JP2017181996A - Chromic sheet and method for producing chromic sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chromic sheet having flexibility and high durability, and to provide a method for producing the same.SOLUTION: A chromic sheet 10 has any one structure of (1) a structure in which a chromic layer 14 containing a chromic oxide is laminated on a surface of a base material 12 containing an organic material having a siloxane skeleton, (2) a structure in which particles containing a chromic oxide are dispersed in a base material containing an organic material having a siloxane skeleton and (3) a structure in which a chromic layer where particles containing a chromic oxide are dispersed in an organic material having a siloxane skeleton is laminated on a surface of a resin base material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a chromic sheet and a method for producing a chromic sheet.

In recent years, household fuel cells and fuel cell vehicles that generate electricity using hydrogen as a raw material as clean energy have been put into practical use. However, since hydrogen gas is colorless and transparent and odorless and has a high combustion rate, it may explode if it leaks into the atmosphere.
As means for detecting leakage of hydrogen gas, hydrogen gas sensors such as a catalytic combustion type and a semiconductor type are known. However, these hydrogen gas sensors require heating of the element and are a mechanism for detecting hydrogen gas by a change in electric resistance. Therefore, there is a possibility that explosion occurs when a gas mixed with hydrogen and oxygen touches. In addition, since these hydrogen gas sensors require a power source for detection, they cannot be used at the time of a power failure, and furthermore, since the shape of the element is fixed, for example, to detect leakage from a gas pipe, It is necessary to arrange a large number of sensors along the pipe, and it is difficult to identify the leaked portion.

  On the other hand, research using chromic materials having the property of reversibly changing color by external stimuli such as light, electricity, gas, heat (photochromism, electrochromism, gas chromism, thermochromism, etc.) has been conducted. ing. As the chromic material, for example, tungsten oxide, molybdenum oxide, niobium oxide, and the like are known, and application to optical elements, light control members, color displays, gas sensors, and the like has been proposed.

  When manufacturing a member using a chromic material, it is usually manufactured by attaching particles containing a chromic material to the surface of a glass substrate or dispersing the particles in the glass substrate. However, the glass substrate is excellent in heat resistance, light transmittance, etc., but it is poor in flexibility, and it is difficult to apply it to a bent portion such as a gas pipe.

As a chromic film having flexibility, for example, a photochromic film in which molybdenum (Mo) is doped into a composite film formed by blending tungsten oxide (WO ₃ ) with a transparent urethane resin is known (for example, non-patent literature). 1).

Journal of Ceramic Society of Japan 12 [1] 106-108 2013

  Since the photochromic film disclosed in Non-Patent Document 1 has flexibility, for example, it can be considered that tungsten oxide and platinum are mixed and used as a gas sensor at a bent portion of a gas pipe or the like. However, since tungsten oxide has a photocatalytic action, the urethane resin used as a base material deteriorates early in places exposed to sunlight such as outdoors, and cannot withstand long-term use.

  An object of this invention is to provide the chromic sheet which has a softness | flexibility and has high durability, and its manufacturing method.

Specific means for achieving the above object are as follows.
<1> (1) Configuration in which a chromic layer containing a chromic oxide is laminated on the surface of a base material containing an organic material having a siloxane skeleton,
(2) A structure in which particles containing a chromic oxide are dispersed in a substrate containing an organic material having a siloxane skeleton, or (3) a chromic oxide in an organic material having a siloxane skeleton on the surface of a resin substrate. The chromic sheet | seat which has the structure by which the chromic layer in which the particle | grains containing are disperse | distributed is laminated | stacked.
<2> The chromic sheet according to <1>, wherein the organic material having a siloxane skeleton is dimethylpolysiloxane.
<3> The chromic according to <1> or <2>, wherein the chromic oxide is an oxide containing at least one metal atom selected from the group consisting of tungsten, vanadium, niobium, tantalum, zirconium, and chromium. Sheet.
<4> The chromic sheet according to any one of <1> to <3>, wherein the particles containing the chromic oxide are particles containing tungsten oxide and platinum.
<5> The chromic sheet according to any one of <1> to <4>, which is for a gas sensor or for dimming.

<6> a step of hydrophilizing at least one surface of a substrate containing an organic material having a siloxane skeleton;
Forming a chromic layer containing the chromic oxide on the substrate by applying and drying a precursor liquid containing a chromic oxide precursor on the hydrophilic-treated surface of the substrate;
A method for producing a chromic sheet having
<7> The step of hydrophilizing the step of bringing a treatment liquid containing hydrogen peroxide into contact with at least one surface of the substrate, or N- (2-hydroxyethyl) on at least one surface of the substrate. ) The method for producing a chromic sheet according to <6>, including a step of graft polymerization of acrylamide.

<8> a step of preparing an uncured organic material having a siloxane skeleton, particles containing a chromic oxide and a solvent, and preparing a dispersion in which the particles containing the chromic oxide are dispersed;
The chromic oxide is contained in the base material containing the organic material having the siloxane skeleton by adding a curing agent for curing the uncured organic material having the siloxane skeleton to the dispersion and forming the sheet into a sheet shape. Forming a chromic sheet in which particles are dispersed;
A method for producing a chromic sheet having
<9> The method for producing a chromic sheet according to <8>, wherein the solvent is tert-butanol.

<10> The method for producing a chromic sheet according to any one of <6> to <9>, wherein the organic material having a siloxane skeleton is dimethylpolysiloxane.
<11> The particles containing the chromic oxide are oxide particles containing at least one metal atom selected from the group consisting of tungsten, vanadium, niobium, tantalum, zirconium, and chromium. <6> to <10> The manufacturing method of the chromic sheet as described in any one of these.
<12> The method for producing a chromic sheet according to any one of <6> to <11>, wherein the particles containing the chromic oxide are particles containing tungsten oxide and platinum.

  According to the present invention, it is possible to provide a chromic sheet having flexibility and high durability and a method for manufacturing the same.

It is the schematic which shows an example of a structure of the chromic sheet which concerns on 1st Embodiment. It is the schematic which shows an example of a structure of the chromic sheet which concerns on 2nd Embodiment. It is a flowchart which shows an example (Example 1) of the manufacturing method of the chromic sheet which concerns on 1st Embodiment. Is a diagram showing the change before and after the color placing electrochromic sheet having a chromic layer comprising TiO ₂ and WO ₃ prepared in Example 1 in a 100% hydrogen gas. It is a figure which shows the change of the light absorbency (wavelength 800nm) at the time of putting in the atmosphere, after putting in the gas containing 1% of hydrogen before and after heat-processing the chromic sheet | seat manufactured in Example 1 at 250 degreeC. Is a diagram showing the change before and after the color for irradiating ultraviolet light (254 nm) in the electrochromic sheet having a chromic layer comprising TiO ₂ and WO ₃ prepared in Example 2. It is a figure which shows the change of the light transmittance before and behind irradiating the chromic sheet | seat manufactured in Example 2 with ultraviolet light (254 nm). It is a flowchart which shows the other example (Example 3) of the manufacturing method of the chromic sheet which concerns on 1st Embodiment. It is a figure which shows the state deform | transformed after discoloring the chromic sheet | seat manufactured in Example 3 with hydrogen gas. It is a flowchart which shows an example (Example 4) of the manufacturing method of the chromic sheet which concerns on 2nd Embodiment. It is a figure which shows the measurement result by X-ray diffraction (XRD) about the powder manufactured in Example 4. FIG. It is a figure which shows the observation image by a field emission type | mold scanning electron microscope (FE-SEM) about the powder manufactured in Example 4. FIG. It is a figure which shows the change of the color before and behind exposing the chromic sheet | seat manufactured in Example 4 to 100% hydrogen atmosphere. It is a figure which shows the change of the light transmittance before and after exposing the chromic sheet | seat manufactured in Example 4 to 100% hydrogen atmosphere. It is a figure which shows the change (memory performance) of the light transmittance (wavelength 800nm) after exposing the chromic sheet manufactured in Example 4 to 100% hydrogen atmosphere, and putting in air | atmosphere. A chromic glass substrate (Comparative Example 1) in which a dispersion containing Pt / WO ₃ particles is coated on a glass substrate to form a chromic layer is exposed to 100% hydrogen atmosphere, and then light transmittance after being placed in the atmosphere ( It is a figure which shows the change (memory performance) of wavelength 800nm.

