Diffusion film and light diffusion device

Abstract

To provide a diffusion film with which light distribution is controlled.SOLUTION: Provided is a diffusion film including a diffusion layer that includes a polymer matrix and a dispersion particle dispersed in the polymer matrix and including a liquid crystal polymer, which is a polymer of a polymerizable liquid crystal component, and a non-polymerizable liquid crystal component as a discretionary component. The diffusion layer has a A1 region indicating a maximum rectilinear transmitted light intensity at an incident angle θ° (however, θ>0) and a B1 region indicating a maximum rectilinear transmitted light intensity at an incident angle 0°, and the orientation state and / or content ratio of the liquid crystal polymer included in the dispersion particle are mutually different in the A1 region and the B1 region.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a diffusion film and a light diffusion device. [Background technology]

[0002] A polymer dispersed liquid crystal (hereinafter sometimes referred to as "PDLC") layer, which contains a polymer matrix and droplets of a liquid crystal component (hereinafter sometimes referred to as "liquid crystal droplets") dispersed therein, can cause light scattering as the liquid crystal droplets act as scattering particles due to the difference in refractive index between the polymer matrix and the liquid crystal component.

[0003] By utilizing the light scattering effect, the PDLC film can be used as a diffusion film. For example, Patent Document 1 proposes using the PDLC film as a diffusion film for a direct backlight. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-008005 A Summary of the Invention [Problem to be solved by the invention]

[0005] There are cases where a diffusion film is required to have a specific light distribution pattern, but in the case of a diffusion film using the above-mentioned PDLC layer, it is difficult to control the light distribution.

[0006] SUMMARY OF THE PRESENT EMBODIMENTS The present invention has a primary object to provide a diffusion film with controlled light distribution, and a further object to provide a diffusion film with patterned light distribution. [Means for solving the problem]

[0007] [1] According to one aspect of the present invention, there is provided a diffusion film comprising a diffusion layer including a polymer matrix and dispersed particles dispersed in the polymer matrix, the dispersed particles including a liquid crystal polymer which is a polymer of a polymerizable liquid crystal component and an optional non-polymerizable liquid crystal component, wherein the diffusion layer has an A1 region which exhibits a maximum straight-transmitted light intensity at an incident angle of θ° (where θ>0) and a B1 region which exhibits a maximum straight-transmitted light intensity at an incident angle of 0°, and the orientation state and / or content ratio of the liquid crystal polymer contained in the dispersed particles are different from each other in the A1 region and the B1 region. [2] The diffusion film according to [1] above may contain the liquid crystal polymer in which the dispersed particles are oriented in a predetermined direction in the A1 region. [3] In the diffusion film described in [2], the predetermined direction may be a thickness direction or a direction perpendicular to the thickness direction. [4] The diffusion film according to any one of [1] to [3] above, wherein the average ordinary refractive index of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component is no a , the average extraordinary refractive index is ne a When the refractive index of the polymer matrix is ​​np, no a <np<ne a The following relationship may be satisfied. [5] The diffusion film described in [4] above has a np-no a and / or 0.01≦ne a The -np relationship may be satisfied. [6] In the diffusion film described in any one of [1] to [5] above, the content of the liquid crystal polymer in the A1 region relative to the total content of the liquid crystal polymer and the non-polymerizable liquid crystal component may be 5% by weight or more. [7] According to another aspect of the present invention, there is provided a method for producing a liquid crystal display comprising the steps of: (a) providing a liquid crystal display having a liquid crystal composition that is a liquid crystal composition having a refractive index of 100 nm or less; and (b) providing a liquid crystal composition having a refractive index of 100 nm or less; a , the average extraordinary refractive index is ne aWhen the refractive index of the polymer matrix is ​​np, no a <np<ne a A diffusion film is provided that satisfies the relationship: [8] In the diffusion film described in [7] above, the diffusion layer may have a region containing the liquid crystal polymer in which the dispersed particles are oriented in a predetermined direction and the non-polymerizable liquid crystal component as an optional component. [9] In the diffusion film according to [8] above, the predetermined direction may be a thickness direction or a direction perpendicular to the thickness direction.

[10] The diffusion film according to any one of [1] to [9] above may further include a supporting substrate disposed on one or both sides of the diffusion layer.

[11] According to another aspect of the present invention, there is provided a light diffusion device comprising a light source unit and the diffusion film according to any one of [1] to

[10] above.

[12] In the light diffusing device described in

[11] above, the light source section may include a plurality of point light sources. Effect of the Invention

[0008] According to the present invention, a diffusion film having an area exhibiting a light distribution characteristic in which the straight-through transmitted light intensity of light incident from an oblique direction is higher than the straight-through transmitted light intensity of light incident from a front direction can be provided. The diffusion film can further have an area exhibiting a light distribution characteristic in which the straight-through transmitted light intensity of light incident from a front direction is higher than the straight-through transmitted light intensity of light incident from an oblique direction. Furthermore, these areas can be formed in a desired pattern. [Brief description of the drawings]

[0009] [Figure 1A] FIG. 1A is a schematic top view of an example of a diffusion film according to an embodiment of the present invention. [Figure 1B] FIG. 1B is a schematic cross-sectional view illustrating the configuration of the diffusion film shown in FIG. 1A. [Diagram 2] FIG. 2 is a schematic diagram illustrating the light distribution of the diffusion film shown in FIGS. 1A and 1B. [Diagram 3]3(a) and (b) are schematic diagrams illustrating step III of an example of a method for producing a diffusion film. [Figure 4] FIG. 4 is a schematic cross-sectional view illustrating the configuration of another example of the diffusion film according to an embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic cross-sectional view illustrating the configuration of another example of the diffusion film according to an embodiment of the present invention. [Figure 6] FIG. 6 is a schematic cross-sectional view showing the configuration of a light diffusing device according to one embodiment of the present invention. [Figure 7] FIG. 7 is a graph showing the results of measuring the light distribution of a diffusion film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments. In addition, each embodiment can be appropriately combined. In this specification, "~" representing a numerical range includes the upper and lower limit numerical values. In order to make the explanation clearer, the drawings may be schematic in terms of the width, thickness, shape, etc. of each part compared to the embodiment, but it is merely an example and does not limit the interpretation of the present invention.

[0011] A. Diffusion film 1A and 1B are a schematic top view and a schematic cross-sectional view, respectively, illustrating the configuration of an example of a diffusion film according to an embodiment of the present invention. FIG. 2 is a schematic view illustrating the light distribution of the diffusion film shown in FIG.

