JP2018151515A - Thermochromic film and production method of thermochromic film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermochromic film excellent in hue adaptability, thermal crack resistance and thermochromic property, and a production method of the film.SOLUTION: The thermochromic film of the present invention has a dielectric multilayer unit on a substrate, the multilayer unit having at least one thermochromic layer containing vanadium dioxide-containing particles that show thermochromic property and composed of two types of layers having refractive indices different by 0.05 or more from each other, in which the number of whole constituent layers is at least 3. A single layer constituting the dielectric multilayer unit has a thickness of less than 1.0 μm. A maximum reflection peak value of the dielectric multilayer unit is present in a visible light region.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a thermochromic film and a method for producing a thermochromic film. More specifically, the present invention relates to a thermochromic film having a large range of thermal barrier properties at low and high temperatures, excellent color tone suitability, and excellent thermal crack resistance and thermochromic properties. And a manufacturing method thereof.

  In recent years, in order to reduce the heat felt by human skin due to the influence of sunlight entering from a car window, laminated glass having high heat insulating properties or heat shielding properties has been distributed in the market. Recently, with the spread of electric vehicles and the like, development of near-infrared light (heat ray) shielding films applied to laminated glass has been actively conducted from the viewpoint of increasing the cooling efficiency in the vehicle.

  The near-infrared light shielding film can be applied to a vehicle body or a window glass of a building to reduce a load on a cooling facility such as an air conditioner in the vehicle, and is an effective means for energy saving.

  As such a near-infrared light shielding film, an optical film containing a conductor such as ITO (indium tin oxide) as an infrared absorbing substance is known. Japanese Unexamined Patent Application Publication No. 2010-222233 discloses a near-infrared light shielding film including a functional plastic film having an infrared reflection layer and an infrared absorption layer. Furthermore, International Publication No. 2013/065679 has a reflective layer laminate in which a large number of low refractive index layers and high refractive index layers are alternately laminated, and by adjusting the thickness of each refractive index layer, A near infrared light shielding film that selectively reflects near infrared light has been proposed.

  However, these near-infrared light shielding films are preferably used in the low-latitude zone near the equator where the illuminance of sunlight is high due to the high near-infrared light shielding effect. On the other hand, there is a problem that even when it is desired to capture sunlight as much as possible into the vehicle or the room, the incident light is uniformly shielded.

In order to solve such a problem, a method of applying a thermochromic material in which the optical properties of near-infrared light shielding and transmission are controlled by temperature has been studied. A typical material is vanadium dioxide (hereinafter also referred to as “VO ₂ ”). It is known that the vanadium dioxide-containing particles cause a phase transition in a temperature range of about 50 to 60 ° C. and exhibit thermochromic properties.

  This thermochromic rutile vanadium dioxide nanoparticles are added to a resin binder, and a thin film containing vanadium dioxide is formed on a transparent substrate to form a thermochromic near-infrared light shielding film. can do.

  However, this thin film containing vanadium dioxide nanoparticles exhibits a strong yellow coloration due to the intrinsic absorption of vanadium dioxide, so it is not preferable as a near-infrared light shielding film applied to general car windows and building window glass. It was an obstacle to practical use.

  For the above problem, by adjusting the color tone by applying a magenta or cyan coloring material (coloring material such as a dye) or a coloring base material based on the complementary color principle, strong yellow due to the intrinsic absorption of vanadium dioxide, A neutralization method has been proposed (see, for example, Patent Document 1).

  However, in the method described in Patent Document 1, since a color material is used as a color tone adjusting means, and this color material absorbs heat energy and easily generates heat, the glass provided with the thermochromic film is likely to break. . In addition, since the difference in heat shielding properties between low and high temperatures in the near infrared region is reduced, the effect as a thermochromic film is reduced.

In addition to the method using a color material, a laminated structure of TiO ₂ / VO ₂ / TiO ₂ or TiO ₂ / VO ₂ / TiO ₂ / VO ₂ / TiO ₂ is formed by sputtering as a thermochromic film. The method is described (for example, refer nonpatent literature 1). According to this method, the visible light transmittance is increased by the three-layer configuration, and the transmittance in the infrared region is increased by the five-layer configuration. In addition, a configuration in which VO ₂ is sandwiched between amorphous silicon (a-Si) and SiO ₂ is described (for example, see Non-Patent Document 2). This method describes a method for controlling a transmittance spectrum by interference.

However, Non-Patent Document 1 and Non-Patent Document 2 describe a method of adjusting the optical spectrum by forming a laminated body of VO ₂ and other layers. There is no description or report on how to create a function.

Japanese Patent No. 5147034

Thermochromic multilayer films of VO2 and TiO2 with enhanced transmission. (2009) Solar Energy Materials & Solar Cells, 93, 1685-1687. Control of thermochromic spectrum in vanadium dioxide by amorphous silicon sublayer layer. (2008) Solar Energy Materials & Solar Cells, 92, 1279-1284.

  The present invention has been made in view of the above problems and situations, and the solution is to have excellent thermochromic properties, a large range of thermal barrier change at low and high temperatures, excellent color tone, and heat. A thermochromic film having good crack resistance and a method for producing the same.

  As a result of examining the cause of the above-mentioned problem in order to solve the above-mentioned problems, the present inventor has a thermochromic layer containing vanadium dioxide-containing particles exhibiting at least one layer of thermochromic property on a substrate, and is refracted. The dielectric multilayer unit is composed of two types of layers having a ratio of 0.05 or more and the total number of constituent layers is at least three, and the thickness of a single layer constituting the dielectric multilayer unit is a specific thickness. The thermochromic film is characterized in that the maximum reflection peak value of the dielectric multilayer unit is in the visible light range, and has excellent thermochromic properties, and the range of change in heat shielding properties at low and high temperatures. Has been found to be able to realize a thermochromic film having a large thickness, excellent color tone, and good thermal cracking resistance, leading to the present invention.

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

1. A thermochromic film having a thermochromic layer containing vanadium dioxide-containing particles exhibiting thermochromic properties on a substrate,
It has a dielectric multilayer unit composed of two types of layers having different refractive indexes of 0.05 or more, and the total number of constituent layers is at least three.
The layer thickness of a single layer constituting the dielectric multilayer unit is less than 1.0 μm,
And the maximum reflection peak value of the said dielectric multilayer unit exists in a visible light region. The thermochromic film characterized by the above-mentioned.

  2. The thermochromic according to item 1, wherein any one of the two types of layers having a refractive index of 0.05 or more is a thermochromic layer containing vanadium dioxide-containing particles exhibiting the thermochromic property. the film.

  3. 3. The thermochromic film according to item 1 or 2, wherein the dielectric multilayer unit has a configuration in which the total number of layers is laminated within a range of 5 to 31 layers.

  4). 4. The thermo according to claim 1, wherein a difference in refractive index between two kinds of layers having different refractive indexes constituting the dielectric multilayer unit is 0.10 or more. 5. Chromic film.

  5. Of the two types of layers having different refractive indexes constituting the dielectric multilayer unit, the layer having a refractive index different from that of the thermochromic layer is a layer containing silica particles and a binder. The thermochromic film as described in any one of Claim 4 thru | or 4.

  6). The layer thickness of each constituent layer excluding the uppermost layer and the lowermost layer of the dielectric multilayer unit is in the range of 50 to 150 nm, respectively, characterized in that it is any one of items 1 to 5. Thermochromic film.

  7). The thermochromic film according to any one of Items 1 to 6, wherein the thermochromic layer includes vanadium dioxide-containing particles and a binder.

  8). The thermochromic film according to any one of items 1 to 7, wherein a vanadium dioxide-containing particle concentration in the thermochromic layer is in a range of 2 to 30% by mass.

  9. Any one of Items 1 to 8, wherein a difference between a reflectance at a maximum reflection peak value in a visible light region of the dielectric multilayer unit and a reflectance at 1000 nm is 5.0% or more. The thermochromic film according to one item.

  10. The thermochromic film according to any one of Items 1 to 9, which has a dielectric multilayer unit having two layers having different refractive indexes of 0.05 or more and a total number of constituent layers of at least three. A method for producing a thermochromic film, comprising producing the thermochromic film.

  11. The method for producing a thermochromic film according to item 10, wherein the layers constituting the dielectric multilayer unit are formed by a wet coating method.

  By the above means of the present invention, there is provided a thermochromic film having excellent thermochromic properties, large heat-insulating change width at low and high temperatures, excellent color tone, and good thermal cracking resistance, and a method for producing the same. can do.

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

  In the thermochromic film of the present invention, by forming a dielectric multilayer unit composed of two types of layers having different refractive indexes of 0.05 or more and having a total number of layers of at least three, light in the visible light region can be obtained. A thermochromic film that specifically reflects can be realized. In this way, by reflecting the light in the visible light region, it is possible to compensate for yellow coloring caused by vanadium dioxide-containing particles without adding a coloring material, and to adjust to an appropriate color tone as a thermochromic film, and to cause thermal cracking. It is possible to produce a thermochromic film that hardly occurs.

Schematic sectional view showing an example of the configuration of the thermochromic film of Comparative Example 1 The graph which shows an example of the transmission spectrum of the thermochromic film of the comparative example 1 Schematic sectional view showing an example of the configuration of the thermochromic film of Comparative Example 2 having a pigment layer The graph which shows an example of the transmission spectrum of the thermochromic film of the comparative example 2 Schematic sectional view showing an example of the configuration of the thermochromic film of the present invention The graph which shows an example of the transmission spectrum of the thermochromic film of this invention The graph which shows an example of the reflection spectrum of the thermochromic film of this invention Schematic sectional view showing another example of the configuration of the thermochromic film of the present invention Schematic which shows an example of the flow-type reaction apparatus which comprises the hydrothermal reaction part applicable to manufacture of the vanadium dioxide containing particle | grains based on this invention.

  The thermochromic film of the present invention has a thermochromic layer containing vanadium dioxide-containing particles exhibiting thermochromic properties on a base material, and is composed of two types of layers having different refractive indexes of 0.05 or more. A dielectric multilayer unit having at least three layers, the thickness of a single layer constituting the dielectric multilayer unit is less than 1.0 μm, and the maximum reflection peak value of the dielectric multilayer unit is It is characterized by being in the visible light range. This feature is a technical feature common to the claimed invention.

  The visible light region referred to in the present invention is a wavelength region in the range of 380 to 780 nm.