Hereinafter, a chromic sheet according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. Note that reference numerals in the drawings may be omitted.
In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value, and the unit is only in the upper limit of the numerical range. When attached, it means the same unit throughout the numerical range.
In addition, in this specification, the term “process” is not limited to an independent process, and may be used when the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. include.

As a result of repeated research on chromic sheets having both flexibility and durability, the present inventors use an organic material having a siloxane skeleton such as dimethylpolysiloxane as a base material, and include a chromic oxide on the base material. It has been conceived that a chromic sheet having not only flexibility but also high durability can be obtained if a chromic layer is laminated or particles containing a chromic oxide can be dispersed in a substrate.
However, organic materials having a siloxane skeleton have poor compatibility or affinity with chromic oxides such as tungsten oxide. For example, dimethylpolysiloxane is used as a base material and a dispersion of particles containing the chromic oxide is applied onto the base material. Thus, it is difficult to form a chromic layer. For example, even if particles containing dimethylpolysiloxane and a chromic oxide are mixed and formed into a sheet shape, the particles containing the chromic oxide are aggregated and the particles containing the chromic oxide are hardly dispersed throughout the sheet.

Therefore, the present inventors have further researched, on a base material using an organic material having a siloxane skeleton by applying a specific treatment to the material constituting the chromic sheet to improve compatibility or affinity. It was found that a chromic layer with high adhesion can be formed, or particles containing a chromic oxide can be dispersed throughout the substrate.
Furthermore, the present inventors formed a chromic layer in which chromic oxide particles are dispersed in an organic material having a siloxane skeleton on the substrate even when a substrate using a resin other than an organic material having a siloxane skeleton is used. Thus, a chromic sheet having flexibility and high durability and capable of exhibiting high chromic performance over a long period of time has been found.

That is, the chromic sheet according to the embodiment of the present invention includes (1) a configuration in which a chromic layer containing a chromic oxide is laminated on a surface of a substrate containing an organic material having a siloxane skeleton, and (2) a siloxane skeleton. A structure in which particles containing a chromic oxide are dispersed in a base material containing an organic material, or (3) particles containing a chromic oxide are dispersed in an organic material having a siloxane skeleton on the surface of a resin base material. The chromic layers are stacked.
Hereinafter, the chromic sheet having the configuration (1), (2), or (3) will be specifically described as the first embodiment, the second embodiment, or the third embodiment, respectively.

The organic material having a siloxane skeleton and the chromic oxide may be selected according to the application of the chromic sheet, but in each embodiment described below, dimethylpolysiloxane (hereinafter referred to as “an organic material having a siloxane skeleton”) is used. In the first and third embodiments, as a chromic layer containing a chromic oxide, tungsten oxide that is a chromic oxide and platinum that serves as a catalyst for dissociating hydrogen molecules are used in the first and third embodiments. In the second embodiment, a chromic particle including platinum (Pt) and tungsten oxide (hereinafter referred to as “Pt / WO ₃ particle”) is provided as a chromic oxide-containing particle. The material constituting the chromic sheet of the present invention is mainly described below. It is not limited to it.
Moreover, although the case where the chromic sheet | seat which concerns on this embodiment is mainly used as a sheet | seat for hydrogen gas sensors or a light control sheet is demonstrated in the following description, the use of the chromic sheet | seat of this invention is not limited to these.

<Chromic sheet according to the first embodiment>
FIG. 1 shows an example of the configuration of the chromic sheet according to the first embodiment. The chromic sheet 10 according to the first embodiment includes a chromic layer 14 containing a chromic oxide on the surface of a base material 12 containing an organic material having a siloxane skeleton (hereinafter sometimes simply referred to as “base material”). It has a laminated structure.

(Substrate containing an organic material having a siloxane skeleton)
The chromic sheet according to the first embodiment includes a substrate 12 containing an organic material having a siloxane skeleton (SiO). A base material including an organic material having a siloxane skeleton has flexibility and can be placed in close contact with an object having a curved surface such as a gas pipe. Therefore, the chromic sheet according to this embodiment can be easily attached to and detached from a curved surface such as a gas pipe or an uneven surface.
In addition, the organic material having a siloxane skeleton contained in the base material used in the first embodiment has a property that does not easily deteriorate. Therefore, even if the chromic oxide contained in the chromic layer has a photocatalytic function, the base material is hardly deteriorated and the chromic layer is prevented from being peeled off.

  The base material containing an organic material having a siloxane skeleton includes a homopolymer of a monomer having a siloxane skeleton, a copolymer of a plurality of types of monomers having a siloxane skeleton, a monomer having a siloxane skeleton, and a monomer having no siloxane skeleton. For example, dimethylpolysiloxane, methylphenylpolysiloxane, modified products thereof (for example, amino-modified, alkyl-modified, etc.) and derivatives thereof can be used.

In particular, since dimethylpolysiloxane is excellent in gas permeability, it is suitable as a material constituting the substrate when the chromic sheet according to this embodiment is used as a gas sensor.
In addition, dimethylpolysiloxane has high transparency (light transmittance) in the wavelength range of 200 to 1100 nm, and is difficult to yellow due to deterioration over time. Therefore, dimethylpolysiloxane is suitable as a material constituting the substrate even when the chromic sheet according to the present embodiment is used as a light control sheet whose color changes by light irradiation.
Furthermore, since dimethylpolysiloxane has high heat resistance and can be heated to about 250 ° C., it is difficult to be deformed even if heat treatment is performed when forming a chromic layer on a substrate.

The base material used in the first embodiment is configured to include an organic material having a siloxane skeleton. However, unless the chromic layer can be formed on the base material and the effects of the present invention are not significantly impaired, siloxane is used. Materials (additives) other than the organic material having a skeleton may be included.
For example, an ultraviolet absorber etc. are mentioned.

  The thickness of the base material containing the organic material having a siloxane skeleton is not particularly limited, and may be selected according to the application. For example, when the chromic sheet according to the present embodiment is disposed as a gas sensor in a portion having a curved surface such as a gas pipe, the thickness of the base material is preferably about 50 μm to 5 mm from the viewpoint of flexibility.

  As a base material containing an organic material having a siloxane skeleton, a commercially available product may be used, for example, Tokawa Rubber's silicone rubber sheet K-125.

