Light diffusion control member and reflective display body

Abstract

The present invention relates to a light diffusion control member (1a, 1b) provided with a light diffusion control layer (11) having a regular internal structure in which a plurality of regions (111) having a relatively high refractive index are provided in a region (112) having a relatively low refractive index, and a diffusion adhesive layer (12) containing light-diffusing fine particles, the light diffusion control layer (11) having a plurality of regions (111) having a relatively high refractive index being provided in a region (112) having a relatively low refractive index. L1, L2, and L3 determined by the reflected light measured by the light diffusion control members 1a, 1b satisfy L1 > 1.00... (1), 0.70 < = L2 < = 1.00... (2), and L3 < 2.00... (3). When the light diffusion control members (1a, 1b) are incorporated into a reflective display body capable of changing the vertical direction of display content, excellent visibility can be achieved regardless of the vertical direction of the display content.

Description

Technical Field

[0001] The present invention relates to a light diffusion control member and a reflective display including the light diffusion control member, wherein the light diffusion control member includes a light diffusion control layer capable of transmitting and diffusing incident light within a predetermined incident angle range in a state of strong light transmission and low light loss. Background Art

[0002] Among displays such as liquid crystal display devices, organic electroluminescent (EL) displays, and electronic paper, there are displays classified as reflective displays having a reflective layer. In such reflective displays, the display surface of the reflective display is usually illuminated by a light source such as indoor lighting or the sun, or a light source provided on the display surface side of the display, and the light from these light sources is reflected by the reflective layer, so that the display can be well visually recognized by the reflected light.

[0003] In a reflective display, due to the use of an external light source, the positional relationship between the light source and the visual identifier is usually not constant. Therefore, it is easy to cause problems such as insufficient light to reach the visual identifier due to the position of the light source, thereby reducing visual recognition and the display body as a whole cannot be brightly illuminated. In order to solve such problems, it is considered to assemble a light diffusion plate to the display body. However, by simply assembling a conventional light diffusion plate, there will be problems such as the inability to fully obtain the light diffusivity required for obtaining good visual recognition, or the light loss caused by stray light or backscattering in order to achieve high light diffusion, which impairs the image clarity. From the perspective of solving these problems, it is studied that in a reflective display, a light diffusion control layer is provided between the surface on the visual identifier side and the reflective layer, which can transmit and diffuse the incident light within a specified incident angle range in a strong and low light loss state.

[0004] For example, Patent Documents 1 and 2 disclose a light diffusion control member having the light diffusion control layer and an isotropic light diffusion layer containing light diffusing particles. In such a light diffusion control member, due to the presence of the light diffusion control layer, light reflected by the reflective layer is appropriately diffused, thereby reducing the decrease in visual recognition depending on the position of the light source.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 6981984

[0008] Patent Document 2: Japanese Patent No. 6993976 Summary of the invention

[0009] 1. Technical issues to be resolved

[0010] However, in recent years, most smartphones or tablets have a function of switching the vertical direction of the displayed content according to the vertical position of the display surface. That is, when the short side of the display surface is parallel to the ground, the vertical direction of the displayed content is displayed in a manner parallel to the long side of the display surface, and when the long side of the display surface is parallel to the ground, the vertical direction of the displayed content is displayed in a manner parallel to the short side of the display surface.

[0011] In such a reflective display body configured in such a manner that the vertical direction of the display content on the display surface can be changed, when the vertical direction of the display content is changed, there is a problem that the effect of improving visual recognizability by the above-mentioned light diffusion control layer cannot be fully obtained. For example, even if the short side of the display surface is parallel to the ground and the vertical direction of the display content is displayed in a manner parallel to the long side of the display surface, good visual recognizability can be obtained, but when the long side of the display surface is parallel to the ground and the vertical direction of the display content is displayed in a manner parallel to the short side of the display surface, the light diffusion control layer cannot fully exert its effect, and the problem of insufficient visual recognizability still exists.

[0012] The present invention has been completed in view of such actual conditions, and its purpose is to provide a light diffusion control component that can achieve excellent visual recognizability regardless of the up and down direction of the displayed content even when assembled into a reflective display body that can change the up and down direction of the displayed content, and a reflective display body with such visual recognizability.

[0013] (II) Technical solution

[0014] In order to achieve the above-mentioned object, first, the present invention provides a light diffusion control member (Invention 1), characterized in that it comprises: a light diffusion control layer and a diffusion adhesive layer, the light diffusion control layer having a regular internal structure having a plurality of regions with a relatively high refractive index in a region with a relatively low refractive index, the diffusion adhesive layer being laminated on one surface side of the light diffusion control layer and containing light diffusing particles, wherein, for any point on the surface of one side of the light diffusion control member of a measurement sample in which any one surface of the light diffusion control member is laminated on the reflecting surface of any reflecting mirror, light rays with an angle of 30° with respect to the normal line of the surface are irradiated from four directions with azimuth angles of 0°, 90°, 180° and 270° centered on the point, respectively, so that reflected light diffusely reflected from the point is generated at each of the azimuth angles, and for For the reflected light in the reflected light that enters a plane that includes the point and the normal and is perpendicular to the azimuth angle at which the light is irradiated and that forms an angle of less than 30° with the normal, the standard deviation (cd / m2) of the brightness of these reflected lights is calculated for each azimuth angle, and the azimuth angle that gives the maximum standard deviation is taken as the exclusion angle. For any point on the surface of the light diffusion control component side of the measurement sample, light rays that form an angle of 30° with the normal to the surface are irradiated in three directions from the azimuth angles in the four directions excluding the exclusion angle, so that each of the three azimuth angles generates reflected light diffusely reflected from the point, and the brightness (cd / m 2 ), the minimum brightness value among the three brightnesses obtained is set as L min , set the maximum brightness value to L max For any point on a surface of any standard white plate, the L min The azimuth angle of the light irradiated by the normal line of the one surface is 30°, and the brightness (cd / m 2 ) is set to L STD hour,

[0015] L1=L min / L STD The L1 represented by satisfies the following formula (1),

[0016] L1>1.00…(1),

[0017] L2=L min / L max The L2 represented by satisfies the following formula (2),

[0018] 0.70≤L2≤1.00…(2),

[0019] When the standard deviations (cd / m2) of the azimuth angles in three directions excluding the exclusion angle among the azimuth angles in the four directions are respectively set as L3, all L3 in the three directions satisfy the following formula (3):

[0020] L3<2.00…(3).

[0021] By making the light diffusion control component of the above-mentioned invention (Invention 1) satisfy the above-mentioned conditions of L1, L2 and L3 while having a light diffusion control layer and a diffusion adhesive layer, when assembled into a reflective display body that can change the vertical direction of the display content, even if the vertical direction of the display content is changed, uniform and good brightness can be achieved, resulting in excellent visual recognition.

[0022] In the above invention (Invention 1), preferably: the region with a relatively high refractive index is a columnar structure extending from one surface side of the light diffusion control layer to the other surface side, the light diffusion control layer has at least one layer composed of a columnar structure in which the columns are standing in the region with a relatively low refractive index, and in at least a portion of the columnar structure, a straight line parallel to the extending direction is inclined relative to the thickness direction of the light diffusion control member (Invention 2).

[0023] In the above invention (Invention 2), preferably, in at least one layer of the layer composed of the columnar structure, the columnar object is bent between one end and the other end thereof (Invention 3).

[0024] In the above invention (Invention 2), preferably, the light diffusion control layer includes two layers consisting of the columnar structure (Invention 4).

[0025] In the above invention (Invention 1), preferably, the light diffusion control layer includes an intermediate adhesive layer laminated between the light diffusion control layer and the diffusion adhesive layer, and the intermediate adhesive layer is composed of an adhesive containing a carboxyl group (Invention 5).

[0026] In the above invention (Invention 1), it is preferred that the light diffusing fine particles are fine particles composed of a silicon-containing compound having an intermediate structure between inorganic and organic (Invention 6).

[0027] Second, the present invention provides a reflective display body, which is a reflective display body constructed in a manner capable of changing the up and down directions of display contents on a display surface, and comprises: the light diffusion control member (Invention 1); a display device arranged on any one side of the light diffusion control member; and a reflective layer (Invention 7) arranged on a side of the display device opposite to the light diffusion control member or assembled in the display device.

[0028] (III) Beneficial effects

[0029] According to the light diffusion controlling member of the present invention, a reflective display body capable of achieving excellent visibility regardless of the up-down direction of displayed content can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a cross-sectional view of a light diffusion controlling member according to one embodiment of the present invention.

[0031] Figure 2 It is a cross-sectional view of a light diffusion controlling member according to another embodiment of the present invention.

[0032] Figure 3 This is a cross-sectional view of an example of a reflective display produced using the light diffusion controlling member according to one embodiment of the present invention.

[0033] Figure 4 : is a perspective view schematically showing an example (column structure) of a regular internal structure of the light diffusion controlling layer in one embodiment of the present invention.

[0034] Figure 5 It is a perspective view illustrating various directions regarding the light diffusion control layer in one embodiment of the present invention.

[0035] Figure 6 It is a diagram for explaining a method of measuring optical properties in a light diffusion controlling member according to one embodiment of the present invention.

[0036] Figure 7 It is a diagram for explaining a method of measuring optical properties in a light diffusion controlling member according to one embodiment of the present invention. DETAILED DESCRIPTION

[0037] Hereinafter, embodiments of the present invention will be described.

[0038] Figure 1 1 is a cross-sectional view showing a light diffusion control member according to an embodiment of the present invention. Figure 1 As shown, the light diffusion control component 1a comprises: a light diffusion control layer 11 and a diffusion adhesive layer 12, wherein the light diffusion control layer 11 has a regular internal structure having multiple relatively high refractive index regions in a relatively low refractive index region, and the diffusion adhesive layer 12 is stacked on one surface side of the light diffusion control layer 11 and contains light diffusing particles.

[0039] Figure 2 FIG. 2 is a cross-sectional view showing a light diffusion control member according to another embodiment of the present invention. Figure 2As shown, the light diffusion control member 1 b includes the light diffusion control layer 11 and the diffusion adhesive layer 12 similarly to the light diffusion control member 1 a , and further includes an intermediate adhesive layer 13 laminated between the light diffusion control layer 11 and the diffusion adhesive layer 12 .

[0040] In addition, the form of the light diffusion controlling members 1 a and 1 b according to the present embodiment is not particularly limited, but is preferably in a film shape, a plate shape, or the like, and is particularly preferably in a film shape.

[0041] The light diffusion controlling members 1a and 1b of the present embodiment can be suitably used in the production of a reflective display. Figure 3 , a cross-sectional view of an example of such a reflective display is shown in FIG. The reflective display 100 comprises: the above-mentioned light diffusion control members 1a and 1b; a display device 2 provided on one side of the light diffusion control members 1a and 1b; and a reflective layer 3 provided on a side of the display device 2 opposite to the light diffusion control members 1a and 1b. Among them, which side of the light diffusion control members 1a and 1b (the side on the light diffusion control layer 11 side or the side on the diffusion adhesive layer 12 side) is laminated on the display device 2 and the reflective layer 3 can be appropriately selected according to the structure of the reflective display 100 to be manufactured. In addition, the reflective display 100 of the present embodiment is preferably a display configured in a manner that can change the up-down direction of the display content on the display surface.

[0042] In the light diffusion control members 1a and 1b of the present embodiment, the light diffusion control layer 11 has a regular internal structure having a plurality of relatively high refractive index regions in a relatively low refractive index region as described above. As an example of such a regular internal structure, Figure 4 The column structure is schematically shown in FIG. (Details are described later). Figure 4As shown in (a) to (c) of FIG. 1 , the light diffusion control layer 11 has the following structure: a plurality of regions 111 (columns) with relatively high refractive indexes extend in the thickness direction, and regions 112 with relatively low refractive indexes fill the surroundings. The regular internal structure refers to an internal structure in which a plurality of regions 111 with relatively high refractive indexes are arranged with a predetermined regularity in the regions 112 with relatively low refractive indexes. Such an internal structure refers to, for example, an internal structure in which, when observing a cross section obtained by cutting the light diffusion control layer 11 with a plane parallel to the surface of the light diffusion control layer 11, that is, a cross section obtained by cutting at a position where the regular internal structure exists, in the regions 112 with relatively low refractive indexes, regions 111 with relatively high refractive indexes are repeatedly arranged at approximately the same pitch along at least one direction in the cross section. Furthermore, the regular internal structure here is a structure in which the relatively high refractive index region 111 extends in the thickness direction of the light diffusion control layer 11, which is different from a phase separation structure in which one phase exists in another phase without clear regularity, or a sea island structure in which approximately spherical island components exist in a sea component. Figure 4 The details of the differences in the structures shown in (a) to (c) will be described later.

[0043] The light diffusion controlling members 1a and 1b of the present embodiment satisfy predetermined optical characteristics when light is irradiated onto the surface on the light diffusion controlling layer 11 side to generate diffusely reflected reflected light. The optical characteristics will be described below.

[0044] First, the measurement method for determining the above-mentioned optical characteristics will be described. Figure 6 The steps of preparing a measurement sample and irradiating the obtained measurement sample with a predetermined light are shown in FIG. Figure 6 As shown in (a), one of the surfaces of the light diffusion control members 1a and 1b is laminated on the reflection surface of the reflection mirror 4 to prepare a measurement sample 200. Figure 6 As shown in (b) (the plane of the measurement sample 200 observed from the surface on the light diffusion control member 1 side), any point on the surface on the light diffusion control member 1a, 1b side of the measurement sample 200 is assumed to be an irradiation point 201, and four directions with azimuth angles of 0°, 90°, 180° and 270° are assumed with the irradiation point 201 as the center. Figure 6 As shown in (c), the irradiation point 201 is irradiated with a light 202 having an angle of 30° with the normal line of the surface on the light diffusion control member 1 side from any of the above four azimuth angles.

