Light diffusion controller and reflective display

Abstract

The present invention provides a light diffusion control body capable of realizing a display body with excellent visibility, and a reflective display body with excellent visibility. The light diffusion control body is a light diffusion control body (1) having at least two light diffusion control layers, wherein the light diffusion control layer has a regular internal structure having a plurality of relatively high refractive index regions in a relatively low refractive index region, and when the normal direction of each of the first light diffusion control layer (11) and the second light diffusion control layer (12) as two layers in the light diffusion control layer (1) is set to 0° and light is sequentially irradiated at an incident angle of ‑70° to 70°, the minimum haze value measured is 35% or more.

Description

Technical Field

[0001] The present invention relates to a light diffusion control body capable of transmitting and diffusing incident light within a predetermined incident angle range in a state of intense light transmission with low light loss, and a reflective display body having the light diffusion control body. Background Art

[0002] Displays such as liquid crystal display devices, organic electroluminescence, and electronic paper are roughly divided into transmissive displays and reflective displays. Transmissive displays have a light source such as a backlight inside, and what the observer recognizes is the display illuminated from behind by the light source. In contrast, reflective displays do not have a light source such as a backlight, and use external indoor lighting, the sun, etc. as a light source. In addition, reflective displays also include reflective displays with the following system, that is, when the amount of light from the outside is insufficient at night, etc., a light source is set on the surface side of the display so that it can be recognized by indirect lighting. Moreover, reflective displays usually have a reflector inside. Reflective displays use a reflector to reflect light from an external light source, and the display is illuminated by the reflected light.

[0003] Since the reflective display uses an external light source, the positional relationship between the light source and the observer is not fixed. As a result, depending on the position of the light source, it is easy to cause problems such as insufficient light reaching the observer, reduced visibility, or inability to brightly illuminate the entire display. In order to solve such technical problems, it is possible to consider assembling a light diffusion plate on the display. However, if only a general light diffusion plate is assembled, there is a problem that the diffusion necessary for obtaining good visibility cannot be fully obtained, or if high diffusion is desired, light loss caused by stray light or backscattering occurs, and image clarity is impaired. From the perspective of solving these problems, it is being studied to set a light diffusion control body between the surface on the observer side and the reflector in the reflective display, which can make the incident light within a specified incident angle range be transmitted and diffused in a strong and low light loss state. By having the above-mentioned light diffusion control body, the light reflected by the reflector is appropriately diffused, and the reduction in visibility dependent on the position of the light source is reduced.

[0004] As a reflective display body having a light diffusion control body as described above, Patent Document 1 discloses a display device comprising a reflective display panel and an optical laminate arranged on the display panel, wherein the optical laminate has two or more anisotropic scattering films, at least two of the plurality of anisotropic scattering films have transmittances in the direction of a scattering central axis that are different from each other, and a first film having a relatively high transmittance in the direction of a scattering central axis of the anisotropic scattering film included in the optical laminate has a transmittance in the direction of a scattering central axis that is four times or more as high as a second film having a relatively low transmittance in the direction of a scattering central axis of the anisotropic scattering film included in the optical laminate.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5749960 Summary of the invention

[0008] Technical Problems to be Solved by the Invention

[0009] However, in recent years, the application scope of reflective display bodies such as liquid crystal display devices and electronic paper has been continuously expanded, and with this, higher visibility or performance that can be recognized even under worse light sources has gradually begun to be required. As a result, the conventional reflective display body disclosed in Patent Document 1 has become unable to meet the required performance, and a light diffusion control body that can achieve better visibility is sought.

[0010] The present invention has been made in view of such actual circumstances, and an object of the present invention is to provide a light diffusion control body capable of realizing a display body having excellent visibility, and a reflective display body having excellent visibility.

[0011] Technical means to solve technical problems

[0012] In order to achieve the above-mentioned purpose, first, the present invention provides a light diffusion control body, which has at least two light diffusion control layers, and the light diffusion control layers have a regular internal structure having multiple relatively high refractive index regions in a relatively low refractive index region. The light diffusion control body is characterized in that, for each single surface of the first light diffusion control layer and the second light diffusion control layer, which are two layers of the light diffusion control layer, the normal direction of the surface is set to 0°, and light is irradiated sequentially at incident angles of -70° to 70°, and the minimum haze value measured is 35% or more (Invention 1).

[0013] The light diffusion control body of the above invention (Invention 1) can appropriately diffuse light by having a first light diffusion control layer and a second light diffusion control layer each having the minimum haze value. Therefore, a reflective display body having the light diffusion control body can also effectively utilize light incident from a more biased direction, and has excellent visibility.

[0014] In the above invention (Invention 1), it is preferable that a diffusion center axis of the first light diffusion control layer and a diffusion center axis of the second light diffusion control layer have different angles (Invention 2).

[0015] In the above inventions (Inventions 1 and 2), it is preferred that the regular internal structure in at least one of the first light diffusion control layer and the second light diffusion control layer is a columnar structure in which a plurality of columns with relatively high refractive index are arranged in a row along the film thickness direction of the film in the region with relatively low refractive index (Invention 3).

[0016] Second, the present invention provides a reflective display, characterized in that it includes the light diffusion control body (Inventions 1 to 3) and a reflective plate provided on one side of the light diffusion control body (Invention 4).

[0017] Effects of the Invention

[0018] According to the light diffusion controller of the present invention, a display having excellent visibility, particularly a reflective display, can be produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a cross-sectional view of a light diffusion control body according to one embodiment of the present invention.

[0020] Figure 2 This is a perspective view schematically showing an example (column structure) of a regular internal structure of a light diffusion control layer according to one embodiment of the present invention.

[0021] Figure 3 This is a cross-sectional view of a reflective display including a light diffusion controller according to one embodiment of the present invention.

[0022] Figure 4 This is a diagram showing the results of Test Example 1 (measurement of the variable angle haze of the light diffusion control layer).

[0023] Figure 5-1 This is a diagram showing part of the results of Test Example 2 (measurement of diffusion brightness distribution of light diffusion control layer).

[0024] Figure 5-2 This is a diagram showing part of the results of Test Example 2 (measurement of diffusion brightness distribution of light diffusion control layer).

[0025] Figure 6-1 This is a diagram showing part of the results of Test Example 3 (measurement of diffuse brightness distribution of a reflective display sample).

[0026] Figure 6-2 This is a diagram showing part of the results of Test Example 3 (measurement of diffuse brightness distribution of a reflective display sample).

[0027] Figure 6-3 This is a diagram showing part of the results of Test Example 3 (measurement of diffuse brightness distribution of a reflective display sample).

[0028] Figure 6-4This is a diagram showing part of the results of Test Example 3 (measurement of diffuse brightness distribution of a reflective display sample).

[0029] Figure 7 This is a diagram showing a graph obtained from the results of Test Example 3 (diffuse luminance distribution measurement of a reflective display sample).

[0030] Figure 8 It is a figure which shows the result of Test Example 4 (Evaluation of visibility of reflective display sample).

