Optical film and method for producing optical film

Abstract

The present invention provides an optical film that has a diffusion layer containing a polymer matrix and dispersed particles that are dispersed in the polymer matrix, the dispersed particles containing a liquid crystal polymer which is a polymer of a polymerizable liquid crystal compound. The diffusion layer has multiple regions having different states of orientation of said liquid crystal polymer and / or different content ratios of said liquid crystal polymer.

Description

Optical film and method for producing the same

[0001] The present invention relates to an optical film having a diffusion layer and a method for producing the optical film.

[0002] A PDLC film having 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 be switched between a light scattering state (scattering state) and a light transmitting state (non-scattering state or transparent state) by switching between a voltage applied state and a voltage not applied state. Specifically, the PDLC layer includes a polymer matrix and droplets of a liquid crystal compound (hereinafter sometimes referred to as "liquid crystal droplets") dispersed in the polymer matrix, and the liquid crystal droplets act as scattering particles, causing light scattering due to the difference in refractive index between the liquid crystal compound in the liquid crystal droplets and the polymer matrix, etc.

[0003] By utilizing the scattering effect, the PDLC film can be used as a diffuser. For example, Patent Document 1 proposes that a PDLC film including areas with high and low scattering degrees is produced by varying the ultraviolet irradiation intensity depending on the location during the production of a polymer matrix, and that the PDLC film is used as a diffuser for a direct backlight.

[0004] However, with the technique disclosed in Patent Document 1, it is difficult to form a fine pattern having areas with a high degree of scattering and areas with a low degree of scattering.

[0005] JP 2011-008005 A

[0006] A primary object of the present invention is to provide an optical film having a diffusion layer, which has regions with different degrees of scattering in a desired pattern.

[0007] According to one aspect of the present invention, there is provided an optical film having a diffusion layer including a polymer matrix and dispersed particles containing a liquid crystal polymer, which is a polymer of a polymerizable liquid crystal compound, dispersed in the polymer matrix, the diffusion layer having a plurality of regions differing in the orientation state of the liquid crystal polymer and / or the content ratio of the liquid crystal polymer. In one embodiment, the plurality of regions are arranged in a predetermined pattern. In one embodiment, the maximum difference in haze between the plurality of regions in a plan view is 10% or more. In one embodiment, the dispersed particles further contain a liquid crystal compound. In one embodiment, the content ratio of the liquid crystal polymer relative to the total content of the liquid crystal polymer and the liquid crystal compound is 5% by weight or more. In one embodiment, the total content ratio of the liquid crystal polymer and, if present, the liquid crystal compound in the diffusion layer is 30% by weight to 70% by weight. In one embodiment, a first transparent substrate is disposed on the first major surface side of the diffusion layer. In one embodiment, a second transparent substrate is disposed on the second major surface side of the diffusion layer.

[0013] In one embodiment, the optical film does not have an electrode layer. According to another aspect of the present invention, there is provided an optical film having a diffusion layer including a polymer matrix and dispersed particles containing a liquid crystal polymer that is a polymer of a polymerizable liquid crystal compound, the diffusion layer having, in a planar view, a plurality of regions that exhibit different hazes depending on the orientation state of the liquid crystal polymer. According to another aspect of the present invention, there is provided an optical film having a diffusion layer including a polymer matrix and dispersed particles that are dispersed in the polymer matrix, the diffusion layer having a region containing dispersed particles containing a polymerizable liquid crystal compound and a region containing dispersed particles containing a liquid crystal polymer that is a polymer of the polymerizable liquid crystal compound, the diffusion layer having ...According to another aspect of the present invention, there is provided a method for producing an optical film, the method comprising: applying a coating liquid containing a polymer matrix-forming resin, a polymerizable liquid crystal compound, and a solvent to a first substrate to obtain a coating layer; drying the coating layer to obtain a polymer-dispersed liquid crystal layer containing a polymer matrix and droplets containing the polymerizable liquid crystal compound dispersed in the polymer matrix; and polymerizing the polymerizable liquid crystal compound while applying voltages from a first major surface side and a second major surface side of the polymer-dispersed liquid crystal layer so as to create regions of different electric field strengths. In one embodiment, the voltage application is performed using a first electrode arranged on the first major surface side of the polymer-dispersed liquid crystal layer and a second electrode arranged on the second major surface side, and controlling the distance between the first electrode and the second electrode so as to create the regions of different electric field strengths. According to another aspect of the present invention, there is provided a method for producing an optical film, comprising: applying a coating liquid containing a polymer matrix-forming resin, a polymerizable liquid crystal compound, and a solvent to a first substrate to obtain a coating layer; drying the coating layer to obtain a polymer-dispersed liquid crystal layer containing a polymer matrix and droplets containing the polymerizable liquid crystal compound dispersed in the polymer matrix; and irradiating a predetermined region of the polymer-dispersed liquid crystal layer with active energy rays while applying a voltage to the polymer-dispersed liquid crystal layer to polymerize the polymerizable liquid crystal compound. In one embodiment, the coating liquid is an emulsion containing liquid crystal particles containing the polymerizable liquid crystal compound as a dispersoid. In one embodiment, the coating liquid further contains a non-polymerizable liquid crystal compound.

[0008] An optical film according to an embodiment of the present invention has a diffusion layer including a polymer matrix and dispersed particles containing a liquid crystal polymer, which is a polymer of a polymerizable liquid crystal compound, dispersed in the polymer matrix. The diffusion layer has multiple regions with different orientation states and / or liquid crystal polymer content. Since the dispersed particles can exhibit different scattering properties depending on the orientation state and / or content of the liquid crystal polymer contained therein, in an optical film having such a configuration, each of the multiple regions can exhibit a different degree of scattering depending on the orientation state and / or content of the liquid crystal polymer. Therefore, by adjusting the orientation state and / or content of the liquid crystal polymer to obtain a desired pattern, an optical film can be obtained that has regions with different scattering degrees in a desired pattern.

[0009] FIG. 1A is a schematic plan view of an example of an optical film according to an embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view of the optical film shown in FIG. 1A. FIG. 1B is a schematic cross-sectional view of an example of an optical film according to an embodiment of the present invention. FIG. 1C is a schematic cross-sectional view of an example of an optical film according to another embodiment of the present invention. FIG. 1D is a schematic cross-sectional view of an example of an optical film according to an embodiment of the present invention. FIG. 1F is a schematic cross-sectional view of an electrode having a convex portion. FIG. 1G is a schematic cross-sectional view of an example of an optical film according to another embodiment of the present invention.

[0010] 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.

