Display body

Abstract

Provided is a display body 1 comprising a light scattering layer 11, at least one light diffusion control layer 12 that is laminated on one surface side of the light scattering layer 11 and has a regular internal structure provided with a plurality of regions having a relatively high refractive index within a region having a relatively low refractive index, and a display device 13 laminated on a surface side of the light diffusion control layer 12 opposite the light scattering layer 11. At a position 0.3 cm from a display surface, the ratio (maximum inclination / 0° luminance) of the maximum value of inclination (maximum inclination) of luminance to angles in a luminance distribution measured in a range of −70° to 70°, where 0° indicates a direction perpendicular to the display surface, to the luminance of light emitted in the direction perpendicular to the display surface (front direction) is 0.030 or lower. In the display body 1, the change in luminance resulting from the difference of the recognized angle is excellently uniformized.

Description

display body

[0001] The present invention relates to a display.

[0002] BACKGROUND ART In recent years, displays, such as televisions, PC monitors, digital signage, smartphones, and tablet terminals, generally include display devices such as liquid crystal display devices and organic electroluminescence (organic EL) devices.

[0003] The above-mentioned display devices usually tend to have lower brightness when viewed from an oblique direction than when viewed from the front (direction perpendicular to the display surface).

[0004] In order to equalize the difference in brightness due to the difference in viewing angle, a display using an optical element that can control the diffusion and transmission of light depending on the angle of incidence of the light has been studied (for example, Patent Document 1). In this display, the optical element is laminated on the display surface of the display device, and the optical element diffuses the light from the display device in oblique directions, so that the viewer can view the displayed content at a predetermined brightness even when viewing from an oblique direction.

[0005] JP 2014-115421 A

[0006] However, the display disclosed in Patent Document 1 suffers from a problem that brightness drops significantly at a certain angle when the viewing angle of the display surface is gradually changed from a frontal direction to an oblique direction, and in this respect, the display disclosed in Patent Document 1 does not sufficiently uniformize the change in brightness due to differences in viewing angle.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a display device in which the change in luminance due to differences in viewing angle is well-uniformed.

[0008] In order to achieve the above object, first, the present invention provides a display device comprising: a light-scattering layer; at least one light diffusion control layer laminated on one side of the light-scattering layer and having a regular internal structure with a plurality of regions with a relatively high refractive index within a region with a relatively low refractive index; and a display device laminated on the side of the light diffusion control layer opposite the light-scattering layer, wherein the ratio (maximum slope) of the maximum value of the slope with respect to the angle of luminance in a luminance distribution measured at a position 0.3 cm from the display surface in a range of -70° to 70°, with the direction perpendicular to the display surface being 0°, to the luminance of light emitted in the direction perpendicular to the display surface (front direction) (maximum slope / 0° luminance) is 0.030 or less (Invention 1).

[0009] In the above invention (Invention 1), the regular internal structure is preferably a louver structure in which a plurality of plate-like regions with different refractive indices are alternately arranged in any direction along the sheet surface (Invention 2).

[0010] In the above invention (invention 2), it is preferable that the direction perpendicular to the longitudinal direction of the plate-like region is inclined with respect to the thickness direction of the light diffusion control layer (invention 3).

[0011] In the above invention (Invention 3), it is preferable that the display body has two or more layers of the light diffusion control layer, and the direction of inclination of the plate-shaped region is different among the multiple light diffusion control layers (Invention 4).

[0012] In the above inventions (Inventions 1 to 4), the light-scattering layer preferably contains light-diffusing fine particles (Invention 5).

[0013] The display according to the present invention exhibits excellent uniformity in the change in luminance due to differences in viewing angle.

[0014] It is a cross-sectional view showing a display body according to one embodiment of the present invention. It is a cross-sectional view showing another example of a display body according to one embodiment of the present invention. It is a graph showing the relationship between the viewing angle and the luminance for various display bodies. It is a perspective view showing a schematic internal structure of the light diffusion control layer in the present invention.

[0015] An embodiment of the present invention will now be described. Fig. 1 shows a cross-sectional view of an example of a display according to one embodiment of the present invention. The display 1 according to this embodiment includes a light-scattering layer 11, at least one light diffusion control layer 12 laminated on one side of the light-scattering layer 11 and having a regular internal structure with a plurality of regions with a relatively high refractive index within a region with a relatively low refractive index, and a display device 13 laminated on the side of the light diffusion control layer 12 opposite the light-scattering layer 11.

[0016] Furthermore, in the display 1 according to this embodiment, at a position 0.3 cm from the display surface, in the luminance distribution measured in the range of -70° to 70°, with the direction perpendicular to the display surface being 0°, the ratio (maximum slope) of the maximum value of the slope with respect to the angle of luminance (maximum slope) to the luminance of light emitted in the direction perpendicular to the display surface (front direction) is 0.030 or less.

[0017] As described above, the display body 1 according to this embodiment includes at least one light diffusion control layer 12. Fig. 1 shows a display body 1 including one light diffusion control layer 12. On the other hand, Fig. 2 shows a display body 1' including two light diffusion control layers (a light diffusion control layer 12a and a light diffusion control layer 12b). When the display body 1 includes two or more light diffusion control layers, all of the light diffusion control layers are disposed between the light scattering layer 11 and the display device 13, as shown in Fig. 2.

[0018] The display 1 according to this embodiment can be viewed with sufficient brightness even when the display surface is viewed from an oblique direction, and can be viewed without noticing a sudden change in brightness when the viewing angle is changed from the front to an oblique direction. The reasons for this effect are thought to be as follows, but are not limited to the following.

[0019] 3 is a graph showing the relationship between the viewing angle (horizontal axis) and the luminance (vertical axis) when the display is viewed from various viewing angles. Here, the viewing angle on the horizontal axis represents the angle between the display surface and a line segment connecting the viewer (or measuring device) to an arbitrary point on the display surface. Furthermore, the luminance on the vertical axis is shown as a ratio to the luminance when viewed from a viewing angle of 0° (front).

[0020] 3 shows graphs of three types of display bodies, A to C. Of these, the display body shown by A is a display body consisting only of a display device, without any special optical elements such as a light scattering layer or a light diffusion control layer. The display body shown by B is a display body in which only a light diffusion control layer is laminated on a display device, as exists in prior art. The display body shown by C corresponds to the display bodies 1 and 1' according to this embodiment, and is formed by laminating a light scattering layer and a light diffusion control layer on a display device.

[0021] In display A, the brightness gradually decreases as the viewing angle changes from the front (0°) to an oblique direction, and at around ±60°, the brightness is less than 40% of that at around the front (0°). On the other hand, in display B, light emitted from the display device in a predetermined direction (particularly an oblique direction) is moderately diffused by the light diffusion control layer. As a result, in display B, the brightness at around ±60° is maintained at about 50% of that at around the front (0°). In other words, when viewed from an oblique direction (particularly in the range of 45° to 70° and -45° to -70°), display B is visible brighter than display A.

[0022] However, it can be seen that for display body B, a sudden change in luminance occurs in response to a change in viewing angle between approximately 10° and 20° and between approximately -10° and -20° (ranges surrounded by dashed lines). That is, for display body B, when the viewing angle is changed from the front direction to an oblique direction, the brightness suddenly decreases.

[0023] On the other hand, in display C, which corresponds to the display according to this embodiment, the decrease in brightness when viewed from an oblique direction is significantly suppressed, and there is no sudden decrease in brightness as seen in display B. This is thought to be the result of a combination of the effect of the light diffusion control layer in display C, which improves brightness when viewed from an oblique direction, and the effect of the light scattering layer (which scatters light overall), which alleviates sudden changes in brightness. In this way, the display according to this embodiment exhibits well-uniform changes in brightness due to differences in viewing angle.

[0024] Furthermore, as described above, in the display 1 according to this embodiment, even if the maximum tilt / 0° luminance is 0.030 or less, a display with uniform luminance is possible. From this viewpoint, the maximum tilt / 0° luminance is preferably 0.029 or less, and particularly preferably 0.028 or less. The lower limit of the maximum tilt / 0° luminance is not particularly limited, and is preferably, for example, 0.001 or more, particularly preferably 0.005 or more, and even more preferably 0.01 or more. Details of the method for measuring the maximum tilt / 0° luminance are as described in the test examples below.