[0045] When the light diffusion control members 1a and 1b are laminated on the reflector 4, although any surface of the light diffusion control members 1a and 1b may be laminated on the reflector 4, it is preferred that the surface be oriented in the direction of the reflective layer 3 when constituting the reflective display 100. That is, when the surface of the light diffusion control layer 11 side of the light diffusion control members 1a and 1b is laminated on the reflective layer 3, it is preferred that the surface be laminated on the reflective mirror 4 to form the measurement sample 200. Furthermore, when the surface of the light diffusion control members 1a and 1b on the diffusion adhesive layer 12 side is laminated on the reflective layer 3, it is preferred that the surface be laminated on the reflective mirror 4 to form the measurement sample 200.

[0046] In addition, the "reflector" in this specification refers to a mirror formed by laminating a metal film on one side of a glass plate, and the "reflecting surface" of the reflector refers to the surface of the metal film on the opposite side of the glass plate. As the metal constituting the metal film, aluminum, silver, etc. can be preferably listed.

[0047] The irradiated light 202 is diffusely reflected by the measurement sample 200, thereby generating reflected light. When obtaining the optical characteristics of the light diffusion control members 1a and 1b, the brightness of a part of the generated reflected light is measured. There are two types of such reflected light to be measured. Figure 7 Explain it.

[0048] Figure 7 (a) shows the first measurement target. As shown in the figure, the reflected light 203 from the irradiation point 201 toward the normal direction (front direction) of the surface of the light diffusion control member 1a, 1b side is the first measurement target.

[0049] Figure 7 First, as shown in the figure, a plane P is assumed, which is a plane including the irradiation point 201 and the normal line of the surface of the light diffusion control member 1a, 1b side, and its azimuth angle relative to the irradiated light 202 (in Figure 7 (b) is 0°) vertical (in other words, at Figure 7 (b) is parallel to the azimuth angles of 90° and 270°). Furthermore, among the reflected light of the light ray 202 that is diffusely reflected, the reflected light ( Figure 7 In (b), a set of reflected light that forms a fan shape with reflected light 204a and reflected light 204b as ends) is the second measurement object.

[0050] Next, the “exclusion angle”, “L min " "L max ” and “L STD" and other concepts are explained.

[0051] The "exclusion angle" refers to an angle determined as follows. First, the measurement sample prepared in the above manner is irradiated with light as described above, and the reflected light ( Figure 7 In (b), the reflected light 204a and the reflected light 204b are the ends of the fan-shaped reflected light. In addition, for the reflected light, the standard deviation of the brightness (cd / m 2 ) value. The azimuth angle of the standard deviation that gives the maximum value among the four standard deviations thus obtained is the "exclusion angle".

[0052] Then, "L min ” and “L max " are determined in the following manner. First, the measurement sample prepared as described above is irradiated with light as described above to generate the reflected light of the first measurement object (such as Figure 6 As shown in (c), the reflected light 203 in the normal direction (front direction) of the surface of the light diffusion control member 1a, 1b side is measured, and its brightness (cd / m 2 ). Among them, the azimuth angle when irradiating light is only the three directions after removing the above-mentioned "exclusion angle" from the four directions with azimuth angles of 0°, 90°, 180° and 270°. And, the value of the minimum brightness among the three brightness obtained is set as "L min ”, set the maximum brightness value to “L max ”.

[0053] Finally, "L STD " refers to the brightness measured using an arbitrary standard white plate as a reference. Specifically, for any point on one surface of an arbitrary standard white plate, the above L min The azimuth angle of the light irradiated by the normal line of the one surface is 30 degrees, and the reflected light is diffusely reflected from the above point in the front direction. And the brightness of the reflected light (cd / m 2 ) is determined as "L STD ". In addition, the "standard white plate" in this specification refers to a reflective plate with a reflectivity of 99% or more. The "standard white plate" is a calibration reference for optical measurements. By using the "standard white plate", deviations in the intensity of the measured light caused by differences in light sources can be eliminated.

[0054] In the above case, it is preferable that the light diffusion control members 1a and 1b of the present embodiment have L1=L min / L STD The L1 represented by satisfies the following formula (1),

[0055] L1>1.00…(1)

[0056] By making the light diffusion controlling members 1a and 1b of the present embodiment satisfy the formula (1), even in the case of the lowest brightness (L min ), a higher brightness than the diffusion (Lambertian diffusion (LSTD) produced by a standard white plate can be obtained. Therefore, in a reflective display body assembled with light diffusion control components 1a, 1b, a brighter display can be easily achieved by irradiating the display surface with light from various azimuth angles. From this perspective, L1 is preferably greater than 1.10, more preferably greater than 1.20, particularly preferably greater than 1.30, further preferably greater than 1.40, and most preferably greater than 1.45. In addition, the upper limit value of L1 is not particularly limited, for example, it is preferably less than 4.00, more preferably less than 3.00, particularly preferably less than 2.00, further preferably less than 1.60, and preferably less than 1.50.

[0057] In addition, the light diffusion control members 1a and 1b of this embodiment are preferably L2=L min / L max The L2 represented by satisfies the following formula (2),

[0058] 0.70≤L2≤1.00…(2)

[0059] By making the light diffusion controlling members 1a and 1b of the present embodiment satisfy the formula (2), when the brightness is the lowest (L min ) and the highest brightness (L max ) becomes smaller. Therefore, in a reflective display body assembled with a light diffusion control member 1, even when the reflective display body is placed horizontally to change the positional relationship between the display surface and the external light source, the change in the brightness of the display can be suppressed, and uniform brightness can be easily achieved. From this perspective, L2 is particularly preferably above 0.71, and more preferably above 0.72. In addition, the upper limit value of L2 is not particularly limited as long as it is below 1.00. From the perspective of easily combining L3 described later, it is preferably below 0.95, more preferably below 0.90, particularly preferably below 0.85, more preferably below 0.80, more preferably below 0.76, and most preferably below 0.73.

[0060] Furthermore, in the light diffusion control members 1a and 1b of the present embodiment, when the values ​​of the standard deviations of the brightness in the three directions excluding the exclusion angle in the standard deviation of the brightness are respectively set as L3, it is preferred that all L3 in these three directions satisfy the following formula (3):

[0061] L3<2.00…(3)

[0062] By making the light diffusion control components 1a and 1b of the present embodiment satisfy the formula (3), even when light is irradiated from any direction, in the reflective display body assembled with the light diffusion control components 1a and 1b, uniform light can be well diffused toward the horizontal direction of the visual recognizer. Therefore, the right eye and the left eye of the visual recognizer can visually recognize the display with the same degree of brightness, and it is not easy to recognize uneven brightness. From this perspective, L3 is preferably less than 1.6, more preferably less than 1.2, particularly preferably less than 1.1, and further preferably less than 1.05. In addition, the lower limit value of L3 is not particularly limited, for example, it is preferably greater than 0.01, more preferably greater than 0.1, and particularly preferably greater than 0.15.

[0063] In previous reflective displays, for example, when the reflective display is placed horizontally to change the vertical direction of the display content, there will be problems such as light irradiated from above the display not being able to be fully diffused in the front direction, or the brightness of the display will change significantly as the irradiation direction changes.

[0064] In this regard, in the light diffusion control components 1a and 1b of the present embodiment, by satisfying the above-mentioned conditions of L1, L2 and L3, the reflective display body assembled with the light diffusion control components 1a and 1b has excellent visual recognition. Specifically, compared with the case where the light diffusion control components 1a and 1b are not provided, the light irradiated from the outside can be effectively diffusely reflected in the front direction, thereby achieving a bright display. In addition, for example, when the up and down direction of the display content is changed by placing the reflective display body horizontally, the change in the brightness of the display accompanying the change in the up and down direction can also be suppressed, and a uniform brightness display can be achieved. Furthermore, even when the direction of the light irradiated from the outside is changed, it is possible to diffusely reflect the horizontal direction of the visual recognizer with uniform brightness, so that the visual recognizer is not easy to recognize the uneven brightness.

[0065] The details of the above-mentioned brightness measurement method are as described in the test examples described later.

[0066] 1. Light diffusion control layer

[0067] The light diffusion control layer 11 of the present embodiment is not particularly limited as long as it has a regular internal structure including a plurality of relatively high refractive index regions 111 in a relatively low refractive index region 112 and satisfies the above-mentioned conditions of L1, L2, and L3.

[0068] From the perspective of being easy to form a regular internal structure as described above and being easy to satisfy the above-mentioned conditions of L1, L2 and L3, the light diffusion control layer 11 of this embodiment is preferably formed by curing a composition for a light diffusion control layer, wherein the composition for a light diffusion control layer contains 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, the high refractive index component and the low refractive index component are preferably components having one or two polymerizable functional groups, respectively.

[0069] (1) High refractive index component

[0070] As the preferred example of 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, anthraceneoxyalkyl (meth) acrylate, benzylphenoxyalkyl (meth) acrylate, etc. can be listed, and a part of these is replaced by halogen, alkyl, alkoxy, haloalkyl, etc. to form materials, etc. Wherein, from the perspective of easily forming a good regular internal structure, satisfying the conditions of the above-mentioned L1, L2 and L3, preferably biphenyl (meth) acrylate, specifically, preferred acrylate o-phenylphenoxyethyl, acrylate o-phenylphenoxyethoxyethyl, etc. In addition, in this manual, (meth) acrylic acid refers to both acrylic acid and methacrylic acid. Other similar terms are also the same.

[0071] The molecular weight of the high refractive index component is preferably 150 to 2500, particularly preferably 200 to 1500, and further preferably 250 to 1000. By having the molecular weight within the above range, it is easy to form a light diffusion control layer 11 having a desired regular internal structure, and it is easy to satisfy the above-mentioned conditions of L1, L2 and L3. In addition, when the theoretical molecular weight of the high refractive index component can be determined based on the molecular structure, the molecular weight of the high refractive index component refers to the theoretical molecular weight. On the other hand, when the high refractive index component is difficult to determine the theoretical molecular weight due to, for example, a polymer component, the molecular weight of the high refractive index component refers to the weight average molecular weight obtained as a value converted to standard polystyrene measured by gel permeation chromatography (GPC). In addition, the method for determining the weight average molecular weight in this specification refers to a value converted to standard polystyrene measured by the GPC method.

[0072] The refractive index of the high refractive index component is preferably 1.45 to 1.70, more preferably 1.50 to 1.65, particularly preferably 1.54 to 1.62, and further preferably 1.56 to 1.59. By having the refractive index within the above range, it is easy to form a light diffusion control layer 11 having a desired regular internal structure, and it is easy to satisfy the above-mentioned conditions of L1, L2 and L3. 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 a value measured according to JIS K0062:1992.

[0073] The content of the high refractive index component in the light diffusion control layer composition is preferably 25 to 400 parts by mass, more preferably 50 to 350 parts by mass, particularly preferably 75 to 300 parts by mass, and further preferably 100 to 200 parts by mass relative to 100 parts by mass of the low refractive index component. When the content is within the above range, in the regular internal structure of the formed light diffusion control layer 11, the region from the high refractive index component and the region from the low refractive index component exist in a desired ratio, and it is easy to form a desired regular internal structure, and it is easy to satisfy the above-mentioned conditions of L1, L2 and L3.

[0074] (2) Low refractive index component

[0075] Preferred examples of low refractive index components include carbamate (meth) acrylates, (meth) acrylic polymers with (meth) acryloyl groups in the side locks, silicone resins containing (meth) acryloyl groups, unsaturated polyester resins, etc. Among them, carbamate (meth) acrylates are particularly preferred from the perspective of easily forming a good regular internal structure while satisfying the above-mentioned L1, L2 and L3 conditions. More specifically, carbamate (meth) acrylates formed by (a) a compound containing at least 2 isocyanate groups, (b) a polyalkylene glycol, and (c) a hydroxyalkyl (meth) acrylate are preferably used.

[0076] 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, and 1,4-xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and their biuret bodies, isocyanurate bodies, and adducts of reaction products with low molecular weight 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 are particularly preferred.

[0077] Preferred examples of the polyalkylene glycol (b) include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol, etc., among which polypropylene glycol is preferred. The weight average molecular weight of the polyalkylene glycol (b) is preferably 2,300 to 19,500, particularly preferably 3,000 to 14,300, and further preferably 4,000 to 12,300.

[0078] 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 (meth)acrylate is preferred.

[0079] The synthesis of urethane (meth) acrylate using the above components (a) to (c) as materials can be carried out according to a common method. In this case, from the perspective of efficiently synthesizing urethane (meth) acrylate, the blending ratio of components (a) to (c) is preferably (a) component: (b) component: (c) component = 1-5:1:1-5, and particularly preferably 1-3:1:1-3 in terms of molar ratio.

[0080] 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 is within the above range, it is easy to form a light diffusion control layer 11 having a desired regular internal structure, and it is easy to satisfy the above conditions of L1, L2 and L3.

[0081] The refractive index of the low refractive index component is preferably 1.30 to 1.59, more preferably 1.38 to 1.50, particularly preferably 1.42 to 1.49, and further preferably 1.46 to 1.48 or less. By keeping the refractive index within the above range, it is easy to form a light diffusion control layer 11 having a desired regular internal structure, and it is easy to satisfy the above conditions of L1, L2, and L3.

