JP6384247B2 - Optical film and optical film manufacturing method - Google Patents

Description

  The present invention relates to an optical film and a method for producing the same. More specifically, the present invention relates to an optical film having thermochromic properties excellent in repeated durability and a method for producing the same.

  In recent years, glass or a film that is bonded to glass that has a high heat insulating property or a heat insulating property that blocks the heat felt by human skin due to the influence of sunlight entering from the vehicle window has been distributed in the market. Recently, with the widespread use of electric vehicles and the like, development of near-infrared light (heat ray) shielding films applied to glass has been actively conducted from the viewpoint of increasing the cooling efficiency in the vehicle.

  By applying the near-infrared light shielding film to the window glass of a vehicle body or a building, it is possible to reduce the load on the cooling equipment such as an air conditioner in the vehicle, which is an effective means for saving energy.

  As such a near-infrared shielding film, an optical film containing a conductor such as ITO (tin-doped indium oxide) as an infrared absorbing substance is disclosed. 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.

  On the other hand, it has a reflective layer stack in which a large number of low refractive index layers and high refractive index layers are alternately stacked, and selectively reflects near infrared light by adjusting the thickness of each refractive index layer. A near-infrared light shielding film has been proposed (see, for example, Patent Document 1).

  The near-infrared light shielding film having such a configuration is preferably used due to its high near-infrared light shielding effect in a low-latitude zone near the equator where the illuminance of sunlight is high. However, in the mid-latitude to high-latitude winter season, there is a problem that incident light is uniformly shielded even when it is desired to capture sunlight as much as possible in the vehicle or in the room.

In order to solve the above-described problems, a method of applying a thermochromic material that controls the optical properties of near-infrared light shielding and transmission by temperature to the near-infrared light shielding film has been studied. A typical material is vanadium dioxide (hereinafter also referred to as “VO ₂ ”). VO ₂ is known to cause a phase transition in a temperature range of around 68 ° C. and exhibit thermochromic properties.

In other words, the optical film using the characteristics of VO ₂ can shield near-infrared light that causes heat at a high temperature, and can exhibit characteristics that transmit near-infrared light at a low temperature. As a result, when the summertime is hot, near-infrared light is shielded to suppress the temperature rise in the room, and when the wintertime is cold, external light energy can be taken in.

As a specific example of VO ₂ having such characteristics, a method of obtaining vanadium dioxide (VO ₂ ) nanoparticles by hydrothermal synthesis from a vanadium compound and hydrazine or a hydrate thereof is disclosed ( For example, see Patent Document 2.) Also, a method of providing a thermochromic film as a laminate in which VO ₂ nanoparticles prepared by the hydrothermal synthesis method are dispersed in a transparent resin to form a VO ₂ dispersed resin layer on a resin substrate (for example, a patent Reference 3) and a method for providing a thermochromic film by a T-die method by mixing VO ₂ nanoparticles doped with molybdenum or the like into a polyester resin are disclosed (for example, see Patent Document 4).

However, since the volume of VO ₂ changes at the time of phase transition, if the phase transition is repeated, the binder resin contained in the thermochromic film is damaged, and cracks and haze increase occur. There is.

International Publication No. 2013/065679 JP2011-178825A JP2013-184091A JP 2004-346260 A

  This invention is made | formed in view of the said problem, The subject is providing the optical film which has the thermochromic property excellent in repeated durability, and its manufacturing method.

  As a result of intensive studies in view of the above problems, the present inventor is an optical film having an optical functional layer containing at least vanadium dioxide-containing fine particles and a binder resin, and the optical functional layer has a glass transition temperature (hereinafter referred to as a glass transition temperature). And at least two types of binder resins having different glass transition temperatures of 65 ° C. or less, and a phase transition. While suppressing the occurrence of damage due to volume change at the time, it was possible to prevent the stickiness of the surface and deterioration of scratch resistance, and in turn, to provide an optical film having thermochromic properties with excellent durability, The present invention has been reached.

  That is, the said subject of this invention is solved by the following means.

1. An optical film having an optical functional layer containing at least vanadium dioxide-containing fine particles and a binder resin,
The optical functional layer contains at least two binder resins having different glass transition temperatures;
An optical film having at least one glass transition temperature of the binder resin of 65 ° C. or lower.

  2. 2. The optical film as set forth in claim 1, wherein at least one glass transition temperature of the binder resin is 75 ° C. or higher.

  3. 3. The optical film according to item 1 or 2, wherein the surface of the vanadium dioxide-containing fine particles is coated with the binder resin having a glass transition temperature of 65 ° C. or lower.

4). A method for producing an optical film comprising a step of forming an optical functional layer containing at least vanadium dioxide-containing fine particles and a binder resin,
In the step,
As the vanadium dioxide-containing fine particles, using vanadium dioxide-containing fine particles prepared by an aqueous synthesis method,
After coating the surface of the vanadium dioxide-containing fine particles with a binder resin having a glass transition temperature of 65 ° C. or less, without passing through a dry state,
An optical functional layer-forming coating solution is prepared by mixing with a binder resin having a glass transition temperature of 75 ° C. or higher, and the optical functional layer-forming coating solution is applied on a transparent substrate and dried to obtain an optical functional layer. Forming an optical film.

  By the above means of the present invention, it is possible to provide an optical film having thermochromic properties excellent in repeated durability and a method for producing the same.

  The expression mechanism / action mechanism that has achieved the above-described object effect of the present invention is not clear, but is presumed as follows.

Since the volume of VO ₂ changes at the time of phase transition, the present inventor said that when the phase transition is repeated, the binder resin contained in the thermochromic film (optical film) is damaged, and cracks and haze increase occur. In order to solve the problem, first, a binder resin having a low glass transition temperature (Tg) was used, and thereby, it was considered to cope with a volume change at the phase transition.
However, VO ₂ causes a phase transition by absorbing light and generating heat, and this phase transition occurs at around 60 ° C. For this reason, when only a binder resin having a glass transition temperature of 60 ° C. or lower is used, there arises a new problem that the surface is sticky, scratch resistance is poor, and it cannot be used.
The present inventor has found that after the trial and error, this newly generated problem can be solved by using at least two types of binders having different glass transition temperatures. In other words, the binder resin having a glass transition temperature of 65 ° C. or lower suppresses the occurrence of damage due to the volume change during the phase transition of VO ₂ , but the glass transition temperature is lower than that of the binder resin having a glass transition temperature of 65 ° C. or lower. It has been found that a binder resin having a high transition temperature can prevent surface stickiness and deterioration of scratch resistance, and thus can provide an optical film having thermochromic properties with excellent repeated durability.

In addition, the present inventor, after coating the VO ₂ particles with a binder resin having a low glass transition temperature and then mixing with a binder resin having a high glass transition temperature further suppresses the occurrence of damage, It has also been found to be preferable because it can prevent stickiness and deterioration of scratch resistance.

Schematic sectional view showing an example of the basic configuration of the optical film of the present invention Schematic sectional view showing another example of the basic configuration of the optical film of the present invention Schematic sectional view showing an example of the layer arrangement of the optical film having the near infrared light shielding layer of the present invention Schematic process drawing showing an example of a solvent replacement processing apparatus applicable to the present invention

  The optical film of the present invention is an optical film having an optical functional layer containing at least vanadium dioxide-containing fine particles and a binder resin, and the optical functional layer contains at least two binder resins having different glass transition temperatures. The glass transition temperature of at least one of the binder resins is 65 ° C. or lower. This feature is a technical feature common to the inventions according to claims 1 to 4.

  As an embodiment of the present invention, from the viewpoint of more manifesting the effect of the present invention, it is preferable that at least one glass transition temperature of the binder resin is 75 ° C. or higher. Since it is possible to prevent the stickiness of the surface and the deterioration of the scratch resistance while suppressing the occurrence of damage due to, it is preferable from the viewpoint of further realizing the object effect of the present invention.

The viewpoint that the surface of the vanadium dioxide-containing fine particles is coated with the binder resin having a glass transition temperature of 65 ° C. or lower can further suppress the occurrence of damage due to the volume change during the phase transition of VO _2. To preferred.

  The method for producing an optical film of the present invention is a method for producing an optical film having a step of forming an optical functional layer containing at least vanadium dioxide-containing fine particles and a binder resin, wherein in the step, the vanadium dioxide-containing fine particles are formed. As described above, the vanadium dioxide-containing fine particles prepared by the water-based synthesis method were used, and the glass transition temperature of the vanadium dioxide-containing fine particles was coated with a binder resin having a glass transition temperature of 65 ° C. or less without passing through a dry state. An optical functional layer forming coating solution is prepared by mixing with a binder resin having a temperature of 75 ° C. or higher, and the optical functional layer forming coating solution is coated on a transparent substrate and dried to form an optical functional layer. It is characterized by.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, "-" shown in the following description is used with the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<< Summary of optical film layer structure >>
The optical film of the present invention is an optical film having an optical functional layer containing at least vanadium dioxide-containing fine particles and a binder resin, and the optical functional layer contains at least two binder resins having different glass transition temperatures. The glass transition temperature of at least one of the binder resins is 65 ° C. or lower.

  A typical configuration example of the optical film of the present invention will be described with reference to the drawings.

  One of the preferable embodiments of the optical film of the present invention is a configuration in which the optical functional layer according to the present invention is formed on a transparent substrate.

  FIG. 1 is a schematic cross-sectional view showing an example of a basic configuration of an optical film having an optical functional layer which is a first embodiment containing vanadium dioxide-containing fine particles and a binder resin defined in the present invention.