[0025] 1. Light-Scattering Layer The light-scattering layer 11 in this embodiment is not particularly limited in structure or composition as long as it is a layer having light-diffusing properties. From the viewpoint of easily achieving the desired light-diffusing properties and facilitating the production of the display body 1, the light-scattering layer 11 is preferably a layer containing light-diffusing fine particles, and more preferably a pressure-sensitive adhesive layer containing light-diffusing fine particles.

[0026] The adhesive constituting the adhesive layer is not particularly limited as long as it does not interfere with the light diffusion effect of the light-diffusing microparticles, and is preferably transparent. It is also preferable that the adhesive exhibits sufficient adhesive strength to maintain the layer structure of the display body 1. Specific examples of the adhesive include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives. Among these, it is preferable to use acrylic adhesives because they can easily exhibit the desired performance.

[0027] When the light-scattering layer 11 is a pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive, the pressure-sensitive adhesive layer is preferably formed from a pressure-sensitive adhesive composition containing at least light-diffusing fine particles, an acrylic polymer, and a crosslinking agent.

[0028] (1) Light-diffusing fine particles The light-diffusing fine particles are not particularly limited, but preferred examples include inorganic fine particles, organic fine particles, silicone fine particles made of silicon-containing compounds having an intermediate structure between inorganic and organic, such as silicone resins (for example, the Tospearl series manufactured by Momentive Performance Materials Japan Co., Ltd.), hybrid fine particles of organic resins and silicone resins, etc. The light-diffusing fine particles may be used alone or in combination of two or more types.

[0029] Examples of inorganic fine particles include fine particles made of metal oxides such as silica, aluminum oxide, zirconium oxide, titanium oxide, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, and cerium oxide; and metal fluorides such as magnesium fluoride and sodium fluoride. Among these, metal oxides are preferred, with titanium oxide or zinc oxide being particularly preferred, and titanium oxide being even more preferred. The surfaces of the inorganic fine particles may be chemically modified with an organic compound or the like.

[0030] The shape of the inorganic fine particles may be either regular, such as spherical, or irregular, but irregular shapes are preferred from the viewpoint of efficiently exhibiting light diffusing properties with a small amount.

[0031] The inorganic fine particles in this embodiment are preferably so-called nanoparticles. Specifically, the average particle size of the inorganic fine particles is preferably 10 to 1000 nm, more preferably 30 to 700 nm, and particularly preferably 50 to 500 nm. This makes it easier to achieve the desired light diffusion properties and more easily suppress sudden changes in brightness. The average particle size of the inorganic fine particles is measured by a laser diffraction / scattering method.

[0032] In this embodiment, the refractive index of the inorganic fine particles is preferably 1.8 to 3, more preferably 2 to 2.8, and even more preferably 2.5 to 2.7. This makes it easier to achieve the desired light diffusion properties and more easily suppress sudden changes in brightness. The refractive index of the light-diffusing fine particles can be measured, for example, by the following method. That is, the fine particles are placed on a slide glass, a refractive index standard solution is dropped onto the fine particles, and the sample is covered with a cover glass to prepare a sample. The sample is observed under a microscope, and the refractive index of the refractive index standard solution at which the outline of the fine particles is most difficult to see is taken as the refractive index of the fine particles.

[0033] Preferred examples of organic fine particles include acrylic resin, polystyrene resin, polyethylene resin, epoxy resin, copolymers or mixtures thereof, and the like.

[0034] The shape of the organic fine particles, silicone fine particles, and hybrid fine particles is preferably spherical, which allows for uniform light diffusion. The average particle size of these fine particles, as measured by the centrifugal sedimentation light transmission method, is preferably 0.1 to 20 μm, more preferably 1 to 15 μm, particularly preferably 2 to 12 μm, even more preferably 3 to 10 μm, and most preferably 4 to 7 μm. This makes it easier to achieve the desired light diffusion properties and more easily suppress sudden changes in brightness.

[0035] The average particle size measured by the centrifugal sedimentation light transmission method was measured using a centrifugal automatic particle size distribution analyzer (CAPA-700, manufactured by Horiba, Ltd.) using a measurement sample prepared by thoroughly stirring 1.2 g of fine particles and 98.8 g of isopropyl alcohol.

[0036] The refractive index of the organic fine particles, silicone fine particles, and hybrid fine particles in this embodiment is preferably 1.2 to 3, more preferably 1.3 to 2.5, particularly preferably 1.35 to 2, even more preferably 1.4 to 1.7, and most preferably 1.42 to 1.55, which makes it easier to achieve the desired light diffusion properties and more easily suppress abrupt changes in brightness.

[0037] When the pressure-sensitive adhesive composition contains light-diffusing microparticles and an acrylic polymer, the content of the light-diffusing microparticles in the pressure-sensitive adhesive composition is preferably 0.1 to 50 parts by mass, more preferably 1 to 35 parts by mass, particularly preferably 2 to 30 parts by mass, even more preferably 4 to 24 parts by mass, and even more preferably 7 to 18 parts by mass, most preferably 10 to 15 parts by mass, per 100 parts by mass of the acrylic polymer. This makes it easier to achieve the desired light diffusion properties and more easily suppress sudden changes in brightness. As a result, the display 1 according to this embodiment has better visibility.

[0038] (2) Acrylic Polymer The monomer units constituting the acrylic polymer can be appropriately adjusted from the viewpoints of transparency, adhesive strength, etc., but it is particularly preferable that the acrylic polymer contains a (meth)acrylic acid alkyl ester and a monomer having a reactive functional group in the molecule (a reactive functional group-containing monomer). In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the term "polymer" also includes the concept of "copolymer."

[0039] The acrylic polymer can exhibit desirable adhesiveness by containing a (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer. As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is preferred. The alkyl group may be linear or branched, or may have a cyclic structure.

[0040] Examples of (meth)acrylic acid alkyl esters having an alkyl group containing 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate. Among these, from the viewpoints of the dispersibility of the light-diffusing fine particles and the ease with which the resulting light-scattering layer achieves the desired light diffusion properties, methyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred. These may be used alone or in combination of two or more.

[0041] The acrylic polymer preferably contains 20 to 95 mass % of (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer, more preferably 40 to 90 mass %, and even more preferably 60 to 85 mass %. Within these ranges, it becomes easier to achieve the desired adhesive strength.

[0042] The acrylic polymer contains a reactive functional group-containing monomer as a monomer unit constituting the polymer, and reacts with a crosslinking agent described below via the reactive functional group derived from the reactive functional group-containing monomer, thereby forming a crosslinked structure (three-dimensional network structure), and a pressure-sensitive adhesive having the desired cohesive strength is obtained.

[0043] Preferred examples of the reactive functional group-containing monomer include a monomer having a hydroxy group in the molecule (hydroxy group-containing monomer), a monomer having a carboxy group in the molecule (carboxy group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), etc. These reactive functional group-containing monomers may be used alone or in combination of two or more.

[0044] Among the above-mentioned reactive functional group-containing monomers, hydroxy group-containing monomers or carboxy group-containing monomers are preferred from the viewpoint of easily adjusting the crosslink density and easily obtaining an adhesive having the desired cohesive strength, and from the viewpoint of easily achieving good dispersibility of the aforementioned light-diffusing microparticles, and from the viewpoint of adhesive strength, it is preferable to use a combination of a hydroxy group-containing monomer and a carboxy group-containing monomer.

[0045] Examples of hydroxy group-containing monomers include (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among the above, (meth)acrylic acid hydroxyalkyl esters having a hydroxyalkyl group having 1 to 4 carbon atoms are preferred. Specifically, for example, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, with 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate being particularly preferred. These may be used alone or in combination of two or more.

[0046] Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid and methacrylic acid are preferred from the viewpoint of the cohesive strength of the resulting (meth)acrylic acid ester polymer (A). These may be used alone or in combination of two or more.

