JP6978227B2 - Dimming film - Google Patents

Description

The present invention relates to a photochromic film.

Conventionally, a dimming film utilizing the light scattering effect in a composite of a polymer and a liquid crystal material has been developed. In such a light control film, since the liquid crystal material has a structure in which the liquid crystal material is phase-separated or dispersed in the polymer matrix, the refractive index of the polymer and the liquid crystal material is matched, and a voltage is applied to the composite. By changing the orientation of the liquid crystal material, it is possible to control the transmission mode in which light is transmitted and the scattering mode in which light is scattered. In order to realize such driving, the dimming film is usually configured by holding a dimming layer containing the composite with a transparent conductive film.

On the other hand, as a transparent conductive film, a film including a conductive layer containing metal nanowires is being studied. If such a transparent conductive film is used for the dimming film, the flexibility can be improved.

However, when the light control film is put into practical use, it is necessary to form an electrode on the conductive layer, and at this time, the work of wiping off the light control layer component adhering to the transparent conductive film (the surface on which the electrode is formed) is performed. This is done and causes the problem of scratching the conductive layer. The conductive layer containing the metal nanowires tends to cause the problem remarkably, and the disconnection impairs the function of the light control film. In order to improve scratch resistance and protect the conductive layer, it is conceivable to form a protective layer on the conductive layer, but if the protective layer is made thicker, it becomes difficult to secure conduction from the conductive layer, and scratch resistance and continuity. It is difficult to realize a transparent conductive film that is compatible with both.

That is, in a light control film utilizing the light scattering effect of a composite of a polymer and a liquid crystal material, there is a problem that it is difficult to apply a conductive layer containing metal nanowires from the viewpoint of scratch resistance of the conductive layer.

Japanese Unexamined Patent Publication No. 2013-148678

The present invention has been made to solve the above problems, and an object thereof is to provide a transparent conductive film having excellent scratch resistance and conductivity, and the transparent conductive film can be wiped off or the like. It is an object of the present invention to provide a dimming film whose dimming function is not impaired even when subjected to work involving friction.

The light control film of the present invention includes a first transparent conductive film, a light control layer, and a second transparent conductive film in this order, and the first transparent conductive film includes a transparent base material and a transparent base material. A transparent conductive layer arranged on both sides or one side of the transparent substrate is included, and the transparent conductive layer contains a binder resin, metal nanowires, and conductive particles.
In one embodiment, the dimming layer comprises a liquid crystal compound.
In one embodiment, the average particle size X of the conductive particles and the thickness Y of the region composed of the binder resin satisfy the relationship of Y ≦ X ≦ 20Y.
In one embodiment, the average primary particle size of the conductive particles is 5 nm to 100 μm.
In one embodiment, the content ratio of the conductive particles is 0.1 part by weight to 20 parts by weight with respect to 100 parts by weight of the binder resin.
In one embodiment, the conductive particles are silver particles.
In one embodiment, the transparent conductive layer further comprises a surface conditioner.

According to the present invention, a transparent conductive film having excellent scratch resistance and conductivity is provided, and even if the transparent conductive film is subjected to work involving friction such as wiping, the dimming function is not impaired. An optical film can be provided.

It is the schematic sectional drawing of the light control film by one Embodiment of this invention. It is the schematic sectional drawing of the 1st transparent conductive film by one Embodiment of this invention.

A. Overall Configuration of the Photochromic Film FIG. 1 is a schematic cross-sectional view of the light control film according to one embodiment of the present invention. The light control film 100 includes a first transparent conductive film 110, a light control layer 120, and a second transparent conductive film 130 in this order. The first transparent conductive film 110 and the second transparent conductive film 130 may have the same configuration or different configurations.

B. First Transparent Conductive Film FIG. 2 is a schematic cross-sectional view of the first transparent conductive film according to one embodiment of the present invention. The first transparent conductive film 110 includes a transparent base material 10 and a transparent conductive layer 20 arranged on both sides or one side (one side in the illustrated example) of the transparent base material 10. The transparent conductive layer 20 includes a binder resin 21, metal nanowires 22, and conductive particles 23. In one embodiment, the first transparent conductive film 110 is arranged with the transparent conductive layer 20 on the dimming layer 120 side. In one embodiment, the light control film 100 is configured such that the light control layer 120 and the transparent conductive layer 20 are in contact with each other.

In the present invention, by including the conductive particles, good conduction can be obtained on the surface of the first transparent conductive film. In addition, the contact resistance of the first transparent conductive film can be lowered. Further, since the binder resin can protect the metal nanowires, in the present invention, the amount of the binder resin used can be increased (that is, the region composed of the binder resin can be thickened) by containing the metal particles. .. As a result, a first transparent conductive film having excellent scratch resistance can be obtained. By using the first transparent conductive film having excellent scratch resistance as described above, it is possible to obtain a dimming film in which the dimming function is not impaired even when subjected to work involving friction. For example, when the light control film is put into practical use, when the transparent conductive layer is once peeled off to form an electrode on the transparent conductive layer side, there is no problem in wiping work for cleaning the transparent conductive layer, that is, unnecessary. This can be done without causing disconnection of the metal nanowires.

