 25 ° C. At the time of reaching 3000 mS / m, the desalting operation was terminated, and then the dispersion treatment was performed to prepare the slurry raw material liquid 2 after the desalination treatment. At this time, the pH of the desalted slurry raw material liquid 2 measured at 25 ° C. was 10.2.

[Preparation of vanadium dioxide-containing particles 103]
In the preparation of the vanadium dioxide-containing particles 102, vanadium dioxide-containing particles 103 were prepared in the same manner as the hydrothermal reactor, except that the following autoclave was used instead of a flow-type reactor having a hydrothermal reactor. .

(Hydrothermal reaction treatment: autoclave)
The desalted slurry raw material liquid 2 (electric conductivity: 3000 mS / m, pH: 10.2) is placed in an autoclave having an internal volume of 500 mL, and subjected to a hydrothermal reaction treatment at 300 ° C. and 8.6 MPa for 6 hours. Thus, vanadium dioxide-containing particles 103 were formed. Next, the reaction liquid was cooled to prepare a dispersion liquid containing the vanadium dioxide-containing particles 103.

[Preparation of vanadium dioxide-containing particles 104]
In the preparation of the vanadium dioxide-containing particles 102, the desalination treatment conditions were appropriately changed by ultrafiltration using a slurry raw material liquid A at 30 ° C. instead of the desalted slurry raw material liquid 2, and A slurry raw material liquid 3 having a conductivity of 100 mS / m and a pH of 8.0 (desalting treatment 3) was prepared, and vanadium dioxide-containing particles 104 were prepared in the same manner except that this was used.

[Preparation of vanadium dioxide-containing particles 105]
In the preparation of the above-mentioned vanadium dioxide-containing particles 102, the desalination treatment conditions were appropriately changed by an ultrafiltration method using a slurry raw material liquid A at 30 ° C. instead of the desalted slurry raw material liquid 2, and the electric conductivity was changed. A slurry raw material liquid 4 (desalting treatment 4) having a rate of 620 mS / m and a pH of 9.2 was prepared, and vanadium dioxide-containing particles 105 were prepared in the same manner except that this was used.

[Preparation of vanadium dioxide-containing particles 106]
In the preparation of the vanadium dioxide-containing particles 102, the desalination treatment conditions were appropriately changed by ultrafiltration using a slurry raw material liquid A at 30 ° C. instead of the desalted slurry raw material liquid 2, and A slurry raw material liquid 5 having a conductivity of 1000 mS / m and a pH of 10.7 (desalting treatment 5) was prepared, and vanadium dioxide-containing particles 106 were prepared in the same manner except that this was used.

[Preparation of vanadium dioxide-containing particles 107]
In the preparation of the above-mentioned particles 101 containing vanadium dioxide, the conditions of the desalting treatment were appropriately changed by a centrifugal separation method using a slurry raw material liquid A at 30 ° C. instead of the desalted slurry raw material liquid 1 to obtain an electric conduction. A slurry raw material liquid 6 (desalting treatment 6) having a rate of 620 mS / m and a pH of 8.0 was prepared, and vanadium dioxide-containing particles 107 were prepared in the same manner except that this was used.

(Preparation of vanadium dioxide-containing particles 108)
In the preparation of the above-mentioned particles 107 containing vanadium dioxide, a slurry raw material liquid 6 having a conductivity of 620 mS / m and a pH of 8.0 (desalting treatment 6) was used. 195 ° C., the reaction pressure was 10 MPa, and the treatment time was 2 seconds, except that the vanadium dioxide-containing particles 108 were prepared in the same manner.

[Preparation of vanadium dioxide-containing particles 109]
In the preparation of the above-mentioned particles 107 containing vanadium dioxide, a slurry raw material liquid 6 (desalting treatment 6) having an electric conductivity of 620 mS / m and a pH of 8.0 was used. Was changed to 2 seconds to prepare vanadium dioxide-containing particles 109 in the same manner.

