JP7019315B2 - Manufacturing method of dimming film - Google Patents

Description

The present invention relates to a method for producing a light control film.

Conventionally, a polymer-dispersed liquid crystal element (PDLC dimming film) having a dimming function utilizing a light scattering effect due to a composite of a polymer and a liquid crystal material is known (for example, Patent Documents 1 and 2). In the polymer-dispersed liquid crystal element, 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 to make the liquid crystal. By changing the orientation of the 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 polymer-dispersed liquid crystal element is usually configured by holding a light control layer containing the composite with a transparent conductive film.

As a method for producing a composite of a polymer and a liquid crystal material, a phase separation method for forming a phase-separated state between the liquid crystal material and a matrix polymer, and an emulsion method for applying a coating liquid containing an emulsified liquid crystal material and a resin. Etc. (for example, Patent Documents 1, 3, and 4).

In the emulsion method, since liquid crystal droplets having a predetermined size (for example, a diameter of 1 μm to 10 μm) are present in the coating liquid in advance, a desired dimming layer can be easily formed. The emulsion method also has the advantage of being suitable for roll-to-roll processes. On the other hand, when a coating liquid in which both the liquid crystal material and the resin are emulsified is used, there is a problem that high-speed coating is difficult and the thickness of the coating layer becomes non-uniform.

Special Table No. 58-501631 Japanese Unexamined Patent Publication No. 60-502128 Japanese Unexamined Patent Publication No. 60-252687 Special Table No. 11-500757 Gazette

When the dimming layer is formed by the emulsion method, the inventors of the present invention tend to have an appearance defect in which the light scattering property becomes abnormal, and the cause is uneven thickness. I found it. Further, the part where the light scattering property becomes abnormal is the surface on the back surface of the transparent conductive film (that is, the surface opposite to the coated surface of the transparent conductive film) when the coating liquid is applied to the transparent conductive film. It was found that it corresponds to the place where a very small foreign substance was present between the transparent conductive film and the carrier (for example, the back roll).

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing a light control film, which comprises forming a light control layer having a uniform thickness by an emulsion method. There is something in it.

The method for producing a light control film of the present invention is a method for manufacturing a light control film, which comprises a coating step of applying a coating liquid containing a liquid crystal compound and a resin to a transparent conductive film using a slot die. The line speed in the coating process is 2 m / min or more, the gap between the lip tip of the slot die and the transparent conductive film is 100 μm or more, and the dimming film is scattered in the transmission mode. It can be switched to and from the mode, and the haze value in the scattering mode of the light control film is 80% or more.
In one embodiment, the slot die has a lip width of 2 mm or less.
In one embodiment, the thickness of the transparent conductive film is 10 μm to 200 μm.
In one embodiment, the total amount of the liquid crystal compound and the resin is 30 parts by weight to 70 parts by weight with respect to 100 parts by weight of the coating liquid.
In one embodiment, the viscosity of the coating liquid is 20 mPas to 400 mPas at the time of discharging from the slot die.

According to the present invention, a dimming layer having a uniform thickness is formed by applying a coating liquid using a slot die and setting the gap between the slot die and the coating base material (transparent conductive film) to 100 μm or more. Can be formed. According to the present invention, even when a coating liquid containing an emulsified liquid crystal material and a resin is used as the coating liquid, a dimming layer having a uniform thickness can be formed. The dimming layer formed by the present invention can prevent the occurrence of an abnormal light scattering property and has an excellent appearance.

It is the schematic sectional drawing of the light control film manufactured by the manufacturing method by one Embodiment of this invention. It is a schematic cross-sectional view which shows the vicinity of the lip of a slot die in the coating process of this invention. It is the schematic sectional drawing of the 1st transparent conductive film by one Embodiment of this invention.

A. Outline of Method for Manufacturing Light Control Film The method for manufacturing a light control film of the present invention includes a coating step of applying a coating liquid containing a liquid crystal compound and a resin to a transparent conductive film using a slot die. In the coating process, the gap between the lip tip of the slot die and the transparent conductive film is 100 μm or more. The line speed in the coating process is 2 m / min or more. In the above coating liquid, both the liquid crystal compound and the resin are emulsified. In one embodiment, in the coating process, a coating liquid is applied to a first transparent conductive film to form a dimming layer, and then a second transparent conductive film is bonded to the dimming layer. A dimming film can be obtained.