[0012] The diffusion film 100A shown in FIGS. 1A and 1B includes a diffusion layer 110, a first support substrate 120 disposed on one side of the diffusion layer 110, and a second support substrate 130 disposed on the other side. The diffusion layer 110 has an A1 region including a polymer matrix 10 and dispersed particles 20 including a liquid crystal polymer 22, which is a polymer of a polymerizable liquid crystal component, and a non-polymerizable liquid crystal component 26, and a B1 region including a polymer matrix 10 and dispersed particles 20 including a polymerizable liquid crystal component 24 and a non-polymerizable liquid crystal component 26, which are dispersed in the polymer matrix 10. Here, the liquid crystal polymer 22 is a polymer of a polymerizable liquid crystal component and is non-liquid crystal. That is, in the liquid crystal polymer 22, for example, transition to a liquid crystal phase, a glass phase, or a crystalline phase due to a temperature change specific to a liquid crystal compound does not occur. In addition, the non-polymerizable liquid crystal component 26 is an optional component, and the dispersed particles 20 do not need to include the non-polymerizable liquid crystal component 26.

[0013] As shown in FIGS. 1A and 1B, in the A1 region, the dispersed particles 20 contain a liquid crystal polymer 22 oriented in a predetermined direction (thickness direction in the illustrated example). On the other hand, in the B1 region, the dispersed particles 20 contain a polymerizable liquid crystal component 24 in a non-oriented state. The content of the liquid crystal polymer 22 in the B1 region is less than the content of the liquid crystal polymer 22 in the A1 region. For example, the dispersed particles 20 in the B1 region may not substantially contain the liquid crystal polymer 22. In addition, in the A1 region, the non-polymerizable liquid crystal component 26 in the dispersed particles 20 is oriented along the orientation of the liquid crystal polymer 22, and in the B1 region, the non-polymerizable liquid crystal component 26 in the dispersed particles 20 exists in a non-oriented state similar to the polymerizable liquid crystal component 24. In this specification, with regard to a compound such as a liquid crystal polymer or a liquid crystal component, the "non-oriented state" refers to a state in which the molecules of the compound are not aligned with a certain regularity. Furthermore, with respect to a diffusion layer or diffusion film, the "thickness direction" may include a direction that forms an angle of, for example, 90°±2° or, for example, 90°±3° with respect to the principal surface thereof.

[0014] As will be described below, the polymerizable liquid crystal component 24, the non-polymerizable liquid crystal component 26, and the polymer matrix 10 typically satisfy the relationship of no a <np<ne a (where no a is the average ordinary light refractive index of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component, ne a is the average extraordinary light refractive index of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component, and np is the refractive index of the polymer matrix). The liquid crystal polymer 22 is a polymer of the polymerizable liquid crystal component 24 and exhibits refractive index characteristics similar to those of the polymerizable liquid crystal component 24. Therefore, in the A1 region of the diffusion layer 110, the incident light from the front direction is scattered due to the difference between the refractive index of the polymer matrix 10 and the refractive index of the dispersed particles 20 (specifically, the difference between no a and np or the difference between ne a and np). On the other hand, the light incident at an angle where the difference between the refractive index of the polymer matrix 10 and the refractive index of the dispersed particles 20 is small can be suppressed from scattering and can exhibit a higher straight-through transmission intensity than the straight-through transmission light intensity of the incident light with an incident angle of 0°. Therefore, as shown in FIG. 2, the diffusion film 100A (more specifically, the diffusion layer 110) exhibits the maximum straight-through transmission light intensity for the light incident at a predetermined incident angle θ° (where θ>0) in the A1 region, and the straight-through transmission light intensity of the light incident from the front direction (incident angle 0°) is smaller than that. On the other hand, in the B1 region, since the dispersed particles 10 contain the non-aligned polymerizable liquid crystal component 24 and the non-polymerizable liquid crystal component 26, the incident light can be uniformly dispersed. Therefore, the straight-through transmission intensity decreases according to the optical path length, and the straight-through transmission light intensity of the light incident from the front direction becomes the highest. Conventional PDLC layers are generally fabricated using a liquid crystal component and a polymer matrix that satisfy the relationship of np≒no<ne and do not realize light distribution such as in the A1 region. The angle θ can be adjusted according to the purpose and is, for example, 10° to 80°, 15° or more and less than 45° or 20° to 40°, or more than 45° and 75° or less or 50° to 70°. The light distribution can be controlled by adjusting the angle θ by changing the difference between the refractive index of the polymer matrix and the refractive index of the liquid crystal component, etc.

[0015] The haze of the region of the diffusion film corresponding to the A1 region of the diffusion layer in plan view (hereinafter, sometimes referred to as the A1 region of the diffusion film) and the haze of the region of the diffusion film corresponding to the B1 region of the diffusion layer (hereinafter, sometimes referred to as the B1 region of the diffusion film) can be appropriately set according to the purpose. The haze of the A1 region of the diffusion film can be, for example, 30.0% to 99.9%, and may be 40.0% to 70.0%, or 60.0% to 90.0%. The haze of the B1 region of the diffusion film can be, for example, 20.0% to 99.9%, and may be 30.0% to 70.0%, or 60.0% to 99.9%.

[0016] The total light transmittance of the A1 region of the diffusion film and the total light transmittance of the B1 region can be appropriately set according to the purpose. The total light transmittance of the A1 region of the diffusion film can be, for example, 40% to 95%, and may be 60% to 80% or 70% to 90%. The total light transmittance of the B1 region of the diffusion film can be, for example, 40% to 95%, and may be 60% to 80%, or 70% to 90%. The total light transmittance can be measured, for example, according to JIS K 7361.

[0017] When the incident angle showing the maximum straight transmitted light intensity in the A1 region of the diffusion film is θ°, the ratio of the straight transmitted light intensity at an incident angle of 0° to the straight transmitted light intensity at an incident angle of θ° can be set appropriately depending on the purpose, and may be, for example, 0.05 to 0.9, 0.2 to 0.9, or 0.1 to 0.4.

[0018] The thickness of the diffusion film is, for example, 30 μm to 250 μm, preferably 40 μm to 150 μm, and more preferably 50 μm to 120 μm.

[0019] The shapes and arrangement patterns of the A1 and B1 regions can be appropriately set according to the purpose. For example, the A1 and B1 regions may each have any shape (circular, elliptical, rectangular, polygonal, etc.). For example, the A1 region may be arranged so as to surround the outside of the B1 region, or the B1 region may be arranged so as to surround the outside of the A1 region.

[0020] <Diffusion layer> 1B has an A1 region including a polymer matrix 10 and dispersed particles 20 that are dispersed in the polymer matrix 10 and include a liquid crystal polymer 22 that is a polymer of a polymerizable liquid crystal component and a non-polymerizable liquid crystal component 26, and a B1 region including a polymer matrix 10 and dispersed particles 20 that are dispersed in the polymer matrix 10 and include a polymerizable liquid crystal component 24 and a non-polymerizable liquid crystal component 26. As described above, the non-polymerizable liquid crystal component is an optional component, but by further including the non-polymerizable liquid crystal component in the dispersed particles, the alignment control of the liquid crystal polymer and the polymerizable liquid crystal component can be more suitably performed.