[0011] A. Optical Film According to a first embodiment of the present invention, an optical film is provided having a diffusion layer including a polymer matrix and dispersed particles containing a liquid crystal polymer, which is a polymer of a polymerizable liquid crystal compound, dispersed in the polymer matrix, the diffusion layer having multiple regions with different orientation states of the liquid crystal polymer. The dispersed particles may further contain a liquid crystal compound. The liquid crystal compound may be oriented along the liquid crystal polymer within the dispersed particles. Therefore, the dispersed particles can exhibit different scattering properties depending on the orientation state of the liquid crystal polymer contained therein, and an optical film having such a configuration can exhibit a degree of scattering (haze) in the multiple regions depending on the orientation state of the liquid crystal polymer. Therefore, in the optical film of the first embodiment, when the optical film (more specifically, the diffusion layer) has multiple regions with different degrees of scattering (haze) in a planar view, it can be said that "the diffusion layer has multiple regions with different orientation states of the liquid crystal polymer." Furthermore, the optical film of the first embodiment may be an optical film having a diffusion layer containing a polymer matrix and dispersed particles that are dispersed in the polymer matrix and contain a liquid crystal polymer that is a polymer of a polymerizable liquid crystal compound, and having, in a planar view, a plurality of regions that exhibit different hazes depending on the orientation state of the liquid crystal polymer.

[0012] A-1. Configuration of Optical Film FIG. 1(a) is a schematic plan view of an example of an optical film according to a first embodiment, and FIG. 1(b) is a schematic cross-sectional view of the optical film shown in FIG. 1(a). The optical film 100a is composed of a polymer matrix 12 and a diffusion layer 10 containing dispersed particles 14, which are dispersed in the polymer matrix 12 and contain a liquid crystal compound 14a and a liquid crystal polymer 14b. The diffusion layer 10 has five regions (A1, A2, B1, B2, and C). Of these regions, the orientation states of the liquid crystal polymer 14b in regions A1 and A2 are the same, the orientation states of the liquid crystal polymer 14b in regions B1 and B2 are the same, and the orientation states of the liquid crystal polymer 14b in regions A1 and A2, regions B1 and B2, and region C are different from one another (the relationship between the orientation states of the respective regions: A1 = A2 ≠ B1 = B2 ≠ C).

[0013] Specifically, the liquid crystal polymer 14b in the dispersed particles 14 is oriented approximately perpendicular to the main surface of the optical film 100a (diffusion layer 10) in regions A1 and A2, is non-oriented in region C, and is oriented in regions B1 and B2 in an intermediate state. Furthermore, the liquid crystal compound 14a in the dispersed particles 14 is oriented along the liquid crystal polymer 14b, and is oriented in a state similar to the orientation state of the liquid crystal polymer 14b. Therefore, the dispersed particles in these multiple regions (A1, A2, B1, B2, C) may exhibit different scattering properties in each region due to differences in the orientation state of the liquid crystal polymer and / or liquid crystal compound. As a result, the optical film 100a, in a planar view, exhibits the smallest haze (diffusion degree) in regions corresponding to regions A1 and A2, the largest haze in region C, and an intermediate haze in regions B1 and B2.

[0014] 2 and 3 are schematic cross-sectional views of another example of the optical film according to the first embodiment (dispersion particles are not shown). An optical film 100b shown in FIG. 2 has a first transparent substrate 20 on the first major surface side of a diffusion layer 10. An optical film 100c shown in FIG. 3 has a first transparent substrate 20 on the first major surface side of a diffusion layer 10 and a second transparent substrate 30 on the second major surface side. The diffusion layer 10 and the first transparent substrate 20 and / or the second transparent substrate 30 may be laminated via an adhesive layer or a pressure-sensitive adhesive layer, or may be laminated directly without an adhesive layer or a pressure-sensitive adhesive layer.

[0015] 1, the dispersed particles 14 contain a liquid crystal compound 14a and a liquid crystal polymer 14b, but the dispersed particles 14 do not necessarily contain the liquid crystal compound 14a. Furthermore, in the optical film according to an embodiment of the present invention, the orientation of the liquid crystal compound in the dispersed particles can be controlled by the liquid crystal polymer, so there is no need to control the orientation of the liquid crystal compound by applying a voltage. Therefore, the optical film according to an embodiment of the present invention does not need to have an electrode layer, regardless of whether the dispersed particles contain a liquid crystal compound.

[0016] In the diffusion layer of the embodiment shown in FIG. 1 , the liquid crystal polymer in the dispersed particles has three orientation states, but the present invention is not limited to this embodiment. Specifically, the orientation state of the liquid crystal polymer is not particularly limited as long as it is two or more. Furthermore, the orientation state of the liquid crystal polymer in multiple regions with different orientation states of the liquid crystal polymer (in other words, the scattering properties of the dispersed particles in the region or the haze of the region) is not limited, and each region may have a desired orientation state independently. Furthermore, the arrangement pattern of these regions is not limited and can be freely designed as a predetermined pattern. Therefore, the above optical film can exhibit a desired haze in a desired pattern.

[0017] In the embodiment shown in FIG. 1 , each of the multiple regions (A1, A2, B1, B2, C) in which the liquid crystal polymer in the dispersed particles has a different orientation state has a certain area, but the region does not need to have an area greater than a predetermined value. For example, in the optical film of the first embodiment, even if the orientation state of the liquid crystal polymer changes continuously in the in-plane direction and a region in a specific orientation state cannot be identified as a region having a certain area in a planar view, the diffusion layer is still considered to have multiple regions in which the liquid crystal polymer has a different orientation state. In one embodiment, when the haze of the optical film (more specifically, the diffusion layer) changes continuously in the in-plane direction in a planar view, the orientation state of the liquid crystal polymer can be considered to change continuously in the in-plane direction.

[0018] When the optical film is viewed in plan, the haze in each of the regions corresponding to the plurality of regions in which the alignment state of the liquid crystal polymer in the dispersed particles is different can be appropriately set depending on the application of the optical film. In one embodiment, the difference between the maximum and minimum haze values ​​in the regions corresponding to the plurality of regions can be, for example, greater than 0%, preferably 10% or more, more preferably 20% to 100%, and even more preferably 30% to 100%. The maximum haze value can be, for example, 30% to 100%, and the minimum haze value can be, for example, 0% to 70%.