FIG. 1 is a schematic cross-sectional view of a light control film manufactured by the manufacturing method 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 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.

The light control film produced by the production method of the present invention has a haze value of 80% or more, preferably 80% to 99%, and more preferably 90% to 99% in the scattering mode. The haze value is measured according to JIS7136.

The haze value of the light control film in the transmission mode is preferably less than 50%, more preferably 20% or less, still more preferably 10% or less. The lower limit of the haze value in the transmission mode is, for example, 1%.

As described above, in the production method of the present invention, a coating liquid containing an emulsified liquid crystal compound and a resin is used. In the coating liquid, the liquid crystal compound is present in a droplet state having a predetermined size (for example, a diameter of 1 μm to 10 μm). By using such a coating liquid, a desired dimming layer can be easily formed, and a dimming layer can be easily formed by a roll-to-roll process. On the other hand, when the emulsified coating liquid is used, the line speed at the time of coating is increased (2 m / min or more), and the haze value in the scattering mode is high (80% or more). ) The inventors of the present invention have found that when a dimming film is obtained, appearance defects (locations where the light scattering property becomes abnormal) tend to occur. As a result of diligent studies by the inventors, it is speculated that the partial thickness variation of the coating layer is the cause of the appearance defect, and the defect due to the thickness variation is more easily visible as the haze value of the light control film is higher. Do you get it. The thickness variation of the coating layer is the back surface of the transparent conductive film as the coating base material (that is, the surface opposite to the coating surface of the transparent conductive film, and the transparent conductive film and the carrier (for example, back roll). It is thought that it is triggered by a very small foreign substance existing between) and). Further, as one of the causes of the thickness variation of the coating layer, the partial thickness variation of the transparent conductive film can be mentioned.

The details of the mechanism inferred for the occurrence of appearance defects are as follows. When an emulsified coating liquid is applied to a transparent conductive film at a predetermined speed or higher using a slot die, between the slot die discharge port and the transparent conductive film in a portion where extremely minute foreign substances are present. The distance becomes closer momentarily. Due to such a momentary fluctuation, the bead (pool) of the coating liquid is disturbed in the vicinity of the lip on the upstream side and / or the downstream side (particularly the downstream side) of the slot die, and the disturbed state continues for a predetermined time. .. It is considered that the thickness of the coating layer fluctuates until this disordered state converges and the bead stabilizes again. It is considered that this thickness variation causes an appearance defect that is significantly larger than the size of the foreign matter. Such a phenomenon does not occur when a normal coating liquid (non-emulsified coating liquid, for example, an organic solvent-based coating liquid) is used, and when an emulsified coating liquid is used. It is considered to be a peculiar phenomenon.

The present invention is an invention that solves the above-mentioned novel problem by setting the gap between the lip tip of the slot die and the transparent conductive film to 100 μm or more. FIG. 2 is a schematic cross-sectional view showing the vicinity of the lip of the slot die in the coating process of the present invention. In FIG. 2, the coating liquid is applied on the transparent conductive film 110 conveyed on the conveying body (back roll) 300 by using the slot die 200. The gap between the tip 211 of the lip 210 of the slot die 200 and the transparent conductive film 110 corresponds to the gap L in FIG. The gap between the tip of the lip of the slot die and the transparent conductive film is a gap measured in a state where there is no foreign matter or the like on the back surface of the transparent conductive film. In the present invention, by setting the gap L to 100 μm or more, it is possible to prevent the bead (liquid pool) of the coating liquid from being disturbed, and it is possible to form a coating layer having excellent thickness uniformity. As a result, it is possible to prevent the occurrence of appearance defects (locations where the light scattering property becomes abnormal). The gap L between the lip tip of the slot die and the transparent conductive film is preferably 100 μm to 550 μm, and more preferably 100 μm to 350 μm.

B. Coating process The coating process is a step of coating (applying / drying) a coating liquid containing an emulsified liquid crystal compound and a resin on one of a pair of transparent conductive films constituting the light control film. Is. Through the coating step, it is possible to obtain a dimming layer in which the liquid crystal compound is dispersed and present in the resin matrix.