[0021] The polymer matrix may be composed of any suitable resin. The resin for forming the polymer matrix may be appropriately selected depending on the light transmittance, the refractive index of the polymerizable liquid crystal component or the non-polymerizable liquid crystal component, the adhesion to the support substrate, and the like. For example, water-soluble or water-dispersible resins such as urethane-based resins, polyvinyl alcohol-based resins, polyethylene-based resins, polypropylene-based resins, and acrylic-based resins may be preferably used. The resin for forming the polymer matrix may be used alone or in combination.

[0022] The refractive index of the polymer matrix is, for example, 1.50 to 1.75, preferably 1.525 to 1.725, and more preferably 1.55 to 1.70.

[0023] 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 in both the A1 and B1 regions. If the content of the polymer matrix is ​​within this range, it is possible to obtain effects such as good mechanical strength and prevention of liquid crystal leakage from the edges.

[0024] As described above, the liquid crystal polymer contained in the A1 region is a polymer of a polymerizable liquid crystal component. The polymerizable liquid crystal component constituting the liquid crystal polymer is the same liquid crystal component as the polymerizable liquid crystal component contained in the B1 region.

[0025] In the dispersed particles in the A1 region, the liquid crystal polymer is typically oriented in a predetermined direction, preferably, for example, the thickness direction of the diffusion layer and a direction parallel to the thickness direction.

[0026] As the polymerizable liquid crystal component, any polymerizable liquid crystal compound can be used alone or in combination of two or more depending on the birefringence, compatibility with the non-polymerizable liquid crystal component, etc. 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.

[0027] The dielectric anisotropy of the polymerizable liquid crystal component may be positive or negative. The polymerizable liquid crystal component may contain a crosslinked liquid crystal compound having two or more functionalities. As the polymerizable liquid crystal component, for example, polymerizable mesogen compounds described in JP-A-2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445, etc., can be used. As the polymerizable liquid crystal component, for example, a nematic liquid crystal monomer is preferable.

[0028] As the non-polymerizable liquid crystal component, any non-polymerizable liquid crystal compound can be used alone or in combination of two or more depending on the birefringence, compatibility with the polymerizable liquid crystal component, etc. The dielectric anisotropy of the non-polymerizable liquid crystal component can be positive or negative. The non-polymerizable liquid crystal component can be, for example, a nematic type, a smectic type, or a cholesteric type liquid crystal component. It is preferable to use a nematic type liquid crystal component because it can achieve high linear transmission light intensity in the aligned state.

[0029] 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 liquid crystal compounds may be used alone or in combination.

[0030] Typically, the polymerizable liquid crystal component, the non-polymerizable liquid crystal component, and the polymer matrix are a <np<ne a Here, no a is the average ordinary refractive index of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component, and ne a is the average extraordinary refractive index of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component, and np is the refractive index of the polymer matrix. The average ordinary refractive index and the average extraordinary refractive index are each calculated as a weighted average taking into account the blending ratio of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component. If the dispersed particles do not contain a non-polymerizable liquid crystal component, no a corresponds to the ordinary refractive index of the polymerizable liquid crystal component, and ne a corresponds to the extraordinary refractive index of the polymerizable liquid crystal component. When the polymerizable liquid crystal component, the non-polymerizable liquid crystal component, and the polymer matrix satisfy the above relationship, a diffusion layer having a region where the incident light from an oblique direction exhibits the maximum straight-transmitted light intensity can be suitably obtained.

[0031] In one embodiment, the polymerizable liquid crystal component, the non-polymerizable liquid crystal component, and the polymer matrix preferably have a molecular weight of 0.01≦np-no a More preferably, 0.01≦np-no a ≦0.25, more preferably 0.02≦np-no a ≦0.25 (e.g. 0.03≦np-no a ≦0.25, 0.04≦np-no a ≦0.25, or 0.05≦np-no aIn one embodiment, the polymerizable liquid crystal component, the non-polymerizable liquid crystal component, and the polymer matrix preferably satisfy the relationship of 0.01≦ne≦0.20. a -np relationship, more preferably 0.01≦ne a -np≦0.35, more preferably 0.02≦ne a -np≦0.35 (e.g. 0.03≦ne a - np ≤ 0.35, 0.04 ≤ ne a - np ≤ 0.35, or 0.05 ≤ ne a -np≦0.30) is satisfied. When the polymerizable liquid crystal component, the non-polymerizable liquid crystal component, and the polymer matrix satisfy the above relationship, it is possible to sufficiently increase the difference between the rectilinear transmission light intensity of light incident from an oblique direction and the rectilinear transmission light intensity of light incident from the front direction.

[0032] The birefringence Δn (=ne−no) of the polymerizable liquid crystal component at a wavelength of 589 nm is preferably 0.05 to 0.35, and more preferably 0.1 to 0.3.

[0033] The birefringence Δn of the non-polymerizable liquid crystal component at a wavelength of 589 nm is preferably 0.05 to 0.35, and more preferably 0.1 to 0.3.

[0034] The total content ratio of the liquid crystal polymer and the non-polymerizable liquid crystal component in the A1 region (the content ratio of the liquid crystal polymer when the dispersed particles do not contain the non-polymerizable liquid crystal component) is, for example, 30% by weight to 70% by weight, preferably 35% by weight to 65% by weight, more preferably 40% by weight to 60% by weight. The content ratio of the liquid crystal polymer to the total content of the liquid crystal polymer and the non-polymerizable liquid crystal component in the A1 region may be, 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, more preferably 50% by weight or less. The total content ratio of the polymer matrix, the liquid crystal polymer, and the non-polymerizable liquid crystal component in the A1 region may be, for example, 80% by weight or more, preferably 90% by weight to 99.9% by weight, and preferably 95% by weight to 99.9% by weight.

[0035] The total content ratio of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component in the B1 region (the content ratio of the polymerizable liquid crystal component when the dispersed particles do not contain the non-polymerizable liquid crystal component) is, 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. The content ratio of the polymerizable liquid crystal component to the total content of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component in the B1 region is, for example, 5% by weight or more, preferably 7% by weight or more, and 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 ratio of the polymer matrix, the polymerizable liquid crystal component, and the non-polymerizable liquid crystal component in the B1 region may be, for example, 80% by weight or more, preferably 90% by weight to 99.9% by weight, and preferably 95% by weight to 99.9% by weight.

[0036] The diffusion layer may further contain any appropriate additives as necessary. Examples of such additives include a polymerization initiator, a dispersant, a leveling agent, a crosslinking agent, and a dispersion stabilizer. The total content of the additives in the diffusion layer may be, for example, 20% by weight or less, preferably 0.1% by weight to 10% by weight, and more preferably 0.1% by weight to 5% by weight.

[0037] The average particle diameter of the dispersed particles may be, for example, 0.2 μm to 15 μm, preferably 0.3 μm to 12 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 that the light passes through the dispersed particles without being scattered, and as a result, a problem may occur in which sufficient haze cannot be obtained. If the average particle diameter is too large, the dispersed particle size is too large than the wavelength of light, so that a problem may occur in which sufficient haze cannot be obtained. 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 diffusion layer.