An optical film 1 shown in FIG. 1 has a configuration in which an optical functional layer 3 is laminated on a transparent substrate 2. The optical functional layer 3 of the first embodiment is present in a state where vanadium dioxide-containing fine particles are dispersed in the binder resin B1 contained in the optical functional layer according to the present invention. The vanadium dioxide-containing fine particles, constitutes the primary particles VO _S of vanadium dioxide vanadium-containing particles dioxide are present independently, an aggregate of two or more vanadium-containing microparticles dioxide (also referred to as aggregates) there, there is a secondary particle VO _M of vanadium dioxide. In the present invention, an aggregate of two or more vanadium dioxide-containing fine particles is collectively referred to as secondary particles, and is also referred to as secondary particle aggregates or secondary aggregate particles.

In the present invention, the number average particle size by all the particles of the primary particles V0 _S and secondary particles VO _M of vanadium dioxide-containing fine particles in the optical function layer 3 is preferably less than 200 nm.

  The number average particle diameter of the vanadium dioxide-containing fine particles in the optical functional layer can be determined according to the following method.

First, the side surface of the optical functional layer 3 constituting the optical film 1 is trimmed by a microtome to expose a cross section as shown in FIG. Next, the exposed cross section is photographed at 10,000 to 100,000 times using a transmission electron microscope (TEM). The particle size of all the vanadium dioxide-containing fine particles present in a certain region of the photographed cross section is measured. At this time, the vanadium dioxide-containing fine particles to be measured are preferably in the range of 50 to 100 particles. The shot particles, the primary particles are single particles, as shown in FIG. 1, includes a with a two or more particles of the aggregate secondary particles, the particle size of the primary particles VO _S vanadium dioxide Measure the diameter of each independent particle. If it is not spherical, the projected area of the particle is converted into a circle, and its diameter is taken as the particle size. On the other hand, for vanadium dioxide in which two or more particles are aggregated, the projected area of the entire aggregate is obtained, and then the projected area is converted into a circle, and the diameter is taken as the particle size. The number average diameter is obtained for each diameter of the primary particles and secondary particles obtained as described above. Since the cut-out cross-sectional portion has a variation in particle distribution, such measurement was performed for 10 different cross-sectional regions to obtain the whole number-average diameter, which was defined as the number-average particle size (nm).

  Although details of the vanadium dioxide-containing fine particles according to the present invention will be described later, the preferred primary particle diameter is in the range of 10 to 100 nm. Accordingly, the preferred secondary particle size varies depending on the number of aggregated particles, but is roughly in the range of 50 to 500 nm.

  The optical film of the present invention may have a near-infrared light shielding layer having a function of shielding at least a part of light within a wavelength range of 700 to 1000 nm in addition to the optical functional layer according to the present invention. Good.

  Another preferred embodiment of the optical film of the present invention is a hybrid structure in which the optical functional layer also serves as a resin substrate.

FIG. 2 is a schematic cross-sectional view showing another example of the basic configuration of the optical film of the present invention, in which the transparent substrate 2 and the optical functional layer 3 shown in FIG. The binder resin B2 contained in the optical functional layer according to the present invention is used as the resin constituting the hybrid optical functional layer (2 + 3), which is an embodiment of the present invention, and constituting the transparent substrate. during a primary particle VO _S of the vanadium dioxide vanadium dioxide-containing microparticles, it is the secondary particles VO _M of vanadium dioxide-containing fine particles dispersed, to form an optical functional layer having both a transparent substrate in a single layer It is the composition which is.

  FIG. 3 shows an optical film having a near-infrared light shielding layer together with the optical functional layer 3 according to the first embodiment of the present invention on a transparent substrate, the representative layer of which is shown in FIG. It is a schematic sectional drawing which shows arrangement | positioning.

  The optical film 1 shown in FIG. 3A has a configuration in which the optical functional layer 3, the near infrared light shielding layer 4, and the transparent substrate 2 are arranged in this order from the light incident side L.

  The optical film 1 shown in FIG. 3B is an example in which the optical functional layer 3 according to the present invention is disposed between the transparent substrate 2 and the near-infrared light shielding layer 4, and FIG. ) Is an example in which the near-infrared light shielding layer 4 is disposed on the light incident side L of the transparent substrate 2 and the optical functional layer 3 according to the present invention is disposed on the back side of the transparent substrate 2.

  As an optical film of this invention, you may provide various functional layers as needed other than each structure layer demonstrated above.

  The total thickness of the optical film of the present invention is not particularly limited, but is in the range of 10 to 1500 μm, preferably in the range of 20 to 1000 μm, more preferably in the range of 30 to 500 μm, particularly Preferably it exists in the range of 40-300 micrometers.

  As an optical characteristic of the optical film of the present invention, the visible light transmittance measured by JIS R3106 (1998) is preferably 30% or more, more preferably 50% or more, and further preferably 60% or more. is there.

<Each film material>
The optical film of the present invention has an optical functional layer containing at least vanadium dioxide-containing fine particles and a binder resin, and the optical functional layer contains at least two types of binder resins having different glass transition temperatures. At least one glass transition temperature is 65 ° C. or lower.

  Hereinafter, details of the optical functional layer, which is a constituent element of the optical film of the present invention, a resin base material provided if necessary, and the near-infrared light shielding layer will be described.

[Optical function layer]
The optical functional layer according to the present invention includes at least vanadium dioxide-containing fine particles and at least two types of binder resins having different glass transition temperatures.

[Vanadium dioxide-containing fine particles]
The crystal form of the vanadium dioxide-containing fine particles according to the present invention is not particularly limited, but from the viewpoint of efficiently expressing thermochromic properties (automatic light control), rutile vanadium dioxide-containing fine particles (VO ₂ -containing fine particles) are used. It is particularly preferable to use it.

Since the rutile VO ₂ -containing fine particles have a monoclinic structure below the transition temperature, they are also called M-type. The vanadium dioxide-containing fine particles according to the present invention may contain other crystal-type VO ₂ -containing fine particles such as A-type or B-type within a range not impairing the purpose.

  The vanadium dioxide-containing fine particles according to the present invention are preferably present in a state where the number average particle diameter of primary particles and secondary particles is less than 200 nm in the optical functional layer.

  Again, the average particle size of the vanadium dioxide-containing fine particles in the optical functional layer can be determined according to the following method.

  First, the side surface of the optical functional layer containing vanadium dioxide-containing fine particles is trimmed using a microtome or the like to expose the cross section of the optical functional layer as shown in FIG. Next, the exposed cross section is photographed at 10,000 to 100,000 times using a transmission electron microscope (TEM). The particle size of all the vanadium dioxide-containing fine particles present in a certain region of the photographed cross section is measured. At this time, the vanadium dioxide-containing fine particles to be measured are preferably in the range of 50 to 300. In the photographed vanadium dioxide-containing fine particle group, primary particles and secondary particles are mixed as shown in FIG. 1, and the particle size of the primary particles of vanadium dioxide is the diameter of each independent particle. . If it is not spherical, the projected area of the particle is converted into a circle, and its diameter is taken as the particle size. On the other hand, for the secondary particles of vanadium dioxide in which two or more particles are aggregated, after determining the projected area of the entire aggregate, the projected area is converted into a circle, and the diameter is calculated as the The aggregated secondary particles are defined as one particle. The number average diameter is obtained for each diameter of the primary particles and secondary particles obtained as described above. Since the cut-out cross-sectional portion has a variation in particle distribution, the measurement of the number-average diameter is performed for 10 cross-sectional areas of different scenes, the total number-average diameter is obtained, and the number-average particle referred to in the present invention The diameter.

  The preferred number average particle size of the primary particles and secondary particles in the vanadium dioxide-containing fine particles according to the present invention is less than 200 nm, more preferably in the range of 1 to 180 nm, and more preferably in the range of 5 to 100 nm. And most preferably in the range of 10 to 80 nm.

  The primary particle diameter of the vanadium dioxide-containing fine particles is preferably in the range of 1 to 150 nm, more preferably in the range of 5 to 100 nm, and most preferably in the range of 10 to 50 nm. .

  In the optical film of the present invention, the primary particle number ratio of the vanadium dioxide-containing fine particles in the optical functional layer, which can be determined by the above measurement method, is 30% by number or more of the total number of primary particles and secondary particles. Preferably, it is 50% by number or more, particularly preferably 70% by number or more. The ideal upper limit is 100% by number, but the current maximum value is 95% by number or less.

  In addition, the aspect ratio of the vanadium dioxide-containing fine particles is preferably in the range of 1.0 to 3.0.

  The vanadium dioxide-containing fine particles having such characteristics have a sufficiently small aspect ratio and isotropic shape, and therefore have good dispersibility when added to a solution. In addition, since the single crystal has a sufficiently small particle size, it can exhibit better thermochromic properties than conventional fine particles.

In the vanadium dioxide-containing fine particles according to the present invention, in addition to vanadium dioxide (VO ₂ ), for example, tungsten (W), molybdenum (Mo), niobium (Nb), tantalum (Ta), tin (Sn), rhenium (Re) ), Iridium (Ir), osmium (Os), ruthenium (Ru), germanium (Ge), chromium (Cr), iron (Fe), gallium (Ga), aluminum (Al), fluorine (F) and phosphorus (P It may contain at least one element selected from the group consisting of By adding such an element, it becomes possible to control the phase transition characteristics (particularly the light control temperature) of the vanadium dioxide-containing fine particles. In addition, about 0.1-5.0 atomic% is sufficient for the total amount of such an additive with respect to the vanadium dioxide containing fine particle finally obtained with respect to a vanadium (V) atom.

  Further, the concentration of the vanadium dioxide-containing fine particles in the optical functional layer according to the present invention is not particularly limited, but is generally preferably in the range of 5 to 60% by mass with respect to the total mass of the optical functional layer, more preferably. Is in the range of 5 to 40% by mass, more preferably in the range of 5 to 30% by mass.

