Polymer dispersed liquid crystal film

Abstract

A polymer-dispersed liquid crystal film according to an embodiment of the present invention comprises, 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, the polymer-dispersed liquid crystal layer having a first region and a second region, the first region is a region in which the liquid crystal droplet contains a non-polymerizable liquid crystal component, a liquid crystal polymer, and a dichroic dye, and the second region is a region in which the liquid crystal droplet contains a non-polymerizable liquid crystal component, a polymerizable liquid crystal component, and a dichroic dye.

Description

Technical Field

[0001] This invention relates to polymer-dispersed liquid crystal films. Background Technology

[0002] In recent years, dimming films that exhibit different appearances depending on the applied voltage have been applied to various uses such as displays for advertising, directional 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 dimming film. By switching between a voltage-applied state and a voltage-free state, it is possible to switch between a light-scattering state (scattering state) and a light-transmitting state (non-scattering state or transparent state). Specifically, the PDLC layer comprises a polymer matrix and droplets of liquid crystal components dispersed in the polymer matrix (liquid crystal droplets). The liquid crystal droplets become scattering particles due to the refractive index difference between the liquid crystal components in the liquid crystal droplets and the polymer matrix, thus causing light scattering (e.g., Patent Document 1).

[0004] The aforementioned PDLC film generally exhibits a cloudy appearance under scattering conditions. Therefore, it can present two appearances: cloudy (scattering state) and transparent (non-scattering state). However, considering the design of the appearance, there is a desire for dimming films that can present other appearances.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2021-60521 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The present invention was made to solve the above-mentioned existing problems. Its main objective is to provide a polymer-dispersed liquid crystal film with high appearance design flexibility. Specifically, it is to provide a polymer-dispersed liquid crystal film that can switch between a transparent state and a colored state with a desired pattern.

[0010] Problem Solving Methods

[0011] [1] According to one aspect of the present invention, a polymer-dispersed liquid crystal film is provided, which sequentially comprises 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 a first region and a second region, the first region being a region in which the liquid crystal droplets comprise non-polymerizable liquid crystal components, liquid crystal polymers and dichroic pigments, and the second region being a region in which the liquid crystal droplets comprise non-polymerizable liquid crystal components, polymerizable liquid crystal components and dichroic pigments.

[0012] [2] In the polymer-dispersed liquid crystal film described in [1] above, the change in transmittance of the dichroic pigment in the first region at the absorption peak wavelength caused by the applied voltage can be less than the change in transmittance in the second region above.

[0013] [3] In the polymer-dispersed liquid crystal film described in [1] or [2] above, the average particle size of the liquid crystal droplets can be less than 1 μm.

[0014] [4] In any of the above [1] to [3] polymer-dispersed liquid crystal films, in the first region, the content of the liquid crystal polymer may be 1 part to 30 parts by weight relative to 100 parts by weight of the non-polymerizable liquid crystal component.

[0015] [5] In any of the polymer-dispersed liquid crystal films described in any of [1] to [4] above, in the first region above, the content ratio of the dichroic pigment may be 0.1 parts by weight to 10 parts by weight relative to 100 parts by weight of the nonpolymeric liquid crystal component.

[0016] [6] In any of the polymer-dispersed liquid crystal films described in any of [1] to [5] above, the difference between the haze of the first region and the haze of the second region may increase due to the application of voltage.

[0017] [7] In any of the polymer-dispersed liquid crystal films described in any of [1] to [5] above, the difference between the haze of the first region and the haze of the second region can be reduced by the application of voltage.

[0018] [8] In any of the above [1] to [7] polymer-dispersed liquid crystal films, a reflective layer may be further included on the side opposite to the side where the polymer-dispersed liquid crystal layer is disposed on the first transparent conductive film or the second transparent conductive film.

[0019] The effects of the invention

[0020] According to an embodiment of the present invention, within a liquid crystal droplet containing a liquid crystal polymer, the orientation of the liquid crystal components is restricted, and the liquid crystal droplet contains a dichroic pigment. Therefore, changes in haze and coloring state caused by changes in the applied voltage state can be suppressed. Thus, by changing the applied voltage state while ensuring the presence of a liquid crystal polymer within the liquid crystal droplet in a desired region, changes in haze and coloring state in that region can be suppressed while changes in haze and coloring state in other regions can be achieved. Attached Figure Description

[0021] Figure 1 (a) is a top view of an example of a PDLC film according to an embodiment of the present invention, (b) is a cross-sectional view illustrating the state of the PDLC film shown in (a) when no voltage is applied, and (c) is a cross-sectional view illustrating the state of the PDLC film shown in (a) when a voltage is applied.

[0022] Figure 2 (a) is a top view of another example of the PDLC film according to an embodiment of the present invention, (b) is a cross-sectional view illustrating the state of the PDLC film shown in (a) when no voltage is applied, and (c) is a cross-sectional view illustrating the state of the PDLC film shown in (a) when a voltage is applied.

[0023] Figure 3 (a) and (b) are cross-sectional schematic diagrams illustrating the states of the PDLC film according to an embodiment of the present invention when no voltage is applied and when a voltage is applied.

[0024] Figure 4 This is a schematic diagram illustrating an example of a method for manufacturing the PDLC film of the present invention.

[0025] Figure 5 This is a schematic diagram illustrating an example of a method for manufacturing the PDLC film of the present invention.

[0026] Symbol Explanation

[0027] 100 PDLC membrane

[0028] 10 First transparent conductive film

[0029] 20 PDLC layers

[0030] 22 Polymer Matrix

[0031] 24 LCD droplets

[0032] 24a Non-polymeric liquid crystal component

[0033] 24b Polymerizable liquid crystal component

[0034] 24c liquid crystal polymer

[0035] 24d dichroic pigment

[0036] 30 Second transparent conductive film Detailed Implementation

[0037] The preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. Furthermore, the embodiments can be appropriately combined. In this specification, the "~" indicating a numerical range includes both the upper and lower limits of the value. The accompanying drawings are used to clarify the description; compared to the embodiments, the width, thickness, shape, etc., of each part may sometimes be schematically shown, but these are merely examples and do not limit the interpretation of the present invention.

[0038] A. Polymer-dispersed liquid crystal film

[0039] Figure 1 (a) is a top view schematic diagram of an example of a polymer-dispersed liquid crystal (PDLC) film according to one embodiment (first embodiment) of the present invention; (b) is a cross-sectional schematic diagram illustrating the state of the PDLC film shown in (a) when no voltage is applied; and (c) is a cross-sectional schematic diagram illustrating the state of the PDLC film shown in (a) when a voltage is applied. The PDLC film 100a sequentially includes: a first transparent conductive film 10, a PDLC layer 20 comprising a polymer matrix 22 and liquid crystal droplets 24 dispersed in the polymer matrix 22, and a second transparent conductive film 30.

[0040] The PDLC layer 20 has a first region A and a second region B. The liquid crystal droplets 24 in the first region A contain a non-polymerizable liquid crystal component 24a, a liquid crystal polymer 24c, and a dichroic pigment 24d. The liquid crystal droplets 24 in the second region B contain a non-polymerizable liquid crystal component 24a, a polymerizable liquid crystal component 24b, and a dichroic pigment 24d.