[Preparation of vanadium dioxide-containing particles 110]
In the preparation of the above-mentioned vanadium dioxide-containing particles 102, the desalination treatment conditions were appropriately changed by an ultrafiltration method using a slurry raw material liquid A at 30 ° C. instead of the desalted slurry raw material liquid 2, and the electric conductivity was changed. A slurry raw material liquid 7 having a rate of 200 mS / m and a pH of 11.8 (desalting treatment 7) was prepared, and vanadium dioxide-containing particles 110 were prepared in the same manner except that this was used.

[Preparation of vanadium dioxide-containing particles 111]
In the preparation of the above-mentioned vanadium dioxide-containing particles 104, the electric conduction was performed by appropriately changing the desalting treatment conditions by an ultrafiltration method using a slurry raw material liquid A at 30 ° C. instead of the desalted slurry raw material liquid 3. A slurry raw material liquid 8 (desalting treatment 8) having a rate of 100 mS / m and a pH of 5.5 was prepared, and vanadium dioxide-containing particles 111 were prepared in the same manner except that this was used.

[Preparation of vanadium dioxide-containing particles 112]
In preparing the vanadium dioxide-containing particles 105, a slurry having an electric conductivity of 620 mS / m and a pH of 8.0 was prepared in the same manner except that the treatment temperature during the ultrafiltration of the slurry raw material liquid A was changed to 50 ° C. Preparation of vanadium dioxide-containing particles 112 was prepared in the same manner except that the raw material liquid 9 (desalting treatment 9) was used.

[Preparation of vanadium dioxide-containing particles 113]
In the preparation of the vanadium dioxide-containing particles 105, the slurry raw material liquid A was changed to the following slurry raw material liquid B, and the desalting treatment conditions were appropriately changed to obtain a slurry having an electric conductivity of 620 mS / m and a pH of 8.0. A raw material liquid 10 (desalting treatment 10) was prepared, and vanadium dioxide-containing particles 113 were prepared in the same manner except that this was used.

(Preparation of slurry raw material liquid B)
As a raw material liquid 1, 19.0 g of vanadium (IV) oxide (VOSO ₄ ) was dissolved in ion-exchanged water to 300 mL, and while stirring this liquid, 68 mL of a 3.0 mol / L NaOH aqueous solution was added as an alkali while stirring. And a slurry raw material liquid B was prepared.

[Preparation of vanadium dioxide-containing particles 114]
In the preparation of the vanadium dioxide-containing particles 105, the pH during ultrafiltration of the slurry raw material liquid A was changed to 8.0, and the hydrothermal reaction conditions in the flow-type reactor were changed to a reaction temperature of 380 ° C., and a treatment time of At 10 seconds, vanadium dioxide-containing particles 114 were prepared in the same manner, except that each was changed.

[Preparation of vanadium dioxide-containing particles 115]
In the preparation of the vanadium dioxide-containing particles 105, the pH during ultrafiltration of the slurry raw material liquid A was changed to 8.0, and the reaction temperature was changed to 380 ° C. as hydrothermal reaction conditions in a flow reactor. Prepared vanadium dioxide-containing particles 115 in the same manner.

[Preparation of vanadium dioxide-containing particles 116]
In the preparation of the vanadium dioxide-containing particles 106, the hydrothermal reaction conditions in a flow-type reactor were the same except that the reaction temperature was changed to 390 ° C., the reaction pressure was changed to 28.0 MPa, and the treatment time was changed to 60 seconds. Vanadium dioxide-containing particles 116 were prepared.

[Preparation of vanadium dioxide-containing particles 117]
In the preparation of the vanadium dioxide-containing particles 106, the hydrothermal reaction conditions in the flow-type reactor, the reaction temperature was 410 ° C., the reaction pressure was 35.0 MPa, and the treatment time was 10 seconds. Vanadium dioxide-containing particles 117 were prepared.

詳細 The details of each vanadium dioxide-containing particle prepared as described above are shown in Table I.

<< Preparation of optical film >>
[Preparation of Optical Film 101]
On a polyethylene terephthalate film having a thickness of 50 μm (A4300 manufactured by Toyobo, with a double-sided easy-adhesion layer), a coating liquid 1 for forming an optical functional layer having the following composition was dried with a die coater to a dry film thickness of 2.0 μm. The wet coating was performed by adjusting the coating amount, and the coating was dried at 90 ° C. for 1 minute to produce an optical film 101 as a thermochromic film.

