Polymer-dispersed liquid crystal film and method for manufacturing the same

Abstract

To provide a PDLC film capable of switching a transparent state and a scattering state in only a predetermined region.SOLUTION: A polymer dispersion type liquid crystal film includes a first transparent conductive film, a polymer dispersion type liquid crystal layer including polymer matrix and liquid crystal droplets dispersed in the polymer matrix, and a second transparent conductive film in this order, wherein the polymer dispersion type liquid crystal layer has a first region and a second region having different haze change amounts by applying a voltage in plan view, the haze change amount by applying the voltage in the first region is smaller than the change amount in the second region, and the liquid crystal droplets in the first region include a non-polymerizable liquid crystal compound and a liquid crystal polymer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polymer dispersed liquid crystal film and a method for manufacturing the polymer dispersed liquid crystal film. [Background technology]

[0002] BACKGROUND ART In recent years, light-control films that exhibit different appearances depending on the state of applied voltage have been applied to a variety of applications, such as displays such as advertisements and guide boards, and smart windows.

[0003] A PDLC film, which has a polymer dispersed liquid crystal (hereinafter sometimes referred to as "PDLC") layer between a pair of transparent electrode layers, is a type of light control film that can switch between a light scattering state (scattering state) and a light transmitting state (non-scattering state or transparent state) by switching between an applied voltage state and an unapplied voltage state. Specifically, the PDLC layer contains a polymer matrix and droplets of a liquid crystal compound (liquid crystal droplets) dispersed in the polymer matrix, and the liquid crystal droplets act as scattering particles, causing light scattering due to factors such as the difference in refractive index between the liquid crystal compound in the liquid crystal droplets and the polymer matrix.

[0004] The above-mentioned PDLC film generally has a cloudy appearance in the scattering state, and can therefore have two appearances: cloudy (scattering state) and transparent (non-scattering state). However, in consideration of design, there is a demand for a light-control film that can have other appearances.

[0005] In relation to the above demand, Patent Document 1 proposes a light-control film that can adjust the total amount of incident light, and that uses a dichroic substance instead of a liquid crystal compound, so that it has a transparent appearance in a non-scattering state and a colored appearance in a scattering state. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-189123 Summary of the Invention [Problem to be solved by the invention]

[0007] In conventional light control films, switching between the transparent state and the scattering state is performed over the entire surface of the film, and it is not possible to perform this switching only in a predetermined region.

[0008] The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide a polymer dispersed liquid crystal film that can be switched between a transparent state and a scattering state only in a specified area. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a polymer dispersed liquid crystal film comprising, in this order: a first transparent conductive film; a polymer dispersed liquid crystal layer comprising a polymer matrix and liquid crystal droplets dispersed in the polymer matrix; and a second transparent conductive film, wherein the polymer dispersed liquid crystal layer has, in a planar view, a first region and a second region in which the amount of change in haze due to application of a voltage is different, the amount of change in haze due to application of a voltage in the first region is smaller than the amount of change in the second region, and the liquid crystal droplets in the first region comprise a non-polymerizable liquid crystal compound and a liquid crystal polymer. In one embodiment, the liquid crystal droplets in the second region contain a non-polymerizable liquid crystal compound and a polymerizable liquid crystal compound. In one embodiment, the content weight ratio of the non-polymerizable liquid crystal compound to the polymerizable liquid crystal compound in the second region (non-polymerizable liquid crystal compound:polymerizable liquid crystal compound) is 99:1 to 70:30. In one embodiment, the liquid crystal polymer contained in the liquid crystal droplets in the first region is a polymerization product of the polymerizable liquid crystal compound contained in the liquid crystal droplets in the second region. In one embodiment, the difference between the haze of the first region and the haze of the second region increases with application of a voltage. In one embodiment, the liquid crystal polymer contained in the liquid crystal droplets in the first region is in a non-oriented state. In one embodiment, the difference between the haze of the first region and the haze of the second region is reduced by application of a voltage. In one embodiment, the liquid crystal polymer contained in the liquid crystal droplets in the first region is oriented in a predetermined direction. According to another aspect of the present invention, there is provided a method for producing a polymer dispersed liquid crystal film, the method comprising: applying a coating liquid containing a polymer matrix-forming resin, a non-polymerizable liquid crystal compound, a polymerizable liquid crystal compound, and a solvent to a first transparent conductive film to obtain a coating layer; drying the coating layer to obtain a polymer dispersed liquid crystal layer containing a polymer matrix and liquid crystal droplets containing the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound dispersed in the polymer matrix; laminating a second transparent conductive film on the polymer dispersed liquid crystal layer; and irradiating the polymer dispersed liquid crystal layer with active energy rays in a predetermined pattern while applying a voltage between the first transparent conductive film and the second transparent conductive film to form first regions containing liquid crystal droplets containing a liquid crystal polymer that is a polymerization product of the polymerizable liquid crystal compound and the non-polymerizable liquid crystal compound. According to another aspect of the present invention, there is provided a method for producing a polymer dispersed liquid crystal film, the method comprising: applying a coating liquid containing a polymer matrix-forming resin, a non-polymerizable liquid crystal compound, a polymerizable liquid crystal compound, and a solvent to a first transparent conductive film to obtain a coating layer; drying the coating layer to obtain a polymer dispersed liquid crystal layer containing a polymer matrix and liquid crystal droplets containing the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound dispersed in the polymer matrix; laminating a second transparent conductive film on the polymer dispersed liquid crystal layer; and irradiating the polymer dispersed liquid crystal layer with active energy rays in a predetermined pattern without applying a voltage between the first transparent conductive film and the second transparent conductive film to form first regions containing liquid crystal droplets containing a liquid crystal polymer that is a polymerization product of the polymerizable liquid crystal compound and the non-polymerizable liquid crystal compound. In one embodiment, the coating liquid is an emulsion coating liquid in which liquid crystal particles containing the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound are dispersed in the solvent. In one embodiment, the weight ratio of the total content of the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound to the content of the polymer matrix-forming resin in the coating liquid (liquid crystal compound:polymer matrix-forming resin) is 30:70 to 70:30. In one embodiment, the weight ratio of the non-polymerizable liquid crystal compound to the polymerizable liquid crystal compound in the coating liquid (non-polymerizable liquid crystal compound:polymerizable liquid crystal compound) is 99:1 to 70:30. [Effects of the Invention]

[0010] According to an embodiment of the present invention, the orientation of the liquid crystal compound is restricted within the liquid crystal droplets containing the liquid crystal polymer, thereby suppressing changes in haze due to changes in the applied voltage. Therefore, by changing the applied voltage while the liquid crystal polymer is present within the liquid crystal droplets in a desired region, it is possible to suppress changes in haze in that region while changing the haze in other regions. As a result, a light-control film can be provided that exhibits an appearance with a predetermined pattern either with or without applied voltage, and exhibits a highly uniform appearance in the other state. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1(a) is a schematic plan view of a PDLC film according to a first embodiment of the present invention; FIG. 1(b) is a schematic cross-sectional view illustrating the state of the PDLC film shown in FIG. 1(a) when no voltage is applied; and FIG. 1(c) is a schematic cross-sectional view illustrating the state of the PDLC film shown in FIG. 1(a) when a voltage is applied. [Figure 2] (a) is a schematic plan view of a PDLC film of a second embodiment of the present invention, (b) is a schematic cross-sectional view illustrating the state of the PDLC film shown in (a) when no voltage is applied, and (c) is a schematic cross-sectional view illustrating the state of the PDLC film shown in (a) when a voltage is applied. [Figure 3] 1 is a schematic diagram illustrating an example of a method for producing a PDLC film of the present invention. [Figure 4] 1 is a schematic diagram illustrating an example of a method for producing a PDLC film of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. In this specification, the term "to" indicating a range of values ​​includes the upper and lower limits.