(Chromic layer)
In the chromic sheet according to the first embodiment, the chromic layer 14 containing a chromic oxide is laminated on the surface of the substrate 12 containing an organic material having a siloxane skeleton.

  As the chromic oxide contained in the chromic layer, a known chromic oxide having a property of being reversibly discolored by an external stimulus such as light or gas can be used. For example, an oxide containing at least one metal atom selected from the group consisting of tungsten, vanadium, niobium, tantalum, zirconium, and chromium can be given.

For example, in tungsten oxide, electrons generated when hydrogen gas (hydrogen molecule) is dissociated into hydrogen ions by platinum or the like reduces W ⁶⁺ to W ⁵⁺ , so that the color tone of tungsten oxide changes to blue. Therefore, when the chromic layer contains tungsten oxide and platinum, tungsten oxide exhibits a gas chromic function.
On the other hand, a base material containing an organic material having a siloxane skeleton has high gas permeability. For example, even if the base side is brought into contact with the gas pipe, the gas leaked from the gas pipe permeates the base material and is absorbed by the chromic layer. Can be discolored.
Therefore, the chromic sheet according to the present embodiment can be suitably used as a gas sensor sheet by sticking around a gas pipe through which hydrogen gas circulates or a pipe seal.

Tungsten oxide exhibits a photochromic function in which, when irradiated with ultraviolet light having a predetermined wavelength, excited electrons reduce W ⁶⁺ to generate W ⁵⁺ and the color tone changes. Therefore, it can be used as a sheet for it is dimming with chromic layer containing WO _3.

  Although the thickness of a chromic layer is not specifically limited, From the point which improves a chromic function, 10 nm-1 micrometer are preferable and 100 nm-500 nm are more preferable.

  Moreover, when using the chromic sheet which concerns on this embodiment, for example as a sheet for light control, it is preferable that the chromic layer is further doped with the tetravalent or pentavalent transition metal. Thereby, a part of tungsten in the tungsten oxide is replaced with a tetravalent or pentavalent transition metal, so that the crystallinity is lowered. As a result, the coloring amount of the tungsten oxide is further increased and the photochromic function is more excellent.

  The chromic layer is preferably doped with a tetravalent or pentavalent transition metal of 5.0 mol% or less with respect to tungsten oxide in order to increase the coloring amount of tungsten oxide, and is 2.0 mol%. More preferably, it is doped with ~ 5.0 mol% of tetravalent or pentavalent transition metal. Here, when the tetravalent or pentavalent transition metal is doped by 2.0 mol% to 5.0 mol%, the photochromic function can be further enhanced.

The tetravalent or pentavalent transition metal is not particularly limited, and examples thereof include titanium (Ti), zirconium (Zr), vanadium (V), niobium (Nb), and tantalum (Ta). Is preferred. For example, when the chromic layer includes titanium oxide (TiO ₂ ) and zirconium oxide (WO ₃ ), the photochromic performance can be improved as compared with a case where the chromic layer does not include titanium oxide.

<The manufacturing method of the chromic sheet which concerns on 1st Embodiment>
Although the manufacturing method of the chromic sheet which concerns on 1st Embodiment is not specifically limited, For example, with respect to the base material containing the organic material which has a siloxane skeleton, the precursor containing the particle | grains containing a chromic oxide or the precursor of a chromic oxide only In the method of applying and drying the body fluid, the particles are aggregated or the adhesion to the substrate is poor, and a chromic layer that is easy to peel off is formed.
However, a substrate containing an organic material having a siloxane skeleton is hydrophilized in advance, so that a precursor liquid containing a chromic oxide precursor is applied on the substrate with high uniformity to synthesize a chromic oxide. Therefore, a chromic layer in which aggregation of particles containing a chromic oxide is suppressed can be suitably formed. That is, a suitable method for producing a chromic sheet according to the first embodiment is a step of hydrophilizing at least one surface of a substrate containing an organic material having a siloxane skeleton (hereinafter referred to as “hydrophilization processing step”). And a chromic layer containing the chromic oxide on the base material by applying a precursor liquid containing the chromic oxide precursor on the surface of the base material that has been hydrophilized and drying it. (Hereinafter, sometimes referred to as “drying process”).

(1-1) Hydrophilization treatment step In the hydrophilization treatment step, at least one surface of a substrate containing an organic material having a siloxane skeleton is subjected to a hydrophilic treatment.
The method for hydrophilizing a substrate containing an organic material having a siloxane skeleton is not particularly limited as long as the surface on which the chromic layer is formed can be made hydrophilic with respect to the substrate containing an organic material having a siloxane skeleton, , A step of bringing a treatment liquid containing hydrogen peroxide into contact with at least one surface of the substrate (hereinafter sometimes referred to as “acid treatment step”), or N— on at least one surface of the substrate. Examples include a step of graft polymerization of (2-hydroxyethyl) acrylamide (hereinafter sometimes referred to as “graft polymerization step”).

(1-1A) Acid treatment step Hydrophilization can be achieved by bringing a treatment liquid containing hydrogen peroxide into contact with at least one surface of a substrate containing an organic material having a siloxane skeleton.

  For example, the surface of the substrate can be easily hydrophilized by immersing the substrate including an organic material having a siloxane skeleton in an aqueous solution containing hydrogen peroxide. The concentration of hydrogen peroxide in the aqueous solution is, for example, 1.0 to 8.0 mol / L. In addition to hydrogen peroxide, hydrochloric acid is preferably added to the aqueous solution in order to promote hydrophilicity. The concentration of hydrochloric acid in the treatment liquid is 0.1 to 2.0 mol / L.

By immersing a base material containing an organic material in a treatment solution containing hydrogen peroxide (preferably containing hydrochloric acid) for a predetermined time, the surface of the base material can be easily hydrophilized.
As immersion time, although depending on the concentration of hydrochloric acid and hydrogen peroxide in the treatment liquid, for example, 10 to 48 hours may be mentioned.
Moreover, in order to accelerate | stimulate hydrophilization, it is also preferable to heat a process liquid (for example, 30-80 degreeC) during immersion.

  In addition, when a base material containing an organic material having a siloxane skeleton is immersed in hydrogen peroxide water, bubbles are generated from the surface of the base material and adhered as it is for a long time. There is a possibility that the variation in hydrophilicity will increase at certain locations. Therefore, it is preferable to prevent the bubbles from adhering to the substrate surface for a long time by applying vibration while the substrate is immersed in the hydrogen peroxide solution.

  After a base material containing an organic material having a siloxane skeleton is immersed in hydrogen peroxide water for a predetermined time, the base material is washed with water or the like and dried.

(1-1B) Graft Polymerization Step N- (2-hydroxyethyl) acrylamide (hereinafter sometimes referred to as “HEAAm”) is graft-polymerized on at least one surface of a substrate containing an organic material having a siloxane skeleton. It can also be made hydrophilic. HEAAm is resistant to acid and heat, and is easy to modify the surface of the substrate by graft polymerization onto the surface of the substrate containing an organic material having a siloxane skeleton.

  For example, a substrate containing an organic material having a siloxane skeleton is placed in a glass container, and an acetone solution containing benzophenone is placed in the glass container to clean the surface of the substrate.

  After drying, the HEAAm aqueous solution is placed in a glass container. The concentration of HEAAm in the aqueous solution is, for example, 0.5 to 3.0 mol / L.