(1: Method for producing vanadium dioxide-containing fine particles)
In general, a method for producing vanadium dioxide-containing fine particles includes a method of pulverizing a VO ₂ sintered body synthesized by a solid phase method, and a vanadium compound such as vanadium pentoxide (V ₂ O ₅ ) or ammonium vanadate as a raw material. And an aqueous synthesis method in which particles are grown while synthesizing VO ₂ in the liquid phase.

As a method for producing vanadium dioxide-containing fine particles according to the present invention, VO ₂ -containing fine particles are synthesized in a liquid phase using a vanadium compound as a raw material in that the average primary particle size is small and variation in particle size can be suppressed. However, an aqueous synthesis method in which particles are grown is preferable.

  Furthermore, examples of the aqueous synthesis method include a hydrothermal synthesis method and an aqueous synthesis method using a supercritical state. Details of the hydrothermal synthesis method will be described later. The details of the water-based synthesis method using the supercritical state (also referred to as supercritical hydrothermal synthesis method) are disclosed in, for example, paragraph numbers (0011) and (0015) to (0018) of JP-A-2010-58984. ) Can be referred to.

Among the above aqueous synthesis methods, in the present invention, the hydrothermal synthesis method is applied, and the aqueous synthesis method is used to prepare an aqueous dispersion containing vanadium dioxide-containing fine particles, and the vanadium dioxide-containing fine particles in the aqueous dispersion are dried. The number average particle diameter of the primary particles and the secondary particles can be obtained by preparing the optical functional layer forming coating solution and forming the optical functional layer using the optical functional layer forming coating solution in this state. An optical functional layer according to the present invention containing vanadium dioxide-containing fine particles having a preferred number average particle diameter of less than 200 nm can be formed. In addition, as a method for producing vanadium dioxide-containing fine particles, if necessary, fine TiO ₂ fine particles that serve as the core of particle growth are added as core particles, and the core particles are grown to produce vanadium dioxide-containing fine particles. You can also
When an aqueous binder resin is used as the binder resin, the vanadium dioxide-containing fine particles are separated without drying the vanadium dioxide-containing fine particles in the aqueous dispersion after preparing the aqueous dispersion containing the vanadium dioxide-containing fine particles. It is preferable to prepare a coating solution for forming an optical functional layer by mixing with an aqueous binder resin solution in a dispersed state.
Moreover, when using hydrophobic binder resin as binder resin, after preparing as an aqueous dispersion containing the above-mentioned vanadium dioxide-containing fine particles, solvent substitution is performed so as not to dry the vanadium dioxide-containing fine particles, and vanadium dioxide-containing It is preferable to prepare a coating solution for forming an optical functional layer by mixing with a hydrophobic binder resin solution in a dispersed state in which fine particles are separated.

  Next, the details of the method for producing vanadium dioxide-containing fine particles by a hydrothermal method suitable for the present invention will be described.

  Below, the manufacturing process of the vanadium dioxide containing fine particle by a typical hydrothermal method is shown.

(Process 1)
A substance (I) containing vanadium (V), hydrazine (N ₂ H ₄ ) or a hydrate thereof (N ₂ H ₄ .nH ₂ O), and water are mixed to prepare a solution (A). This solution may be an aqueous solution in which the substance (I) is dissolved in water, or a suspension in which the substance (I) is dispersed in water.

Examples of the substance (I) include divanadium pentoxide (V ₂ O ₅ ), ammonium vanadate (NH ₄ VO ₃ ), vanadium trichloride (VOCl ₃ ), sodium metavanadate (NaVO ₃ ), and the like. . The substance (I) is not particularly limited as long as it is a compound containing pentavalent vanadium (V). Hydrazine (N ₂ H ₄ ) and its hydrate (N ₂ H ₄ .nH ₂ O) function as a reducing agent for the substance (I) and have a property of being easily dissolved in water.

In the solution (A), an element is added to the finally obtained single crystal fine particles of vanadium dioxide (VO ₂ ). Therefore, the solution (A) may further contain a substance (II) containing the element to be added. Examples of the element to be added include tungsten (W), molybdenum (Mo), niobium (Nb), tantalum (Ta), tin (Sn), rhenium (Re), iridium (Ir), osmium (Os), ruthenium ( Ru), germanium (Ge), chromium (Cr), iron (Fe), gallium (Ga), aluminum (Al), fluorine (F), or phosphorus (P).

By adding these elements to the finally obtained vanadium dioxide (VO ₂ ) -containing single crystal fine particles, the thermochromic properties of the vanadium dioxide-containing fine particles, in particular, the transition temperature can be controlled.

Further, the solution (A) may further contain a substance (III) having oxidizing property or reducing property. Examples of the substance (III) include hydrogen peroxide (H ₂ O ₂ ). By adding the substance C having oxidizing property or reducing property, the pH of the solution can be adjusted, or the substance containing vanadium (V) as the substance (I) can be uniformly dissolved.

(Process 2)
Next, a hydrothermal reaction treatment is performed using the prepared solution (A). Here, “hydrothermal reaction” means a chemical reaction that occurs in hot water (subcritical water) whose temperature and pressure are lower than the critical point of water (374 ° C., 22 MPa). The hydrothermal reaction treatment is performed, for example, in an autoclave apparatus. Single crystal fine particles containing vanadium dioxide (VO ₂ ) are obtained by the hydrothermal reaction treatment.

  The conditions of the hydrothermal reaction treatment (for example, the amount of reactants, the treatment temperature, the treatment pressure, the treatment time, etc.) are set as appropriate, but the temperature of the hydrothermal reaction treatment is, for example, within the range of 250 to 350 ° C. Preferably, it exists in the range of 250-300 degreeC, More preferably, it exists in the range of 250-280 degreeC. By reducing the temperature, the particle diameter of the obtained single crystal fine particles can be reduced, but if the particle diameter is excessively small, the crystallinity is lowered. Moreover, it is preferable that the time of a hydrothermal reaction process exists in the range of 1 hour-5 days, for example. Increasing the time can control the particle size and the like of the obtained single crystal fine particles, but an excessively long processing time increases the energy consumption.

(Process 3)
If necessary, the surface of the obtained vanadium dioxide-containing fine particles may be subjected to a coating treatment or a surface modification treatment with a resin. Thereby, the surface of the vanadium dioxide-containing fine particles is protected, and surface-modified single crystal fine particles can be obtained. In the present invention, among these, it is a preferable aspect that the surface of the vanadium dioxide-containing fine particles is coated with the binder resin according to the present invention having a glass transition temperature of 65 ° C. or lower.
The “coating” referred to in the present invention may be a state where the entire surface of the particle is completely covered with the resin with respect to the vanadium dioxide-containing fine particles, or a part of the particle surface is covered with the resin. It may be in a state. Preferably, a state where 50% or more of the total area of the particle surface is covered is good, and a state where 80% or more is covered is more preferable.

Through the above steps 1 to 3, a dispersion liquid containing single crystal fine particles containing thermochromic vanadium dioxide (VO ₂ ) is obtained.

<Removal of impurities in vanadium dioxide-containing fine particle dispersion>
The dispersion of vanadium dioxide-containing fine particles prepared by the above aqueous synthesis method contains impurities such as residues generated in the synthesis process, and secondary aggregated particles are generated when the optical functional layer is formed. This may trigger a deterioration factor in the long-term storage of the optical functional layer, and it is preferable to remove impurities at the stage of the dispersion in advance.

  As a method for removing impurities in the vanadium dioxide-containing fine particle dispersion, conventionally known means for separating foreign substances and impurities can be applied. For example, the vanadium dioxide-containing fine particle dispersion is subjected to centrifugation, and vanadium dioxide-containing A method of precipitating fine particles, removing impurities in the supernatant, adding and dispersing the dispersion medium again, or a method of removing impurities out of the system using an exchange membrane such as an ultrafiltration membrane may be used. From the viewpoint of preventing aggregation of vanadium-containing fine particles, a method using an ultrafiltration membrane is most preferable.

  Examples of the material for the ultrafiltration membrane include cellulose, polyethersulfone, and polytetrafluoroethylene (abbreviation: PTFE). Among these, polyethersulfone and PTFE are preferably used.

(2: Preparation method of solvent dispersion containing vanadium dioxide-containing fine particles: solvent substitution treatment)
In the present invention, after preparing an aqueous dispersion containing vanadium dioxide-containing fine particles by the above-mentioned aqueous synthesis method, the vanadium dioxide-containing fine particles are obtained as a water-based dispersion by a solvent replacement step without passing through a drying process. It is preferred to prepare a solvent dispersion containing.

  The solvent replacement step is composed of a concentration step of concentrating a dispersion containing vanadium dioxide-containing fine particles and a solvent dilution step of adding a solvent to the concentrate to dilute, and includes a concentration step and a subsequent solvent dilution step. It is preferable that the treatment operation is repeated twice or more to prepare a non-aqueous solvent dispersion containing vanadium dioxide-containing fine particles.

  As a concentration means used in the step of concentrating the dispersion containing specific vanadium dioxide-containing fine particles, an ultrafiltration method is preferable.

  Hereinafter, a detailed method of the solvent replacement process will be described.

  The solvent applicable in the solvent substitution treatment according to the present invention is an organic solvent, and preferably a non-aqueous organic solvent. Finally, this is a step of preparing a solvent dispersion containing vanadium dioxide-containing fine particles by replacing water, which is a medium constituting the aqueous dispersion containing vanadium oxide-containing fine particles, with an organic solvent. By using a solvent dispersion, compatibility with the hydrophobic binder resin forming the optical functional layer is improved, and an optical functional layer with high uniformity can be formed.

  The solvent is not particularly limited and can be appropriately selected. For example, ketone solvents such as acetone, dimethyl ketone and methyl ethyl ketone, alcohol solvents such as methanol, ethanol and isopropyl alcohol, and chlorine solvents such as chloroform and methylene chloride. Solvents, aromatic solvents such as benzene and toluene, ester solvents such as methyl acetate, ethyl acetate and butyl acetate, glycol ether solvents such as ethylene glycol monomethyl ether and ethylene glycol dimethyl ether, dioxane, hexane, octane, diethyl ether, Any material that dissolves the hydrophobic binder resin to be applied at the same time, such as dimethylformamide, can be used.