[0038] The thickness of the diffusion layer is, for example, 3 μm to 60 μm, preferably 5 μm to 55 μm, and more preferably 8 μm to 50 μm.

[0039] <Supporting base material> The first supporting substrate and the second supporting substrate (hereinafter, sometimes collectively referred to as "supporting substrate") each include a substrate body. The supporting substrate may have a functional layer on one or both sides of the substrate body as necessary. Examples of the functional layer include a hard coat (HC) layer, a refractive index adjustment layer, a transparent electrode layer, and the like. The first supporting substrate and the second supporting substrate may have the same configuration (material and thickness of the substrate body, presence or absence or type of a functional layer, etc.) or may have different configurations. One or both of the first supporting substrate and the second supporting substrate may be omitted depending on the purpose, etc.

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

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

[0042] The substrate body 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 by rolls to greatly improve productivity.

[0043] The substrate body is typically a polymer film mainly composed of a thermoplastic resin. Examples of thermoplastic resins include polyester resins; cycloolefin resins such as polynorbornene; acrylic resins; polycarbonate resins; and cellulose resins. Among them, polyester resins, cycloolefin resins, and acrylic resins are preferred. These resins are excellent in transparency, mechanical strength, thermal stability, and moisture shielding properties. The above-mentioned thermoplastic resins may be used alone or in combination of two or more. In addition, optical films such as those 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 substrate body.

[0044] The thickness of the substrate body is preferably 200 μm or less, more preferably 3 μm to 100 μm, and further preferably 5 μm to 70 μm.

[0045] The hard coat layer, the refractive index adjustment layer, and the transparent electrode layer may have a configuration well known in the art, and therefore the detailed configurations thereof will not be described. The transparent electrode layer can be suitably used when aligning and polymerizing the polymerizable liquid crystal component.

[0046] The thickness of the supporting substrate is preferably 200 μm or less, more preferably 3 μm to 100 μm, and further preferably 5 μm to 70 μm.

[0047] <How to make the diffusion film> The diffusion film can be made in any suitable manner. In one embodiment, the method for producing the diffusion film includes the steps of: (Step I) applying a coating liquid containing a solvent, a polymer matrix-forming resin, a polymerizable liquid crystal component, and an optional non-polymerizable liquid crystal component to a first substrate to obtain a coating layer; (Step II) drying the coating layer to obtain a polymer dispersed liquid crystal (PDLC) layer including a polymer matrix and liquid crystal droplets including the polymerizable liquid crystal component and the non-polymerizable liquid crystal component dispersed in the polymer matrix; and (Step III) applying a voltage to the PDLC layer, and irradiating a predetermined region with active energy rays to polymerize the polymerizable liquid crystal component; Includes. Step III can provide a diffusion layer containing a polymer matrix and dispersed particles dispersed in the polymer matrix, the dispersed particles containing a liquid crystal polymer that is a polymer of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component as an optional component. The method for producing the above-mentioned diffusion film may, if necessary, further include, before or after step III, placing a second substrate on the side of the PDLC layer or diffusion layer opposite to the side on which the first substrate is provided (step IV). According to the manufacturing method of the diffusion film, the polymerizable liquid crystal component is polymerized in a state where it is aligned in a predetermined direction in the irradiated area irradiated with the active energy rays, and thus a liquid crystal polymer with a fixed alignment state is produced. On the other hand, in the non-irradiated area not irradiated with the active energy rays, the polymerizable liquid crystal component is not polymerized and is in a non-aligned state in the absence of applied voltage. As a result, the obtained diffusion layer has an irradiated area containing a liquid crystal polymer in which the dispersed particles are aligned in a predetermined direction, and a non-irradiated area containing a polymerizable liquid crystal component in which the dispersed particles are in a non-aligned state, the irradiated area being the A1 area, and the non-irradiated area being the B1 area.

[0048] (Process I) In step I, a coating liquid containing a solvent, a polymer matrix-forming resin, a polymerizable liquid crystal component, and an optional non-polymerizable liquid crystal component is applied to a first substrate to obtain a coating layer.

[0049] The coating liquid is preferably an emulsion containing liquid crystal particles containing a polymerizable liquid crystal component and optionally a non-polymerizable liquid crystal component as a dispersoid (hereinafter, may be referred to as "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 component and optionally a non-polymerizable liquid crystal component are dispersed in a solvent. The emulsion coating liquid preferably further contains a polymerization initiator, and may further contain any appropriate additive depending on the purpose.

[0050] As the solvent, water or a mixed solvent of water and a water-miscible organic solvent can be preferably used. As the water-miscible organic solvent, C1-3 alcohol, acetone, DMSO, etc. can be mentioned. The polymerizable liquid crystal component, the non-polymerizable liquid crystal component, and the resin for forming the polymer matrix are as described above. As the optional additive, a dispersant, a leveling agent, a crosslinking agent, etc. can be mentioned.

[0051] The content of the liquid crystal component in the solid content of the coating liquid (the total content of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component, if present) can be, for example, 30% by weight to 70% by weight, preferably 35% by weight to 65% by weight, and more preferably 40% by weight to 60% by weight.

[0052] The weight ratio of the polymerizable liquid crystal component to the non-polymerizable liquid crystal component in the coating liquid (polymerizable liquid crystal component:non-polymerizable liquid crystal component) may be, for example, 5:95 to 100:0, preferably 7:93 to 80:20, and more preferably 10:90 to 50:50.

[0053] The content of the polymer matrix-forming resin in the solid content of the coating liquid can be, for example, 30% by weight to 70% by weight, preferably 35% by weight to 65% by weight, and more preferably 40% by weight to 60% by weight.

[0054] The weight ratio of the content of the liquid crystal component in the coating liquid (the total content of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component if present) to the content of the polymer matrix forming resin (liquid crystal component:polymer matrix forming resin) can be, for example, 30:70 to 70:30, preferably 35:65 to 65:35, and more preferably 40:60 to 60:40. The total content of the polymer matrix forming resin and the liquid crystal component in the solid content of the coating liquid can be, for example, 80% by weight or more, preferably 90% by weight to 99.9% by weight, and more preferably 95% by weight to 99.9% by weight.

[0055] The average particle diameter of the liquid crystal particles is preferably 0.3 μm or more, more preferably 0.4 μm or more. The average particle diameter of the liquid crystal particles is preferably 15 μm or less, more preferably 12 μm or less. If the average particle diameter of the liquid crystal particles is within this range, the average particle diameter of the dispersed particles in the diffusion layer can be set to a desired range. The average particle diameter of the liquid crystal particles is a volume average particle diameter.