Next, each glass container is housed in a sealed container containing an oxygen scavenger to deaerate oxygen.
After deaeration, heating is performed in a drying furnace (for example, 40 to 60 ° C., 1 to 4 hours).

After heating, ultraviolet irradiation (for example, wavelength 365 nm, irradiation time 5 to 30 minutes) is performed, and HEAAm is graft-polymerized on the surface of the base material containing an organic material having a siloxane skeleton.
After UV irradiation, wash with water and dry. Thereby, HEAAm is graft-polymerized on the surface of the base material containing an organic material having a siloxane skeleton, and a hydrophilic film in which HEAAm is graft-polymerized is formed on the surface of the base material.

(1-2) Drying step A chromic oxide containing the chromic oxide on the substrate is obtained by applying a precursor liquid containing a chromic oxide precursor on the surface of the substrate that has been subjected to a hydrophilic treatment, followed by drying. Form a layer.

-Preparation of precursor liquid-
First, a sol solution containing a tungsten component is prepared as a precursor of chromic oxide (tungsten oxide). For example, a sol solution containing a tungsten component can be prepared by adding the tungsten component to a solvent and dissolving it or reacting it if necessary.

  Examples of the tungsten component include tungsten alone or tungsten compounds such as tungsten halide, tungsten alkoxide, tungsten hydroxide, and tungstic acid.

  The solvent for dissolving the tungsten component is not particularly limited, and examples thereof include an organic solvent and water. Examples of the organic solvent include alcohols, ketones, ethers, and the like. More specifically, methanol, ethanol, isopropyl alcohol, n-butyl alcohol, acetone, methyl ethyl ketone, diethyl ether, dipropyl ether, Tetrahydrofuran, 1,4-dioxane and the like can be mentioned. In addition, a solvent may be 1 type and may use 2 or more types together. In addition, an acid, a base, or the like may be added to the solvent.

  The aforementioned solvent may react with a tungsten component such as tungsten alone or tungsten halide. For example, when the tungsten component is tungsten halide (eg, tungsten hexachloride), From the viewpoint of ease of application, etc., alcohol solvents are preferred, ethanol or butanol is more preferred, and tert-butanol is particularly preferred. It is presumed that by dissolving tungsten halide in alcohol, the halogen is dissociated and the alcohol and tungsten ions react to form tungsten alkoxide. In addition, when the tungsten component is tungsten halide (for example, tungsten hexachloride), tungsten halide is used in a nitrogen gas atmosphere or a rare gas atmosphere such as argon in order to suppress the reaction between the tungsten halide and oxygen. It is preferable to dissolve in alcohol.

Moreover, when using the chromic sheet | seat which concerns on 1st Embodiment as a sheet | seat for hydrogen gas sensors, it is preferable to contain platinum (Pt) in order to dissociate a hydrogen molecule in a chromic layer. Therefore, for example, chloroplatinic acid is preferably added as a platinum component to the precursor liquid (sol solution) for forming the chromic layer.
The ratio (molar ratio) between platinum and tungsten in the sol solution is, for example, 1: 1 to 1: 100.

  In addition, when using the chromic sheet | seat which concerns on 1st Embodiment as a sheet | seat for light control, the sol solution containing a tungsten component may contain the tetravalent or pentavalent transition metal component. Thereby, a part of tungsten in the tungsten oxide forming the chromic layer is replaced with a tetravalent or pentavalent transition metal, so that the crystallinity is lowered, and as a result, the coloring amount of tungsten oxide is further increased and more excellent. A chromic layer having a photochromic function can be formed.

  The sol solution containing a tungsten component and a tetravalent or pentavalent transition metal component includes, for example, a tetravalent or pentavalent transition metal, or a halide, alkoxide, or hydroxide of a tetravalent or pentavalent transition metal. It is sufficient to prepare a solution by dissolving it in the above solvent and mixing this solution with a sol solution containing a tungsten component.

  The sol solution containing a tungsten component and a tetravalent or pentavalent transition metal component converts the tetravalent or pentavalent transition metal component into a tungsten component from the viewpoint of increasing the amount of tungsten oxide coloring in the formed chromic layer. It is preferable to contain 5.0 mol% or less with respect to 1.0 mol%-5.0 mol% more preferable. The concentration of the tetravalent or pentavalent transition metal component in the sol solution corresponds to the doping amount of the tetravalent or pentavalent transition metal in the chromic layer. The dope amount of the tetravalent or pentavalent transition metal in the chromic layer can be determined by, for example, diffraction intensity in X-ray diffraction measurement or ICP (inductively coupled plasma) emission spectroscopic analysis.

-Application-
Next, the prepared sol solution containing the tungsten component and the platinum component is applied to the surface of the substrate subjected to the hydrophilic treatment. The method for applying the sol solution to the substrate is not particularly limited, and examples thereof include a dip coating method, a spin coating method, and a roll coating method.

-Drying-
A sol solution containing a tungsten component and a platinum component is applied to the surface of the substrate that has been subjected to a hydrophilic treatment, and then the sol solution applied to the substrate is dried to form a gel layer (chromic layer).
By drying the sol solution containing the tungsten component, the solvent in the sol solution is volatilized, and further, the tungsten component such as tungsten alkoxide is converted into tungsten oxide (WO ₃ ) through a chemical reaction such as hydrolysis and condensation polymerization. The platinum component is precipitated as platinum single particles in a reducing atmosphere during drying, and a gel-like layer (chromic layer) is formed.

The drying temperature and drying time when the sol solution applied to the substrate is dried are the temperature and time at which the tungsten oxide precursor is converted to tungsten oxide (WO ₃ ), but includes an organic material having a siloxane skeleton. What is necessary is just to set also considering the heat resistance of a base material. For example, since the heat resistance of dimethylpolysiloxane is about 250 ° C, the drying temperature is preferably 100 ° C to 250 ° C, and the drying time is preferably 3 minutes to 10 minutes.

After applying the sol solution to the hydrophilized base material, the precursor of tungsten oxide is converted to tungsten oxide by heating and drying. However, due to the heat resistance of dimethylpolysiloxane (about 250 ° C), glass is used as the base material. Heating at a high temperature exceeding 250 ° C. cannot be performed as in the case of using a substrate. Therefore, it is preferable to promote the reaction by dropping, for example, an aqueous hydrochloric acid solution onto the coating film formed on the hydrophilically treated substrate. By dropping an aqueous hydrochloric acid solution onto the coating film, a hydrated tungsten oxide (WO ₃ ) is obtained, and thereafter a tungsten oxide (WO ₃ ) film (chromic layer) can be formed even at a relatively low temperature.

The thickness of the chromic layer can be appropriately set by adjusting the amount and concentration of the sol solution applied to the substrate.
The application and drying may be repeated a plurality of times. For example, a sol solution containing a tungsten component or the like is applied onto a gel layer formed on a hydrophilized substrate, and the applied sol solution is dried to form a gel. These layers (chromic layer) may be further laminated. By repeating the application and drying a plurality of times, the content of the chromic oxide per unit area of the substrate increases, and the chromic function can be improved.

In addition, if a chromic layer is formed by a sol-gel method after hydrophilizing a base material containing an organic material having a siloxane skeleton as described above, it is different from the case of using a sputtering method, a vacuum deposition method, etc. A high quality chromic layer can be formed, and a chromic sheet excellent in chromic performance can be produced.
Moreover, the enlargement of a chromic sheet | seat can also be aimed at by forming a chromic layer by a sol-gel method.