  In the thermochromic film of the present invention, from the viewpoint that the effect intended by the present invention can be expressed more, any one of two kinds of layers having a refractive index different by 0.05 or more contains vanadium dioxide showing the thermochromic property. A thermochromic layer containing particles is preferable in that it can exhibit more excellent thermochromic properties.

  In addition, it is possible to obtain a desired thermochromic property that the dielectric multilayer film unit has a configuration in which the total number of layers is laminated within a range of 5 to 31 layers. It is preferable from the viewpoint of suppressing cracks.

  Moreover, it is preferable from the viewpoint that the refractive index difference between two types of layers having different refractive indexes constituting the dielectric multilayer film unit is 0.10 or more, so that the infrared reflectance can be increased with a small number of layers.

  Of the two layers having different refractive indexes constituting the dielectric multilayer unit, the layer having a refractive index different from that of the thermochromic layer is a layer containing silica particles and a binder. It is preferable in that the desired effect can be further expressed and the product can be produced with high productivity.

  In addition, it is preferable that the thickness of each constituent layer excluding the uppermost layer and the lowermost layer of the dielectric multilayer unit is in the range of 50 to 150 nm, respectively, from the viewpoint that thermochromic properties can be expressed more efficiently. .

  Moreover, it is preferable that a thermochromic layer contains vanadium dioxide containing particle | grains and a binder at the point which can express thermochromic property more efficiently.

  Moreover, it is preferable that the vanadium dioxide-containing particle concentration in the thermochromic layer is set in the range of 2 to 30% by mass in terms of more efficiently thermochromic expression.

  In addition, the difference between the reflectance at the maximum reflection peak value in the visible light region of the dielectric multilayer unit and the reflectance at 1000 nm is 5.0% or more, and visible light can be specifically reflected. It is preferable at the point which can express the outstanding thermochromic property.

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

《Basic composition of thermochromic film》
The thermochromic film of the present invention has a thermochromic layer containing vanadium dioxide-containing particles exhibiting thermochromic properties on a substrate, and the dielectric multilayer unit formed on the thermochromic film has a refractive index of 0. .05 or more of two different layers, the total number of layers is at least 3, the thickness of a single layer constituting the dielectric multilayer unit is less than 1.0 μm, and the dielectric multilayer unit The maximum reflection peak value is in the visible light range.

  Hereinafter, a typical example of a comparative example (conventional example) and a thermochromic film of the present invention and its transmission spectrum characteristics will be described with reference to the drawings.

  First, the structure of a conventional thermochromic film as a comparative example and its transmission spectrum characteristics will be described.

  FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a thermochromic film as a comparative example.

  As shown in FIG. 1, in the conventional thermochromic film (1), a thermochromic layer (3) as an optical functional layer is formed on a transparent substrate (2A), and an adhesive layer ( The second substrate (2B) is provided via 5), and the clear hard coat layer (4) is provided thereon.

  For example, the thermochromic layer (3) is in a state in which vanadium dioxide-containing particles are dispersed in a binder resin.

  FIG. 2 shows a transmission spectrum from the visible light region to the near infrared region in the thermochromic film having the conventional structure shown in FIG.

  As shown in FIG. 2, in the state in which the thermochromic layer (3) contains vanadium dioxide-containing particles, the transmittance LT (solid line) in the low-temperature environment and the transmission in the high-temperature environment are certainly in the near infrared region. There is a large difference between the rate HT (dashed line) and the difference in thermal insulation (TSER) between the two (hereinafter referred to as “ΔTSER”), but in the visible light region, the vanadium dioxide-containing particles The resulting yellow coloration was an unfavorable characteristic as the appearance of the near infrared light shielding film.

  In order to solve the above problem, as described in the above-mentioned Patent Document 1, a strong yellow color due to the intrinsic absorption of vanadium dioxide is added to a magenta or cyan coloring material (coloring material such as a dye) based on the complementary color principle. A compensation method has been proposed.

  FIG. 3 is a schematic cross-sectional view showing an example of the configuration of a thermochromic film of a comparative example having a pigment layer proposed in Patent Document 1.

  The thermochromic film (1) shown in FIG. 3 has a thermochromic layer (3) that is an optical functional layer formed on a transparent substrate (2A), and the second substrate via the adhesive layer (5). A material (2B) is formed, and a clear hard coat layer (6) containing a pigment is formed thereon.

  In the clear hard coat layer (6), a cyan pigment and a magenta pigment for forming a blue color complementary to the yellow color of vanadium dioxide-containing particles are added as pigments, and corrected to gray coloring as shown in FIG. ing.

  However, by adding the pigment to the outermost layer in this way, the pigment absorbs heat energy, the temperature rises, and thermal cracking is likely to occur. Furthermore, as shown in FIG. 4, the amount of light reaching the thermochromic layer (3) containing vanadium dioxide-containing particles is reduced by the amount of the pigment present in the surface layer that absorbs light, resulting in a decrease in ΔTSER. Have a problem.

  On the other hand, the thermochromic film of the present invention has a thermochromic layer containing vanadium dioxide-containing particles exhibiting at least one layer of thermochromic properties, and has two or more different refractive indexes of 0.05 or more layers. It has a dielectric multilayer unit in which the total number of constituent layers is at least three.

  FIG. 5 is a schematic cross-sectional view showing an example of the configuration of the thermochromic film of the present invention.

  In the thermochromic film (1) shown in FIG. 5, a dielectric multilayer unit (U) is formed on a transparent substrate (2A), and a second substrate is formed thereon via an adhesive layer (5). A material (2B) is provided, and a clear hard coat layer (4) is provided thereon.

  The dielectric multilayer unit (U) is composed of two layers having different refractive indexes of 0.05 or more, and the total number of layers is at least three, one of which contains thermochromic vanadium dioxide. A thermochromic layer containing particles.

In the dielectric multilayer unit (U) shown in FIG. 5, from the transparent base material (2A) side, it is two types of layers having a refractive index different by 0.05 or more, for example, containing SiO ₂ as the first layer The low refractive index layer (7) and the thermochromic layer (3) containing vanadium dioxide-containing particles are laminated to have a configuration. In FIG. 5, as an example, six low refractive index layers (7) and five thermochromic layers (3) are alternately stacked.

  FIG. 6 is a graph showing an example of a transmission spectrum in the thermochromic film having the configuration shown in FIG.

  In the thermochromic film of the present invention, since the dielectric multilayer film unit (U) formed by two kinds of layers having different refractive indexes of 0.05 or more expresses the characteristic of specifically reflecting visible light, it contains vanadium dioxide. It is possible to compensate for the yellow coloring inherent to the particles, and to achieve a neutral color tone without exhibiting a specific coloring. In addition, since unnecessary pigments are not used, it is possible to realize an excellent thermal barrier (TSER) difference ΔTSER in the near infrared region as compared with the configuration shown in FIG.

FIG. 7 shows the reflection spectrum of the thermochromic film having the structure shown in FIG. 5, and the thermochromic film of the present invention is the maximum of the dielectric multilayer unit specific to the visible light region, as is apparent from FIG. It is characterized by having a reflection peak value (λ _max ).

In the present invention, the difference ΔR (%) between the reflectance at the maximum reflection peak value (λ _max ) in the visible light region of the dielectric multilayer unit and the reflectance at 1000 nm is preferably 5.0% or more. is there.

  As a structure of the thermochromic film of this invention, the thermochromic film of the structure shown in FIG. 8 other than the structure shown in FIG. 5 can be mentioned.

  In the thermochromic film shown in FIG. 8, a thermochromic layer (3) containing vanadium dioxide-containing particles having a layer thickness exceeding 1.0 μm is provided on a transparent substrate (2A). Since the thermochromic layer (3) has a thickness exceeding 1.0 μm, the thermochromic layer (3) does not correspond to a constituent layer of the dielectric multilayer unit according to the present invention.

On the thermochromic layer (3), a dielectric multilayer unit (U) composed of two types of layers having a refractive index different by 0.05 or more is provided. As two types of layers having a refractive index different by 0.05 or more constituting the dielectric multilayer unit (U), for example, a low refractive index layer (7) containing SiO ₂ as a first layer, For example, the high refractive index layer (8) containing ZrO ₂ may be alternately stacked. A second substrate (2B) is provided on the adhesive layer (5) thereon, and a clear hard coat layer (4) is provided thereon.

  As the optical characteristics of the thermochromic film of the present invention, the visible light transmittance measured according to JIS R3106-1998 is preferably 60% or more, more preferably 70% or more, and further preferably 80% or more. is there. Moreover, it is preferable to have the area | region exceeding a reflectance of 50% in the area | region of wavelength 900-1400 nm.

[Dielectric multilayer unit]
The dielectric multilayer unit according to the present invention is configured by alternately laminating two types of layers having different refractive indexes of 0.05 or more. The dielectric multilayer unit according to the present invention expresses a function of blocking sunlight, particularly an infrared component. In addition, the dielectric multilayer unit preferably has two types of layers having different refractive indexes of 0.05 or more, and the metal oxide fine particles are preferably included in any one layer.

  In the present invention, the thickness of each constituent layer excluding the uppermost layer and the lowermost layer of the dielectric multilayer unit is about 50 to 800 nm, preferably in the range of 50 to 500 nm, particularly preferably 50 to 500 nm. Within the range of 150 nm.

  Here, when measuring the thickness of each layer of the dielectric multilayer unit, the composition of two types of layers having different refractive indexes of 0.05 or more changes continuously even if there is a clear interface between these layers. The structure to do may be sufficient. When the composition is continuously changed from the interface, the maximum refractive index-minimum refractive index = Δn in the region where the layers are mixed and the refractive index continuously changes. A point of refractive index + Δn / 2 is regarded as a layer interface.

  In the present invention, the metal oxide concentration profile of the dielectric multilayer unit is 0.5 nm / min when the outermost surface is set to 0 nm by performing etching from the surface to the depth direction using a sputtering method and using an XPS surface analyzer. It can be seen by sputtering at a rate of and measuring the atomic composition ratio. It is also possible to confirm the cut surface by cutting the laminated film and measuring the atomic composition ratio with an XPS surface analyzer. In the mixed region, when the concentration of the metal oxide changes discontinuously, the boundary can be confirmed by a tomographic photograph using an electron microscope (TEM).

  The XPS surface analyzer is not particularly limited, and any model can be used. For example, ESCALAB-200R manufactured by VG Scientific, Inc. can be used. Mg is used for the X-ray anode, and measurement is performed at an output of 600 W (acceleration voltage: 15 kV, emission current: 40 mA).