[0047] The acrylic polymer preferably contains 0.1 to 20% by mass, more preferably 0.5 to 15% by mass, and particularly preferably 0.4 to 10% by mass of reactive functional group-containing monomers as monomer units constituting the polymer. Within these ranges, the acrylic polymer is more likely to undergo the desired crosslinking reaction with the crosslinking agent, and as a result, the resulting pressure-sensitive adhesive is more likely to have good cohesive strength. Furthermore, the dispersibility of the light-diffusing fine particles described above is more likely to be good, and the resulting light-scattering layer is more likely to achieve the desired light diffusion properties.

[0048] The acrylic polymer of this embodiment may further contain other monomers as monomers constituting the polymer. Examples of such other monomers include alicyclic structure-containing (meth)acrylic acid esters such as dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate; (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; non-crosslinkable acrylamides such as acrylamide and methacrylamide; non-crosslinkable (meth)acrylic acid esters having a tertiary amino group such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate; vinyl acetate; and styrene. Among these, vinyl acetate is preferred from the viewpoint of the cohesive strength of the resulting (meth)acrylic acid ester polymer (A). These may be used alone or in combination of two or more.

[0049] The acrylic polymer preferably contains 1 to 30% by mass, particularly 10 to 25% by mass, and even more preferably 15 to 20% by mass, of other monomers as monomer units constituting the polymer. This makes it easier for the resulting pressure-sensitive adhesive to have good cohesive strength. Furthermore, the dispersibility of the light-diffusing fine particles described above is also likely to be good, making it easier for the resulting light-scattering layer to achieve the desired light diffusion properties.

[0050] The polymerization mode of the acrylic polymer in this embodiment may be a random polymer or a block polymer. The acrylic polymer can be obtained by polymerizing the above-mentioned monomers by a conventional method. For example, the acrylic polymer can be prepared by polymerization using an emulsion polymerization method, a solution polymerization method, a suspension polymerization method, a bulk polymerization method, an aqueous solution polymerization method, or the like. Among these, from the viewpoints of stability during polymerization and ease of handling during use, the acrylic polymer is preferably prepared by a solution polymerization method carried out in an organic solvent.

[0051] The weight-average molecular weight of the acrylic polymer is preferably 100,000 to 5,000,000, more preferably 200,000 to 2,000,000, particularly preferably 500,000 to 1,500,000, and even more preferably 700,000 to 1,000,000. This improves the dispersibility of the light-diffusing fine particles in the acrylic polymer, making it easier for the resulting pressure-sensitive adhesive to exhibit the desired adhesive and optical performance. The weight-average molecular weight measured in this specification refers to a value calculated in terms of standard polystyrene, measured by gel permeation chromatography (GPC).

[0052] The pressure-sensitive adhesive composition according to the present embodiment may contain one or more of the above-mentioned acrylic polymers. Furthermore, the pressure-sensitive adhesive composition according to the present embodiment may contain another acrylic polymer together with the above-mentioned acrylic polymer.

[0053] (3) Crosslinking Agent The crosslinking agent crosslinks the acrylic polymer by heating the pressure-sensitive adhesive composition, thereby enabling the formation of a favorable three-dimensional network structure, thereby further improving the cohesive strength of the resulting pressure-sensitive adhesive.

[0054] Examples of the crosslinking agent are preferably those that react with the reactive functional groups of the acrylic polymer, and examples thereof include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based crosslinking agents.

[0055] Among the examples of crosslinking agents mentioned above, when the reactive group of the acrylic polymer is a hydroxy group, it is preferable to use an isocyanate-based crosslinking agent that has excellent reactivity with the hydroxy group. Also, when the reactive group of the acrylic polymer is a carboxy group, it is preferable to use an epoxy-based crosslinking agent that has excellent reactivity with the carboxy group. The crosslinking agents can be used alone or in combination of two or more.

[0056] The isocyanate-based crosslinking agent contains at least a polyisocyanate compound, such as aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and biuret and isocyanurate forms thereof, as well as adducts thereof that are reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, from the viewpoint of reactivity with hydroxy groups, it is preferable to use a trimethylolpropane-modified aromatic polyisocyanate, in particular at least one of trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate, and from the viewpoint of weather resistance, it is preferable to use an aliphatic polyisocyanate such as hexamethylene diisocyanate.

[0057] Examples of epoxy crosslinking agents include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidylamine, etc. Among these, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is preferred from the viewpoint of reactivity with carboxy groups.

[0058] When the pressure-sensitive adhesive composition contains a crosslinking agent and an acrylic polymer, the content of the crosslinking agent in the pressure-sensitive adhesive composition is preferably 0.01 to 5 parts by mass, particularly preferably 0.1 to 2 parts by mass, and even more preferably 0.2 to 1 part by mass, per 100 parts by mass of the acrylic polymer. By having the content of the crosslinking agent in the above range, the resulting pressure-sensitive adhesive will exhibit superior cohesive strength.

[0059] (4) Various Additives If desired, the pressure-sensitive adhesive composition may contain various additives commonly used in acrylic pressure-sensitive adhesives, such as a silane coupling agent, an anti-rust agent, an ultraviolet absorber, a tackifier, an antioxidant, a light stabilizer, a softener, a refractive index adjuster, etc. It should be noted that polymerization solvents and dilution solvents, which will be described later, are not included in the additives that constitute the pressure-sensitive adhesive composition.

[0060] (5) Method for preparing pressure-sensitive adhesive composition The pressure-sensitive adhesive composition can be prepared by preparing an acrylic polymer, mixing the obtained acrylic polymer with light-diffusing fine particles and a crosslinking agent, and adding additives, etc., as desired.

[0061] The acrylic polymer can be prepared by polymerizing a mixture of monomers constituting the polymer using a conventional radical polymerization method. The polymerization of the acrylic polymer is preferably carried out by a solution polymerization method using a polymerization initiator as desired. However, the polymerization is not limited to this, and the polymerization may be carried out without a solvent. Examples of polymerization solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.

[0062] After the acrylic polymer is obtained, the light-diffusing particles and the crosslinking agent, and optionally a dilution solvent and additives, etc., are added to the acrylic polymer solution and thoroughly mixed to obtain a solvent-diluted pressure-sensitive adhesive composition (coating solution). Note that when any of the above components is used in a solid state or when precipitation occurs when mixed with other components in an undiluted state, that component may be dissolved or diluted alone in a dilution solvent before being mixed with other components.

[0063] Examples of the dilution solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve-based solvents such as ethyl cellosolve.

[0064] The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within a range that allows coating, and can be appropriately selected depending on the situation. For example, the PSA composition is diluted to a concentration of 10 to 60 mass %. Note that the addition of a dilution solvent or the like is not a necessary condition for obtaining the coating solution, and as long as the PSA composition has a viscosity that allows coating, the addition of a dilution solvent is not necessary. In this case, the PSA composition becomes a coating solution in which the polymerization solvent for the acrylic polymer is used as the dilution solvent.

[0065] (6) Physical properties, etc.

[0066] The haze value of the light-scattering layer 11 in this embodiment is preferably 20 to 100%, more preferably 40 to 95%, particularly preferably 50 to 92%, and even more preferably 60 to 90%. This makes it easier to achieve both the effect of suppressing sudden changes in luminance and excellent visibility at a high level. Note that the haze value in this specification is a value measured according to the test examples described below.

[0067] The thickness of the light-scattering layer 11 in this embodiment is preferably 1 to 200 μm, more preferably 2 to 120 μm, particularly preferably 5 to 80 μm, further preferably 10 to 50 μm, and most preferably 15 to 30 μm, which makes it easy to achieve both the effect of suppressing abrupt changes in luminance and excellent visibility at a high level.

[0068] 2. Light Diffusion Control Layer The light diffusion control layer 12 in this embodiment is not limited in terms of its specific internal structure, composition, etc., as long as it has a regular internal structure including a plurality of regions with a relatively high refractive index within a region with a relatively low refractive index.