[0082] (3) Other additives

[0083] In addition to the high refractive index component and the low refractive index component, the above-mentioned light diffusion control layer composition may also contain other additives. As other additives, for example, multifunctional monomers (compounds having three or more polymerizable functional groups), photopolymerization initiators, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, polymerization accelerators, inhibitors, infrared absorbers, plasticizers, diluent solvents, and leveling agents can be listed.

[0084] (3-1) Photopolymerization Initiator

[0085] The composition for the light diffusion control layer preferably contains a photopolymerization initiator as another additive, thereby making it easy to efficiently form the light diffusion control layer 11 having a desired regular internal structure and to easily satisfy the above-mentioned conditions of L1, L2, and L3.

[0086] 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-( 4-(1-methylvinyl)phenyl]propane], etc. These may be used alone or in combination of two or more.

[0087] When a photopolymerization initiator is used, the content of the photopolymerization initiator in the light diffusion control layer composition is preferably 0.2 to 20 parts by mass, more preferably 0.5 to 16 parts by mass, particularly preferably 1 to 13 parts by mass, and further 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. By making the content within the above range, it is easy to effectively form a light diffusion control layer 11 having a desired regular internal structure, and it is easy to satisfy the above-mentioned conditions of L1, L2 and L3.

[0088] (3-2) Ultraviolet light absorber

[0089] The composition for the light diffusion control layer preferably contains an ultraviolet absorber as another additive. When the ultraviolet absorber is contained, when the coating film of the light diffusion control layer composition is irradiated with active energy rays, the ultraviolet absorber selectively absorbs active energy rays of a specified wavelength within a specified range. By optimizing the type or amount of the ultraviolet absorber, bending can be easily generated in the formed area 111 (columnar) with a relatively high refractive index without hindering the curing of the light diffusion control layer composition. As a result, the light diffusion control layer 11 can achieve a wider angle range of light diffusion and more easily meet the above-mentioned conditions of L1, L2 and L3.

[0090] As the ultraviolet absorber, there can be listed benzotriazole ultraviolet absorbers, hydroxyphenyltriazine ultraviolet absorbers, benzophenone ultraviolet absorbers, hydroxybenzoate ultraviolet absorbers, etc. Among them, benzotriazole ultraviolet absorbers are preferably used. The above ultraviolet absorbers can be used alone or in combination of two or more.

[0091] When using an ultraviolet absorber, the content of the ultraviolet absorber in the light diffusion control layer composition is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 1 parts by mass, particularly preferably 0.03 to 0.5 parts by mass, and further preferably 0.06 to 0.1 parts by mass, relative to the total amount of 100 parts by mass of the high refractive index component and the low refractive index component. By setting the content of the ultraviolet absorber to the above range, it is possible to effectively generate bending in the region 111 (columnar) with a relatively high refractive index. As a result, the light diffusion control layer 11 can achieve a wider angle range of light diffusion and more easily meet the above-mentioned conditions of L1, L2 and L3.

[0092] (4) Preparation of Composition for Light Diffusion Control Layer

[0093] The composition for a light diffusion control layer can be prepared by uniformly mixing the high refractive index component and the low refractive index component, and other additives such as a photopolymerization initiator and an ultraviolet absorber added as desired.

[0094] 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 mixed dilution solvent may be added to adjust the viscosity of the obtained composition for a light diffusion control layer to a desired value.

[0095] (5) Internal structure of rules

[0096] As described above, the light diffusion control layer 11 of the present embodiment has a regular internal structure therein, wherein the regular internal structure has a plurality of relatively high refractive index regions 111 in a relatively low refractive index region 112. Examples of the regular internal structure include, in addition to the above-mentioned columnar structure, a louver structure in which a plurality of plate-like regions with different refractive indices are alternately arranged in any direction along the film surface.

[0097] In the light diffusion control layer 11 of the present embodiment, the regular internal structure is preferably a columnar structure from the perspective of easily satisfying the above-mentioned conditions of L1, L2 and L3. More specifically, in the light diffusion control layer 11 of the present embodiment, the region with a relatively high refractive index is a columnar object 111 extending from one surface side of the light diffusion control layer 11 to the other surface side, and the light diffusion control layer 11 preferably has at least one layer formed by a columnar structure formed by a forest of columnar objects 111 in a region with a relatively low refractive index. Figure 4 FIG. 1 is a perspective view schematically showing such a column structure.

[0098] When light incident on the light diffusion control layer 11 having such a columnar structure is within a specified range of incident angles, it is emitted from the light diffusion control layer 11 while being strongly diffused at a specified opening angle. On the other hand, when the incident light is incident at an angle outside the above-mentioned range of incident angles, it is transmitted without being diffused, or is emitted in a manner accompanied by a diffusion weaker than that of the incident light within the range of incident angles. In addition, when a contrast agent is provided parallel to the surface of the light diffusion control layer 11, the diffused light caused by the incident light within the above-mentioned range of incident angles generated by the columnar structure becomes a circle or a nearly circular shape (ellipse, etc.) that diffuses in any direction. On the other hand, when the above-mentioned diffusion caused by the incident light outside the above-mentioned range of incident angles is weak, a crescent-shaped diffused light is formed.

[0099] Furthermore, in the light diffusion control layer 11 of the present embodiment, from the perspective of easily satisfying the above-mentioned conditions of L1, L2 and L3, in at least a portion of the columnar objects 111, the straight line parallel to the above-mentioned extending direction is preferably inclined with respect to the thickness direction of the light diffusion control members 1a and 1b. Figure 4 The three column structures shown are all inclined structures. Figure 4 The column structure shown in (b) is in the form of two layers of stacked columns 111, one layer (the upper layer in the figure) is columns 111 arranged in a basically vertical manner, and the other layer (the lower layer in the figure) is columns 111 arranged in an inclined manner.

[0100] Regarding the above tilt, based on Figure 5 A more detailed explanation is given. Figure 5 The stereoscopic diagram of FIG. 1 is a diagram in which, for the purpose of explanation, only one of the regions 111 with a relatively high refractive index that originally exist in the light diffusion control layer 11 is retained and the others are omitted. Figure 5 In the region 111 with a relatively high refractive index, Figure 5 The straight line extends from the lower side to the upper side, and a straight line parallel to the extending direction (direction A) is inclined at an angle a with respect to the thickness direction (direction B) of the light diffusion control layer 11 .

[0101] In addition, when the region (column) 111 with relatively high refractive index is bent as described later, the above-mentioned extension direction (direction A) refers to the direction in which the column extends from the bending portion to one end, and in particular, refers to the direction in which the column extends from the bending portion to one end on the visual observer side.

[0102] Furthermore, in the light diffusion control members 1a and 1b of the present embodiment, the angle a is preferably greater than 0°, particularly preferably greater than 1°, and further preferably greater than 2°. By being in such a range, the display content can be displayed more brightly. In addition, the angle a is preferably less than 30°, more preferably less than 15°, particularly preferably less than 8°, and further preferably less than 5°. By being in such a range, the difference in brightness can be further reduced when the up and down directions of the display content are changed. In addition, the angle a can be measured by observing the cross section of the light diffusion control layer 11 using an optical digital microscope.

[0103] In the light diffusion control layer 11 of the present embodiment, from the viewpoint of easily satisfying the above-mentioned conditions of L1, L2, and L3, it is preferred that the pillars 111 bend between one end and the other end in at least one layer of the layer formed of the columnar structure. Figure 4 The column structure shown in (a) is an example of a column structure having such a curved columnar object 111. Figure 4 In the column structure shown in (b), bending of the columnar object 111 also occurs in the lower layer.

[0104] Furthermore, from the perspective of easily satisfying the above-mentioned conditions of L1, L2 and L3, the light diffusion control layer 11 of this embodiment preferably has two layers formed of column structures. Figure 4 The column structure shown in (b) is preferably a stack of two layers formed by a forest of columnar objects 111. In this case, the inclination or curvature of each layer can be the same or different between the two layers. Preferably, Figure 4 The column structure shown in (b) is composed of two layers: layer 1 formed by columns arranged in a manner basically parallel to the thickness direction of the light diffusion control layer (that is, basically perpendicular to the main surface of the light diffusion control layer), and layer 2 formed by columns inclined relative to the thickness direction of the light diffusion control layer and bent in the extending direction. Furthermore, it is particularly preferred that layer 1 of layer 1 and layer 2 is arranged on the visual identifier side.

[0105] In the above columnar structure, the difference between the refractive index of the region 111 (columnar object) with a relatively high refractive index and the refractive index of the region 112 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. Thus, 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. In addition, the refractive index when calculating the above difference refers to the refractive index measured for each of the cured products obtained by separately curing the materials of the region 111 with a relatively high refractive index and the region 112 with a relatively low refractive index. In addition, the material described herein refers to, in addition to the high refractive index component and the low refractive index component as necessary components, other additives such as the above-mentioned photopolymerization initiator or ultraviolet absorber may be included as needed. In addition, when other additives are used, their content or specific examples may be as described above.

[0106] The above-mentioned columnar object preferably has a structure in which the diameter increases from one surface to the other surface of the light diffusion control layer 11. Compared with a columnar object whose diameter is substantially constant from one surface to the other surface, a columnar object having such a structure is more likely to change the traveling direction of light parallel to the extending direction of the columnar object. Thus, the light diffusion control layer 11 can effectively diffuse light.

[0107] In addition, the maximum value of the diameter of the cross section when the column is cut in the extending direction by a horizontal plane is preferably 0.1 to 15 μm, particularly preferably 0.5 to 10 μm, and further preferably 1 to 5 μm. By having the maximum value of the diameter in the above range, the light diffusion control layer 11 can effectively diffuse light. In addition, there is no particular limitation on the cross-sectional shape when the column is cut in a plane perpendicular to the extending direction, and it is preferably, for example, a circle, an ellipse, a polygon, a deformed shape, etc.

[0108] In the above columnar structure, the distance between adjacent columns is preferably 0.1 to 15 μm, particularly preferably 0.5 to 10 μm, and further preferably 1 to 5 μm. When the distance between adjacent columns is within the above range, the light diffusion control layer 11 can effectively diffuse light.

[0109] In addition, the dimensions and the like of the regular internal structure of the above-mentioned columnar structure can be measured by observing a cross section of the columnar structure using an optical digital microscope.

[0110] (6) Thickness of light diffusion control layer

[0111] The thickness of the light diffusion control layer 11 is preferably 1 to 500 μm, more preferably 10 to 300 μm, particularly preferably 30 to 200 μm, further preferably 50 to 150 μm, preferably 70 to 130 μm, and most preferably 80 to 115 μm. By having the thickness in the above range, the above conditions of L1, L2, and L3 can be easily satisfied. In addition, image blurring or a decrease in total transmittance can be prevented.

[0112] In addition, when the light diffusion control layer 11 is Figure 4 When the two-layer stacking structure shown in (b) is formed, the overall thickness of the two layers is preferably 1 to 500 μm, more preferably 50 to 400 μm, particularly preferably 100 to 300 μm, and further preferably 150 to 250 μm. In addition, in the above-mentioned two layers, the thickness of the layer arranged on the visual identifier side is preferably 1 to 300 μm, more preferably 25 to 200 μm, and particularly preferably 50 to 150 μm. In addition, in the above-mentioned two layers, the thickness of the layer arranged on the opposite side to the visual identifier is preferably 1 to 300 μm, more preferably 25 to 200 μm, and particularly preferably 50 to 150 μm. From the perspective of easily satisfying the above-mentioned conditions of L1, L2 and L3, it is preferred to satisfy the above-mentioned thickness range.

[0113] 2. Diffusion adhesive layer

[0114] The diffusion adhesive layer 12 of the present embodiment is not particularly limited as long as it contains light diffusing particles. The adhesive constituting the diffusion adhesive layer 12 is not particularly limited, and for example, it can be any one of acrylic adhesive, polyester adhesive, polyurethane adhesive, rubber adhesive, silicone adhesive, etc. In addition, the adhesive can be any one of emulsion type, solvent type or solvent-free type, and can be any one of cross-linked type or non-cross-linked type. Among them, acrylic adhesives with excellent adhesive properties, optical properties, etc. are preferred. As acrylic adhesives, cross-linked adhesives are preferred, and thermal cross-linked adhesives are further preferred.

[0115] When the diffusion adhesive layer 12 of the present embodiment is composed of an acrylic adhesive, the adhesive is preferably an adhesive formed by cross-linking a diffusion adhesive layer forming composition containing a (meth)acrylate polymer, a cross-linking agent, and light diffusion particles. In addition, in this specification, "polymer" also includes the concept of "copolymer".

[0116] (1) Components of the Diffusion Adhesive Layer-Forming Composition

[0117] (1-1) (Meth)acrylate polymer

[0118] The (meth)acrylate polymer in this embodiment preferably contains a reactive group-containing monomer having a reactive group that reacts with a crosslinking agent in the molecule as a monomer unit constituting the polymer. The reactive group from the reactive group-containing monomer reacts with the crosslinking agent to form a crosslinked structure (three-dimensional network structure), and an adhesive having a desired cohesive force can be obtained.

[0119] Preferred examples of the reactive group-containing monomer include monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomers), monomers having a carboxyl group in the molecule (carboxyl group-containing monomers), monomers having an amino group in the molecule (amino group-containing monomers), etc. Among them, hydroxyl group-containing monomers having excellent reactivity with a crosslinking agent are preferred.

[0120] As the hydroxyl-containing monomer, for example, preferably, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and the like (meth)acrylate hydroxyalkyl esters and the like can be listed. Among them, from the perspective of the reactivity of the hydroxyl group in the obtained (meth)acrylate polymer with the crosslinking agent and the copolymerizability with other monomers, preferably, a (meth)acrylate hydroxyalkyl ester having a hydroxyalkyl group with 1 to 4 carbon atoms is used. Specifically, preferably, for example, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and the like. These can be used alone or in combination of two or more.