  From the viewpoint of productivity, the dielectric multilayer unit according to the present invention is within the range of 5 to 50 layers as the range of the total number of layers composed of two types of layers having different refractive indexes of 0.05 or more. More preferably, it exists in the range of 5-31 layers. Moreover, from the viewpoint of infrared reflectance and translucency, and suppression of film peeling and cracking due to heating, the preferred total number of high refractive index layers and low refractive index layers is 11 to 31 layers.

  The dielectric multilayer unit is characterized in that the difference in refractive index between the two types of layers is 0.05 or more, but it is designed to be large to some extent to increase the infrared reflectance, which is a heat ray, with a small number of layers. It is preferable from the viewpoint that In the present invention, the difference in refractive index between the two layers constituting the dielectric multilayer unit is preferably 0.10 or more, more preferably 0.30 or more, still more preferably 0.35 or more, particularly Preferably it is 0.40 or more. However, the uppermost layer and the lowermost layer constituting the dielectric multilayer unit may have a configuration outside the above preferred range.

  Moreover, the reflectance in a specific wavelength region is determined by the difference in refractive index between two adjacent layers and the number of stacked layers. The refractive index difference and the required number of layers can be calculated using commercially available optical design software. For example, in order to obtain a near-infrared reflectance of 90% or more, if the difference in refractive index is smaller than 0.1, it is necessary to laminate 200 layers or more, which not only reduces productivity, but also at the lamination interface. Scattering increases, transparency decreases, and it becomes very difficult to manufacture without failure. From the standpoint of improving reflectivity and reducing the number of layers, there is no upper limit to the difference in refractive index, but practically about 1.4 is the limit.

  In the dielectric multilayer unit according to the present invention, a layer configuration in which the lowermost layer adjacent to the transparent resin film is a low refractive index layer is preferable from the viewpoint of adhesion to the substrate.

<Components of thermochromic film>
Hereinafter, each member which comprises the thermochromic film of this invention is demonstrated.

  The thermochromic film of the present invention comprises at least one thermochromic layer containing vanadium dioxide-containing particles exhibiting thermochromic properties, and is composed of two layers having different refractive indexes of 0.05 or more, and is a total constituent layer It is characterized by having a dielectric multilayer unit having at least three layers.

  Preferably, at least one of the two types of layers having different refractive indexes of 0.05 or more is a thermochromic layer containing vanadium dioxide-containing particles exhibiting the thermochromic property.

[Dielectric composition layer]
[Thermochromic layer]
The thermochromic layer according to the present invention is characterized by containing vanadium dioxide-containing particles exhibiting thermochromic properties. Further, it is a preferable aspect that the thermochromic layer contains vanadium dioxide-containing particles and a binder. .

(Vanadium dioxide-containing particles)
Vanadium oxide constituting the vanadium dioxide-containing particles is an embodiment of vanadium oxide. Vanadium oxide takes various forms in nature. For example, V ₂ O ₅ , H ₃ V ₂ O ₇ ⁻ , H ₂ VO ₄ ⁻ , HVO ₄ ²⁻ , VO ₄ ³⁻ , VO ²⁺ , VO ₂ , V ^Examples of the structure include ³⁺ , V ₂ O ₃ , V ²⁺ , VO, and V. The form changes depending on the environmental atmosphere. Generally, V ₂ O ₅ is formed in an oxidizing environment, and V ₂ O ₃ is formed in a reducing environment. Therefore, VO ₂ is relatively easy to oxidize and reduce, and the crystal structure changes depending on the surrounding environment.

As the crystal form of the vanadium dioxide-containing particles according to the present invention, it is preferable to use rutile vanadium dioxide-containing particles (hereinafter also simply referred to as VO ₂ -containing particles) from the viewpoint of efficiently expressing thermochromic properties.

  Since the rutile vanadium dioxide-containing particles have a monoclinic structure below the transition temperature, they are also called M-type.

  The vanadium dioxide-containing particles according to the present invention are preferably present in the optical functional layer in such a manner that the number average particle diameter of the primary particles and the secondary particles is less than 500 nm.

  Various measurement methods can be applied as a method for measuring the particle diameter, but measurement is preferably performed according to a dynamic light scattering method.

<Method for producing vanadium dioxide-containing particles>
In the present invention, as a method for producing vanadium dioxide-containing particles, a vanadium (IV) -containing compound is used as the vanadium-containing compound, and an alkali is used as the compound that reacts with the vanadium-containing compound. This is preferable in that vanadium dioxide-containing particles can be formed.

  In addition, the method of using a vanadium (V) -containing compound as the vanadium-containing compound and applying a reducing agent as the compound that reacts with the vanadium-containing compound similarly forms stable and highly monodispersed vanadium dioxide-containing particles. It is preferable at the point which can do.

  Subsequently, the manufacturing method of the vanadium dioxide containing particle dispersion by the hydrothermal method suitable for this invention is demonstrated in detail.

  In the present invention, the method for producing vanadium dioxide-containing particles is not particularly limited, but as an example, using a flow reactor having a hydrothermal reaction section, a vanadium-containing compound and deaerated water (or ion exchange) Water), a reaction solution obtained by mixing a compound that reacts with the vanadium-containing compound dissolved in deaerated water, and deaerated water (or ion-exchanged water) in a supercritical or subcritical state, A method of producing vanadium dioxide-containing particles by a thermal synthesis method is preferred.

  In the present invention, a method in which a vanadium-containing compound is hydrothermally reacted in the presence of supercritical or subcritical degassed water (or ion-exchanged water) to form vanadium dioxide-containing particles is referred to as “hydrothermal synthesis method”. ”,“ Hydrothermal reaction method ”, and“ hydrothermal reaction ”, and the implementation steps are also referred to as“ hydrothermal reaction steps ”.

[1] Flow-type reaction apparatus In the present invention, the method for producing vanadium dioxide-containing particles uses a flow-type reaction apparatus having a hydrothermal reaction section for hydrothermal reaction using deaerated water (or ion-exchanged water). The method of performing is preferred.

  Hereinafter, an example in which deaerated water is used as dissolved water will be described as a preferred embodiment in which a hydrothermal reaction is performed using a flow reactor. The present invention is not limited to the following form.

Production of vanadium dioxide-containing particles with excellent thermochromic and monodispersed vanadium dioxide-containing particles by carrying out in the presence of degassed water in a supercritical or subcritical state at high pressure in the hydrothermal reaction section And transparency of the optical film can be achieved. The reason for this is that the hydrothermal reaction is carried out in the presence of degassed water in a supercritical or subcritical state under high pressure, thereby suppressing the oxidizing atmosphere during the hydrothermal reaction and reducing the vanadium dioxide having the desired valence. Vanadium dioxide (VO ₂ ) -containing particles that can be produced by a stable reaction and have thermochromic properties can be produced stably.

  When a hydrothermal reaction is performed using a flow reactor, in the hydrothermal reaction section that performs the hydrothermal reaction of the flow reactor, a raw material liquid containing a vanadium-containing compound and deaerated water, and the reaction with the vanadium-containing compound are reacted. The passage time of the reaction solution in which the compound to be mixed and degassed water in a supercritical or subcritical state is mixed is preferably in the range of 4 to 700 seconds, and more preferably in the range of 12 to 700 seconds.

  In the present invention, the reaction solution basically includes 1) a raw material solution containing a vanadium-containing compound (A) and deaerated water, 2) a compound (B) that reacts with the vanadium-containing compound, and 3) supercriticality. Or at least 1) a raw material liquid containing a vanadium-containing compound (A) and degassed water, and 3) a supercritical or subcritical degassed water, respectively. The form in which the compound (B) that reacts with the vanadium-containing compound is allowed to coexist with 1) or 3) is preferable.

  Specifically, in the first method, a raw material liquid container includes 1) a raw material liquid containing a vanadium-containing compound (A) and deaerated water, and 2) a compound (B) that reacts with the vanadium-containing compound, for example, deaerated water. An alkali or a reducing agent dissolved in a predetermined concentration is added to the other raw material liquid container, deaerated water is added as water, and the deaerated water is supercritical or heated at a predetermined temperature and pressure with a heating medium. After degassing water in the subcritical state, both are assembled at the confluence to make a reaction solution, and then hydrothermally treated in the heating pipe in the hydrothermal reaction section that constitutes the hydrothermal reaction section, containing vanadium dioxide A method for preparing particles.

  On the other hand, in the second method, 1) a raw material liquid containing a vanadium-containing compound (A) and degassed water is added to a raw material liquid container, and 2) a compound that reacts with the vanadium-containing compound ( Degassing water containing B) is added, and degassing water containing the compound (B) that reacts with the vanadium-containing compound is degassed in a supercritical or subcritical state with a heating medium at a predetermined temperature and pressure. After preparing water, the two are assembled at a confluence to form a reaction solution, and then hydrothermally treated with a heating section pipe in the hydrothermal reaction section constituting the hydrothermal reaction section to prepare vanadium dioxide-containing particles. is there.

  Next, in the present invention, as an example of a flow reactor applied in the method for producing vanadium dioxide-containing particles, the overall configuration of a flow reactor having a hydrothermal reaction section that can be preferably used will be described with reference to the drawings. .

  FIG. 9 is a schematic view showing an example of a flow reactor having a hydrothermal reaction section that can be applied to the production of vanadium dioxide-containing particles according to the present invention.

  In FIG. 9, a flow reactor (101) having a hydrothermal reaction section is a raw material liquid containing vanadium-containing compound (A), a compound (B) that reacts with a vanadium-containing compound, and degassed water. (Embodiment 1), or a raw material liquid container 1 (105) for containing a raw material liquid (Embodiment 2) containing a vanadium-containing compound (A) and deaerated water, supercritical water or subcritical water as the other constituent liquid Degassed water for forming (Embodiment 1) or raw material liquid container 2 (102) for containing degassed water (Embodiment 2) containing a compound (B) that reacts with a vanadium-containing compound, hydrothermal reaction Hydrothermal reaction section (116) having heating medium (114) to be performed, tank (109) for containing reaction liquid after hydrothermal reaction, raw material liquid container 1 (105), raw material liquid container 2 (102) and tank ( 109) and Channel (pipe, 103 and 106), one of the raw material liquid containing at least the vanadium-containing compound (A) from the raw material liquid container 1 (105), the pipe (106), the junction (MP), and the heating part pipe (117), a pump (107) for sending liquid to the tank (109) via the pipe (118) and the control valve (119), and the other component liquid is stored in the raw material liquid container 2 (102). Degassed water or the like for forming supercritical water or subcritical water is supplied from the raw material liquid container 2 (102) to the pipe (103), the heating medium (113), the junction (MP), and the heating part pipe (117). ), A pump (104) for feeding liquid to the tank (109) via the pipe (118) and the control valve (119).