[0041] like Figure 1As shown in (b), in the PDLC film 100a without applied voltage, the non-polymerizable liquid crystal component 24a, liquid crystal polymer 24c, and dichroic pigment 24d in the liquid crystal droplets 24 of region A are all in a non-oriented state. Furthermore, the non-polymerizable liquid crystal component 24a, polymerizable liquid crystal component 24b, and dichroic pigment 24d in the liquid crystal droplets 24 of region B are all in a non-oriented state. Therefore, in both region A and region B, scattering of transmitted light occurs due to the refractive index difference between the polymer matrix and the liquid crystal component and / or liquid crystal polymer, and absorption occurs due to the dichroic pigment. Thus, both region A and region B can be in a colored scattering state, resulting in the entire main surface of the PDLC film 100a being in a colored scattering state without applied voltage. It should be noted that, in this specification, "in a non-oriented state" means that the compound is not arranged in a certain ordered manner.

[0042] On the other hand, such as Figure 1 As shown in (c), in the PDLC film 100a under applied voltage, the non-polymerizable liquid crystal component 24a, polymerizable liquid crystal component 24b, and dichroic pigment 24d in the liquid crystal droplets 24 in region B are all oriented along a given direction (thickness direction in the example figure). Consequently, in region B, the scattering and absorption of transmitted light are suppressed, resulting in lower haze (transparency) and lighter color (colorlessness). On the other hand, in region A, due to the presence of the non-oriented liquid crystal polymer 24c, the orientation of the non-polymerizable liquid crystal component 24a and dichroic pigment 24d is restricted, thus maintaining a non-oriented state. Consequently, in region A, the scattering and absorption of transmitted light occur in the same manner as when no voltage is applied. As a result, in the PDLC film 100a under applied voltage, region A may be in a colored scattering state, and region B may be in a colorless and transparent state. Here, the colorless and transparent state means that the haze is lower than in the colored scattering state and the color is lighter, not that it is completely colorless and transparent.

[0043] In the PDLC film 100a, the change in haze in region A caused by the application of voltage is less than the aforementioned change in region B, and the difference in haze between region A and region B increases due to the application of voltage. Furthermore, the transmittance T of the dichroic pigment in region A at the absorption peak wavelength caused by the application of voltage... A The change is less than the transmittance T in region B of the second region. A The change in the transmittance T of region A in the first region. A Transmittance T of region B in the second region A The difference increases due to the application of voltage.

[0044] The haze of the PDLC film in the region corresponding to the first region (hereinafter sometimes simply referred to as "haze of the first region") when no voltage is applied is, for example, 50% to 100%, preferably 70% to 100%. The haze of the first region when voltage is applied is, for example, 40% to 100%, preferably 60% to 100%. The change in haze of the first region caused by the application of voltage (|haze when no voltage is applied - haze when voltage is applied|) is, for example, 0% to 40%, preferably 0% to 30%.

[0045] The haze of the PDLC film in the region corresponding to the second region (hereinafter sometimes simply referred to as "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 voltage is applied is, for example, 1% to 20%, preferably 1% to 10%. The change in haze of the second region caused by the application of voltage (|haze when no voltage is applied - haze when voltage is applied|) is, for example, 30% to 99%, preferably 60% to 99%.

[0046] The difference between the change in haze in the first region caused by the application of voltage and the change in haze in the second region caused by the application of voltage is, for example, 10% to 99%, preferably 30% to 99%.

[0047] The transmittance T of the PDLC film in the regions corresponding to the first region and the second region mentioned above when no voltage is applied. A The specific formulation can vary depending on the type and ratio of dichroic pigments, and can be appropriately adjusted according to the intended purpose.

[0048] The transmittance T of the PDLC film in the region corresponding to the first region mentioned above when no voltage is applied. A (Hereinafter, it is sometimes simply referred to as "the transmittance T of region 1") A For example, the transmittance is 40% to 90%, preferably 40% to 70%. The transmittance T of the first region when voltage is applied... A For example, it is 40% to 95%, preferably 40% to 70%. The transmittance T of the first region caused by the application of voltage. A The change in transmittance (T without applied voltage) A - Transmittance T when voltage is applied A For example, it can be 0%~10%, or 0%~5%.

[0049] The transmittance T of the PDLC film in the region corresponding to the second region mentioned above when no voltage is applied. A (Hereinafter, it is sometimes simply referred to as "the transmittance T of the second region") A For example, the transmittance T of the second region when voltage is applied is 40% to 90%, preferably 40% to 70%.A For example, 45% to 95%, preferably 60% to 95%. The transmittance T of the second region caused by the application of voltage. A The change in transmittance (T without applied voltage) A - Transmittance T when voltage is applied A For example, it is 5%~30%, and another example is 5%~20%.

[0050] The transmittance T of region 1 caused by the application of voltage A The change in the transmittance T of the second region caused by the application of voltage A The difference in the amount of change is, for example, 5% to 25%, or, for example, 5% to 20%.

[0051] The voltage applied to the PDLC film when applying voltage is a voltage that enables the PDLC film to operate (operating voltage), such as 5V to 200V, preferably 10V to 100V. In this specification, "when applying voltage" means that an operating voltage is applied to the PDLC film, such as a voltage of 30V.

[0052] The thickness of the PDLC film is, for example, 30 μm to 250 μm, preferably 50 μm to 150 μm.

[0053] A-1. First transparent conductive film

[0054] Typically, the first transparent conductive film 10 has a first transparent substrate 12 and a first transparent electrode layer 14 disposed on one side thereon. The first transparent conductive film 10 may have a hard coating on one or both sides of the first transparent substrate 12 as needed. In addition, a refractive index adjustment layer may be provided between the first transparent substrate 12 and the first transparent electrode layer 14.

[0055] The surface resistivity of the first transparent conductive film is preferably 1Ω / □ to 1000Ω / □, more preferably 5Ω / □ to 300Ω / □, and even more preferably 10Ω / □ to 200Ω / □.

[0056] The haze of the first transparent conductive film is preferably 20% or less, more preferably 10% or less, and even more preferably 0.1% to 10%.

[0057] 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.

[0058] The first transparent substrate can be formed from any suitable material. Specifically, polymeric substrates such as films and plastic substrates are preferred. This is because they offer excellent smoothness and wettability to the composition used to form the transparent electrode layer, and productivity can be significantly improved through continuous production using rollers.

[0059] Typically, the first transparent substrate is a polymer film primarily composed of thermoplastic resin. Examples of thermoplastic resins include: polyester resins; cyclic olefin resins such as polynorbornene; acrylic resins; polycarbonate resins; and cellulose resins. Polyester resins, cyclic olefin resins, or acrylic resins are preferred. These resins exhibit excellent transparency, mechanical strength, thermal stability, and moisture barrier properties. The aforementioned thermoplastic resins can be used alone or in combination of two or more.

[0060] 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 making the thickness of the first transparent substrate 200 μm or less, the function of the PDLC layer can be fully utilized.

[0061] 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.

[0062] The first transparent electrode layer can be formed, for example, using metal oxides such as indium tin oxide (ITO), zinc oxide (ZnO), or tin oxide (SnO2). In this case, the metal oxide can be an amorphous metal oxide or a crystalline metal oxide. Alternatively, the first transparent electrode layer can be formed from metal nanowires such as silver nanowires (AgNW), carbon nanotubes (CNTs), organic conductive films, metal layers, or laminates thereof. It is preferable to form a transparent electrode layer containing ITO. The transparent electrode layer containing ITO has excellent transparency. The first transparent electrode layer can be patterned into a desired shape according to the purpose.