(Coating liquid)
The coating liquid can be prepared by any suitable method. For example, it can be obtained by mixing and stirring a liquid crystal compound and a water-soluble polymer (aqueous phase) or resin emulsion (latex) dissolved in water. Details of the method for preparing the coating liquid containing the emulsified liquid crystal compound and the resin are described in, for example, Japanese Patent Laid-Open No. 58-501631, Japanese Patent Application Laid-Open No. 60-2526887, Japanese Patent Application Laid-Open No. 11-500757 and the like. ing. The entire description of the publication is incorporated herein by reference.

As the liquid crystal compound contained in the coating liquid, any suitable liquid crystal compound can be 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.

As the resin contained in the coating liquid, any suitable resin can be used. For example, polyurethane resin, polyethylene resin, polypropylene resin, polyacrylic resin and the like can be mentioned. Further, a copolymer such as a methacrylate / acrylonitrile copolymer, a urethane / acrylate copolymer, or an acrylate / acrylonitrile copolymer may be used.

The total amount of the liquid crystal compound and the resin is preferably 30 parts by weight to 70 parts by weight, and more preferably 40 parts by weight to 60 parts by weight with respect to 100 parts by weight of the coating liquid. Within such a range, a stable emulsion coating liquid can be obtained.

The weight ratio (resin / liquid crystal compound) of the liquid crystal compound to the resin is preferably 10/90 to 90/10, more preferably 30/70 to 70/30. If the proportion of the liquid crystal compound is too large, the liquid crystal emulsion may not be stable and the droplet size may easily become coarse over time. On the other hand, if the proportion of the liquid crystal compound is too small, the dimming function of the dimming film may not be sufficiently exhibited.

The coating liquid may further contain a cross-linking agent. If a coating liquid containing a cross-linking agent is used, a dimming layer composed of a resin matrix having a cross-linked structure can be formed. As the cross-linking agent, any suitable cross-linking agent can be used. For example, an aziridine-based cross-linking agent, an isocyanate-based cross-linking agent, and the like can be mentioned. The content ratio of the cross-linking agent is preferably 0.5 parts by weight to 10 parts by weight, and more preferably 0.8 parts by weight to 5 parts by weight with respect to 100 parts by weight of the coating liquid.

The viscosity of the coating liquid is preferably 20 mPas to 400 mPas, more preferably 30 mPas to 300 mPas, and further preferably 40 mPas to 200 mPas at the time of discharging from the slot die. In the present invention, a particularly excellent effect can be obtained when a coating liquid having a viscosity in such a range is used. If the viscosity is less than 20 mPas, convection of the solvent becomes remarkable when the solvent (water) is dried, and the thickness of the light control layer may become unstable. Further, when the viscosity exceeds 400 mPas, the bead of the coating liquid may not be stable. The viscosity of the coating liquid can be measured by the Leometer MCR302 manufactured by Anton Pearl Co., Ltd. As the viscosity here, the value of the shear viscosity under the conditions of 20 ° C. and a shear rate of 1000 (1 / s) is used.

(Applying coating liquid)
The coating liquid is applied using a slot die. More specifically, the coating liquid is applied by discharging the coating liquid from the slot die while transporting the transparent conductive film on the carrier to form a coating layer on the transparent conductive film. I can be. Any suitable carrier can be used as the carrier for transporting the transparent conductive film. Preferably, the coating liquid is applied while the transparent conductive film is rolled and conveyed. The gap L between the lip tip of the slot die and the transparent conductive film is 100 μm or more as described above.

The ratio (L / T) of the gap L to the thickness (wet thickness, thickness T in FIG. 2) T of the coating layer is preferably 1.5 to 20, and more preferably 1.7 to 15. , More preferably 2 to 13. Within such a range, the effect of the present invention becomes remarkable.