[0013] A. Polymer dispersed liquid crystal film A polymer dispersed liquid crystal (PDLC) film according to an embodiment of the present invention comprises, in this order, a first transparent conductive film, a PDLC layer containing a polymer matrix and liquid crystal droplets dispersed in the polymer matrix, and a second transparent conductive film, wherein the PDLC layer has, in a planar view, a first region and a second region which have different amounts of haze change due to the application of a voltage, the amount of haze change due to the application of a voltage in the first region being smaller than the amount of change in the second region, and the liquid crystal droplets in the first region comprise a non-polymerizable liquid crystal compound and a liquid crystal polymer.

[0014] A-1. PDLC film of the first embodiment FIG. 1(a) is a schematic plan view of a PDLC film according to a first embodiment of the present invention; (b) is a schematic cross-sectional view illustrating the state of the PDLC film shown in (a) when no voltage is applied; and (c) is a schematic cross-sectional view illustrating the state of the PDLC film shown in (a) when a voltage is applied. The PDLC film 100a includes, in this order, a first transparent conductive film 10, a PDLC layer 20 containing a polymer matrix 22 and liquid crystal droplets 24 dispersed in the polymer matrix 22, and a second transparent conductive film 30. In plan view, the PDLC layer 20 has a first region A and a second region B, each of which exhibits a different amount of haze change upon application of voltage. The liquid crystal droplets 24 in the first region A contain a non-polymerizable liquid crystal compound 24a and a liquid crystal polymer 24c, with the liquid crystal polymer 24c typically existing in a non-oriented state. The liquid crystal droplets 24 in the second region B contain a non-polymerizable liquid crystal compound 24a and a polymerizable liquid crystal compound 24b. In this specification, the phrase "a compound is in a non-oriented state" means that the compound is not aligned with any regularity.

[0015] 1(b), in the PDLC film 100a when no voltage is applied, the non-polymerizable liquid crystal compound 24a and the liquid crystal polymer 24c in the liquid crystal droplets 24 in the first region A are both non-oriented, and the non-polymerizable liquid crystal compound 24a and the polymerizable liquid crystal compound 24b in the liquid crystal droplets 24 in the second region B are both non-oriented, resulting in scattering of transmitted light in both regions. Therefore, both the first region A and the second region B can be in a scattering state, and as a result, the entire main surface of the PDLC film 100a can be in a scattering state.

[0016] On the other hand, as shown in Figure 1(c), in the PDLC film 100a, when a voltage is applied, both the non-polymerizable liquid crystal compound 24a and the polymerizable liquid crystal compound 24b in the liquid crystal droplets 24 in the second region B are aligned perpendicular to the main surface of the transparent conductive film 10, 30, suppressing scattering of transmitted light and reducing the haze in that region. On the other hand, in the first region A, the presence of the non-oriented liquid crystal polymer 24c prevents the orientation of the non-polymerizable liquid crystal compound 24a, maintaining the non-oriented state, thereby still scattering transmitted light. Therefore, the change in haze due to the application of a voltage in the first region is smaller than that in the second region, and the difference between the haze in the first region and the second region increases with the application of a voltage.

[0017] As described above, when no voltage is applied, the entire main surface of the PDLC film 100a is in a scattering state, giving it a cloudy appearance, whereas when a voltage is applied, the haze in only the second region is significantly reduced, giving it a cloudy appearance in the first region and a transparent appearance in the second region. Thus, the PDLC film 100a can take on different appearances by switching between applying and not applying a voltage.

[0018] The voltage applied to the PDLC film during voltage application is a voltage that can operate the PDLC film (operating voltage), and can be, for example, 5 V to 200 V, and preferably 10 V to 100 V. In this specification, "haze during voltage application" refers to the haze when an operating voltage is applied to the PDLC film, and can be, for example, the haze when a voltage of 5 V or more, 10 V or more, or 20 V or more is applied.

[0019] The haze of the region of the PDLC film corresponding to the first region when no voltage is applied (hereinafter, sometimes simply referred to as "the haze of the first region") is, for example, 50% to 100%, preferably 70% to 100%. The haze of the first region when a voltage is applied is, for example, 40% to 100%, preferably 60% to 100%. The change in haze of the first region due to the application of a voltage (|haze when no voltage is applied - haze when voltage is applied|) is, for example, 0% to 40%, preferably 0% to 30%.

[0020] The haze of the region of the PDLC film corresponding to the second region when no voltage is applied (hereinafter, sometimes simply referred to as "the haze of the second region") is, for example, 50% to 100%, preferably 70% to 100%. The haze of the second region when a voltage is applied is, for example, 1% to 20%, preferably 1% to 10%. The change in haze of the second region due to the application of a voltage (|haze when no voltage is applied - haze when voltage is applied|) is, for example, 30% to 99%, preferably 60% to 99%.

[0021] The amount of change in haze in the first region due to application of a voltage is smaller than the amount of change in haze in the second region due to application of a voltage, and the difference is, for example, 10% to 99%, preferably 30% to 99%.

[0022] The total light transmittance of the region of the PDLC film corresponding to the first region when no voltage is applied (hereinafter, sometimes simply referred to as "total light transmittance of the first region") is, for example, 50% to 95%, preferably 60% to 90%. The total light transmittance of the first region when a voltage is applied is, for example, 50% to 95%, preferably 60% to 90%. The total light transmittance can be measured according to JIS K 7361.

[0023] The total light transmittance of the region of the PDLC film corresponding to the second region when no voltage is applied (hereinafter sometimes simply referred to as "total light transmittance of the second region") is, for example, 50% to 95%, preferably 60% to 90%. The total light transmittance of the second region when a voltage is applied is, for example, 70% to 95%, preferably 80% to 90%.

[0024] The thickness of the PDLC film is, for example, 30 μm to 250 μm, and preferably 50 μm to 150 μm.

[0025] A-1-1. First transparent conductive film The first transparent conductive film 10 typically includes a first transparent substrate 12 and a first transparent electrode layer 14 provided on one side thereof. The first transparent conductive film 10 may optionally include a hard coat layer on one or both sides of the first transparent substrate 12, and may also include a refractive index adjusting layer between the first transparent substrate 12 and the first transparent electrode layer 14.

[0026] The surface resistance value of the first transparent conductive film is preferably 1 Ω / □ to 1000 Ω / □, more preferably 5 Ω / □ to 300 Ω / □, and even more preferably 10 Ω / □ to 200 Ω / □.

[0027] The haze value of the first transparent conductive film is preferably 20% or less, more preferably 10% or less, and even more preferably 0.1% to 10%.

[0028] The total light transmittance of the first transparent conductive film is preferably 30% or more, more preferably 60% or more, and even more preferably 80% or more.

[0029] The first transparent substrate can be formed using any appropriate material. Specifically, for example, a polymer substrate such as a film or a plastic substrate is preferably used. This is because it has excellent smoothness and wettability with the transparent electrode layer-forming composition, and can significantly improve productivity through continuous production using a roll.

[0030] The material constituting the first transparent substrate is typically a polymer film mainly composed of a thermoplastic resin. Examples of thermoplastic resins include polyester resins; cycloolefin resins such as polynorbornene; acrylic resins; polycarbonate resins; and cellulose resins. Among these, polyester resins, cycloolefin resins, and acrylic resins are preferred. These resins are excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, and the like. The above-mentioned thermoplastic resins may be used alone or in combination of two or more. Optical films used in polarizing plates, such as low-retardation substrates, high-retardation substrates, retardation plates, absorptive polarizing films, and polarized selective reflection films, can also be used as the first transparent substrate.