[0121] The (meth)acrylate polymer preferably contains 1 to 50% by mass of a reactive group-containing monomer as a monomer unit constituting the polymer, more preferably 7 to 45% by mass, particularly preferably 13 to 40% by mass, further preferably 18 to 35% by mass, and preferably 22 to 30% by mass. Thus, a good cross-linked structure is easily formed in the obtained adhesive, and there is a tendency to improve the dispersibility of the light diffusion particles in the adhesive.

[0122] The (meth)acrylate polymer preferably contains an alkyl (meth)acrylate as a monomer unit constituting the polymer. This can exhibit good adhesiveness. The alkyl group may be linear or branched.

[0123] As the (meth)acrylic acid alkyl ester, from the perspective of adhesion, it is preferably an (meth)acrylic acid alkyl ester having an alkyl carbon number of 1 to 20, and preferably includes, for example, 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, stearic (meth)acrylate, etc. Among them, from the perspective of further improving adhesion, it is preferably an (meth)acrylic acid alkyl ester having an alkyl carbon number of 4 to 8, and n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or isooctyl (meth)acrylate is particularly preferred. In addition, these can be used alone or in combination of two or more.

[0124] (Meth) acrylate polymer, as the monomer unit constituting the polymer, preferably contains 20~99 mass % of (meth) alkyl acrylate, more preferably contains 30~90 mass %, particularly preferably contains 40~80 mass %, further preferably contains 45~70 mass %. Thus, the obtained adhesive can exert appropriate adhesion. In addition, there is a tendency that the dispersibility of light diffusion particles in the adhesive becomes good, and it is easy to exert the desired light diffusion without damaging the desired adhesion. In addition, other monomer components such as reactive functional group-containing monomers can be introduced in a suitable amount in the (meth) acrylate polymer.

[0125] The (meth)acrylate polymer preferably contains a monomer having an alicyclic structure in the molecule (alicyclic structure-containing monomer) as a monomer unit constituting the polymer. Since the alicyclic structure-containing monomer is large in volume, the spacing between the polymers can be expanded by making these monomers exist in the polymer, which can have a tendency to reduce the viscosity of the coating liquid and improve the dispersibility of the light-diffusing particles in the adhesive.

[0126] The carbon ring of the alicyclic structure in the alicyclic structure-containing monomer may be a saturated structure or a structure having a portion of unsaturated bonds. In addition, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure. From the above-mentioned perspective, polycyclic alicyclic structures (polycyclic structures) are preferred, and polycyclic structures of two to four rings are particularly preferred. In addition, from the above-mentioned perspective, the number of carbon atoms in the alicyclic structure (referring to the total number of carbon atoms forming the ring, when multiple rings exist independently, it refers to the total number of carbon atoms) is preferably 5 to 15, and particularly preferably 7 to 10.

[0127] As the monomer containing alicyclic structure, specifically, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, etc. can be listed. Among them, from the perspective of exerting the dispersibility of light-diffusing particles in the adhesive or excellent adhesion, dicyclopentanyl (meth)acrylate (the number of carbon atoms in the alicyclic structure: 10), adamantyl (meth)acrylate (the number of carbon atoms in the alicyclic structure: 10) or isobornyl (meth)acrylate (the number of carbon atoms in the alicyclic structure: 7) is preferred, and isobornyl (meth)acrylate is particularly preferred. These can be used alone or in combination of two or more.

[0128] When the (meth)acrylate polymer contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, it is preferred that the alicyclic structure-containing monomer be contained in an amount of 1 to 20% by mass, particularly preferably 5 to 15% by mass, and further preferably 7 to 12% by mass. This allows the dispersibility of the light-diffusing particles in the adhesive to be improved, and the resulting adhesive can exhibit desired light diffusivity.

[0129] The (meth)acrylate polymer preferably contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. By allowing the nitrogen atom-containing monomer to exist in the polymer as a structural unit, the adhesive can be given a specified polarity, and has excellent affinity for adherends with a certain degree of polarity such as glass. As the nitrogen atom-containing monomer, from the perspective of giving the (meth)acrylate polymer moderate rigidity, a monomer having a nitrogen-containing heterocycle is preferred. In addition, from the perspective of increasing the degree of freedom from the nitrogen atom-containing monomer part in the high-order structure of the constructed adhesive, the nitrogen atom-containing monomer preferably does not contain a reactive unsaturated double bond group except for one polymerizable group used in the polymerization for forming the (meth)acrylate polymer.

[0130] As the monomer with nitrogen-containing heterocycle, for example, N-(methyl)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(methyl)acryloylpyrrolidone, N-(methyl)acryloylpiperidine, N-(methyl)acryloylpyrrolidine, N-(methyl)acryloylaziridine, aziridine-based ethyl (methyl)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. can be listed. Among them, from the perspective of giving play to the dispersibility of light diffusion particles in the adhesive or excellent adhesion, N-(methyl)acryloylmorpholine is preferred. These can be used alone or in combination of two or more.

[0131] When the (meth)acrylate polymer contains a nitrogen-containing monomer as a monomer unit constituting the polymer, it is preferred to contain 1 to 20% by mass of the nitrogen-containing monomer, particularly preferably 3 to 16% by mass, and further preferably 5 to 12% by mass. Thus, the resulting adhesive can fully exert excellent adhesion to glass or metal film. In addition, the dispersibility of the light-diffusing particles in the adhesive can be improved, and the resulting adhesive can exert desired light diffusivity.

[0132] As required, the (meth)acrylate polymer may contain other monomers as monomer units constituting the polymer. As other monomers, in order not to hinder the above-mentioned effects of the monomer containing reactive functional groups, preferably monomers without reactive functional groups. As such monomers, for example, (meth)acrylate methoxyethyl, (meth)acrylate ethoxyethyl, (meth)acrylate alkoxyalkyl (meth)acrylate, vinyl acetate, styrene, etc. can be cited. These can be used alone or in combination of two or more.

[0133] The (meth)acrylate polymer is preferably a straight-chain polymer, because this facilitates entanglement of molecular chains, and can be expected to improve cohesive force, thereby making it easy to obtain an adhesive having excellent adhesiveness and durability.

[0134] The (meth)acrylate polymer is preferably a solution polymer obtained by a solution polymerization method, because a high molecular weight polymer can be easily obtained, and it is expected that the cohesive force can be improved, and an adhesive having excellent adhesiveness and durability can be easily obtained.

[0135] The polymerization form of the (meth)acrylate polymer may be a random copolymer or a block copolymer.

[0136] The weight average molecular weight of the (meth)acrylate polymer is preferably 200,000 to 2,000,000, more preferably 300,000 to 1,500,000, particularly preferably 400,000 to 1,000,000, and further preferably 500,000 to 700,000. This can improve the dispersibility of the light-diffusing particles in the adhesive, and the obtained adhesive can exhibit the desired light diffusivity and good adhesion.

[0137] In the diffusion adhesive layer-forming composition, the (meth)acrylate polymer may be used alone or in combination of two or more.

[0138] (1-2) Cross-linking agent

[0139] As a crosslinking agent, as long as it is a crosslinking agent that reacts with the reactive group possessed by the (meth) acrylate polymer, for example, isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, hydrazine crosslinking agents, acetal crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, ammonium salt crosslinking agents, etc. can be listed. Among the above, it is preferred to use an isocyanate crosslinking agent with excellent reactivity with a hydroxyl group. In addition, a crosslinking agent can be used alone, or two or more can be used in combination.

[0140] Isocyanate crosslinking agents include at least polyisocyanate compounds, such as aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the like, as well as adducts of their biuret bodies and isocyanurate bodies, and reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil, etc. Among them, trimethylolpropane-modified aromatic polyisocyanates are preferred from the viewpoint of reactivity with hydroxyl groups, and trimethylolpropane-modified toluene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are particularly preferred.

[0141] The content of the crosslinking agent in the diffusion adhesive layer forming composition is preferably 0.01 to 10 parts by mass, more preferably 0.04 to 5 parts by mass, particularly preferably 0.08 to 1 part by mass, and further preferably 0.1 to 0.4 parts by mass, relative to 100 parts by mass of the (meth)acrylate polymer. Thus, it is easy to make the cohesive force or adhesive force of the obtained adhesive appropriate.

[0142] (1-3) Light Diffusing Particles

[0143] As light-diffusing microparticles (C), inorganic microparticles such as silicon dioxide, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, titanium dioxide, etc. can be listed; organic light-transmitting microparticles such as acrylic resin, polystyrene resin, polyethylene resin, epoxy resin, etc.; microparticles formed by silicon-containing compounds having an intermediate structure between inorganic and organic, such as silicone resins (for example, TOSPEARL series manufactured by Momentive Performance Materials Japan), etc. Among them, microparticles formed by silicon-containing compounds having an intermediate structure between inorganic and organic are preferred. In particular, from the perspective of easily satisfying the above-mentioned conditions of L1, L2 and L3, microparticles formed by silicon-containing compounds having an intermediate structure between inorganic and organic and titanium dioxide are preferred. Furthermore, from the perspective of suppressing backscattering, microparticles formed by silicon-containing compounds having an intermediate structure between inorganic and organic are preferred. The above light-diffusing microparticles can be used alone or in combination of two or more.

[0144] The shape of the light diffusion particles may be either shaped or amorphous, but from the perspective of obtaining a uniform light diffusion diffusion adhesive layer that can easily exert the desired optical performance, shaped particles are preferred, spherical particles are particularly preferred, and true spherical particles are further preferred. Thus, the obtained diffusion adhesive layer easily exerts the desired light diffusivity and easily satisfies the above-mentioned conditions of L1, L2, and L3. In addition, it is not easy to produce light loss due to backscattering, and good image quality can be provided.

[0145] The average particle size of the light diffusion particles based on the centrifugal sedimentation light transmission method is preferably 0.1 to 20.0 μm, more preferably 0.2 to 15.0 μm, and from the perspective of suppressing backscattering, it is preferably 0.5 to 10.0 μm, particularly preferably 3.0 to 6.0 μm, and further preferably 4.0 to 5.0 μm. Thus, the obtained diffusion adhesive layer is easy to exert the desired light diffusion and is easy to meet the above-mentioned conditions of L1, L2 and L3. In particular, it is not easy to produce light loss due to backscattering and can provide good image quality.

[0146] The average particle size based on the centrifugal sedimentation light transmission method is measured as follows: 1.2 g of microparticles and 98.8 g of isopropyl alcohol are thoroughly stirred as a test sample and measured using a centrifugal automatic particle size distribution measuring device (manufactured by HORIBA, Ltd., CAPA-700).

[0147] In addition, regarding the average particle size of the light diffusion particles, when the light diffusion particles are so-called nanoparticles and are difficult to measure in the above-mentioned centrifugal sedimentation light transmission method, the average particle size refers to that measured by the laser diffraction scattering method. In this case, the average particle size of the light diffusion particles based on the laser diffraction scattering method is preferably 10 to 1000 nm, particularly preferably 100 to 600 nm, and further preferably 200 to 400 nm. Thus, the obtained diffusion adhesive layer is easy to exert the desired light diffusivity and is easy to meet the above-mentioned conditions of L1, L2 and L3.

[0148] Relative to 100 parts by mass of the above-mentioned (meth) acrylate polymer, the content of the light diffusion particles in the diffusion adhesive layer formation composition is preferably 0.1 to 50 parts by mass, more preferably 0.4 to 40 parts by mass, particularly preferably 1 to 30 parts by mass, further preferably 5 to 22 parts by mass, wherein preferably 10 to 16 parts by mass. Thus, the diffusion adhesive layer obtained easily exerts the desired light diffusivity, and easily satisfies the conditions of the above-mentioned L1, L2 and L3. In addition, it is not easy to produce the light loss caused by backscattering and can provide good image quality. Further, it is possible to exert the desired light diffusivity, and easily exert excellent durability.

[0149] (1-4) Other ingredients

[0150] The diffusion adhesive layer is formed with a composition as required, and can contain the composition except the above-mentioned (methyl) acrylate polymer, cross-linking agent and light diffusion particles. For example, from the perspective of giving active energy ray curing to the obtained adhesive, the composition can contain active energy ray curing components. In this case, from the perspective of effectively carrying out the curing based on active energy rays, preferably containing a photopolymerization initiator. In addition, the diffusion adhesive layer is formed with a composition and can add various commonly used additives in acrylic adhesives, such as silane coupling agents, rust inhibitors, ultraviolet light absorbers, infrared absorbers, colorants, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, refractive index regulators, etc. In addition, the polymerization solvent and dilution solvent described later are not included in the additive constituting the diffusion adhesive layer forming composition.

[0151] The diffusion adhesive layer is formed with a composition, preferably containing the above-mentioned silane coupling agent. Thus, even if the adherend is a plastic plate, a glass component, or a metal film, the adhesion to the adherend can also be improved, and the durability is excellent. As the silane coupling agent, it is preferred that the organosilicon compound having at least one alkoxysilyl group in the molecule and the compound having good compatibility with the (meth) acrylate polymer and having light transmittance.

[0152] As the silane coupling agent, preferably, for example, condensates with silicon compounds containing polymerizable unsaturated groups, silicon compounds having epoxy structures, silicon compounds containing mercapto groups, silicon compounds containing amino groups, and silicon compounds containing alkyl groups can be listed. Among them, from the perspective of not damaging the desired light diffusivity and easily satisfying the above-mentioned conditions of L1, L2 and L3, and at the same time improving the durability, silicon compounds having epoxy structures are preferred, and 3-glycidyloxypropyltrimethoxysilane is particularly preferred. These can be used alone or in combination of two or more.