[0031] Description of Reference Numerals

[0032] 1: light diffusion control body; 11: first light diffusion control layer; 12: second light diffusion control layer; 112: columnar object with relatively high refractive index; 113: columnar structure; 114: region with relatively low refractive index; 2: reflective display body; 21: reflective plate. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present invention will be described.

[0034] [Light diffusion control body]

[0035] Figure 1 2 is a cross-sectional view of a light diffusion control body according to an embodiment of the present invention. Figure 1 The light diffusion control body 1 shown has at least two light diffusion control layers, and the light diffusion control layer has a regular internal structure having a plurality of regions with a relatively high refractive index in a region with a relatively low refractive index. Here, the regular internal structure refers to an internal structure in which a plurality of regions with a relatively high refractive index are arranged with a predetermined regularity in a region with a relatively low refractive index (for example, when observing the following cross section, in a region with a relatively low refractive index, regions with a relatively high refractive index are repeatedly arranged at the same distance along at least one direction in the cross section, and the cross section is a cross section obtained by cutting the light diffusion control layer with a plane parallel to the surface of the light diffusion control layer, and is a cross section obtained by cutting at a position where the regular internal structure exists).

[0036] In particular Figure 1The light diffusion control body 1 shown includes a first light diffusion control layer 11, and a second light diffusion control layer 12 stacked on one side of the first light diffusion control layer 11. In addition, the light diffusion control body 1 of the present embodiment may further include a light diffusion control layer other than the first light diffusion control layer 11 and the second light diffusion control layer 12, or may further include a layer other than the light diffusion control layer. In addition, as long as the light diffusion control body 1 includes the first light diffusion control layer 11 and the second light diffusion control layer 12, its form is not particularly limited, for example, it may be in the form of a general component assembled into a display body, and is particularly preferably in the form of a film, that is, preferably a light diffusion control film.

[0037] In the light diffusion control body 1 of the present embodiment, for each single surface of the first light diffusion control layer 11 and the second light diffusion control layer 12, the normal direction of the surface is set to 0°, and when light is sequentially irradiated at an incident angle of -70° to 70°, the minimum value of the measured haze value is 35% or more. The light diffusion control body 1 of the present embodiment has at least two layers of the light diffusion control layer with a minimum haze value of 35% or more, so that the light incident on the light diffusion control body 1 at a specified angle can be appropriately diffused and transmitted. Therefore, when the light diffusion control body 1 of the present embodiment is used to manufacture a reflective display, for the reflective display, even when the incident angle of the incident light (the angle between the normal line of the display surface of the reflective display and the incident light) is larger, the incident light effectively reaches the direction of the observer. As a result, the observer can recognize the display more clearly, that is, excellent visibility can be achieved. The transmissive display manufactured using the light diffusion control body 1 of the present embodiment can also achieve such excellent visibility.

[0038] From the perspective of achieving better visibility, the minimum value of the haze value of at least one of the first light diffusion control layer 11 and the second light diffusion control layer 12 (preferably both layers) is preferably 40% or more, more preferably 50% or more, particularly preferably 60% or more, and further preferably 65% ​​or more.

[0039] In addition, the maximum value of the haze value is preferably 80% or more, more preferably 85% or more, particularly preferably 90% or more, and further preferably 95% or more in at least one of the first light diffusion control layer 11 and the second light diffusion control layer 12 (preferably in both layers). By making the maximum value of the haze value in at least one of the first light diffusion control layer 11 and the second light diffusion control layer 12 (preferably in both layers) as described above, it is easy to make a clearer display reach the observer.

[0040] The minimum and maximum values ​​of the above haze values ​​can be obtained by variable angle haze measurement using a variable angle haze meter or the like, and the details of the measurement method are described in the test examples described later.

[0041] In the light diffusion control body 1 of the present embodiment, the difference in haze value between the first light diffusion control layer 11 and the second light diffusion control layer 12 is preferably less than 50 percentage points, particularly preferably less than 30 percentage points, further preferably less than 10 percentage points, and further preferably less than 5 percentage points. By making the difference in the above haze value less than 50 percentage points, the first light diffusion control layer 11 and the second light diffusion control layer 12 are easy to have the minimum value of the above haze value. In addition, there is no particular limitation on the lower limit of the difference in the above haze value, for example, it can be more than 0.1 percentage point, particularly more than 0.5 percentage point, and further more than 1 percentage point. In addition, the haze value in the difference in the above haze value is the haze value measured when each light diffusion control layer is irradiated with light at an incident angle of 0°.

[0042] In the light diffusion control body 1 of the present embodiment, the diffusion center axis of the first light diffusion control layer 11 and the diffusion center axis of the second light diffusion control layer 12 are preferably at different angles. As a result, the light diffusion control body 1 of the present embodiment is more likely to disperse light incident at a specified angle. Therefore, the reflective display body having the light diffusion control body 1 of the present embodiment is more likely to reflect incident light with a larger incident angle toward the observer, thereby achieving better visibility. In addition, the above-mentioned diffusion center axis refers to an axis about which the diffusion characteristics are roughly symmetrical, and can be inferred based on the diffusion performance obtained by measuring the variable angle haze of the light diffusion control layer, and the detailed measurement method is shown in the description of the test example described later.

[0043] In addition, from the perspective of further facilitating excellent visibility, the angle between the diffusion center axis of the first light diffusion control layer 11 and the diffusion center axis of the second light diffusion control layer 12 is preferably 1° or more, particularly preferably 5° or more, and further preferably 10° or more. In this way, by making the angle between the diffusion center axes be within the above range, the light diffusion control body 1 of the present embodiment can more easily disperse light incident at a predetermined angle.

[0044] On the other hand, the angle between the diffusion center axis of the first light diffusion control layer 11 and the diffusion center axis of the second light diffusion control layer 12 is preferably 40° or less, particularly preferably 30° or less, and further preferably 20° or less. By making the angle between the diffusion center axes within the above range, the range of effective diffusion of the emitted light is easy to overlap the first light diffusion control layer 11 and the second light diffusion control layer 12, and as a result, it is easy to achieve better visibility.

[0045] In the light diffusion control body 1 of the present embodiment, it is preferred that the light is irradiated on one side of the first light diffusion control layer 11 at an incident angle that diffuses the incident light most strongly, and the ratio of the maximum value of the light intensity of the diffused light transmitted to the other side to the maximum value of the light intensity of the diffused light obtained by measuring the second light diffusion control layer 12 in the same manner (the ratio obtained by dividing the larger value by the smaller value) is less than 4 times, more preferably 3.5 times or less, further preferably 3 times or less, further preferably 2 times or less, and most preferably 1.4 times or less. By making the above ratio less than 4 times, the first light diffusion control layer 11 and the second light diffusion control layer 12 are easy to have the minimum value of the above haze value. On the other hand, there is no particular limitation on the lower limit of the above ratio, for example, it can be 1.00 times or more, particularly 1.01 times or more, and further 1.05 times or more. In addition, the maximum value of the light intensity of the diffused light can be obtained, for example, by measuring the diffuse brightness distribution of the light diffusion control layer using a diffuse brightness distribution measuring device, and the details of the measuring method are shown in the description of the test example described later.