The lip width of the slot die (width W1 in FIG. 2) is preferably 5 mm or less, more preferably 2 mm or less. Within such a range, it is possible to prevent the bead of the coating liquid from being disturbed, and even if the bead is disturbed, the disordered state is eliminated in a short time, so that the thickness uniformity is excellent. A coating layer can be formed. The end face 211 of the lip of the slot die is preferably substantially perpendicular to the discharge direction D. Further, the slot die may be configured such that the end face of the upstream lip and the end face of the downstream side are in the same plane, and the upstream lip and the downstream lip are configured to have a step. May be good. Preferably, as shown in FIG. 2, the end face of the upstream lip and the end face of the downstream side are configured to be in the same plane. Further, when the upstream lip and the downstream lip are configured to have a step, the gap L means the distance between the lip tip closest to the transparent conductive film and the transparent conductive film.

The opening width of the slot die (width W2 in FIG. 2) is preferably 0.1 mm to 5 mm, more preferably 0.1 mm to 2 mm.

The slot die is made of any suitable material. Examples of the material constituting the slot die include iron, stainless steel, nickel-coated iron and the like.

The slot die may be arranged so that the discharge direction D has a predetermined angle with respect to the coated surface. The angle formed by the discharge direction D of the slot die and the coated surface is preferably 70 ° to 110 °, more preferably 80 ° to 100 °. When the transparent conductive film is transported by roll, the coated surface is a surface (tangent plane) perpendicular to the discharge direction when the radial direction of the transport roll and the discharge direction coincide with each other.

The discharge amount of the coating liquid can be set to an arbitrary appropriate discharge amount according to the desired coating layer thickness, coating layer width, line speed, and the like.

The line speed at which the coating liquid is applied is 2 m / min or more, preferably 2 m / min to 50 m / min. Such a line speed is a line speed at which the bead of the coating liquid is likely to be disturbed. However, according to the present invention, even if the coating liquid is applied at a line speed within the above range, the bead of the coating liquid is easily generated. It is possible to prevent the disturbance of the coating layer and form a coating layer having excellent thickness uniformity. Further, if the line speed is in the above range, the dimming layer can be efficiently formed.

The coating liquid may be applied while reducing the pressure. Preferably, the pressure is reduced from the upstream side in the line direction. The degree of decompression is preferably 0.05 kPa to 5 kPa, more preferably 0.1 kPa to 2 kPa, with respect to atmospheric pressure. By applying the coating liquid while reducing the pressure, the beads can be stabilized and a coating layer having excellent thickness uniformity can be formed.

The thickness T of the coating layer is preferably 10 μm to 100 μm, more preferably 20 μm to 100 μm. Within such a range, it is possible to obtain a dimming layer that exhibits a high haze value in the scattering mode and has excellent thickness uniformity.

(Drying of coating layer)
After applying the coating liquid, the coating layer is dried by any suitable method to form a dimming layer. As the drying method, any suitable method can be adopted. For example, heat drying, hot air drying and the like can be mentioned. In one embodiment, when the coating liquid contains a cross-linking agent, a cross-linked structure of the resin matrix is formed in the drying step. The drying temperature is preferably 30 ° C to 80 ° C, more preferably 35 ° C to 60 ° C. The drying time is preferably 1 minute to 15 minutes, more preferably 2 minutes to 10 minutes. By appropriately setting the drying temperature and the drying time, a dimming layer having excellent thickness accuracy can be obtained.

B. Light control film As described above, in one embodiment, the light control film obtained by the production method of the present invention includes a first transparent conductive film, a light control layer, and a second transparent conductive film. Prepare in this order.

The thickness of the light control film is preferably 110 μm to 440 μm, and more preferably 150 μm to 400 μm.

(Transparent conductive film)
FIG. 3 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 second transparent conductive film, like the first transparent conductive film, may include a transparent substrate and transparent conductive layers arranged on both sides or one side of the transparent substrate. The first transparent conductive film and the second transparent conductive film may have the same configuration or may have different configurations. It is preferable that the first transparent conductive film and the second transparent conductive film are arranged so that their respective transparent conductive layers face each other. Hereinafter, the first transparent conductive film and the second transparent conductive film may be collectively referred to as a transparent conductive film.