  A specific solvent replacement process will be described with reference to the drawings.

  FIG. 4 is a schematic process diagram showing an example of a solvent replacement processing apparatus applicable to the present invention.

  A solvent replacement processing apparatus 10 shown in FIG. 4 includes a preparation tank 11 for storing the dispersion liquid 12 containing the vanadium dioxide-containing fine particles prepared above, a solvent stock tank 17 for storing a solvent 18 for dilution, and a solvent 18. An ultrafiltration unit 15 is disposed as a concentrating means in the solvent supply line 19 to be added to the preparation tank 11, the circulation line 13 for circulating the preparation tank 11 by the circulation pump 14, and the circulation line 13.

  Step (A) The dispersion liquid containing the vanadium dioxide-containing fine particles prepared by the above method is stored in the preparation kettle 11 as the dispersion liquid 12, and is circulated by the circulation pump 14. The water is discharged from the discharge port 16 and concentrated to a predetermined concentration. As a standard of concentration, it concentrates to 20 volume% with respect to the initial volume. It is preferable to avoid excessive concentration beyond this because particle aggregation occurs as the particle density increases. In this concentration operation, it is important not to dry the dispersion.

  Step (B) Next, 80% by mass of the solvent 18 is added from the solvent stock kettle 17 via the solvent supply line 19 to the dispersion 12 concentrated to 20% by volume, and sufficiently stirred and mixed. A primary solvent-substituted dispersion 12 is prepared.

  Step (C) Next, in the same manner as in the above step (A), the medium (water + solvent) in the dispersion is discharged 16 outside the system by the ultrafiltration unit 15 while being circulated by the circulation pump P. Concentrate again to a concentration of 20% by volume.

  Step (D) Next, in the same manner as in the above step (B), 80% by mass of the solvent 18 is added from the solvent stock kettle 17 via the solvent supply line 19 to the concentrated dispersion, and the mixture is sufficiently stirred. Mixing is performed to prepare the first solvent-dispersed dispersion liquid 12.

  Step (E) Finally, the concentration and solvent dilution operations in Step (A) and Step (B) are repeated at least twice, so that the water content is within the range of 0.1 to 5.0% by mass. A solvent dispersion containing the adjusted vanadium dioxide-containing fine particles is prepared. The water content can be determined by measuring by, for example, the Fisher method.

  That is, the solvent dispersion liquid containing vanadium dioxide-containing fine particles according to the present invention can contain water to some extent, and is 30% by mass or less, preferably 10% by mass or less, and particularly preferably 5.0% by mass. % Or less. Moreover, a minimum is 0.01 mass% or more, Preferably it is 0.05 mass% or more, Most preferably, it is 0.1 mass%. Therefore, as a moisture content, it is an especially preferable aspect that it exists in the range of 0.1-5.0 mass%. If the water content in the solvent dispersion is 30% by mass or less, the film forming property of the coexisting hydrophobic binder can be prevented at the time of forming the optical functional layer, and the haze can be reduced to 0.01% by mass. % Or more, the change width between the infrared transmittance and the infrared shielding rate at the time of temperature change can be increased to some extent. In particular, when the water content is 5.0% by mass or less, it is possible to further suppress the effect of the oxidation of the vanadium dioxide-containing fine particles and the film forming property of the coexisting hydrophobic binder, and maintain the haze at a lower level. can do. Moreover, by setting it as 0.1 mass% or more, the change width of the infrared rays transmittance | permeability at the time of a temperature change and an infrared shielding factor can further be expanded, and it is preferable conditions.

Examples of the ultrafiltration method used in the solvent replacement treatment include Research Disclosure No. 1; 10208 (1972), no. 13122 (1975) and no. 16351 (1977) and the like can be referred to. Pressure differences and flow rates that are important as operating conditions can be selected with reference to the characteristic curves described in Haruhiko Oya's “Membrane Utilization Technology Handbook”, Koshobo Publishing (1978), p275.
For ultrafiltration membranes, organic membranes, flat plate types, spiral types, cylindrical types, hollow fiber types, hollow fiber types, etc., already incorporated as modules, are available from Asahi Kasei Corporation, Daicel Chemical Co., Ltd. ( Although commercially available from Toray Industries, Inc. and Nitto Denko Corporation, etc., ceramic films such as NGK Co., Ltd. and Noritake Corporation are preferred as the solvent-resistant film.

Specifically, for example, Vivaflow 50 (effective filtration area 50 cm ² , fractional molecular weight 5000) manufactured by Sartorius steady is used as a filtration membrane, and ultrafiltration is performed at a flow rate of 300 ml / min (minutes), a hydraulic pressure of 100 kPa, and room temperature. Examples thereof include an ultrafiltration device having a filtration membrane made of polyethersulfone and a molecular weight cut off of 300,000 (Pericon 2 cassette, manufactured by Nihon Millipore Corporation).

(Binder resin)
As the binder resin contained in the optical functional layer according to the present invention, at least two types having different glass transition temperatures are used. In particular, the present invention is characterized in that at least one glass transition temperature of the binder resin is 65 ° C. or lower.

(Binder resin having a glass transition temperature of 65 ° C or lower)
The glass transition temperature is 65 ° C. or lower (hereinafter, the glass transition temperature of 65 ° C. or lower is also referred to as “low Tg”). The binder resin is not particularly limited, and is a hydrophobic binder resin described later. It may be a water-based binder resin.
In addition, the binder resin according to the present invention preferably has at least one glass transition temperature of 75 ° C. or higher from the viewpoint of effect expression. The glass transition temperature is 75 ° C. or higher (hereinafter, the glass transition temperature of 75 ° C. or higher is also referred to as “high Tg”). The binder resin is not particularly limited, and is a hydrophobic binder resin described later. It may be a water-based binder resin.

(Glass-transition temperature)
In addition, the glass transition temperature Tg here is measured at a temperature rising rate of 20 ° C./min using a commercially available differential scanning calorimeter, and is determined at an intermediate glass transition temperature (Tmg) determined according to JIS K7121 (1987). It is. As a specific method for measuring the glass transition temperature Tg of the binder resin, it is measured using a differential scanning calorimeter DSC220 manufactured by Seiko Instruments Inc. according to JIS K7121 (1987).

(Hydrophobic binder resin)
As described above, in the optical functional layer according to the present invention, a hydrophobic binder resin can be used as a low Tg and high Tg binder resin.

  The hydrophobic binder resin here means a resin having a dissolution amount of less than 1.0 g at a liquid temperature of 25 ° C. with respect to 100 g of water, more preferably a resin having a dissolution amount of less than 0.5 g. More preferably, the resin has a dissolution amount of less than 0.25 g.

  The hydrophobic binder resin applicable to the present invention is preferably a resin polymerized in a curing process using a hydrophobic resin or a monomer of a hydrophobic binder resin.

  Examples of the hydrophobic binder resin applicable to the present invention include polyethylene, polypropylene, ethylene-propylene copolymer, olefin polymer such as poly (4-methyl-1-pentene), acrylate copolymer; vinyl chloride Halogen-containing polymers such as chlorinated vinyl resins; styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyethylene terephthalate, polybutylene Polyesters such as terephthalate and polyethylene naphthalate; polyamides such as nylon 6, nylon 66, nylon 610; polyacetal; polycarbonate; polyphenylene oxide; polyphenylene sulfide; -Terketone; Polysulfone; Polyethersulfone; Polyoxybenzylene; Polyamideimide; ABS resin (acrylonitrile-butadiene-styrene resin), ASA resin (acrylonitrile-styrene-acrylate resin), cellulose blended with polybutadiene rubber and acrylic rubber Resin, butyral resin, and the like.

  In addition, as a kind of hydrophobic binder resin applicable to the present invention, a resin that uses a monomer of a hydrophobic binder resin and is polymerized in a curing treatment step can be exemplified, and its representative hydrophobic binder resin material Examples include compounds that are cured by irradiation with active energy rays, and specifically include a radical polymerizable compound that is cured by a polymerization reaction with radical active species and a cationic polymerizable compound that is cured by a cationic polymerization reaction with cationic active species. Can do.

  Examples of the radical polymerizable compound include a compound having an ethylenically unsaturated bond capable of radical polymerization. Examples of the compound having an ethylenically unsaturated bond capable of radical polymerization include acrylic acid, methacrylic acid, itaconic acid, and crotonic acid. , Unsaturated carboxylic acids such as isocrotonic acid and maleic acid and their salts, esters, urethanes, amides and anhydrides, acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, unsaturated urethanes, etc. These radically polymerizable compounds are mentioned. Specifically, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, bis (4-acryloxypolyethoxyphenyl) propane, neopentyl glycol Diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol Tetraacrylate, dipentaery Acrylic acid derivatives such as lithol tetraacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, N-methylol acrylamide, diacetone acrylamide, epoxy acrylate, methyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate , Lauryl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylol Methacryl derivatives such as tan trimethacrylate, trimethylolpropane trimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, and other derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate, triallyl trimellitate Is mentioned.

  Various known cationic polymerizable monomers can be used as the cationic polymerizable compound. For example, JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, Examples thereof include epoxy compounds, vinyl ether compounds, oxetane compounds and the like exemplified in JP-A-2001-220526.

  It is preferable to contain a photopolymerization initiator together with the above compound. As the photopolymerization initiator, any known photopolymerization initiators published in “Application and Market of UV / EB Curing Technology” (CMC Publishing Co., Ltd., edited by Yoneho Tabata / edited by Radtech Research Association) may be used. it can.