[0019] A-2. Diffusion Layer The diffusion layer 10 includes a polymer matrix 12 and dispersed particles 14 containing a liquid crystal polymer 14b, which is a polymer of a polymerizable liquid crystal compound, dispersed in the polymer matrix 12. The dispersed particles 14 have multiple regions in which the liquid crystal polymer 14b has different orientation states. The dispersed particles 14 may further include a liquid crystal compound 14a. For example, in the embodiment shown in FIG. 1, the dispersed particles 14 include a liquid crystal compound 14a and a liquid crystal polymer 14b. The diffusion layer 10 also has regions A1, A2, B1, B2, and C, and the orientation states of the liquid crystal polymer 14b in the dispersed particles 14 in each region satisfy the relationship "A1 = A2 ≠ B1 = B2 ≠ C." That is, the orientation states of the liquid crystal polymer 14b in regions A1 and A2, regions B1 and B2, and region C are different from one another. The liquid crystal compound 14a in the dispersed particles 14 is oriented along the liquid crystal polymer 14b. With this configuration, regions in which the liquid crystal polymer 14b in the dispersed particles 14 has a different orientation state can exhibit different hazes. Therefore, the haze of each region in the diffusion layer 10 can satisfy the relationship "A1=A2≠B1=B2≠C."

[0020] The haze in each of the plurality of regions of the diffusion layer can be appropriately set depending on the application of the optical film, etc. The maximum value, minimum value, and difference between the haze in each of the plurality of regions of the diffusion layer can be set so as to obtain the maximum value, minimum value, and difference between the haze desired for the optical film.

[0021] The polymer matrix 12 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 substrate, 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 polymer matrix-forming resins may be used alone or in combination.

[0022] The content of the polymer matrix in the diffusion layer 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 mechanical strength can be obtained, and effects such as prevention of liquid crystal leakage from the edges can be obtained.

[0023] The liquid crystal polymer 14b is a polymer of a polymerizable liquid crystal compound and is non-liquid crystal, i.e., the liquid crystal polymer does not undergo transition to a liquid crystal phase, glass phase, or crystalline phase due to temperature changes, which is unique to liquid crystal compounds.

[0024] The polymerizable liquid crystal compound constituting the liquid crystal polymer can be appropriately selected depending on factors such as light transmittance and compatibility with the non-polymerizable liquid crystal compound described below. 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, for example, JP-A-2002-533742 (WO 00 / 37585), EP 358208 (US 5,211,877), EP 66137 (US 4,388,453), WO 93 / 22397, EP 0,261,712, DE 19504224, DE 4408171, and GB 2,280,445. A specific example of such a polymerizable mesogenic compound is LC242, a product name of BASF. Nematic liquid crystal monomers are preferred as the polymerizable liquid crystal compound. The birefringence Δn (=ne−no; ne is the refractive index of the liquid crystal compound molecules in the major axis direction, and no is the refractive index of the liquid crystal compound molecules in the minor axis direction) of the polymerizable liquid crystal compound at a wavelength of 589 nm is preferably 0.05 to 0.50, more preferably 0.10 to 0.45.

[0025] Any suitable non-polymerizable liquid crystal compound can be used as the liquid crystal compound 14a. As described in detail in Section B, the diffusion layer can be formed by performing a polymerization reaction while controlling the orientation of a polymerizable liquid crystal compound. In this case, using a non-polymerizable liquid crystal compound in combination with a polymerizable liquid crystal compound widens the temperature range of the liquid crystal phase (e.g., nematic phase), allowing for more suitable orientation control. As the liquid crystal compound, a non-polymerizable 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 is preferably used, and more preferably a birefringence Δn of 0.10 to 0.45 is more preferably used.

[0026] 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.

[0027] 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.

[0028] The total content of the liquid crystal polymer and the liquid crystal compound, if present, in the diffusion layer (the content of the liquid crystal polymer when the liquid crystal compound is not present) is, for example, 30% to 70% by weight, preferably 35% to 65% by weight, and more preferably 40% to 60% by weight. The content of the liquid crystal polymer relative to the total content of the liquid crystal polymer and the liquid crystal compound in the diffusion layer (more specifically, the dispersed particles) is, for example, 5% by weight or more, preferably 7% by weight or more, more preferably 10% by weight or more, and may be, for example, 100% by weight or less, preferably 80% by weight or less, and more preferably 50% by weight or less. The total content of the polymer matrix, the liquid crystal polymer, and the liquid crystal compound, if present, in the diffusion layer may be, for example, 90% by weight to 99.9% by weight, and preferably 95% by weight to 99.9% by weight.

[0029] As described in detail in Section B, the diffusion layer can be formed by preparing a PDLC layer containing liquid crystal droplets containing a polymerizable liquid crystal compound and, optionally, a non-polymerizable liquid crystal compound, and polymerizing the polymerizable liquid crystal compound while applying a voltage from the first principal surface side and the second principal surface side of the PDLC layer so as to create regions of different electric field strength. Therefore, the diffusion layer (more specifically, the dispersed particles) can further contain a polymerization initiator. The content of the polymerization initiator is as described in Section B. Furthermore, unreacted polymerizable liquid crystal compound can remain in the dispersed particles. The content of the unreacted polymerizable liquid crystal compound in the diffusion layer (more specifically, the dispersed particles) is, for example, 3 wt % or less, preferably 1 wt % or less.

[0030] The average particle diameter of the dispersed particles can be, for example, 0.3 μm to 9 μm, preferably 0.4 μm to 8 μm. If the average particle diameter of the dispersed particles is too small, the dispersed particle size is smaller than the wavelength of light, so light passes through the dispersed particles without being scattered, which can result in a problem of insufficient haze being obtained. If the average particle diameter is too large, the dispersed particle size is larger than the wavelength of light, so can a problem of insufficient haze being obtained. Note that the average particle diameter of the dispersed particles in the diffusion layer is the volume-average particle diameter of the dispersed particles when viewed from a direction perpendicular to the main surface of the optical film.

[0031] The thickness of the diffusion layer is typically 2 μm to 40 μm, preferably 3 μm to 35 μm, and more preferably 4 μm to 30 μm.

[0032] A-3. First Transparent Substrate The first transparent substrate 20 includes a first transparent film. The first transparent substrate may have a hard coat layer on one or both sides of the first transparent film, as needed.

[0033] The haze of the first transparent substrate is preferably 20% or less, more preferably 10% or less, and even more preferably 0.1% to 10%.

[0034] 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. The total light transmittance can be measured in accordance with JIS K 7361.

[0035] The first transparent film may be formed using any suitable material. Specific examples include glass films and polymer films. Polymer films are preferred because they have excellent smoothness and can be continuously produced using rolls, significantly improving productivity.

[0036] The polymer film is typically a polymer film containing a thermoplastic resin as a main component. 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 thermoplastic resins may be used alone or in combination of two or more. In addition, 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.

[0037] The total light transmittance of the first transparent film is preferably 30% or more, more preferably 60% or more, and even more preferably 80% or more.