[0046] 1. Composition of light diffusion control layer

[0047] The first light diffusion control layer 11 and the second light diffusion control layer 12 of the light diffusion control body of the present embodiment are not particularly limited as long as they have a regular internal structure having a plurality of relatively high refractive index regions in a relatively low refractive index region and have the above-mentioned minimum haze value. In addition, when the light diffusion control body of the present embodiment further has a light diffusion control layer other than the first light diffusion control layer 11 and the second light diffusion control layer 12, the light diffusion control layer other than the first light diffusion control layer 11 and the second light diffusion control layer 12 is not particularly limited as long as it has a regular internal structure having a plurality of relatively high refractive index regions in a relatively low refractive index region.

[0048] The first light diffusion control layer 11, the second light diffusion control layer 12, and the light diffusion control layer other than the first light diffusion control layer 11 and the second light diffusion control layer 12 are preferably obtained by curing a light diffusion control layer composition containing a high refractive index component and a low refractive index component, wherein the low refractive index component has a refractive index lower than that of the high refractive index component. It is particularly preferred that the high refractive index component and the low refractive index component each have 1 or 2 polymerizable functional groups. By using such a light diffusion control layer composition, it is easy to form the above-mentioned regular internal structure well, and at the same time, when forming the first light diffusion control layer 11 and the second light diffusion control layer 12, it is also easy to adjust the haze value, and as a result, it is easy to achieve the minimum value of the above-mentioned haze value.

[0049] (1) High refractive index component

[0050] As the preferred example of the above-mentioned high refractive index component, (meth) acrylate containing aromatic ring can be listed, and (meth) acrylate containing multiple aromatic rings can be listed particularly preferably. As the example of (meth) acrylate containing multiple aromatic rings, biphenyl (meth) acrylate, naphthyl (meth) acrylate, anthracene (meth) acrylate, benzylphenyl (meth) acrylate, biphenyloxyalkyl (meth) acrylate, naphthyloxyalkyl (meth) acrylate, anthracene (meth) acrylate, benzylphenoxyalkyl (meth) acrylate, and compounds substituted by halogen, alkyl, alkoxy, haloalkyl, etc., and a part of these esters can be listed. Wherein, from the perspective of being easy to form a good regular internal structure, biphenyl (meth) acrylate is preferred, specifically, preferred o-phenylphenoxyethyl acrylate, o-phenylphenoxyethoxyethyl acrylate, etc. In addition, in this manual, (meth) acrylic acid refers to both acrylic acid and methacrylic acid. Other similar terms are also the same.

[0051] The weight average molecular weight of the high refractive index component is preferably 2500 or less, particularly preferably 1500 or less, and further preferably 1000 or less. In addition, the weight average molecular weight of the high refractive index component is preferably 150 or more, particularly preferably 200 or more, and further preferably 250 or more. By making the weight average molecular weight of the high refractive index component within the above range, it is easy to form a light diffusion control layer having a desired regular internal structure, and it is easy to form the first light diffusion control layer 11 and the second light diffusion control layer 12 having the minimum haze value described above. In addition, the weight average molecular weight in this specification is a value converted to standard polystyrene measured by gel permeation chromatography (GPC).

[0052] The refractive index of the high refractive index component is preferably 1.45 or more, more preferably 1.50 or more, particularly preferably 1.54 or more, and further preferably 1.56 or more. In addition, the refractive index of the high refractive index component is preferably 1.70 or less, particularly preferably 1.65 or less, and further preferably 1.59 or less. By making the refractive index of the high refractive index component within the above range, it is easy to form a light diffusion control layer having a desired regular internal structure, and it is easy to form the first light diffusion control layer 11 and the second light diffusion control layer 12 having the minimum haze value mentioned above. In addition, the refractive index in this specification refers to the refractive index of the specified component before curing the light diffusion control layer composition, and the refractive index is measured according to JIS K0062:1992.

[0053] Relative to 100 parts by mass of the low refractive index component, the content of the high refractive index component in the composition for the light diffusion control layer is preferably 25 parts by mass or more, particularly preferably 40 parts by mass or more, and further preferably 50 parts by mass or more. In addition, relative to 100 parts by mass of the low refractive index component, the content of the high refractive index component in the composition for the light diffusion control layer is preferably 400 parts by mass or less, particularly preferably 300 parts by mass or less, and further preferably 200 parts by mass or less. By making the content of the high refractive index component within the above range, in the regular internal structure of the formed light diffusion control layer, the region originating from the high refractive index component and the region originating from the low refractive index component exist in a desired ratio. As a result, it is easy to form a light diffusion control layer having a desired regular internal structure, and it is easy to form the first light diffusion control layer 11 and the second light diffusion control layer 12 having the minimum haze value described above.

[0054] (2) Low refractive index component

[0055] Preferred examples of the low refractive index component include urethane (meth)acrylate, (meth)acrylic polymers having a (meth)acryloyl group on a side chain, (meth)acryloyl-containing silicone resins, unsaturated polyester resins, and the like. Urethane (meth)acrylate is particularly preferably used.

[0056] The urethane (meth)acrylate is preferably formed from (a) a compound containing at least two isocyanate groups, (b) a polyalkylene glycol, and (c) a hydroxyalkyl (meth)acrylate.

[0057] Preferred examples of the compound (a) containing at least two isocyanate groups include aromatic polyisocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate (IPDI) and hydrogenated diphenylmethane diisocyanate, and their biuret forms and isocyanurate forms, and further examples include adducts (for example, xylylene diisocyanate trifunctional adducts) as reaction products with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil, etc. Among them, alicyclic polyisocyanates are preferred, and alicyclic diisocyanates containing only two isocyanate groups are particularly preferred.

[0058] Preferred examples of the above-mentioned (b) polyalkylene glycol include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol, and the like. Among them, polypropylene glycol is preferred.

[0059] The weight average molecular weight of the polyalkylene glycol (b) is preferably 2300 or more, particularly preferably 4300 or more, and further preferably 6300 or more. The weight average molecular weight of the polyalkylene glycol (b) is preferably 19500 or less, particularly preferably 14300 or less, and further preferably 12300 or less.

[0060] Preferred examples of the above-mentioned (c) hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. Among them, 2-hydroxyethyl methacrylate is preferably used from the viewpoint of reducing the polymerization rate of the obtained urethane (meth)acrylate and being able to more effectively form a predetermined regular internal structure.

[0061] The synthesis of urethane (meth) acrylate using the above-mentioned components (a) to (c) as materials can be carried out according to a conventional method. At this time, from the perspective of effectively synthesizing urethane (meth) acrylate, the blending ratio of the components (a) to (c) at this time is preferably set to a ratio of (a) component: (b) component: (c) component = 1 to 5: 1: 1 to 5, particularly preferably a ratio of 1 to 3: 1: 1 to 3, and more preferably a ratio of 2: 1: 2, in terms of molar ratio.

[0062] The weight average molecular weight of the low refractive index component is preferably 3000 or more, particularly preferably 5000 or more, and further preferably 7000 or more. In addition, the weight average molecular weight of the low refractive index component is preferably 20000 or less, particularly preferably 15000 or less, and further preferably 13000 or less. By making the weight average molecular weight of the low refractive index component within the above range, it is easy to form a light diffusion control layer having a desired regular internal structure, and it is easy to form the first light diffusion control layer 11 and the second light diffusion control layer 12 having the minimum haze value described above.