In one embodiment, a part of the conductive particles 23 protrudes from the region composed of the binder resin 21 toward the surface of the first transparent conductive film. That is, in the first transparent conductive film, the conductive particles are exposed on the surface opposite to the transparent substrate. With such a configuration, the above effect becomes remarkable.

The surface resistance value of the first transparent conductive film is preferably 0.1Ω / □ to 1000Ω / □, more preferably 0.5Ω / □ to 300Ω / □, and particularly preferably 1Ω / □ to. It is 200Ω / □.

The haze value of the first transparent conductive film is preferably 20% or less, more preferably 10% or less, and further preferably 0.1% to 5%.

The total light transmittance of the first transparent conductive film is preferably 30% or more, more preferably 35% or more, and particularly preferably 40% or more.

B-1. Transparent Conductive Layer As described above, the transparent conductive layer contains a binder resin, metal nanowires, and conductive particles. In one embodiment, the binder resin is present so as to cover at least a portion of the metal nanowires and the conductive particles, and the region composed of the binder resin can function as a protective layer. Preferably, the conductive particles partially protrude from the region composed of the binder resin. In one embodiment, the transparent conductive layer contains a surface conditioner.

The total light transmittance of the transparent conductive layer is preferably 85% or more, more preferably 90% or more, and further preferably 95% or more.

B-1-1. Binder resin The thickness Y of the region composed of the binder resin is preferably 0.15 μm to 5 μm, more preferably 0.15 μm to 3 μm, and further preferably 0.15 μm to 2 μm. In the present specification, the thickness Y of the region composed of the binder resin is, as shown in FIG. 2, the distance from one flat surface of the transparent conductive layer to the other flat surface, in other words, conductive. It means the thickness of the transparent conductive layer when it is assumed that the protrusions of the sex particles are excluded. In the present invention, since conduction can be ensured by the conductive particles, the region composed of the binder resin can be made relatively thick. As a result, a transparent conductive film having excellent scratch resistance can be obtained.

As the binder resin, any suitable resin can be used. Examples of the resin include acrylic resins; polyester resins such as polyethylene terephthalate; aromatic resins such as polystyrene, polyvinyltoluene, polyvinyl xylene, polyimide, polyamide and polyamideimide; polyurethane resins; epoxy resins; polyolefin resins. Resins; acrylonitrile-butadiene-styrene copolymer (ABS); cellulose; silicon-based resin; polyvinyl chloride; polyacetate; polynorbornene; synthetic rubber; fluororesin and the like.

In one embodiment, a curable resin is used as the binder resin. The curable resin can be obtained from a monomer composition containing a polyfunctional monomer. Examples of the polyfunctional monomer include tricyclodecanedimethanol diacrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane triacrylate, pentaerythritol tetra (meth) acrylate, and dimethylolpropane. Tetra acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol (meth) acrylate, 1,9-nonanediol diacrylate, 1,10-decanediol (meth) acrylate, polyethylene glycol di (meth) acrylate , Polypropylene glycol di (meth) acrylate, dipropylene glycol diacrylate, isocyanuric acid tri (meth) acrylate, ethoxylated glycerin triacrylate, ethoxylated pentaerythritol tetraacrylate and the like. The polyfunctional monomer may be used alone or in combination of two or more.

The monomer composition may further contain a monofunctional monomer. When the monomer composition contains a monofunctional monomer, the content ratio of the monofunctional monomer is preferably 40 parts by weight or less, more preferably 20 parts by weight or less, based on 100 parts by weight of the monomer in the monomer composition. be.

Examples of the monofunctional monomer include ethoxylated o-phenylphenol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, 2-ethylhexyl acrylate, lauryl acrylate, isooctyl acrylate, and isostearyl. Examples thereof include acrylate, cyclohexyl acrylate, isophoronyl acrylate, benzyl acrylate, 2-hydroxy-3-phenoxy acrylate, acryloylmorpholine, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hydroxyethyl acrylamide and the like. .. In one embodiment, a monomer having a hydroxyl group is used as the monofunctional monomer.

B-1-2. Metal nanowires Metal nanowires are conductive substances that are made of metal, have a needle-like or thread-like shape, and have a diameter of nanometers. The metal nanowires may be linear or curved. If a transparent conductive layer made of metal nanowires is used, the metal nanowires form a mesh pattern, so that a good electric conduction path can be formed even with a small amount of metal nanowires, and the transparency has low electrical resistance. A conductive film can be obtained. Further, since the metal nanowires have a mesh shape, an opening can be formed in the gap between the meshes to obtain a transparent conductive film having high light transmittance.

The ratio (aspect ratio: L / d) of the thickness d to the length L of the metal nanowire is preferably 10 to 100,000, more preferably 50 to 100,000, and particularly preferably 100 to 100. It is 10,000. By using metal nanowires having such a large aspect ratio, the metal nanowires can cross well and a small amount of metal nanowires can exhibit high conductivity. As a result, a transparent conductive film having high light transmittance can be obtained. In the present specification, the "thickness of the metal nanowire" means the diameter of the metal nanowire when the cross section is circular, and the minor diameter when the cross section of the metal nanowire is elliptical, and is polygonal. In some cases it means the longest diagonal. The thickness and length of the metal nanowires can be confirmed by a scanning electron microscope or a transmission electron microscope.