[0153] The content of the silane coupling agent in the diffusion adhesive layer forming composition is preferably 0.01 to 2 parts by mass, more preferably 0.05 to 1.5 parts by mass, particularly preferably 0.1 to 1 part by mass, and further preferably 0.2 to 0.5 parts by mass relative to 100 parts by mass of the (meth)acrylate polymer. Thus, the obtained diffusion adhesive layer can easily satisfy the above-mentioned conditions of L1, L2 and L3 without damaging the desired light diffusivity, and can easily improve durability.

[0154] (2) Preparation of Composition for Forming Diffusion Adhesive Layer

[0155] The diffusion adhesive layer-forming composition can be produced by preparing a (meth)acrylate polymer, mixing the obtained (meth)acrylate polymer, a crosslinking agent, and light-diffusing fine particles, and adding other components as necessary.

[0156] (Meth) acrylate polymers can be manufactured by polymerizing a mixture of monomers constituting the polymer by a conventional free radical polymerization method. The polymerization is preferably carried out by a solution polymerization method using a polymerization initiator as required. However, the present invention is not limited thereto, and polymerization can also be carried out in the absence of a solvent. As polymerization solvents, for example, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc. can be listed, and one can be used alone or two or more can be used at the same time. As polymerization initiators, azo compounds, organic peroxides, etc. can be listed, and one can be used alone or two or more can be used at the same time. In addition, in the above-mentioned polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by blending a chain transfer agent such as 2-mercaptoethanol.

[0157] After obtaining the (meth)acrylate polymer, a crosslinking agent, light diffusion particles, and other components as needed are added to the solution of the polymer and fully mixed to obtain a composition for forming a diffusion adhesive layer (coating solution) diluted with a solvent. In addition, in any of the above-mentioned components, when a solid substance is used, or, in the case of precipitation when mixed with other components in an undiluted state, the component can also be separately dissolved or diluted in a diluting solvent in advance and then mixed with other components.

[0158] As the diluting solvent, for example, aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and dichloroethane; 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 melting agent solvents such as ethyl melting agent.

[0159] As the concentration and viscosity of the prepared coating solution, there is no particular restriction, and can be appropriately selected in the scope of coating according to the situation.For example, the concentration of the diffusion adhesive layer forming composition is diluted in a manner of 10~60 mass %.In addition, when obtaining the coating solution, the addition of diluting solvent etc. is not a necessary condition, as long as the diffusion adhesive layer forming composition is a coating viscosity etc., it is also possible not to add diluting solvent.At this point, the diffusion adhesive layer forming composition is a coating solution that directly uses the polymerization solvent of (methyl) acrylate polymer as a diluting solvent.

[0160] (3) Thickness of diffusion adhesive layer

[0161] The thickness of the diffusion adhesive layer 12 is preferably 1 to 500 μm, more preferably 10 to 300 μm, particularly preferably 20 to 100 μm, further preferably 30 to 75 μm, preferably 38 to 55 μm, and most preferably 42 to 48 μm. By having the thickness in the above range, the above-mentioned conditions of L1, L2 and L3 can be easily satisfied. In addition, blurring of the image or a decrease in the total light transmittance can be prevented. Further, good durability can be exerted.

[0162] The haze value of diffusion adhesive layer 12 is preferably 20-100%, more preferably 40-96%, particularly preferably 60-92%, further preferably 70-90%, wherein, preferably 80-88%. By this haze value in the above-mentioned range, it is easy to meet the conditions of above-mentioned L1, L2 and L3. In addition, it is not easy to produce the light loss caused by backscattering and can provide good image quality. In addition, the haze value in this manual is the value measured as described in the test example later.

[0163] 3. Middle adhesive layer

[0164] Figure 2 The light diffusion control member 1b shown has an intermediate adhesive layer 13. The intermediate adhesive layer 13 is sufficiently adhered to the light diffusion control layer 11 and the diffusion adhesive layer 12, and can suppress the peeling or displacement of these layers. As a result, the durability of the light diffusion control member 1b having the intermediate adhesive layer 13 becomes excellent. From the perspective of more easily achieving excellent durability, the intermediate adhesive layer 13 is preferably composed of a carboxyl-containing adhesive.

[0165] The adhesive constituting the intermediate adhesive layer 13 is not particularly limited, and may be, for example, any one of an acrylic adhesive, a polyester adhesive, a polyurethane adhesive, a rubber adhesive, a silicone adhesive, etc. In addition, the adhesive may be any one of an emulsion type, a solvent type, or a solvent-free type, and may be any one of a cross-linked type or a non-cross-linked type. Among them, an acrylic adhesive having excellent adhesive properties, optical properties, etc. is preferred. As the acrylic adhesive, a cross-linked type is preferred, and a thermal cross-linked type is further preferred.

[0166] When the intermediate adhesive layer 13 of the present embodiment is composed of an acrylic adhesive, the adhesive is preferably obtained by cross-linking an intermediate adhesive layer-forming composition containing a (meth)acrylate polymer and a cross-linking agent.

[0167] The (meth)acrylate polymer may be the same as or different from the (meth)acrylate polymer used to form the diffusion adhesive layer 12. From the perspective of achieving excellent durability by sufficiently adhering to the light diffusion control layer 11 and the diffusion adhesive layer 12, the (meth)acrylate polymer in the intermediate adhesive layer 13 preferably contains a carboxyl group-containing monomer as a monomer unit constituting the polymer.

[0168] Examples of carboxyl-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Of these, acrylic acid is preferred from the perspective of the reactivity of the carboxyl group in the obtained (meth)acrylate polymer with a crosslinking agent and copolymerizability with other monomers. These may be used alone or in combination of two or more.

[0169] The (meth)acrylate polymer in the intermediate adhesive layer 13 preferably contains 1 to 30% by mass of a carboxyl group-containing monomer as a monomer unit constituting the polymer, more preferably 3 to 24% by mass, particularly preferably 6 to 18% by mass, and further preferably 9 to 12% by mass. Thus, the intermediate adhesive layer 13 obtained is sufficiently adhered to the light diffusion control layer 11 and the diffusion adhesive layer 12, and is easy to achieve excellent durability.

[0170] The (meth)acrylate polymer in the intermediate adhesive layer 13 preferably contains an alkyl (meth)acrylate as a monomer unit constituting the polymer. As the alkyl (meth)acrylate, the same alkyl (meth)acrylate as that used to form the diffusion adhesive layer 12 can be used.

[0171] The (meth)acrylate polymer in the intermediate adhesive layer 13 preferably contains 70 to 99% by mass of an alkyl (meth)acrylate as a monomer unit constituting the polymer, more preferably 76 to 97% by mass, particularly preferably 82 to 94% by mass, and further preferably 88 to 91% by mass. Thus, the intermediate adhesive layer 13 obtained exhibits good adhesion and easily achieves excellent durability.

[0172] The weight average molecular weight of the (meth)acrylate polymer used in the intermediate adhesive layer 13 is preferably 100,000 to 2,000,000, more preferably 200,000 to 1,200,000, particularly preferably 300,000 to 800,000, and further preferably 350,000 to 500,000. Thus, the intermediate adhesive layer 13 obtained exhibits good adhesion and easily achieves excellent durability.

[0173] The crosslinking agent of the intermediate adhesive layer 13 is the same as the crosslinking agent used to form the diffusion adhesive layer 12, and any substance that reacts with the reactive group possessed by the (meth)acrylate polymer can be used, and the same substances can be exemplified. Among them, it is preferred to use an epoxy crosslinking agent with excellent reactivity with a carboxyl group. In addition, the crosslinking agent can be used alone or in combination of two or more.

[0174] 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, diglycidyl aniline, and diglycidylamine. Among them, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is preferred from the viewpoint of reactivity with carboxyl groups.

[0175] The content of the crosslinking agent in the intermediate adhesive layer-forming composition is preferably 0.001 to 10 parts by mass, more preferably 0.005 to 1 part by mass, particularly preferably 0.01 to 0.5 parts by mass, and further preferably 0.02 to 0.1 parts by mass, relative to 100 parts by mass of the (meth)acrylate polymer. Thus, the intermediate adhesive layer 13 obtained exhibits good cohesive force and adhesion, and is easy to achieve excellent durability.

[0176] In addition to the above-mentioned (meth) acrylate polymer and cross-linking agent, the intermediate adhesive layer forming composition can also contain other components. As the example of these other components, the above-mentioned components that can be added to the diffusion adhesive layer forming composition can be listed. In addition, the intermediate adhesive layer forming composition, from the perspective of easily realizing excellent durability, preferably does not contain light diffusion particles.

[0177] The intermediate adhesive layer forming composition can be prepared in the same manner as the diffusion adhesive layer forming composition. In addition, the (meth) acrylate polymer contained in the intermediate adhesive layer forming composition can also be prepared in the same manner as the (meth) acrylate polymer contained in the diffusion adhesive layer forming composition.

[0178] The thickness of the intermediate adhesive layer 13 is preferably 1 to 300 μm, more preferably 4 to 100 μm, particularly preferably 8 to 60 μm, further preferably 10 to 30 μm, and preferably 12 to 20 μm. By having this thickness in the above range, the light diffusion control layer 11 and the diffusion adhesive layer 12 are fully adhered, and excellent durability is easily achieved. In addition, the thickness of the intermediate adhesive layer 13 is preferably thinner than the thickness of the light diffusion control layer 11 or the thickness of the diffusion adhesive layer 12, and particularly preferably thinner than the thickness of any layer. Thus, while exerting excellent durability, it is easy to exert the optical properties of the light diffusion control layer 11 and the diffusion adhesive layer 12, and it is easy to meet the above-mentioned conditions of L1, L2 and L3.

[0179] 4. Other requirements

[0180] The light diffusion control members 1a and 1b of the present embodiment may also include elements other than the above-mentioned light diffusion control layer 11, diffusion adhesive layer 12, and intermediate adhesive layer 13. For example, the light diffusion control members 1a and 1b of the present embodiment include a release sheet on the surface on the diffusion adhesive layer 12 side. The release sheet protects the surface (adhesive surface) of the diffusion adhesive layer 12 located on the opposite side to the light diffusion control layer 11 until the surface is attached to a predetermined object.

[0181] As the release sheet, resin films such as polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ion polymer resin film, ethylene-(methyl) acrylic acid copolymer film, ethylene-(methyl) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film can be used. In addition, crosslinked films of these films can also be used. Further, laminated films of these films can also be used.

[0182] The release surface of the release sheet is preferably subjected to a release treatment. Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

[0183] The thickness of the release sheet is not particularly limited, but is preferably 20 to 200 μm, more preferably 30 to 100 μm, from the viewpoint of excellent handling properties.

[0184] In addition, for example, the light diffusion control members 1a and 1b of the present embodiment may further include a process sheet on the surface on the light diffusion control layer 11 side. The process sheet is used not only for coating the light diffusion control layer composition to form the light diffusion control layer 11, but also for protecting the surface of the light diffusion control layer 11 on the side opposite to the diffusion adhesive layer 12 until the process sheet is peeled off.

[0185] As the processing sheet, the resin film, crosslinked film, or laminated film thereof used as the release sheet can be used. In this embodiment, the release sheet can also be used as the processing sheet, which is preferred from the viewpoint of easily forming the desired light diffusion control layer 11.

[0186] From the viewpoint of facilitating the formation of a desired light diffusion control layer 11 and of being able to well protect the light diffusion control layer 11 until use, the thickness of the processed sheet is preferably 20 to 250 μm, more preferably 30 to 200 μm.

[0187] In addition, the light diffusion control members 1a and 1b of the present embodiment may also be configured such that an intermediate adhesive layer is provided on the surface of the light diffusion control layer 11 on the side opposite to the diffusion adhesive layer 12. That is, the light diffusion control members 1a and 1b of the present embodiment may have a layer configuration of intermediate adhesive layer / light diffusion control layer 11 / diffusion adhesive layer 12, or a layer configuration of intermediate adhesive layer / light diffusion control layer 11 / intermediate adhesive layer 13 / diffusion adhesive layer 12.

[0188] The light diffusion control members 1a and 1b having the above-mentioned layer structure are suitable for manufacturing a reflective display 100 in which the surface on the light diffusion control layer 11 side is laminated on the display device 2 and the reflective layer 3. In the reflective display 100, the surface on the light diffusion control layer 11 side of the light diffusion control members 1a and 1b can be sufficiently fixed to the display device 2 or the reflective layer 3 via the intermediate adhesive layer.

[0189] The intermediate adhesive layer provided on the surface of the light diffusion control layer 11 opposite to the diffusion adhesive layer 12 may be the same layer as the intermediate adhesive layer 13 provided between the light diffusion control layer 11 and the diffusion adhesive layer 12 .

[0190] 5. Method for manufacturing light diffusion control member

[0191] The manufacturing method of the light diffusion control members 1a and 1b of the present embodiment is not particularly limited, and they can be manufactured by conventional manufacturing methods. For example, the light diffusion control layer 11 and the diffusion adhesive layer 12 and the intermediate adhesive layer 13 can be prepared as needed, and then the light diffusion control layer 11, the diffusion adhesive layer 12 and the intermediate adhesive layer 13 can be appropriately stacked to obtain the light diffusion control members 1a and 1b.

[0192] The method for forming the light diffusion control layer 11 is not particularly limited, and the light diffusion control layer 11 can be formed by a conventionally known method.

[0193] For example, the composition for the light diffusion control layer is applied to one surface of the processing sheet to form a coating film, and then one surface (particularly the release surface) of the release sheet is attached to the surface of the coating film opposite to the processing sheet. Then, the coating film is irradiated with active energy rays through the processing sheet or the release sheet to cure it, thereby forming the light diffusion control layer 11. In this way, by laminating the release sheet on the coating film, the interval between the release sheet and the processing sheet can be maintained to prevent the coating film from being crushed, and the light diffusion control layer 11 with uniform thickness and a desired regular internal structure can be easily formed.