[0063] The refractive index of the low refractive index component is preferably 1.59 or less, more preferably 1.50 or less, particularly preferably 1.49 or less, and further preferably 1.48 or less. In addition, the refractive index of the low refractive index component is preferably 1.30 or more, particularly preferably 1.40 or more, and further preferably 1.46 or more. By making the refractive index of the low refractive index component within the above range, it is easy to form a light diffusion control layer having a desired regular internal structure, and it is easy to form the first light diffusion control layer 11 and the second light diffusion control layer 12 having the minimum haze value mentioned above.

[0064] (3) Other ingredients

[0065] In addition to the high refractive index component and the low refractive index component, the composition for the light diffusion control layer may also contain other additives. Examples of other additives include multifunctional monomers (compounds having three or more polymerizable functional groups), photopolymerization initiators, antioxidants, ultraviolet absorbers, antistatic agents, polymerization accelerators, polymerization inhibitors, infrared absorbers, plasticizers, diluents, and leveling agents.

[0066] It is also preferred that the composition for light diffusion control layer contains a photopolymerization initiator among the above additives. When the composition for light diffusion control layer contains a photopolymerization initiator, it is easy to efficiently form a light diffusion control layer having a desired regular internal structure.

[0067] Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propane-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxyethoxy)phenyl-2-(

[0043] The photopolymerization initiator may be selected from the group consisting of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, 2-(2-hydroxy-2-methyl-2-(4-(1-methylvinyl)phenyl)propanone, 2-(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, 2-(2-hydroxy-2-methyl-2-(4-(1-methylvinyl)phenyl)propanone, 2-(2-hydroxy-2-methyl-2-(4-(1-methylvinyl)phenyl)propanone, 2-(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone], 2-(2-amino-2-methyl-2-(4-(1-methylvinyl)phenyl)propanone ...

[0068] When using a photopolymerization initiator, relative to the total amount of 100 parts by mass of the high refractive index component and the low refractive index component, the content of the photopolymerization initiator in the composition for the light diffusion control layer is preferably set to 0.2 parts by mass or more, particularly preferably to 0.5 parts by mass or more, and further preferably to 1 part by mass or more. In addition, relative to the total amount of 100 parts by mass of the high refractive index component and the low refractive index component, the content of the photopolymerization initiator is preferably set to 20 parts by mass or less, particularly preferably to 15 parts by mass or less, and further preferably to 10 parts by mass or less. By making the content of the photopolymerization initiator in the composition for the light diffusion control layer within the above range, it is easy to effectively form a light diffusion control layer.

[0069] (4) Preparation of Composition for Light Diffusion Control Layer

[0070] The composition for a light diffusion control layer can be prepared by uniformly mixing the above-mentioned high refractive index component and low refractive index component and other additives such as a photopolymerization initiator as required.

[0071] During the mixing, the mixture may be stirred while being heated to 40 to 80° C. to obtain a uniform composition for a light diffusion control layer. A diluting solvent may be added and mixed so that the obtained composition for a light diffusion control layer has a desired viscosity.

[0072] 2. Regular internal structure of the light diffusion control layer

[0073] As described above, the light diffusion control layer of the present embodiment has a regular internal structure in which a plurality of regions with relatively high refractive indexes are provided in a region with relatively low refractive indexes. More specifically, the light diffusion control layer of the present embodiment has a regular internal structure in which a plurality of regions with relatively high refractive indexes extend along the film thickness direction of the film at a predetermined length in a region with relatively low refractive indexes. In addition, the regular internal structure here is a structure in which a region with relatively high refractive indexes extends along the film thickness direction of the film, and in this respect, it is distinguished from a phase separation structure in which one phase exists in another phase without clear regularity, or a sea island structure in which an almost spherical island component exists in a sea component.

[0074] As a more specific example of the above-mentioned regular internal structure, a columnar structure in which a plurality of relatively high refractive index columns stand in a relatively low refractive index region along the film thickness direction of the film can be cited. In the first light diffusion control layer 11 and the second light diffusion control layer 12 of the present embodiment, it is preferred to have a columnar structure as the regular internal structure from the perspective of easily achieving the above-mentioned minimum haze value.

[0075] (1) Column structure

[0076] Figure 2 FIG. 2 is a perspective view schematically showing the above-mentioned column structure. Figure 2 As shown, the column structure 113 is a structure in which a plurality of columnar objects 112 with a relatively high refractive index stand in a thick direction and are surrounded by a region 114 with a relatively low refractive index. Figure 2 In the figure, although the columnar object 112 is drawn to exist in the entire region of the columnar structure 113 in the thickness direction, the columnar object 112 may not exist in at least one of the upper end and the lower end of the columnar structure 113 in the thickness direction.

[0077] When the incident angle of light incident on the light diffusion control layer having such a columnar structure 113 falls within a specified range, the light is strongly diffused at a specified angle and emitted from the light diffusion control layer. On the other hand, when the incident light is incident at an angle outside the above-mentioned incident angle range, it is transmitted but not diffused, or is emitted with a diffusion weaker than that of the incident light with an incident angle within the range. In addition, when the imaging body is arranged in a manner parallel to the surface of the light diffusion control layer, the diffused light generated by the columnar structure 113 is circular or substantially circular (elliptical, etc.) with expansion in any direction.

[0078] In the columnar structure 113, the difference between the refractive index of the columnar object 112 with a relatively high refractive index and the refractive index of the region 114 with a relatively low refractive index is preferably 0.01 or more, particularly preferably 0.05 or more, and further preferably 0.1 or more. By making the above difference 0.01 or more, effective diffusion can be performed. In addition, the upper limit of the above difference is not particularly limited, for example, it can be 0.3 or less.

[0079] Preferably, the columnar object 112 has a structure in which the diameter increases from one surface to the other surface of the light diffusion control layer. Compared with a columnar object whose diameter is almost constant from one surface to the other surface, the columnar object 112 having such a structure is easy to change the traveling direction of light parallel to the axis direction of the columnar object, thereby the light diffusion control layer can effectively diffuse the light.

[0080] In addition, the maximum value of the diameter of the cross section when the columnar object 112 is cut with a plane horizontal to the axial direction is preferably 0.1 μm or more, particularly preferably 0.5 μm or more, and further preferably 1 μm or more. In addition, the maximum value is preferably 15 μm or less, particularly preferably 10 μm or less, and further preferably 5 μm or less. By making the maximum value of the diameter within the above range, the light diffusion control layer can effectively diffuse light. In addition, although there is no particular limitation on the cross-sectional shape of the columnar object 112 when cut with a plane perpendicular to the axial direction, it is preferably a circle, an ellipse, a polygon, an irregular shape, etc.

[0081] In the columnar structure 113, the distance between adjacent columnar objects 112 is preferably 0.1 μm or more, particularly preferably 0.5 μm or more, and further preferably 1 μm or more. In addition, the above distance is preferably 15 μm or less, particularly preferably 10 μm or less, and further preferably 5 μm or less. By making the distance between adjacent columnar objects 112 within the above range, the light diffusion control layer can effectively diffuse light.