The thickness of the metal nanowires is preferably less than 500 nm, more preferably less than 200 nm, particularly preferably 10 nm to 100 nm, and most preferably 10 nm to 50 nm. Within such a range, a transparent conductive layer having high light transmittance can be formed.

The length of the metal nanowires is preferably 1 μm to 1000 μm, more preferably 10 μm to 500 μm, and particularly preferably 10 μm to 100 μm. Within such a range, a transparent conductive film having high conductivity can be obtained.

As the metal constituting the metal nanowire, any suitable metal can be used as long as it is a conductive metal. Examples of the metal constituting the metal nanowire include silver, gold, copper, nickel and the like. Further, a material obtained by plating these metals (for example, gold plating) may be used. Of these, silver, copper or gold is preferable, and silver is more preferable, from the viewpoint of conductivity.

Any suitable method can be adopted as the method for producing the metal nanowires. For example, a method of reducing silver nitrate in a solution, a method of applying an applied voltage or a current to the surface of the precursor from the tip of the probe, pulling out a metal nanowire at the tip of the probe, and a method of continuously forming the metal nanowire can be mentioned. .. In the method of reducing silver nitrate in a solution, silver nanowires can be synthesized by liquid-phase reducing a silver salt such as silver nitrate in the presence of a polyol such as ethylene glycol and polyvinylpyrrolidone. Uniformly sized silver nanowires are available, for example, from Xia, Y. et al. et al. , Chem. Mother. (2002), 14, 4736-4745, Xia, Y. et al. et al. , Nano letters (2003) 3 (7), 955-960, can be mass-produced.

The content ratio of the metal nanowires in the transparent conductive layer is preferably 0.1 part by weight to 50 parts by weight, and more preferably 0.1 parts by weight with respect to 100 parts by weight of the binder resin constituting the transparent conductive layer. It is 30 parts by weight. Within such a range, a transparent conductive film having excellent conductivity and light transmittance can be obtained.

B-1--3. Conductive Particles The conductive particles in the transparent conductive layer may exist as single particles or as aggregates. Further, single particles and aggregates may be mixed.

The average particle size X of the conductive particles and the thickness Y of the region composed of the binder resin preferably satisfy the relationship of Y ≦ X ≦ 20Y, and more preferably the relationship of Y ≦ X ≦ 15Y. , Y ≦ X ≦ 10Y is more preferable. This is because by setting Y ≦ X, a part of the conductive particles protrudes from the region composed of the binder resin and can contribute to the continuity, so that higher conductivity can be ensured. On the other hand, by setting X ≦ 20Y, the conductive particles are well retained in the transparent conductive layer. Further, by setting X ≦ 10Y, the retention of the conductive particles becomes better, and a transparent conductive film having a significantly low resistance can be obtained. In the present specification, when the term "average particle size" is simply used, the "average particle size" refers to the average particle size (primary particle size) of the conductive particles existing as single particles and the conductive particles existing as aggregates. It is a concept including both the average particle size (secondary particle size) of the aggregate. The average particle size and the average primary particle size (described later) of the conductive particles constituting the aggregate are randomly selected from the surface or cross-sectional image of the transparent conductive layer by a microscope (for example, an optical microscope, a scanning electron microscope or a transmission electron microscope). It is a median diameter (50% diameter; number standard) of the particle size (major axis diameter) measured by observing 100 particles extracted in.

The average primary particle size of the conductive particles present in the transparent conductive layer is preferably 5 nm to 100 μm, more preferably 10 nm to 50 μm, and further preferably 20 nm to 10 μm. Within such a range, a transparent conductive layer having excellent conductivity can be formed. Further, by setting the average primary particle size of the conductive particles to 10 μm or less, a transparent conductive film having better scratch resistance can be obtained.

The aspect ratio (ratio of thickness (minor axis diameter) d to length (major axis diameter) L: L / d) of the conductive particles is preferably 2.0 or less, more preferably 1.5. It is as follows. Within such a range, a protruding portion of the conductive particles (a portion protruding from the region composed of the binder resin) can be easily formed.

The content ratio of the conductive particles is preferably 0.1 part by weight to 20 parts by weight, and more preferably 0.2 parts by weight to 10 parts by weight with respect to 100 parts by weight of the binder resin. Within such a range, a transparent conductive film having excellent both conduction and scratch resistance can be obtained. In addition, a transparent conductive film having excellent transparency can be obtained.

Preferably, the conductive particles include a conductive metal. In one embodiment, single-layer metallic particles are used as the conductive particles. In another embodiment, as the conductive particles, metallic particles obtained by coating the surface of any suitable core particles with the conductive metal (for example, plating) are used. Examples of the material constituting the core particles include the above-mentioned conductive metal; insulator particles made of an organic substance or an inorganic substance; and semiconductor particles. As the conductive metal, any suitable metal can be used. Specific examples of the conductive metal include silver, gold, copper, nickel, palladium and the like. As the conductive metal, metallic particles using silver, copper or gold are preferably used, and more preferably, metallic particles using silver are used. Further, as an example of the metallic particles obtained by the coating treatment, silver-coated copper particles can be mentioned. When particles composed of metal oxides are used, sufficient conduction may not be obtained.