[0031] The thickness of the first transparent substrate is preferably 200 μm or less, more preferably 3 μm to 100 μm, and even more preferably 5 μm to 70 μm. By setting the thickness of the first transparent substrate to 200 μm or less, the function of the PDLC layer can be fully exhibited.

[0032] The total light transmittance of the first transparent substrate is preferably 30% or more, more preferably 60% or more, and even more preferably 80% or more.

[0033] The first transparent electrode layer can be formed using a metal oxide such as indium tin oxide (ITO), zinc oxide (ZnO), or tin oxide (SnO). Preferably, a transparent electrode layer containing ITO is formed. A transparent electrode layer containing ITO has excellent transparency. The first transparent electrode layer can be patterned into a desired shape depending on the purpose.

[0034] The light transmittance of the first transparent electrode layer is preferably 85% or more, more preferably 87% or more, and even more preferably 90% or more. By using a transparent electrode layer having a light transmittance in this range, high light transmittance is achieved in the transparent state. The higher the light transmittance, the better, but the upper limit is, for example, 99%.

[0035] Preferably, the first transparent electrode layer contains crystal grains. The inclusion of crystal grains can improve light transmittance. There is no limitation on the method for forming crystal grains, but for example, heating in air can suitably form crystal grains. The area occupancy rate of the crystal grains in the transparent electrode layer is, for example, 30% or more, preferably 50% or more, and more preferably 80% or more. The upper limit of this area occupancy rate is, for example, 100%. If the area occupancy rate of the crystal grains is within the above range, the light transmittance can be improved. The area occupancy rate of the crystal grains can be calculated from the area ratio between the crystal grain region and the amorphous region by observing the surface of the transparent electrode layer with a transmission electron microscope (TEM).

[0036] The surface roughness Ra of the first transparent electrode layer is, for example, 0.1 nm or more. If the surface roughness Ra of the first transparent electrode layer is less than 0.1 nm, adhesion to the substrate may be impaired. The upper limit of the surface roughness Ra of the first transparent electrode layer is preferably less than 1.2 nm, more preferably 1.0 nm or less, even more preferably less than 1.0 nm, and particularly preferably 0.8 nm or less. If the surface roughness Ra of the first transparent electrode layer is too large, it may be difficult to form crystal grains appropriately. In this specification, the surface roughness Ra refers to the arithmetic mean roughness Ra measured by an AFM (Atomic Force Microscope).

[0037] The thickness of the first transparent electrode layer is, for example, 10 nm or more, preferably 15 nm or more. If the thickness of the transparent electrode layer is less than 10 nm, the area occupancy rate of the crystal grains may decrease. The upper limit of the thickness of the first transparent electrode layer is, for example, 50 nm or less, preferably 35 nm or less, more preferably less than 30 nm, and even more preferably 27 nm or less. If the thickness of the transparent electrode layer exceeds 50 nm, the transmittance may decrease and the surface roughness of the transparent electrode layer may increase.

[0038] The first transparent electrode layer is provided on one surface of the first transparent substrate by, for example, sputtering. After forming the metal oxide layer by sputtering, it can be crystallized by annealing. Annealing is performed by heat treatment at, for example, 120°C to 300°C for 10 to 120 minutes.

[0039] The refractive index adjusting layer can control the hue and / or transmittance of the PDLC film. The refractive index adjusting layer may consist of a single layer or a laminate of two or more layers.

[0040] The refractive index of the refractive index-adjusting layer is preferably 1.3 to 1.8, more preferably 1.35 to 1.7, and even more preferably 1.38 to 1.68. In the case of a single layer, for example, when the transparent electrode layer is made of ITO, a low refractive index is desirable so that the refractive index of ITO can be optically reduced, and for example, a refractive index of 1.38 to 1.46 is preferable. This allows for optimal reduction of interfacial reflection between the transparent substrate and the transparent electrode layer.

[0041] The refractive index adjusting layer is made of an inorganic material, an organic material, or a mixture of an inorganic material and an organic material. Materials for forming the refractive index adjusting layer include NaF, Na3AlF6, LiF, MgF2, and CaF 2、 SiO2, LaF3, CeF3, Al2O3, TiO2, Ta2O5, ZrO2, ZnO, ZnS, SiO x(x is 1.5 or more and less than 2), and organic substances such as acrylic resin, epoxy resin, urethane resin, melamine resin, alkyd resin, and siloxane polymer. In particular, it is preferable to use a thermosetting resin made of a mixture of melamine resin, alkyd resin, and organic silane condensate as the organic substance.

[0042] The refractive index adjusting layer may contain nanoparticles with an average particle size of 1 nm to 100 nm. By including nanoparticles in the refractive index adjusting layer, the refractive index of the refractive index adjusting layer itself can be easily adjusted.

[0043] The content of the nanoparticles in the refractive index-matching layer is preferably 0.1% to 90% by weight, more preferably 10% to 80% by weight, and even more preferably 20% to 70% by weight.

[0044] Examples of inorganic oxides that form nanoparticles include silicon oxide (silica), hollow nanosilica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, zirconium oxide, and niobium oxide. Among these, silicon oxide (silica), titanium oxide, aluminum oxide, zinc oxide, tin oxide, zirconium oxide, and niobium oxide are preferred. These may be used alone or in combination of two or more.

[0045] The thickness of the refractive index-matching layer is preferably 10 nm to 200 nm, more preferably 20 nm to 150 nm, and even more preferably 30 nm to 130 nm. If the thickness of the refractive index-matching layer is too small, it is difficult to form a continuous film. On the other hand, if the thickness of the refractive index-matching layer is too large, the transparency in the transparent state tends to decrease and cracks tend to occur easily.

[0046] The refractive index adjusting layer can be formed using the above-mentioned materials by a wet method, a coating method such as gravure coating or bar coating, a vacuum deposition method, a sputtering method, an ion plating method, or the like.

[0047] A-1-2.PDLC layer The PDLC layer 20 includes a polymer matrix 22 and droplets (liquid crystal droplets) 24 of a liquid crystal compound dispersed in the polymer matrix 22. As shown in Fig. 1, the PDLC layer 20 has a first region A and a second region B. The liquid crystal droplets 24 in the first region A include a non-polymerizable liquid crystal compound 24a and a non-oriented liquid crystal polymer 24c, while the liquid crystal droplets 24 in the second region B include a non-polymerizable liquid crystal compound 24a and a polymerizable liquid crystal compound 24b. The first region A and the second region B can be formed in any suitable pattern depending on the design desired for the PDLC film.

[0048] The polymer matrix may be composed of any appropriate resin. The resin for forming the polymer matrix may be appropriately selected depending on the light transmittance, the refractive index of the liquid crystal compound, the adhesion to the transparent conductive film, etc. For example, water-soluble or water-dispersible resins such as urethane-based resins, polyvinyl alcohol-based resins, polyethylene-based resins, polypropylene-based resins, and acrylic-based resins may be preferably used. The resin for forming the polymer matrix may be used alone or in combination.

[0049] The content of the polymer matrix in the PDLC layer in both the first and second regions is, for example, 30 to 70% by weight, preferably 35 to 65% by weight, and more preferably 40 to 60% by weight. If the content of the polymer matrix is ​​within this range, good light control function can be achieved at a moderate operating voltage, good mechanical strength can be obtained, and liquid crystal leakage from the edges can be prevented.

[0050] Any suitable non-polymerizable liquid crystal compound can be used, preferably a liquid crystal compound having a birefringence Δn (=ne-no; ne is the refractive index of the liquid crystal compound molecules in the long axis direction, and no is the refractive index of the liquid crystal compound molecules in the short axis direction) of 0.05 to 0.50 at a wavelength of 589 nm, more preferably a liquid crystal compound having a birefringence Δn of 0.10 to 0.45.