[0069] (1) Regular Internal Structure The regular internal structure described above refers to an internal structure in which a plurality of regions with a relatively high refractive index are arranged with a predetermined regularity within a region with a relatively low refractive index. For example, when a cross section of the light diffusion control layer 12 is taken along a plane parallel to the surface of the light diffusion control layer 12, the regular internal structure refers to an internal structure in which regions with a relatively high refractive index are repeatedly arranged with a uniform pitch within a region with a relatively low refractive index along at least one direction within the cross section. The regular internal structure here is distinguished from a phase-separated structure in which one phase exists without any clear regularity within another phase, and a sea-island structure in which approximately spherical island components exist within a sea component, in that the regular internal structure is formed by regions with a relatively high refractive index extending in the thickness direction of the light diffusion control layer 12.

[0070] According to the above-described regular internal structure, incident light that is incident on the surface of the light diffusion control layer 12 within a predetermined range of incident angles can be emitted while being strongly diffused at a predetermined angle (this range of incident angles is sometimes referred to as the "incident light diffusion angle region"). On the other hand, when the incident angle is outside the above-described range of incident angles, the light can be transmitted without being diffused, or can be emitted with a weaker diffusion than that of incident light within the range of incident angles.

[0071] A specific example of the regular internal structure is a louver structure in which multiple plate-like regions with different refractive indices are alternately arranged in any one direction along the sheet surface. Figure 4 shows a perspective view schematically illustrating the louver structure within the light diffusion control layer 12. As shown in Figure 4, in the louver structure, multiple plate-like regions 201 with a relatively high refractive index are arranged in a region 202 with a relatively low refractive index. Another example of a regular internal structure is a column structure in which multiple pillars with a relatively high refractive index are arranged in a region with a relatively low refractive index in the sheet thickness direction. Of these, the regular internal structure is preferably a louver structure from the viewpoint of more easily achieving uniform brightness.

[0072] In the louver structure, it is preferable that the direction perpendicular to the longitudinal direction of the plate-like region is inclined with respect to the thickness direction of the light diffusion control layer 12. Furthermore, in the column structure, it is preferable that the pillars are inclined with respect to the thickness direction of the light diffusion control layer 12. This makes it easier to achieve uniform brightness. Furthermore, when the display body 1 according to this embodiment has two or more light diffusion control layers 12, it is preferable that the inclination directions of the plate-like region and the pillars are different among the multiple light diffusion control layers 12. In particular, when the display body 1 has two light diffusion control layers 12, it is preferable that the plate-like region and the pillars are inclined in opposite directions.

[0073] The light diffusion control layer 12 in this embodiment may have a structure other than the louver structure and column structure described above. For example, the light diffusion control layer 12 may have a regular internal structure in which the plate-shaped regions in the louver structure described above are bent partway through the thickness direction of the light diffusion control layer 12. Alternatively, the light diffusion control layer 12 may have a regular internal structure in which the columns in the column structure described above are bent partway through the thickness direction of the light diffusion control layer 12. Alternatively, the light diffusion control layer 12 may have a regular internal structure in which the louver structure, the column structure, and the bent structures described above are stacked in any combination.

[0074] (2) Composition In view of facilitating the formation of the regular internal structure described above, the composition of the light diffusion control layer 12 in this embodiment is preferably a composition obtained by curing a composition for a light diffusion control layer containing a high refractive index component and a low refractive index component having a refractive index lower than that of the high refractive index component. In particular, it is preferable that the high refractive index component and the low refractive index component each have one or two polymerizable functional groups.

[0075] (2-1) High Refractive Index Component Preferred examples of the high refractive index component include (meth)acrylic acid esters containing an aromatic ring, and particularly preferred are (meth)acrylic acid esters containing multiple aromatic rings. Examples of (meth)acrylic acid esters containing multiple aromatic rings include biphenyl (meth)acrylate, naphthyl (meth)acrylate, anthracyl (meth)acrylate, benzylphenyl (meth)acrylate, biphenyloxyalkyl (meth)acrylate, naphthyloxyalkyl (meth)acrylate, anthracyloxyalkyl (meth)acrylate, benzylphenyloxyalkyl (meth)acrylate, and the like, as well as those partially substituted with halogen, alkyl, alkoxy, alkyl halide, or the like. Among these, biphenyl (meth)acrylate is preferred from the viewpoint of ease of forming a good regular internal structure, and specifically, o-phenylphenoxyethyl acrylate, o-phenylphenoxyethoxyethyl acrylate, and the like are preferred. Note that, in this specification, "(meth)acrylic acid" refers to both acrylic acid and methacrylic acid. The same applies to other similar terms.

[0076] The (weight average) molecular weight of the high refractive index component is preferably 150 to 2500, particularly preferably 200 to 1500, and even more preferably 250 to 1000. Having the (weight average) molecular weight of the high refractive index component within this range facilitates the formation of a light diffusion control layer 12 having a desired regular internal structure. Note that, if the theoretical molecular weight of the high refractive index component can be determined based on its molecular structure, the (weight average) molecular weight of the high refractive index component refers to the theoretical molecular weight (not the weight average molecular weight). On the other hand, if the theoretical molecular weight is difficult to determine because the high refractive index component is, for example, a polymer component, the (weight average) molecular weight of the high refractive index component refers to the weight average molecular weight obtained as a value converted into standard polystyrene by gel permeation chromatography (GPC).

[0077] The refractive index of the high refractive index component is preferably 1.45 to 1.70, particularly preferably 1.50 to 1.65, and even more preferably 1.56 to 1.59. When the refractive index of the high refractive index component is within the above range, it becomes easier to form a light diffusion control layer 12 having a desired regular internal structure. Note that the refractive index in this specification means the refractive index of a predetermined component before the composition for the light diffusion control layer is cured, and this refractive index is measured in accordance with JIS K0062:1992.

[0078] The content of the high refractive index component in the composition for a light diffusion control layer is preferably 25 to 400 parts by mass, more preferably 40 to 300 parts by mass, particularly preferably 80 to 250 parts by mass, and even more preferably 120 to 200 parts by mass, per 100 parts by mass of the low refractive index component. This ensures that the regular internal structure of the formed light diffusion control layer 12 has regions derived from the high refractive index component and regions derived from the low refractive index component in the desired ratio. As a result, it becomes easier to form a light diffusion control layer 12 having the desired regular internal structure.

[0079] (2-2) Low Refractive Index Component Preferred examples of the low refractive index component include urethane (meth)acrylate, a (meth)acrylic polymer having a (meth)acryloyl group in the side chain, a (meth)acryloyl group-containing silicone resin, and an unsaturated polyester resin. In particular, it is preferable to use urethane (meth)acrylate.

[0080] 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.

[0081] Preferred examples of the (a) compound containing at least two isocyanate groups include aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, and 1,4-xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate (IPDI) and hydrogenated diphenylmethane diisocyanate, and biuret and isocyanurate forms thereof, as well as adducts (e.g., xylylene diisocyanate-based trifunctional adducts) that are reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, alicyclic polyisocyanates are preferred, and alicyclic diisocyanates containing only two isocyanate groups are particularly preferred.

[0082] Preferred examples of the above-mentioned (b) polyalkylene glycol include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyhexylene glycol, etc., and among these, polypropylene glycol is preferred.

[0083] The weight average molecular weight of the (b) polyalkylene glycol is preferably 2,300 to 19,500, more preferably 3,000 to 14,300, and even more preferably 4,000 to 12,300.

[0084] Preferred examples of the (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, and 4-hydroxybutyl(meth)acrylate.

[0085] The synthesis of a urethane (meth)acrylate using the above-mentioned components (a) to (c) as materials can be carried out according to a conventional method. In this case, from the viewpoint of efficiently synthesizing the urethane (meth)acrylate, the blending ratio of components (a) to (c) is preferably component (a):component (b):component (c)=1-5:1:1-5, and particularly preferably 1-3:1:1-3.

[0086] The weight average molecular weight of the low refractive index component is preferably 3000 to 20000, particularly preferably 5000 to 15000, and further preferably 7000 to 13000. When the weight average molecular weight of the low refractive index component is within the above range, it becomes easier to form a light diffusion control layer 12 having a desired regular internal structure.