<Chromic sheet according to the second embodiment>
FIG. 2 shows an example of the configuration of the chromic sheet according to the second embodiment. The chromic sheet 20 according to the second embodiment has a configuration in which particles 24 containing a chromic oxide are dispersed in a base material 22 containing an organic material having a siloxane skeleton.
Even in the chromic sheet according to the second embodiment, since a base material including an organic material having a siloxane skeleton is used, the chromic sheet has flexibility, hardly deteriorates due to the photocatalytic action of the chromic oxide, and has excellent gas permeability. ing. Therefore, the chromic sheet according to the second embodiment has a configuration in which tungsten oxide (WO ₃ ) particles are dispersed in a base material containing, for example, dimethylpolysiloxane. It can be used as a light sheet. For example, if the base material containing dimethylpolysiloxane has a configuration in which particles (Pt / WO ₃ particles) containing platinum (Pt) and tungsten oxide (WO ₃ ) are dispersed, the hydrogen gas is based. Since it turns blue when it enters the material, it can be used as a gaschromic sheet.

  The “organic material having a siloxane skeleton” and the “chromic oxide” included in the chromic sheet according to the second embodiment are the same as the materials described in the first embodiment, and description thereof is omitted here.

  The particle diameter of the particles containing the chromic oxide is not particularly limited, but is preferably 10 nm to 60 nm. The particle size of the particles containing the chromic oxide can be adjusted by the particle size, pulverization, sieving, etc. of the raw material used for the production of the particles containing the chromic oxide.

  Although content of the particle | grains containing the chromic oxide in a chromic sheet should just be selected according to a use, it is 0.1-30 mass% from the point which improves a chromic function, for example.

  Although the thickness of a chromic sheet is not specifically limited, 50 micrometers-5 mm are preferable from the point which has a softness | flexibility and improves a chromic function.

  In the chromic sheet according to the second embodiment, since particles containing a chromic oxide are dispersed in a substrate containing an organic material having a siloxane skeleton, for example, hydrogen gas penetrates into the substrate and hydrogen ions are introduced by Pt. Tungsten is reduced by the electrons generated by the dissociation of blue and turns blue. On the other hand, hydrogen ions generated in the substrate react with oxygen and are released as water. The chromic sheet according to the second embodiment discolors when hydrogen gas enters the base material. However, since it takes time until the hydrogen gas is discharged, it can be used as a gas sensor with high memory properties.

<The manufacturing method of the chromic sheet which concerns on 2nd Embodiment>
The method for producing a chromic sheet according to the second embodiment is not particularly limited. For example, in a method of forming a sheet of a dispersion liquid obtained by simply mixing an organic material having a siloxane skeleton and a chromic oxide and curing the sheet, It is difficult to disperse the particles in the substrate due to aggregation of the particles.
However, an uncured organic material having a siloxane skeleton, particles containing a chromic oxide and a solvent are mixed, and dispersion treatment is performed by a bead mill or the like to obtain a dispersion in which the particles containing the chromic oxide are dispersed, By adding a curing agent for curing the uncured organic material having the siloxane skeleton to the dispersion, and forming into a sheet shape, particles containing the chromic oxide are dispersed in the substrate containing the organic material having the siloxane skeleton. Chromic sheet is obtained.
That is, a suitable method for producing a chromic sheet according to the second embodiment includes an uncured organic material having a siloxane skeleton, particles containing a chromic oxide, and a solvent, in which the particles containing the chromic oxide are dispersed. And a curing agent that cures the uncured organic material having the siloxane skeleton is added to the dispersion to form a sheet. And a step of forming a chromic sheet in which particles containing the chromic oxide are dispersed in a base material containing an organic material having the siloxane skeleton (hereinafter sometimes referred to as a “molding step”). Is the method.

(2-1) Dispersion Preparation Step In the dispersion preparation step, an uncured organic material having a siloxane skeleton, particles containing a chromic oxide and a solvent are prepared, and a dispersion in which the particles containing the chromic oxide are dispersed is prepared. To do.
As the particles containing the chromic oxide, commercially available particles may be used, or synthesized particles may be used.

-Production of particles containing chromic oxide-
When manufacturing the particle | grains containing a chromic oxide, it can manufacture by a sol gel process, for example. The particles containing the chromic oxide may be selected depending on the application and the like. Here, the case of producing particles containing tungsten oxide and platinum (Pt / WO ₃ particles) will be described.

  First, a sol solution containing a tungsten component is prepared as a precursor of particles containing chromic oxide (tungsten oxide particles). For example, a sol solution containing a tungsten component can be prepared by adding the tungsten component to a solvent and dissolving it or reacting it if necessary.

  Examples of the tungsten component include tungsten alone or tungsten compounds such as tungsten halide, tungsten alkoxide, tungsten hydroxide, and tungstic acid.

  The solvent for dissolving the tungsten component is not particularly limited, and examples thereof include an organic solvent and water. Examples of the organic solvent include alcohols, ketones, ethers, and the like. More specifically, methanol, ethanol, isopropyl alcohol, n-butyl alcohol, acetone, methyl ethyl ketone, diethyl ether, dipropyl ether, Tetrahydrofuran, 1,4-dioxane and the like can be mentioned. In addition, a solvent may be 1 type and may use 2 or more types together. In addition, an acid, a base, or the like may be added to the solvent.

  Here, the above-mentioned solvent may react with a tungsten component such as tungsten alone or tungsten halide. For example, when the tungsten component is tungsten halide (for example, tungsten hexachloride), Alcohol solvents are preferred. It is presumed that by dissolving tungsten halide in alcohol, the halogen is dissociated and the alcohol and tungsten ions react to form tungsten alkoxide. In addition, when the tungsten component is tungsten halide (for example, tungsten hexachloride), tungsten halide is used in a nitrogen gas atmosphere or a rare gas atmosphere such as argon in order to suppress the reaction between the tungsten halide and oxygen. It is preferable to dissolve in alcohol.

  Also, a sol solution containing a platinum component is prepared as a precursor of platinum particles. For example, a sol solution containing a platinum component can be prepared by adding a platinum component to a solvent and dissolving or reacting as necessary. As the platinum component, for example, chloroplatinic acid can be used, and the solvent is preferably an alcohol solvent. By dissolving chloroplatinic acid in alcohol, chlorine dissociates and exists in the solution in the form of platinum ions. In addition, when the platinum component is chloroplatinic acid, tungsten halide is alcoholized in a nitrogen gas atmosphere or a rare gas atmosphere such as argon in order to suppress the reaction between chloroplatinic acid and water or oxygen in the atmosphere. It is preferable to dissolve in.

After preparing a precursor solution containing a tungsten component (tungsten oxide precursor) and a precursor solution containing a platinum component (platinum precursor), they are mixed to obtain a Pt / WO ₃ precursor solution (sol solution). .
The ratio (molar ratio) of platinum and tungsten in the Pt / WO ₃ precursor solution is, for example, 1:10 to 1: 20,000.