[0082] In addition, in the columnar structure 113, the columns 112 can be arranged horizontally in the thickness direction of the light diffusion control layer, or can be arranged at a certain inclination angle. The inclination angle when arranged at a certain inclination angle, that is, the angle of the acute angle between the axis of the columnar 112 of the columnar structure 113 and the normal line of the surface of the light diffusion control layer is preferably 1° or more, particularly preferably 5° or more, and further preferably 10° or more. In addition, the above angle is preferably 50° or less, particularly preferably 40° or less, and further preferably 30° or less. By tilting the columnar 112 within the above range, the light diffusion control layer having such a columnar structure 113 can diffuse the transmitted light while offsetting it in the desired direction.

[0083] Note that the dimensions, predetermined angles, and the like of the regular internal structure of the columnar structure 113 described above can be measured by observing a cross section of the columnar structure 113 using an optical digital microscope.

[0084] (2) Modification of column structure

[0085] The regular internal structure of the light diffusion control layer of this embodiment may be a structure obtained by deforming the above-mentioned columnar structure 113. For example, as the internal structure, the light diffusion control layer may have a structure in which the columnar object 112 in the above-mentioned columnar structure 113 is bent in the middle of the thickness direction of the light diffusion control layer. In addition, the light diffusion control layer may be a columnar structure 113 having a region of two or more columnar objects with different inclination angles in the thickness direction of the light diffusion control layer.

[0086] 3. Method for manufacturing light diffusion control body

[0087] The light diffusion control body of the present embodiment can be obtained by, for example, separately forming the first light diffusion control layer 11 and the second light diffusion control layer 12, and other layers such as the light diffusion control layer other than the first light diffusion control layer 11 and the second light diffusion control layer 12 as required, and then stacking them in a desired order. In addition, as another example of the manufacturing method, the light diffusion control layer 12 can be obtained by directly forming the second light diffusion control layer 12 on the first light diffusion control layer 11 after forming the first light diffusion control layer 11.

[0088] The method for forming the first light diffusion control layer 11, the second light diffusion control layer 12 and the light diffusion control layer other than the first light diffusion control layer 11 and the second light diffusion control layer 12 is not particularly limited, and can be formed using a conventionally known method. For example, after the above-mentioned light diffusion control layer composition is applied to one side of the process sheet and a coating is formed, a single side (especially the peeling side) of a release sheet is attached to the surface of the coating opposite to the process sheet. Then, the coating is irradiated with active energy rays through the process sheet or the release sheet to cure it, thereby forming a light diffusion control layer. In this way, by stacking the release sheet on the above-mentioned coating, the gap between the release sheet and the process sheet is maintained, the coating is prevented from being flattened, and a light diffusion control layer with a uniform thickness is easily formed.

[0089] Examples of the coating method include knife coating, roll coating, bar coating, blade coating, die coating, and gravure coating. The light diffusion control layer composition may be diluted with a solvent as necessary.

[0090] The coating film is irradiated with active energy rays in different ways depending on the regular internal structure to be formed. Such irradiation can be performed using conventionally known methods. For example, when forming the above-mentioned columnar structure, the coating film is irradiated with parallel light with high beam parallelism.

[0091] The active energy rays are electromagnetic waves or charged particle beams having energy quanta, and specific examples thereof include ultraviolet rays and electron beams. Among active energy rays, ultraviolet rays are particularly preferred because they are easy to handle.

[0092] When the column structure is formed by using ultraviolet rays as the active energy rays, the irradiation conditions are preferably such that the peak illuminance on the coating surface is 0.1 to 10 mW / cm 2 The peak illuminance here refers to the measured value of the portion where the active energy rays irradiated to the coating surface show the maximum value. Furthermore, it is preferred that the accumulated light intensity on the coating surface is set to 5 to 200 mJ / cm 2 .

[0093] In addition, from the perspective of achieving more reliable curing, after curing using parallel light or band light as described above, it is also preferred to irradiate with normal active energy rays (active energy rays that have not been converted into parallel light or band light, scattered light).

[0094] 4. Use of light diffusion controller

[0095] The use of the light diffusion control body 1 of the present embodiment is not particularly limited, and the light diffusion control body 1 can be used in the same manner as the conventional light diffusion control body. The light diffusion control body 1 of the present embodiment is particularly suitable for use in manufacturing a reflective display body.

[0096] Figure 3 2 shows a cross-sectional view of an example of a reflective display 2 manufactured using the light diffusion control body 1 of the present embodiment. The reflective display 2 includes the light diffusion control body 1 of the present embodiment and a reflective plate 21 provided on one side of the light diffusion control body 1.

[0097] In addition, the reflective display body 2 may include layers or components other than the light diffusion control body 1 and the reflector 21. For example, a display panel such as a liquid crystal may be provided between the light diffusion control body 1 and the reflector 21. Alternatively, the reflective display body 2 is a structure in which the light diffusion control body 1 is provided on one side of the display panel, and the reflector 21 may be provided as one of the components constituting the display panel.

[0098] Examples of the reflective display 2 include electronic devices such as reflective liquid crystal display devices, electronic paper, electrophoretic displays, MEMS displays, and solid crystal displays. In addition to such electronic devices, the reflective display 2 may also be a display having display contents printed on paper, resin films, metal plates, and the like. In this case, the paper, resin films, metal plates, and the like may function as the reflector 21, or printed paper, resin films, and the like for display may be provided between the light diffusion control body 1 and the reflector 21.

[0099] Furthermore, the light diffusion controller 1 of the present embodiment can also be used for the production of transmission type displays such as transmission type liquid crystal display devices and organic EL displays.

[0100] The light diffusion control body 1 of this embodiment has the first light diffusion control layer 11 and the second light diffusion control layer 12 each having the minimum haze value described above, thereby preventing light loss such as backscattered light and stray light and appropriately diffusing light. Thus, a display body (especially a reflective display body 2) manufactured using the light diffusion control body 1 can achieve excellent visibility.

[0101] The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments also includes all design changes or equivalents within the scope of protection of the present invention.

[0102] Example

[0103] Hereinafter, the present invention will be described in more detail using examples and the like, but the scope of the present invention is not limited to these examples and the like.

[0104] [Production Example 1] (Light Diffusion Control Layer A)

[0105] (1) Preparation of composition for light diffusion control layer

[0106] To 40 parts by mass of polyether urethane methacrylate having a weight average molecular weight of 9,900 as a low refractive index component (solid content conversion value; the same below), 60 parts by mass of o-phenylphenoxyethoxyethyl acrylate having a molecular weight of 268 as a high refractive index component and 8 parts by mass of 2-hydroxy-2-methyl-1-phenylpropane-1-one as a photopolymerization initiator were added, and then heated and mixed at 80° C. to obtain a composition for a light diffusion control layer. The polyether urethane methacrylate was obtained by reacting polypropylene glycol, isophorone diisocyanate and 2-hydroxyethyl methacrylate.