[0038] The thickness of the first transparent film is preferably 200 μm or less, more preferably 3 μm to 150 μm, and even more preferably 5 μm to 100 μm.

[0039] A-4. Second Transparent Substrate The second transparent substrate 30 includes a second transparent film. The second transparent substrate may have a hard coat layer on one or both sides of the second transparent film, as needed.

[0040] The haze of the second transparent substrate is preferably 20% or less, more preferably 10% or less, and even more preferably 0.1% to 10%.

[0041] The total light transmittance of the second transparent substrate is preferably 30% or more, more preferably 60% or more, and even more preferably 80% or more.

[0042] The second transparent film can be described in the same manner as the first transparent film described in Section A-3. The second transparent substrate may have the same structure as the first transparent substrate, or may have a different structure.

[0043] A-5. Second Embodiment According to a second embodiment of the present invention, a polymer film is provided having a diffusion layer including a polymer matrix and dispersed particles containing a liquid crystal polymer, which is a polymer of a polymerizable liquid crystal compound, dispersed in the polymer matrix. The diffusion layer has multiple regions with different liquid crystal polymer content ratios. Typically, the diffusion layer has a region containing dispersed particles containing a liquid crystal polymer and a region containing dispersed particles containing a polymerizable liquid crystal compound. The liquid crystal polymer content ratio in the region containing dispersed particles containing a polymerizable liquid crystal compound is lower than the liquid crystal polymer content ratio in the region containing dispersed particles containing a liquid crystal polymer. The difference in liquid crystal polymer content ratio is not limited as long as the effects of the present invention are achieved. For example, the region containing dispersed particles containing a polymerizable liquid crystal compound may be substantially free of liquid crystal polymer. In such a configuration, the liquid crystal polymer and the polymerizable liquid crystal compound are aligned in different orientations, allowing these regions to exhibit different hazes.

[0044] When the optical film is viewed in plan, the haze in each of the regions corresponding to the plurality of regions having different liquid crystal polymer content ratios can be appropriately set depending on the application of the optical film. In one embodiment, the difference between the maximum and minimum haze values ​​in the regions corresponding to the plurality of regions can be, for example, greater than 0%, preferably 10% or more, more preferably 20% to 100%, and even more preferably 30% to 100%. The maximum haze value can be, for example, 30% to 100%, and the minimum haze value can be, for example, 0% to 70%.

[0045] FIG. 4 is a schematic cross-sectional view of an example of an optical film according to a second embodiment of the present invention. The optical film 100d includes a diffusion layer 10, a first transparent substrate 20 disposed on the first major surface side of the diffusion layer 10, and a second transparent substrate 30 disposed on the second major surface side. The diffusion layer 10 includes a region E including a polymer matrix 12 and first dispersed particles 14 dispersed in the polymer matrix 12 and containing a non-polymerizable liquid crystal compound 14a and a liquid crystal polymer 14b, and regions D1 and D2 including the polymer matrix 12 and second dispersed particles 14' dispersed in the polymer matrix 12 and containing a non-polymerizable liquid crystal compound 14a and a polymerizable liquid crystal compound 14c. The second dispersed particles 14' may be droplets of a liquid crystal compound. In region E, the non-polymerizable liquid crystal compound 14a and the liquid crystal polymer 14b are aligned substantially perpendicular to the major surface. In regions D1 and D2, the non-polymerizable liquid crystal compound 14a and the polymerizable liquid crystal compound 14c are non-aligned. Therefore, in plan view, regions D1 and D2 can exhibit higher haze than region E.

[0046] Regarding the diffusion layer 10, the same explanation as in Section A-2 can be applied to the region containing the first dispersion particles 14. The same explanation as in Section A-2 can be applied to the region containing the second dispersion particles 14', except that the polymerizable liquid crystal compound 14c is contained instead of the liquid crystal polymer 14b. Like the dispersion particles 14, the dispersion particles 14' may not contain the non-polymerizable liquid crystal compound 14a depending on the purpose.

[0047] The descriptions in sections A-3 and A-4 can be applied to the first transparent substrate 20 and the second transparent substrate 30. Depending on the purpose, either or both of the first transparent substrate 20 and the second transparent substrate 30 may be omitted.

[0048] A-6. Uses of Optical Films The optical films according to the embodiments of the present invention can exhibit a desired haze in a desired pattern. Specific examples of uses of the optical films include diffusion films and decorative films.

[0049] A preferred example of the diffusion film is a diffusion film for an image display device, more specifically, a diffusion film for an image display device equipped with a direct backlight. Specifically, for a direct backlight equipped with a plurality of LED light sources arranged at a predetermined interval, by applying an optical film patterned so that the haze is high in the region located directly above the LED light sources and decreases as the distance from the LED light sources increases, it is possible to suitably achieve uniformity of the in-plane luminance distribution.

[0050] A preferred example of the design film is a shielding film that shields wiring and the like provided on the periphery of an image display area in an image display device such as a liquid crystal display device or an organic EL display device. Generally, shielding of wiring and the like is achieved by providing a frame-shaped printed layer on a front panel such as a cover glass or a cover film, either directly or via a substrate film. Such a configuration poses a problem in that the interlayer adhesive cannot fully absorb the difference in thickness between the portion where the printed layer is provided and other portions, which can lead to the formation of air bubbles. However, the optical film according to an embodiment of the present invention provides a smooth, stepless surface between the shielding area (high haze area) and the display area (low haze area), thereby eliminating the problem of air bubbles.

[0051] B. Optical Film Manufacturing Method The optical film manufacturing method according to the first embodiment of the present invention includes: (Step A) applying a coating liquid containing a polymer matrix-forming resin, a polymerizable liquid crystal compound, and a solvent to a first substrate to obtain a coating layer; (Step B) drying the coating layer to obtain a PDLC layer containing a polymer matrix and droplets containing the polymerizable liquid crystal compound dispersed in the polymer matrix; and (Step C) polymerizing the polymerizable liquid crystal compound while applying voltages from the first and second main surfaces of the PDLC layer so as to create regions with different electric field strengths. The optical film manufacturing method according to the first embodiment may optionally further include (Step D) placing a second substrate on the side of the PDLC layer or the diffusion layer opposite the side on which the first substrate is provided, before or after polymerizing the polymerizable liquid crystal compound. According to the optical film manufacturing method according to the first embodiment, the polymerizable liquid crystal compound polymerizes in different orientation states depending on the electric field strength in each region with different electric field strength, resulting in the formation of a diffusion layer having multiple regions with different orientation states of the liquid crystal polymer in the dispersed particles. Therefore, according to the method for producing an optical film according to the first embodiment, the optical film described in section A (specifically, the optical film of the first embodiment) can be suitably obtained.