[0194] In addition, for example, the composition for the light diffusion control layer is applied to one surface of a processing sheet to form a coating film, and then the coating film is irradiated with active energy rays for a first time to perform primary curing, and then one surface of a release sheet is attached to the surface of the coating film opposite to the processing sheet. Furthermore, the coating film is irradiated with active energy rays for a second time through the processing sheet or the release sheet to perform secondary curing, thereby forming the light diffusion control layer 11. In this way, by irradiating active energy rays in two stages to perform curing, it is easy to form a light diffusion control layer 11. Figure 4 The light diffusion control layer 11 shown in (b) is a two-layer stacked layer.

[0195] Examples of the coating method include knife coating, roll coating, bar coating, doctor blade coating, die coating, and gravure coating. The light diffusion control layer composition may be diluted with a solvent as necessary.

[0196] The active energy ray irradiation of the coating film can be carried out in different ways according to the regular internal structure to be formed. The irradiation can be carried out by a conventionally known method. For example, when forming the above-mentioned columnar structure, the coating film is irradiated with parallel light with high light parallelism.

[0197] The active energy rays are rays having energy quanta among electromagnetic waves or charged particle beams, 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 and can easily form a desired regular internal structure.

[0198] When ultraviolet rays are used as active energy rays to form a column structure, the irradiation conditions are preferably such that the peak illuminance on the coating surface is 0.1 to 10 mW / cm 2 In addition, the peak illuminance here refers to the measured value of the portion where the active energy rays irradiated on 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 .

[0199] In addition, from the perspective of achieving more reliable curing, it is preferred to irradiate with normal active energy rays (active energy rays that are not converted into parallel light or band light, scattered light) after curing using the above-mentioned parallel light or band light.

[0200] About the formation method of diffusion adhesive layer 12 and intermediate adhesive layer 13, each is not particularly limited, and can be formed by a known method in the past. For example, it can be formed by making the diffusion adhesive layer forming composition and the intermediate adhesive layer forming composition (coating layer) crosslinked. The crosslinking of these compositions can usually be carried out by heat treatment. In addition, heat treatment also takes into account the drying process when the diluting solvent etc. are volatilized from the coating layer of the composition applied on the desired object.

[0201] The heating temperature of the heat treatment is preferably 50 to 150° C., and particularly preferably 70 to 120° C. The heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

[0202] After the heat treatment, a 1-2 week aging period at room temperature (e.g., 23° C., 50% RH) may be provided as required. When the aging period is required, the diffusion adhesive layer 12 or the intermediate adhesive layer 13 is formed after the aging period. When the aging period is not required, the diffusion adhesive layer 12 or the intermediate adhesive layer 13 is formed after the heat treatment is completed.

[0203] 6. Reflective display

[0204] As described above, the light diffusion control members 1a and 1b of this embodiment are suitable for use in the manufacture of the reflective display 100. The reflective display 100 preferably includes, for example, the light diffusion control members 1a and 1b described above; a display device 2 provided on any one side of the light diffusion control members 1a and 1b; and a reflective layer 3 provided on a side of the display device 2 opposite to the light diffusion control members 1a and 1b or assembled in the display device 2.

[0205] The reflective display 100 can achieve excellent visual recognition as described above by having the light diffusion control members 1a and 1b of this embodiment. In particular, even when the vertical direction of the display content is changed, a uniform brightness display can be achieved. Therefore, the reflective display 100 is preferably configured in a manner that the vertical direction of the display content on the display surface can be changed.

[0206] The shape of the display surface of the reflective display body 100 is not particularly limited, and it is typically preferred that the display surface has a rectangular shape. In this case, the display surface can be a rectangle formed by a pair of long sides and a pair of short sides, or a square with all sides having equal lengths. In addition, when the display surface is in such a rectangular shape, the up and down directions of the display content are preferably formed in a direction parallel to at least one side of the above-mentioned rectangle, and in a direction perpendicular to the direction at least. In addition, the shape of the display surface can also be a quadrilateral other than a rectangle such as a rhombus, a trapezoid, a parallelogram, a polygon other than a quadrilateral such as a triangle, a pentagon, a circle such as a perfect circle, an ellipse, and further an irregular shape other than these.

[0207] (1) Display device

[0208] The display device 2 is not particularly limited, and may be a display device installed in a common reflective display body. For example, the display device 2 may include a liquid crystal display, an organic EL display, an electronic paper, an electrophoretic display, a MEMS display, a solid-state crystal display, etc., and may also be a display in which a touch panel is further laminated on these displays.

[0209] (2) Reflective layer

[0210] The reflective layer 3 is not particularly limited, and may be a reflective layer used as a reflective layer of a common reflective display. As a preferred example of the reflective layer 3, a metal vapor-deposited film obtained by vapor-depositing a metal on a predetermined surface can be cited. As a preferred example of such a metal, aluminum, silver, nickel, etc. can be cited.

[0211] The thickness of the reflective layer 3 formed of a metal vapor-deposited film is not particularly limited, but is, for example, preferably 1 to 3000 nm, particularly preferably 10 to 1000 nm, and further preferably 50 to 400 nm from the viewpoint of exhibiting desired reflective characteristics.

[0212] The reflective layer 3 formed of a metal vapor-deposited film may be provided on the surface of a resin film as a support. As examples of such a resin film, the same resin film as exemplified as the above-mentioned release sheet may be used.

[0213] The reflective layer 3 may also be a reflective electrode. In this case, the reflective electrode may be assembled inside the display device 2, for example. Usually, the reflective electrode is not provided in a manner covering the entire display surface of the reflective display 100, but also exists in a portion where the electrode is not formed. Therefore, in the reflective display 100 having a reflective electrode, external light can be reflected by the reflective electrode, while light such as a backlight provided on the back of the display device 2 is transmitted through the portion where the electrode is not formed. The material of the reflective electrode as the reflective layer 3 is not particularly limited, and it can be formed by a common reflective electrode material.

[0214] In addition, in Figure 3 In the reflective display 100 shown in FIG. 1 , the reflective layer 3 is shown as a component independent of the display device 2. In addition, the reflective layer 3 is shown as existing in the entire lateral area (the entire area of ​​the surface of the display device 2 opposite to the light diffusion control member 1). However, the reflective display 100 of this embodiment is not limited to the above. Figure 3 As shown, it further includes a reflective display body having the above-mentioned reflective electrode as a reflective layer 3.

[0215] In addition, the reflective layer 3 may be a semi-transmissive and semi-reflective reflective layer that exhibits both the property of transmitting light and the property of reflecting light.

[0216] (3) Other components

[0217] The reflective display 100 may also include components other than the above-mentioned light diffusion control members 1a, 1b, the display device 2, and the reflective layer 3. For example, a surface coating layer, a cover panel, etc. may be provided on the side of the light diffusion control members 1a, 1b opposite to the display device 2. In addition, a backlight may be provided on the side of the display device 2 opposite to the light diffusion control members 1a, 1b.

[0218] (4) Method for manufacturing a reflective display

[0219] The manufacturing method of the reflective display 100 is not particularly limited, and the reflective display 100 can be manufactured by a conventional manufacturing method. Figure 3 In the case of the reflective display 100 shown, the light diffusion control members 1 a and 1 b , the display device 2 , and the reflective layer 3 are separately manufactured and then laminated to obtain the reflective display 100 .

[0220] The embodiments described above are described for easy understanding of the present invention and are not described for limiting the present invention. Therefore, the various elements disclosed in the embodiments described above also cover all design changes and equivalent technical solutions within the technical scope of the present invention.

[0221] For example, another layer may be provided between the light diffusion control layer and the diffusion adhesive layer, or on the surface of the light diffusion control layer on the opposite side to the diffusion adhesive layer.

[0222] In addition, in this specification, when "X to Y" (X and Y are arbitrary numbers) is recorded, unless otherwise specified, it includes the meaning of "X or more and Y or less", and also includes the meaning of "preferably greater than X" or "preferably less than Y". In addition, when "X or more" (X is an arbitrary number) is recorded, unless otherwise specified, it includes the meaning of "preferably greater than X", and when "Y or less" (Y is an arbitrary number) is recorded, unless otherwise specified, it includes the meaning of "preferably less than Y".

[0223] [Example]

[0224] Hereinafter, the present invention will be described in more detail with reference to Examples and the like; however, the scope of the present invention is not limited to these Examples and the like.

[0225] [Production Example 1] (Light Diffusion Control Layer A)

[0226] (1) Preparation of composition for light diffusion control layer

[0227] To 40 parts by mass (value calculated as solid content; the same applies hereinafter) of polyether urethane methacrylate having a weight average molecular weight of 9,900 obtained by reacting polypropylene glycol, isophorone diisocyanate and 2-hydroxyethyl methacrylate as a low refractive index component, 60 parts by mass of o-phenylphenoxyethoxyethyl acrylate having a molecular weight of 268 as a high refractive index component, 8 parts by mass of 2-hydroxy-2-methyl-1-phenylpropane-1-one as a photopolymerization initiator, and 0.08 parts by mass of a benzotriazole-based ultraviolet absorber (manufactured by BSF, product name "TINUVIN 384-2") as an ultraviolet absorber were added, and the mixture was heated and mixed under the condition of 80°C to obtain a composition for a light diffusion control layer.

[0228] (2) Formation of light diffusion control layer

[0229] The obtained composition for light diffusion control layer was applied to the release-treated surface of a release sheet (manufactured by LINTEC Corporation, product name "SP-PET188CL", thickness: 188 μm) of a long strip of polyethylene terephthalate sheet as a processed sheet, one side of which was subjected to release treatment with a silicone-based release agent, to form a coating film with a thickness of 110 μm. Next, the release-treated surface of a release sheet (manufactured by LINTEC Corporation, product name "SP-PLZ383030", thickness: 38 μm) of a polyethylene terephthalate sheet as a processed sheet was subjected to release treatment with a silicone-based release agent was laminated on the surface of the coating film on the opposite side to the processed sheet.

[0230] The laminate consisting of the peeling sheet, the coating film and the processed sheet obtained in the above manner is placed on a conveyor belt. At this time, the surface of the peeling sheet side of the laminate is made to be the upper side, and at the same time, the length direction of the laminate is made parallel to the conveying direction of the conveyor belt. In addition, with respect to the conveyor belt on which the laminate is placed, an ultraviolet point parallel light source (manufactured by JATEC Co., Ltd.) is set to control the parallelism of the central light within ±3°. At this time, the light source is set in a manner that can irradiate parallel light in a direction inclined 5° to the conveying direction of the conveyor belt relative to the normal direction of the surface on the coating film side of the laminate.

[0231] Then, the conveyor belt was operated to move the laminate, and the peak illuminance on the coating surface was 1.02 mW / cm 2 , the accumulated light intensity is 26.35mJ / cm 2 Under the conditions of , parallel light with a parallelism of less than 2° (ultraviolet rays from a high-pressure mercury lamp with a main peak wavelength of 365nm and other peaks at 254nm, 303nm, and 313nm) was irradiated to cure the coating film in the laminate, thereby forming a light diffusion control layer A with a thickness of 110μm. As a result, a laminated body in which a processed sheet, a light diffusion control layer A (thickness: 110μm), and a release sheet were sequentially laminated was obtained.

[0232] In addition, the peak illuminance and the accumulated light amount are measured by placing a UV METER with a light receiver (manufactured by EYE GRAPHICS COMPANY, product name "Eye UV Integrated Illuminance Meter UVPF-A1") at the position of the coating film. The thickness of the light diffusion control layer A is measured by using a constant pressure thickness meter (manufactured by Takara Seisakusho Co., Ltd., product name "Teclock PG-02J").

[0233] [Production Example 2] (Light Diffusion Control Layer B)

[0234] A laminated body in which the processed sheet, the light diffusion control layer B (thickness: 60 μm), and the release sheet were sequentially laminated was prepared in the same manner as in Preparation Example 1 except that the thickness of the light diffusion control layer was 60 μm.

[0235] [Production Example 3] (Light Diffusion Control Layer C)

[0236] A laminated body in which a processed sheet, a light diffusion control layer C (thickness: 110 μm) and a release sheet were sequentially laminated was prepared in the same manner as in Preparation Example 1 except that the irradiation angle of the parallel light irradiated from the ultraviolet spot parallel light source was changed to 10°.

[0237] [Production Example 4] (Light Diffusion Control Layer D)

[0238] A composition for a light diffusion control layer was obtained in the same manner as in step (1) of Preparation Example 1. The obtained composition for a light diffusion control layer was applied to the release-treated surface of a strip of a polyethylene terephthalate sheet (manufactured by LINTEC Corporation, product name "SP-PET188CL", thickness: 188 μm) as a processed sheet, one surface of which was subjected to release treatment using a silicone-based release agent, to form a coating film with a thickness of 200 μm. The laminate formed of the coating film and the processed sheet thus obtained was placed on a conveyor belt. At this time, the coating film surface of the laminate was placed on the upper side, and the longitudinal direction of the laminate was made parallel to the conveying direction of the conveyor belt.

[0239] Furthermore, an ultraviolet spot parallel light source (manufactured by JATEC Co., Ltd.) was set with respect to the conveyor belt on which the laminate was placed, and the parallelism of the central light beam was controlled within ±3°. At this time, the light source was set in a manner that could irradiate parallel light in a direction inclined 10° to the conveying direction of the conveyor belt relative to the normal direction of the surface on the coating film side of the laminate.