  In the present invention, after applying a coating liquid for forming an optical functional layer containing each constituent material and a solvent dispersion containing vanadium dioxide-containing fine particles, for example, on a transparent substrate, thereafter, ultraviolet rays, electron beams, etc. Irradiate active energy rays. The composition which comprises the optical function layer thin film formed by this hardens | cures rapidly.

  As the light source of the active energy ray, in the case of irradiating ultraviolet rays, for example, ultraviolet LED, ultraviolet laser, mercury arc lamp, xenon arc lamp, low pressure mercury lamp, fluorescent lamp, carbon arc lamp, tungsten-halogen copying lamp, and sunlight. Can be used. In the case of curing with an electron beam, it is usually cured with an electron beam having an energy of 300 eV or less, but it can also be cured instantaneously with an irradiation amount of 1 to 5 Mrad.

  The low Tg hydrophobic binder resin applicable to the present invention is not particularly limited. For example, any of the hydrophobic binder resins having a glass transition temperature of 65 ° C. or lower may be used. For example, the Tg is different. What is necessary is just to adjust to preferable Tg combining the monomer component of several acrylic acid ester. Also, Nippon Synthetic ester resin polyester (for example, LP050 (Tg: 10 ° C), TP290 (Tg: 10 ° C), LP035 (Tg: 20 ° C), LP033 (Tg: 15 ° C), TP217 (Tg: 40) ° C)), Toyobo's ester resin byron (for example, Byron 245 (Tg: 60 ° C), Byron GK890 (Tg: 17 ° C), Byron 103 (Tg: 47 ° C)), Sekisui Chemical Butyral resin eslek (for example, BL-10 (Tg: 59 ° C.), BL-S (Tg: 61 ° C.), BM-S (Tg: 60 ° C.), Mitsubishi Rayon acrylic resin dialnal (for example, BR-117 (Tg: 35) ° C), BR-102 (Tg: 20 ° C), BR-64 (Tg: 55 ° C)), Fujikura Kasei's acrylic resin (for example, LS701 (Tg: 10 ° C)) Which may be a commercially available product.

  Moreover, the high Tg hydrophobic binder resin that can be suitably applied to the present invention is not particularly limited. For example, any of the hydrophobic binder resins may be used as long as the glass transition temperature is 75 ° C. or higher. Similar to the low Tg binder resin, a plurality of acrylate monomer components having different Tg may be combined, or commercially available products may be used. Commercially available products include Toyobo ester-based virons (for example, UR4800 (Tg: 106 ° C.), GK880 (Tg: 84 ° C.), 885 (Tg: 79 ° C.)), Sekisui Chemical's butyral resin es-leck (for example, KS- 10 (Tg: 106 ° C.), BX-1 (Tg: 90 ° C.), Mitsubishi Rayon acrylic resin dialnal (for example, BR-80 (Tg: 105 ° C.), BR-77 (Tg: 80 ° C.)) Commercial products such as Kuraray butyral resin mobital (for example, BL16 (Tg: 84 ° C.), B60T (Tg: 72 ° C.)), Fujikura Kasei acrylic resin (for example, LH101 (Tg: 105 ° C.)) Also good.

(Water-based binder resin)
As described above, in the optical functional layer according to the present invention, an aqueous binder resin can also be used as a binder resin having a low Tg and a high Tg.

  The aqueous binder resin here is a resin that dissolves 1.0 g or more with respect to 100 g of water at 25 ° C. Moreover, after making it melt | dissolve in a hot water, the resin similarly melt | dissolved at 25 degreeC is also defined as the water-system binder resin said by this invention.

  Examples of the aqueous binder resin useful for the formation of the optical functional layer according to the present invention include gelatins, graft polymers of gelatin and other polymers, proteins such as albumin and casein, celluloses, sodium alginate, and cellulose sulfate. , Dextrin, dextran, saccharide derivatives such as dextran sulfate, natural materials such as thickening polysaccharides, polyvinyl alcohols, polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylic Acrylic resins such as nitrile copolymer, vinyl acetate-acrylic acid ester copolymer, or acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid Acid-acrylic acid esthetic Styrene acrylate resin such as copolymer, styrene-α-methylstyrene-acrylic acid copolymer, or styrene-α-methylstyrene-acrylic acid-acrylic 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 Vinyl acetate copolymers such as copolymers, vinyl naphthalene-maleic acid copolymers, vinyl acetate-maleic acid ester copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-acrylic acid copolymers, and the like Of the salt.

  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 fine 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.

  The low-Tg aqueous binder resin applicable to the present invention is not particularly limited, and for example, any resin having a glass transition temperature of 65 ° C. or lower among the above-mentioned aqueous binder resins may be used. Commercial products such as GM-14 (PVA, Nippon Gohsei, Tg: 58 ° C), Gohsenx LW-100GT (PVA, Nihon Gosei, Tg: -0.5 ° C) and poly (2-hydroxyethyl acrylate) (special Open 2011-65799, Synthesis Example 2, Tg: −15 ° C.).

  The high-Tg aqueous binder resin applicable to the present invention is not particularly limited. For example, any of the aqueous binder resins having a glass transition temperature of 75 ° C. or higher may be used. PVA R1130 (PVA, Kuraray, Tg: 80 ° C.), Kuraray PVA PVA 235 (PVA, Kuraray, Tg: 70 ° C.), Gohsenol N-300 (PVA, Nihon Gosei, Tg: 85 ° C.), Polyvinylpyrrolidone K— Commercial products such as 30 (PVP, manufactured by Nippon Shokubai, Tg: 85 ° C.), Metrose MCE-25 (methyl cellulose, manufactured by Shin-Etsu Chemical, Tg: 150 ° C.) may be used.

[Other additives for optical functional layers]
Various additives that can be applied to the optical functional layer 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, and JP-A-62-261476, JP-A-57-74192, and JP-A-57-87989. , JP-A-60-27285, JP-A-61-14659, 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, and JP-A-4-219266 Fluorescent brighteners, sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and other pH adjusters, antifoaming agents, Lubricants and other lubricants, antiseptics, antifungal agents, antistatic agents, matting agents, heat stabilizers, antioxidants, flame retardants, crystal nucleating agents, inorganic particles, organic particles, viscosity reducing agents, lubricants, infrared absorption Examples include various known additives such as agents, dyes, and pigments.

[Method for forming optical functional layer]
Although there is no restriction | limiting in particular as a formation method of the optical function layer which concerns on this invention, As a formation method of the optical function layer 3 which is a 1st embodiment, when using hydrophobic binder resin as binder resin, vanadium dioxide containing As the fine particles, vanadium dioxide-containing fine particles prepared by an aqueous synthesis method are used, and the surface of the vanadium dioxide-containing fine particles is coated with a binder resin having a glass transition temperature of 65 ° C. or less, and then the solvent replacement step without passing through a dry state. A non-aqueous optical functional layer is prepared by preparing a solvent dispersion containing vanadium dioxide-containing fine particles by mixing with a binder resin having a glass transition temperature of 75 ° C. or higher in a dispersed state where the vanadium dioxide-containing fine particles are separated from each other. Prepare a coating solution for forming, and apply the coating solution for forming the optical functional layer on a transparent substrate by a wet coating method. Coating, a method of forming an optical functional layer 3 is dried to a first embodiment is one of the preferred forming methods.

  As another example of the method of forming the optical functional layer 3 according to the first embodiment, when an aqueous binder resin is used as the binder resin, vanadium dioxide-containing fine particles prepared by an aqueous synthesis method are used as vanadium dioxide-containing fine particles. A dispersion in which the vanadium dioxide-containing fine particles exist without being associated with each other without being subjected to a drying step after the surface of the vanadium dioxide-containing fine particles is coated with an aqueous binder resin having a glass transition temperature of 65 ° C. or lower. In the liquid state, after preparing an aqueous binder resin solution in which at least the aqueous binder resin is dissolved in an aqueous solvent, it is mixed and dissolved with an aqueous binder resin having a glass transition temperature of 75 ° C. or higher to form an aqueous optical functional layer. A coating solution for forming an aqueous optical functional layer is prepared by a wet coating method. Coated on a wood, a method of forming an optical functional layer 3 as the first embodiment and dried is one of the preferred forming methods.

  The “aqueous solvent” refers to a solvent in which 50% by mass or more is water. Of course, 100% by mass containing no other solvent may be pure water, and considering the dispersion stability of the vanadium dioxide-containing fine particles, it is preferable that the content of the other organic solvent is small. The solvent constituting the aqueous solvent is not particularly limited as long as it is a solvent compatible with water, but an alcohol-based solvent can be preferably used. Among them, the boiling point is relatively close to that of water. Isopropyl alcohol is preferred.

  The wet coating method used for forming the optical functional layer is not particularly limited. For example, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a slide curtain coating method, or US Pat. No. 2,761,419 And a slide hopper coating method and an extrusion coating method described in US Pat. No. 2,761791.

  In addition, as a method for forming the hybrid optical functional layer that also serves as the resin substrate according to the second embodiment, a solution casting method can be applied. No. 2013-067074, JP 2013-123868, JP 2013-202979, JP 2014-066958, JP 2014-095729, JP 2014-159082, and the like. It can be formed according to the solution casting film forming method.

  As another method for forming the optical functional layer according to the present invention when a hydrophobic binder resin is used, as illustrated in FIGS. 2 and 4, the hydrophobic resin that is a constituent material of the transparent substrate is used. Then, a solvent dispersion containing vanadium dioxide-containing fine particles and a solvent are added and dissolved to prepare a dope for film formation, and then the solution casting method used in the conventional film formation using the dope, A method of forming a hybrid optical functional layer, which is the second embodiment also serving as a resin substrate, can be suitably used.