B-1-4. Surface conditioner As the surface conditioner, for example, a leveling agent is used. Examples of the leveling agent include an acrylic leveling agent, a fluorine-based leveling agent, and a silicone-based leveling agent. As an acrylic leveling agent, Polyflow No. 36, Polyflow No. 56, Polyflow No. 85HF, Polyflow No. 99C (both manufactured by Kyoeisha Chemical Co., Ltd.) and the like can be mentioned. Examples of the fluorine-based leveling agent include Megafuck F470N and Megafuck F556 (both manufactured by DIC Corporation). Examples of the silicone-based leveling agent include LE303 (manufactured by Kyoeisha Chemical Co., Ltd.) and Grandic PC4100 (manufactured by DIC Corporation).

The content ratio of the surface adjusting agent is preferably 0.1 part by weight to 20 parts by weight, and more preferably 0.5 part by weight to 5 parts by weight with respect to 100 parts by weight of the binder resin.

B-1-5. Method for Forming a Transparent Conductive Layer The transparent conductive layer can be formed, for example, by coating a transparent conductive layer forming composition (RNP) on the transparent substrate. In one embodiment, the transparent conductive layer forming composition comprises a binder resin, metal nanowires and conductive particles.

In another embodiment, a transparent conductive layer forming composition (NP) containing metal nanowires and conductive particles is applied (coated and dried), and then a transparent conductive layer forming composition (R) containing a binder resin is applied. ) Can be applied to form a transparent conductive layer. At this time, the transparent conductive layer forming composition (NP) containing the metal nanowires and the conductive particles may also contain a binder resin, an arbitrary suitable resin capable of improving the dispersion stability, or the like.

In yet another embodiment, the composition for forming a transparent conductive layer (N) containing metal nanowires is applied (coated and dried), and then the composition for forming a transparent conductive layer containing a binder resin and conductive particles ( RP) can be applied to form a transparent conductive layer. At this time, the composition (N) for forming a transparent conductive layer containing the metal nanowires may also contain a binder resin, an arbitrary suitable resin capable of improving the dispersion stability, or the like.

In yet another embodiment, the composition for forming a transparent conductive layer (P) containing conductive particles is applied (coated and dried), and then the composition for forming a transparent conductive layer containing a binder resin and metal nanowires ( RN) can be applied to form a transparent conductive layer. At this time, the composition (P) for forming a transparent conductive layer containing the conductive particles may also contain a binder resin, an arbitrary suitable resin capable of improving the dispersion stability, or the like.

Preferably, the composition for forming a transparent conductive layer (NP, N, RP, P, RN) containing the conductive particles and / or the metal nanowires disperses the metal nanowires and / or the conductive particles in any suitable solvent. It is a dispersion liquid obtained by the above. Examples of the solvent include water, an alcohol solvent, a ketone solvent, an ether solvent, a hydrocarbon solvent, an aromatic solvent and the like.

The dispersion concentration of the metal nanowires in the composition for forming a transparent conductive layer (NP, N, RP, P, RN) containing the metal nanowires is preferably 0.01% by weight to 5% by weight. Within such a range, a transparent conductive layer having excellent conductivity and light transmission can be formed.

The dispersion concentration of the conductive particles in the composition for forming a transparent conductive layer (NP, N, RP, P, RN) containing the conductive particles is preferably 0.001% by weight to 5% by weight. Within such a range, a transparent conductive layer having excellent conductivity and light transmission can be formed.

The composition for forming a transparent conductive layer (NP, N, RP, P, RN) containing the conductive particles and / or the metal nanowires may further contain any suitable additive depending on the purpose. Examples of the additive include a corrosion inhibitor that prevents corrosion of metal nanowires and / or conductive particles, a surfactant that prevents aggregation of metal nanowires, and the like. In addition, the composition for forming a transparent conductive layer includes a plasticizer, a heat stabilizer, a light stabilizer, a lubricant, an antioxidant, an ultraviolet absorber, a flame retardant, a colorant, an antistatic agent, a compatibilizer, a cross-linking agent, and an increase. It may contain additives such as thickeners, inorganic particles, surfactants, and dispersants. Further, the composition (R) for forming a transparent conductive layer containing a binder resin may contain any suitable solvent. The type, number and amount of additives used can be appropriately set according to the purpose.

In one embodiment, the transparent conductive layer forming composition (RNP, NP, R, N, RP, P, RN) contains a surface conditioner. In particular, it is preferable to include a surface conditioner in the composition for forming a transparent conductive layer (RNP, R, RP, RN) containing a binder resin.

The surface conditioner is an additive that adjusts the surface tension of the coating layer. Typical examples of the surface conditioner include a leveling agent. As the leveling agent, the leveling agent described in Section B-1-4 is used.