  Further, the flow reaction device (101) includes a cooling unit (108) including a flow path (118) for cooling the reaction liquid containing the vanadium dioxide-containing particles after the hydrothermal reaction, if necessary. Also good. Moreover, although mentioned later for details, it mixes with the reaction liquid after the surface modifier, pH adjuster, or hydrothermal reaction added to the reaction liquid containing the vanadium dioxide containing particle | grains after a hydrothermal reaction as needed. A tank (110) for containing a cooling medium (for example, water) for cooling, a surface modifier, a pH adjusting agent, a cooling medium, etc. is sent to the flow path (118) via the flow path (111). A pump (112) may be further included.

  The flow type reaction apparatus (101) has heating media (113, 115) in the flow path (106) or the flow path (103) line. In particular, the heating medium (113) arranged in the flow path (103) applies superheated water or degassed water stored in the raw material liquid container 2 (102) to a predetermined temperature and pressure. Form subcritical water.

[2] Hydrothermal reaction step In the present invention, in the hydrothermal reaction step,
1) A reaction liquid obtained by mixing a vanadium-containing compound (A), a raw material liquid containing a compound (B) that reacts with a vanadium-containing compound and degassed water, and degassed water in a supercritical or subcritical state, or 2) A reaction liquid obtained by mixing a raw material liquid containing a vanadium-containing compound (A) and deaerated water and a supercritical or subcritical deaerated water containing a compound (B) that reacts with the vanadium-containing compound. ,
Vanadium dioxide-containing particles are obtained by hydrothermal reaction in the presence of supercritical water or subcritical water in a hydrothermal reaction section to which a predetermined temperature and pressure are respectively applied.

  The compound (B) that reacts with the vanadium-containing compound (A) is not particularly limited as long as it can produce vanadium dioxide-containing particles by hydrothermal reaction of the raw material liquid. Agents and the like.

Specifically (1) When a tetravalent vanadium (IV) -containing compound is used as the vanadium-containing compound (A), an alkali is applied as the compound (B) that reacts with the vanadium-containing compound (A). . At this time, the alkali is added to the raw material liquid containing the vanadium-containing compound (A) and water. In the second embodiment, the alkali is added to water for forming supercritical or subcritical water.

on the other hand,
(2) When a pentavalent vanadium (V) -containing compound is used as the vanadium-containing compound (A), the compound (B) that reacts with the vanadium-containing compound (A) includes a reducing agent (for example, hydrazine and its It is preferable to apply a hydrate or the like. At this time, the reducing agent is added to the raw material liquid containing the vanadium-containing compound (A) and water in the first embodiment, and added to water for forming supercritical or subcritical water.

(About deaerated water)
In the present invention, in the method for producing vanadium dioxide-containing particles, it is preferable that the water applied to the hydrothermal reaction is deaerated water. More specifically, the water constituting the reaction solution containing the vanadium-containing compound (A) that passes through the hydrothermal reaction section and the compound (B) that reacts with the vanadium-containing compound (A) is deaerated water. The deaerated water here is water having an amount of dissolved oxygen at 25 ° C. of 4.0 mg / L or less, preferably 2.0 mg / L or less, more preferably 1.0 mg / L or less, Particularly preferably, it is 0.4 mg / L or less, and when the amount of dissolved oxygen in the reaction solution satisfies the conditions defined above, it is possible to suppress oxidation in the reaction system, decomposition due to oxidation, and prevention of foaming. .

(Hydrothermal reaction conditions: temperature, pressure)
In the present invention, in the method for producing vanadium dioxide-containing particles, in the hydrothermal reaction step, the reaction solution is hydrothermally reacted to form vanadium dioxide-containing particles. The term “hydrothermal reaction” as used herein means a mineral synthesis or alteration reaction, that is, a chemical reaction performed in the presence of high-temperature water, particularly high-temperature and high-pressure water.

  The hydrothermal reaction in the present invention is performed in a state where the temperature is 150 ° C. or higher and the pressure is higher than the saturated vapor pressure, that is, the deaerated water exists in a supercritical or subcritical state. It is characterized by. It is known that by performing the reaction under such high-temperature and high-pressure conditions, a unique reaction occurs due to the presence of degassed water, unlike the case of normal pressure and high temperature where almost no degassed water can exist. Yes. It is also known that the solubility of oxides such as silica and alumina is improved and the reaction rate is improved.

  In the present invention, by performing the hydrothermal reaction under the conditions as described above, the average particle diameter (D) of the formed vanadium dioxide-containing particles and the particle size distribution can be narrowed, and the vanadium dioxide containing The thermochromic property of the particles and the transparency of the optical film containing the vanadium dioxide-containing particles can be improved (decrease in haze).

  In the above example, an example in which degassed water is used as the solvent is shown, but normal ion-exchanged water may be used as necessary.

[Other components of dielectric multilayer unit]
The dielectric multilayer unit according to the present invention is constituted by two types of layers having different refractive indexes of 0.05 or more, and the total number of constituent layers is at least three.

  As described above, it is preferable that one of the two types of layers having different refractive indexes of 0.05 or more is a thermochromic layer containing vanadium dioxide-containing particles exhibiting the thermochromic properties described above. Therefore, the other one layer is preferably a layer having a refractive index different from that of the thermochromic layer by 0.05 or more (hereinafter also referred to as a dielectric layer having a different refractive index).

  When the thermochromic layer containing vanadium dioxide-containing particles forms a single vanadium dioxide layer by vapor deposition or the like, the refractive index of the layer becomes 2.80 which is the refractive index of vanadium dioxide, and an aqueous coating method. In the case of forming with vanadium dioxide-containing particles and a binder, etc., it varies depending on the content ratio of the vanadium dioxide-containing particles and the kind of the binder, but is roughly in the range of 1.5 to 2.7.

  Therefore, other layers having a refractive index different by 0.05 or more are adjusted to select a dielectric material, specifically, the type of metal oxide and the amount of addition so that the refractive index is in that range. What is necessary is just to set so that the relationship may be satisfy | filled.

(Forming material for dielectric layer)
In the present invention, examples of the constituent material of the dielectric layer having a different refractive index of the thermochromic layer containing vanadium dioxide-containing particles exhibiting thermochromic properties include metal oxides.

  As the metal oxide for obtaining a relatively high refractive index, metal oxide particles having a refractive index of 2.0 or more and 3.0 or less are preferable. More specifically, for example, titanium oxide, zirconium oxide, zinc oxide, lead titanate, red lead, yellow lead, zinc yellow, chromium oxide, ferric oxide, iron black, copper oxide, magnesium oxide, hydroxide Examples include magnesium, strontium titanate, yttrium oxide, niobium oxide, europium oxide, lanthanum oxide, zircon, and tin oxide. In addition, composite oxide particles composed of a plurality of metals, core / shell particles whose metal structure changes into a core / shell shape, and the like can also be used.

  In the dielectric multilayer unit according to the present invention, when one is a thermochromic layer, the other layer is formed of a layer having a lower refractive index (hereinafter also referred to as a low refractive index layer). preferable.

  As the metal oxide particles applied to the layer having a lower refractive index than the thermochromic layer according to the present invention, it is preferable to use synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, etc. Examples thereof include crystalline silica and colloidal silica. Of these, acidic colloidal silica sol is more preferably used, and colloidal silica sol dispersed in an organic solvent is more preferably used. Moreover, in order to further reduce the refractive index, hollow fine particles having pores inside the particles can be used as the metal oxide particles applied to the low refractive index layer, and in particular, hollow fine particles of silica (silicon dioxide). Is preferred.

  The metal oxide particles (preferably silicon dioxide) applied to the low refractive index layer preferably have an average particle size of 3 to 100 nm. The average particle diameter of primary particles of silicon dioxide dispersed in a primary particle state (particle diameter in a dispersion state before coating) is more preferably 3 to 50 nm, and more preferably 3 to 40 nm. Further preferred is 3 to 20 nm, most preferred is 4 to 10 nm. Moreover, as an average particle diameter of secondary particle | grains, it is preferable from a viewpoint with few hazes and excellent visible light transmittance | permeability that it is 30 nm or less.

  The average particle size of the metal oxide fine particles applied to the low refractive index layer is determined by observing the particle itself or particles appearing on the cross section or surface of the refractive index layer with an electron microscope and measuring the particle size of 1000 arbitrary particles. The simple average value (number average) is obtained. Here, the particle size of each particle is represented by a diameter assuming a circle equal to the projected area.

  The colloidal silica used in the present invention is obtained by heating and aging a silica sol obtained by metathesis with an acid of sodium silicate or the like and passing through an ion exchange resin layer. For example, JP-A-57-14091 JP, 60-219083, JP 60-219084, JP 61-20792, JP 61-188183, JP 63-17807, JP 4-194 No. 93284, JP-A-5-278324, JP-A-6-92011, JP-A-6-183134, JP-A-6-297830, JP-A-7-81214, JP-A-7-101142 Also described in Japanese Patent Laid-Open No. 7-179029, Japanese Patent Laid-Open No. 7-137431, and International Publication No. 94/26530 It is.

  Such colloidal silica may be a synthetic product or a commercial product. The surface of the colloidal silica may be cation-modified, or may be treated with Al, Ca, Mg, Ba or the like.

[Binder resin]
In the thermochromic layer according to the present invention or the dielectric layers having different refractive indexes, it is preferable that vanadium dioxide-containing particles and metal oxide particles are contained in the binder resin.

  Examples of the binder resin applicable to the present invention include a water-soluble binder resin and a solvent-based binder, and are not particularly limited, but among them, a water-soluble binder resin is preferable.

<Water-soluble binder resin>
The water-soluble binder resin is a resin that dissolves or disperses 1.0 g or more with respect to 100 g of water at 25 ° C. In addition, a resin that is dissolved in hot water and similarly dissolved at 25 ° C. is also defined as a water-soluble binder resin in the present invention.