[0063] The total 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 with such a range of total light transmittance, a PDLC film with high total light transmittance in a transparent state can be obtained. The higher the total light transmittance, the more preferred, and the upper limit is, for example, 99%.

[0064] The thickness of the first transparent electrode layer is, for example, 10 nm or more, preferably 15 nm or more. The thickness of the first transparent electrode layer is, for example, 50 nm or less, preferably 35 nm or less, and more preferably 30 nm or less.

[0065] The first transparent electrode layer can be formed on one side of the first transparent substrate, for example, by sputtering. After the metal oxide layer is formed by sputtering, crystallization can occur by annealing. Annealing can be performed, for example, by heat treatment at 120°C to 300°C for 10 to 120 minutes.

[0066] Regarding the refractive index adjustment layer and the hard coating, a structure known in the art can be adopted; therefore, a detailed description of their structure is omitted.

[0067] A-2. PDLC layer

[0068] The PDLC layer 20 comprises a polymer matrix 22 and droplets (liquid crystal droplets) 24 of liquid crystal components dispersed in the polymer matrix 22. For example... Figure 1 As shown, the PDLC layer 20 has a first region A and a second region B. The liquid crystal droplets 24 in the first region A contain a non-polymerizable liquid crystal component 24a, a liquid crystal polymer 24c, and a dichroic pigment 24d. The liquid crystal droplets 24 in the second region B contain a non-polymerizable liquid crystal component 24a, a polymerizable liquid crystal component 24b, and a dichroic pigment 24d. The first region A and the second region B can be formed by any suitable pattern according to the desired appearance design of the PDLC film.

[0069] The polymer matrix can be formed from any suitable resin. The resin used to form the polymer matrix can be appropriately selected based on factors such as light transmittance, the refractive index of the liquid crystal component, and the adhesion to the transparent conductive film. For example, water-soluble or water-dispersible resins such as urethane resins, polyvinyl alcohol resins, polyethylene resins, polypropylene resins, and acrylic resins are preferred. The polymer matrix forming resin can be used alone or in combination.

[0070] As a non-polymerizable liquid crystal component, any non-polymerizable liquid crystal compound can be used alone or in combination of two or more, depending on factors such as birefringence and compatibility with polymerizable liquid crystal components. It should be noted that, in the following description, the characteristics of the liquid crystal component (birefringence, dielectric constant, etc.) refer to the characteristics of the liquid crystal component as a whole, which may contain multiple liquid crystal compounds.

[0071] The birefringence of the nonpolymeric liquid crystal component at a wavelength of 589 nm (Δn = refractive index of the liquid crystal component along its long axis, no = refractive index of the liquid crystal component along its short axis) is preferably 0.05~0.50, more preferably 0.10~0.45.

[0072] In the example shown, a nonpolymerizable liquid crystal component with positive dielectric anisotropy is used, but the dielectric anisotropy of the nonpolymerizable liquid crystal component can be either positive or negative.

[0073] Non-polymerizable liquid crystal components can be, for example, nematic, smectic, or cholesteric liquid crystal components. Since excellent transparency can be achieved in the transparent state, nematic liquid crystal components are preferred.

[0074] Examples of nematic liquid crystal compounds include: biphenyl compounds, phenyl benzoate compounds, cyclohexylbenzene compounds, azobenzene compounds, azomethyl base compounds, terphenyl compounds, biphenyl benzoate compounds, cyclohexylbiphenyl compounds, phenylpyridine compounds, cyclohexylpyrimidine compounds, cholesterol compounds, and fluorine compounds. These low-molecular-weight liquid crystal compounds can be used alone or in combination.

[0075] As a polymerizable liquid crystal component, any polymerizable liquid crystal compound can be used alone or in combination of two or more, depending on factors such as birefringence and compatibility with non-polymerizable liquid crystal components. The polymerizable liquid crystal compound can be a cross-linked type with two or more functions. Examples of polymerizable liquid crystal compounds include those described in Japanese Patent Application Publication No. 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445. A specific example of such a polymerizable mesocrystalline compound is BASF's trade name LC242. Nematic liquid crystal monomers are preferred as polymerizable liquid crystal compounds.

[0076] The birefringence of the polymeric liquid crystal component at a wavelength of 589 nm (Δn = refractive index of the liquid crystal component along its long axis, no = refractive index of the liquid crystal component along its short axis) is preferably 0.05~0.50, more preferably 0.10~0.45.

[0077] Typically, liquid crystal polymers are polymerization products of the aforementioned polymerizable liquid crystal components. Polymers can be formed through the polymerization of polymerizable liquid crystal components, and network structures can be formed through cross-linking, but these are non-liquid crystals. Therefore, in liquid crystal polymers, the temperature-induced transformation to liquid crystal phase, glassy phase, or crystalline phase characteristic of liquid crystal compounds does not occur.

[0078] Typically, the liquid crystal polymer exists in a non-oriented state within the liquid crystal droplet. By making the liquid crystal polymer in the liquid crystal droplet non-oriented, the first region can maintain a high haze (e.g., 40% to 100%, preferably 60% to 100%) even when a voltage is applied.

[0079] As dichroic pigments, any suitable dichroic pigment that is compatible with both non-polymeric and polymeric liquid crystal components (sometimes collectively referred to as "liquid crystal components") can be used. It can be a dichroic pigment with a positive or negative Δε. The dichroic pigment itself can exhibit liquid crystal properties. Only one dichroic pigment can be used, or two or more can be used in combination.

[0080] Specific examples of dichroic dyes include azo dyes, anthraquinone dyes, naphthoquinone dyes, dinaphthylbenzene dyes, quinoline ketone dyes, tetraazine dyes, and benzothiadiazole dyes. Among these, considering factors such as absorbance coefficient, solubility in liquid crystal components, and lightfastness, dichroic dyes containing anthraquinone or azo dyes are preferred. For example, azo dyes, anthraquinone dyes, or mixtures thereof described in the "Liquid Crystal Devices Handbook" edited by the 142nd Committee of the Japanese Society for the Promotion of Science (JSP), published by the Japan Industrial News Agency (1989), pp. 192-196 and 724-730, can be used. Furthermore, various commercially available dichroic dyes are also available, and these can be used appropriately.

[0081] The proportion of polymer matrix in the PDLC layer is, for example, 30% to 70% by weight in both the first and second regions, preferably 35% to 65% by weight, and more preferably 40% to 60% by weight. When the proportion of polymer matrix is ​​within the above range, it is possible to obtain good dimming function with a suitable operating voltage, good mechanical strength, and prevention of liquid crystal leakage from the ends.

[0082] The ratio of the content of the polymer matrix to the total content of the non-polymeric liquid crystal component, liquid crystal polymer and dichroic pigment in the first region (the former: the latter (by weight)) is 30:70 to 70:30, preferably 35:65 to 65:35, and more preferably 40:60 to 60:40.

[0083] The proportion of the liquid crystal polymer in the first region relative to 100 parts by weight of the non-polymerizable liquid crystal component can be, for example, 1 to 30 parts by weight, preferably 5 to 20 parts by weight.

[0084] The proportion of the dichroic pigment in the first region relative to 100 parts by weight of the non-polymerizable liquid crystal component can be, for example, 0.1 to 10 parts by weight, preferably 0.5 to 7 parts by weight.

[0085] The total content of the polymer matrix, non-polymerizable liquid crystal component, liquid crystal polymer and dichroic pigment in the first region is typically 80% to 100% by weight, for example, 90% to 99.9% by weight, preferably 95% to 99.9% by weight.