A solid containing Pt / WO ₃ can be obtained by heat-treating the Pt / WO ₃ precursor solution.
The heat treatment is performed, for example, at 40 to 800 ° C. for 1 to 100 hours. The heat treatment may be performed in multiple stages at different temperatures. For example, after the solvent is evaporated by heating at 40 to 70 ° C. as the first heat treatment step, the Pt / WO ₃ precursor is converted to Pt / WO ₃ by heating at 400 to 800 ° C. as the second heat treatment step. Also good. After obtaining a solid containing Pt / WO ₃ through a heat treatment step, Pt / WO ₃ particles can be obtained by pulverization by a pulverizing means such as a bead mill.

  On the other hand, as an uncured (liquid, gel-like, etc.) organic material having a siloxane skeleton, a material that is cured by a reaction with a curing agent to form a base material containing an organic material having a siloxane skeleton may be used. A commercially available product may be used, and SYLGARD 184 (registered trademark, Toray Dow Corning Co., Ltd.) can be suitably used as a commercially available combination of an uncured organic material having a siloxane skeleton and a curing agent.

For example, an uncured organic material having a siloxane skeleton, Pt / WO ₃ powder, and a solvent are mixed to perform dispersion treatment.
As the solvent used here, an alcohol solvent is preferable, and tert-butanol is more preferable from the viewpoint of reducing the viscosity.
Further, the dispersion treatment is not particularly limited as long as a dispersion liquid in which Pt / WO ₃ particles are dispersed is obtained, and examples thereof include stirring and mixing by a ball mill, a jet mill, a bead mill, a colloid mill, a conical mill, a disk mill, and the like.

After obtaining a suspension in which Pt / WO ₃ particles are dispersed by a dispersion treatment, centrifugation is performed, thereby including a precipitate, an uncured organic material having a siloxane skeleton, particles containing a chromic oxide, and a solvent. A dispersion is obtained.

(2-2) Molding step In the molding step, an organic material having the siloxane skeleton is formed by adding a curing agent that cures the uncured organic material having the siloxane skeleton to the dispersion and molding the dispersion into a sheet shape. A chromic sheet is formed in which particles containing the chromic oxide are dispersed in a substrate.

The centrifuged dispersion is extracted, stirred and heated, and a curing agent is added.
Next, the dispersion liquid to which the curing agent is added is poured into a mold having a desired shape, formed into a sheet shape, deaerated, and then cured by heat treatment.
The heat treatment depends on the type of organic material having a siloxane skeleton to be used, but is dimethylpolysiloxane, for example, 40 to 120 ° C., 30 minutes to 10 hours. The heat treatment may be performed in a plurality of stages by changing the temperature. For example, the first heat treatment step is heated at 40 to 60 ° C. to volatilize the solvent, and then the second heat treatment step is heated at 80 to 120 ° C. By curing by heat treatment, a chromic sheet in which Pt / WO ₃ particles are dispersed in a substrate containing an organic material having a siloxane skeleton is obtained.

<Chromic sheet according to the third embodiment>
The chromic sheet according to the third embodiment has a configuration in which a chromic layer in which particles containing a chromic oxide are dispersed in an organic material having a siloxane skeleton is laminated on the surface of a resin base material.

(Resin base material)
In the chromic sheet according to the third embodiment, it is not necessary to use a base material containing an organic material having a siloxane skeleton as a base material, and a base material made of another resin having optical transparency can be used. For example, a transparent resin substrate such as polyester, polyethylene, or polyimide can be used.

(Chromic layer in which particles containing chromic oxide are dispersed in an organic material having a siloxane skeleton)
The chromic layer in the third embodiment has a configuration in which particles containing a chromic oxide are dispersed in an organic material having a siloxane skeleton.
As the organic material having a siloxane skeleton, the organic material having a siloxane skeleton described in the first embodiment or the second embodiment can be used.
As the particles containing the chromic oxide, the particles containing the chromic oxide described in the second embodiment can be used.

The chromic layer in 3rd Embodiment can apply the same structural material and manufacturing method as the chromic sheet which concerns on 2nd Embodiment, for example except being laminated | stacked on the said resin base material.
In the chromic sheet according to the third embodiment, an organic material having a siloxane skeleton functions like an adhesive, and an organic material having a siloxane skeleton exists around particles including the chromic oxide, and includes the chromic oxide. The particles do not contact the resin substrate directly or hardly contact. Therefore, the chromic sheet according to the third embodiment also has high durability with respect to the photocatalytic action, and the chromic layer and the base material each include a resin, and thus have flexibility.

[Usage]
The chromic sheet according to the present embodiment includes a base material including an organic material having a siloxane skeleton that is excellent in flexibility, gas permeability, light permeability, heat resistance, and the like. Therefore, the chromic sheet according to the present embodiment can be attached as a gas sensor sheet in accordance with, for example, the outer peripheral surface of the gas pipe or the shape of the seal portion, and the gas leak location can be specified with high accuracy.

  Moreover, since the chromic oxide discolors by the ultraviolet rays contained in sunlight, the chromic sheet according to the present embodiment can be suitably used as a light control sheet by being attached to a window glass of a building or an automobile, for example. . For example, tungsten oxide turns blue by ultraviolet light and easily absorbs light in the infrared region of 900 nm or more. Therefore, if the chromic sheet according to the present embodiment is used as a light control sheet and attached to a window glass, a heat shielding effect can be expected, a temperature change in the room can be suitably adjusted, and air conditioning efficiency can be improved. Is also possible.

  In addition, chromic oxides such as tungsten oxide also have photocatalytic action, but organic materials having a siloxane skeleton have high durability against photocatalytic action. It can also be used as an antifouling sheet having a cleaning function.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples.

[Example 1]
<Preparation of chromic sheet 1>
The chromic sheet 1 was produced according to the following procedure along the flow shown in FIG.

(1-1A) Hydrophilization with mixed acid treatment solution A mixed acid aqueous solution obtained by mixing 50 mL of 1M HCl aqueous solution and 50 mL of 25% hydrogen peroxide water is maintained at 60 ° C., and a dimethylpolysiloxane sheet (SYKGARD, Toray Dow Corning) (Registered Trademark) 184, thickness 5 mm, hereinafter referred to as “PDMS sheet” in some cases) was immersed for 24 hours.
After immersion, the PDMS sheet was washed with pure water and dried. As a result, a hydrophilic PDMS sheet (hydrophilic PDMS sheet) was obtained.

(1-2A) Formation of chromic layer Solution (concentration: 0.252 mol / L) obtained by adding tungsten hexachloride (WCl ₆ , manufactured by Kojundo Chemical Laboratory Co., Ltd.) to ethanol under a nitrogen atmosphere. ) Was stirred for 1 hour to prepare a sol solution (W sol solution) containing a tungsten component.
Under a nitrogen atmosphere, ethanol chloroplatinic acid _{(H 2 PtCl 6 · 6H 2} O, KANTO CHEMICAL Co., Ltd.) obtained by addition of a solution (concentration: 0.049 mol / L) was stirred for 1 hour Thus, a solution containing a platinum component (Pt solution) was prepared.
The W sol solution and the Pt solution were mixed at a molar ratio of Pt: W = 1: 13 and stirred for 1 hour to obtain a Pt / WO ₃ precursor solution.

The Pt / WO ₃ precursor solution is dropped onto a hydrophilic PDMS sheet and spin coated (1st step; 1,500 rpm, 5 seconds, 2nd step; 3,000 rpm, 15 seconds), and then dried at 100 ° C. for 5 minutes. It was.