By including the surface conditioner in the composition for forming the transparent conductive layer, the surface free energy of the transparent conductive layer can be brought close to the surface free energy of the composition for forming the dimming layer. As a result, it is possible to prevent poor coating (so-called repelling) when the dimming layer is formed. In a light control film using a light control layer in which repelling is generated, electrodes may conduct with each other in the repellent portion, which may cause problems such as short circuit. Therefore, the composition for forming a transparent conductive layer contains a surface conditioner. Therefore, the problem can be prevented. When a surface additive is used under the prior art, conduction is hindered by the surface additive, but according to the present invention, the surface additive is formed by forming a transparent conductive layer containing conductive particles. It is possible to remarkably reduce the influence of the above, and it is possible to form a transparent conductive layer in which good continuity is ensured.

The content ratio of the surface conditioner in the composition for forming a transparent conductive layer is preferably 0.1 part by weight to 20 parts by weight, and more preferably 0.5 part by weight to 5 parts by weight with respect to 100 parts by weight of the binder resin. It is a part by weight.

Any suitable method can be adopted as the method for applying the composition for forming the transparent conductive layer. Examples of the coating method include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, letterpress printing method, intaglio printing method, gravure printing method and the like. As a method for drying the coating layer, any suitable drying method (for example, natural drying, blast drying, heat drying) can be adopted. For example, in the case of heat drying, the drying temperature is typically 80 ° C. to 150 ° C., and the drying time is typically 1 to 20 minutes. Further, after coating the transparent conductive layer forming composition (R, RP, RN) containing the binder resin, the coated layer may be subjected to a curing treatment (for example, heat treatment, ultraviolet irradiation treatment).

B-2. Transparent base material Any suitable material can be used as the material constituting the transparent base material. Specifically, for example, a polymer base material such as a film or a plastic base material is preferably used. This is because the transparent base material has excellent smoothness and wettability with respect to the composition for forming a transparent conductive layer, and the productivity can be significantly improved by continuous production by rolls.

The material constituting the transparent substrate is typically a polymer film containing a thermoplastic resin as a main component. Examples of the thermoplastic resin include polyester resins; cycloolefin resins such as polynorbornene; acrylic resins; polycarbonate resins; cellulose resins and the like. Of these, polyester-based resins, cycloolefin-based resins, or acrylic-based resins are preferable. These resins are excellent in transparency, mechanical strength, thermal stability, moisture shielding property and the like. The above thermoplastic resin may be used alone or in combination of two or more. Further, it is also possible to use an optical film such as that used for a polarizing plate, for example, a low retardation base material, a high retardation base material, a retardation plate, a luminance improving film, or the like as a base material.

The thickness of the transparent substrate is preferably 20 μm to 200 μm, and more preferably 30 μm to 150 μm.

The total light transmittance of the transparent substrate is preferably 30% or more, more preferably 35% or more, and further preferably 40% or more.

C. Second Transparent Conductive Film As the second transparent conductive film, any suitable transparent conductive film can be used as long as the dimming function of the dimming film can be exhibited. Preferably, as the second transparent conductive film, the transparent conductive film as described in Section B above is used. In this case, the second conductive film is preferably arranged with the transparent conductive layer on the dimming layer side, and more preferably arranged so that the transparent conductive layer and the dimming layer are in contact with each other. In another embodiment, a transparent conductive film containing a metal oxide such as indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO2) and the like can be used.

D. Dimming layer In one embodiment, the dimming layer contains a liquid crystal compound. The dimming layer containing the liquid crystal compound is configured by dispersing the liquid crystal compound in the resin matrix. In the dimming layer, the degree of orientation of the liquid crystal compound can be changed depending on the presence or absence of voltage application, and the transmission mode and the scattering mode can be switched. In one embodiment, the transmission mode is set when a voltage is applied, and the scattering mode is set when no voltage is applied (normal mode). In this embodiment, when no voltage is applied, the liquid crystal compound is not oriented and the scattering mode is set, and when the voltage is applied, the liquid crystal compound is oriented and the transmission mode is set. In another embodiment, the scattering mode is set when a voltage is applied, and the transmission mode is set when no voltage is applied (reverse mode). In this embodiment, the liquid crystal compound is oriented when no voltage is applied, and the oriented liquid crystal compound exhibits a refractive index substantially the same as that of the resin matrix, and is in the transmission mode. On the other hand, when a voltage is applied, the orientation of the liquid crystal compound is disturbed and the scattering mode is established.

Examples of the dimming layer as described above include a dimming layer including a polymer-dispersed liquid crystal display, a dimming layer including a polymer network type liquid crystal display, and the like. The polymer-dispersed liquid crystal has a structure in which the liquid crystal is phase-separated in the polymer. The polymer network-type liquid crystal has a structure in which the liquid crystal is dispersed in the polymer network, and is in the polymer network. The liquid crystal of the above has a continuous phase.

As the liquid crystal compound, any suitable non-polymerized liquid crystal compound is used. Examples thereof include nematic type, smectic type and cholesteric type liquid crystal compounds. It is preferable to use a nematic liquid crystal compound because excellent transparency can be realized in the transmission mode. Examples of the nematic liquid crystal compound include biphenyl compounds, phenylbenzoate compounds, cyclohexylbenzene compounds, azoxybenzene compounds, azobenzene compounds, azomethine compounds, terphenyl compounds, biphenylbenzoate compounds, and cyclohexyl biphenyl compounds. , Phenylpyridine compounds, cyclohexylpyrimidine compounds, cholesterol compounds and the like.