<Preparation of coating liquid 1 for forming optical functional layer>
9.3 parts by mass (solid content) of dispersion containing vanadium dioxide-containing particles 101
Resin binder: (poly-N-vinylacetamide, trade name: GE191-103, manufactured by Showa Denko KK, molecular weight 900000) 90.7 parts by mass The above-mentioned constituent materials are sequentially added, mixed and dissolved, and the solid content concentration is 3 The mixture was diluted with water so as to have a concentration of 0.0% by mass to prepare a water-based coating liquid 1 for forming an optical functional layer.

[Production of optical films 102 to 117]
In the production of the optical film 101, the optical films 102 to 117 were prepared in the same manner except that the vanadium dioxide-containing particles 101 used in the preparation of the optical functional layer forming coating liquid 1 were changed to vanadium dioxide-containing particles 102 to 117, respectively. Was prepared.

<< Evaluation of vanadium dioxide-containing particles and optical films >>
(Evaluation of vanadium dioxide-containing particles)
Each of the vanadium dioxide-containing particles prepared above was evaluated as follows.

(Measurement of average crystallite diameter)
With respect to each vanadium dioxide-containing particle, the crystallite diameter of 30 particles was measured using a powder X-ray diffractometer (manufactured by Rigaku, MiniFlex II), and the average value was determined. CuKα rays were used as the X-ray source, and the average crystallite diameter was calculated by the Scherrer equation of the following equation (1) using the main peak ((011) plane) of X-ray diffraction.

Equation (1)
D = Kλ / βcosθ
In the above equation (1), K is a Scherrer constant, and λ is an X-ray wavelength. β is the half value width of the diffraction line. θ is the Bragg angle for the diffraction line.

Next, the average crystallite diameters measured above were classified according to the following ranks.

〇: Average crystallite size is 1 nm or more and 15 nm or less ×: Average crystallite size exceeds 15 nm (measurement of average primary particle size)
The dispersion containing each of the vanadium dioxide-containing particles and water prepared above was dried and solidified in an oven at 120 ° C. to obtain a powder, and a particle sample for measurement was prepared.

Next, using the obtained particle sample, an SEM photograph was taken with a scanning electron microscope (Hitachi S-5000, manufactured by Hitachi, Ltd.). The particle diameter was calculated using the taken SEM photograph (1100 nm × 950 nm). The particle diameter of the vanadium dioxide-containing particles, the area circle equivalent diameter is applied, the area of each vanadium dioxide-containing particle is measured in the SEM photograph, and the diameter of the circle having the same area is determined as the particle diameter of the vanadium dioxide-containing particles. did. In the SEM photograph, 30 particles having the most universal dimensions and shapes were selected, the average primary particle size of the 30 particles was calculated, and the average value was defined as the average primary particle size D (nm).

Next, the average primary particle size measured above was classified according to the following rank.

◎: Average primary particle size is 1 nm or more and 20 nm or less ：: Average primary particle size is more than 20 nm and 30 nm or less Δ: Average primary particle size is more than 30 nm and 40 nm or less ×: Average primary particle size is , 40 nm.

(Evaluation of optical film)
(Evaluation of haze)
The haze (%) of each of the optical films prepared above was measured at room temperature using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH2000), and the haze was evaluated according to the following criteria.

◎: Haze is less than 1.5% ：: Haze is 1.5% or more and less than 2.0% Δ: Haze is 2.0% or more and less than 3.0% ×: Haze is 3.0% or more.

(Evaluation of heat insulation (Evaluation of ΔTSER))
For each of the optical films produced above, the thermal barrier property (TSER) difference (ΔTSER), which is a measure of thermochromic properties, was evaluated.

Specifically, using a spectrophotometer (using an integrating sphere, U-4000, manufactured by Hitachi, Ltd.), the light transmittance and light reflectance of every 2 nm in the wavelength region of 300 to 2500 nm are measured for each optical film. The temperature was measured at low temperature (10 ° C.) and high temperature (80 ° C.).