  After drying, it was kept in an aqueous 1 M HCl solution at 70 ° C. for 5 minutes.

Next, spin coating, drying (100 ° C., 5 minutes) of the Pt / WO ₃ precursor solution, and holding in an aqueous HCl solution (70 ° C., 5 minutes) were repeated twice, and finally drying at 100 ° C. for 1 minute. I let you.
This gave a chromic sheet 1 chromic layer is formed containing Pt and WO ₃ on one surface of PDMS sheet.

[Evaluation]
<Gas chromic performance>
FIG. 4 is a diagram showing a change in color before and after placing the chromic sheet 1 manufactured in Example 1 in 100% hydrogen gas. The region where the chromic layer of the chromic sheet 1 was formed had a yellowish color in the atmosphere, but it changed to blue in 1 to 2 seconds when placed in 100% hydrogen gas.

When the chromic sheet 1 produced in Example 1 was placed in an atmosphere containing 1% hydrogen and then placed in the air, the absorbance to light having a wavelength of 800 nm was measured. The absorbance was measured using an ultraviolet-visible spectrophotometer U-2910 manufactured by Hitachi High-Technologies Corporation.
Furthermore, after heating the chromic sheet 1 manufactured in Example 1 at 250 ° C. for 3 hours, the absorbance with respect to light having a wavelength of 800 nm was measured in the same manner as described above.
FIG. 5 shows the change in absorbance (wavelength 800 nm) when the chromic sheet 1 manufactured in Example 1 is placed in a gas containing 1% hydrogen and then placed in the atmosphere before and after heat treatment at 250 ° C. ing. In FIG. 5, the vertical axis represents absorbance with respect to light having a wavelength of 800 nm, the horizontal axis represents elapsed time, and “1% H ₂ ” represents the time point when the chromic sheet was placed in an atmosphere containing 1% hydrogen. “Air” indicates the time when the chromic sheet was transferred from the atmosphere containing 1% hydrogen to the atmosphere.
As can be seen in FIG. 5, the absorbance changes greatly at the time when the chromic sheet is placed in the atmosphere containing 1% hydrogen and the time when it is moved to the atmosphere before and after heating, and 1% concentration of hydrogen. It turns out that it responds sufficiently also to gas. In addition, after the heat treatment at 250 ° C. for 3 hours, although the change in absorbance with respect to 1% hydrogen gas is slightly lower than that before heating, it shows sufficient response and can be used as a gas sensor even at high temperatures.

[Example 2]
<Preparation of chromic sheet 2>
In the formation of the chromic layer of the chromic sheet 1 produced in Example 1, chromic layer was formed in the same manner as in Example 1 except that titanium tetrachloride was used in addition to tungsten hexachloride and a chromic layer containing TiO ₂ / WO ₃ was formed. Sheet 2 was produced.

[Evaluation]
<Photochromic performance>
The chromic sheet 2 produced in Example 2 was irradiated with ultraviolet light (UV) having a wavelength of 254 nm for 60 minutes. FIG. 6 shows a change in color before and after irradiating the chromic sheet 1 manufactured in Example 2 with ultraviolet light (254 nm). The color of the region where the chromic layer of the chromic sheet 2 was formed was changed by UV irradiation.
About the chromic sheet 2 before and after UV irradiation, the light transmittance in a 300-1100 nm wavelength range is measured using Hitachi High-Technologies Corp. make ultraviolet visible spectrophotometer U-2910, and the light transmittance before and after UV irradiation is measured. This is shown in FIG. As shown in FIG. 7, there was almost no difference in light transmittance before and after UV irradiation in the wavelength range of 350 to 800 nm, but in the long wavelength region exceeding 800 nm, the light transmittance after UV irradiation was reduced. This is thought to be due to the increase in light absorption in the long wavelength region due to the change in the color of the chromic sheet by UV irradiation.

[Example 3]
<Preparation of chromic sheet 3>
The chromic sheet 3 was produced according to the following procedure along the flow shown in FIG.

(Hydrophilic treatment with HEAAm)
A dimethylpolysiloxane sheet (SYKGARD (registered trademark) 184, Toray Dow Corning Co., Ltd., thickness 5 mm, hereinafter sometimes referred to as “PDMS sheet”) is placed in a petri dish (diameter 70 mm), and 5 mL of a 10% by weight benzophenone acetone solution Was put into a petri dish, and after 1 minute, the PDMS sheet was washed.
After drying, 7 mL of 0.5-3.0 M HEAAm aqueous solution was placed in the petri dish, and the petri dish was placed in a sealed container containing a deoxidizing agent to deaerate oxygen.
The sealed container was placed in a drying furnace and heated at 60 ° C. for 4 hours.
After heating, ultraviolet (365 nm) irradiation was performed for 10 minutes.
Thereafter, washing was performed to obtain a hydrophilic PDMS sheet whose surface was modified with HEAAm.

(Formation of chromic layer)
Under a nitrogen atmosphere, a solution (concentration: 0.252 mol / L) obtained by adding tungsten hexachloride (WCl ₆ , manufactured by Kojundo Chemical Laboratory Co., Ltd.) to ethanol was stirred for 1 hour to obtain a tungsten component. A sol solution containing W (W sol solution) was prepared.
Under a nitrogen atmosphere, ethanol chloroplatinic acid _{(H 2 PtCl 6 · 6H 2} O, KANTO CHEMICAL Co., Ltd.) was obtained by addition of a solution (concentration: 0.049 mol / L) for 1 hour stirring Thus, a solution containing a platinum component (Pt solution) was prepared.

The W sol solution and the Pt solution were added to tert-butanol at a molar ratio of Pt: W = 1: 13, mixed, and stirred for 1 hour to obtain a Pt / WO ₃ precursor solution. In addition, ethanol and tert-butanol in the Pt / WO ₃ precursor solution were in a molar ratio of 1: 3.

The Pt / WO ₃ precursor solution is dropped onto a hydrophilic PDMS sheet and spin coated (1st step; 1,500 rpm, 5 seconds, 2nd step; 3,000 rpm, 15 seconds), and then dried at 100 ° C. for 5 minutes. It was.

  After drying, it was kept in an aqueous 1 M HCl solution at 70 ° C. for 5 minutes.

Next, spin coating, drying (100 ° C., 5 minutes) of the Pt / WO ₃ precursor solution, and holding in an aqueous HCl solution (70 ° C., 5 minutes) were repeated twice, and finally drying at 100 ° C. for 1 minute. I let you.
This gave a chromic sheet 3 chromic layer is formed containing Pt and WO ₃ to chemically modified surfaces in HEAAm of PDMS sheet.

[Evaluation]
<Gas chromic performance>
When the chromic sheet 3 produced in Example 3 was placed in an atmosphere containing 1% hydrogen, it turned blue.
Further, after the color change, no peeling of the chromic layer was observed even when the chromic sheet 3 was bent by hand as shown in FIG.

[Example 4]
<Preparation of chromic sheet 4>
The chromic sheet 4 was produced according to the following procedure along the flow shown in FIG.