[0056] 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, more preferably 0.30 or less. In one embodiment, an emulsion coating liquid that is substantially free of liquid crystal particles having a particle size of less than 0.3 μm or more than 15 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 15 μm to the total volume of liquid crystal particles is 10% or less) may be used.

[0057] The average particle diameter of the resin particles for forming a polymer matrix is ​​preferably 10 nm to 500 nm, more preferably 30 nm to 400 nm, and further preferably 50 nm to 300 nm. Two or more kinds of resin particles having different resin types and / or average particle diameters may be used. The average particle diameter of the resin particles for forming a polymer matrix means the volume average median diameter, and can be measured using a dynamic light scattering particle size distribution measuring device.

[0058] As the polymerization initiator, any appropriate polymerization initiator can be used depending on the purpose. The polymerization initiator is preferably a photopolymerization initiator. Specific examples of photopolymerization initiators include 2,2-dimethoxy-2-phenylacetophenone, acetophenone, benzophenone, xanthone, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, benzoin propyl ether, benzyl 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, and more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polymerizable liquid crystal component.

[0059] Examples of the dispersant include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. The content of the dispersant is preferably 1 to 15 parts by weight, more preferably 2 to 10 parts by weight, based on 100 parts by weight of the solid content of the coating liquid.

[0060] Examples of the leveling agent include an acrylic leveling agent, a fluorine-based leveling agent, a silicone-based leveling agent, etc. The content of the leveling agent is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, relative to 100 parts by weight of the solid content of the coating liquid.

[0061] Examples of the crosslinking agent include aziridine-based crosslinking agents, isocyanate-based crosslinking agents, etc. The content of the crosslinking agent is preferably 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight, relative to 100 parts by weight of the solid content of the coating liquid.

[0062] The emulsion coating liquid 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 containing a liquid crystal component and a polymerization initiator, and any additives (for example, a dispersant, a leveling agent, a crosslinking agent). If necessary, a solvent may be further added during mixing. Alternatively, the emulsion coating liquid can be prepared by adding the liquid crystal component, the resin for forming a polymer matrix, the polymerization initiator, and any additives to a solvent and mechanically dispersing them.

[0063] The resin emulsion and the liquid crystal emulsion can be prepared, for example, by mechanical emulsification, microchannel method, membrane emulsification, etc. Among them, the liquid crystal emulsion is preferably prepared by the membrane emulsification method. According to the membrane emulsification method, an emulsion having a uniform particle size distribution can be suitably obtained. For details of the membrane emulsification method, the disclosures of JP-A-4-355719, JP-A-2015-40994, etc. (these are incorporated herein by reference) can be referred to.

[0064] The solids concentration of the coating liquid may be, for example, 20% by weight to 60% by weight, and preferably 30% by weight to 50% by weight.

[0065] The viscosity of the coating liquid can be appropriately adjusted so that the coating on the first substrate is performed suitably. The viscosity of the coating liquid during coating is preferably 20 mPas to 400 mPas, more preferably 30 mPas to 300 mPas, and even more preferably 40 mPas to 200 mPas. If the viscosity is less than 20 mPas, convection of the solvent becomes significant when the solvent is dried, and the thickness of the PDLC layer (as a result, the diffusion layer) may become unstable. If the viscosity exceeds 400 mPas, the bead of the coating liquid may become unstable. The viscosity of the coating liquid can be measured, for example, by a rheometer MCR302 manufactured by Anton Paar. The viscosity used here is the shear viscosity value under the conditions of 20°C and a shear rate of 1000 (1 / s).

[0066] Any suitable substrate may be used as the first substrate. By using the first supporting substrate as the first substrate, a diffusion film having the first supporting substrate and the diffusion layer may be suitably obtained. Depending on the purpose, the first substrate may be peeled off from the diffusion layer after the end of step III.

[0067] Any appropriate method can be adopted as the coating method. For example, roll coating method, spin coating method, wire bar coating method, dip coating method, die coating method, curtain coating method, spray coating method, knife coating method (comma coating method, etc.), etc. can be mentioned. Among them, roll coating method is preferable. For example, for coating by the roll coating method using a slot die, the description of JP2019-5698A can be referred to.

[0068] The thickness of the coating layer is preferably 3 μm to 100 μm, more preferably 4 μm to 80 μm, and further preferably 5 μm to 50 μm. Within such a range, a PDLC layer (and consequently a diffusion layer) with excellent thickness uniformity can be obtained.

[0069] (Process II) In step II, the coating layer is dried to obtain a PDLC layer containing a polymer matrix and liquid crystal droplets containing a polymerizable liquid crystal component and a non-polymerizable liquid crystal component dispersed in the polymer matrix. The solvent is removed from the coating layer by drying, forming a PDLC layer having a structure in which liquid crystal droplets are dispersed in a polymer matrix.

[0070] 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.

[0071] The drying temperature is preferably 20° C. to 150° C., and more preferably 25° C. to 80° C. The drying time is preferably 1 minute to 100 minutes, and more preferably 2 minutes to 10 minutes.

[0072] (Process III) In step III, active energy rays are irradiated to a predetermined region while a voltage is applied to the PDLC layer to polymerize the polymerizable liquid crystal component. Step III can provide a diffusion layer that includes a polymer matrix and dispersed particles that are dispersed in the polymer matrix and include a liquid crystal polymer that is a polymer of the polymerizable liquid crystal component and a non-polymerizable liquid crystal component as an optional component. The active energy rays can be irradiated through a photomask having openings of a predetermined pattern, for example.

[0073] Examples of the active energy rays include ultraviolet rays, infrared rays, X-rays, α rays, β rays, γ rays, and electron beams. Among these, ultraviolet rays are preferred. Moreover, the active energy rays are preferably collimated light that has a high linearity from the irradiation source.

[0074] The ultraviolet irradiation conditions can be appropriately set depending on the type of polymerizable liquid crystal component, the transmittance of the base material, 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 / cm2 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, and preferably from -20°C to 60°C.

[0075] 3(a) and (b) are schematic diagrams illustrating one embodiment of step III. In the embodiment shown in FIG. 3(a) and (b), step IV is performed before step III, and a first support substrate 120 as a first substrate is disposed on one side of the PDLC layer 110a, and a second support substrate 130 as a second substrate is disposed on the other side. Unlike the illustrated example, at least one surface of the PDLC layer may be exposed.

[0076] The PDLC layer 110a includes a polymer matrix 10 and liquid crystal droplets 20a dispersed in the polymer matrix 10, and the liquid crystal droplets 20a include a polymerizable liquid crystal component 24 and a non-polymerizable liquid crystal component 26. A first electrode 210 is disposed on the outer side of the first supporting substrate 120 (the side opposite to the side on which the PDLC layer is disposed), and a second electrode 220 capable of transmitting active energy rays is disposed on the outer side of the second supporting substrate 130 (the side opposite to the side on which the PDLC layer is disposed).