[0107] (2) Formation of light diffusion control layer

[0108] The obtained composition for light diffusion control layer was applied to one side of a long polyethylene terephthalate sheet as a process sheet to form a coating film. Next, a release sheet (manufactured by LINTEC CORPORATION, product name "SP-PET381130", thickness: 38 μm) obtained by releasing one side of the polyethylene terephthalate film with a silicone release agent was laminated on the opposite side of the coating film to the process sheet.

[0109] The laminated body consisting of the peeling sheet, the coating film and the process sheet thus obtained is placed on a conveyor. At this time, the surface of the peeling sheet side of the laminated body is made to be the upper side, and at the same time, the long side direction of the laminated body is made parallel to the conveying direction of the conveyor. Then, an ultraviolet point parallel light source (manufactured by JATEC CO., LTD.) is set on the conveyor on which the laminated body is placed, and the parallelism of the central beam is controlled within ±3°. At this time, the light source is set in a manner that can irradiate light in the normal direction of the surface parallel to the peeling sheet side of the laminated body.

[0110] Then, the conveyor was operated to move the laminate while the peak illuminance on the coating surface was 2.00 mW / cm 2 , the accumulated light intensity is 53.13mJ / cm 2 The coating film in the laminate was cured under the conditions of 2° or less parallel light (ultraviolet light from a high pressure mercury lamp having a main peak wavelength of 365 nm and peaks at 254 nm, 303 nm, and 313 nm) to form a 60 μm thick light diffusion control layer A. As a result, a laminate in which the process sheet, the light diffusion control layer A (thickness: 60 μm) and the release sheet were sequentially laminated was obtained.

[0111] In addition, a cross section of the formed light diffusion control layer A was observed under a microscope, and the result confirmed that a column structure in which a plurality of columns stand in the entire thickness direction was formed inside the light diffusion control layer A. That is, the ratio of the column structure region inside the obtained light diffusion control layer A extending in the thickness direction was 100%. In addition, it was confirmed that the above-mentioned columns were parallel to the thickness direction of the light diffusion control layer A (tilt angle 0°). In addition, in this specification, for this tilt angle, the vertical upward direction in the normal direction of the film surface is set to 0°, the forward direction of the conveyor belt is recorded as positive, and the opposite direction is recorded as negative.

[0112] In addition, the peak illuminance and the accumulated light amount were measured by placing a UV METER (manufactured by Eyegraphics Co., Ltd., product name "EYE UV Integrated Illuminance Meter UVPF-A1") equipped with a light receiver at the position of the coating film. The thickness of the light diffusion control layer A was measured using a constant pressure thickness meter (manufactured by Takara Seisakusho Co., Ltd., product name "TECLOCK PG-02J").

[0113] [Production Example 2] (Light Diffusion Control Layer B)

[0114] The composition for the light diffusion control layer obtained in the same manner as the process (1) of Preparation Example 1 is applied to a single side of a long polyethylene terephthalate sheet as a process sheet to form a coating film. The laminated body consisting of the coating film and the process sheet thus obtained is placed on a conveyor belt. At this time, the surface of the coating film side of the laminated body is made to be the upper side, and at the same time, the long side direction of the laminated body is made parallel to the conveying direction of the conveyor belt. Then, a UV point parallel light source (manufactured by JATEC CO., LTD.) is set to the conveyor belt on which the laminated body is placed, and the parallelism of the central light beam is controlled within ±3°. At this time, the light source is set in a manner that can irradiate parallel light with a direction of 10° tilted toward the conveying direction of the conveyor belt relative to the normal direction of the surface of the coating film side of the laminated body.

[0115] Then, the conveyor was operated to move the laminate while the peak illuminance on the coating surface was 2.00 mW / cm 2 , the accumulated light intensity is 53.13mJ / cm 2 The conditions are such that parallel light with a parallelism of less than 2° (ultraviolet light from a high-pressure mercury lamp with a main peak wavelength of 365nm and additional peaks at 254nm, 303nm, and 313nm) is irradiated.

[0116] Next, a release sheet (manufactured by LINTEC CORPORATION, product name "SP-PET381130", thickness: 38 μm) obtained by subjecting one side of a polyethylene terephthalate film to a release treatment using a silicone release agent is laminated on the surface of the coating film opposite to the process sheet. The laminated body consisting of the release sheet, coating film and process sheet thus obtained is placed on a conveyor belt in the same manner as described above. Next, a point parallel light source of ultraviolet rays is set on the conveyor belt in the same manner as described above. Then, the conveyor belt is operated to move the laminated body while the peak illumination on the coating film surface is 11.0 mW / cm 2 , the accumulated light intensity is 32.0mJ / cm 2 conditions, irradiate with scattered light.

[0117] In the above manner, the coating film in the laminate was cured to form a 90 μm-thick light diffusion control layer B. As a result, a laminate in which the process sheet, the light diffusion control layer B (thickness: 90 μm) and the release sheet were laminated in this order was obtained.

[0118] The ratio of the columnar structure region extending in the thickness direction of the obtained light diffusion control layer B was 10%. In addition, it was confirmed that the columnar structure was inclined by about 7° (inclination angle +7°) relative to the thickness direction of the light diffusion control layer B toward the conveyor's advancing direction.

[0119] [Production Example 3] (Light Diffusion Control Layer C)

[0120] A laminated body in which the process sheet, the light diffusion controlling layer C (thickness: 120 μm) and the release sheet were sequentially laminated was obtained in the same manner as in Production Example 2 except that the thickness of the light diffusion controlling layer to be formed was changed to 120 μm.

[0121] In addition, the ratio of the columnar structure region extending in the thickness direction inside the obtained light diffusion control layer C was 30%.

[0122] [Production Example 4] (Light Diffusion Control Layer D)

[0123] A laminated body in which the process sheet, the light diffusion controlling layer D (thickness: 140 μm) and the release sheet were sequentially laminated was obtained in the same manner as in Production Example 2 except that the thickness of the light diffusion controlling layer to be formed was changed to 140 μm.

[0124] In addition, the ratio of the columnar structure region extending in the thickness direction inside the obtained light diffusion control layer D was 40%.

[0125] [Production Example 5] (Light Diffusion Control Layer E)

[0126] A laminated body in which the process sheet, the light diffusion controlling layer E (thickness: 160 μm) and the release sheet were sequentially laminated was obtained in the same manner as in Production Example 2 except that the thickness of the light diffusion controlling layer to be formed was changed to 160 μm.

[0127] In addition, the ratio of the columnar structure region extending in the thickness direction inside the obtained light diffusion control layer E was 50%.

[0128] [Production Example 6] (Light Diffusion Control Layer F)

[0129] A laminated body in which the process sheet, the light diffusion controlling layer F (thickness: 185 μm) and the release sheet were sequentially laminated was obtained in the same manner as in Production Example 2 except that the thickness of the light diffusion controlling layer to be formed was changed to 185 μm.

[0130] In addition, the ratio of the columnar structure region extending in the thickness direction inside the obtained light diffusion control layer F was 60%.