[0052] B-1. Step A In step A, a coating liquid containing a polymer matrix-forming resin, a polymerizable liquid crystal compound, and a solvent is applied to a first substrate to obtain a coating layer. The coating liquid may further contain a non-polymerizable liquid crystal compound.

[0053] The coating liquid is preferably an emulsion containing, as a dispersoid, liquid crystal particles containing a polymerizable liquid crystal compound and, optionally, a non-polymerizable liquid crystal compound (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 polymerizable liquid crystal compound and, optionally, a non-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.

[0054] As the solvent, water or a mixed solvent of water and a water-miscible organic solvent can be preferably used. Examples of the water-miscible organic solvent include C1-3 alcohol, acetone, and DMSO. The polymerizable liquid crystal compound, non-polymerizable liquid crystal compound, and polymer matrix-forming resin are as described in Section A-2. Optional additives include a dispersant, a leveling agent, and a crosslinking agent.

[0055] The content of the liquid crystal compound in the solid content of the coating liquid (the total content of the polymerizable liquid crystal compound and the non-polymerizable liquid crystal compound, if present) may 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.

[0056] The weight ratio of the polymerizable liquid crystal compound to the non-polymerizable liquid crystal compound in the coating liquid (polymerizable liquid crystal compound:non-polymerizable liquid crystal compound) may be, for example, 5:95 to 100:0, preferably 7:93 to 80:20, and more preferably 10:90 to 50:50.

[0057] The content of the polymer matrix-forming resin in the solid content of the coating liquid may be, for example, 30 to 70% by weight, preferably 35 to 65% by weight, and more preferably 40 to 60% by weight.

[0058] The weight ratio of the content of the liquid crystal compound in the coating liquid (the total content of the polymerizable liquid crystal compound and, if present, the non-polymerizable liquid crystal compound) to the content of the polymer matrix-forming resin (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. Furthermore, the total content of the polymer matrix-forming resin and the polymerizable liquid crystal compound and, if present, the non-polymerizable liquid crystal compound in the solid content of the coating liquid can be, for example, 90% by weight to 99.9% by weight, preferably 95% by weight to 99.9% by weight.

[0059] 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 dispersed particles in the diffusion layer can be set within a desired range. The average particle size of the liquid crystal particles is a volume average particle size.

[0060] 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).

[0061] The average particle size 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 size may be used. The average particle size of the resin particles for forming a polymer matrix means the volume-average median size and can be measured using a dynamic light scattering particle size distribution analyzer.

[0062] As the polymerization initiator, any appropriate photopolymerization initiator or thermal polymerization initiator can be used depending on the purpose, desired properties, etc., and a photopolymerization initiator is preferably used. Specific examples of the photopolymerization initiator 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 polymerization initiators may be used alone or in combination of two or more. The content of the polymerization initiator is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polymerizable liquid crystal compound.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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 polymerizable liquid crystal compound, a polymerization initiator, and optionally a non-polymerizable liquid crystal compound, 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 the polymerizable liquid crystal compound, the polymer matrix-forming resin, the polymerization initiator, and optionally the non-polymerizable liquid crystal compound and additives to a solvent and mechanically dispersing the mixture.

[0067] 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, JP-A-2015-40994, and the like (these are incorporated herein by reference).

[0068] The solid content of the emulsion coating liquid may be, for example, 20% to 60% by weight, and preferably 30% to 50% by weight.

[0069] The viscosity of the emulsion coating liquid can be appropriately adjusted so that application to the first substrate is performed smoothly. 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, solvent convection becomes significant when the solvent is dried, which may cause the thickness of the PDLC layer (and consequently the diffusion layer) to become unstable. Furthermore, 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 an Anton Paar MCR302 rheometer. The viscosity used here is the shear viscosity value at 20°C and a shear rate of 1000 (1 / s).

[0070] Any appropriate substrate can be used as the first substrate. By using the first transparent substrate described in Section A-3 as the first substrate, an optical film having the first transparent substrate and a diffusion layer can be suitably obtained. Depending on the purpose, the first substrate may be peeled off and removed from the diffusion layer after completion of step C.

[0071] 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, with regard to coating by roll coating using a slot die, the description in JP-A-2019-5698 can be referred to.

[0072] 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 this range, a PDLC layer (and consequently a diffusion layer) with excellent thickness uniformity can be obtained.

[0073] B-2. Step B In step B, the coating layer is dried to obtain a PDLC layer containing a polymer matrix and droplets containing a polymerizable liquid crystal compound and, optionally, a non-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 to each other, forming a PDLC layer having a structure in which liquid crystal droplets are dispersed in a polymer matrix.

[0074] The coating layer can be dried by any appropriate method. Specific examples of the drying method include natural drying, 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.

[0075] 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.

[0076] B-3. ​​Step C In step C, the polymerizable liquid crystal compound is polymerized while applying a voltage from the first principal surface side and the second principal surface side of the PDLC layer so as to create regions with different electric field strengths. This forms a diffusion layer containing a polymer matrix and dispersed particles that are dispersed in the polymer matrix and contain a liquid crystal polymer, which is a polymer of the polymerizable liquid crystal compound.

[0077] The polymerization of the polymerizable liquid crystal compound is carried out by irradiation with active energy rays, heating, or a combination thereof, and is preferably carried out by irradiation with active energy rays.

[0078] Examples of active energy rays that can be used include ultraviolet rays, infrared rays, X-rays, α rays, β rays, γ rays, and electron beams. Of 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.

[0079] The ultraviolet irradiation conditions can be appropriately set depending on the type of polymerizable liquid crystal compound, the transmittance of the substrate, 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 ~10000mJ / cm ２ , preferably 100 mJ / cm ２ ~5000mJ / cm ２ The irradiation temperature may be, for example, from -20°C to 80°C, preferably from -20°C to 60°C.

[0080] In one embodiment, voltage is applied using a first electrode disposed on the first major surface side of the PDLC layer and a second electrode disposed on the second major surface side, and regions of different electric field strength are formed by controlling the separation distance between the first and second electrodes. Step C will now be described with reference to FIG. 5 . In the embodiment shown in FIG. 5 , step D is performed before step C, and a first transparent substrate 20 serving as a first substrate is disposed on the first major surface side of the PDLC layer 10 a, and a second transparent substrate 30 serving as a second substrate is disposed on the second major surface side. Unlike the illustrated example, the first and / or second major surfaces of the PDLC layer may be exposed.