The content of the liquid crystal compound in the light control layer is, for example, 40% by weight or more, preferably 50% by weight to 70% by weight.

The resin forming the resin matrix constituting the light control layer can be appropriately selected depending on the light transmittance, the refractive index of the liquid crystal compound, and the like. The resin is typically an active energy ray-curable resin, and liquid crystal polymers, (meth) acrylic resins, silicone resins, epoxy resins, fluororesins, polyester resins, polyimide resins and the like are preferably used. obtain.

The content of the resin matrix in the light control layer is 60% by weight or less, preferably 30% by weight to 50% by weight. If the content of the resin matrix is less than 30% by weight, problems such as low adhesion to the substrate may occur. On the other hand, if the content of the first polymer exceeds 60% by weight, problems such as an increase in driving voltage and a decrease in dimming function may occur.

The dimming layer containing the liquid crystal compound can be formed by any suitable method. In the dimming layer, for example, a dimming layer forming composition is applied to the transparent electrode layer side of one substrate to form a coating layer, and the transparent electrode layer faces the other substrate on the coating layer. It can be obtained by laminating in this way to form a laminated body a and curing the coating layer. At this time, the composition for forming a light control layer contains, for example, a monomer for forming a resin matrix (preferably an active energy ray-curable monomer) and a liquid crystal compound.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The evaluation method in the examples is as follows. The thickness was measured by using a scanning electron microscope "S-4800" manufactured by Hitachi High-Technologies Corporation to form a cross section by embedding with an epoxy resin and then cutting with an ultramicro tome.

(1) Contact angle The contact angle of the dimming layer forming composition with respect to the transparent conductive layer was measured by the following method. A water droplet having a diameter of 1.5 mm was formed on the needle tip, and the water droplet was brought into contact with the surface of the transparent conductive layer, and the static contact angle between the water droplet and the transparent conductive layer was measured with a contact angle meter (manufactured by Kyowa Surface Chemistry Co., Ltd.).
(2) Measurement of size of metal nanowires and conductive particles Olympus optical microscope "BX-51", Hitachi High-Technologies scanning electron microscope "S-4800" and Hitachi High-Technologies electric field emission transmission It was measured using an electron microscope "HF-2000". The average particle size was defined as the median diameter (50% diameter; number standard) of the particle size measured by observing 100 particles randomly extracted on the surface or cross section of the transparent conductive layer with the microscope.
(3) Surface resistance value The surface resistance value of the transparent conductive film was measured by an eddy current method using a non-contact surface resistance tester trade name "EC-80" manufactured by Napson Corporation. The measurement temperature was 23 ° C.
(4) Haze value The haze value of the transparent conductive film was measured by the following method.
A transparent conductive film was attached to the glass with an adhesive, and the measurement was performed at 23 ° C. using the trade name "HR-100" manufactured by Murakami Color Research Institute.
(5) Projection height Measured according to JIS B 0031: 2001 using a nanoscale hybrid microscope (product name: VN-8000) manufactured by KEYENCE. The ten-point average roughness Rz having a measurement area of 200 μm □ was defined as the protrusion height.
(6) Scratch resistance The scratch resistance of the transparent conductive layer of the transparent conductive film was evaluated under the condition that steel wool # 0000 was used and a probe having a radius of 25 mm was reciprocated at a length of 10 cm × 10 with a load of 300 g. When the number of scratches visually confirmed in the central portion (25 mm × 25 mm) was 10 or less, it was accepted, and when it exceeded 10, it was rejected.
(7) Conduction of transparent conductive film A silver paste line (length 20 mm x width 1 mm) is applied on the protective layer at predetermined intervals (5 mm, 15 mm and 35 mm), and the resistance value between the two points is Sanwa. The measurement was performed using the trade name "Digital Multimeter CD800a" manufactured by Electric Instrument Co., Ltd. The linear form was obtained from the correlation between the distance between the two points and the resistance value, the value obtained by dividing the intercept by 2 was calculated as the contact resistance value, and when it was 10 Ω or less, the continuity was marked as ◯.
(8) Driving the light control film After removing the light control layer at the end of the light control film by rubbing it with degreased cotton soaked in ethanol, a conductive copper foil adhesive tape (manufactured by Teraoka Seisakusho, trade name "" No. 8323 ") was applied to the portion from which the light control layer was removed, and a voltage was applied to evaluate the driveability of the light control film according to the following evaluation criteria.
〇: Drives normally △: Drives, but overcurrent flows in part and discolors ×: Does not drive

[Production Example 1] Preparation of composition (N) for forming a transparent conductive layer Chem. Mother. Silver nanowires were synthesized according to the method described in 2002, 14, 4736-4745. The obtained silver nanowires had a diameter of 10 nm to 60 nm and a length of 1 μm to 50 μm. The size of the silver nanowires was measured by observing 30 metal nanowires randomly selected by the scanning electron microscope "S-4800" manufactured by Hitachi High-Technologies Corporation and measuring the length and diameter. ..
The silver nanowires obtained above are dispersed in pure water to a concentration of 0.2% by weight and dodecyl-pentaethylene glycol at a concentration of 0.1% by weight to form a transparent conductive layer (N). Got