[0086] The ratio of the content of the polymer matrix to the total content of the non-polymeric liquid crystal component, the polymeric liquid crystal component and the dichroic pigment in the second region (the former: the latter (by weight)) is 30:70 to 70:30, preferably 35:65 to 65:35, and more preferably 40:60 to 60:40.

[0087] The proportion of the polymeric liquid crystal component in the second region relative to 100 parts by weight of the non-polymeric liquid crystal component can be, for example, 1 to 30 parts by weight, preferably 5 to 20 parts by weight.

[0088] The proportion of the dichroic pigment in the second region relative to 100 parts by weight of the nonpolymeric liquid crystal component can be, for example, 0.1 to 10 parts by weight, preferably 0.5 to 7 parts by weight.

[0089] The total content of the polymer matrix, non-polymeric liquid crystal component, polymeric liquid crystal component and dichroic pigment in the second region is typically 80% to 100% by weight, for example, 90% to 99.9% by weight, preferably 95% to 99.9% by weight.

[0090] Unreacted polymeric liquid crystal components may remain in the liquid crystal droplets in the first region. The proportion of unreacted polymeric liquid crystal components in the first region is, for example, 3% by weight or less, preferably 1% by weight or less. Furthermore, it is preferable that liquid crystal polymers are substantially absent from the liquid crystal droplets in the second region. The proportion of liquid crystal polymers in the second region is, for example, 3% by weight or less, preferably 1% by weight or less.

[0091] As needed, the PDLC layer may further contain any suitable additives. As detailed in section B, a PDLC layer having regions 1 and 2 can be formed by polymerizing the polymeric liquid crystal component to form a liquid crystal polymer in a given region of a PDLC layer containing liquid crystal droplets containing non-polymerizable liquid crystal components, polymerizable liquid crystal components, and dichroic pigments. In this case, the given region becomes region 1, and the other regions become region 2. Thus, the PDLC layer (more specifically, the liquid crystal droplets) may further contain a polymerization initiator. Other additives include dispersants, leveling agents, crosslinking agents, and dispersion stabilizers.

[0092] As a polymerization initiator, any suitable photopolymerization initiator can be used depending on the target and desired properties. Specific examples of photopolymerization initiators include: 2,2-dimethoxy-2-phenylacetophenone, acetophenone, benzophenone, xanthones, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, benzoin propyl ether, benzoin dimethyl ether, N,N,N',N'-tetramethyl-4,4'-diaminobenzophenone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 2,4,6-trimethylbenzoyl diphenylphosphine 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. Photopolymerization initiators can be used alone or in combination of two or more. The proportion of photopolymerization initiator relative to 100 parts by weight of the polymerizable liquid crystal component is, for example, 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight.

[0093] Examples of dispersants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. The content of the dispersant in the PDLC layer is, for example, 1% to 15% by weight, preferably 2% to 10% by weight.

[0094] Examples of leveling agents include acrylic leveling agents, fluorinated leveling agents, and silicone leveling agents. The leveling agent content in the PDLC layer is, for example, 0.1% to 10% by weight, preferably 0.5% to 5% by weight.

[0095] Examples of crosslinking agents include aziridine crosslinking agents and isocyanate crosslinking agents. The crosslinking agent content in the PDLC layer is, for example, 0.5% to 20% by weight, preferably 1% to 10% by weight.

[0096] The average particle size of the liquid crystal droplets is typically 1 μm or less, for example, 0.5 μm or less. The scattering of the PDLC layer containing small liquid crystal droplets is reduced; therefore, by making the average particle size of the liquid crystal droplets 1 μm or less, a PDLC film with high transparency in a transparent state can be obtained (e.g., a highly transparent PDLC film in region B when a voltage is applied). From the viewpoint of obtaining higher transparency, the average particle size of the liquid crystal droplets is preferably below the wavelength of visible light. Specifically, the average particle size of the liquid crystal droplets is preferably less than 0.38 μm, more preferably less than 0.3 μm, even more preferably less than 0.2 μm, even more preferably less than 0.18 μm, even more preferably less than 0.15 μm, and even more preferably less than 0.12 μm. The lower limit of the average particle size of the liquid crystal droplets can be, for example, 0.01 μm or more or 0.05 μm or more. The above-mentioned average particle size of the liquid crystal droplets is the volume average particle size of the liquid crystal droplets when viewed from a direction perpendicular to the main surface of the PDLC film, and can be determined, for example, by the method described below.

[0097] <Method for determining the average particle size of liquid crystal droplets in PDLC layers>

[0098] The PDLC film was sliced ​​horizontally in a cooled environment, and the exposed PDLC layer's horizontal cross-section was smoothed using a microtome. Next, the horizontal cross-section of the PDLC layer was observed using a scanning electron microscope (SEM), obtaining a cross-sectional SEM image. The equivalent circular area diameter (Heywood diameter) was calculated based on the cross-sectional area of ​​all liquid crystal droplets in a given region (e.g., a 30 μm × 20 μm region) of the cross-sectional SEM image. The volume average particle size (median particle size) was calculated by weighting the estimated volume for each equivalent diameter.

[0099] 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.

[0100] A-3. Second transparent conductive film

[0101] Typically, the second transparent conductive film 30 has a second transparent substrate 32 and a second transparent electrode layer 34 disposed on one side thereof. The second transparent conductive film 30 may also have a hard coating on one or both sides of the second transparent substrate 32 as needed. In addition, a refractive index adjustment layer may be provided between the second transparent substrate 32 and the second transparent electrode layer 34.

[0102] The surface resistivity of the second transparent conductive film is preferably 1Ω / □ to 1000Ω / □, more preferably 5Ω / □ to 300Ω / □, and even more preferably 10Ω / □ to 200Ω / □.

[0103] 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%.

[0104] 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.

[0105] The same descriptions as those for the first transparent substrate and the first transparent electrode layer apply to the second 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 it may have a different structure.

[0106] A-4. Variation Example 1

[0107] Figure 2 (a) is a top view of an example of a PDLC film according to another embodiment (second embodiment) of the present invention; (b) is a cross-sectional view illustrating the state of the PDLC film shown in (a) when no voltage is applied; and (c) is a cross-sectional view illustrating the state of the PDLC film shown in (a) when a voltage is applied. The PDLC film 100b sequentially includes: a first transparent conductive film 10, a PDLC layer 20 comprising a polymer matrix 22 and liquid crystal droplets 24 dispersed in the polymer matrix 22, and a second transparent conductive film 30.

[0108] The PDLC layer 20 has a first region A and a second region B. The liquid crystal droplets 24 in the first region A contain a non-polymerizable liquid crystal component 24a, a liquid crystal polymer 24c, and a dichroic pigment 24d. The liquid crystal droplets 24 in the second region B contain a non-polymerizable liquid crystal component 24a, a polymerizable liquid crystal component 24b, and a dichroic pigment 24d.