[0051] The dielectric anisotropy of the non-polymerizable liquid crystal compound may be positive or negative. The non-polymerizable liquid crystal compound may be, for example, a nematic, smectic, or cholesteric liquid crystal compound. It is preferable to use a nematic liquid crystal compound because it can achieve excellent transparency in the transparent state.

[0052] Examples of nematic liquid crystal compounds include biphenyl-based compounds, phenylbenzoate-based compounds, cyclohexylbenzene-based compounds, azoxybenzene-based compounds, azobenzene-based compounds, azomethine-based compounds, terphenyl-based compounds, biphenylbenzoate-based compounds, cyclohexylbiphenyl-based compounds, phenylpyridine-based compounds, cyclohexylpyrimidine-based compounds, cholesterol-based compounds, fluorine-based compounds, etc. These low-molecular-weight liquid crystal compounds may be used alone or in combination.

[0053] The polymerizable liquid crystal compound can be appropriately selected depending on the light transmittance, compatibility with the non-polymerizable liquid crystal compound, etc. The polymerizable liquid crystal compound may be a bifunctional or higher crosslinked type. Examples of the polymerizable liquid crystal compound include polymerizable mesogenic compounds described in JP-A-2002-533742 (WO 00 / 37585), EP 358208 (US 5,211,877), EP 66137 (US 4,388,453), WO 93 / 22397, EP 0261712, DE 19504224, DE 4408171, and GB 2280445. Specific examples of such polymerizable mesogenic compounds include BASF's product name LC242. Nematic liquid crystal monomers are preferred as the polymerizable liquid crystal compound.

[0054] Liquid crystal polymers are typically polymerization products of the above-mentioned polymerizable liquid crystal compounds. Polymerization of the polymerizable liquid crystal compounds forms polymers, and crosslinking can form network structures, but these are non-liquid crystals. Therefore, in liquid crystal polymers, for example, the transition to a liquid crystal phase, glass phase, or crystalline phase due to temperature changes that is specific to liquid crystal compounds does not occur.

[0055] The liquid crystal polymer is typically present in a non-oriented state in the liquid crystal droplets. Because the liquid crystal polymer in the liquid crystal droplets is in a non-oriented state, the first region can maintain a high haze (for example, 40% to 100%, preferably 60% to 100%) even when a voltage is applied.

[0056] The total content of the non-polymerizable liquid crystal compound and the liquid crystal polymer in the first region is, for example, 30% to 70% by weight, preferably 35% to 65% by weight, and more preferably 40% to 60% by weight. The weight ratio of the non-polymerizable liquid crystal compound to the liquid crystal polymer in the first region (non-polymerizable liquid crystal compound:liquid crystal polymer) is, for example, 99:1 to 70:30, and preferably 95:5 to 80:20. The total content of the polymer matrix, non-polymerizable liquid crystal compound, and the liquid crystal polymer in the first region can be, for example, 90% to 99.9% by weight, and preferably 95% to 99.9% by weight.

[0057] The total content of the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound in the second region is, for example, 30% to 70% by weight, preferably 35% to 65% by weight, and more preferably 40% to 60% by weight. The weight ratio of the non-polymerizable liquid crystal compound to the polymerizable liquid crystal compound (non-polymerizable liquid crystal compound:polymerizable liquid crystal compound) in the second region is, for example, 99:1 to 70:30, and preferably 95:5 to 80:20. The total content of the polymer matrix, non-polymerizable liquid crystal compound, and polymerizable liquid crystal compound in the second region can be, for example, 90% to 99.9% by weight, and preferably 95% to 99.9% by weight.

[0058] As described in detail in Section B, a PDLC layer having a first region and a second region can be formed by polymerizing a polymerizable liquid crystal compound in a predetermined region of a PDLC layer containing liquid crystal droplets containing a non-polymerizable liquid crystal compound and a polymerizable liquid crystal compound to form a liquid crystal polymer. In this case, the predetermined region becomes the first region, and the other region becomes the second region. Therefore, in the first and second regions, the liquid crystal droplets may further contain a polymerization initiator. The content of the polymerization initiator is as described in Section B. Furthermore, unreacted polymerizable liquid crystal compound may remain in the liquid crystal droplets in the first region. The content of unreacted polymerizable liquid crystal compound in the first region is, for example, 3% by weight or less, preferably 1% by weight or less. Furthermore, it is preferable that the liquid crystal droplets in the second region are substantially free of liquid crystal polymer. The content of the liquid crystal polymer in the second region is, for example, 3% by weight or less, preferably 1% by weight or less.

[0059] The average particle diameter of the liquid crystal droplets can be, for example, 0.3 μm to 9 μm, preferably 0.4 μm to 8 μm. If the average particle diameter of the liquid crystal droplets is too small, the liquid crystal droplet size is smaller than the wavelength of light, so light passes through the liquid crystal droplets without scattering, which can result in a problem of insufficient haze being obtained. If the average particle diameter is too large, the liquid crystal droplet size is too large compared to the wavelength of light, which can result in a problem of insufficient haze being obtained. Note that the average particle diameter of the liquid crystal droplets in the PDLC layer is the volume-average particle diameter of the liquid crystal droplets when viewed from a direction perpendicular to the main surface of the PDLC film.

[0060] The thickness of the PDLC layer is typically 2 μm to 40 μm, preferably 3 μm to 35 μm, and more preferably 4 μm to 30 μm.

[0061] A-1-3. Second transparent conductive film The second transparent conductive film 30 typically includes a second transparent substrate 32 and a second transparent electrode layer 34 provided on one side thereof. The second transparent conductive film 30 may optionally include a hard coat layer on one or both sides of the second transparent substrate 32, and may also include a refractive index adjusting layer between the second transparent substrate 32 and the second transparent electrode layer 34.

[0062] The surface resistance value of the second transparent conductive film is preferably 1 Ω / □ to 1000 Ω / □, more preferably 5 Ω / □ to 300 Ω / □, and even more preferably 10 Ω / □ to 200 Ω / □.

[0063] The haze value of the second transparent conductive film is preferably 20% or less, more preferably 10% or less, and even more preferably 0.1% to 10%.

[0064] The total light transmittance of the second transparent conductive film is preferably 30% or more, more preferably 60% or more, and even more preferably 80% or more.

[0065] The second transparent substrate and the second transparent electrode layer can be described in the same manner as the first transparent substrate and the first transparent electrode layer, respectively. The second transparent conductive film may have the same structure as the first transparent conductive film, or may have a different structure.

[0066] A-2. PDLC film of the second embodiment FIG. 2(a) is a schematic plan view of a PDLC film according to a second embodiment of the present invention; (b) is a schematic cross-sectional view illustrating the state of the PDLC film shown in (a) when no voltage is applied; and (c) is a schematic cross-sectional view illustrating the state of the PDLC film shown in (a) when a voltage is applied. The PDLC film 100b includes, in this order, a first transparent conductive film 10, a PDLC layer 20 containing a polymer matrix 22 and liquid crystal droplets 24 dispersed in the polymer matrix 22, and a second transparent conductive film 30. In plan view, the PDLC layer 20 has a first region A and a second region B, each of which exhibits a different amount of change in haze upon application of a voltage. The liquid crystal droplets 24 in the first region A contain a non-polymerizable liquid crystal compound 24a and a liquid crystal polymer 24c, and typically, the liquid crystal polymer 24c is aligned in a predetermined direction (in the illustrated example, perpendicular to the main surfaces of the transparent conductive films 10 and 30). The liquid crystal droplets 24 in the second region B contain a non-polymerizable liquid crystal compound 24a and a polymerizable liquid crystal compound 24b.