  Examples of the hydrophobic binder resin that can be applied by the above method include resin materials that are conventionally used in the formation of optical films, such as polyethylene terephthalate (abbreviation: PET), polyethylene naphthalate (abbreviation: PEN). Such as polyester, polyethylene, polypropylene, cellulose diacetate, cellulose triacetate (abbreviation: TAC), cellulose acetate butyrate, cellulose acetate propionate (abbreviation: CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate, and the like Derivatives of polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate (abbreviation: PC), norbornene resin, polymer Rupentene, polyetherketone, polyimide, polyethersulfone (abbreviation: PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic and polyarylates, arton Examples thereof include cycloolefin resins such as (trade name, manufactured by JSR) and Apel (trade name, manufactured by Mitsui Chemicals).

  Further, the solvent is not particularly limited. For example, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2- Trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2- Examples include propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, and the like.

  Using the dope prepared by mixing and preparing the above constituent materials, a hybrid optical functional layer that also serves as a transparent substrate is formed by a solution casting method.

<Transparent substrate>
The transparent substrate 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. However, it is possible to impart flexibility and suitability for production (manufacturing process suitability). From the viewpoint, a transparent resin film is preferable. “Transparent” in the present invention means that the average light transmittance in the visible light region is 50% or more, preferably 60% or more, more preferably 70% or more, and particularly preferably 80% or more.

  The thickness of the transparent substrate according to the present invention is preferably in the range of 30 to 200 μm, more preferably in the range of 30 to 100 μm, and still more preferably in the range of 35 to 70 μm. If the thickness of the transparent substrate is 30 μm or more, wrinkles and the like are less likely to occur during handling, and if the thickness is 200 μm or less, the followability to the curved glass surface when bonded to the glass substrate is improved. .

  The transparent substrate according to the present invention 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 optical film of the present invention is used as an automobile glass, a stretched film is more preferable.

  The transparent substrate according to the present invention has a thermal shrinkage within a range of 0.1 to 3.0% at a temperature of 150 ° C. from the viewpoint of preventing generation of wrinkles of the optical film and cracking of the optical functional layer. Is preferable, it is more preferable that it is in the range of 1.5 to 3.0%, and it is still more preferable that it is 1.9 to 2.7%.

  The transparent substrate applicable to the optical 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, cycloolefin, polyethylene, polypropylene) Etc.), polyester films (for example, polyethylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride, triacetyl cellulose film, etc. can be used, and cycloolefin films, polyester films, and triacetyl cellulose films are preferred.

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

<< Near-infrared shielding layer >>
In the optical film of the present invention, in addition to the optical functional layer, a near-infrared light shielding layer having a function of shielding at least part of the light wavelength range of 700 to 1000 nm may be provided.

  For details of the near infrared light shielding layer applicable to the present invention, for example, JP 2012-131130 A, JP 2012-139948 A, JP 2012-185342 A, JP 2013-080178 A. The constituent elements and forming methods described in JP-A-2014-089347 and the like can be referred to.

<< Use of optical film >>
As an application of the optical film of the present invention, it can be sandwiched between a pair of glass constituent members to constitute laminated glass or to be pasted on glass. This glass is used for automobiles, railway vehicles, aircrafts. Can be used for ships and buildings. It can also be used for other purposes. The glass is preferably used for construction or for vehicles. The said glass can be used for the windshield, side glass, rear glass, roof glass, etc. of a motor vehicle.

  Examples of the glass member include inorganic glass and organic glass (resin glazing). Examples of the inorganic glass include colored glass such as float plate glass, heat ray absorbing plate glass, polished plate glass, mold plate glass, netted plate glass, lined plate glass, and 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.

  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 "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

In addition, the resin described in the list of Resin 1 and Resin 2 in Table 1 is as follows.
1: Byron 200 (ester resin, manufactured by Toyobo) Tg: 67 ° C
2: EASTER6763 (ester resin, manufactured by Eastman Chemical) Tg: 80 ° C.
3: Esper 9940B (ester resin, manufactured by Hitachi Chemical) Tg: 25 ° C
4: Gohsenol GM-14 (PVA, manufactured by Nihon Gosei) Tg: 58 ° C
5: Kuraray Poval R1130 (PVA, manufactured by Kuraray) Tg: 80 ° C
6: Polyester LP050 (ester resin, manufactured by Nihon Gosei) Tg: 10 ° C
7: Byron UR4800 (ester urethane resin, manufactured by Toyobo) Tg: 106 ° C
8: Polyester TP220 (ester type, manufactured by Nihon Gosei) Tg: 70 ° C
9: Byron GK880 (ester, manufactured by Toyobo) Tg: 84 ° C
10: Byron 245 (ester resin, manufactured by Toyobo) Tg: 60 ° C
11: ESREC BL-10 (Butyral resin, manufactured by Sekisui Chemical) Tg: 59 ° C
12: ESREC KS-10 (butyral resin, manufactured by Sekisui Chemical) Tg: 106 ° C
13: Dianal BR-117 (acrylic resin, manufactured by Mitsubishi Rayon) Tg: 35 ° C.
14: Dianal BR-80 (acrylic resin, manufactured by Mitsubishi Rayon) Tg: 95 ° C
15: Arton dope (described in preparation of optical film 17 described later) Tg: 145 ° C.

<< Production of optical film >>
[Preparation of optical film 1]
(Preparation of vanadium dioxide-containing fine particle dispersion 1: no particle drying step)
0.433 g of ammonium vanadate (NH ₄ VO ₃ , manufactured by Wako Pure Chemical Industries, special grade) is mixed with 10 ml of pure water, and further hydrazine hydrate (N ₂ H ₄ · H ₂ O, manufactured by Wako Pure Chemical Industries, Ltd.). A 5% by weight aqueous solution of (special grade) was slowly added dropwise to prepare a solution having a pH value (liquid temperature of 23 ° C.) of 9.2. The prepared solution is put into a commercially available autoclave for hydrothermal reaction treatment (HU-25 type, manufactured by Sanai Kagaku Co., which has a 25 ml volume Teflon (registered trademark) inner cylinder in a SUS body) at 100 ° C. A hydrothermal reaction treatment was performed for 8 hours and subsequently at 270 ° C. for 24 hours to prepare an aqueous vanadium dioxide-containing fine particle dispersion 1 in which vanadium dioxide-containing fine particles were dispersed at a concentration of 3.0% by mass.

(Preparation of vanadium dioxide-containing fine particle dispersion 2: ultrafiltration treatment)
An ultrafiltration apparatus having a filtration membrane made of polyethersulfone and having a molecular weight cut off of 300,000 (Nippon Millipore). The vanadium dioxide-containing fine particle dispersion 1 prepared above is kept at 20 ° C. and is circulated in the system. Concentration operation was performed using the solvent displacement treatment apparatus shown in FIG. 4 equipped with Pelicon 2 cassette (manufactured by Co., Ltd.). When the initial volume of the vanadium dioxide-containing fine particle dispersion 1 was 100%, the concentration was reduced to 20% by volume. Then, ethyl alcohol was added to make 100% by volume. Next, this dispersion was concentrated again to 20% by volume, then methyl ethyl ketone was added as a solvent to make 100% by volume, and the solvent was subjected to two solvent substitution treatments. The solvent concentration of the vanadium dioxide-containing fine particles was 3% by mass. Dispersion 2 was prepared.

  The water content in the prepared vanadium dioxide-containing fine particle dispersion 2 was measured by the Karl Fischer method and found to be 4.05% by mass.

(Preparation of coating solution 1 for forming an optical functional layer)
The following constituent materials were sequentially added, mixed and dissolved to prepare a solvent-based coating solution 1 for forming an optical functional layer.

3% by weight vanadium dioxide-containing fine particle dispersion 2 (solvent: methyl ethyl ketone)
28 parts by mass of 5% by mass of hydrophobic binder resin solution (solvent: methylethylkenton, solute (hydrophobic binder resin): Byron 200 (amorphous polyester resin, manufactured by Toyobo Co., Ltd., Tg: 67 ° C.))
60 parts by mass

(Formation of optical functional layer)
On the transparent base material of a polyethylene terephthalate film (Toyobo A4300, double-sided easy-adhesion layer) having a thickness of 50 μm, using an extrusion coater, the above-prepared coating solution 1 for forming an optical functional layer has a layer thickness after drying. Wet application was performed under the condition of 1.5 μm, and then hot air of 110 ° C. was blown for 2 minutes to dry to form an optical functional layer, thereby producing an optical film 1 having the configuration shown in FIG.

[Preparation of optical film 2]
13.7 g of vanadyl triisopropoxide and 0.73 g of molybdenum pentaethoxide were dissolved in 500 ml of isopropanol. 15 ml of ion-exchanged water was added to this solution and stirred at room temperature for 72 hours, and then the solvent was removed. After crushing the residue, it was calcined at 400 ° C. for 2 hours, and then calcined in a hydrogen stream at 450 ° C. for 2 hours to obtain molybdenum-doped vanadium dioxide fine particles.

(Film formation)
The molybdenum-doped vanadium dioxide fine particles were mixed with the following composition, and an optical film 2 having a thickness of 50 μm was produced by a T-die method.
Molybdenum-doped vanadium dioxide 3 parts by mass EASTER6763 (ester resin, Eastman Chemical, Tg: 80 ° C.)
97 parts by mass

[Preparation of optical film 3]
(Preparation of vanadium dioxide-containing fine particle dispersion 3)
In the preparation of the vanadium dioxide-containing fine particle dispersion 2, the dispersion 2 was further concentrated to 20% by volume using the same solvent substitution apparatus, and then methyl ethyl ketone was added to make 100% by volume. Was performed three times to prepare a solvent-based vanadium dioxide-containing fine particle dispersion 3 having a particle concentration of 3% by mass.

  The water content in the prepared vanadium dioxide-containing fine particle dispersion 3 was measured by the Karl Fischer method and found to be 0.84% by mass.