[0109] like Figure 2As shown in (b), in the PDLC film 100b without applied voltage, the liquid crystal polymer 24c in the liquid crystal droplets 24 of region A is oriented along a given direction (thickness direction in the example). Furthermore, the non-polymerizable liquid crystal component 24a and the dichroic pigment 24d are also oriented along the given direction due to the orientation limitation imposed by the liquid crystal polymer 24c. Consequently, in region A, the scattering and absorption of transmitted light are suppressed, haze decreases, and color becomes lighter. On the other hand, the non-polymerizable liquid crystal component 24a, polymerizable liquid crystal component 24b, and dichroic pigment 24d in the liquid crystal droplets 24 of region B are all in a non-oriented state. Consequently, in region B, scattering of transmitted light occurs due to the refractive index difference between the polymer matrix and the liquid crystal component, and absorption occurs due to the dichroic pigment. As a result, in the PDLC film 100b without applied voltage, region A may be colorless and transparent, and region B may be colored and scattering.

[0110] On the other hand, such as Figure 2 As shown in (c), in the PDLC film 100b under applied voltage, the non-polymerizable liquid crystal component 24a, liquid crystal polymer 24c, and dichroic pigment 24d in the liquid crystal droplets 24 of region A are all oriented along a given direction (thickness direction in the example). Furthermore, the non-polymerizable liquid crystal component 24a, polymerizable liquid crystal component 24b, and dichroic pigment 24d in the liquid crystal droplets 24 of region B are also oriented along a given direction (thickness direction in the example). As a result, scattering and absorption of transmitted light are suppressed in both region A and region B, resulting in lower haze and lighter color. Consequently, the main surface of the PDLC film 100b under applied voltage can be entirely colorless and transparent.

[0111] In the PDLC film 100b, the change in haze in region A caused by the application of voltage is less than the aforementioned change in region B, and the difference in haze between region A and region B decreases due to the application of voltage. Furthermore, the transmittance T of the dichroic pigment in region A at the absorption peak wavelength caused by the application of voltage... A The change is less than the transmittance T in region B of the second region. A The change in the transmittance T of region A in the first region. A Transmittance T of region B in the second region A The difference is reduced due to the application of voltage.

[0112] The haze in the first region when no voltage is applied is, for example, 1% to 20%, preferably 1% to 10%. The haze in the first region when voltage is applied is, for example, 1% to 20%, preferably 1% to 10%. The change in haze in the first region caused by the application of voltage (|haze when no voltage is applied - haze when voltage is applied|) is, for example, 0% to 20%, preferably 0% to 10%.

[0113] The haze of the second region without applied voltage is, for example, 50% to 100%, preferably 70% to 100%. The haze of the second region with applied voltage is, for example, 1% to 20%, preferably 1% to 10%. The change in haze of the second region caused by the application of voltage (|haze without applied voltage - haze with applied voltage|) is, for example, 30% to 99%, preferably 60% to 99%.

[0114] The amount of haze change in the first region caused by the application of voltage is less than the amount of haze change in the second region caused by the application of voltage, and the difference is, for example, 10% to 99%, preferably 30% to 99%.

[0115] The transmittance T of the PDLC film in the regions corresponding to region 1 and region 2 when no voltage is applied. A The specific formulation can vary depending on the type and ratio of dichroic pigments, and can be appropriately adjusted according to the intended purpose.

[0116] Transmittance T of region 1 without applied voltage A For example, 45% to 95%, preferably 65% ​​to 95%. The transmittance T of the first region when voltage is applied. A For example, 45% to 95%, preferably 65% ​​to 95%. The transmittance T of the first region caused by the application of voltage. A The change in transmittance (T without applied voltage) A - Transmittance T when voltage is applied A For example, it can be 0%~10%, or 0%~5%.

[0117] Transmittance T of the second region when no voltage is applied A For example, 40% to 90%, preferably 40% to 70%. The transmittance T of the second region when voltage is applied. A For example, 45% to 95%, preferably 60% to 95%. The transmittance T of the second region caused by the application of voltage. A The change in transmittance (T without applied voltage) A - Transmittance T when voltage is applied A For example, it is 5%~30%, and another example is 5%~20%.

[0118] The transmittance T of region 1 caused by the application of voltage A The change in the transmittance T of the second region caused by the application of voltage A The difference in the amount of change is, for example, 5% to 25%, or, for example, 5% to 20%.

[0119] The thickness of the PDLC film is, for example, 30 μm to 250 μm, preferably 50 μm to 150 μm.

[0120] Regarding the PDLC film of the second embodiment, the same descriptions as those for the first and second transparent conductive films in the PDLC film of the first embodiment can be applied to the first and second transparent conductive films, respectively. Furthermore, regarding the PDLC layer, except that the liquid crystal polymer contained in the liquid crystal droplets in the first region is oriented along a given direction, the same descriptions as those for the PDLC layer in the PDLC film of the first embodiment can be applied.

[0121] When no voltage is applied, the liquid crystal polymer contained in the liquid crystal droplet is oriented along a given direction in the first region of the PDLC layer. The orientation direction of the liquid crystal polymer is preferably exemplified by the thickness direction and a direction orthogonal to the thickness direction. The thickness direction can be a direction forming an angle of, for example, 90°±5°, preferably 90°±3°, with respect to the main surface of the transparent conductive films 10, 30.

[0122] A-5. Variation Example 2

[0123] Another embodiment of the PDLC film of the present invention further includes a reflective layer disposed on the side of the PDLC film opposite to the visible side (specifically, the side of the first transparent conductive film or the second transparent conductive film opposite to the side on which the PDLC layer is disposed). When the PDLC film having this configuration is viewed from the visible side, light incident from the visible side, absorbed (colored) and scattered in the PDLC layer, and reflected in the reflective layer can be observed in the colorless transparent region. Thus, the PDLC film can exhibit a transparent appearance in the colorless transparent region. On the other hand, in the colored scattering region, light incident on the PDLC film and reflected in the reflective layer is absorbed (colored) and scattered in the PDLC layer. Thus, the PDLC film can exhibit a colored, opaque, matte appearance in the colored scattering region.

[0124] Figure 3(a) and (b) are cross-sectional schematic diagrams illustrating an example of the PDLC film of this embodiment in the state without voltage and in the state with voltage applied, respectively. The PDLC film 100c sequentially includes: a reflective layer 40, a first transparent conductive film 10, a PDLC layer 20, and a second transparent conductive film 30. In this case, the second transparent conductive film 30 side of the PDLC film 100c is the visible side. The reflective layer 40 is laminated onto the first transparent conductive film, for example, via an adhesive layer, a bonding layer, or other adhesive layer (not shown). In the PDLC film 100c, the PDLC layer 20 has a first region A and a second region B. The first region A is the region where the liquid crystal droplet 24 contains a non-polymerizable liquid crystal component 24a, a liquid crystal polymer 24c, and a dichroic pigment 24d. The second region B is the region where the liquid crystal droplet 24 contains a non-polymerizable liquid crystal component 24a, a polymerizable liquid crystal component 24b, and a dichroic pigment 24d.

[0125] like Figure 3 As shown in (a), in the PDLC film 100c without applied voltage, both the first region A and the second region B of the PDLC layer 20 are in a colored scattering state. Therefore, if the PDLC film 100c without applied voltage is viewed from the visible side, a colored, opaque, matte appearance will be observed across the entire surface. On the other hand, as... Figure 3 As shown in (b), in the PDLC film 100c under applied voltage, the first region A of the PDLC layer 20 is in a colored scattering state, and the second region B is in a colorless and transparent state. Therefore, if the PDLC film 100c under applied voltage is observed from the visible side, a colored, opaque, matte appearance will be observed in the first region A, and a transparent appearance with high transparency, no coloring, or light coloring will be observed in the second region B.