[0067] As shown in FIG. 2(b), in the PDLC film 100b when no voltage is applied, the non-polymerizable liquid crystal compound 24a and the polymerizable liquid crystal compound 24b in the liquid crystal droplets 24 in the second region B are both in a non-oriented state, resulting in scattering of transmitted light. On the other hand, in the first region A, the non-polymerizable liquid crystal compound 24a is oriented along the orientation direction of the liquid crystal polymer 24c, resulting in suppressed scattering of transmitted light. Therefore, in the PDLC film 100b, the first region A can be in a transparent state, and the second region B can be in a scattering state.

[0068] On the other hand, as shown in FIG. 2(c), in the PDLC film 100b, when a voltage is applied, both the non-polymerizable liquid crystal compound 24a and the polymerizable liquid crystal compound 24b in the liquid crystal droplets 24 in the second region B are aligned perpendicular to the major surfaces of the transparent conductive films 10 and 30, suppressing scattering of transmitted light and resulting in reduced haze. Meanwhile, in the first region A, the alignment of the non-polymerizable liquid crystal compound 24a does not change significantly, so scattering of transmitted light is still suppressed. Therefore, the change in haze due to voltage application in the first region is smaller than that in the second region, and the difference between the haze in the first region and the haze in the second region decreases due to voltage application.

[0069] As described above, when no voltage is applied, the PDLC film 100b has a transparent appearance in the first region and a cloudy appearance in the second region. When a voltage is applied, the haze in the second region is significantly reduced, and both regions become transparent, resulting in the entire main surface appearing transparent. Therefore, the PDLC film 100b can exhibit different appearances by switching between applying and not applying a voltage.

[0070] The voltage applied to the PDLC film during voltage application is a voltage that can operate the PDLC film (operating voltage), and can be, for example, 5V to 200V, and preferably 10V to 100V.

[0071] The haze of the first region when no voltage is applied is, for example, 1% to 20%, preferably 1% to 10%. The haze of the first region when a voltage is applied is, for example, 1% to 20%, preferably 1% to 10%. The change in haze of the first region due to voltage application (|haze when no voltage is applied−haze when voltage is applied|) is, for example, 0% to 20%, preferably 0% to 10%.

[0072] The haze of the second region when no voltage is applied is, for example, 50% to 100%, preferably 70% to 100%. The haze of the second region when a voltage is applied is, for example, 1% to 20%, preferably 1% to 10%. The change in haze of the second region due to voltage application (|haze when no voltage is applied−haze when voltage is applied|) is, for example, 30% to 99%, preferably 60% to 99%.

[0073] The amount of change in haze in the first region due to application of a voltage is smaller than the amount of change in haze in the second region due to application of a voltage, and the difference is, for example, 10% to 99%, preferably 30% to 99%.

[0074] The total light transmittance of the first region when no voltage is applied is, for example, 70% to 95%, preferably 80% to 90%.The total light transmittance of the first region when a voltage is applied is, for example, 70% to 95%, preferably 80% to 90%.

[0075] The total light transmittance of the second region when no voltage is applied is, for example, 50% to 95%, preferably 60% to 90%.The total light transmittance of the second region when a voltage is applied is, for example, 70% to 95%, preferably 80% to 90%.

[0076] The thickness of the PDLC film is, for example, 30 μm to 250 μm, and preferably 50 μm to 150 μm.

[0077] Regarding the PDLC film of the second embodiment, the same explanations as for the first transparent conductive film and the second transparent conductive film in the PDLC film of the first embodiment can be applied to the first transparent conductive film and the second transparent conductive film, respectively. Furthermore, the same explanations as for the PDLC layer in the PDLC film of the first embodiment can be applied to the PDLC layer, except that the liquid crystal polymer contained in the liquid crystal droplets in the first region is oriented in a predetermined direction.

[0078] In the first region of the PDLC layer, the liquid crystal polymer contained in the liquid crystal droplets is oriented in a predetermined direction. The liquid crystal polymer is preferably oriented in a direction substantially perpendicular to the main surfaces of the first transparent conductive film and the second transparent conductive film, at an angle of, for example, 90°±5°, preferably 90°±3°. Because the liquid crystal polymer in the liquid crystal droplets is oriented in a predetermined direction, the first region can maintain a low haze (for example, 1% to 20%, preferably 1% to 10%) even when no voltage is applied.

[0079] B. Manufacturing method of polymer dispersed liquid crystal film According to one aspect of the present invention, there is provided a method for manufacturing a polymer dispersed liquid crystal (PDLC) film. The method for manufacturing a PDLC film according to an embodiment of the present invention includes the steps of: (Step A) applying a coating liquid containing a polymer matrix-forming resin, a non-polymerizable liquid crystal compound, a polymerizable liquid crystal compound, and a solvent to a first transparent conductive film to obtain a coating layer; (Step B) drying the coating layer to obtain a PDLC layer containing a polymer matrix and liquid crystal droplets containing the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound dispersed in the polymer matrix; (Step C) laminating a second transparent conductive film on the PDLC layer; and (Step D) irradiating the PDLC layer with active energy rays in a predetermined pattern to form first regions containing liquid crystal droplets containing a liquid crystal polymer that is a polymerization product of the polymerizable liquid crystal compound and the non-polymerizable liquid crystal compound; According to the method for producing a PDLC film according to an embodiment of the present invention, it is possible to form a PDLC layer having a first region in which the liquid crystal droplets contain a non-polymerizable liquid crystal compound and a liquid crystal polymer, and a second region in which the liquid crystal droplets contain a non-polymerizable liquid crystal compound and a polymerizable liquid crystal compound, and as a result, it is possible to suitably obtain the PDLC film described in Section A.

[0080] In one embodiment, the active energy ray irradiation in step D is performed in a state where no voltage is applied between the first transparent conductive film and the second transparent conductive film. In another embodiment, the active energy ray irradiation in step D is performed in a state where a voltage is applied between the first transparent conductive film and the second transparent conductive film.

[0081] B-1. Process A In step A, a coating liquid containing a polymer matrix-forming resin, a non-polymerizable liquid crystal compound, a polymerizable liquid crystal compound, and a solvent is applied to a first transparent conductive film to obtain a coating layer.

[0082] The coating liquid is preferably an emulsion in which liquid crystal particles containing a non-polymerizable liquid crystal compound and a polymerizable liquid crystal compound are dispersed in a solvent (hereinafter, this may be referred to as an "emulsion coating liquid"). In one embodiment, the coating liquid is an emulsion coating liquid in which polymer matrix-forming resin particles and liquid crystal particles containing a non-polymerizable liquid crystal compound and a polymerizable liquid crystal compound are dispersed in a solvent. The emulsion coating liquid preferably further contains a polymerization initiator in the liquid crystal particles, and may further contain any appropriate additives depending on the purpose.

[0083] The solvent is preferably water or a mixture of water and a water-miscible organic solvent. Examples of the water-miscible organic solvent include C1-3 alcohol, acetone, and DMSO. The non-polymerizable liquid crystal compound, polymerizable liquid crystal compound, and polymer matrix-forming resin are as described in Section A-1-2. Optional additives include dispersants, leveling agents, and crosslinking agents.

[0084] The content of the liquid crystal compound in the solid content of the coating liquid (total content of the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound) can be, for example, 30% by weight to 70% by weight, preferably 35% by weight to 65% by weight, and more preferably 40% by weight to 60% by weight.

[0085] The weight ratio of the non-polymerizable liquid crystal compound to the polymerizable liquid crystal compound in the coating liquid (non-polymerizable liquid crystal compound:polymerizable liquid crystal compound) may be preferably 99:1 to 70:30, more preferably 95:5 to 80:20.

[0086] The content of the polymer matrix-forming resin in the solid content of the coating liquid can be, for example, 30 to 70% by weight, preferably 35 to 65% by weight, and more preferably 40 to 60% by weight.