[0077] In FIG. 3(a), a voltage is applied to the electrodes 210 and 220 from a power source 230, and an electric field is generated between them. Therefore, the polymerizable liquid crystal component 24 and the non-polymerizable liquid crystal component 26 in the liquid crystal droplet 20a are aligned in the thickness direction. Preferably, the alignment state of the polymerizable liquid crystal component 24 and the non-polymerizable liquid crystal component 26 is uniform throughout the entire PDLC layer. In this state, active energy rays (ultraviolet rays in the illustrated example) are irradiated through a photomask 240 having openings in a predetermined pattern. As a result, the polymerizable liquid crystal component 24 in the irradiated area is polymerized to generate a liquid crystal polymer 22.

[0078] 3(b), after irradiation with active energy rays, the dispersed particles 20 in the diffusion layer 110 contain a liquid crystal polymer 22 and a non-polymerizable liquid crystal component 26 aligned in the thickness direction in the irradiated region, and contain a polymerizable liquid crystal component 24 and a non-polymerizable liquid crystal component 26 in a non-oriented state in the non-irradiated region. Therefore, the irradiated region can correspond to the A1 region where light incident at a predetermined incident angle θ° (where θ>0) exhibits the maximum straight-transmitted light intensity, and the non-irradiated region can correspond to the B1 region where light incident from the front direction exhibits the maximum straight-transmitted light intensity.

[0079] The voltage applied during polymerization is not limited as long as the polymerizable liquid crystal component exhibits the desired alignment, and can be appropriately set according to the haze desired for the diffusion film, the distance between the electrodes, etc. For example, by using a substrate with a transparent electrode layer as the first substrate and / or the second substrate, there is no need to prepare separate electrodes, and the distance between the electrodes can be reduced to reduce the applied voltage.

[0080] 3(a) and (b) show an example in which a liquid crystal component with positive dielectric anisotropy is used, but a diffusion layer can be similarly produced when a liquid crystal component with negative dielectric anisotropy is used. In this case, as shown in FIG. 4, in the A1 region (irradiated region) of the diffusion film 100B, the liquid crystal polymer 22 and the non-polymerizable liquid crystal component 26 contained in the dispersed particles 20 are typically oriented in a direction perpendicular to the electric field direction (thickness direction). When a liquid crystal component with negative dielectric anisotropy is used, a diffusion layer with high haze in the A1 region can be suitably obtained.

[0081] (Process IV) In step IV, a second substrate is disposed on the side of the PDLC layer or the diffusion layer opposite to the side on which the first substrate is disposed. Any suitable substrate may be used as the second substrate, and the above-mentioned second supporting substrate may be preferably used. The timing of carrying out step IV may be before step III, i.e., before polymerizing the polymerizable liquid crystal component, or after step III, i.e., after polymerizing the polymerizable liquid crystal component.

[0082] According to the method for manufacturing a diffusion film including step IV, by using a first supporting substrate and a second supporting substrate as the first substrate and the second substrate, respectively, a diffusion film having the first supporting substrate and the second supporting substrate and a diffusion layer directly sandwiched therebetween can be obtained.

[0083] To obtain sufficient adhesion, the second substrate is laminated on the PDLC layer or the diffusion layer, preferably using a laminator, while applying a lamination pressure of 0.006 MPa / m to 7 MPa / m, more preferably 0.06 MPa / m to 0.7 MPa / m.

[0084] <<Variation 1>> FIG. 5 is a schematic cross-sectional view for explaining the configuration of another example of the diffusion film according to the embodiment of the present invention. The diffusion film 100C shown in FIG. 5 includes a diffusion layer 110, a first support substrate 120 arranged on one side of the diffusion layer 110, and a second support substrate 130 arranged on the other side. The diffusion layer 110 has an A1 region including a polymer matrix 10 and dispersed particles 20 including a liquid crystal polymer 22 and a non-polymerizable liquid crystal component 26 that are dispersed in the polymer matrix 10 and aligned in a predetermined direction (thickness direction in the illustrated example), and a B1 region including a polymer matrix 10 and dispersed particles 20 including a liquid crystal polymer 22 and a non-polymerizable liquid crystal component 26 in a non-oriented state that are dispersed in the polymer matrix 10. The diffusion film 100C is different from the diffusion film 100A in that the dispersed particles 20 in the B1 region include a liquid crystal polymer 22 in a non-oriented state. In the diffusion film 100C, the alignment states of the liquid crystal polymer 22 contained in the dispersed particles 20 are different between the A1 region and the B1 region.

[0085] Diffusion film 100C has a mechanism similar to that of diffusion film 100A such that in area A1, light incident at a predetermined incident angle θ° (where θ>0) exhibits the maximum straight-line transmitted light intensity, and in area B1, light incident from the front direction exhibits the maximum straight-line transmitted light intensity.

[0086] Diffusion film 100C can be produced, for example, in the above-mentioned diffusion film manufacturing method, by irradiating the non-active energy ray-irradiated region (B1 region) with active energy rays in a state where no voltage is applied (as a result, the polymerizable liquid crystal component is in a non-oriented state) after the A1 region is produced, thereby polymerizing the polymerizable liquid crystal component.

[0087] <<Variation 2>> The diffusion film according to the embodiment of the present invention may include a diffusion layer having only the A1 region. Specifically, the entire region of the diffusion layer may include a polymer matrix, and dispersed particles that are dispersed in the polymer matrix and include a liquid crystal polymer oriented in a predetermined direction (for example, the thickness direction or a direction perpendicular to the thickness direction) and a non-polymerizable liquid crystal component as an optional component. Such a diffusion film can be produced by irradiating the entire region of the PDLC layer with active energy rays while the polymerizable liquid crystal component in the liquid crystal droplets is oriented in a predetermined direction, thereby polymerizing the polymerizable liquid crystal component.

[0088] B. Light Diffuser The light diffusion device according to the embodiment of the present invention includes the diffusion film described in Section A and a light source unit. Fig. 6 is a schematic cross-sectional view showing the configuration of a light diffusion device according to one embodiment of the present invention. The light diffusion device 300 includes a light source unit 350 and a diffusion film 100 disposed thereon.

[0089] The light source unit 350 has, for example, a reflective layer 310, a plurality of point light sources 320 provided on one side of the reflective layer 310, and a sealing unit 330 that seals the point light sources 320. The reflective layer may include, for example, a metal layer or a foamed resin layer. The plurality of point light sources are, for example, two-dimensionally arranged in a predetermined pattern. For example, LED elements can be used as the point light sources. The sealing unit 330 is made of, for example, a thermosetting resin such as a silicone resin or an epoxy resin.