[0081] FIG. 5( a) is a schematic cross-sectional view showing the PDLC layer obtained in step B in a state where no voltage is applied. The PDLC layer 10a includes a polymer matrix 12 and liquid crystal droplets 14' dispersed in the polymer matrix 12. The liquid crystal droplets 14' include a non-polymerizable liquid crystal compound 14a and a polymerizable liquid crystal compound 14c. A first electrode 40 is disposed on the outer side of the first transparent substrate 20 (the side opposite the side where the PDLC layer is disposed), and a second electrode 50 capable of transmitting active energy rays is disposed on the outer side of the second transparent substrate 30 (the side opposite the side where the PDLC layer is disposed). Since no voltage is applied to the electrodes 40 and 50 from a power source 60 and no electric field is generated between them, the non-polymerizable liquid crystal compound 14a and the polymerizable liquid crystal compound 14c in the liquid crystal droplets 14' are in a non-oriented state. Furthermore, the first electrode 40 is formed so that the surface height on the PDLC layer 10a side varies depending on the region, thereby forming regions with different inter-electrode distances.

[0082] The regions with different inter-electrode distances can be freely designed, for example, by changing the surface shape of the first electrode and / or second electrode on the PDLC layer side. Specifically, a desired inter-electrode distance can be achieved by providing any desired pattern of unevenness, steps, inclination, etc. on the surface of the first electrode and / or second electrode. For example, as shown in FIG. 6 , by providing tapered convex portions 42 on the surface of electrode 40a, the inter-electrode distance can be continuously changed, thereby continuously changing the in-plane orientation of the polymerizable liquid crystal compound and non-polymerizable liquid crystal compound in the liquid crystal droplets. In this case, by changing the height H and the tilt angle θ, the amount and rate of change in the inter-electrode distance can be controlled, resulting in the optical film having a haze gradient of any desired steepness or steepness. The height H and the tilt angle θ can each be set to any appropriate value depending on the haze pattern desired for the optical film.

[0083] FIG. 5B is a schematic diagram illustrating an embodiment in which the polymerizable liquid crystal compound 14c is polymerized by UV irradiation. UV irradiation is performed while a voltage is applied between the first electrode 40 and the second electrode 50 from a power source 60. The application of the voltage generates an electric field between the first electrode 40 and the second electrode 50, with the strength depending on the separation distance between them, resulting in multiple regions of different electric field strength. In each of these multiple regions, the non-polymerizable liquid crystal compound 14a and the polymerizable liquid crystal compound 14c in the liquid crystal droplet 14' are aligned according to the electric field strength. Specifically, in the region where the separation distance between the first electrode 40 and the second electrode 50 is smallest, the non-polymerizable liquid crystal compound 14a and the polymerizable liquid crystal compound 14c are aligned approximately perpendicular to the major surface of the PDLC layer 10a. As the separation distance increases, the degree of alignment weakens. By polymerizing the polymerizable liquid crystal compound 14c under these conditions, a diffusion layer 10 is formed, as shown in FIG. 5C, having multiple regions in which the liquid crystal polymer 14b in the dispersed particles 14 has different alignment states, as shown in FIG.

[0084] The voltage applied during polymerization is not limited as long as the polymerizable liquid crystal compound exhibits the desired alignment, and can be appropriately set depending on the haze desired for the optical film, the distance between the electrodes, etc. The voltage can be, for example, 10 V to 100 kV, and preferably 100 V to 10 kV.

[0085] B-4. Step D In step D, a second substrate is placed on the side (second main surface side) of the PDLC layer or the diffusion layer opposite to the side (first main surface side) on which the first substrate is provided. Any appropriate substrate may be used as the first substrate, and the second transparent substrate described in section A-4 may be preferably used. Step D may be performed before step C, i.e., before polymerizing the polymerizable liquid crystal compound, or after step C, i.e., after polymerizing the polymerizable liquid crystal compound.

[0086] According to the method for producing an optical film including step D, by using the first transparent substrate described in section A-3 and the second transparent substrate described in section A-4 as the first substrate and the second substrate, respectively, an optical film can be obtained that has the first transparent substrate and the second transparent substrate and a diffusion layer directly sandwiched therebetween.

[0087] From the viewpoint of obtaining sufficient adhesion, the second substrate is laminated on the second main surface side of the PDLC layer or the diffusion layer, preferably using a laminator, while applying a laminating pressure of 0.006 MPa / m to 7 MPa / m, more preferably 0.06 MPa / m to 0.7 MPa / m.

[0088] A method for producing an optical film according to a second embodiment of the present invention includes: (Step I) applying a coating liquid containing a polymer matrix-forming resin, a polymerizable liquid crystal compound, and a solvent to a first substrate to obtain a coating layer; (Step II) drying the coating layer to obtain a polymer-dispersed liquid crystal layer containing a polymer matrix and droplets containing the polymerizable liquid crystal compound dispersed in the polymer matrix; and (Step III) irradiating a predetermined region with active energy rays while applying a voltage to the polymer-dispersed liquid crystal layer to polymerize the polymerizable liquid crystal compound. The method for producing an optical film according to the second embodiment may further include, as necessary, (Step IV) disposing a second substrate on the side of the PDLC layer or the diffusion layer opposite the side on which the first substrate is provided, before or after polymerizing the polymerizable liquid crystal compound. According to the method for producing an optical film according to the second embodiment, the polymerizable liquid crystal compound is polymerized in an aligned state in the region irradiated with active energy rays, thereby producing a liquid crystal polymer with a fixed aligned state. On the other hand, in regions not irradiated with active energy rays, the polymerizable liquid crystal compound does not polymerize and remains in a non-oriented state when no voltage is applied. As a result, a diffusion layer is formed having multiple regions with different liquid crystal polymer content ratios, and the haze in regions with a higher liquid crystal polymer content (irradiated regions) is lower than the haze in regions with a lower content ratio (non-irradiated regions). The optical film manufacturing method according to the second embodiment can suitably produce an optical film described in Section A (e.g., the optical film of the second embodiment). Furthermore, the optical film manufacturing method according to the second embodiment can suitably produce an optical film in which the boundary between the irradiated and non-irradiated regions is clear and the haze contrast between these regions is high.

[0089] The same explanations as for step A, step B, and step D in the method for producing an optical film according to the first embodiment can be applied to step I, step II, and step IV, respectively, except that a photopolymerization initiator is used as the polymerization initiator.

[0090] In step III, while a voltage is applied to the PDLC layer, a predetermined region is irradiated with active energy rays to polymerize the polymerizable liquid crystal compound. Typically, the active energy rays are irradiated through a photomask having openings of a predetermined pattern.