[0087] The weight ratio of the content of the liquid crystal compound (total content of the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound) to the content of the polymer matrix-forming resin in the coating liquid (liquid crystal compound:polymer matrix-forming resin) can be, for example, 30:70 to 70:30, preferably 35:65 to 65:35, and more preferably 40:60 to 60:40. The total content of the polymer matrix-forming resin, non-polymerizable liquid crystal compound, and polymerizable liquid crystal compound in the solid content of the coating liquid can be, for example, 90% by weight to 99.9% by weight, and preferably 95% by weight to 99.9% by weight.

[0088] The average particle size of the liquid crystal particles is preferably 0.3 μm or more, more preferably 0.4 μm or more. The average particle size of the liquid crystal particles is preferably 9 μm or less, more preferably 8 μm or less. If the average particle size of the liquid crystal particles is within this range, the average particle size of the liquid crystal droplets in the PDLC layer can be set within the desired range. The average particle size of the liquid crystal particles is the volume average particle size.

[0089] The average particle size of the liquid crystal particles preferably has a relatively narrow particle size distribution. The coefficient of variation (CV value) of the average particle size of the liquid crystal particles may be, for example, less than 0.40, preferably 0.35 or less, and more preferably 0.30 or less. In one embodiment, an emulsion coating liquid may be used that is substantially free of liquid crystal particles having a particle size of less than 0.3 μm or more than 9 μm (for example, an emulsion coating liquid in which the volume ratio of liquid crystal particles having a particle size of less than 0.3 μm or more than 9 μm to the total volume of liquid crystal particles is 10% or less).

[0090] The average particle diameter of the resin particles for forming a polymer matrix is ​​preferably 10 nm to 500 nm, more preferably 30 nm to 300 nm, and even more preferably 50 nm to 200 nm. Two or more types of resin particles differing in type and / or average particle diameter may be used. The average particle diameter of the resin particles for forming a polymer matrix means the volume-average median diameter and can be measured using a dynamic light scattering particle size distribution analyzer.

[0091] As the polymerization initiator, any appropriate photopolymerization initiator can be used depending on the purpose, desired properties, and the like. Specific examples of photopolymerization initiators include 2,2-dimethoxy-2-phenylacetophenone, acetophenone, benzophenone, xanthone, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, benzoin propyl ether, benzil dimethyl ketal, N,N,N',N'-tetramethyl-4,4'-diaminobenzophenone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-dipentoxyphenylphosphine oxide, bis(2,6-dimethoxy-benzoyl)-(2,4,4-trimethyl-pentyl)-phosphine oxide, and thioxanthone compounds. The photopolymerization initiators may be used alone or in combination of two or more. The content of the photopolymerization initiator is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, relative to 100 parts by weight of the polymerizable liquid crystal compound.

[0092] Examples of dispersants include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. The content of the dispersant is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 1 part by weight, per 100 parts by weight of the emulsion coating liquid.

[0093] Examples of the leveling agent include acrylic leveling agents, fluorine-based leveling agents, silicone-based leveling agents, etc. The content of the leveling agent is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 1 part by weight, per 100 parts by weight of the emulsion coating liquid.

[0094] Examples of the crosslinking agent include an aziridine-based crosslinking agent, an isocyanate-based crosslinking agent, etc. The content of the crosslinking agent is preferably 0.5 to 10 parts by weight, more preferably 0.8 to 5 parts by weight, per 100 parts by weight of the emulsion coating liquid.

[0095] The emulsion coating liquid can be prepared, for example, by mixing a resin emulsion or resin particle dispersion containing polymer matrix-forming resin particles, a liquid crystal emulsion containing liquid crystal particles containing a liquid crystal compound and a polymerization initiator, and optional additives (e.g., dispersants, leveling agents, crosslinking agents). If necessary, a solvent may be added during mixing. Alternatively, the emulsion coating liquid can be prepared by adding a non-polymerizable liquid crystal compound, a polymerizable liquid crystal compound, a water-dispersible resin, a polymerization initiator, and optional additives to a solvent and mechanically dispersing the mixture.

[0096] The resin emulsion and liquid crystal emulsion can be prepared by, for example, a mechanical emulsification method, a microchannel method, a membrane emulsification method, or the like. Among these, the liquid crystal emulsion is preferably prepared by the membrane emulsification method. The membrane emulsification method can suitably produce an emulsion with a uniform particle size distribution. For details of the membrane emulsification method, reference can be made to the disclosures of JP-A-4-355719 and JP-A-2015-40994 (which are incorporated herein by reference).

[0097] The solid content concentration of the emulsion coating liquid can be, for example, 20% to 60% by weight, and preferably 30% to 50% by weight.

[0098] The viscosity of the emulsion coating liquid can be appropriately adjusted so that it can be applied to the first transparent conductive film in a suitable manner. The viscosity of the emulsion coating liquid during application is preferably 20 mPas to 400 mPas, more preferably 30 mPas to 300 mPas, and even more preferably 40 mPas to 200 mPas. If the viscosity is less than 20 mPas, convection of the solvent becomes significant when the solvent is dried, which may result in an unstable thickness of the PDLC layer. If the viscosity exceeds 400 mPas, the bead of the emulsion coating liquid may become unstable. The viscosity of the emulsion coating liquid can be measured, for example, using a rheometer MCR302 manufactured by Anton Paar. The viscosity used here is the shear viscosity value at 20°C and a shear rate of 1000 (1 / s).

[0099] The emulsion coating liquid is typically applied to the surface of the first transparent conductive film on the transparent electrode layer side. The first transparent conductive film is as described in Section A-1-1.

[0100] Any appropriate method can be used as the coating method. For example, roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, knife coating (comma coating, etc.), etc. can be mentioned. Among them, roll coating is preferred. For example, the description of JP-A-2019-5698 can be referred to for coating by roll coating using a slot die.

[0101] The thickness of the coating layer is preferably 3 μm to 40 μm, more preferably 4 μm to 30 μm, and even more preferably 5 μm to 20 μm.Within these ranges, a PDLC layer with excellent thickness uniformity can be obtained.

[0102] B-2.Process B In step B, the coating layer is dried to obtain a PDLC layer containing a polymer matrix and liquid crystal droplets containing a non-polymerizable liquid crystal compound and a polymerizable liquid crystal compound dispersed in the polymer matrix. The solvent is removed from the coating layer by drying, and the resin particles for forming the polymer matrix are fused together to form a PDLC layer having a structure in which liquid crystal droplets are dispersed in a polymer matrix.

[0103] The coating layer can be dried by any appropriate method. Specific examples of the drying method include heat drying, hot air drying, etc. When the emulsion coating liquid contains a crosslinking agent, a crosslinked structure of the polymer matrix can be formed during drying.

[0104] The drying temperature is preferably 20° C. to 150° C., more preferably 25° C. to 80° C. The drying time is preferably 1 minute to 100 minutes, more preferably 2 minutes to 10 minutes.

[0105] B-3.Process C In step C, a second transparent conductive film is laminated on the PDLC layer, thereby obtaining a PDLC film having the first transparent conductive film, the PDLC layer, and the second transparent conductive film in this order.

[0106] The second conductive film is as described in Section A-1-3, and is laminated onto the PDLC layer so that the second transparent electrode layer faces the PDLC layer. To ensure sufficient adhesion, the lamination is preferably performed using a laminator while applying a lamination pressure of 0.006 MPa / m to 7 MPa / m, more preferably 0.06 MPa / m to 0.7 MPa / m.