[0126] The configuration of the PDLC layer 20 is not limited to the example shown in the figure above. The PDLC layer 20 can have the same configuration as the PDLC layer 20 contained in the PDLC film 100b, or it can be composed of a liquid crystal component with negative dielectric anisotropy.

[0127] The reflective layer reflects light incident from the visible side of the PDLC film. The reflective layer can also be transmissive; that is, it can be a semi-transmissive reflective layer.

[0128] The total light reflectivity of the reflective layer is, for example, 50% or more, preferably 60% or more, and more preferably 70% to 95%.

[0129] When the reflective layer is transmissive, its total light reflectivity can be, for example, 30% to 60%, preferably 40% to 50%, and its total light transmittance can be, for example, 40% to 70%, preferably 50% to 60%.

[0130] As a reflective layer, any suitable configuration can be adopted. For example, the reflective layer can be a specular reflective layer or a diffuse reflective layer. By using a specular reflective layer, the appearance variation of the PDLC film in the colorless transparent state and the colored scattering state can be increased. The specular reflectivity of the reflective layer can be, for example, 25% or more, preferably 40% to 95%. In addition, by using a reflective layer with a metallic luster, a metallic luster can be imparted to the appearance of the PDLC film.

[0131] Specific examples of reflective layers include resin sheets with high reflectivity (such as acrylic sheets), thin metal sheets or foils such as aluminum and stainless steel, vapor-deposited sheets obtained by vapor depositing aluminum, silver, etc. on substrates such as polyester resin films, laminates of substrates such as polyester resin films and metal foils such as aluminum, and resin films with cavities (voids) formed inside.

[0132] The thickness of the reflective layer can be appropriately set according to the application and other factors. For example, the thickness of the reflective layer is 20μm to 300μm, preferably 30μm to 100μm.

[0133] B. Manufacturing method of polymer-dispersed liquid crystal film

[0134] The PDLC film described in section A can be manufactured by any suitable manufacturing method. In one embodiment, the method for manufacturing the PDLC film includes:

[0135] (Step A) A coating liquid containing a polymer matrix forming resin, a non-polymerizable liquid crystal component, a polymerizable liquid crystal component, a dichroic pigment and a solvent is applied to the first transparent conductive film to obtain a coating layer.

[0136] (Step B) The coating layer is dried to obtain a PDLC layer containing a polymer matrix and liquid crystal droplets dispersed in the polymer matrix, wherein the liquid crystal droplets contain non-polymerizable liquid crystal components, polymerizable liquid crystal components and dichroic pigments.

[0137] (Process C) A second transparent conductive film is laminated on the PDLC layer; and

[0138] (Step D) The PDLC layer is irradiated with active energy rays in a given pattern to form a first region containing liquid crystal droplets, the liquid crystal droplets containing non-polymerizable liquid crystal components, liquid crystal polymers as polymerizable liquid crystal components, and dichroic pigments.

[0139] According to the above-described method for manufacturing a PDLC film, a PDLC layer having a first region and a second region can be formed. The first region is a region in which the liquid crystal droplet contains a non-polymerizable liquid crystal component, a liquid crystal polymer, and a dichroic pigment. The second region is a region in which the liquid crystal droplet contains a non-polymerizable liquid crystal component, a polymerizable liquid crystal component, and a dichroic pigment. As a result, the PDLC film described in item A can be suitably obtained.

[0140] In one embodiment, the active energy irradiation in step D is performed without applying a voltage between the first transparent conductive film and the second transparent conductive film. In another embodiment, the active energy irradiation in step D is performed with a voltage applied between the first transparent conductive film and the second transparent conductive film.

[0141] B-1. Process A

[0142] In step A, a coating liquid comprising a polymer matrix forming resin, a non-polymerizable liquid crystal component, a polymerizable liquid crystal component, a dichroic pigment, and a solvent is applied to the first transparent conductive film to obtain a coating layer.

[0143] The coating liquid described above is preferably an emulsion (hereinafter sometimes referred to as "emulsion coating liquid") consisting of liquid crystal particles containing a non-polymerizable liquid crystal component, a polymerizable liquid crystal component, and a dichroic pigment dispersed in a solvent. In one embodiment, the coating liquid is an emulsion coating liquid consisting of polymer matrix forming resin particles and liquid crystal particles dispersed in a solvent, wherein the liquid crystal particles contain a non-polymerizable liquid crystal component, a polymerizable liquid crystal component, and a dichroic pigment. The emulsion coating liquid preferably further contains a polymerization initiator, and, depending on the purpose, may further contain any suitable additives.

[0144] As a solvent, water or a mixture of water and water-mixed organic solvents are preferred. Examples of water-mixed organic solvents include C1-3 alcohols, acetone, and DMSO. Regarding the resin for forming the polymer matrix, the non-polymerizable liquid crystal component, the polymerizable liquid crystal component, the dichroic pigment and additives, and their proportions, as described in section A.

[0145] The average particle size of the liquid crystal particles is typically 1 μm or less, for example, 0.5 μm or less, preferably less than 0.38 μm, more preferably less than 0.3 μm, even more preferably less than 0.2 μm, even more preferably less than 0.18 μm, even more preferably less than 0.15 μm, even more preferably less than 0.12 μm, and for example, it can be 0.01 μm or more or 0.05 μm or more. The average particle size of the liquid crystal particles described above is the volume average particle size.

[0146] The liquid crystal particles preferably have a relatively narrow particle size distribution. The coefficient of variation (CV value) of the liquid crystal particles can be less than 0.4, preferably less than 0.35, and more preferably less than 0.3.

[0147] The average particle size of the resin particles used for forming the 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 with different average particle sizes can be used. The average particle size of the resin particles used for forming the polymer matrix refers to the volume-average median particle size, which can be measured using a dynamic light scattering particle size distribution measuring device.

[0148] Emulsion coating solutions can be prepared, for example, by mixing a resin emulsion or resin solution containing resin particles for forming a polymer matrix, a liquid crystal emulsion containing liquid crystal particles, and any additives. Solvents can be further added during mixing if necessary. Alternatively, emulsion coating solutions can also be prepared by adding a non-polymerizable liquid crystal component, a polymerizable liquid crystal component, a dichroic pigment, resin particles for forming a polymer matrix, and any additives to a solvent and dispersing them mechanically.

[0149] The aforementioned resin emulsions and liquid crystal emulsions can be prepared, for example, by mechanical emulsification, microchannel method, or membrane emulsification. Liquid crystal emulsions are preferably prepared by membrane emulsification. Membrane emulsification allows for the preparation of emulsions with a suitable uniform particle size distribution. For details regarding membrane emulsification, please refer to the disclosures in Japanese Patent Application Publication No. 4-355719 and Japanese Patent Application Publication No. 2015-40994 (which are incorporated herein by reference).

[0150] The concentration of solid components in the emulsion application solution can be, for example, 20% to 60% by weight, preferably 30% to 50% by weight.

[0151] The viscosity of the emulsion coating solution can be appropriately adjusted to allow for suitable coating of the first transparent conductive film. The viscosity of the emulsion coating solution during coating is preferably 20 mPa·s to 400 mPa·s, more preferably 30 mPa·s to 300 mPa·s, and even more preferably 40 mPa·s to 200 mPa·s. When the viscosity is less than 20 mPa·s, solvent convection becomes significant during drying, potentially leading to instability in the thickness of the PDLC layer. Furthermore, when the viscosity exceeds 400 mPa·s, there is a risk of instability in the emulsion coating solution. The viscosity of the emulsion coating solution can be measured, for example, using a rheometer MCR302 manufactured by Anton Paar. The viscosity used here is the shear viscosity value under conditions of 20°C and a shear rate of 1000 (1 / s).