[Production Example 2] Preparation of composition for forming a transparent conductive layer (RP-1) 100 parts by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat # 300") and a photopolymerization initiator (BASF) 5 parts by weight of conductive particles (silver particles; product name "SPN08S" manufactured by Mitsui Kinzoku Co., Ltd., average primary particle size: 1.7 μm), 2.5 parts by weight, surface conditioner (Silicone-based leveling agent, manufactured by Kyoeisha Chemical Co., Ltd., trade name "LE303") 1 part by weight is diluted with methylisobutylketone to form a transparent conductive layer having a solid content concentration of 17% by weight (RP-1). Got

[Production Example 3] Preparation of composition for forming a transparent conductive layer (RP-2) The composition for forming a transparent conductive layer (RP-2) is the same as in Production Example 2 except that a surface conditioner is not added. ) Was obtained.

[Production Example 4] Preparation of composition for forming a transparent conductive layer (R-1) A composition for forming a transparent conductive layer in the same manner as in Production Example 2 except that conductive particles and a surface modifier were not added. (R-1) was obtained.

[Production Example 5] Preparation of Transparent Conductive Layer Forming Composition (R-2) The transparent conductive layer forming composition (R-2) is the same as in Production Example 2 except that conductive particles are not added. ) Was obtained.

[Example 1]
(Formation of transparent conductive film)
A PET film (manufactured by Mitsubishi Plastics, trade name "S100") was used as the transparent substrate. The transparent conductive layer forming composition (N) prepared in Production Example 1 was applied onto this transparent substrate using a bar coater (manufactured by Daiichi Rika Co., Ltd., product name “Barcoater No. 16”). It was dried for 2 minutes in a blower dryer at 120 ° C. Then, the composition for forming a transparent conductive layer (RP-1) prepared in Production Example 2 was applied with a slot die at a Wet film thickness of 6 μm, and dried in a blower dryer at 80 ° C. for 2 minutes.
Next, the composition for forming a transparent conductive layer (RP-1) is cured and protected by irradiating ultraviolet light with an ^{integrated illuminance of 210 mJ / cm 2} with an ultraviolet light irradiation device (manufactured by Fusion UV Systems) in an environment with an oxygen concentration of 100 ppm. A layer was formed to obtain a transparent conductive film A (a transparent conductive layer containing silver nanowires, silver particles and a surface conditioner).
In the transparent conductive film A, the thickness Y of the region composed of the binder resin (referred to as the film thickness of the transparent conductive layer in Table 1 for convenience) is 1 μm, and the height Z of the protruding portion of the conductive particles is It was 0.7 μm. Further, the surface resistance value of the transparent conductive film A was 50Ω / □, the haze value was 2.9%, the scratch resistance was acceptable, and the conduction was well secured.

(Formation of dimming film)
As the first transparent conductive film and the second transparent conductive film, two transparent conductive films A were prepared. A dimming layer containing a nematic liquid crystal and a urethane resin is formed on the transparent conductive layer of the transparent conductive film A using a bar coater (manufactured by Daiichi Rika Co., Ltd., product name "Barcoater No. 24"). The composition was applied and dried at room temperature for 30 minutes to form a dimming layer. The contact angle of the light control layer forming composition with respect to the transparent conductive layer was 29 °, and no repelling was confirmed when the light control layer forming composition was applied.
Next, the transparent conductive layer side of the other transparent conductive film A was bonded to the dimming layer to obtain a dimming film. The obtained light control film was subjected to the above evaluation (8). The results are shown in Table 1.

[Example 2]
(Formation of transparent conductive film)
The transparent conductive layer is formed in the same manner as in Example 1 except that the transparent conductive layer forming composition (RP-2) prepared in Production Example 3 is used instead of the transparent conductive layer forming composition (RP-1). A sex film B (a transparent conductive layer containing silver nanowires and silver particles) was obtained.
In the transparent conductive film B, the thickness Y of the region composed of the binder resin (referred to as the film thickness of the transparent conductive layer in Table 1 for convenience) is 1 μm, and the height Z of the protruding portion of the conductive particles is It was 0.7 μm. Further, the surface resistance value of the transparent conductive film B was 50Ω / □, the haze value was 5.1%, the scratch resistance was acceptable, and the continuity was well secured.

(Formation of dimming film)
A dimming film was obtained in the same manner as in Example 1 except that the transparent conductive film B was used instead of the transparent conductive film A for both the first transparent conductive film and the second transparent conductive film. rice field. The contact angle of the light control layer forming composition with respect to the transparent conductive layer was 75 °, and repelling was confirmed when the light control layer forming composition was applied. The obtained light control film was subjected to the above evaluation (8). The results are shown in Table 1.