  Examples of the water-soluble binder resin include gelatins, graft polymers of gelatin and other polymers, proteins such as albumin and casein, celluloses, sodium alginate, cellulose sulfate, dextrin, dextran, dextran sulfate, and other sugars. Naturally derived materials such as derivatives and thickening polysaccharides, polyvinyl alcohols, polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic ester Copolymers, acrylic resins such as acrylic acid-acrylic acid ester copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α -Methylstyrene- Styrene acrylic acid resin such as crylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer, styrene-sodium styrenesulfonate copolymer, styrene-2-hydroxyethyl acrylate copolymer, Styrene-2-hydroxyethyl acrylate-potassium styrene sulfonate copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer Vinyl acetate copolymers such as vinyl acetate-maleic acid ester copolymer, vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic acid copolymer, and salts thereof.

  Among them, a polymer containing 50 mol% or more of repeating unit components having a hydroxy group, which has a high affinity with vanadium dioxide-containing particles and has a high effect of preventing particle aggregation even during drying of film formation, is preferable. Examples thereof include celluloses, polyvinyl alcohols, and acrylic resins having a hydroxy group. Among them, polyvinyl alcohols and celluloses can be most preferably used.

  Moreover, resin which has an amide group can also be used as binder resin.

  Examples of the binder resin having an amide group include polyvinyl acetamide, polyacrylamide and a monomer having an amide group, and among them, polyvinyl acetamide is preferable. Those copolymerized with other types of monomers can also be used, and it is also possible to copolymerize with monomers such as acrylic acid and polyvinyl alcohol.

  The molecular weights of polyvinylacetamide and polyacrylamide are preferably in the range of 100,000 to 1,000,000, since higher molecular weights have better film elongation and physical properties at break and higher resistance to blowing during drying. As a suitable example, GE191-103 (made by Showa Denko KK) is mentioned.

  The monomer having an amide group can be used without particular limitation as long as it contains an amide group. Examples thereof include N-vinylacetamide, Nn-butoxymethylacrylamide, N-isobutoxymethylacrylamide, N- Methoxymethylacrylamide, Nt-butylacrylamide, N, N′-methylenebisacrylamide, N, N′-methylenebisacrylamide, N-methoxymethylmethacrylamide, Nt-butylacrylamidesulfonic acid, Nt-butyl Examples include acrylamide sulfonic acid.

[Other additives for dielectric multilayer units]
Various additives that can be applied to the dielectric multilayer unit according to the present invention as long as the effects of the present invention are not impaired are listed below. For example, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, JP-A-62-261476, JP-A-57-74192, JP-A-57-87989 , JP-A-60-72785, JP-A-61-146591, JP-A-1-95091, JP-A-3-13376, etc. Nonionic surfactants, JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, JP-A-4-219266 Fluorescent brighteners, sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and other pH adjusters, antifoaming agents, diethylene glycol Lubricants such as coal, antiseptics, antifungal agents, antistatic agents, matting agents, heat stabilizers, antioxidants, flame retardants, crystal nucleating agents, inorganic particles, organic particles, viscosity reducing agents, lubricants, infrared absorbers And various other known additives.

(Method for forming dielectric multilayer unit)
When the dielectric multilayer unit according to the present invention is formed using an aqueous coating solution containing vanadium dioxide-containing particles or metal oxide particles and a binder, a wet coating method can be applied. The method is not particularly limited, and for example, a roller coating method, a rod bar coating method, an air knife coating method, a spray coating method, a slide curtain coating method, or US Pat. No. 2,761,419, US Pat. No. 2,761791 And a slide hopper coating method and an extrusion coating method described in the above. In addition, as a method of applying a plurality of layers in a multilayer manner, a sequential multilayer application method or a simultaneous multilayer application method may be used.

  When the dielectric multilayer unit according to the present invention is formed of a single material of vanadium dioxide or metal oxide, a dry forming method is suitable, and a vacuum film forming method shown below can be applied.

1) Physical vapor deposition (PVD): resistance heating vacuum deposition, electron beam heating vacuum deposition, ion plating, ion beam assisted vacuum deposition, sputtering, etc.
2) Chemical vapor deposition (CVD): plasma CVD, thermal CVD, metal organic CVD, photo-CVD, etc. can be mentioned.

  Sputtering methods applicable to the present invention include bipolar sputtering, magnetron sputtering, DC sputtering, DC pulse sputtering, RF (radio frequency) sputtering, dual magnetron sputtering, reactive sputtering, and ion beam sputtering. A known sputtering method such as a bias sputtering method and a facing target sputtering method can be used as appropriate. Specific examples of commercially available sputtering equipment include magnetron sputtering equipment manufactured by Osaka Vacuum Co., Ltd., various sputtering equipment manufactured by ULVAC (for example, multi-chamber type sputtering equipment ENTRON-EX W300), Anelva L-430S-FHS sputtering equipment, and the like. Can be used.

[Base material]
The base material (transparent base material) applicable to the present invention is not particularly limited as long as it is transparent, and examples thereof include glass, quartz, and a transparent resin film. From the viewpoint of process suitability, it is preferably a transparent resin film.

  In the present invention, “transparent” means that the average light transmittance in the visible light region is 50% or more, preferably 60% or more, more preferably 70% or more, and particularly preferably 80% or more. is there.

  The thickness of the 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 substrate is 30 μm or more, wrinkles and the like are less likely to occur during handling, and if it is 200 μm or less, for example, when making a laminated glass, follow the curved surface of the glass when bonded to the glass substrate. Sexuality improves.

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

  The base material preferably has a thermal shrinkage within the range of 0.1 to 3.0% at a temperature of 150 ° C. from the viewpoint of preventing wrinkling and cracking of the thermochromic film. More preferably, it is within the range of 0.0%.

  The substrate applicable to the thermochromic film of the present invention is not particularly limited as long as it is transparent, but various resin films are preferably used. For example, polyolefin films (for example, polyethylene, polypropylene, etc.) Polyester films (for example, polyethylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride films, triacetyl cellulose films, and the like can be used, and polyester films and triacetyl cellulose films are preferred.

  The polyester film (hereinafter simply referred to as “polyester”) is not particularly limited, but includes polyesters mainly composed of polyethylene terephthalate and polyethylene naphthalate, terephthalic acid and 2,6-naphthalenedicarboxylic acid, Polyesters composed mainly of a copolymerized polyester composed of ethylene glycol and a mixture of two or more of these polyesters are preferred.

  When using a transparent resin film as a substrate, in order to facilitate handling, particles may be contained within a range that does not impair transparency. Examples of particles used in the present invention include inorganic particles such as calcium carbonate, calcium phosphate, silica, kaolin, talc, titanium dioxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide, and crosslinked polymers. Examples thereof include organic particles such as particles and calcium oxalate.

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

  The transparent resin film is preferably coated with the undercoat layer coating solution in-line on one or both sides during the film formation process. In the present invention, undercoating during the film forming process is referred to as in-line undercoating.

[Other component layers]
(Clear hard coat layer)
The thermochromic film of the present invention may be provided with a clear hard coat layer (also referred to as HC layer) in order to improve the durability of the film.

  As a hard coat material for the clear hard coat layer, an inorganic material typified by polysiloxane, an active energy ray curable resin, or the like can be used.

  Inorganic materials require moisture curing (room temperature to warming), and it is preferable to use an active energy ray-curable resin from the viewpoints of curing temperature, curing time, and cost. The active energy ray resin refers to a resin that is cured through a crosslinking reaction or the like by irradiation with active rays such as ultraviolet rays or electron beams.

  As the active energy ray curable resin, a component containing a monomer having an ethylenically unsaturated double bond is preferably used, and the active energy ray curable resin layer is cured by irradiation with an active ray such as an ultraviolet ray or an electron beam. It is formed. Typical examples of the active energy ray curable resin include an ultraviolet curable resin and an electron beam curable resin, and a resin curable by ultraviolet irradiation is preferable.

  Examples of the ultraviolet curable resin include an ultraviolet curable acrylate resin, an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, and an ultraviolet curable resin. A type epoxy resin or the like is preferably used. Of these, ultraviolet curable acrylate resins are preferred.

  The UV curable urethane acrylate resin generally contains 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter referred to as acrylate) in addition to a product obtained by reacting a polyester polyol with an isocyanate monomer or a prepolymer. It can be easily obtained by reacting an acrylate monomer having a hydroxy group such as 2-hydroxypropyl acrylate. For example, a mixture of 100 parts of Unidic 17-806 (manufactured by DIC Corporation) and 1 part of Coronate L (manufactured by Tosoh Corporation) described in JP-A-59-151110 is preferably used.

  The UV curable polyester acrylate resin can be easily obtained by reacting a monomer such as 2-hydroxyethyl acrylate, glycidyl acrylate, or acrylic acid with a hydroxyl group or a carboxy group at the end of the polyester. Sho 59-151112).

  The ultraviolet curable epoxy acrylate resin is obtained by reacting a terminal hydroxyl group of an epoxy resin with a monomer such as acrylic acid, acrylic acid chloride, or glycidyl acrylate.

  Examples of ultraviolet curable polyol acrylate resins include ethylene glycol (meth) acrylate, polyethylene glycol di (meth) acrylate, glycerin tri (meth) acrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, and dipenta. Examples include erythritol pentaacrylate, dipentaerythritol hexaacrylate, and alkyl-modified dipentaerythritol pentaacrylate.

《Thermochromic Complex》
As a use of the thermochromic film of this invention, it can be used as a thermochromic composite body provided with the thermochromic film as a component. For example, a laminated glass can be constituted by being sandwiched between a pair of glass constituent members, and this laminated glass can be used for automobiles, railway vehicles, aircraft, ships, buildings, and the like. Laminated glass can be used for other purposes. The laminated glass is preferably laminated glass for buildings or vehicles. The laminated glass can be used for an automobile windshield, side glass, rear glass, roof glass, or the like.

  Examples of the glass member include inorganic glass and organic glass (resin glazing). Examples of the inorganic glass include float plate glass, heat ray absorbing plate glass, polished plate glass, mold plate glass, netted plate glass, lined plate glass, and colored glass such as green glass. The organic glass is a synthetic resin glass substituted for inorganic glass. Examples of the organic glass (resin glazing) include a polycarbonate plate and a poly (meth) acrylic resin plate. Examples of the poly (meth) acrylic resin plate include a polymethyl (meth) acrylate plate. In the present invention, inorganic glass is preferred from the viewpoint of safety when it is damaged by an external impact.

  Further, the present invention can be applied to other than glass, and it can be a thermochromic composite composed of a thermochromic film support including glass and a thermochromic film.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.