[0107] B-4.Process D In step D, the PDLC layer is irradiated with active energy rays in a predetermined pattern to form first regions containing liquid crystal droplets containing a liquid crystal polymer, which is a polymerization product of a polymerizable liquid crystal compound, and a non-polymerizable liquid crystal compound. Specifically, in the regions irradiated with active energy rays (irradiated regions), the polymerizable liquid crystal compound in the liquid crystal droplets polymerizes to form a liquid crystal polymer, resulting in the formation of liquid crystal droplets containing a non-polymerizable liquid crystal compound and a liquid crystal polymer. On the other hand, in the regions not irradiated with active energy rays (unirradiated regions), the polymerizable liquid crystal compound remains unreacted, resulting in the liquid crystal droplets containing a non-polymerizable liquid crystal compound and a polymerizable liquid crystal compound. Thus, the irradiated regions of the PDLC layer become first regions A containing liquid crystal droplets containing a non-polymerizable liquid crystal compound and a liquid crystal polymer, and the unirradiated regions become second regions B containing liquid crystal droplets containing a non-polymerizable liquid crystal compound and a polymerizable liquid crystal compound. The liquid crystal polymer contained in the liquid crystal droplets in the first regions A is a polymerization product of the polymerizable liquid crystal compound contained in the liquid crystal droplets in the second regions B. The content ratio of the non-polymerizable liquid crystal compound to the polymerizable liquid crystal compound in the droplets in the unirradiated region can roughly correspond to the content ratio at the time when the liquid crystal droplets are first formed, i.e., the content ratio of the non-polymerizable liquid crystal compound to the polymerizable liquid crystal compound in the coating liquid.

[0108] The active energy rays are irradiated through a photomask with a predetermined pattern. Examples of the active energy rays include ultraviolet rays, infrared rays, X-rays, α rays, β rays, γ rays, and electron beams. Among these, ultraviolet rays are preferred. Furthermore, the active energy rays are preferably collimated rays that have a high degree of linearity from the irradiation source.

[0109] The ultraviolet irradiation conditions can be appropriately set depending on the type of polymerizable liquid crystal compound, the transmittance of the transparent conductive film, the absorption wavelength of the photopolymerization initiator, etc. The irradiation intensity is, for example, 0.1 mW / cm 2 ~1000mW / cm 2 , preferably 1 mW / cm 2 ~100mW / cm 2 The irradiation dose can be, for example, 10 mJ / cm 2 ~10,000mJ / cm 2 , preferably 100 mJ / cm 2~5000mJ / cm 2 The irradiation temperature can be, for example, from -20°C to 80°C, and preferably from -20°C to 60°C.

[0110] 3 and 4 are schematic diagrams illustrating an example of active energy ray irradiation in a method for producing a PDLC film according to an embodiment of the present invention. In the embodiment shown in FIG. 3, active energy ray irradiation is performed through a photomask 40 without applying a voltage between the first transparent conductive film 10 and the second transparent conductive film 30. According to this embodiment, in the liquid crystal droplets 24 in the irradiated region of the PDLC layer 20, the polymerizable liquid crystal compound 24b is polymerized in a non-oriented state, and the resulting liquid crystal polymer 24c is also non-oriented. Therefore, this embodiment can suitably produce the PDLC film of the first embodiment described in Section A-1.

[0111] In the embodiment shown in FIG. 4, active energy ray irradiation is performed with a voltage applied between the first transparent conductive film 10 and the second transparent conductive film 30 via a photomask 40. According to this embodiment, in the liquid crystal droplets 24 in the irradiated region of the PDLC layer 20, the polymerizable liquid crystal compound 24b is polymerized while oriented in a predetermined direction along the electric field (in the illustrated example, the direction perpendicular to the main surfaces of the transparent conductive films 10 and 30), thereby forming a liquid crystal polymer 24c with this orientation fixed. Therefore, this embodiment can suitably obtain the PDLC film of the second embodiment described in Section A-2. The voltage applied during active energy ray irradiation is not limited as long as the desired orientation (in other words, the desired haze in the first region) is achieved, and can be, for example, 10 V to 200 V, preferably 20 V to 100 V.

[0112] In one embodiment, by irradiating the PDLC film with active energy rays using a photomask having a plurality of light-transmitting portions with different aperture ratios, the first regions can be formed in the regions corresponding to the light-transmitting portions at a ratio corresponding to the aperture ratios of the light-transmitting portions, and thus the regions corresponding to the light-transmitting portions in the resulting PDLC film can exhibit a haze corresponding to the aperture ratios when viewed as a whole.

[0113] For example, by using a photomask whose aperture ratio increases continuously from the right end to the left end and irradiating with active energy rays without applying a voltage, a PDLC film can be obtained in which the entire surface is in a scattering state when no voltage is applied and the haze increases continuously from the right end to the left end when a voltage is applied.Furthermore, by using a photomask whose aperture ratio increases continuously from the right end to the left end and irradiating with active energy rays while applying a voltage, a PDLC film can be obtained in which the entire surface is transparent when a voltage is applied and the haze decreases continuously from the right end to the left end when no voltage is applied. [Example]

[0114] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The methods for measuring each property are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are by weight.

[0115] (1) Thickness Measurement was carried out using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). (2) Volume average particle size of liquid crystal particles in liquid crystal emulsion 0.1 wt% of the liquid crystal emulsion was added to 200 ml of an aqueous electrolyte solution (Coulter's "Isoton II"), and the resulting mixture was used as a measurement sample. Using a Multisizer 3 (Coulter's, aperture size = 20 μm), the sample was divided into 256 equal logarithmic intervals from 0.4 μm to 12 μm, and the volume of each particle size was measured to calculate the volume-average particle size. When particles of 12 μm or larger were present, the aperture size was changed to 30 μm, and the sample was divided into 256 equal logarithmic intervals from 0.6 μm to 18 μm, and the volume-average particle size was calculated by measuring the volume of each particle size. (3) Average particle size of resin particles A measurement sample was prepared by adding a few drops of the resin dispersion to 100 mL of water. Using a dynamic light scattering particle size distribution analyzer (Microtrac, device name "Nanotrac150"), the measurement sample was placed in the measurement holder of the device, and measurements were performed after checking on the device monitor that the concentration was measurable. (4) Hayes Measurements were carried out in accordance with JIS K 7136 using a Nippon Denshoku product called "NDH4000."

[0116] [Example 1] (First and second transparent conductive films) An ITO layer was formed by sputtering on one surface of a PET substrate (thickness: 50 μm) to obtain a transparent conductive film having a structure of [transparent substrate / transparent electrode layer].

[0117] (Preparation of emulsion coating liquid) A liquid crystal emulsion was prepared by mixing 53.7 parts of a non-polymerizable liquid crystal compound (JNC Corporation, product name "LX-153XX," birefringence Δn = 0.149 (ne = 1.651, no = 1.502), viscosity = 48.5 mPa·s), 5.9 parts of a polymerizable liquid crystal compound (BASF, product name "PALIOCOLOR LC-242"), 0.1 parts of a photoinitiator (IGM, product name "OMNIRAD651"), 39.8 parts of purified water, and 0.5 parts of a dispersant (Dai-ichi Kogyo Seiyaku Co., Ltd., "Noigen ET159") in a homogenizer at 100 rpm for 10 minutes. The average particle size of the resulting liquid crystal particles was 3.4 μm. An emulsion coating solution (solid concentration: 40 wt%) was obtained by mixing 38.4 parts of the above liquid crystal emulsion, 19.1 parts of a polyether-based polyurethane resin aqueous dispersion (manufactured by DSM, product name "NeoRez R967", polymer average particle size: 80 nm, CV value = 0.27, solid content: 40 wt%), 17.0 parts of a polyester-based polyurethane resin aqueous dispersion (manufactured by Sanyo Chemical Industries, product name "Eucoat C-102", polymer average particle size: 168 nm, CV value = 0.23, solid content: 45 wt%), 0.1 parts of a leveling agent (manufactured by DIC, product name "F-444"), and 1.1 parts of a crosslinking agent (tris[3-(2-methylaziridin-1-yl)propionic acid] = propylidinetrimethyl), and 24.3 parts of pure water.