[0087] The refractive index of the low refractive index component is preferably 1.30 to 1.59, more preferably 1.40 to 1.50, and particularly preferably 1.46 to 1.48, which makes it easier to form the light diffusion control layer 12 having a desired regular internal structure.

[0088] (2-3) Other Components The composition for the light diffusion control layer described above may contain other additives in addition to the high refractive index component and the low refractive index component. Examples of the other additives include polyfunctional monomers (compounds having three or more polymerizable functional groups), photopolymerization initiators, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, polymerization accelerators, polymerization inhibitors, infrared absorbers, plasticizers, diluents, and leveling agents.

[0089] Among the above-mentioned additives, the composition for light diffusion control layer preferably contains a photopolymerization initiator. When the composition for light diffusion control layer contains a photopolymerization initiator, it becomes easier to efficiently form the light diffusion control layer 12 having a desired regular internal structure.

[0090] 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-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2- propyl ketone, benzophenone, p-phenylbenzophenone, 4,4-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylamine benzoic acid ester, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane], etc. These may be used alone or in combination of two or more.

[0091] When a photopolymerization initiator is used, the content of the photopolymerization initiator in the composition for the light diffusion control layer is preferably 0.2 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the total amount of the high refractive index component and the low refractive index component, which makes it easier to efficiently form the light diffusion control layer 12.

[0092] (2-4) Preparation of composition for light diffusion control layer The composition for light diffusion control layer can be prepared by uniformly mixing the high refractive index component and low refractive index component described above, and, if desired, other additives such as a photopolymerization initiator.

[0093] During the mixing, a uniform composition for a light diffusion control layer may be obtained by stirring while heating to a temperature of 40 to 80° C. Furthermore, a dilution solvent may be added and mixed so that the resulting composition for a light diffusion control layer has a desired viscosity.

[0094] (2-5) Method for Forming Light Diffusion Control Layer The light diffusion control layer 12 can be formed by a conventionally known method. For example, the composition for the light diffusion control layer described above is prepared and applied to one side of a first release sheet to form a coating film, and then a second release sheet is attached to the side of the coating film opposite the first release sheet. The coating film is then irradiated with active energy rays through either release sheet to cure the coating film, thereby forming the light diffusion control layer 12. Alternatively, instead of attaching the second release sheet, the coating film may be irradiated with active energy rays in a nitrogen atmosphere to cure the coating film.

[0095] Examples of the coating method include knife coating, roll coating, bar coating, blade coating, die coating, and gravure coating. The composition for the light diffusion control layer may be diluted with a solvent as needed.

[0096] The active energy rays refer to electromagnetic waves or charged particle rays that have an energy quantum, and specific examples include ultraviolet rays, electron beams, etc. Among active energy rays, ultraviolet rays are particularly preferred because they are easy to handle.

[0097] When forming the louver structure, a linear light source is used as a light source of active energy rays, and the laminate surface is irradiated with band-like (almost linear) light that is random in the width direction (TD) and approximately parallel in the flow direction (MD). Note that the angle of irradiation of the light can also be adjusted to adjust the inclination angle of the plate-like regions formed in the louver structure.

[0098] When ultraviolet rays are used as the active energy rays, the irradiation conditions are such that the peak irradiance on the coating surface is 0.1 to 200 mW / cm ２ Furthermore, it is preferable that the integrated light amount on the coating surface is 5 to 300 mJ / cm ２ The relative moving speed of the light source of the active energy rays with respect to the laminate is preferably 0.1 to 10 m / min.

[0099] From the viewpoint of completing the curing more reliably, it is also preferable to irradiate the coating film with normal active energy rays (active energy rays that have not been converted into band-like light, scattered light) after curing using the band-like light as described above. In this case, when the coating film is irradiated with active energy rays in a nitrogen atmosphere instead of laminating the second process sheet, the surface of the coating film is exposed, but from the viewpoint of uniform curing, a release sheet may be laminated on the surface of the coating film.

[0100] (2-6) Thickness of Light Diffusion Control Layer The thickness of the light diffusion control layer 12 is preferably 20 μm or more, more preferably 50 μm or more, particularly preferably 80 μm or more, and even more preferably 85 μm or more. Having a thickness of 20 μm or more of the light diffusion control layer 12 facilitates the desired light diffusion properties. Furthermore, the thickness of the light diffusion control layer 12 is preferably 700 μm or less, more preferably 500 μm or less, particularly preferably 300 μm or less, even more preferably 200 μm or less, and even more preferably 150 μm or less, and most preferably 120 μm or less. Having a thickness of 700 μm or less of the light diffusion control layer 12 facilitates the prevention of dents and crushing.

[0101] 3. Display Device The display device 13 in this embodiment is not particularly limited as long as it can display content using an internal light source. Examples of the display device 13 include a liquid crystal display, an organic EL display, electronic paper, an electrophoretic display, a MEMS display, and a solid-state crystal display. Furthermore, the display device 13 may be a display having a touch panel laminated thereon.

[0102] 4. Other Configurations The display body 1 according to this embodiment may include components other than the light-scattering layer 11, the light diffusion control layer 12, and the display device 13. For example, the display body 1 may include at least one layer of transparent substrate. In particular, when the light-scattering layer 11 is the above-mentioned pressure-sensitive adhesive layer, it is preferable that a transparent substrate be laminated on at least one surface of the pressure-sensitive adhesive layer (particularly, the surface that will be the outermost layer).

[0103] Examples of the transparent substrate include a plastic film, a plastic plate, a glass plate, etc. When a process sheet or a release sheet is used in forming the light-scattering layer 11, these may be used as the transparent substrate.

[0104] Examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin films such as polyethylene and polypropylene; cellophane; diacetyl cellulose films; triacetyl cellulose films; acetyl cellulose butyrate films; polyvinyl chloride films; polyvinylidene chloride films; polyvinyl alcohol films; ethylene-vinyl acetate copolymer films; polystyrene films; polycarbonate films; polymethylpentene films; polysulfone films; polyether ether ketone films; polyether sulfone films; polyetherimide films; fluororesin films; polyamide films; acrylic resin films; polyurethane resin films; norbornene polymer films; cyclic olefin polymer films; cyclic conjugated diene polymer films; and vinyl alicyclic hydrocarbon polymer films, or laminate films thereof. Among these, polyethylene terephthalate films and polycarbonate films are preferred in terms of transparency, mechanical strength, and the like.

[0105] From the viewpoints of handleability, transparency, mechanical strength, etc., the thickness of the plastic film is preferably 10 to 200 μm, more preferably 15 to 150 μm, particularly preferably 20 to 100 μm, and even more preferably 25 to 80 μm.

[0106] The plastic plate is not particularly limited, and examples thereof include an acrylic plate, a polycarbonate plate, etc. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 10 mm, preferably 0.3 to 5 mm, and more preferably 0.5 to 3 mm.

[0107] The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, etc. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 10 mm, preferably 0.15 to 5 mm, and more preferably 0.2 to 3 mm.

[0108] The display body 1 according to the present embodiment also preferably includes a transparent adhesive layer for fixing together the components of the light scattering layer 11, the light diffusion control layer 12, and the display device 13. The adhesive constituting the transparent adhesive layer is not particularly limited as long as it has transparency, and for example, the adhesives exemplified as adhesives for constituting the light scattering layer 11 can be used.

[0109] The thickness of the transparent adhesive layer is preferably 1 to 200 μm, more preferably 3 to 100 μm, particularly preferably 5 to 60 μm, further preferably 8 to 30 μm, and most preferably 10 to 20 μm, which makes it easy to achieve both excellent visibility of the display content and strong fixation of members to each other.

[0110] 5. Physical Properties of Display Body The total light transmittance of a laminate (a laminate composed of a light scattering layer 11 and a light diffusion control layer 12) obtained by omitting the display device 13 from the display body 1 according to this embodiment is preferably 80 to 100%, more preferably 85 to 99%, and even more preferably 90 to 98%. This allows the display body 1 to have excellent visibility. Details of the method for measuring the total light transmittance are as described in the test examples below.