[Comparative Example 1] (Formation of transparent conductive film)
Instead of the transparent conductive layer forming composition (RP-1), the transparent conductive layer forming composition (R-1) prepared in Production Example 4 is used, and the transparent conductive layer forming composition (R-1) is applied. A transparent conductive film C (a transparent conductive layer containing silver nanowires) was obtained in the same manner as in Example 1 except that the Wet film thickness at the time was 0.9 μm.
In the transparent conductive film C, the thickness Y of the region composed of the binder resin (referred to as the film thickness of the transparent conductive layer in Table 1 for convenience) was 0.15 μm. The scratch resistance was unacceptable and continuity was ensured.

(Formation of dimming film)
A dimming film was obtained in the same manner as in Example 1 except that the transparent conductive film C was used instead of the transparent conductive film A for both the first transparent conductive film and the second transparent conductive film. rice field. The contact angle of the light control layer forming composition with respect to the transparent conductive layer was 50 °, and repelling was confirmed when the light control layer forming composition was applied. The obtained light control film was subjected to the above evaluation (8). The results are shown in Table 1.

[Comparative Example 2] (Formation of transparent conductive film)
The transparent conductive layer is formed in the same manner as in Example 1 except that the transparent conductive layer forming composition (R-2) prepared in Production Example 5 is used instead of the transparent conductive layer forming composition (RP-1). A sex film D (a transparent conductive layer containing silver nanowires and a surface conditioner) was obtained.
In the transparent conductive film D, the thickness Y of the region composed of the binder resin (referred to as the film thickness of the transparent conductive layer in Table 1 for convenience) was 0.15 μm. The scratch resistance was unacceptable and continuity was not ensured.

(Formation of dimming film)
A dimming film was obtained in the same manner as in Example 1 except that the transparent conductive film D was used instead of the transparent conductive film A for both the first transparent conductive film and the second transparent conductive film. rice field. The contact angle of the light control layer forming composition with respect to the transparent conductive layer was 30 °, and no repelling was confirmed when the light control layer forming composition was applied. The obtained light control film was subjected to the above evaluation (8). The results are shown in Table 1.

[Comparative Example 3]
A transparent electric film E was obtained in the same manner as in Comparative Example 1 except that the thickness Y of the region composed of the binder resin was 1 μm. In the transparent conductive film E, the scratch resistance was acceptable, and the continuity was not ensured.
A dimming film was obtained in the same manner as in Example 1 except that the transparent conductive film E was used instead of the transparent conductive film A for both the first transparent conductive film and the second transparent conductive film. rice field. The contact angle of the light control layer forming composition with respect to the transparent conductive layer was 54 °, and repelling was confirmed when the light control layer forming composition was applied. The obtained light control film was subjected to the above evaluation (8). The results are shown in Table 1.

As is clear from the results of Examples and Comparative Examples, the light control film of the present invention has excellent scratch resistance of the transparent conductive film, and is good even after being subjected to the electrode arrangement operation (evaluation (8)). Driven to. On the other hand, as a result of the electrode arrangement operation (evaluation (8)), the transparent conductive layer of the light control film provided with the transparent conductive film containing no conductive particles was damaged and could not be driven satisfactorily (Comparative Example 1). 2). In a light control film provided with a transparent conductive film that does not contain conductive particles, scratch resistance can be improved by increasing the thickness of the transparent conductive layer, but in that case, there arises a problem that conduction is not ensured. (Comparative example 3).

In Comparative Example 2, it is an experimental example using a composition for forming a transparent conductive layer containing a surface preparation agent, but in this case, it was confirmed that the conduction was not sufficient. It is considered that this is because the surface conditioner inhibits the continuity. On the other hand, in Example 1, by incorporating the surface preparation agent into the composition for forming the transparent conductive layer, it is possible to form a coating layer having a good surface condition at the time of coating the composition for forming a dimming layer. As a result, a dimming film that is difficult to short-circuit can be obtained, and continuity is ensured. In the present invention, since the conductive particles are contained, the influence of the surface preparation agent is suppressed, and a light control film having a transparent conductive layer having excellent conductivity can be obtained.

10 Transparent base material 20 Transparent conductive layer 21 Resin binder 22 Metal nanowires 23 Conductive particles 110 First transparent conductive film 120 Dimming layer 130 Second transparent conductive film

Claims (6)

A first transparent conductive film, a dimming layer, and a second transparent conductive film are provided in this order.
The first transparent conductive film comprises a transparent substrate and transparent conductive layers arranged on both sides or one side of the transparent substrate.
Transparent conductive layer, seen containing a binder resin, and the metal nanowires, and conductive particles,
The average particle size X of the conductive particles and the thickness Y of the region composed of the binder resin satisfy the relationship of Y ≦ X ≦ 20Y.
Dimming film. The light control film according to claim 1, wherein the light control layer contains a liquid crystal compound. The dimming film according to claim 1 or 2, wherein the average primary particle size of the conductive particles is 5 nm to 100 μm. The dimming film according to any one of claims 1 to 3 , wherein the content ratio of the conductive particles is 0.1 part by weight to 20 parts by weight with respect to 100 parts by weight of the binder resin. The light control film according to any one of claims 1 to 4 , wherein the conductive particles are silver particles. The light control film according to any one of claims 1 to 5 , wherein the transparent conductive layer further contains a surface conditioner.

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