[0090] In one embodiment, the diffusion film 100 has an A1 region formed in a pattern corresponding to the arrangement pattern of the point light source and a B1 region formed in this order so as to surround the outside of the A1 region, and can be laminated on the light source unit 350 so that the A1 region is located above the point light source. With this configuration, the light emitted from the point light source is highly diffused in an oblique direction in the high haze region (A1 region) arranged directly above, and the light reflected from the reflective layer can be transmitted upward in the B1 region surrounding the periphery. Since the B1 region is not directly above the LED, it is likely to become dark, and it is necessary for the B1 region to have a low haze. Therefore, rather than controlling the light distribution, it is possible to make the B1 region low haze and brighten the brightness of the B1 region by designing the average refractive index of the liquid crystal component when not aligned to be equal to the refractive index of the resin for forming the polymer matrix. With the light diffusion device having the above configuration, excellent uniformity of in-plane brightness and high light utilization efficiency can be realized. EXAMPLES

[0091] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The methods for measuring the various properties are as follows. In addition, unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight.

[0092] <Thickness> The measurement was performed using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). <Volume average particle size of liquid crystal particles in liquid crystal emulsion> The volume average particle diameter was calculated using a particle size distribution measuring device (manufactured by Microtrac, "MT3300EXII"). <Haze> The haze was measured according to JIS K 7136 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH4000"). <Refractive index of polymer matrix> The measurements were made using a prism coupler (manufactured by Meritcon, product name "2010 / M") as follows. 3 g of an aqueous dispersion of a polymer matrix-forming resin was dropped onto a PET film and dried at room temperature for 3 days to obtain a resin film with a thickness of 1.5 mm. The resin film was peeled off from the PET film, and the peeled surface was attached to a prism. A 594 nm laser beam was irradiated from the prism surface opposite to the resin film at 25°C. The refractive index of the polymer matrix was measured by measuring the reflected light intensity when the incident angle of the laser beam was changed. <Refractive index of liquid crystal components> The measurements were made using an Abbe refractometer (manufactured by Atago Co., Ltd., product name "NAR-4T"), as follows: Liquid crystal that had been heated to an isotropic state was dropped onto the prism surface that had been subjected to the orientation treatment, and then cooled to room temperature (25°C). With the liquid crystal oriented perpendicular to the prism surface, the angle of the polarizing plate placed above the eyepiece of the refractometer was changed to measure no and ne. The measurement wavelength used was the sodium D line (589.3 nm).

[0093] [Example 1] <Preparation of emulsion coating liquid> A mixture of 52.8 parts of a non-polymerizable liquid crystal component (manufactured by JNC Corporation, product name "JC-5240XX", positive type liquid crystal, birefringence Δn = 0.252 (ne = 1.766, no = 1.514), viscosity = 75 mPa s), 5.9 parts of a polymerizable liquid crystal component (manufactured by BASF Corporation, product name "PALIOCOLOR LC-242", birefringence Δn = 0.131 (ne = 1.654, no = 1.523)), 0.1 parts of a photopolymerization initiator (manufactured by IGM Corporation, product name "OMNIRAD651"), 40.0 parts of pure water, and 1.2 parts of a dispersant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name "Noigen ET159") was mixed and stirred with a homogenizer at 100 rpm for 10 minutes to obtain a crude dispersion. The crude dispersion was passed through a separation membrane with a uniform particle size distribution (SPG Techno Co., Ltd., product name "SPG Pumping Connector", pore size 10 μm) at room temperature from the outside to the inside of the membrane at a flow rate of 80 mL / min / cm. 2 This operation was repeated five times. The volume average particle size of the liquid crystal particles in the liquid crystal emulsion obtained was 3.0 μm. 30.8 parts of the above liquid crystal emulsion, 61.1 parts of an aqueous dispersion of an acrylic-styrene copolymer resin (refractive index 1.56) (solid content 29.0%), 0.2 part of a leveling agent (manufactured by DIC Corporation, product name "F-444"), 1.3 parts of a crosslinking agent (tris[3-(2-methylaziridin-1-yl)propionic acid]=propylidine trimethyl), and 5.2 parts of pure water were mixed to obtain an emulsion coating liquid. Note that the no of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component a is 1.515, and the ne a is 1.755.

[0094] <Fabrication of the support substrate> An ITO layer was formed on one side of a PET substrate (thickness: 50 μm) by sputtering to fabricate a support substrate having a structure of [substrate body / transparent electrode layer (surface resistance: 100 Ω)], which was used as the first support substrate and the second support substrate.

[0095] <Fabrication of the PDLC film> The above emulsion coating liquid was applied to the surface of the transparent electrode layer of the first support substrate with a wire bar to form a coating layer with a thickness of 30 μm. Then, the coating layer was dried at 25°C for 60 minutes to form a PDLC layer with a thickness of 8 μm. The obtained PDLC layer showed a uniform haze (haze (front direction): 90%) over the entire main surface. Next, while applying a lamination pressure of 0.4 MPa / m using a laminator, the second support substrate was laminated on the above PDLC layer to obtain PDLC film 1. The lamination of the second support substrate was performed such that the surface of the transparent electrode layer side faced the PDLC layer.

[0096] <Fabrication of the diffusion film> While applying a voltage of 100 V between the transparent electrode layers of PDCL film 1, UV irradiation was performed from the side of the second support substrate through a photomask having a predetermined pattern. Specifically, under a UV-LED lamp (manufactured by Hamamatsu Photonics, product name "C11924-101", peak wavelength 365 nm) at 20 mW / cm 2The film was exposed to light at 25°C for 3 minutes. This caused the polymerizable liquid crystal component in the irradiated area to polymerize, resulting in a diffusion film 1 having a structure of [first supporting substrate / patterned diffusion layer / second supporting substrate]. In the resulting diffusion film 1, the haze (front direction) of the irradiated area (area A1) was 38%.

[0097] [Example 2] <Preparation of emulsion coating liquid> 52.8 parts of a non-polymerizable liquid crystal component (negative type liquid crystal, birefringence Δn=0.149 (ne=1.633, no=1.484)), 5.9 parts of a polymerizable liquid crystal component (manufactured by BASF, product name "PALIOCOLOR LC-242", birefringence Δn=0.131 (ne=1.654, no=1.523)), 0.1 parts of a photopolymerization initiator (manufactured by IGM, product name "OMNIRAD651"), 40.0 parts of pure water, and 1.2 parts of a dispersant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name "Noigen ET159") were mixed and stirred with a homogenizer at 100 rpm for 10 minutes to obtain a crude dispersion. The crude dispersion was passed through a separation membrane with a uniform particle size distribution (SPG Techno Co., Ltd., product name "SPG Pumping Connector", pore size 10 μm) at room temperature from the outside to the inside of the membrane at a flow rate of 80 mL / min / cm. 2 This operation was repeated five times. The volume average particle size of the liquid crystal particles in the obtained liquid crystal emulsion was 3.0 μm. An emulsion coating liquid was obtained by mixing 30.8 parts of the above liquid crystal emulsion, 61.1 parts of an aqueous dispersion (solid content 29.0%) of acrylic-styrene copolymer resin (refractive index 1.56), 0.2 parts of a leveling agent (manufactured by DIC, product name "F-444"), 1.3 parts of a crosslinking agent (tris[3-(2-methylaziridin-1-yl)propionic acid]=propylidinetrimethyl), and 5.2 parts of pure water. In addition, the no of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component a is 1.488, and ne a was 1.635.