《Preparation of thermochromic film》
Thermochromic films 1 to 18 were produced as follows.

[Preparation of Thermochromic Film 1]
Dielectric multilayer unit 1 (Configuration 1) composed of 5 layers on a transparent base material of a polyethylene terephthalate film (abbreviation: PET film, Toray U40, double-sided adhesive layer) having a thickness of 50 μm according to the following method Was formed by the sputtering method, and the thermochromic film 1 was produced.

(Formation of dielectric multilayer unit 1)
<First layer: Formation of low refractive index layer 1-1 (layer thickness: 70 nm)>
Using an Anelva L-430S-FHS sputtering apparatus, Ar 20 sccm, O ₂ 0 sccm, sputtering pressure 0.25 Pa, at room temperature (25 ° C.), at a formation rate of 0.06 nm / second, and a layer thickness of 70 nm. The aluminum oxide (purity 99.5%, diameter 50 mm, thickness 5 mm) was DC pulse sputtered and composed of 70 nm thick aluminum oxide (Al ₂ O ₃ ) on the PET film, with a refractive index of 1.62 The low refractive index layer 1-1 was formed.

  In addition, the refractive index of each layer forms the target structural layer on the same formation conditions as the above, and produces the sample for refractive index measurement. Next, using a spectrophotometer U-4100 (manufactured by Shimadzu Corporation), the regular reflectance at an incident angle of 5 ° with respect to the normal of the reflecting surface is measured at a wavelength of 560 nm. Next, the refractive index was measured using thin film calculation software “Essential Macrode” manufactured by Sigma Koki Co., Ltd.

  The refractive index of each layer shown below was also measured by the same method.

<Second layer: Formation of vanadium dioxide layer 1-1 (layer thickness: 50 nm)>
In the formation of the first layer, a thickness was similarly formed on the aluminum oxide (Al ₂ O ₃ ) of the PET film except that the target was changed to vanadium dioxide (purity 99.5%, diameter 50 mm, thickness 5 mm). A vanadium dioxide layer 1-1, which is a second layer made of vanadium dioxide having a thickness of 50 nm and having a refractive index of 2.80, was formed.

<Third layer: Formation of low refractive index layer 1-2 (layer thickness: 70 nm)>
Similarly to the first layer, a third low-refractive index layer 1-2 made of aluminum oxide (Al ₂ O ₃ ) having a thickness of 70 nm and having a refractive index of 1.62 was formed.

<Fourth layer: Formation of vanadium dioxide layer 1-2 (layer thickness: 50 nm)>
Similarly to the second layer, a vanadium dioxide layer 1-2, which is a fourth layer made of vanadium dioxide having a thickness of 50 nm and having a refractive index of 2.80, was formed.

<Fifth layer: Formation of low refractive index layer 1-3 (layer thickness: 70 nm)>
Similarly to the first layer, a fourth layer (low refractive index layer 1-3) made of aluminum oxide (Al ₂ O ₃ ) having a thickness of 70 nm and having a refractive index of 1.62 is formed. The thermochromic film 1 was produced by forming the dielectric multilayer unit 1 (configuration 1) composed of five layers by sputtering.

  The configuration of the dielectric multilayer unit 1 of the thermochromic film 1 is a low refractive index layer 1-1 (layer thickness: 70 nm) / vanadium dioxide layer 1-1 from above the PET as shown in the layer thickness configurations of Tables I and II. Total 5 of (layer thickness: 50 nm) / low refractive index layer 1-2 (layer thickness: 70 nm) / vanadium dioxide layer 1-2 (layer thickness: 50 nm) / low refractive index layer 1-3 (layer thickness: 70 nm) It is a layer structure.

[Preparation of thermochromic film 2]
In the production of the thermochromic film 1, the material for forming the low refractive index layer was changed to silicon dioxide (SiO ₂ ), and the layer thickness of each constituent layer was changed similarly to the conditions described in Table I. A dielectric multilayer unit 2 (Configuration 2) composed of a total of five layers was formed to produce a thermochromic film 2.

[Preparation of thermochromic film 3]
In the production of the thermochromic film 2, a low refractive index layer (SiO ₂ layer, first layer, third layer, fifth layer, seventh layer, ninth layer, eleventh layer) and vanadium dioxide layer (second layer) , 4th layer, 6th layer, 8th layer, 10th layer) are alternately laminated, and dielectric multilayer unit 3 (configuration 3) having the layer thickness configuration 3 described in Table I and Table II is sputtered. A thermochromic film 3 was produced by the method.

[Preparation of thermochromic film 4]
(Preparation of vanadium dioxide-containing particle aqueous dispersion 1)
Using a flow reactor (101) having the hydrothermal reaction section (116) shown in FIG. 9, a dispersion containing vanadium dioxide-containing particles was prepared according to the following method.

First, 19.0 g of vanadium oxide sulfate (IV) (VOSO ₄ ) is dissolved in ion exchange water (dissolved oxygen amount: 8.1 mg / L) to 300 mL in a raw material liquid container (105), and this liquid is stirred. Then, 68 mL of a 3.0 mol / L NH ₃ aqueous solution was added as an alkali to prepare a raw material liquid 1 having a pH of 8.0 (liquid temperature: 25 ° C.).

  On the other hand, ion exchange water (dissolved oxygen amount: 8.1 mg / L) was stored as the raw material liquid 2 in the raw material liquid container (102).

  The raw material liquid 1 containing vanadium oxide oxide (IV) and alkali is fed from the raw material liquid container (105) through the flow path (106) by the pump (107), and heated by the heating medium (115) at 25 ° C. and 30 MPa. The pressure was applied to satisfy the following conditions.

  On the other hand, the ion exchange water as the raw material liquid 2 is fed from the raw material liquid container (102) through the flow path (103) by the pump (104), and is heated by the heating medium (113) at 440 ° C. and 30 MPa. Supercritical water was obtained by heating and pressing.

Next, the raw material liquid 1 containing vanadium oxide (IV) oxide and alkali and the raw material liquid 2 that is supercritical water at the confluence point MP, under the condition that the raw material liquid 1: the raw material liquid 2 = 1: 4 as a volume ratio. By mixing, a reaction solution 1 was prepared and fed to the hydrothermal reaction section (116). In the hydrothermal reaction part (116), the reaction liquid 1 was sent to the heating part piping (117) arrange | positioned in the heating medium (114). As hydrothermal reaction conditions in the heating pipe section (117), the treatment time (passage time) was 2 seconds under the conditions of 400 ° C. and 30 MPa, and vanadium dioxide (VO ₂ ) -containing particles were formed. Subsequently, the reaction liquid 1 was cooled in the cooling part (108), and the dispersion liquid containing vanadium dioxide containing particle | grains and water was prepared.

  After the reaction, the obtained product is washed using ultrafiltration, and dispersed with a super apex mill manufactured by Hiroshima Metal & Machinery Co., Ltd. using zirconia beads having a particle size of 30 μm for 1 hour, and the particle concentration of vanadium dioxide-containing particles A 3.0% by mass aqueous dispersion 1 was prepared. A particle size measurement sample was prepared by mixing the aqueous dispersion 1 of vanadium dioxide-containing particles with water so that the concentration was 0.01% by mass. The number average particle diameter (nm) of the sample for particle size measurement was measured by a dynamic light scattering analyzer (Zetasizer Nano S) method.

(Production of thermochromic film)
<Preparation of coating liquid L1 for forming a low refractive index layer>
Each constituent material described below was sequentially added at 45 ° C.

Colloidal silica (10% by mass, manufactured by Nissan Chemical Industries Co., Ltd .; Snowtex OXS) 300 parts Boric acid aqueous solution (3% by mass) 50 parts Water 55 parts Polyvinyl alcohol (4% by mass, JP-45, manufactured by Nihon Ventures and Poval, Polymerization degree 4500, saponification degree 88 mol%) 750 parts Surfactant (5% by mass, Softazoline LSB-R, manufactured by Kawaken Fine Chemical Co., Ltd.) 3 parts Finally, it is finished to 1500 parts with pure water and the solid content is 4% by mass A coating solution L1 for a low refractive index layer was prepared.

  The solid content concentration of silicon dioxide (colloidal silica) with respect to the total solid content concentration of the coating liquid L1 for the low refractive index layer is 50% by mass.

<Preparation of coating solution S1 for vanadium dioxide layer formation>
The following constituent materials are mixed so as to have the following solid content ratio, and finally, the solid content is 4% by mass using water as a solvent to form a coating solution S1 for forming a vanadium dioxide layer (thermochromic layer). Was prepared. In addition, it prepared so that it might become 35 mass% as solid content concentration of vanadium dioxide in a vanadium dioxide layer. The composition ratio of the solid component is shown below. Vanadium dioxide-containing particle aqueous dispersion 1 (VO ₂ concentration: 3.0% by mass) 35% by mass
Poly-N-vinylacetamide GE191-053 (manufactured by Showa Denko) 50% by mass
Cysteine (Peptide Institute) 5% by mass
Olga Chicks TC-400 (Matsumoto Fine Chemical Co., titanate coupling agent) 10% by mass
<Formation of Dielectric Multilayer Unit 4 (Configuration 4)>
On the transparent substrate of a polyethylene terephthalate film (abbreviation: PET film, Toray U40, double-sided easy-adhesion layer) having a thickness of 50 μm, the above-prepared coating solution L1 for forming a low refractive index layer and coating solution for forming a vanadium dioxide layer are prepared. Using S1 and using a slide hopper type coater capable of simultaneous 31-layer coating, the supply amount of the coating solution for forming each layer is appropriately adjusted so that each layer thickness after drying has the configuration described in Table I and Table II. Adjustment was performed, and a dielectric multilayer unit 4 (configuration 4) composed of 11 layers was applied and dried to produce a thermochromic film 4.

  The configuration of the dielectric multilayer unit 4 (Configuration 4) after drying the thermochromic film 4 is as follows.