(Preparation of coating solution for forming optical functional layer and formation of optical functional layer)
In the production of the optical film 1, Esper 9940B (ester resin, manufactured by Hitachi Chemical Co., Ltd., Tg: 25 ° C.) is used instead of Byron 200 as a hydrophobic binder resin in the preparation of the coating liquid 1 for forming the optical functional layer. Further, in place of the vanadium dioxide-containing fine particle dispersion 2, the above-prepared vanadium dioxide-containing fine particle dispersion 3 was used in the same manner except that the optical functional layer-forming coating liquid was prepared and the optical functional layer was formed. An optical film 3 was produced.

[Preparation of optical film 4]
(Preparation of vanadium dioxide-containing fine particle dispersion 4: no particle drying step)
0.433 g of ammonium vanadate (NH ₄ VO ₃ , manufactured by Wako Pure Chemical Industries, special grade) is mixed with 10 ml of pure water, and further hydrazine hydrate (N ₂ H ₄ · H ₂ O, manufactured by Wako Pure Chemical Industries, Ltd.). A 5% by weight aqueous solution of (special grade) was slowly added dropwise to prepare a solution having a pH value (liquid temperature of 23 ° C.) of 9.2. The prepared solution is put into a commercially available autoclave for hydrothermal reaction treatment (HU-25 type, manufactured by Sanai Kagaku Co., which has a 25 ml volume Teflon (registered trademark) inner cylinder in a SUS body) at 100 ° C. A hydrothermal reaction treatment was performed for 8 hours and subsequently at 270 ° C. for 24 hours to prepare vanadium dioxide-containing fine particle dispersion 4 in which vanadium dioxide-containing fine particles were dispersed at a concentration of 3.0% by mass.

(Preparation of coating solution 2 for forming an optical functional layer)
The following constituent materials were sequentially added, mixed and dissolved to prepare an aqueous optical functional layer forming coating solution 2.

3% by weight vanadium dioxide-containing fine particle dispersion 4 28 parts by weight 3% by weight boric acid aqueous solution 10 parts by weight 5% by weight binder resin solution (5% by weight aqueous solution, solute: Gohsenol GM-14 (PVA, manufactured by Nihon Gosei, Tg: 58 ° C.), Kuraray Poval R1130 (PVA, manufactured by Kuraray, Tg: 80 ° C.), mixing ratio (mass ratio) Gohsenol GM-14: Kuraray Poval R1130 = 2.5: 97.5)
60 mass parts 5 mass% surfactant aqueous solution (Softazoline LSB-R, manufactured by Kawaken Fine Chemical Co., Ltd.) 2 mass parts

(Formation of optical functional layer)
On the polyethylene terephthalate film (Toyobo A4300, double-sided easy-adhesion layer) having a thickness of 50 μm, the coating liquid 2 for forming an optical functional layer prepared above was used with an extrusion coater, and the layer thickness after drying was 1.5 μm. Wet coating was performed under the following conditions, followed by drying by blowing hot air at 110 ° C. for 2 minutes to form an optical functional layer, thereby producing an optical film 4.

[Preparation of optical film 5]
In the production of the optical film 3, in the preparation of the coating solution 1 for forming the optical functional layer, instead of Esper 9940B (ester resin, manufactured by Hitachi Chemical, Tg: 25 ° C.) as a hydrophobic binder resin, Polyester LP050 (ester system) Resin, manufactured by Nippon Gosei Co., Ltd., Tg: 10 ° C.) and Byron UR4800 (ester urethane resin, manufactured by Toyobo, Tg: 106 ° C.) (mixing ratio) (mass ratio) Esper 9940B: Polyester LP050 = 2.5: 97.5 The optical film 5 was produced in the same manner as described above.

[Preparation of optical films 6-8]
Each of the optical films 6 to 8 was prepared by preparing the optical functional layer-forming coating liquid 1 in the production of the optical film 5, as Esper 9940B (resin 1 shown in Table 1) and Polyester LP050 (table 1) as a hydrophobic binder resin. Optical films 6 to 8 were prepared in the same manner except that the resin 1 and the resin 2 described in Table 1 were used instead of the resin 2) described in 1.

[Preparation of optical film 9]
(Preparation of vanadium dioxide-containing fine particle dispersion 5: covered with a low Tg binder resin)
0.433 g of ammonium vanadate (NH ₄ VO ₃ , manufactured by Wako Pure Chemical Industries, special grade) is mixed with 10 ml of pure water, and further hydrazine hydrate (N ₂ H ₄ · H ₂ O, manufactured by Wako Pure Chemical Industries, Ltd.). A 5% by weight aqueous solution of (special grade) was slowly added dropwise to prepare a solution having a pH value (liquid temperature of 23 ° C.) of 9.2. 0.54 g of a 5 mass% solution (solvent: methyl ethyl kenton) of Polyester LP050 (ester resin, manufactured by Nippon Gosei Co., Ltd., Tg: 10 ° C., resin 1 in Table 1) was added to the prepared solution. It is put in a commercially available autoclave for hydrothermal reaction treatment (HU-25 type, manufactured by Sanai Kagaku Co., which has a 25 ml capacity Teflon (registered trademark) inner cylinder in a SUS main body), and then at 270 ° C. for 8 hours, and subsequently 270 A vanadium dioxide-containing fine particle dispersion 5 in which the vanadium dioxide-containing fine particles whose surface was coated with the polyester LP050 was dispersed at a concentration of 3.0% by mass was subjected to a hydrothermal reaction treatment at 24 ° C. for 24 hours. .

(Preparation of coating solution for forming optical functional layer and formation of optical functional layer)
In the production of the optical film 3, Byron UR4800 (ester urethane resin, manufactured by Toyobo, Tg: 106 ° C., described in Table 1) instead of Esper 9940B as a hydrophobic binder resin in the preparation of the coating solution 1 for forming the optical functional layer. In addition, using the prepared vanadium dioxide-containing fine particle dispersion 5 instead of the vanadium dioxide-containing fine particle dispersion 2, the preparation of the optical functional layer-forming coating liquid and the formation of the optical functional layer are performed. An optical film 9 was produced in the same manner as described above.

[Production of optical films 10 to 12]
In the production of the optical film 9, optical films 10 to 12 were produced in the same manner except that the resins 1 and 2 were changed to those shown in Table 1.

[Preparation of optical film 13]
(Preparation of vanadium dioxide-containing fine particle dispersion 6)
0.433 g of ammonium vanadate (NH ₄ VO ₃ , manufactured by Wako Pure Chemical Industries, special grade) is mixed with 10 ml of pure water, and further hydrazine hydrate (N ₂ H ₄ · H ₂ O, manufactured by Wako Pure Chemical Industries, Ltd.). A 5% by weight aqueous solution of (special grade) was slowly added dropwise to prepare a solution having a pH value (liquid temperature of 23 ° C.) of 9.2. 0.54 g of a 5% by mass aqueous solution of Gohsenol GM-14 (PVA, manufactured by Nippon Gosei Co., Ltd., Tg: 58 ° C.) was added to the prepared solution, and this solution was added to a commercially available autoclave for hydrothermal reaction treatment (HU manufactured by Sanai Kagakusha). -25 type, SUS main body with a 25 ml Teflon (registered trademark) inner cylinder.) And subjected to hydrothermal reaction treatment at 100 ° C. for 8 hours and then at 270 ° C. for 24 hours, Vanadium dioxide-containing fine particle dispersion 6 in which vanadium dioxide-containing fine particles coated with Gohsenol GM-14 were dispersed at a concentration of 3.0% by mass was prepared.

(Ultrafiltration treatment of vanadium dioxide-containing fine particle dispersion 6)
An ultrafiltration device (manufactured by Nippon Millipore Corporation) having a filtration membrane made of polyethersulfone and having a molecular weight cut off of 300,000 in a state where the vanadium dioxide-containing fine particle dispersion 6 is kept at 20 ° C. Concentration operation was performed using Pelicon 2 cassette), and after concentrating to 10% of the initial volume of vanadium dioxide-containing fine particle dispersion 6, water was added to make 100%, and this concentration and dilution operation was repeated three times. Then, an ultrafiltration-treated vanadium dioxide-containing fine particle dispersion 7 having a particle concentration of 3% by mass was prepared.

(Preparation of coating solution 3 for forming an optical functional layer)
The following constituent materials were sequentially added, mixed and dissolved to prepare an aqueous optical functional layer forming coating solution 3.

3 mass% vanadium dioxide-containing fine particle dispersion 7 28 mass parts 3 mass% boric acid aqueous solution 10 mass parts 5 mass% binder resin solution (5 mass% aqueous solution, solute: Kuraray Poval R1130 (PVA, manufactured by Kuraray, Tg: 80 ° C))
60 mass parts 5 mass% surfactant aqueous solution (Softazolin LSB-R, manufactured by Kawaken Fine Chemical Co., Ltd.) 2 mass parts (formation of optical functional layer)
On the polyethylene terephthalate film (Toyobo A4300, double-sided easy-adhesion layer) having a thickness of 50 μm, the coating liquid 3 for forming an optical functional layer prepared as described above was used with an extrusion coater, and the layer thickness after drying was 1.5 μm. Wet application was performed under the conditions as described above, followed by drying by blowing warm air at 110 ° C. for 2 minutes to form an optical functional layer, thereby producing an optical film 13.

[Production of Optical Film 14]
In the preparation of the vanadium dioxide-containing fine particle dispersion 5 used for the production of the optical film 9, the solvent replacement treatment was performed by a vacuum distillation method using an evaporator instead of the method using the ultrafiltration device described in FIG. Except for the above, an optical film 14 was produced in the same manner as in the production of the optical film 9 described above.

[Production of optical films 15 and 16]
Optical films 15 and 16 were produced in the same manner as in the production of the optical film 9 except that the number average particle diameter and the primary particle number ratio were changed to those shown in Table 1.