[0152] Typically, the emulsion coating solution is applied to the transparent electrode layer side surface of the first transparent conductive film. Regarding the first transparent conductive film, it is as described in section A.

[0153] As a coating method, any suitable method can be used. Examples include: roller coating, spin coating, wire rod coating, dip coating, die coating, curtain coating, spray coating, and blade coating (such as comma coating). Among these, roller coating is preferred. For example, regarding coating based on roller coating using a slit die, please refer to the description in Japanese Patent Application Publication No. 2019-5698.

[0154] The thickness of the coating layer is preferably 3μm to 40μm, more preferably 4μm to 30μm, and even more preferably 5μm to 20μm. If it is within this range, a PDLC layer with excellent thickness uniformity can be obtained.

[0155] B-2. Process B

[0156] In step B, the coating layer is dried to obtain a PDLC layer comprising a polymer matrix and liquid crystal droplets dispersed in the polymer matrix. The liquid crystal droplets comprise non-polymerizable liquid crystal components, polymerizable liquid crystal components, and dichroic pigments. The solvent is removed from the coating layer by drying, thereby forming a PDLC layer having a structure in which liquid crystal droplets are dispersed in a polymer matrix.

[0157] The coating layer can be dried by any suitable method. Specific examples of drying methods include natural drying, heat drying, and hot air drying. When the emulsion coating liquid contains a crosslinking agent, a crosslinked structure of the polymer matrix can be formed during drying.

[0158] The drying temperature is preferably 20℃~150℃, more preferably 25℃~80℃. The drying time is preferably 1 minute~100 minutes, more preferably 2 minutes~10 minutes.

[0159] B-3. ​​Process C

[0160] In step C, a second transparent conductive film is laminated on the PDLC layer. Thus, a PDLC film having a first transparent conductive film, a PDLC layer, and a second transparent conductive film in sequence can be obtained.

[0161] Regarding the second conductive film, as described in section A, the second transparent conductive film is laminated on the PDLC layer such that the second transparent electrode layer side is opposite to the PDLC layer. From the viewpoint of obtaining sufficient adhesion, this lamination is preferably performed simultaneously using a laminator with a lamination pressure of 0.006 MPa / m to 7 MPa / m, more preferably 0.06 MPa / m to 0.7 MPa / m.

[0162] B-4. Process D

[0163] In step D, the PDLC layer is irradiated with active energy rays in a given pattern to form a first region containing liquid crystal droplets. These liquid crystal droplets contain a non-polymerizable liquid crystal component, a liquid crystal polymer (a polymerization product of the polymerizable liquid crystal component), and a dichroic pigment. Specifically, in the irradiated region (irradiated region), the polymerizable liquid crystal component in the liquid crystal droplets polymerizes to form a liquid crystal polymer, resulting in liquid crystal droplets containing a non-polymerizable liquid crystal compound, a liquid crystal polymer, and a dichroic pigment. Conversely, in the unirradiated region (non-irradiated region), the polymerizable liquid crystal component remains unreacted, resulting in liquid crystal droplets containing a non-polymerizable liquid crystal component, a polymerizable liquid crystal component, and a dichroic pigment. Thus, the irradiated region of the PDLC layer becomes region A, and the non-irradiated region becomes region B. The liquid crystal polymer contained in the liquid crystal droplets in region A is a polymerization product of the polymerizable liquid crystal component contained in the liquid crystal droplets in region B. It should be noted that the content ratio of non-polymerizable liquid crystal components, polymerizable liquid crystal components, and dichroic pigments in the liquid crystal droplets in the non-irradiated area can basically correspond to the content ratio at the beginning of the formation of the liquid crystal droplets, that is, it can basically correspond to the content ratio of non-polymerizable liquid crystal components, polymerizable liquid crystal components, and dichroic pigments in the coating solution.

[0164] Irradiation with active energy rays is performed via a photomask of a given pattern. Active energy rays can be ultraviolet light, infrared light, X-rays, alpha rays, beta rays, gamma rays, and electron beams, among others. Ultraviolet light is preferred. Furthermore, the active energy rays are preferably collimated light with high linearity from the irradiation source.

[0165] The ultraviolet irradiation conditions can be appropriately set according to the type of polymerizable liquid crystal component, the transmittance of the transparent conductive film, and the absorption wavelength of the photopolymerization initiator. For example, the irradiation intensity can be 0.1 mW / cm². 2 ~1000mW / cm 2 The preferred value is 1mW / cm 2 ~100mW / cm 2 The irradiation dose can be, for example, 10 mJ / cm². 2 ~10000mJ / cm 2 The preferred value is 100 mJ / cm. 2 ~5000mJ / cm 2 The irradiation temperature can be, for example, -20℃ to 80℃, preferably -20℃ to 60℃.

[0166] Figure 4 and Figure 5These are schematic diagrams illustrating an example of active energy ray irradiation in the method for manufacturing a PDLC film according to an embodiment of the present invention. Figure 4 In the illustrated embodiment, irradiation with active energy rays is performed via photomask 200 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 of the irradiation region of the PDLC layer 20, the polymerizable liquid crystal component 24b polymerizes in a non-oriented state; therefore, the formed liquid crystal polymer 24c also becomes non-oriented. Thus, according to this embodiment, the PDLC film 100a described in item A can be suitably obtained.

[0167] exist Figure 5 In the illustrated embodiment, irradiation with active energy rays is performed via a photomask 200 while a voltage is applied between the first transparent conductive film 10 and the second transparent conductive film 30. According to this embodiment, in the liquid crystal droplets 24 of the irradiated region of the PDLC layer 20, the polymerizable liquid crystal component 24b polymerizes in a given direction (thickness direction in the example) along the electric field, thus forming a liquid crystal polymer 24c with its orientation immobilized. Therefore, according to this embodiment, the PDLC film 100b described in item A can be suitably obtained. It should be noted that the voltage applied during irradiation with active energy rays is not limited as long as the desired orientation (in other words, the desired haze in the first region) can be achieved; for example, it can be 10V to 200V, preferably 20V to 100V.

[0168] In one embodiment, by irradiating the PDLC film with active energy rays using a photomask having multiple light-transmitting portions with different aperture ratios, a first region can be formed in the region corresponding to each light-transmitting portion at a ratio corresponding to that aperture ratio. Thus, in the resulting PDLC film, the region corresponding to each light-transmitting portion can display a haze corresponding to its aperture ratio throughout the entire view.

[0169] For example, by irradiating the film with active energy rays without applying voltage using a photomask whose aperture ratio increases continuously from the right end to the left end, a PDLC film can be obtained that exhibits a colored scattering state across the entire surface when no voltage is applied, and displays an appearance where haze and color intensity continuously increase from the right end to the left end when a voltage is applied. Alternatively, for example, by irradiating the film with active energy rays while applying voltage using a photomask whose aperture ratio increases continuously from the right end to the left end, a PDLC film can be obtained that exhibits a colorless and transparent state across the entire surface when a voltage is applied, and displays an appearance where haze and color intensity continuously decrease from the right end to the left end when no voltage is applied.

[0170] Example

[0171] The present invention will now be described in detail with reference to the embodiments, but the present invention is not limited to these embodiments in any way. The methods for measuring each characteristic are described below. In addition, unless otherwise explicitly stated, "parts" and "%" in the embodiments and comparative examples are based on weight.