[0131] [Example 1]

[0132] The process sheet and the release sheet were peeled off from the laminated bodies prepared in Preparation Example 1 and Preparation Example 4, respectively, to obtain the light diffusion control layer A and the light diffusion control layer D. Then, the surface of the light diffusion control layer D as the second light diffusion control layer opposite to the surface irradiated with ultraviolet rays was laminated on the surface side of the light diffusion control layer A as the first light diffusion control layer irradiated with ultraviolet rays so that the long side directions (moving direction of the conveyor belt) of each other were aligned, thereby obtaining a light diffusion control body.

[0133] Furthermore, the surface on the first light diffusion control layer (light diffusion control layer A) side of the above-mentioned light diffusion control body is stacked with the reflective surface of a reflective plate (a reflective plate made by vapor-depositing aluminum on the surface of a polyethylene terephthalate film with a thickness of 100 μm in a manner to have a thickness of 300 nm) to obtain a reflective display sample.

[0134] [Example 2]

[0135] A light diffusion control body and a reflective display body sample were obtained in the same manner as in Example 1 except that the process sheet and the release sheet were peeled off from the laminated body prepared in Preparation Example 5 to obtain a light diffusion control layer E and used as the second light diffusion control layer.

[0136] [Example 3]

[0137] A light diffusion control body and a reflective display body sample were obtained in the same manner as in Example 1 except that the process sheet and the release sheet were peeled off from the laminated body prepared in Preparation Example 6 to obtain a light diffusion control layer F and used as the second light diffusion control layer.

[0138] [Comparative Example 1]

[0139] The second light diffusion control layer was not provided, and the single-layer first light diffusion control layer (light diffusion control layer A) was used as the light diffusion control body. Further, a reflective display body sample was obtained in the same manner as in Example 1 except that this light diffusion control body was used.

[0140] [Comparative Example 2]

[0141] A light diffusion control body and a reflective display body sample were obtained in the same manner as in Example 1 except that the process sheet and the release sheet were peeled off from the laminated body prepared in Preparation Example 2 to obtain a light diffusion control layer B and used it as the second light diffusion control layer.

[0142] [Comparative Example 3]

[0143] A light diffusion control body and a reflective display body sample were obtained in the same manner as in Example 1 except that the process sheet and the release sheet were peeled off from the laminated body prepared in Preparation Example 3 to obtain a light diffusion control layer C and used it as the second light diffusion control layer.

[0144] [Test Example 1] (Measurement of the variable angle haze of the light diffusion control layer)

[0145] The haze value (%) of the light diffusion control layers A to F produced in Production Examples 1 to 6 was measured using a variable angle haze meter (manufactured by Toyo Seiki Seisaku-sho, Ltd., product name “Haze-Gard Plus, variable angle haze meter”).

[0146] Specifically, the surface of the light diffusion control layer monomer obtained by peeling off the process sheet and the peeling sheet from the laminate obtained in Examples 1 to 6, which is opposite to the surface irradiated with ultraviolet rays during manufacturing, is attached to a single surface of an alkali-free glass plate (thickness: 1.1 mm) to obtain a laminate. Then, the laminate is arranged in such a manner that the distance from the opening of the integrating sphere in the above-mentioned variable angle haze meter to the arrival position of the measurement light is 62 mm, and the alkali-free glass side is opposite to the light source. Next, the light diffusion control layer is rotated in the long side direction (the conveying direction during production) with the width direction of the light diffusion control layer at the above-mentioned arrival position as the rotation axis, thereby measuring the change in the haze value (%). That is, by changing only the inclination angle of the light diffusion control layer, the incident angle of the measurement light relative to the light diffusion control layer is changed, and the haze value (%) is measured for each incident angle. The incident angle of the measuring light in the normal direction of the laminate was set to 0°, and the rotation direction of the light diffusion control layer in the forward direction (the conveying direction during production) close to the light source was set to positive, and the measurement was performed in the range of -70° to 70°. The details of the measurement conditions are as follows.

[0147] Light source: C light source

[0148] Measuring diameter:

[0149] Integrating sphere opening diameter:

[0150] The results of the measurement are shown in Figure 4 .in addition, Figure 4 The horizontal axis is the incident angle and the vertical axis is the measured value. In addition, the value when the incident angle is 0°, the minimum value and the maximum value of the measured haze value (%) were determined. These results are shown in Table 1.

[0151] In addition, according to Figure 4 The diffusion center axis of the light diffusion control layer is determined as follows. Figure 4 In the graph, when the incident angle changes from a negative value to a positive value, the haze value rises and then decreases to the original level again. Here, the average of the incident angle at which the haze value first becomes the largest when it rises and the incident angle at which the haze value becomes the largest immediately before the haze value decreases to the original level is calculated and used as the diffusion center axis. In addition, Figure 4 In the graph of , although there are two incident angles at which the haze value becomes maximum, and there is one incident angle between them at which the haze value becomes minimum, the incident angle at which the haze value becomes minimum is not considered when determining the diffusion center axis. The diffusion center axis obtained in this way is also shown in Table 1.

[0152] [Test Example 2] (Measurement of diffusion brightness distribution of light diffusion control layer)

[0153] The diffuse brightness distribution of the light diffusion control layers A to F produced in Production Examples 1 to 6 was measured using a diffuse brightness distribution measuring device (manufactured by Suga Test Instruments Co., Ltd., product name: Variable Angle Colorimeter VC-2).

[0154] Specifically, the surface of the light diffusion control layer monomer obtained by peeling off the process sheet and the release sheet from the laminate obtained in Preparation Examples 1 to 6, which is opposite to the surface irradiated with ultraviolet rays during manufacturing, is attached to a single surface of an alkali-free glass plate (thickness: 1.1 mm) to obtain a laminate. The surface on the alkali-free glass side of the laminate is irradiated with measuring light from the direction of the diffusion center axis, and the light intensity of the diffused light transmitted to the other surface (the surface on the light diffusion control layer side) is measured in sequence while the light receiver is moved. At this time, the light diffusion control layer including the emission point of the diffused light is rotated with the width direction (vertical direction in the same plane as the long side direction) as the axis, and the light receiver is moved relative to the surface of the light diffusion control layer while maintaining the same distance from the emission point. Regarding this movement, the angle (light receiver angle) between the line segment connecting the emission point and the light receiver and the normal passing through the emission point is -45° to 45°. The angle values ​​are expressed as positive angles when the light receiver is near the longitudinal direction of the light diffusion control layer (the conveying direction during production) and negative angles when the light receiver is far.

[0155] On the other hand, as a reference, the reference value of light intensity was measured without setting the measurement object and fixing the light receiver angle to 0° (the state in which the measurement light is directly irradiated to the light receiver). Then, the ratio of the light intensity of each light diffusion control layer measured as described above to the reference value was calculated (the percentage of the above reference value being 100%). The results are shown in Figure 5-1 and Figure 5-2 .in addition, Figure 5-1 and Figure 5-2 The horizontal axis is the light receiver angle and the vertical axis is the light intensity (%). Figure 5-1 The results of light diffusion control layers A, D, E and F are shown in FIG. Figure 5-2 The results of light diffusion control layers B and C are shown in FIG.