  The configuration of the dielectric multilayer unit 4 of the thermochromic film 4 is a low refractive index layer 4-1 (layer thickness: 50 nm) / vanadium dioxide layer 4-1 from the PET as shown in the layer thickness configurations of Table I and Table II. (Layer thickness: 50 nm) / Low refractive index layer 4-2 (Layer thickness: 111 nm) / Vanadium dioxide layer 4-2 (Layer thickness: 45 nm) / Low refractive index layer 4-3 (Layer thickness: 132 nm) / Vanadium dioxide Layer 4-3 (layer thickness: 50 nm) / low refractive index layer 4-4 (layer thickness: 150 nm) / vanadium dioxide layer 4-4 (layer thickness: 50 nm) / low refractive index layer 4-5 (layer thickness: 48 nm) ) / Vanadium dioxide layer 4-5 (layer thickness: 98 nm) / low refractive index layer 4-6 (layer thickness: 117 nm). The refractive index of each vanadium dioxide layer (vanadium dioxide concentration: 35% by mass) is 2.02, the refractive index of each low refractive index layer is 1.48, and the refractive index difference between the two layers is 0.00. 54.

[Preparation of thermochromic film 5]
In the production of the thermochromic film 4, the concentration of vanadium dioxide in the vanadium dioxide layer was changed to 30% by mass, and the layer thickness of each constituent layer was changed to the configuration described in Table I and Table II in the same manner. The thermochromic film 5 was produced.

  The refractive index of each vanadium dioxide layer (vanadium dioxide concentration: 30% by mass) constituting the thermochromic film 5 is 1.94, the refractive index of each low refractive index layer is 1.48, and the refractive index between the two layers. The rate difference is 0.46.

[Preparation of thermochromic films 6-11]
In the production of the thermochromic film 4, the vanadium dioxide concentration in the vanadium dioxide layer, the thickness and number of each layer of the dielectric multilayer unit, and the refractive index difference between the two layers were changed to the conditions described in Table I and Table II. Made thermochromic films 6 to 11 in the same manner.

[Preparation of Thermochromic Film 12]
In the production of the thermochromic film 6, a thermochromic film 12 was produced in the same manner except that the metal oxide particles constituting the low refractive index layer were changed from silicon dioxide to aluminum oxide. The refractive index of the vanadium dioxide layer (vanadium dioxide concentration: 10 mass%) in the thermochromic film 12 is 1.63, the refractive index of each low refractive index layer is 1.58, and the refractive index difference between the two layers is , 0.05.

[Preparation of Thermochromic Film 13]
In the production of the thermochromic film 6, the composition of the vanadium dioxide layer forming coating solution and the low refractive index layer forming coating solution is replaced with an aqueous coating solution, and a solvent-based multilayer coating method using a solvent-based coating solution shown below. Thus, a thermochromic film 13 was produced in the same manner except that the dielectric multilayer unit was formed.

(Vadium dioxide layer forming coating solution)
<Preparation of organic solvent dispersion of vanadium dioxide particles>
74.9 g of vanadium dioxide particles prepared by the above hydrothermal reaction are mixed with 425 mL of methyl isobutyl ketone, 30.0 g of a dispersing agent BYK-399 (manufactured by Big Chemie), and 45.0 g of trioctylamine (manufactured by Wako Pure Chemical Industries). Then, 200 g of 30 μm zirconia beads for bead mill were used, and pulverization was performed using Apex mill (manufactured by Hiroshima Metal & Machinery Co., Ltd.) to prepare a vanadium dioxide particle organic solvent dispersion.

<Preparation of solvent-based vanadium dioxide layer coating solution>
The following constituent materials were mixed so as to have the following ratios, and finally, using methyl isobutyl ketone as a solvent, the solid content of vanadium dioxide particles was adjusted to 10% by mass. The VO ₂ amount of the VO ₂ particle organic solvent-based dispersion showing the composition ratio of the solid component is 10% by mass.
Aronix M-305 (Toagosei Co., Ltd.) 72% by mass
Irgacure 184 (BASF Japan) 3% by mass
Surflon S-242 (manufactured by AGC Seimi Chemical) 0.1% by mass
Cysteamine (manufactured by Tokyo Chemical Industry Co., Ltd.) 5% by mass
Olga Chicks TC-400 (Matsumoto Fine Chemical Co., Ltd.) 10% by mass
(Coating liquid for forming low refractive index layer)
<Preparation of silicon dioxide particle organic solvent dispersion>
72.5 g of silicon dioxide particles are mixed with 425 mL of methyl isobutyl ketone, 30.0 g of a dispersing agent BYK-399 (manufactured by Big Chemie) and 45.0 g of trioctylamine (manufactured by Wako Pure Chemical Industries) are added, and 30 μm for a bead mill. 200 g of the above zirconia beads were used and pulverized using an Apex mill (manufactured by Hiroshima Metal & Machinery Co., Ltd.) to prepare a silicon dioxide particle organic solvent dispersion.

<Preparation of solvent-based low refractive index layer coating solution>
The following constituent materials were mixed so as to have the following ratios, and finally, using methyl isobutyl ketone as a solvent, the solid content of silicon dioxide particles with respect to the total solid content was adjusted to 50% by mass. The silicon dioxide content of the organic solvent-based dispersion of silicon dioxide particles showing the composition ratio of the solid component is 50% by mass.
Aronix M-305 (manufactured by Toagosei Co., Ltd.) 47% by mass
Irgacure 184 (BASF Japan) 3% by mass
Surflon S-242 (manufactured by AGC Seimi Chemical) 0.1% by mass
(Formation of dielectric multilayer unit 13)
On the transparent base material of a polyethylene terephthalate film (abbreviation: PET film, Toray U40, double-sided easy-adhesion layer) having a thickness of 50 μm, the solvent-based low refractive index layer-forming coating solution and the solvent-based vanadium dioxide layer are formed. Supply amount of coating solution for forming each layer so that the thickness of each layer after drying is as shown in Table I and Table II, using a slide hopper type coater capable of simultaneous 11-layer coating. Was appropriately adjusted, and a dielectric multilayer unit 13 (configuration 13) composed of 11 layers was applied and dried to prepare a thermochromic film 13.

[Preparation of Thermochromic Film 14]
<Preparation of coating solution for vanadium dioxide layer formation>
The following constituent materials are mixed so as to have the following solid content ratio, and finally the solid content becomes 4% by mass using water as a solvent, and a coating solution for forming a vanadium dioxide layer (thermochromic layer) is prepared. Prepared. The solid content concentration of vanadium dioxide with respect to the total solid content of the coating liquid for forming a vanadium dioxide layer is 3% by mass. The composition ratio of the solid component is shown below. Vanadium dioxide-containing particle aqueous dispersion 1 (VO ₂ concentration: 3.0% by mass) 3% by mass
Poly-N-vinylacetamide GE191-053 (manufactured by Showa Denko KK) 82% by mass
Cysteine (Peptide Institute) 5% by mass
Olga Chicks TC-400 (Matsumoto Fine Chemical Co., titanate coupling agent) 10% by mass
<Preparation of coating solution for forming low refractive index layer>
The following constituent materials were mixed so as to have the following solid content ratio, and finally, a coating solution for forming a low refractive index layer was prepared using water as a solvent so that the solid content was 4% by mass. The solid content concentration of silicon dioxide with respect to the total solid content of the coating solution for forming a low refractive index layer is 50% by mass.

Colloidal silica (10% by mass, manufactured by Nissan Chemical Industries Co., Ltd .; Snowtex OXS) 300 parts Boric acid aqueous solution (3% by mass) 50 parts Water 55 parts Polyvinyl alcohol (4% by mass, JP-45, manufactured by Nihon Ventures and Poval, Polymerization degree 4500, saponification degree 88 mol%) 750 parts Surfactant (5% by mass, Softazoline LSB-R, manufactured by Kawaken Fine Chemicals Co., Ltd.) 3 parts Finally, it is finished to 1500 parts with pure water, and the solid content is 4% by mass. A coating solution for a low refractive index layer was prepared.

<Preparation of coating solution for forming a high refractive index layer>
The following constituent materials were mixed so as to have the following solid content ratio, and finally a coating solution for forming a high refractive index layer was prepared using water as a solvent so that the solid content was 4% by mass. The solid content concentration of zirconium oxide with respect to the total solid content of the coating solution for forming a high refractive index layer is 12% by mass.

Zirconium oxide dispersion (10% by mass) 40 parts by mass Boric acid aqueous solution (3% by mass) 50 parts Water 55 parts Polyvinyl alcohol (4% by mass, JP-45, manufactured by Nihon Acetate / Poval, polymerization degree 4500, saponification degree 88 mol) %) 750 parts Surfactant (5% by mass, Softazoline LSB-R, manufactured by Kawaken Fine Chemicals Co., Ltd.) 3 parts Finally, it was finished to 1500 parts with pure water to prepare a coating solution for a high refractive index layer.

  On the transparent substrate of a polyethylene terephthalate film (abbreviation: PET film, Toray U40, double-sided adhesive layer) having a thickness of 50 μm, after drying, using the prepared coating solution for forming a vanadium dioxide layer (thermochromic layer) A thermochromic layer was formed under the condition that the layer thickness of 1.40.

  Next, using the prepared coating liquid for forming a low refractive index layer containing silicon dioxide and a coating liquid for forming a high refractive index layer containing zirconium oxide, using a slide hopper type coater capable of simultaneous 11-layer coating, The dielectric multilayer unit 14 (configuration 14) configured with 11 layers is adjusted by appropriately adjusting the supply amount of the coating liquid for forming each layer so that each layer thickness after drying has the configuration described in Table I and Table II. The thermochromic film 14 was produced by applying and drying on the thermochromic layer.

  The configuration of the dielectric multilayer unit 14 (configuration 14) after drying the thermochromic film 14 is as follows.

  The configuration of the dielectric multilayer unit 14 of the thermochromic film 14 is a low refractive index layer 14-1 (layer thickness: 69 nm) / high refraction from above the PET / thermochromic layer as shown in the layer thickness configurations of Tables I and II. Index layer 14-1 (layer thickness: 150 nm) / low refractive index layer 14-2 (layer thickness: 69 nm) / high refractive index layer 14-2 (layer thickness: 150 nm) / low refractive index layer 14-3 (layer thickness) : 84 nm) / high refractive index layer 14-3 (layer thickness: 150 nm) / low refractive index layer 14-4 (layer thickness: 59 nm) / high refractive index layer 14-4 (layer thickness: 150 nm) / low refractive index layer The total number of layers is 11-5: 14-5 (layer thickness: 78 nm) / high refractive index layer 14-5 (layer thickness: 150 nm) / low refractive index layer 14-6 (layer thickness: 150 nm). The refractive index of the low refractive index layer is 1.48, the refractive index of the high refractive index layer is 1.60, and the refractive index difference between the two layers is 0.12.