(Preparation of particles containing chromic oxide)
Under a nitrogen atmosphere, a solution (concentration: 0.252 mol / L) obtained by adding tungsten hexachloride (WCl ₆ , manufactured by Kojundo Chemical Laboratory Co., Ltd.) to ethanol was stirred for 1 hour to obtain a tungsten component. A sol solution containing W (W sol solution) was prepared.
Under a nitrogen atmosphere, ethanol chloroplatinic acid _{(H 2 PtCl 6 · 6H 2} O, KANTO CHEMICAL Co., Ltd.) was obtained by addition of a solution (concentration: 0.49 mmol / L) for 1 hour stirring Thus, a solution containing a platinum component (Pt solution) was prepared.
The W sol solution and the Pt solution were mixed at a molar ratio of Pt: W = 1: 1300 and stirred for 1 hour to obtain a Pt / WO ₃ precursor solution.
A solid obtained by heat-treating the Pt / WO ₃ precursor solution at 120 ° C. for 12 hours and at 500 ° C. for 1 hour was pulverized by a bead mill (using zirconia beads) to obtain a powder.

About the obtained powder, the measurement by XRD and the observation by FE-SEM were performed. The measurement result of XRD is shown in FIG. 11, and the observation image of FE-SEM is shown in FIG. From these measurement results and observation results, it was confirmed that Pt / WO ₃ composite particles having a particle size of about 30 nm were obtained.

(Preparation of particle dispersion containing chromic oxide)
0.4 g of Pt / WO ₃ composite particles (Pt / WO ₃ powder), 5 mL of base material of SYLGARD 184 (registered trademark, Toray Dow Corning), 20 mL of tert-butanol, 1500 rpm, 60 minutes, bead mill (Bead type: diameter 0.8 μm zirconia beads 20 mL) was agitated.
The obtained Pt / WO ₃ dispersion suspension was centrifuged at 4800 rpm for 30 minutes to obtain a dispersion from which precipitates were removed.

(Sheet molding)
The obtained dispersion was stirred at 100 rpm for 30 minutes while being heated at 120 ° C., and 0.4 g of a curing agent of SYLGARD 184 (registered trademark, Toray Dow Corning) was added, and then poured into a mold (stainless steel dish). It is.
After deaeration for 30 minutes, heat treatment was performed at 60 ° C. for 1 hour and further at 100 ° C. for 1 hour.
As a result, a chromic sheet 4 (thickness 1.1 mm) in which Pt / WO ₃ particles were dispersed in a PDMS substrate was obtained.

[Evaluation]
<Gas chromic performance>
When the chromic sheet 4 produced in Example 4 was exposed to an atmosphere containing 100% hydrogen for 15 minutes, the color of the chromic sheet changed as shown in FIG.
Moreover, about the chromic sheet 4 before and behind exposing to 100% hydrogen atmosphere, the light transmittance of a 300-1100 nm wavelength range was measured using the JASCO Corporation company make and ultraviolet visible spectrophotometer V-630. FIG. 14 shows the change in light transmittance before and after exposing the chromic sheet 4 to a 100% hydrogen atmosphere. As shown in FIG. 14, in the wavelength region of 550 nm or less, the difference in light transmittance before and after UV irradiation was small, but in the wavelength region exceeding 800 nm, the light transmittance after exposure to hydrogen decreased by 30% or more.
Moreover, it was confirmed that the chromic sheet which turned blue by exposure to hydrogen can be easily deformed by hand, and exhibits color response without impairing the flexibility of the polymer.

<Memory performance>
About the chromic sheet 4 manufactured in Example 4, the time required for coloring and decoloring when moved from the 100% hydrogen atmosphere to the air was evaluated. It can be said that the longer the time required for decolorization after moving to the atmosphere after coloring by hydrogen exposure, the better the memory performance.
FIG. 15 shows a change in transmittance with respect to light having a wavelength of 800 nm after the chromic sheet 4 manufactured in Example 4 was exposed to 100% hydrogen atmosphere and then placed in the atmosphere. After coloring due to exposure to hydrogen, even when moved to the atmosphere, it gradually fades, indicating that it has excellent memory performance.

For comparison, the memory performance was evaluated in the same manner as described above for a chromic glass substrate (Comparative Example 1) in which a chromic layer was formed by coating a dispersion containing Pt / WO ₃ on a glass substrate. FIG. 16 shows that after a chromic glass substrate (Comparative Example 1) in which a dispersion containing Pt / WO ₃ particles is coated on a glass substrate to form a chromic layer is exposed to a 100% hydrogen atmosphere, It is a figure which shows the change (memory performance) of light transmittance (wavelength 800nm). As shown in FIG. 16, in a chromic glass substrate in which a chromic layer containing Pt / WO ₃ particles is formed on a glass substrate, coloring by hydrogen exposure is fast, but decolorization in the air is fast and memory performance is poor. I understand.

Claims (12)

(1) A configuration in which a chromic layer containing a chromic oxide is laminated on the surface of a substrate containing an organic material having a siloxane skeleton,
(2) A structure in which particles containing a chromic oxide are dispersed in a substrate containing an organic material having a siloxane skeleton, or (3) a chromic oxide in an organic material having a siloxane skeleton on the surface of a resin substrate. The chromic sheet | seat which has the structure by which the chromic layer in which the particle | grains containing are disperse | distributed is laminated | stacked.   The chromic sheet according to claim 1, wherein the organic material having a siloxane skeleton is dimethylpolysiloxane.   The chromic sheet according to claim 1 or 2, wherein the chromic oxide is an oxide containing at least one metal atom selected from the group consisting of tungsten, vanadium, niobium, tantalum, zirconium, and chromium.   The chromic sheet according to any one of claims 1 to 3, wherein the particles containing the chromic oxide are particles containing tungsten oxide and platinum.   The chromic sheet according to any one of claims 1 to 4, wherein the chromic sheet is for a gas sensor or for dimming. A step of hydrophilizing at least one surface of a substrate containing an organic material having a siloxane skeleton;
Forming a chromic layer containing the chromic oxide on the substrate by applying and drying a precursor liquid containing a chromic oxide precursor on the hydrophilic-treated surface of the substrate;
A method for producing a chromic sheet having   The step of hydrophilizing is a step of bringing a treatment liquid containing hydrogen peroxide into contact with at least one surface of the substrate, or N- (2-hydroxyethyl) acrylamide on at least one surface of the substrate. The method for producing a chromic sheet according to claim 6, comprising a step of graft polymerization. Preparing an uncured organic material having a siloxane skeleton, particles containing a chromic oxide and a solvent, and preparing a dispersion in which the particles containing the chromic oxide are dispersed;
The chromic oxide is contained in the base material containing the organic material having the siloxane skeleton by adding a curing agent for curing the uncured organic material having the siloxane skeleton to the dispersion and forming the sheet into a sheet shape. Forming a chromic sheet in which particles are dispersed;
A method for producing a chromic sheet having   The method for producing a chromic sheet according to claim 8, wherein the solvent is tert-butanol.   The method for producing a chromic sheet according to any one of claims 6 to 9, wherein the organic material having a siloxane skeleton is dimethylpolysiloxane.   The particle containing the chromic oxide is an oxide particle containing at least one metal atom selected from the group consisting of tungsten, vanadium, niobium, tantalum, zirconium, and chromium. A method for producing a chromic sheet according to item 1.   The method for producing a chromic sheet according to any one of claims 6 to 11, wherein the particles containing the chromic oxide are particles containing tungsten oxide and platinum.