[0091] Examples of active energy rays that can be used 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 light that travels in a straight line from the irradiation source. The ultraviolet irradiation conditions can be the same as those described in the method for producing an optical film according to the first embodiment.

[0092] 7 is a schematic diagram illustrating one embodiment of step III. In the embodiment shown in FIG. 7, step IV is performed before step III, and a first transparent substrate 20 serving as a first substrate is disposed on the first major surface side of the PDLC layer 10a, and a second transparent substrate 30 serving as a second substrate is disposed on the second major surface side. Unlike the illustrated example, the first major surface and / or the second major surface of the PDLC layer may be exposed.

[0093] The PDLC layer 10a includes a polymer matrix 12 and liquid crystal droplets 14' dispersed in the polymer matrix 12, and the liquid crystal droplets 14' include a non-polymerizable liquid crystal compound 14a and a polymerizable liquid crystal compound 14c. A first electrode 40 is disposed on the outer side of the first transparent substrate 20 (the side opposite to the side on which the PDLC layer is disposed), and a second electrode 50 that is transmissive to active energy rays is disposed on the outer side of the second transparent substrate 30 (the side opposite to the side on which the PDLC layer is disposed).

[0094] In Figure 7(a), a voltage is applied to the electrodes 40 and 50 from a power source 60, generating an electric field between them, causing the non-polymerizable liquid crystal compounds 14a and polymerizable liquid crystal compounds 14c in the liquid crystal droplets 14' to be aligned in a substantially vertical direction. Preferably, the alignment state of the non-polymerizable liquid crystal compounds 14a and polymerizable liquid crystal compounds 14c is uniform throughout the entire PDLC layer. In this state, the PDLC layer is irradiated with active energy rays (ultraviolet rays in the illustrated example) through a photomask 70 having openings in a predetermined pattern. This polymerizes the polymerizable liquid crystal compounds 14c in the irradiated areas, producing liquid crystal polymers 14b.

[0095] 7B, after irradiation with active energy rays, the irradiated area of ​​the diffusion layer 10 contains first dispersed particles 14 containing a non-polymerizable liquid crystal compound 14a and a liquid crystal polymer 14b, while the non-irradiated area contains second dispersed particles (liquid crystal droplets) 14' containing a non-polymerizable liquid crystal compound 14a and a polymerizable liquid crystal compound 14c. In the first dispersed particles 14, the liquid crystal polymer 14b has a fixed orientation, and the non-polymerizable liquid crystal compound 14a is oriented along the liquid crystal polymer 14b. In this embodiment, the irradiated area may exhibit lower haze than the non-irradiated area.

[0096] The voltage applied during polymerization is not limited as long as the polymerizable liquid crystal compound exhibits the desired alignment, and can be appropriately set depending on the haze desired for the optical film, the distance between the electrodes, etc. The voltage can be, for example, 10 V to 100 kV, and preferably 100 V to 10 kV.

[0097] If necessary, after step III, the non-irradiated region may be irradiated with active energy rays without applying a voltage. This allows the polymerizable liquid crystal compound contained in the non-irradiated region to be polymerized while remaining in a non-oriented state to produce a liquid crystal polymer. Alternatively, in step III, the polymerizable liquid crystal compound may be polymerized through a photomask without applying a voltage, and then the non-irradiated region may be irradiated with active energy rays while applying a voltage. That is, the method for producing an optical film according to the third embodiment of the present invention includes: (Step I) applying a coating liquid containing a polymer matrix-forming resin, a polymerizable liquid crystal compound, and a solvent to a first substrate to obtain a coating layer; (Step II) drying the coating layer to obtain a polymer-dispersed liquid crystal layer containing a polymer matrix and droplets containing the polymerizable liquid crystal compound dispersed in the polymer matrix; (Step IIIα) irradiating a predetermined region with active energy rays while no voltage is applied to the polymer-dispersed liquid crystal layer to polymerize the polymerizable liquid crystal compound; and (Step IIIβ) irradiating the remaining region with active energy rays while a voltage is applied to the polymer-dispersed liquid crystal layer to polymerize the polymerizable liquid crystal compound. The method for producing an optical film according to the third embodiment may further include (Step IV), as necessary, disposing a second substrate on the side of the PDLC layer or the diffusion layer opposite to the side where the first substrate is provided, before or after polymerizing the polymerizable liquid crystal compound. According to these methods, the optical film described in Section A (specifically, the optical film of the first embodiment) can be suitably obtained.

[0098] 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.

[0099] (1) Thickness: Measured using a digital micrometer (Anritsu Corporation, product name "KC-351C"). (2) Volume-average particle diameter of liquid crystal particles in liquid crystal emulsion: 0.1 wt % liquid crystal emulsion was added to 200 ml of an aqueous electrolyte solution (Coulter Corporation, "Isoton II"). The resulting mixture was used as a measurement sample using a Multisizer 3 (Coulter Corporation, aperture size = 20 μm). The volume of each particle diameter was measured by dividing the mixture into 256 equal logarithmic intervals from 0.4 μm to 12 μm, and the volume-average particle diameter was calculated by taking statistics of the volume for each particle diameter. Note that when particles of 12 μm or larger were present, the aperture size was changed to 30 μm, and the volume-average particle diameter was calculated by dividing the mixture into 256 equal logarithmic intervals from 0.6 μm to 18 μm. (3) Average particle diameter of resin particles: A measurement sample was prepared by adding a few drops of resin dispersion to 100 mL of water. A dynamic light scattering particle size distribution analyzer (Microtrac, Nanotrac 150) was used, and the measurement sample was placed in the measurement holder of the analyzer. After checking on the monitor of the analyzer that the concentration was measurable, the measurement was carried out. (4) Haze: Measurement was carried out in accordance with JIS K 7136 using a Nippon Denshoku product named NDH4000.

[0100] Example 1 (Preparation of emulsion coating liquid) 53.7 parts of a non-polymerizable liquid crystal compound (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 compound (manufactured by BASF Corporation, product name "PALIOCOLOR LC-242"), 0.1 parts of a photopolymerization initiator (manufactured by IGM, product name "OMNIRAD651"), 39.8 parts of pure water, and 0.5 parts of a dispersant (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., "Noigen ET159") were mixed and stirred with a homogenizer at 100 rpm for 10 minutes to prepare a liquid crystal emulsion. The average particle size of the liquid crystal particles in the resulting liquid crystal emulsion was 3.4 μm. 38.4 parts of the liquid crystal emulsion, 19.1 parts of a polyether-based polyurethane resin aqueous dispersion (manufactured by DSM, trade 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, Ltd., trade 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 Corporation, 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 were mixed to obtain an emulsion coating liquid (solid content concentration: 40 wt%).