[Preparation of Thermochromic Film 15]
<Preparation of coating solution for vanadium dioxide layer formation>
The following constituent materials are mixed so as to have the following solid content ratio, and finally the solid content becomes 4% by mass using water as a solvent, and a coating solution for forming a vanadium dioxide layer (thermochromic layer) is prepared. Prepared. The solid content concentration of vanadium dioxide with respect to the total solid content of the coating liquid for forming a vanadium dioxide layer is 3% by mass. The composition ratio of the solid component is shown below.

Vanadium dioxide-containing particle aqueous dispersion 1 (VO ₂ concentration: 3.0% by mass) 3% by mass
Poly-N-vinylacetamide GE191-053 (manufactured by Showa Denko KK) 82% by mass
Cysteine (Peptide Institute) 5% by mass
Olga Chicks TC-400 (Matsumoto Fine Chemical Co., titanate coupling agent) 10% by mass
<Formation of thermochromic layer>
On the transparent substrate of a polyethylene terephthalate film (abbreviation: PET film, Toray U40, double-sided adhesive layer) having a thickness of 50 μm, after drying, using the prepared coating solution for forming a vanadium dioxide layer (thermochromic layer) A thermochromic layer (refractive index: 1.52) was formed under the condition that the layer thickness was 1.10 μm, and a thermochromic film 15 was produced.

[Preparation of thermochromic film 16]
In the production of the thermochromic film 15, a thermochromic film 16 was produced in the same manner except that a clear hard coat layer containing the pigment described below was further provided on the thermochromic layer.

(Formation of clear hard coat layer containing pigment)
Add 0.1% by mass of neodymium oxide and 1ppm cobalt oxide as pigments, pentaerythritol triacrylate (Daicel Cytec), methyl ethyl ketone as solvent, and fluorine-based surfactant (Megafax manufactured by DIC) F-552, a fluorosurfactant) is added in an amount of 0.1% by mass, and a hard coat layer coating solution is prepared so that the total solid content is 30 parts by mass, and this is applied to the thermochromic film 15. The film was coated on the layer under the condition that the film thickness after drying was 2.0 μm, dried at a drying section temperature of 90 ° C., and then the illuminance of the irradiated part was 100 mW / cm ² using an ultraviolet lamp, and the irradiation amount was 0.5 J / The clear hard coat layer was cured as cm ² to form a clear hard coat layer, and a thermochromic film 16 was produced.

[Preparation of Thermochromic Film 17]
In the preparation of the thermochromic film 2, a metal oxide target to form a low refractive index layer, except for the use of TiO ₂ in place of the SiO ₂ in the same manner, to prepare a thermochromic film 17. The refractive index difference between the two layers is 0.03.

[Preparation of thermochromic film 18]
In the production of the thermochromic film 2, the configuration of the dielectric multilayer unit was changed to a three-layer configuration of a low refractive index layer: 50 nm / vanadium dioxide-containing layer: 200 nm / low refractive index layer: 50 nm. A thermochromic film 18 was produced.

  The details of the composition of the thermochromic film produced above are shown in Table I.

  Details of the configuration of each dielectric multilayer unit are shown in Table II.

<Measurement and evaluation of thermochromic film>
About each produced thermochromic film, the measurement of characteristic value and each evaluation were performed.

[Measurement of maximum reflection peak value in visible light range]
About each thermochromic film, the reflection spectrum to 250-2500 nm as a wavelength range was measured using the spectrophotometer V-670 (made by JASCO Corporation).

  The maximum reflection peak value (nm) in the wavelength range of 380 to 780 nm of the obtained reflection spectrum was determined.

[Measurement of reflectance difference ΔD in visible light and near infrared region]
About each thermochromic film, the reflection spectrum to 250-2500 nm as a wavelength range was measured using the spectrophotometer V-670 (made by JASCO Corporation).

  Next, the difference ΔD (%) between the reflectance at the maximum reflection peak value in the visible light region and the reflectance at a wavelength of 1000 nm was determined.

[Evaluation of heat cracking resistance]
Each thermochromic film produced above was attached to a glass plate having a width of 200 mm, a length of 300 mm, and a thickness of 1.5 mm with an acrylic adhesive to obtain a sample for thermal crack evaluation.

  Subsequently, a box (height 150 mm, width 240 mm, length 340 mm) made of expanded polystyrene having a thickness of 30 mm and having an open top surface and a bottom surface is prepared, and the prepared sample for evaluation is placed in the opening of each box. Then, while measuring the temperature of the glass sample surface (film surface side) inside the box with a thermocouple, sunlight was exposed on a clear day in August. Thereafter, the temperature of the sample surface was observed, and each MAX temperature was measured. Similarly, the surface temperature of the glass plate alone was also measured, and the difference from the surface temperature of the sample was used as a measure of the thermal cracking property. The smaller the temperature difference, the better the resistance to thermal cracking. The determination was in accordance with the following criteria. Up to △ is an acceptable level with no actual harm.

○: Less than 0.5 ° C Δ: 0.5 or more and less than 1.0 ° C ×: 1.0 ° C or more [Color tone evaluation]
For each thermochromic film, a spectrum from 250 to 2500 nm is measured using a spectrophotometer V-670 (manufactured by JASCO Corp.), and the color space represents the lightness L ^* and the color space value a ^*. , B ^* was determined. These characteristic values are a CIE Lab color system, L ^* = 0 is represented by black, L ^* = 100 is represented by white, a ^* is a position of red and green (negative values are green, positive values) Represents red), and b ^* corresponds to the positions of yellow and blue (negative values are blue, positive values are yellow).

[Measurement of ΔTSER (heat insulation performance) and average visible light transmittance]
About each thermochromic film, the difference ((DELTA) TSER) of the heat-shielding performance by a temperature change was measured in accordance with the following method.

  First, for each thermochromic film, light transmittance and light reflectance every 2 nm are measured in a region of 250 nm to 2500 nm using a spectrophotometer (using an integrating sphere, manufactured by Hitachi, Ltd., U-4000 type). did. At that time, the temperature of the thermochromic film was measured at two levels of low temperature (10 ° C.) and high temperature (70 ° C.).

  Next, after obtaining the solar reflectance R (DS) and solar transmittance T (DS) according to the method described in JIS R 3106: 1998, the heat shielding performance at low temperatures and high temperatures calculated from the following formulas. (DELTA) TSER was computed from the following Formula from (total solar energy reflectance: Total Solar Energy Reflectance: TSER).

TSER (%) = ((100−T (DS) −R (DS)) × 0.7143) + R (DS)
ΔTSER (%) = TSER (high temperature)-TSER (low temperature)
Moreover, the average value of the transmittance | permeability in a wavelength range of 380 nm-780 nm was calculated | required, and this was made into the visible light average transmittance | permeability.

[Measurement of haze]
Using NDH7000 (manufactured by Nippon Denshoku Industries Co., Ltd.), light was incident from the dielectric multilayer unit forming surface, and the haze value (initial haze) of the light at that time was measured.

  The results obtained as described above are shown in Table III.

As is clear from the results described in Table III above, the thermochromic film of the present invention is superior to the thermochromic film of the comparative example in terms of heat crack resistance, high reflectance in the visible light sense, and color tone comparison. As shown in the thermochromic films 15 and 18 as examples, the b ^* value is greatly shifted to the positive side, and it is found that the film has good neutrality without yellowing.

  In addition, it was confirmed that the film was a high-quality thermochromic film with a large difference in thermal barrier properties (ΔTSER) with respect to temperature change and a low haze.

1 Thermochromic film 2A, 2B Base material (transparent base material)
3 Thermochromic layer 4 Clear hard coat layer 5 Adhesive layer 6 Pigment-containing clear hard coat layer 7 Low refractive index layer 8 High refractive index layer 101 Flow reactor 102, 105 Raw material liquid container 103, 106, 111, 118 Flow path ( Plumbing)
104, 107, 112 Pump 108 Cooling unit 109, 110 Tank 113, 114, 115 Heating medium 116 Hydrothermal reaction unit 117 Heating unit piping 119 Control valve B Binder resin VO _S Primary particle VO _M Secondary particle C Refrigerant IN Heating medium OUT OUT Heating medium outlet L Heater line length MP Junction point TC Temperature sensor U Dielectric multilayer unit

Claims (11)

A thermochromic film having a thermochromic layer containing vanadium dioxide-containing particles exhibiting thermochromic properties on a substrate,
It has a dielectric multilayer unit composed of two types of layers having different refractive indexes of 0.05 or more, and the total number of constituent layers is at least three.
The layer thickness of a single layer constituting the dielectric multilayer unit is less than 1.0 μm,
And the maximum reflection peak value of the said dielectric multilayer unit exists in a visible light region. The thermochromic film characterized by the above-mentioned.   2. The thermochromic according to claim 1, wherein any one of the two types of layers having a refractive index of 0.05 or more is a thermochromic layer containing vanadium dioxide-containing particles exhibiting the thermochromic property. the film.   The thermochromic film according to claim 1 or 2, wherein the dielectric multilayer unit has a configuration in which the total number of layers is laminated within a range of 5 to 31 layers.   4. The thermo according to claim 1, wherein a difference in refractive index between two kinds of layers having different refractive indexes constituting the dielectric multilayer unit is 0.10 or more. 5. Chromic film.   2. A layer having a refractive index different from that of the thermochromic layer among two layers having different refractive indexes constituting the dielectric multilayer unit is a layer containing silica particles and a binder. The thermochromic film according to any one of claims 1 to 4.   The layer thickness of each constituent layer excluding the uppermost layer and the lowermost layer of the dielectric multilayer unit is in the range of 50 to 150 nm, respectively. Thermochromic film.   The thermochromic film according to any one of claims 1 to 6, wherein the thermochromic layer contains vanadium dioxide-containing particles and a binder.   The thermochromic film according to any one of claims 1 to 7, wherein the vanadium dioxide-containing particle concentration in the thermochromic layer is in the range of 2 to 30% by mass.   The difference between the reflectance at the maximum reflection peak value in the visible light region of the dielectric multilayer unit and the reflectance at 1000 nm is 5.0% or more, and any one of claims 1 to 8 The thermochromic film according to one item.   The thermochromic film according to any one of claims 1 to 9, wherein the thermochromic film has a dielectric multilayer unit having two kinds of layers having different refractive indexes of 0.05 or more and a total number of constituent layers of at least three layers. A method for producing a thermochromic film, comprising producing the thermochromic film.   The method for producing a thermochromic film according to claim 10, wherein the layers constituting the dielectric multilayer unit are formed by a wet coating method.

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