[0111] The haze value of the laminate (laminate composed of the light scattering layer 11 and the light diffusion control layer 12) obtained by omitting the display device 13 from the display body 1 according to this embodiment is preferably 40 to 100%, more preferably 55 to 98%, particularly preferably 70 to 96%, even more preferably 80 to 95%, and most preferably 85 to 94%. This makes it easier to achieve both high levels of brightness uniformity and excellent visibility. Details of the method for measuring the haze value are as described in the test examples below.

[0112] In the display 1 according to this embodiment, the luminance of light emitted in a direction perpendicular to the display surface (front direction) is 1 to 1200 cd / m as a value measured at a position 0.3 cm from the display surface. ２ It is preferable that the optical density is 4 to 500 cd / m ２ More preferably, it is 8 to 100 cd / m ２ It is preferable that the brightness is 10 to 40 cd / m ２ It is preferable that:

[0113] Furthermore, in the display 1 according to this embodiment, the luminance of light emitted in a direction at an angle of 45° to the display surface is 1 to 1200 cd / m as a value measured at a position 0.3 cm from the display surface. ２ It is preferable that the optical density is 3 to 500 cd / m ２ More preferably, it is 5 to 100 cd / m ２ It is preferable that the brightness is 6 to 30 cd / m ２ It is preferable that:

[0114] Furthermore, in the display 1 according to this embodiment, the luminance of light emitted in a direction at an angle of 60° to the display surface is 1 to 1200 cd / m as a value measured at a position 0.3 cm from the display surface. ２ It is preferable that the optical density is 3 to 500 cd / m ２ More preferably, it is 4 to 100 cd / m ２ It is preferable that the brightness is 5 to 30 cd / m ２ It is preferable that:

[0115] The display 1 according to this embodiment has luminance in the front direction, 45° direction, and 60° direction within the above-mentioned ranges, so that it is possible to display with well-uniform luminance. Details of the method for measuring the luminance are as described in the test examples below.

[0116] In the display 1 according to this embodiment, the maximum value of the slope of the luminance with respect to the angle (maximum slope) in the luminance distribution measured at a position 0.3 cm from the display surface in the range of -70° to 70°, with the direction perpendicular to the display surface being 0°, is preferably 0.01 to 2, more preferably 0.05 to 1, particularly preferably 0.1 to 0.6, and even more preferably 0.15 to 0.3. This makes it possible to display with more uniform luminance.

[0117] In the display 1 according to this embodiment, the ratio of the luminance of light emitted in a direction perpendicular to the display surface (front direction) to the luminance of light emitted in the front direction from the display device alone (0° luminance of the entire display device / 0° luminance of the display device alone) is preferably 60 to 100%, particularly preferably 70 to 96%, and even more preferably 80 to 92%. By exhibiting this ratio, the display 1 according to this embodiment exhibits sufficient luminance. Note that these luminance values ​​are values ​​measured at a position 0.3 cm from the display surface, and the details of the measurement are as described in the test examples below.

[0118] In the display 1 according to this embodiment, the ratio of the brightness of light emitted in a direction 45° from the display surface to the brightness of light emitted in a direction perpendicular to the display surface (front direction) (45° brightness / 0° brightness) is preferably 50 to 100%, more preferably 55 to 95%, particularly preferably 60 to 90%, and even more preferably 65 to 85%. This enables a display with better uniform brightness. Note that these brightness values ​​are measured at a position 0.3 cm from the display surface, and the details of the measurement are as described in the test examples below.

[0119] Furthermore, in the display 1 according to this embodiment, the ratio of the brightness of light emitted in a direction 60° relative to the display surface (60° brightness / 0° brightness) to the brightness of light emitted in a direction perpendicular to the display surface (front direction) is preferably 34 to 100%, more preferably 37 to 95%, particularly preferably 40 to 90%, and even more preferably 45 to 85%. This enables the display to be performed with a more uniform brightness. Note that these brightness values ​​are measured at a position 0.3 cm from the display surface, and the details of the measurement are as described in the test examples below.

[0120] 6. Manufacturing Method of Display Body The manufacturing method of the display body 1 according to the present embodiment is not particularly limited, and can be obtained, for example, by forming and preparing the light scattering layer 11, the light diffusion control layer 12, and the display device 13 (transparent substrate, transparent adhesive layer, etc., as necessary), and then laminating them to form a predetermined layer configuration.

[0121] When the light-scattering layer 11 is a pressure-sensitive adhesive layer, a coating solution of the pressure-sensitive adhesive composition described above is applied to one side of the process sheet or the release surface of the release sheet, and a heat treatment is performed to thermally crosslink the pressure-sensitive adhesive composition to form a coating layer. Then, by leaving a curing period as necessary, the coating layer can be made into a pressure-sensitive adhesive layer (light-scattering layer).

[0122] In this specification, when it is stated that "X to Y" (X and Y are any numbers), it means "X or more and Y or less" unless otherwise specified, and also means "preferably greater than X" or "preferably smaller than Y". Furthermore, when it is stated that "X or more" (X is any number), it means "preferably greater than X" unless otherwise specified, and when it is stated that "Y or less" (Y is any number), it also means "preferably smaller than Y" unless otherwise specified.

[0123] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0124] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0125] Example 1 1. Preparation of composition for light diffusion control layer To 40 parts by mass (solid content equivalent; the same applies hereinafter) of polyether urethane methacrylate as a low refractive index component, which had a weight average molecular weight of 9,900 and was obtained by reacting polypropylene glycol, isophorone diisocyanate, and 2-hydroxyethyl methacrylate, 60 parts by mass of o-phenylphenoxyethoxyethyl acrylate as a high refractive index component, which had a molecular weight of 268, and 8 parts by mass of 2-hydroxy-2-methyl-1-phenylpropan-1-one as a photopolymerization initiator, were added, and the mixture was heated and mixed at 80°C to obtain a composition for light diffusion control layer.

[0126] The weight average molecular weight (Mw) is a weight average molecular weight calculated as standard polystyrene, measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement conditions> Measurement device: HLC-8320, manufactured by Tosoh Corporation GPC columns (passed in the following order): TSK gel super H-H, TSK gel super HM-H, TSK gel super H2000, manufactured by Tosoh Corporation Measurement solvent: tetrahydrofuran Measurement temperature: 40°C

[0127] 2. Formation of Light Diffusion Control Layer The obtained light diffusion control layer composition was applied to the release surface of a release sheet R1 (thickness: 38 μm, sometimes referred to as the "first release sheet"), which was a polyethylene terephthalate film with one side treated with a silicone-based release agent, to form a coating film with a thickness of 60 μm. This resulted in a laminate consisting of the coating film and the first release sheet. Next, the release surface of a release sheet R2 (thickness: 38 μm, sometimes referred to as the "second release sheet"), which was a polyethylene terephthalate film with one side treated with a silicone-based release agent, was laminated on the coating film side of the laminate to obtain a laminate consisting of the first release sheet, the light diffusion control layer, and the second release sheet laminated in this order.

[0128] The resulting laminate was then placed on a conveyor, with the surface of the second release sheet facing upward and the longitudinal directions of the first and second release sheets parallel to the conveyor flow direction. An ultraviolet irradiation device (manufactured by Eye Graphics, product name "ECS-4011GX") equipped with a linear high-pressure mercury lamp and a cold mirror for focusing was then installed in front of the conveyor on which the laminate was placed. This device can irradiate the target with ultraviolet light focused in a band shape (almost linear). Note that the ultraviolet irradiation device was installed so that the longitudinal direction of the high-pressure mercury lamp was perpendicular to the conveyor flow direction.

[0129] Furthermore, when viewed from the longitudinal direction of the high-pressure mercury lamp, the irradiation angle of the ultraviolet light irradiated from the high-pressure mercury lamp to the laminate was set to 15° with respect to the normal to the laminate surface. Note that the irradiation angle here refers to the acute angle formed by the normal to the laminate surface and the ultraviolet light, expressed as a plus sign, when the ultraviolet light is irradiated toward the downstream side of the conveyor flow, with respect to the position directly below the high-pressure mercury lamp on the laminate, and the acute angle formed by the normal to the laminate surface and the ultraviolet light, expressed as a minus sign, when the ultraviolet light is irradiated toward the upstream side of the conveyor flow.