[0156] The maximum value of the obtained light intensity (%) was determined. The maximum value is shown in Table 1. Furthermore, the ratio of the maximum values ​​of the light diffusion control layers A to F based on the maximum value of the light diffusion control layer A was calculated. The results are also shown in Table 1.

[0157] [Test Example 3] (Measurement of diffuse brightness distribution of reflective display sample)

[0158] The diffuse brightness distribution of the reflective display samples having the light diffusion controller obtained in Examples and Comparative Examples was measured using a diffuse brightness distribution measuring device (manufactured by Suga Test Instruments Co., Ltd., product name “Variable Angle Colorimeter VC-2”).

[0159] Specifically, for the surface on the light diffusion control body side of the reflective display body sample, light is irradiated at an incident angle of 10° (incident angle 10°) with the normal line of the surface, and the light intensity of the diffused light generated by reflection in the reflective display body sample is measured in sequence while the light receiver is moved. At this time, the light receiver is moved relative to the light diffusion control layer while maintaining the same distance from the emission point in a manner of rotating the width direction of the light diffusion control layer containing the emission point of the diffused light (the vertical direction in the same plane as the long side direction) as the axis. Regarding this movement, the angle (light receiver angle) between the line segment connecting the emission point and the light receiver and the normal line passing through the emission point is -45° to 0°. In addition, the value of the angle is expressed in a manner that the angle of the light receiver in the near position is positive and the angle in the far position is negative relative to the forward direction side of the long side direction of the light diffusion control layer (the conveying direction during production). In addition, as a light source, a C light source is used.

[0160] On the other hand, as a reference, a standard white plate was set as a measurement object, and the light receiving angle was fixed at -45°, and the reference value of the light intensity was measured. Then, the ratio of the light intensity of each light reflective display sample measured as described above to the reference value was calculated (the percentage of the reference value being 100%). The results are shown in Figure 6-1 .in addition, Figure 6-1 The horizontal axis is the light receiving angle, and the vertical axis is the light intensity (%). In addition, Table 2 shows the light intensity (%) when the light receiving angle is 0°.

[0161] Furthermore, the incident angle was changed to 20° (light receiver angle: -45° to 10°), 30° (light receiver angle: -45° to 20°), and 40° (light receiver angle: -45° to 30°), and the diffuse brightness distribution was measured in the same manner as above. The measurement results are shown in Figure 6-2 , Figure 6-3 and Figure 6-4 In addition, Table 2 also shows the light intensity (%) when the light receiving angle is 0° for each case where the incident angle is changed to 20°, 30°, and 40°.

[0162] In addition, based on the light intensity (%) obtained in the above manner when the light receiving angle is 0°, a graph is prepared to show the relationship between the minimum value (%) of the variable angle haze value and the light intensity (%) for each incident angle. Figure 7In this chart, the minimum value (%) of the variable angle haze value of the second light diffusion control layer of each example is used as the horizontal axis, and the light intensity (%) when the light receiver angle is 0° is used as the vertical axis. In addition, for Comparative Example 1 in which the second light diffusion control layer is not provided, the minimum value (%) of the variable angle haze value of the second light diffusion control layer is set to "0%". In addition, points with the same incident angle are connected to each other with line segments.

[0163] [Test Example 4] (Evaluation of Visibility of Reflective Display Sample)

[0164] The reflective display samples manufactured in Example 1, Example 2 and Comparative Example 3 are arranged on a support table in such a manner that the surface on the light diffusion control body side is on the upper side. Then, the light from a desk lamp is irradiated to the surface at an incident angle of 10° with respect to the normal line of the surface (incident angle 10°). Then, the brightness of the reflective display sample is observed with the naked eye from a position that is in front of the surface, and at the same time, the reflective display sample is photographed with a digital camera from the same position. The resulting image is shown in Figure 8 In addition, the incident angle was changed to 35°, and the image was confirmed with the naked eye in the same manner as above, while being photographed with a digital camera. The obtained image is shown in Figure 8 .

[0165] according to Figure 8 It can be seen that when the incident angle is 10°, the reflective display samples of Example 1, Example 2, and Comparative Example 3 can be identified roughly equally brightly. On the other hand, when the incident angle is 35°, the reflective display samples of Example 1 and Example 2 can be identified brightly, but the reflective display sample of Comparative Example 3 is dim and cannot be identified.

[0166] [Table 1]

[0167]

[0168] [Table 2]

[0169]

[0170] As shown in Table 2, it can be seen that the reflective display sample with the light diffusion control body of the embodiment can reflect light to the front direction with sufficient light intensity when the incident angle is 10° to 30°. In particular, it can be seen that when the incident angle is 30°, the light intensity of the reflective display sample of the comparative example is close to 100% or a value smaller than 100%, while the reflective display sample of the embodiment can reflect light to the front direction with a light intensity far greater than 100%. These results are consistent with Figure 8 The results of the evaluation based on naked eye visibility are consistent.

[0171] Furthermore, it can be seen that when the incident angle is 40°, the reflective display samples of the comparative example cannot reflect light in the front direction, whereas the reflective display samples of Examples 2 and 3 can reflect light in the front direction.

[0172] In addition, according to Figure 8 It can be seen from the graph that when the incident angle is 10° and 20°, no matter what the minimum value of the variable angle haze value of the second light diffusion control layer is, it can reflect light with a light intensity of more than 100%. When the incident angle is 30°, when the minimum value of the variable angle haze value of the second light diffusion control layer is about 35% or more, it can reflect light with a light intensity of more than 100%.

[0173] Industrial Applicability

[0174] The light diffusion controller of the present invention is suitable for use in the production of displays, particularly reflective displays.

Claims

1. A light diffusion control body comprising at least two light diffusion control layers, wherein the light diffusion control layers have a regular internal structure having a plurality of relatively high refractive index regions in a relatively low refractive index region, At least two of the light diffusion control layers are stacked on top of each other, When the normal direction of each of the first light diffusion control layer and the second light diffusion control layer, which are two layers of the light diffusion control layer, is set to 0° and light is sequentially irradiated at an incident angle of -70° to 70°, the minimum haze value measured is 35% or more, The difference in haze value between the first light diffusion control layer and the second light diffusion control layer is 5 percentage points or less, and the haze value in the difference in haze value is the haze value measured when light is irradiated to each light diffusion control layer at an incident angle of 0°. An angle formed by a diffusion central axis of the first light diffusion control layer and a diffusion central axis of the second light diffusion control layer is greater than or equal to 5° and less than or equal to 20°.

2. The light diffusion control body according to claim 1, characterized in that: A diffusion center axis of the first light diffusion control layer and a diffusion center axis of the second light diffusion control layer have different angles.

3. The light diffusion control body according to claim 1 or 2, characterized in that: The regular internal structure in at least one of the first light diffusion control layer and the second light diffusion control layer is a columnar structure in which a plurality of relatively high refractive index columns stand in a row in the relatively low refractive index region along a film thickness direction of the film.

4. A reflective display, characterized in that: It has: The light diffusion controller according to any one of claims 1 to 3; and A reflective plate is provided on one side of the light diffusion control body.

Images