[0240] Then, the conveyor belt was operated to move the laminate, and the peak illuminance on the coating surface was 1.06 mW / cm 2 , the accumulated light intensity is 28.76mJ / cm 2 Under the conditions of , irradiate with 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 other peaks at 254nm, 303nm, and 313nm) (first stage irradiation).

[0241] Next, a release-treated surface of a 38 μm-thick release film having ultraviolet transparency (manufactured by LINTEC Corporation, product name “SP-PET382030”) was laminated on the exposed surface of the coating layer.

[0242] Furthermore, an ultraviolet spot parallel light source (manufactured by JATEC Co., Ltd.) whose central light parallelism is controlled within ±3° is provided relative to the conveyor belt on which the laminate is placed. At this time, the light source is provided in a manner capable of irradiating parallel light in a direction inclined 0° toward the conveying direction of the conveyor belt relative to the normal direction of the surface on the coating film side of the laminate.

[0243] Then, the conveyor belt was operated to move the laminate, and the peak illuminance on the coating surface was 2.54 mW / cm 2 , the accumulated light intensity is 46.76mJ / cm 2 Under the conditions, 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 other peaks at 254nm, 303nm, and 313nm) is irradiated through the release film (second stage irradiation).

[0244] Thus, a light diffusion control layer D having a thickness of 200 μm was formed. As a result, a laminated body in which the processed sheet, the light diffusion control layer D (thickness: 200 μm), and the release sheet were sequentially laminated was obtained.

[0245] [Production Example 5] (Light Diffusion Control Layer E)

[0246] A laminated body in which a processed sheet, a light diffusion control layer E (thickness: 110 μm) and a release sheet were sequentially laminated was prepared in the same manner as in Preparation Example 1 except that the irradiation angle of the parallel light irradiated from the ultraviolet spot parallel light source was changed to 20°.

[0247] [Production Example 6] (Light Diffusion Control Layer F)

[0248] A composition for a light diffusion control layer to which no ultraviolet absorber is added is used, and the irradiation angle of the parallel light irradiated from the ultraviolet point parallel light source is changed to 15°, and the light diffusion control layer is further formed in a manner so that the thickness is 120 μm. In addition, a laminated body in which a processed sheet, a light diffusion control layer F (thickness: 120 μm), and a release sheet are sequentially stacked is obtained in the same manner as in Preparation Example 1.

[0249] Table 1 shows the details of the light diffusion control layers A to F produced as described above.

[0250] As shown in Table 1, the cross-sections of the formed light diffusion control layers A, B, C, E, and F were observed under a microscope, etc., and it was confirmed that a column structure consisting of a plurality of columnar objects standing in the entire thickness direction was formed inside the light diffusion control layers A, B, C, E, and F. That is, the ratio of the column structure region extending in the thickness direction inside the obtained light diffusion control layers A, B, C, E, and F was 100%. Figure 5The direction C was confirmed, and the results showed that when the ultraviolet irradiation surface was on the upper side, the conveyor belt travel side (MD direction) was consistent with the direction C.

[0251] It was confirmed that the columns inside the light diffusion control layers A, B, C, and E were all as Figure 4 As shown in (a), the column is bent in the middle of the extension direction. And, it is confirmed that the extension direction ( Figure 5 A direction in the middle) and the thickness direction of the light diffusion control layer ( Figure 5 The angle formed by the direction B Figure 5 , the light diffusion control layer A and B are 3.2°, the light diffusion control layer C is 6.4°, and the light diffusion control layer E is 12.7°. In addition, in this specification, for this angle, the angle when the A direction is inclined toward the conveyor belt travel side (MD direction) with the B direction as the reference is marked as positive, and the angle when it is inclined to the opposite side of the conveyor belt travel side is marked as negative.

[0252] The columns inside the light diffusion control layer F, such as Figure 4 As shown in (c), it is confirmed that the column is not bent but extends in a substantially straight line. Figure 5 A direction in the middle) and the thickness direction of the light diffusion control layer F ( Figure 5 The angle formed by the direction B Figure 5 The light diffusion control layer D in the middle has an angle a) of 9.6°, which will be described below.

[0253] In addition, the cross section of the light diffusion control layer D was observed under a microscope, and it was confirmed that a column structure consisting of a plurality of columns standing in the entire thickness direction was formed in the state of stacking two layers inside the light diffusion control layer D. When the two layers were considered together, the proportion of the column structure area inside the light diffusion control layer D extending in the thickness direction was 100%. Figure 4 That is, in the layer on the ultraviolet irradiation side (sometimes referred to as the "first layer"), it is confirmed that the columns are arranged in a manner substantially parallel to the thickness direction of the light diffusion control layer D (that is, substantially perpendicular to the main surface of the light diffusion control layer D). In contrast, in another layer (sometimes referred to as the "second layer"), it is confirmed that the columns are inclined relative to the thickness direction of the light diffusion control layer D and are bent in the extending direction. Figure 5 The results showed that when the ultraviolet irradiation surface was on the upper side, the conveyor belt travel side (MD direction) was consistent with the direction C. In addition, it was confirmed that the extension direction ( Figure 5A direction in the middle) and the thickness direction of the light diffusion control layer D ( Figure 5 The angle formed by the direction B Figure 5 The angle a) is 6.4°.

[0254] [Preparation Example 1] (Composition for forming an intermediate adhesive layer)

[0255] 90 parts by mass of n-butyl acrylate and 10 parts by mass of acrylic acid were copolymerized by solution polymerization to obtain a (meth)acrylate polymer. The weight average molecular weight (Mw) of the (meth)acrylate polymer was measured by the method described below and was 400,000.

[0256] 100 parts by mass (value calculated as solid content; the same shall apply hereinafter) of the obtained (meth)acrylate polymer and 0.025 parts by mass of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane as a crosslinking agent were mixed, stirred thoroughly, and diluted with methyl ethyl ketone to obtain a coating solution of a composition for forming an intermediate adhesive layer.

[0257] [Preparation Example 2] (Composition A for forming a diffusion adhesive layer)

[0258] A (meth)acrylate polymer was prepared by copolymerizing 25 parts by mass of n-butyl acrylate, 25 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of isobornyl acrylate, 10 parts by mass of N-acryloylmorpholine, and 30 parts by mass of 2-hydroxyethyl acrylate by a solution polymerization method. The weight average molecular weight (Mw) of the (meth)acrylate polymer was measured by the method described below and was 500,000.

[0259] 100 parts by mass of the obtained (meth)acrylate polymer, 0.2 parts by mass of an isocyanate crosslinking agent as a crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "TAKENATE D101E"), 15 parts by mass of microparticles formed of an organic silicone resin (a silicon-containing compound having an intermediate structure between inorganic and organic) as light diffusing microparticles (manufactured by Momentive Performance Materials Japan, product name "TOSPEARL 145", average particle size: 4.5 μm), and 0.3 parts by mass of 3-glycidyloxypropyltrimethoxysilane as a silane coupling agent were mixed, stirred thoroughly, and diluted with methyl ethyl ketone to obtain a coating solution of a composition A for forming a diffusion adhesive layer.

[0260] [Preparation Example 3] (Composition B for forming a diffusion adhesive layer)

[0261] A coating solution of the diffusive adhesive layer-forming composition B was obtained in the same manner as in Preparation Example 2 except that 0.5 parts by mass of titanium dioxide fine particles (manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., product name “R-62N”, average particle size: 260 nm) were used as light diffusing fine particles.

[0262] The above-mentioned weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

[0263] <Measurement conditions>

[0264] ·GPC measuring apparatus: HLC-8020 manufactured by TOSOH CORPORATION

[0265] ·GPC column (passed in the following order): manufactured by TOSOH CORPORATION

[0266] TSK guard column HXL-H

[0267] TSK gel GMHXL (×2)

[0268] TSK gel G2000HXL

[0269] ·Test solvent: tetrahydrofuran

[0270] ·Measurement temperature: 40℃

[0271] [Example 1]

[0272] (1) Formation of intermediate adhesive layer

[0273] Using a knife coater, the coating solution of the intermediate adhesive layer forming composition obtained in Preparation Example 1 was applied to the release-treated surface of a heavy-release release sheet 1 (manufactured by LINTEC Corporation, product name "SP-PET382050", thickness: 38 μm) in which one surface of a polyethylene terephthalate sheet was release-treated using a silicone-based release agent, and then dried by heating at 90° C. for 1 minute in a drying oven to obtain a coating layer with a thickness of 15 μm.

[0274] Next, the peeling-treated surface of a light-peelable release sheet 1 (manufactured by LINTEC Corporation, product name "SP-PET382120", thickness: 38 μm) obtained by peeling one surface of a polyethylene terephthalate sheet with a silicone-based release agent was attached to the surface of the coating layer on the side opposite to the heavy-peelable release sheet. Then, the coating layer was aged for 7 days at 23° C. and 50% Rh, and the coating layer was used as an intermediate adhesive layer.

[0275] As described above, a laminated body in which the heavy-release type release sheet 1 , the intermediate adhesive layer having a thickness of 15 μm, and the light-release type release sheet 1 were sequentially laminated was obtained.

[0276] (2) Formation of diffusion adhesive layer

[0277] Using a knife coater, the coating solution of the composition A for forming the diffusion adhesive layer obtained in Preparation Example 2 was applied to the peeling-treated surface of a light-peelable release sheet 2 (manufactured by LINTEC Corporation, product name "SP-PET381031", thickness: 38 μm) on which one surface of the polyethylene terephthalate sheet was peeled using a silicone-based release agent, and then heated at 90°C for 1 minute to form a coating layer (thickness: 40 μm). Next, the peeling-treated surface of a heavy-peelable release sheet 2 (manufactured by LINTEC Corporation, product name "SP-PET382120", thickness: 38 μm) was attached to the surface of the coating layer on the opposite side of the light-peelable release sheet. Then, the coating layer was aged for 7 days at 23°C and 50% Rh, and the coating layer was used as a diffusion adhesive layer.

[0278] As described above, a laminated body in which the light release type release sheet 2 , the diffusion adhesive layer having a thickness of 40 μm, and the heavy release type release sheet 2 were laminated was obtained.

[0279] The haze value (%) of the 40 μm thick diffusion adhesive layer formed as described above was measured using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES CO., LTD., product name “NDH5000”) in accordance with JIS K7136:2000, JIS K7361-1:1997 and ASTM D 1003 to find it to be 74%.

[0280] (3) Fabrication of light diffusion control components

[0281] The processing sheet is peeled off from the laminated body prepared in Preparation Example 1 to expose the light diffusion control layer A. In addition, the light peelable release sheet 1 is peeled off from the laminated body prepared in the above step (1) to expose the intermediate adhesive layer. And, the exposed surface of the light diffusion control layer A is bonded to the exposed surface of the intermediate adhesive layer. In addition, the surface of the light diffusion control layer A on the opposite side to the intermediate adhesive layer is the surface irradiated with ultraviolet rays when the light diffusion control layer A is formed.

[0282] Furthermore, the heavy-peelable release sheet 1 on the side opposite to the light diffusion control layer A of the intermediate adhesive layer is peeled off, and the surface of the diffusion adhesive layer exposed by peeling off the light-peelable release sheet 2 from the laminated body prepared in the above step (2) is attached to the exposed surface of the intermediate adhesive layer. Thus, a light diffusion control member is obtained in which the release sheet, the light diffusion control layer A, the intermediate adhesive layer, the diffusion adhesive layer, and the heavy-peelable release sheet 2 are sequentially stacked.

[0283] (4) Preparation of reflective display samples

[0284] Next, a reflector (manufactured by JDSU, product name "BV2 reflector", 75 mm long x 65 mm wide) was prepared. Furthermore, the heavy-peelable release sheet 2 was peeled off from the light diffusion control member obtained in the above step (3), and the exposed surface of the diffusion adhesive layer thus exposed was laminated on the reflective surface of the above reflector. Finally, the release sheet laminated on the light diffusion control layer A was peeled off, thereby obtaining a reflective display sample.

[0285] [Examples 2, 4, 6 to 8 and Comparative Examples 3 to 5]

[0286] Except for changing the type of the light diffusion control layer and the thickness of the diffusion adhesive layer as shown in Table 3, a light diffusion control member was produced in the same manner as in Example 1 to obtain a reflective display sample.

[0287] [Example 3]

[0288] A light diffusion control member was manufactured in the same manner as in Example 1, except that the light diffusion control layer and the diffusion adhesive layer were directly laminated without using an intermediate adhesive layer, thereby obtaining a reflective display sample.

[0289] [Example 5]

[0290] In the formation of the diffusion adhesive layer, the coating solution of the diffusion adhesive layer forming composition B obtained in Preparation Example 3 was used, and the thickness of the diffusion adhesive layer was changed to 25 μm. After manufacturing the light diffusion control member in the same manner as in Example 1, a reflective display sample was further obtained. In addition, Table 3 shows the haze value (%) of the diffusion adhesive layer used in this example.