[0130] Thereafter, the conveyor was operated to move the laminate at a speed of 1.0 m / min, while applying a peak irradiance of 2.5 mW / cm2 to the coating surface. ２ , cumulative light intensity 40.0 mJ / cm ２ The coating film in the laminate was cured by irradiating it with ultraviolet light through the second release sheet under the conditions (this curing is sometimes referred to as "primary curing" for convenience).

[0131] Subsequently, while moving at a speed of 1.0 m / min, a peak irradiance of 190 mW / cm was applied to the coating film via the second release sheet. ２ , cumulative light intensity 180 mJ / cm ２The coating film in the laminate was cured by irradiating it with ultraviolet light (scattered light) under the conditions (this curing is sometimes referred to as "secondary curing" for convenience). The peak irradiance and integrated light quantity mentioned above were measured by placing a UV meter (manufactured by Eye Graphics, product name "Eye Ultraviolet Integrated Illuminance Meter UVPF-A1") equipped with a light receiver at the position of the coating film.

[0132] The above-mentioned coating film was sufficiently cured by the primary curing and secondary curing to form a light diffusion control layer. This resulted in a laminate comprising the first release sheet, the light diffusion control layer (thickness: 60 μm), and the second release sheet laminated in this order. Two such laminates were produced.

[0133] When a cross section of the light diffusion control layer formed as described above was observed using a microscope, it was confirmed that a louver structure was formed inside the light diffusion control layer, in which a plurality of plate-like regions 201 were arranged in parallel at predetermined intervals, as shown in Figure 4. It was also confirmed that the direction perpendicular to the longitudinal direction of the above-mentioned plate-like region 201 was inclined with respect to the thickness direction of the light diffusion control layer.

[0134] 3. Formation of Light-Scattering Layer 67.2 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of methyl methacrylate, 8 parts by mass of methacrylic acid, 18 parts by mass of vinyl acetate, 0.4 parts by mass of acrylic acid, and 1.4 parts by mass of 4-hydroxybutyl acrylate were polymerized by solution polymerization to obtain an acrylic copolymer. The weight-average molecular weight of this acrylic copolymer was measured using the method described above and found to be 820,000. The refractive index of this acrylic copolymer alone was also measured and found to be 1.48.

[0135] 100 parts by mass (solid content equivalent, the same applies hereinafter) of the obtained acrylic polymer, 0.47 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-165N") as a crosslinking agent, and 2.5 parts by mass of microparticles (manufactured by Momentive Performance Materials Japan, Inc., product name "Tospearl 145L", shape: spherical, average particle size: 4.5 μm, refractive index: 1.43) made of silicone resin (a silicon-containing compound having an intermediate structure between inorganic and organic) as light-diffusing microparticles were mixed in a solvent to obtain a coating liquid of a pressure-sensitive adhesive composition.

[0136] Next, the adhesive surface of a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name "Diafoil T600E", thickness: 38 μm, hereinafter sometimes referred to as "PET film") having adhesive surfaces on both sides was coated with the adhesive composition coating solution obtained as described above, and dried by heating, thereby obtaining a laminate in which an adhesive layer (light scattering layer) having a thickness of 23 μm was formed on the PET film.

[0137] 4. Formation of Transparent Pressure-Sensitive Adhesive Layer 100 parts by mass of the acrylic polymer prepared in the same manner as in step 3 above and 0.47 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-165N") as a crosslinking agent were mixed in a solvent to obtain a coating liquid of a pressure-sensitive adhesive composition (solid content concentration 28.4% by mass).

[0138] Next, the adhesive composition coating solution obtained as described above was applied to the release surface of release sheet R3 (thickness: 38 μm, sometimes referred to as "third release sheet"), which was a polyethylene terephthalate film with one side treated with a silicone-based release agent, and dried by heating, thereby obtaining a laminate in which a transparent adhesive layer with a thickness of 15 μm was formed on the third release sheet. Two such laminates were produced.

[0139] 5. Formation of Display Body The second release sheet was peeled off from the first laminate obtained in the above step 2, and the surface of the laminate obtained in the above step 3 on the light scattering layer side was attached to the exposed surface of the exposed light diffusion control layer. This resulted in a laminate (hereinafter sometimes referred to as "laminate A") having a layer structure of PET film / light scattering layer / light diffusion control layer / first release sheet.

[0140] Next, the first release sheet of laminate A was peeled off, and the surface of the transparent pressure-sensitive adhesive layer of the first laminate obtained in step 4 was attached to the exposed surface of the exposed light diffusion control layer. This resulted in a laminate (hereinafter sometimes referred to as "laminate B") having a layer structure of PET film / light scattering layer / light diffusion control layer / transparent pressure-sensitive adhesive layer / third release sheet.

[0141] Next, the second release sheet was peeled off from the second laminate obtained in step 2 above, exposing the light diffusion control layer. Meanwhile, the third release sheet was peeled off from laminate B above, exposing the transparent adhesive layer. The exposed surfaces of the light diffusion control layer and the transparent adhesive layer were then attached together. The two light diffusion control layers were laminated so that the conveyor flow direction during their manufacture was opposite to that of the two layers. This resulted in a laminate (hereinafter sometimes referred to as "Laminate C") having a layer structure of PET film / light scattering layer / light diffusion control layer / transparent adhesive layer / light diffusion control layer / first release sheet.

[0142] Furthermore, the first release sheet was peeled off from the laminate C, and the surface of the transparent pressure-sensitive adhesive layer of the second laminate obtained in step 4 was attached to the exposed surface of the exposed light diffusion control layer. This resulted in a laminate (hereinafter sometimes referred to as "laminate D") having a layer structure of PET film / light scattering layer / light diffusion control layer / transparent pressure-sensitive adhesive layer / light diffusion control layer / transparent pressure-sensitive adhesive layer / third release sheet.

[0143] Finally, the third release sheet was peeled off from the laminate D, and the exposed surface of the transparent pressure-sensitive adhesive layer was attached to the display surface of a smartphone (manufactured by SAMSUNG, product name "GALAXY S6") as an organic EL display device, thereby obtaining a display having a layer structure of PET film / light scattering layer / light diffusion control layer / transparent pressure-sensitive adhesive layer / light diffusion control layer / transparent pressure-sensitive adhesive layer / organic EL display device.

[0144] Examples 2 to 5 and 7 Displays were manufactured in the same manner as in Example 1, except that the thickness of the light diffusion control layer and the amount of light diffusing fine particles in the light diffusion control layer were changed as shown in Table 1.

[0145] Example 6 A display was manufactured in the same manner as in Example 1, except that polymer particles (PMMA-PSt) composed of methacrylic acid monomers and styrene monomers (manufactured by Sekisui Plastics Co., Ltd., product name "Techpolymer XX-02LA", average particle size: 5 μm, refractive index: 1.52) were used as the light-diffusing fine particles in an amount of 8 parts by mass per 100 parts by mass of the acrylic polymer.

[0146] Example 8 A display was manufactured in the same manner as in Example 1, except that when forming the light diffusion control layer, an ultraviolet spot parallel light source (manufactured by JATEC Co., Ltd.) in which the central light beam parallelism was controlled to within ±3° was used instead of an ultraviolet irradiation device (manufactured by iGraphics Co., Ltd., product name "ECS-4011GX") in which a linear high-pressure mercury lamp and a cold mirror for focusing were attached.

[0147] Furthermore, when the cross section of the light diffusion control layer formed in Example 8 was observed under a microscope, it was confirmed that a columnar structure consisting of a forest of pillars was formed inside the layer across the entire thickness direction. It was also confirmed that the pillars were tilted with respect to the thickness direction of the light diffusion control layer.

[0148] [Comparative Example 1] Except for omitting the PET film and the light scattering layer, a display body was manufactured in the same manner as in Example 1. The display body according to Comparative Example 1 had a layer structure of light diffusion control layer / transparent pressure-sensitive adhesive layer / light diffusion control layer / transparent pressure-sensitive adhesive layer / organic EL display device.