The thickness of the transparent conductive film is preferably 10 μm to 200 μm, more preferably 20 μm to 200 μm. Within such a range, it is possible to obtain a light control film that is difficult to buckle and has few defects due to buckling. When the coating liquid is applied to a thick film, the influence of foreign matter caught in the film tends to appear. However, according to the production method of the present invention, the coating liquid is applied to a relatively thick transparent conductive film. It is possible to obtain a dimming film with less determination of appearance without being affected by foreign matter even if it is coated with. On the other hand, a transparent conductive film having a thickness of more than 200 μm is disadvantageous in that it is difficult to carry the roll.

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

The haze value of the 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 transparent conductive film is preferably 30% or more, more preferably 60% or more, and particularly preferably 80% or more.

The transparent conductive layer can be formed by using, for example, a metal oxide such as indium tin oxide (ITO), zinc oxide (ZnO), and tin oxide (SnO ₂ ). Alternatively, the transparent conductive layer may be formed of metal nanowires such as silver nanowires (AgNW), carbon nanotubes (CNTs), organic conductive films, metal layers or laminates thereof. The transparent conductive layer can be patterned into a desired shape depending on the purpose.

Any suitable material can be used as the material constituting the transparent substrate. Specifically, for example, a polymer base material such as a film or a plastic base material is preferably used. This is because it is excellent in smoothness and wettability to the composition for forming a transparent conductive layer, and 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, and 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 50 μm to 200 μm, and more preferably 60 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.

(Dimming layer)
In one embodiment, the dimming layer comprises a liquid crystal compound. The dimming layer containing the liquid crystal compound is configured by dispersing the liquid crystal compound in the resin matrix. The dimming layer can be formed by the method described in Section A above.

Examples of the light control layer as described above include a light control layer including a light control layer including a polymer-dispersed liquid crystal display. The polymer-dispersed liquid crystal is composed of a liquid crystal compound present in a droplet state in the polymer.

The liquid crystal compound droplets in the light control layer preferably have a diameter of 1 μm to 10 μm, and more preferably 2 μm to 7 μm.

The liquid crystal compound is not particularly limited, and the liquid crystal compound described in Section A can be used.

The content of the liquid crystal compound in the light control layer is preferably 10 parts by weight to 90 parts by weight, and more preferably 30 parts by weight to 70 parts by weight with respect to 100 parts by weight of the light control layer.

The resin forming the resin matrix constituting the light control layer is not particularly limited, and for example, the resin matrix is formed by the resin described in Section A.

The content of the resin matrix in the light control layer is preferably 10 parts by weight to 90 parts by weight, and more preferably 30 parts by weight to 70 parts by weight with respect to 100 parts by weight of the light control layer.

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.

[Manufacturing Example 1]
(Preparation of coating liquid)
50 parts by weight of an aqueous aliphatic polyurethane latex (manufactured by Geneca, trade name "Neorez R-967", including 35% by weight of latex particles) is added to 50 parts by weight of a liquid crystal compound (manufactured by Chisso, trade name "JM1000XX"). Then, while maintaining the stirring portion at 40 ° C., stirring was performed using an Excel autohomogenizer (manufactured by Nippon Seiki Co., Ltd.) to obtain a coating liquid (emulsion coating liquid). The viscosity of the obtained coating liquid was 65 mPas.

[Example 1]
Using a slot die (lip thickness (width) 3 mm) as shown in FIG. 2, the coating liquid obtained in Production Example 1 is applied (coated, dried) on the first transparent conductive film. A coating layer (light control layer) having a thickness of 20 μm was formed. Then, a second transparent conductive film was laminated on the coating layer (light control layer) to obtain a light control layer film.
The first transparent conductive film and the second transparent conductive film are configured by arranging a transparent conductive layer made of an ITO layer on a PET substrate, and have a thickness of 188 μm (transparent conductive film). Surface resistance value: 100Ω / □) was used.
The application conditions of the coating liquid were a line speed of 6 m / min , a gap L between the lip tip of the slot die and the transparent conductive film: 150 μm, and a vacuum pressure from the upstream: 0.4 kPa. By coating under the above conditions, a coating layer having a wet thickness of 40 μm was formed. The drying conditions of the coating layer were 40 ° C. and 5 minutes.

[Example 2]
A photochromic film was obtained in the same manner as in Example 1 except that the gap L was 250 μm under the coating conditions of the coating liquid. The wet thickness of the coating layer was 45 μm, and the thickness of the dimming layer was 22 μm.