[0291] [Example 9]

[0292] The release sheet is peeled off from the laminate produced in Production Example 1 to expose the light diffusion control layer A. In addition, the light release type release sheet 1 is peeled off from the laminate produced in the same manner as step (1) of Example 1, and the exposed surface of the intermediate adhesive layer is bonded to the exposed surface of the light diffusion control layer A. Next, the heavy release type release sheet 1 on the side opposite to the light diffusion control layer A of the intermediate adhesive layer is peeled off, and the exposed surface of the diffusion adhesive layer exposed by peeling off the light release type release sheet 2 from the laminate produced in the same manner as step (2) of Example 1 is bonded to the exposed surface of the intermediate adhesive layer. Furthermore, the processed sheet of the light diffusion control layer A is peeled off, and the light release type release sheet 1 is peeled off from the laminate produced in the same manner as step (1) of Example 1, and the exposed surface of the intermediate adhesive layer is bonded to the exposed surface of the light diffusion control layer A. Thus, a light diffusion control member is obtained, which is formed by sequentially stacking the heavy peelable release sheet 2, the diffusion adhesive layer, the intermediate adhesive layer, the light diffusion control layer A, the intermediate adhesive layer, and the heavy peelable release sheet 1. Furthermore, the exposed surface of the intermediate adhesive layer exposed by peeling off the heavy peelable release sheet 1 from the obtained light diffusion control member is stacked on the reflective surface of the reflector in the same manner as in Example 1. Finally, the heavy peelable release sheet 2 stacked on the diffusion adhesive layer is peeled off to obtain a reflective display sample.

[0293] [Comparative Example 1]

[0294] A light diffusion control member was manufactured in the same manner as in Example 1 except that a light diffusion control layer and an intermediate adhesive were not used and a diffusion adhesive layer having a thickness of 60 μm was used as a light diffusion control member to obtain a reflective display sample.

[0295] [Comparative Example 2]

[0296] A light diffusion control member was produced in the same manner as in Example 1 except that the diffusion adhesive layer was not used and a laminated body in which the light diffusion control layer and the intermediate adhesive layer were laminated was used as the light diffusion control member, thereby obtaining a reflective display sample.

[0297] In addition, Table 3 shows the haze value (%) of the diffusion adhesive layer used in each of the Examples and Comparative Examples.

[0298] [Test Example 1] (Measurement of brightness and standard deviation)

[0299] (1) Calculation of standard deviation and determination of exclusion angle

[0300] For the reflective display samples manufactured in the embodiments and comparative examples, Figure 6As shown in (b), a point on the surface (irradiation surface) on the light diffusion control member side is assumed to be the irradiation point ( Figure 6 In (b), the point marked as 201), and at the same time, four directions with azimuth angles of 0°, 90°, 180° and 270° are assumed with the irradiation point as the center. At this time, the light diffusion control layer in the light diffusion control member 1 is set Figure 5 The direction C in the figure is consistent with the azimuth angle of 270°.

[0301] Next, the reflective display sample 200 was placed in a conoscopic polarimeter (manufactured by Autronic Melcher), and the irradiation point was irradiated with light from a direction with an azimuth angle of 0° in the reflection mode, and the brightness distribution of the diffusely reflected light was measured. Figure 6 As shown in (c), the irradiation is performed in such a manner that the angle formed by the light 202 and the normal line of the above-mentioned surface of the reflective display sample 200 is 30°.

[0302] And, if Figure 7 As shown in (b), it is assumed that a plane ( Figure 7 The brightness of the reflected light that enters the plane and forms an angle of less than 30° with the normal line of the irradiated surface is read from the brightness distribution, and the standard deviation of the brightness at an azimuth angle of 0° (cd / m 2 The results are shown in Table 2.

[0303] Furthermore, when the light is irradiated from the azimuth angles of 90°, 180°, and 270°, the plane is assumed in the same manner as above, and the standard deviation of the brightness (cd / m 2 ). These results are shown in Table 2.

[0304] The standard deviation of the maximum value among the standard deviations of the brightness at the four azimuth angles obtained as described above was determined, and the azimuth angle having this standard deviation was regarded as the exclusion angle.

[0305] (2) Measurement of brightness in the front direction

[0306] In the same manner as in step (1), the reflective display sample is irradiated with light at four azimuth angles, and the brightness distribution of the diffusely reflected light is measured. And, from the brightness distribution at the four azimuth angles obtained, the reflected light ( Figure 7 In (a), the brightness (cd / m 2). The results are shown in Table 3. However, in Table 3, the brightness at the exclusion angle determined in the above step (1) is indicated by a strikethrough.

[0307] Furthermore, the minimum brightness among the brightness of the three azimuth angles excluding the above exclusion angle is set as L min , set the maximum brightness to L max They are shown in Table 3.

[0308] In addition, the reflective display sample was changed to a standard white plate (manufactured by Labsphere, product name "SRS-99-010"), and the same method as above was used to compare the reflective display sample with the L min The brightness distribution is measured at the same azimuth angle of the azimuth. And, the brightness of the reflected light reflected in the front direction is read from the brightness distribution and is set as L STD The results are shown in Table 3.

[0309] (3) Calculation of L1, L2, and L3

[0310] Using the L determined and measured in the above step (2) min , L max and L STD The value of L1=L min / L STD And the formula L2=L min / L max L1 and L2 were calculated. Table 3 shows their values.

[0311] Furthermore, among the four standard deviations obtained in the step (1), the standard deviations of the three azimuth angles excluding the exclusion angle are respectively referred to as L3. This L3 is shown in Table 3. In Table 3, the standard deviations of the exclusion angles are indicated by strikethrough.

[0312] [Test Example 2] (Evaluation of optical performance)

[0313] Under the sunlight of a sunny day and in an indoor environment with multiple lighting, the reflective display samples manufactured in the embodiments and comparative examples are held by hand and the direction of observation or the angle of the reflective display samples is changed, or when they are rotated, in a state equivalent to a white display, according to the following standards, whether there are visual problems caused by a sharp change in brightness or a brightness difference in the plane. The results are shown in Table 4. In addition, the brightness of each environment was measured using an illuminometer (manufactured by HIOKI, product name "3423 LUX HiTESTER"), which was 105000lx under sunlight and 780lx under multiple lighting indoors.

[0314] ○: Even if the viewing angle is changed or rotated, the brightness changes little

[0315] ×: Brightness changes greatly when the viewing angle is changed or rotated

[0316] [Test Example 3] (Evaluation of backscattering properties)

[0317] The heavy-peelable release sheet 2 was peeled off from the light diffusion control member produced in the examples and comparative examples, and the exposed surface of the diffusion adhesive layer was attached to one surface of a black plate (thickness 2 mm) made of polymethyl methacrylate. Next, the release sheet laminated on the light diffusion control layer A was peeled off to obtain a measurement sample.

[0318] In addition, for the light diffusion control member of Example 9, the exposed surface of the intermediate adhesive layer exposed by peeling off the heavy peelable release sheet 1 was attached to the above-mentioned black plate to prepare a measurement sample. In addition, for the light diffusion control member of Comparative Example 1, the exposed surface of the diffusion adhesive layer exposed by peeling off the light peelable release sheet 2 was attached to the above-mentioned black plate to prepare a measurement sample. Further, for the light diffusion control member of Comparative Example 2, the surface of the intermediate adhesive layer on the side opposite to the light diffusion control layer was attached to the above-mentioned black plate to prepare a measurement sample.

[0319] The measurement sample obtained as described above was visually observed under a fluorescent lamp to confirm the color of the black plate viewed through the light diffusion control member. In addition, the backscattering property was evaluated according to the following criteria. The results are shown in Table 4.

[0320] ○: Black without whitish feel.

[0321] ×: Black with a whitish feel.

[0322] In addition, when there is backscattering, the black color of the black plate will be covered with haze, and the black color will be visually recognized as whitish. In other words, the contrast ratio calculated from the white brightness and the black brightness will decrease due to the increase in black brightness.

[0323] [Test Example 4] (Evaluation of durability)

[0324] In the same manner as described in step (1) of [Example 1] above, a laminated body was prepared in which a heavy-peelable release sheet 1, an intermediate adhesive layer with a thickness of 15 μm (hereinafter referred to as a "fixing adhesive layer" to distinguish it from the intermediate adhesive layer in the reflective display body sample), and a light-peelable release sheet 1 were sequentially stacked. Then, the light-peelable release sheet 1 was peeled off from the laminated body, and the exposed fixing adhesive layer was bonded to one surface of a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name "DIAFOIL T600E", thickness: 38 μm) having an easy-adhesive surface on one surface. Next, the heavy-peelable release sheet 1 was peeled off, and the exposed fixing adhesive layer was bonded to the surface on the light diffusion control layer side of the reflective display body sample manufactured in the example and the comparative example, thereby preparing a sample for durability evaluation. The samples were subjected to a durability test 1 in which the samples were stored in a high temperature environment of 85° C. for 500 hours and a durability test 2 in which the samples were stored in a high temperature and high humidity environment of 60° C. and 90% RH for 500 hours.

[0325] Then, the reflective display samples were taken out from each environment, and the states of the interface between the light diffusion control layer and the intermediate adhesive layer, the interface between the intermediate adhesive layer and the diffusion adhesive layer, and the interface between the diffusion adhesive layer and the reflector were visually observed and confirmed, and the durability was evaluated according to the following criteria. The results are shown in Table 4.

[0326] ○ ... No bubbles, floating or peeling occurred at any interface.

[0327] ×… Bubbles, floating, or peeling occurred at a certain interface.

[0328] [Table 1]

[0329]

[0330] [Table 2]

[0331]

[0332] [Table 3]

[0333]

[0334] [Table 4]

[0335]

[0336] As shown in Table 4, by using the light diffusion control components of the embodiments, a reflective display with excellent visual recognition can be manufactured. In particular, the result is that the light diffusion control components of embodiments 1 to 9 have excellent visual recognition in any environment, whether outdoor or indoor. On the other hand, the light diffusion control components of comparative examples 1 to 5 have poor visual recognition. In particular, the light diffusion control components of the comparative examples have significant changes in light and dark when the reflective display sample is rotated or the angle is slightly tilted, and cannot withstand use as a reflective display. In addition, it can be seen that the light diffusion control components of embodiments 1 to 4 and 6 to 9 can well suppress backscattering. Further, it can be seen that the light diffusion control components of embodiments 1 to 2 and 4 to 9 have excellent durability.

[0337] Industrial Applicability

[0338] The light diffusion control member of the present invention is suitable for manufacturing a display body such as a smart phone or a tablet computer configured so that the vertical direction of displayed content can be changed.

[0339] Description of Reference Numerals

[0340] 1a, 1b: light diffusion control component; 11: light diffusion control layer; 12: diffusion adhesive layer; 13: intermediate adhesive layer; 111: area with relatively high refractive index (column); 112: area with relatively low refractive index; 2: display device; 3: reflection layer; 4: reflector; 100: reflective display body; 200: measurement sample; 201: irradiation point; 202: light; 203, 204a, 204b: reflected light.

Claims

1. A light diffusion control member, characterized in that: The light diffusion control layer has a regular internal structure including a plurality of relatively high refractive index regions in a relatively low refractive index region, and the diffusion adhesive layer is laminated on one surface side of the light diffusion control layer and contains light diffusing fine particles. Among them, for any point on the surface of one side of the light diffusion control member of the measurement sample formed by laminating any one surface of the light diffusion control member on the reflecting surface of any reflector, light rays with an angle of 30° with the normal of the surface are irradiated from four directions with azimuths of 0°, 90°, 180° and 270° centered on the point, respectively, so that each of the azimuths generates reflected light diffusely reflected from the point, and for the reflected light that enters a plane that includes the point and the normal and is perpendicular to the azimuth of the irradiated light and at the same time forms an angle of less than 30° with the normal, the standard deviation (cd / m2) of the brightness of these reflected lights is calculated for each of the azimuths, and the azimuth that gives the maximum standard deviation is used as the exclusion angle, For any point on the surface of the light diffusion control member on one side of the measurement sample, light rays with an angle of 30° with respect to the normal line of the surface are irradiated from the azimuths of three directions excluding the exclusion angle from the azimuths of the four directions, so that each of the azimuths of the three directions generates reflected light diffusely reflected from the point, and for each of the azimuths of the three directions, the brightness (cd / m 2 ), the minimum brightness value among the three brightnesses obtained is set as L min , set the maximum brightness value to L max , For any point on a surface of any standard white plate, the L min The azimuth angle of the light irradiated by the normal line of the one surface is 30°, and the brightness (cd / m 2 ) is set to L STD hour, L1=L min / L STD The L1 represented by satisfies the following formula (1), L1＞1.00…(1)， L2=L min / L max The L2 represented by satisfies the following formula (2), 0.70≤L2≤1.00…(2)， When the standard deviations (cd / m2) of the azimuth angles in three directions excluding the exclusion angle among the azimuth angles in the four directions are respectively set as L3, all L3 in the three directions satisfy the following formula (3): L3＜2.00…(3)。 2. The light diffusion control member according to claim 1, wherein: The relatively high refractive index region is a columnar structure extending from one surface side to the other surface side of the light diffusion control layer. The light diffusion control layer includes at least one layer having a columnar structure in which the columns stand in the region with a relatively low refractive index. In at least a portion of the columnar object, a straight line parallel to the extending direction is inclined with respect to a thickness direction of the light diffusion controlling member.

3. The light diffusion control member according to claim 2, wherein: In at least one of the layers composed of the pillar structures, the pillars are bent between one end and the other end thereof.

4. The light diffusion control member according to claim 2, wherein: The light diffusion control layer includes two layers composed of the column structure.

5. The light diffusion control member according to claim 1, wherein: The light diffusion control layer includes an intermediate adhesive layer stacked between the light diffusion control layer and the diffusion adhesive layer. The intermediate adhesive layer is composed of an adhesive containing a carboxyl group.

6. The light diffusion control member according to claim 1, wherein: The light diffusing fine particles are fine particles composed of a silicon-containing compound having an intermediate structure between inorganic and organic.

7. A reflective display, characterized in that: It is a reflective display body configured so that the vertical direction of the display content on the display surface can be changed, and it has: The light diffusion control member according to claim 1; A display device provided on any one side of the light diffusion control member; and A reflective layer provided on a surface of the display device opposite to the light diffusion control member or incorporated in the display device.

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