[0149] [Comparative Example 2] Except for omitting the transparent adhesive layer and the light diffusion control layer, a display body was manufactured in the same manner as in Example 1. The display body according to Comparative Example 1 had a layer structure of PET film / light scattering layer / organic EL display device.

[0150] [Test Example 1] (Measurement of Haze Value and Total Light Transmittance) The haze value (%) of the light-scattering layer (single layer) used in the examples and comparative examples was measured using a spectroscopic haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K 7136. The results are shown in Table 2.

[0151] Furthermore, for the laminates in which the organic EL display device was omitted from the displays produced in the examples and comparative examples, the total light transmittance (%) and haze value (%) were measured using a spectroscopic haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") The results are also shown in Table 2.

[0152] [Test Example 2] (Measurement of variable angle haze) For the light diffusion control layer (single layer) used in the examples and comparative examples, the incident light diffusion angle range where the haze value was 60% or more was measured using a variable angle haze meter (manufactured by Murakami Color Optical Laboratory, product name "HAZEMETER HM-150N").

[0153] Specifically, the light diffusion control layer was installed so that the distance from the integrating sphere opening of the variable angle haze meter to the arrival position of the measurement light was 62 mm. Next, the change in haze value (%) was measured by rotating the light diffusion control layer in its longitudinal direction (the transport direction during production) around the width direction of the light diffusion control layer at the arrival position as the rotation axis. That is, the incident angle of the measurement light relative to the light diffusion control layer was changed by changing only the inclination angle of the light diffusion control layer, and the haze value (%) was measured for each incident angle. Note that the incident angle at which the measurement light is normal to the display body is defined as 0°, and the rotation direction in which the travel direction of the longitudinal direction (the transport direction during production) of the light diffusion control layer approaches the light source is defined as positive, and measurements were performed in the range of -70° to 70°. The detailed measurement conditions were as follows: Light source: C light source; Measurement diameter: φ18 mm; Integrating sphere opening diameter: φ25.4 mm

[0154] The angle range in which the measured haze value (%) was 60% or more was identified as the incident light diffusion angle region. The start angle and end angle of the incident light diffusion angle region are shown in Table 2. For examples in which the incident light diffusion angle region is divided into two peaks, the start angle and end angle of the first peak and the second peak are shown in Table 2.

[0155] [Test Example 3] (Measurement of luminance distribution) For the displays manufactured in the examples and comparative examples, the organic EL display device was turned on to display a white screen at maximum luminance, and the luminance distribution was measured at a position 0.3 cm from the display surface in the range of -70° to 70°, with the direction perpendicular to the display surface being defined as 0°, using an imaging luminance meter (manufactured by Radiant Vision Systems, product name "Prometric I16 IC-PMI16 + Conoscope Lens 70° PM-CO-070-I"). Note that, as a reference example, the luminance distribution of a display consisting only of an organic EL display device was also measured.

[0156] From the obtained luminance distribution, luminance measured from the directions of -60°, -45°, 0° (front), 45° and 60° was read. The results are shown in Table 3.

[0157] In addition, the maximum value of the gradient of the brightness with respect to the angle was calculated from the obtained brightness distribution. Specifically, the above measurement yielded 2,985 coordinates (angle and brightness) from -70° to 70° as the brightness distribution, which was then divided into 75 sections starting from the coordinates on the -70° side of the angle. As a result, each of the 74 sections counting from the coordinates on the -70° side contained 40 coordinates, and only one section on the 70° side contained 25 coordinates. Here, only the section with 25 coordinates was excluded. Then, the average values ​​of brightness and angle (40-point average) were calculated for each section. Based on the 74 40-point averages obtained in this way, the maximum value of the absolute values ​​of the gradients of adjacent angles was taken as the maximum gradient. The results are shown in Table 3.

[0158] The ratio (%) of the 0° luminance of each example to the 0° luminance of the Reference Example was calculated. Specifically, the following formula was used: Ratio (%) = (0° luminance of each example) / (0° luminance of Reference Example) × 100. The results are shown in Table 3 as the ratio (%) of the 0° luminance to the Reference Example.

[0159] Furthermore, for each of the Examples, Comparative Examples, and Reference Examples, the ratios (%) of brightness at angles of -60°, -45°, 45°, and 60° to brightness at 0° were calculated. Specifically, the following formula was used: Ratio (%) = (Brightness at each angle) / (Brightness at 0°) × 100. The results are shown in Table 3.

[0160] Furthermore, the maximum slope value relative to the luminance at 0° was calculated for each of the examples, comparative examples, and reference examples. That is, the following formula was used: (maximum slope) / (luminance at 0°). The results are shown in Table 3.

[0161] [Test Example 4] (Visual Evaluation) For the displays manufactured in the Examples and Comparative Examples, and a display consisting only of an organic EL display device as a Reference Example, the organic EL display devices were turned on to display a white screen at maximum brightness. In this state, the displays were visually evaluated for (1) brightness when viewed from the front (0°) direction (front luminance), (2) uniformity of luminance when viewed from the front and from oblique directions, and (3) abrupt change in luminance when the viewing angle was changed from the front to an oblique direction, each based on the following criteria. The results are shown in Table 4.

[0162] (1) Front Brightness ⊚: Sufficiently bright when viewed from the front. ◯: Bright when viewed from the front. Δ: Slightly dark when viewed from the front, but at a level that is acceptable for practical use. ×: Dark when viewed from the front, at a level that is not acceptable for practical use.

[0163] (2) Uniformity of luminance ⊚: Uniformly bright in both the front and oblique directions. ◯: Brightness was slightly different in both the front and oblique directions. △: Brightness was different in both the front and oblique directions, but at a level that was acceptable for practical use. ×: Brightness was different in both the front and oblique directions to an extent that was not acceptable for practical use.

[0164] (3) Brightness Change ⊚: There was no change in brightness while changing the viewing angle from the front to an oblique direction. ◯: The brightness became slightly darker while changing the viewing angle from the front to an oblique direction. △: The brightness became darker while changing the viewing angle from the front to an oblique direction, but at a level that was acceptable for practical use. ×: The brightness became too suddenly dark while changing the viewing angle from the front to an oblique direction.

[0165]

[0166]

[0167]

[0168]

[0169] As can be seen from Table 4, the display obtained in the example had excellent uniformity of brightness and did not experience a sudden change in brightness even when the viewing angle was changed. Furthermore, the display obtained in the example also had sufficient brightness in the front direction. From the above, the display obtained in the example was able to view the screen with sufficient brightness regardless of the viewing angle.

[0170] The indicator of the present invention can be suitably used as an indicator that can be viewed from various viewing angles.

[0171] REFERENCE SIGNS LIST 1, 1'... display body 11... light scattering layer 12, 12a, 12b... light diffusion control layer 13... display device 201... plate-shaped region 202... region with relatively low refractive index

Claims

1. A display comprising: a light-scattering layer; at least one light diffusion control layer laminated on one side of the light-scattering layer and having a regular internal structure with a plurality of regions with a relatively high refractive index within a region with a relatively low refractive index; and a display device laminated on the side of the light diffusion control layer opposite the light-scattering layer, wherein at a position 0.3 cm from the display surface, in a luminance distribution measured in a range of -70° to 70°, with the direction perpendicular to the display surface being 0°, the ratio (maximum slope) of the maximum value of the slope with respect to the angle of luminance (maximum slope) to the luminance of light emitted in a direction perpendicular to the display surface (front direction) is 0.030 or less (maximum slope / 0° luminance).

2. The display according to claim 1, characterized in that the regular internal structure is a louver structure in which a plurality of plate-like regions with different refractive indices are alternately arranged in any one direction along the sheet surface.

3. The display according to claim 2, wherein the direction perpendicular to the longitudinal direction of said plate-like region is inclined with respect to the thickness direction of said light diffusion control layer.

4. The display according to claim 3, characterized in that the display comprises two or more layers of the light diffusion control layer, and the direction of inclination of the plate-like region differs among the multiple light diffusion control layers.

5. The display according to claim 1, wherein the light scattering layer contains light diffusing fine particles.

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