[Example 3]
A photochromic film was obtained in the same manner as in Example 1 except that a slot die having a lip thickness of 1 mm was used and the gap L was set to 150 μm. The wet thickness of the coating layer was 49 μm, and the thickness of the dimming layer was 25 μm.

[Example 4]
A photochromic film was obtained in the same manner as in Example 3 except that the gap L was 250 μm under the coating conditions of the coating liquid. The wet thickness of the coating layer was 50 μm, and the thickness of the dimming layer was 25 μm.

[Example 5]
A light control film was obtained in the same manner as in Example 3 except that the gap L was set to 350 μm under the coating conditions of the coating liquid. The wet thickness of the coating layer was 44 μm, and the thickness of the dimming layer was 22 μm.

[Example 6]
A light control film was obtained in the same manner as in Example 3 except that the gap L was 400 μm under the coating conditions of the coating liquid. The wet thickness of the coating layer was 39 μm, and the thickness of the dimming layer was 19 μm.

[Comparative Example 1]
A photochromic film was obtained in the same manner as in Example 1 except that the gap L was set to 50 μm under the coating conditions of the coating liquid. The wet thickness of the coating layer was 43 μm, and the thickness of the dimming layer was 21 μm.

[Comparative Example 2]
A dimming film was obtained in the same manner as in Example 3 except that the gap L was set to 50 μm under the coating conditions of the coating liquid. The wet thickness of the coating layer was 45 μm, and the thickness of the dimming layer was 22 μm.

[Reference Example 1]
A dimming film was obtained in the same manner as in Example 1 except that the line speed was 0.5 m / min and the gap L was 50 μm under the coating conditions of the coating liquid. The wet thickness of the coating layer was 40 μm, and the thickness of the dimming layer was 20 μm.

<Evaluation>
The photochromic films obtained in Examples, Comparative Examples and Reference Examples were subjected to the following evaluations. The results are shown in Table 1.

(1) Haze value The haze value of the obtained light control film (normal mode, when no voltage was applied) was measured according to JIS7136.

(2) Appearance 1 (light scattering abnormality)
In a dark room, a fluorescent lamp was used as a light source, light was transmitted through a dimming film, and the transmitted light was visually observed. The part where the circular shading was partially observed due to the uneven film thickness was regarded as a light scattering abnormality, and the number was measured.

(3) Appearance 1 (painting streaks)
In a dark room, a fluorescent lamp was used as a light source, light was transmitted through a dimming film, and the transmitted light was visually observed. The portion where the shading was continuously observed in the MD direction was defined as a coating streak, and the number was measured.

As is clear from Table 1, according to the present invention, by setting the gap L to 100 μm or more, it is possible to form a light control layer by the emulsion coating liquid with a good appearance even if the line speed is high. The effect of improving the appearance becomes even more remarkable by reducing the lip thickness of the slot die and setting the gap L to 350 μm or less.

10 Transparent base material 20 Transparent conductive layer 100 Dimming film 110 First transparent conductive film 120 Dimming layer 130 Second transparent conductive film

Claims (4)

A method for producing a light control film, which comprises a coating step of applying a coating liquid containing an emulsified liquid crystal compound and an emulsified resin to a transparent conductive film using a slot die.
The line speed in the coating process is 2 m / min to 50 m / min .
The gap between the lip tip of the slot die and the transparent conductive film is 100 μm to 550 μm.
The lip width of the slot die is 5 mm or less.
The viscosity of the coating liquid is 20 mPas to 400 mPas at the time of discharging from the slot die.
The dimming film can be switched between a transmission mode and a scattering mode.
The haze value of the light control film in the scattering mode is 80% or more.
A method for manufacturing a light control film. The method for manufacturing a light control film according to claim 1, wherein the lip width of the slot die is 2 mm or less. The method for producing a dimming film according to claim 1 or 2, wherein the transparent conductive film has a thickness of 10 μm to 200 μm. The method for producing a light control film according to any one of claims 1 to 3, wherein the total amount of the liquid crystal compound and the resin is 30 parts by weight to 70 parts by weight with respect to 100 parts by weight of the coating liquid. ..

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