[0118] (Application and drying of emulsion coating liquid) The emulsion coating liquid was applied to the ITO layer of the first transparent conductive film to form a 20 μm-thick coating layer. The coating was performed using a slot die at a line speed of 6 m / min. The coating layer was then dried at 25°C for 8 minutes to form an 8 μm-thick PDLC layer.

[0119] (Lamination of second transparent conductive film) A second transparent conductive film was laminated on the PDLC layer with the ITO layer facing the PDLC layer using a laminator under a lamination pressure of 0.4 MPa / m, thereby obtaining a PDLC film.

[0120] (active energy ray irradiation) On both sides of the PDLC film, a portion of the transparent conductive film was half-cut down to the transparent substrate to expose the transparent electrode layer, and the exposed portion was used as an extraction electrode. A photomask with a predetermined pattern was placed on the electrode-treated PDLC film, and the film was exposed to 10 mW / cm of light under a UV-LED lamp (manufactured by Hamamatsu Photonics, product name "C11924-101", peak wavelength 365 nm) while applying a voltage of 50 V. 2 The film was exposed to light for 10 minutes.

[0121] [Example 2] A PDLC film was obtained in the same manner as in Example 1, except that the ultraviolet irradiation was carried out without applying a voltage (applied voltage: 0 V).

[0122] The optical properties of the PDLC films obtained in the examples were evaluated by the following methods. The results are shown in Table 1. ≪Optical properties≫ Using an AC power supply "EC750SA" manufactured by NF Corporation, the haze was measured when an AC voltage of 0V to 50V was applied to the PDLC film.

[0123] [Table 1]

[0124] As shown in Table 1, for all of the PDLC films obtained in the examples, the amount of change in haze due to voltage application in the first region (irradiated region) was smaller than the amount of change in the second region (unirradiated region). Furthermore, the PDLC film of Example 1 exhibited a predetermined pattern consisting of transparent first regions and opaque second regions when no voltage was applied, and exhibited a highly uniform, transparent appearance across the entire main surface when a voltage of 50 V was applied. On the other hand, the PDLC film of Example 2 exhibited a highly uniform, opaque appearance across the entire main surface when no voltage was applied, and exhibited a predetermined pattern consisting of opaque first regions and transparent second regions when a voltage of 50 V was applied. [Industrial Applicability]

[0125] The PDLC film of the present invention is suitable for use in various applications such as displays such as advertisements and guide boards, and smart windows. [Explanation of symbols]

[0126] 100 PDLC film 10 First transparent conductive film 20 PDLC layers 22 Polymer matrix 24 Liquid Crystal Droplets 24a Non-polymerizable liquid crystal compound 24b Polymerizable liquid crystal compound 24c Liquid Crystal Polymer 30 Second transparent conductive film

Claims

1. A polymer dispersed liquid crystal film comprising, in this order: a first transparent conductive film; a polymer dispersed liquid crystal layer including a polymer matrix and liquid crystal droplets dispersed in the polymer matrix; and a second transparent conductive film, the polymer dispersed liquid crystal layer has, in a plan view, a first region and a second region which have different amounts of change in haze due to application of a voltage; a change in haze due to application of a voltage in the first region is smaller than the change in haze in the second region; The polymer dispersed liquid crystal film, wherein the liquid crystal droplets in the first region include a non-polymerizable liquid crystal compound and a liquid crystal polymer.

2. 2. The polymer dispersed liquid crystal film of claim 1, wherein the liquid crystal droplets in the second region include a non-polymerizable liquid crystal compound and a polymerizable liquid crystal compound.

3. 3. The polymer dispersed liquid crystal film according to claim 2, wherein a content weight ratio of the non-polymerizable liquid crystal compound to the polymerizable liquid crystal compound in the second region (non-polymerizable liquid crystal compound:polymerizable liquid crystal compound) is 99:1 to 70:

30.

4. 4. The polymer dispersed liquid crystal film according to claim 2, wherein the liquid crystal polymer contained in the liquid crystal droplets in the first region is a polymerization product of the polymerizable liquid crystal compound contained in the liquid crystal droplets in the second region.

5. 5. The polymer dispersed liquid crystal film according to claim 1, wherein a difference between the haze of the first region and the haze of the second region increases by application of a voltage.

6. The polymer dispersed liquid crystal film according to claim 5 , wherein the liquid crystal polymer contained in the liquid crystal droplets in the first region is in a non-oriented state.

7. 5. The polymer dispersed liquid crystal film according to claim 1, wherein a difference between the haze of the first region and the haze of the second region is reduced by application of a voltage.

8. The polymer dispersed liquid crystal film according to claim 7 , wherein the liquid crystal polymer contained in the liquid crystal droplets in the first region is oriented in a predetermined direction.

9. applying a coating liquid containing a polymer matrix-forming resin, a non-polymerizable liquid crystal compound, a polymerizable liquid crystal compound, and a solvent to a first transparent conductive film to obtain a coating layer; drying the coating layer to obtain a polymer dispersed liquid crystal layer containing a polymer matrix and liquid crystal droplets containing the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound dispersed in the polymer matrix; laminating a second transparent conductive film on the polymer dispersed liquid crystal layer; and irradiating the polymer dispersed liquid crystal layer with active energy rays through a photomask having a predetermined pattern while applying a voltage between the first transparent conductive film and the second transparent conductive film, thereby forming an irradiated region into a first region containing liquid crystal droplets containing a liquid crystal polymer that is a polymerization product of the polymerizable liquid crystal compound and the non-polymerizable liquid crystal compound, and forming a non-irradiated region into a second region containing liquid crystal droplets containing the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound; A method for producing a polymer dispersed liquid crystal film, comprising:

10. applying a coating liquid containing a polymer matrix-forming resin, a non-polymerizable liquid crystal compound, a polymerizable liquid crystal compound, and a solvent to a first transparent conductive film to obtain a coating layer; drying the coating layer to obtain a polymer dispersed liquid crystal layer containing a polymer matrix and liquid crystal droplets containing the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound dispersed in the polymer matrix; laminating a second transparent conductive film on the polymer dispersed liquid crystal layer; and irradiating the polymer dispersed liquid crystal layer with active energy rays through a photomask having a predetermined pattern in a state where no voltage is applied between the first transparent conductive film and the second transparent conductive film, thereby forming an irradiated region into a first region containing liquid crystal droplets containing a liquid crystal polymer that is a polymerization product of the polymerizable liquid crystal compound and the non-polymerizable liquid crystal compound, and forming a non-irradiated region into a second region containing liquid crystal droplets containing the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound; A method for producing a polymer dispersed liquid crystal film, comprising:

11. 11. The method for producing a polymer dispersed liquid crystal film according to claim 9, wherein the coating liquid is an emulsion coating liquid in which liquid crystal particles containing the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound are dispersed in the solvent.

12. 12. The method for producing a polymer dispersed liquid crystal film according to claim 9, wherein a weight ratio of a total content of the non-polymerizable liquid crystal compound and the polymerizable liquid crystal compound to a content of the polymer matrix forming resin in the coating liquid (liquid crystal compound:polymer matrix forming resin) is 30:70 to 70:

30.

13. 13. The method for producing a polymer dispersed liquid crystal film according to claim 9, wherein the content weight ratio of the non-polymerizable liquid crystal compound to the polymerizable liquid crystal compound in the coating liquid (non-polymerizable liquid crystal compound:polymerizable liquid crystal compound) is 99:1 to 70:30.

Images