Next, the solar reflectance R (DS) and the solar transmittance T (DS) are determined according to the method described in JIS {R} 3106: 1998, and then the heat shield at low and high temperatures calculated from the following equation (2). The performance (TSER,%) was obtained, and then ΔTSER (%) was calculated according to the equation (3), and the heat shielding property was evaluated according to the following evaluation criteria.

Equation (2)
TSER (%) = ((100−T (DS) −R (DS)) × 0.7143) + R (DS)
Equation (3)
ΔTSER (%) = TSER (high temperature)-TSER (low temperature)
：: ΔTSER is 13.0% or more Δ: ΔTSER is 8.0% or more and less than 13.0% X: ΔTSER is less than 8.0%.

The results obtained above are shown in Table II.

As is clear from the results shown in Table II, before the hydrothermal reaction, the slurry raw material liquid containing the vanadium-containing compound was subjected to a desalting treatment, and the pH of the slurry raw material liquid at 25 ° C. was adjusted to 8.0 to 11.0. After the electric conductivity at 25 ° C. is in the range of 10 to 1000 mS / m, the particles are treated by a hydrothermal synthesis method so that the average primary particle diameter of the vanadium dioxide-containing particles is in the range of 1 to 30 nm. The optical film to which the vanadium dioxide-containing particles are applied can achieve both excellent thermochromic properties (ΔTSER) and transparency (haze resistance). I was able to confirm that I could.

The vanadium dioxide-containing particles produced by the method for producing vanadium dioxide-containing particles of the present invention have a small average particle size, a low haze, excellent thermochromic properties, and a property between an internal environment such as a room or a vehicle and an external environment. In places where large heat exchange occurs, for example, architectural window glass and vehicle body window glass, it can be suitably used as an optical film or the like that can achieve both energy saving and comfortableness.

DESCRIPTION OF SYMBOLS 1 Flow-type reaction apparatus 2 Ion

exchange water container

3, 6, 11, 18 Flow path (piping)
4, 7, 12 Pump 5 Slurry raw material liquid container 8

Cooling unit

9, 10

Tank

13, 14, 15 Heating medium 16 Hydrothermal reaction unit 17 Heating unit piping 19 Control valve C Cooling medium IN Heating medium inlet OUT Heating medium outlet L Line length of heating section piping MP Junction point TC Temperature sensor 50 Ultrafiltration device 51 Regulating pot 52 Slurry raw material liquid 53 Pipe 54 Circulation pump 55 Ultrafiltration section 56 Discharge port 57 Replenishing pH adjusting water stock pot 58 Refilling pH Adjustment water 59 Replenishment pH adjustment water supply line 60 Electrical conductivity meter 61 pH meter V1 Emission V2 Replenishment pH adjustment water addition amount A Average crystallite size CL Crystallite D Particle size P Vanadium dioxide-containing particles

Claims

A method for producing vanadium dioxide-containing particles using a flow reactor having a hydrothermal reaction section,
It has at least the following first to third steps:
First step: a step of preparing a slurry raw material liquid containing at least a vanadium-containing compound, a reaction modifier, and water Second step: a step of subjecting the slurry raw material liquid to a desalting treatment Third step: applying the desalting treatment A step of producing vanadium dioxide-containing particles by a hydrothermal reaction method using a reaction liquid obtained by mixing a slurry raw material liquid and water in a supercritical or subcritical state. In the second step, the pH of the slurry raw material liquid at 25 ° C. Within the range of 8.0 to 11.0,
Maintaining the electrical conductivity at 25 ° C. within the range of 10 to 1000 mS / m;
The average primary particle diameter of the vanadium dioxide-containing particles is in the range of 1 to 30 nm, and
A method for producing vanadium dioxide-containing particles, wherein the particles are produced by adjusting the average crystallite diameter to fall within a range of 1 to 15 nm.
The method for producing vanadium dioxide-containing particles according to claim 1, wherein the desalting treatment for removing salts from the slurry raw material liquid is performed using an ultrafiltration device.
3. The method for producing vanadium dioxide-containing particles according to claim 1, wherein the desalting treatment for removing salts from the slurry raw material liquid is performed at a liquid temperature of 30 ° C. or lower.
水 The method for producing vanadium dioxide-containing particles according to any one of claims 1 to 3, wherein water constituting the reaction solution in the third step is water in a supercritical state.