[0098] A PDLC film 2 was produced in the same manner as in Example 1, except that the above emulsion coating liquid was used, and then a diffusion film 2 was produced. In the PDLC film 2, the PDLC layer exhibited uniform haze (haze (front direction): 77%) over the entire main surface. In the diffusion film 2, the haze (front direction) of the irradiated area (area A1) was 82%.

[0099] [Comparative Example 1] <Preparation of emulsion coating liquid> A mixture of 52.8 parts of a non-polymerizable liquid crystal component (birefringence Δn=0.367 (ne=1.882, no=1.514), 5.9 parts of a polymerizable liquid crystal component (BASF, product name "PALIOCOLOR LC-242", birefringence Δn=0.131 (ne=1.654, no=1.523)), 0.1 parts of a photopolymerization initiator (IGM, product name "OMNIRAD651"), 40.0 parts of pure water, and 1.2 parts of a dispersant (Dai-ichi Kogyo Seiyaku, product name "Noigen ET159") was stirred at 100 rpm for 10 minutes with a homogenizer to obtain a crude dispersion. The crude dispersion was passed through a separation membrane with a uniform particle size distribution (SPG Techno, product name "SPG Pumping Connector", pore size 10 μm) at room temperature from the outside to the inside of the membrane at a flow rate of 80 mL / min / cm. 2 This operation was repeated five times. The volume average particle size of the liquid crystal particles in the obtained liquid crystal emulsion was 3.0 μm. An emulsion coating liquid was obtained by mixing 30.8 parts of the above liquid crystal emulsion, 44.3 parts of an aqueous dispersion of polyether-based polyurethane resin (manufactured by DSM, product name "NeoRez R967", refractive index 1.49, average polymer particle size: 80 nm, solid content: 40 wt%), 0.2 parts of a leveling agent (manufactured by DIC, product name "F-444"), 1.3 parts of a crosslinking agent (tris[3-(2-methylaziridin-1-yl)propionic acid] = propylidine trimethyl), and 22.0 parts of pure water. In addition, the no of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component a is 1.515, and ne a was 1.859.

[0100] A PDLC film C1 was produced in the same manner as in Example 1, except that the above emulsion coating liquid was used, and then a diffusion film C1 was produced. In the PDLC film C1, the PDLC layer exhibited uniform haze (haze (front direction): 80%) over the entire main surface. In the diffusion film 2, the haze (front direction) of the irradiated area (area A1) was 9%.

[0101] <Light distribution measurement> For the diffusion films obtained in the examples and comparative examples, light distribution was measured using a goniophotometer (manufactured by Nikka Densoku Co., Ltd., product name "GP-4"). Specifically, the light distribution was evaluated by measuring the intensity of straight transmitted light while varying the incident angle in 5° increments in the irradiated area (area A1) and non-irradiated area (area B1) of the diffusion film. The results are shown in Figure 7. In the figure, the vertical axis represents the ratio of each straight transmitted light intensity to the maximum straight transmitted light intensity.

[0102] As shown in Fig. 7, the diffusion film of Example 1 exhibited a maximum straight transmitted light intensity at an incident angle of about 30° in the A1 region, and a maximum straight transmitted light intensity at an incident angle of 0° in the B1 region. The diffusion film of Example 2 exhibited a maximum straight transmitted light intensity at an incident angle of about 60° in the A1 region, and a maximum straight transmitted light intensity at an incident angle of 0° in the B1 region. On the other hand, the diffusion film of Comparative Example 1 exhibited a maximum straight transmitted light intensity at an incident angle of 0° in both the A1 region and the B1 region. [Industrial Applicability]

[0103] The diffusion film of the present invention is suitably used in light diffusion devices and the like. [Explanation of symbols]

[0104] 10 Polymer matrix 20 Dispersed particles 22 Liquid crystal polymer 24 Polymerizable Liquid Crystal Components 26 Non-polymerizable liquid crystal components 100A, B Diffusion film 110 Diffusion Layer 120 First support base material 130 Second support base material 300 Light Diffuser

Claims

1. The present invention includes a diffusion layer including a polymer matrix and dispersed particles dispersed in the polymer matrix, the dispersed particles including a liquid crystal polymer that is a polymer of a polymerizable liquid crystal component and a non-polymerizable liquid crystal component as an optional component, The diffusion layer has an A1 region that exhibits a maximum straight-transmitted light intensity at an incident angle of θ° (where θ>0) and a B1 region that exhibits a maximum straight-transmitted light intensity at an incident angle of 0°, The alignment state and / or the content ratio of the liquid crystal polymer contained in the dispersed particles are different in the A1 region and the B1 region. Diffusion film.

2. The diffusion film according to claim 1 , wherein the A1 region contains the liquid crystal polymer in which the dispersed particles are oriented in a predetermined direction.

3. The diffusion film according to claim 2 , wherein the predetermined direction is a thickness direction or a direction perpendicular to the thickness direction.

4. The average ordinary refractive index of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component is no ａ , the average extraordinary refractive index is n e ａ When the refractive index of the polymer matrix is ​​np, no ａ <np<ne ａ The diffusion film according to claim 1 , which satisfies the following relationship:

5. 0.01≦np-no ａ and / or 0.01≦ne ａ The diffusion film according to claim 4, which satisfies the relationship -np.

6. 2. The diffusion film according to claim 1, wherein the content of said liquid crystal polymer in said A1 region is 5% by weight or more with respect to the total content of said liquid crystal polymer and said non-polymerizable liquid crystal component.

7. The present invention includes a diffusion layer including a polymer matrix and dispersed particles dispersed in the polymer matrix, the dispersed particles including a liquid crystal polymer that is a polymer of a polymerizable liquid crystal component and a non-polymerizable liquid crystal component as an optional component, The average ordinary refractive index of the polymerizable liquid crystal component and the non-polymerizable liquid crystal component is no ａ , the average extraordinary refractive index is n e ａ When the refractive index of the polymer matrix is ​​np, no ａ <np<ne ａ Satisfy the relationship Diffusion film.

8. 8. The diffusion film according to claim 7, wherein the diffusion layer has a region containing the liquid crystal polymer in which the dispersed particles are oriented in a predetermined direction and the non-polymerizable liquid crystal component as an optional component.

9. The diffusion film according to claim 8 , wherein the predetermined direction is a thickness direction or a direction perpendicular to the thickness direction.

10. The diffusion film according to claim 1 or 7, further comprising a supporting substrate disposed on one or both sides of the diffusion layer.

11. A light diffusing device comprising: a light source unit; and the diffusion film according to claim 1 .

12. The light diffusing device according to claim 11 , wherein the light source section includes a plurality of point light sources.

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