[0172] (1) Thickness

[0173] The measurements were performed using a digital micrometer (manufactured by Anritsu, product name "KC-351C").

[0174] (2) Volume average particle size of liquid crystal particles in liquid crystal emulsion

[0175] The volume average particle size was calculated using a particle size distribution measuring device (manufactured by Microtrac Corporation, "MT3300EXII").

[0176] (3) Average particle size of resin particles

[0177] A few drops of resin dispersion were added to 100 mL of water to prepare the test sample. Using a dynamic light scattering particle size distribution analyzer (Microtrac, device name "Nanotrac 150"), the test sample was placed on the measuring rack of the device, and the concentration was measured after confirming it was measurable by monitoring the device's monitor.

[0178] (4) Haze

[0179] Measurements were performed using a haze meter (manufactured by Nippon Denshoku Co., Ltd., product name "NDH4000") based on JIS K 7136.

[0180] (5) Transmittance

[0181] Measurements were performed using a UV-Vis-NIR spectrophotometer (manufactured by Hitachi High-Tech Co., Ltd., product name "UH4150") based on JIS K 7361.

[0182] [Example 1]

[0183] (First and second transparent conductive films)

[0184] An ITO layer was formed on one side of a PET substrate (thickness: 50 μm) by sputtering, resulting in a transparent conductive film with a structure of [transparent substrate / transparent electrode layer].

[0185] (Preparation of lotion application solution)

[0186] A liquid crystal emulsion was prepared by mixing 53.7 parts of a non-polymerizable liquid crystal component (manufactured by 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 component (manufactured by BASF Corporation, product name "PALIOCOLOR LC-242"), 0.1 parts of a dichroic pigment (manufactured by Hayashibara Corporation, product name "G470"), 0.1 parts of a photopolymerization initiator (manufactured by IGM Corporation, product name "OMNIRAD651"), 39.8 parts of pure water, and 0.5 parts of a dispersant (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., "Noigen ET159"), and stirring the mixture at 100 rpm for 10 minutes using a homogenizer. The average particle size of the liquid crystal particles in the obtained liquid crystal emulsion was 3.4 μm.

[0187] The above liquid crystal emulsion (38.4 parts), polyether polyurethane resin aqueous dispersion (manufactured by DSM Corporation, trade name "NeoRez R967", average polymer particle size: 80 nm, CV value = 0.27, solid content: 40 wt%) (19.1 parts), polyester polyurethane resin aqueous dispersion (manufactured by Sanyo Chemical Co., Ltd., trade name "UCOAT C-102", average polymer particle size: 168 nm, CV value = 0.23, solid content: 45 wt%) (17.0 parts), leveling agent (manufactured by DIC Corporation, product name "F-444") (0.1 parts), crosslinking agent (propylidynetrimethyl tris[3-(2-methylaziridin-1-yl)propionate]), and pure water (24.3 parts) were mixed to obtain the emulsion coating solution (solid content concentration: 40 wt%).

[0188] (Application and drying of emulsion)

[0189] The above-mentioned emulsion coating solution was applied to the ITO layer of the first transparent conductive film to form a coating layer with a thickness of 20 μm. The coating was performed using a slit die at a linear speed of 6 m / min. The coating layer was then dried at 25°C for 8 minutes, thereby forming a PDLC layer with a thickness of 8 μm.

[0190] (Layering of the second transparent conductive film)

[0191] A second transparent conductive film was laminated on the PDLC layer using a laminator and a lamination pressure of 0.4 MPa / m, with the ITO layer facing the PDLC layer, thereby obtaining the PDLC film.

[0192] (Irradiation by active energy rays)

[0193] On both sides of the PDLC film, a portion of the transparent conductive film is cut in half to the transparent substrate, exposing the transparent electrode layer. The exposed portion is removed and used as an electrode. A photomask with a given pattern is placed on the PDLC film after electrode treatment, and a voltage of 50V is applied while a UV-LED lamp (manufactured by Hamamatsu Photonics, product name "C11924-101", peak wavelength 365nm) is used at 10mW / cm². 2 The film underwent a 10-minute exposure process. When no voltage was applied, the PDLC film exhibited a colorless and transparent state in the irradiated area and a colored and scattering state in the unirradiated area.

[0194] [Example 2]

[0195] The PDLC film was obtained by ultraviolet irradiation without applying voltage (applied voltage: 0V), otherwise, the same procedure as in Example 1 was followed. The obtained PDLC film exhibited colored scattering in both the irradiated and unirradiated areas when no voltage was applied.

[0196] For the PDLC film obtained in the examples, the haze and transmittance of the irradiated and non-irradiated areas were measured using an AC power supply “EC750SA” manufactured by NF Circuit Design Co., Ltd. when an AC voltage of 0V to 50V was applied to the PDLC film.

[0197] As a result, in Example 1, the PDLC film exhibited a significant reduction in haze and coloration in the non-irradiated area due to the application of voltage, while both the irradiated and non-irradiated areas became colorless and transparent. Furthermore, in Example 2, the PDLC film also showed a significant reduction in haze and coloration in the non-irradiated area due to the application of voltage, becoming colorless and transparent, while the irradiated area maintained its color scattering state. These findings confirm that in the PDLC films obtained in the examples, the changes in haze caused by voltage application and the changes in transmittance of the dichroic pigment at the absorption peak wavelength (432 nm) in the first region (irradiated region) were both less than those in the second region (non-irradiated region).

[0198] Industrial applicability

[0199] The PDLC film of the present invention is suitable for various applications such as displays for advertising, guide panels, and smart windows.

Claims

1. A polymer-dispersed liquid crystal film, comprising, in sequence: First transparent conductive film, A polymer-dispersed liquid crystal layer comprising a polymer matrix and liquid crystal droplets dispersed in the polymer matrix, and The second transparent conductive film, The polymer-dispersed liquid crystal layer has a first region and a second region. The first region is the region in which the liquid crystal droplet contains non-polymerizable liquid crystal components, liquid crystal polymers, and dichroic pigments. The second region is the region in which the liquid crystal droplet contains non-polymerizable liquid crystal components, polymerizable liquid crystal components, and dichroic pigments.

2. The polymer-dispersed liquid crystal film according to claim 1, wherein, The change in transmittance of the dichroic pigment in the first region at the absorption peak wavelength caused by the application of voltage is less than the change in transmittance in the second region.

3. The polymer-dispersed liquid crystal film according to claim 1, wherein, The average particle size of the liquid crystal droplets is less than 1 μm.

4. The polymer-dispersed liquid crystal film according to claim 1, wherein, In the first region, the liquid crystal polymer is present in a proportion of 1 to 30 parts by weight relative to 100 parts by weight of the non-polymerizable liquid crystal component.

5. The polymer-dispersed liquid crystal film according to claim 1, wherein, In the first region, the dichroic pigment is present in a proportion of 0.1 to 10 parts by weight relative to 100 parts by weight of the nonpolymeric liquid crystal component.

6. The polymer-dispersed liquid crystal film according to claim 1, wherein, The difference in haze between the first region and the second region increases due to the application of voltage.

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

8. The polymer-dispersed liquid crystal film according to claim 1, wherein, A reflective layer is further included on the side opposite to the side where the polymer-dispersed liquid crystal layer is disposed on the first transparent conductive film or the second transparent conductive film.

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