[Preparation of optical film 17]
(Preparation of dope)
First, the following methylene chloride was added to the pressure dissolution tank. The cycloolefin polymer (abbreviation: COP) and the above prepared vanadium dioxide-containing fine particle dispersion 5 were charged into a pressure dissolution tank containing an organic solvent while stirring. While this was heated and stirred, the cycloolefin polymer was dissolved, and this was added to Azumi Filter Paper No. The dope was prepared by filtration using 244.

<Dope composition>
192 parts by mass of methylene chloride Hydrophobic polymer resin: cycloolefin polymer (trade name: Arton, manufactured by JSR Corporation, Tg = 145 ° C.)
76.9 parts by mass 3% by mass of vanadium dioxide-containing fine particle dispersion 5 12.0 parts by mass

(Film formation)
Using the prepared dope, an optical film 17 which is a hybrid optical functional layer was produced according to the solution casting film forming method described in JP2014-095729A and JP2014-159082.

  Table 1 shows the configurations of the optical films 1 to 17 produced as described above.

<< Measurement of optical film characteristic values >>
About each produced said optical film, according to the following method, the number average particle diameter of the vanadium dioxide containing microparticles | fine-particles in an optical functional layer and the particle number ratio of a primary particle were measured.

  The side surface of the optical functional layer constituting each optical film was trimmed with a microtome to expose a cross section as shown in FIG. 1 or FIG. Next, the exposed cross section was photographed at a magnification of 10,000 using a transmission electron microscope (TEM). The particle size of all the vanadium dioxide-containing fine particles present in a certain region of the photographed cross section was measured.

At this time, 300 vanadium dioxide-containing fine particles were measured. The shot particles, the primary particles are single particles, as shown in FIG. 1 or FIG. 2, 2 are included and particles or the secondary particles are aggregates of vanadium dioxide primary particles VO _S The particle size measures the diameter of each independent particle. In addition, for vanadium dioxide in which two or more particles are aggregated, the projected area of the entire aggregate was obtained, and then the projected area was converted into a circle, and the diameter was taken as the particle size.

  For each diameter of the primary particles and secondary particles determined as described above, the number average diameter (nm) was determined and used as the number average particle size. Next, for each particle measured above, the ratio of primary particles to the total number of particles (particle number%) was determined.

<< Evaluation of optical film and optical film laminated glass >>
Each of the obtained optical films was cut into 5 pieces each having a size of 10 cm square, and the following operation was performed.

  Three acceleration test machines are prepared, and each is adjusted to 85 ° C. (no humidification), −20 ° C., 60 ° C.-80% RH, and each optical film is (85 ° C .: 1 hour) → (−20 ° C .: 1 hour) → (60 ° C.-80% RH: 1 hour), this was repeated 25 times and 50 times. In this way, two types of samples for evaluation (each with 25 repetitions and 50 repetitions) were prepared for each of the optical films thus prepared. Next, the following evaluations were performed.

(Evaluation of haze)
About each sample of each produced said optical film, haze (%) was measured using the haze meter (Nippon Denshoku Industries Co., Ltd. make, NDH2000) at room temperature, and the haze was evaluated according to the following reference | standard. The smaller the haze (%), the better.

A: Haze is less than 2.0% B: Haze is 2.0% or more and less than 3.0% B: Haze is 3.0% or more and less than 5.0% B : 5.0% or more and less than 8.0% ×: 8.0% or more

(Storability)
About each sample of each produced said optical film, the surface (film surface) was observed and evaluated as follows. In addition, preservability shall be so good that neither a crack nor film | membrane peeling will be seen.

○: Neither cracking nor film peeling of 0.5 mm or more was observed in any of the 5 optical films. ○ △: Cracking or film peeling of 5 optical films with a size of 0.5 mm or more and less than 3 mm. The total number of occurrences of is 1 or more and 2 or less. Δ: In 5 optical films, the total number of occurrences of cracks or film peeling of 0.5 mm or more and less than 3 mm is 3 or more and 5 or less. Δ ×: In 5 optical films, the total number of cracks and film peelings of 0.5 mm or more and less than 3 mm is 6 or more and 10 or less. ×: In 5 optical films, The total number of occurrences of cracks and film peeling with a size of 0.5 mm or more and less than 3 mm is 11 or more, or the total number of cracks or film peeling with a size of 3 mm or more is 1 or more.

[Evaluation of thermochromic properties]
The glass (optical film bonding glass) which bonded each produced said optical film as follows was produced. About each produced optical film bonding glass, the heat insulation of summer assumption and the heat insulation of winter assumption were evaluated, and the thermochromic property of each produced said optical film was determined.

<< Production of optical film laminated glass >>
Each of the optical films prepared above is made of a transparent adhesive sheet (manufactured by Nitto Denko Corporation, LUCIACS CS9621T) in a size of 15 cm × 20 cm of a glass plate having a thickness of 1.3 mm (manufactured by Matsunami Glass Kogyo Co., Ltd., “Slide Glass White Edge Polish”). The optical film laminated glass was prepared for each of the optical films prepared as described above.

(Evaluation of heat insulation in summer)
<Measurement environment>
Measurement environment: An environmental room was used on the wall surface of an environmental test room having a room temperature of 28 ° C. so that the optical film-laminated glass was placed so that the inner side was an optical film, and a Japanese Cool Biz room was assumed.

  -A 150 W halogen lamp was lit from a position 50 cm away from the outside of the environmental test room where the optical film-laminated glass was placed, assuming the summer sun.

  -Furthermore, assuming that the optical film laminated glass is heated by the accumulation of sunlight irradiation, the laminated glass was heated to 70 ° C. with a thermocouple.

  A thermometer was installed at a position 1 m away from the optical film-laminated glass in the environmental test chamber, the temperature after 1 hour was measured under the above conditions, and the heat shielding property was evaluated according to the following criteria.

◎: Temperature after 1 hour is less than 29 ℃, almost no temperature increase due to external light ○: Temperature after 29 hours is 29 ℃ or more and 32 ℃ or less ○ △: After 1 hour The temperature is 32 ° C. or more and 34 ° C. or less. Δ: The temperature after one hour has passed is 34 ° C. or more and 36 ° C. or less. ×: The temperature after one hour has passed is 36 ° C. or more, which is a harsh environment.

(Evaluation of heat insulation in winter)
<Measurement environment>
Measurement environment: An optical film-laminated glass was placed on the wall surface of an environmental test room having a room temperature of 20 ° C. so that the inner side was an optical film, and an environmental room assuming a Japanese Warm Biz room was used.

  A 100 W halogen lamp was lit from a position 50 cm away from the outside where the optical film-laminated glass in the environmental test room was placed, assuming the sun in winter.

  A thermometer was installed at a position 1 m away from the optical film-laminated glass in the environmental test chamber, the temperature after 1 hour was measured under the above conditions, and the heat shielding property was evaluated according to the following criteria.

◎: Temperature after 1 hour is 26 ° C or higher, and heat energy from external light has entered moderately. ○: Temperature after 24 hours is more than 24 ° C and less than 26 ° C. Later temperature is 22 ° C. or more and 24 ° C. or less. Δ: Temperature after 21 hours is 21 ° C. or more and 22 ° C. or less. X: Many near infrared light is unconditionally shielded and after 1 hour. The temperature is less than 21 ° C

(Scratch resistance evaluation)
As an evaluation of scratch resistance, each optical film was rubbed using a load variation type frictional wear test system HHS2000 manufactured by Haydon, 10 reciprocations at a load of 50 g, a speed of 500 mm / ms, and a distance of 50 mm, using steel wool # 0000. . Haze values before and after rubbing were measured at room temperature using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH2000), and the difference was evaluated. In the scratch resistance evaluation, the smaller the difference in haze value, the better.

◎: Haze value difference is 1.0% or less ○: Haze value difference is 2.0% or less ○ △: Haze value difference is 3.0% or less △: Haze value Is less than 5.0%. X: Difference in haze value is greater than 5.0%

DESCRIPTION OF SYMBOLS 1 Optical film 2 Transparent base material 3 Optical functional layer 2 + 3 Hybrid optical functional layer 4 Near-infrared light shielding layer 10 Solvent substitution processing apparatus 11 Preparation kettle 12 Dispersion liquid containing vanadium dioxide containing fine particles 13 Circulation line 14 Circulation pump 15 Ultrafiltration Part 16 Discharge port 17 Solvent stock kettle 18 Solvent 19 Solvent supply line B1, B2 Binder resin VO _S Primary particle of vanadium dioxide-containing fine particles VO _M Secondary particle of vanadium dioxide-containing fine particles

Claims (4)

An optical film having an optical functional layer containing at least vanadium dioxide-containing fine particles and a binder resin,
The optical functional layer contains at least two binder resins having different glass transition temperatures;
An optical film having at least one glass transition temperature of the binder resin of 65 ° C. or lower.   The optical film according to claim 1, wherein at least one glass transition temperature of the binder resin is 75 ° C. or higher.   The optical film according to claim 1 or 2, wherein the surface of the vanadium dioxide-containing fine particles is coated with the binder resin having a glass transition temperature of 65 ° C or lower. A method of producing an optical film comprising a step of forming an optical functional layer containing at least vanadium dioxide-containing fine particles and a binder resin
In the step,
As the vanadium dioxide-containing fine particles, using vanadium dioxide-containing fine particles prepared by an aqueous synthesis method,
After coating the surface of the vanadium dioxide-containing fine particles with a binder resin having a glass transition temperature of 65 ° C. or less, without passing through a dry state,
An optical functional layer-forming coating solution is prepared by mixing with a binder resin having a glass transition temperature of 75 ° C. or higher, and the optical functional layer-forming coating solution is applied on a transparent substrate and dried to obtain an optical functional layer. Forming an optical film.

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