[0101] (Application and Drying of Emulsion Coating Liquid) The emulsion coating liquid was applied to one side of a PET film (thickness: 125 μm) as a first transparent substrate to form a coating layer with a thickness of 20 μm. 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 a PDLC layer with a thickness of 8 μm.

[0102] (Lamination of second transparent substrate) A PET film (thickness 125 μm) was laminated on the PDLC layer as a second transparent substrate using a laminator while applying a lamination pressure of 0.4 MPa / m. This resulted in a laminate having a configuration of [first transparent substrate / PDLC layer / second transparent substrate]. The resulting laminate exhibited a uniform haze (haze: 90%) across the entire main surface.

[0103] (UV irradiation) A flat metal electrode having a recess of 2 mm in depth on its upper surface was used as the first electrode. The laminate was placed so that the first transparent substrate was in contact with the upper surface of the first electrode, and an ITO-coated glass substrate was placed on top of it as the second electrode so that the ITO surface was in contact with the second transparent substrate. Next, a high-voltage power supply was used to apply a voltage of 2 kV to these electrodes, while irradiating the electrodes with 10 mW / cm under a UV-LED lamp (manufactured by Hamamatsu Photonics, product name "C11924-101", peak wavelength 365 nm). ２ The film was then exposed to light at 25°C for 10 minutes. This polymerized the polymerizable liquid crystal compound, resulting in an optical film having a configuration of [first transparent substrate / diffusion layer / second transparent substrate]. The inter-electrode distance in the region (region I) corresponding to the recesses of the first electrode was approximately 2250 μm, and the electric field strength was 0.89 V / μm. The inter-electrode distance in the region (region II) corresponding to the portions other than the recesses of the first electrode was approximately 250 μm, and the electric field strength was 7.8 V / μm.

[0104] The haze of the obtained optical film was measured and found to be 90% in Region I and 8% in Region II. This indicates that the orientation state of the liquid crystal polymer and liquid crystal compound in the dispersed particles in Region I of the diffusion layer is different from the orientation state of the liquid crystal polymer and liquid crystal compound in the dispersed particles in Region II, and more specifically, that the degree of orientation of the liquid crystal polymer and liquid crystal compound in the dispersed particles in Region I is lower than the degree of orientation of these in Region II.

[0105] The optical film of the present invention is suitably used for various applications such as a diffusion film and a design film.

[0106] REFERENCE SIGNS LIST 100 Optical film 10 Diffusion layer 12 Polymer matrix 14 Dispersed particles 14' Liquid crystal droplets 14a Liquid crystal compound (non-polymerizable liquid crystal compound) 14b Liquid crystal polymer 14c Polymerizable liquid crystal compound 20 First transparent substrate 30 Second transparent substrate 40 First electrode 50 Second electrode 60 Power source

Claims

1. A diffusion layer including a polymer matrix and a liquid crystal polymer, which is a polymer of a polymerizable liquid crystal compound, dispersed in the polymer matrix, and optionally dispersed particles containing a liquid crystal compound; The optical film, wherein the diffusion layer has a plurality of regions having different orientation states of the liquid crystal polymer and / or different content ratios of the liquid crystal polymer.

2. The optical film of claim 1 , wherein the plurality of regions are arranged in a predetermined pattern.

3. The optical film according to claim 1 , wherein a maximum difference in haze between portions corresponding to the plurality of regions is 10% or more in a plan view.

4. The optical film of claim 1 or 2, wherein the dispersed particles comprise the liquid crystal polymer and the liquid crystal compound.

5. 5. The optical film according to claim 4, wherein a content ratio of the liquid crystal polymer to a total content of the liquid crystal polymer and the liquid crystal compound is 5% by weight or more.

6. 3. The optical film according to claim 1, wherein the total content of the liquid crystal polymer and, if present, the liquid crystal compound in the diffusion layer is 30% by weight to 70% by weight.

7. The optical film according to claim 1 , further comprising a first transparent substrate disposed on a first main surface side of the diffusion layer.

8. The optical film according to claim 7 , further comprising a second transparent substrate disposed on a second main surface side of the diffusion layer.

9. The optical film according to claim 1 or 2, which does not have an electrode layer.

10. A diffusion layer including a polymer matrix and dispersed particles including a liquid crystal polymer that is a polymer of a polymerizable liquid crystal compound and is dispersed in the polymer matrix, The optical film has, in a plan view, a plurality of regions that exhibit different hazes depending on the alignment state of the liquid crystal polymer.

11. A diffusion layer including a polymer matrix and dispersed particles dispersed in the polymer matrix, the diffusion layer has a region including dispersed particles including a polymerizable liquid crystal compound and a region including dispersed particles including a liquid crystal polymer that is a polymer of the polymerizable liquid crystal compound, In a plan view, these regions exhibit different hazes from each other.

12. applying a coating liquid containing a polymer matrix-forming resin, a polymerizable liquid crystal compound, and a solvent to a first substrate to obtain a coating layer; drying the coating layer to obtain a polymer dispersed liquid crystal layer including a polymer matrix and droplets including the polymerizable liquid crystal compound dispersed in the polymer matrix; and polymerizing the polymerizable liquid crystal compound while applying voltages from a first main surface side and a second main surface side of the polymer dispersed liquid crystal layer so as to generate regions having different electric field intensities; A method for producing an optical film, comprising:

13. the voltage application is performed using a first electrode disposed on the first principal surface side of the polymer dispersed liquid crystal layer and a second electrode disposed on the second principal surface side of the polymer dispersed liquid crystal layer; The method for producing an optical film according to claim 12 , further comprising controlling a distance between the first electrode and the second electrode so as to generate regions having different electric field strengths.

14. applying a coating liquid containing a polymer matrix-forming resin, a polymerizable liquid crystal compound, and a solvent to a first substrate to obtain a coating layer; drying the coating layer to obtain a polymer dispersed liquid crystal layer including a polymer matrix and droplets including the polymerizable liquid crystal compound dispersed in the polymer matrix; and applying an active energy ray to a predetermined region so as to form an irradiated region and a non-irradiated region while applying a voltage to the polymer dispersed liquid crystal layer, thereby polymerizing the polymerizable liquid crystal compound in the irradiated region; A method for producing an optical film, comprising:

15. The method for producing an optical film according to claim 12 , wherein the coating liquid is an emulsion containing liquid crystal particles containing the polymerizable liquid crystal compound as a dispersoid.

16. The method for producing an optical film according to claim 12 , wherein the coating liquid further contains a non-polymerizable liquid crystal compound.