JP2015114585A - Anisotropic light diffusion sheet and light diffusion method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide light diffusion means suitable for illumination and display devices that evenly irradiate rectangular or elliptical areas with light.SOLUTION: An anisotropic light diffusion sheet has a first concavo-convex pattern comprising a repetition of wavy protrusions and recesses formed on one surface of the sheet along one direction Y, and a second concavo-convex pattern comprising a repetition of wavy protrusions and recesses formed on a surface of the first concavo-convex pattern along the direction Y, where the first and second concavo-convex patterns look meandering when viewed from the front surface thereof. When light enters the anisotropic light diffusion sheet from the surface having the first and second concavo-convex patterns and exits from a surface opposite the surface with a dual concavo-convex pattern, a 1/10 value angle exceeds 80° in the direction Y and is 5-15° in a direction X perpendicular to the direction Y.

Description

  The present invention relates to an anisotropic light diffusing sheet and a light diffusing method using the anisotropic light diffusing sheet.

  As an illumination device that diffuses and irradiates light in all directions instead of irradiating light in all directions, the illumination devices described in Patent Documents 1 and 2 have been proposed.

The illumination device of Patent Document 1 condenses light from a plurality of point light sources arranged in a straight line in a direction perpendicular to the arrangement direction of the point light sources by a condensing lens, and further collects the condensed light by a light diffusion unit. It is a lighting device that diffuses randomly.
The illumination device of Patent Document 2 condenses light from a plurality of point light sources arranged in a straight line in a direction orthogonal to the arrangement direction of the point light sources by a condensing lens, and further performs desired irradiation of the condensed light. It is an illuminating device which shields the light irradiated out of the range by the shielding means.

JP-A-2005-156600 JP2011-133347A

  The illumination device of Patent Document 1 controls the irradiation range by focusing light in a direction orthogonal to the arrangement direction with a lens. Such a control method has no problem when it is irradiated in a thin line like a scanner light source. However, when applied to a lighting device or a display device that irradiates a rectangular or elliptical range, the light concentrates in the central portion in the longitudinal direction, resulting in a difference in brightness between the central portion and the end portion.

Further, even when a shielding unit is used as in the illumination device of Patent Document 2, the problem of light concentration at the central portion in the longitudinal direction cannot be solved.
Further, when the light shielding means is made of a light absorbing material, there is a problem that the light utilization efficiency is lowered, and even when the light shielding means is made of a light reflecting material, there is a problem that unevenness occurs in brightness.
An object of the present invention is to obtain a light diffusing unit suitable for a lighting device or a display device that irradiates a rectangular or elliptical range without any spots.

The present invention includes the following aspects.
[1] It has a first uneven pattern formed by repeating wavy unevenness along one direction Y on one side of the sheet, and has a wavy uneven surface along the direction Y on the surface of the first uneven pattern. Is an anisotropic diffusion sheet having a second concavo-convex pattern formed by being repeated, wherein the first and second concavo-convex patterns meander when viewed from the surface, The 1/10 value angle when light is incident from the surface having the first and second uneven patterns of the anisotropic diffusion sheet and is emitted from the surface opposite to the surface having the first and second uneven patterns is An anisotropic light diffusing sheet characterized by being over 80 ° in the direction Y and 5 to 15 ° in the X direction orthogonal to the direction Y.
[2] The anisotropic light diffusion sheet according to [1], wherein the first concavo-convex pattern has an orientation degree of 0.2 to 0.5, and the second concavo-convex pattern has an orientation degree of 0.2 to 0.5. .
[3] The anisotropic light diffusion sheet according to any one of [1] and [2], wherein a difference between an orientation direction of the first uneven pattern and an orientation direction of the second uneven pattern is within 5 °.
[4] The difference according to any one of [1] to [3], wherein the most frequent pitch of the first uneven pattern is 3 to 20 μm, and the most frequent pitch of the second uneven pattern is 0.3 to 2.0 μm. Isotropic light diffusion sheet.
[5] Surface in which substantially parallel light is incident on the surface on which the first concavo-convex pattern is formed of the anisotropic light diffusing sheet according to any one of [1] to [4], and the first concavo-convex pattern is not formed. Light diffusing method of emitting from
[6] The light diffusion method according to [5], wherein an angle formed by a surface of the anisotropic light diffusion sheet and an optical axis of the substantially parallel light is in a range of 60 to 90 degrees.

  With the anisotropic diffusion sheet of the present invention, it is possible to obtain an illuminating device that has high utilization efficiency of light energy and can irradiate light uniformly in a rectangular or elliptical shape.

It is an expansion perspective view which shows one Embodiment of the anisotropic light-diffusion sheet of this invention. It is sectional drawing at the time of cut | disconnecting the anisotropic light-diffusion sheet | seat of FIG. 1 along the direction (Y direction) in which the unevenness | corrugation of a 1st uneven | corrugated pattern repeats. It is an example of the electron micrograph which image | photographed the 1st uneven | corrugated pattern and 2nd uneven | corrugated pattern of the anisotropic light-diffusion sheet of this invention from the normal line direction. It is an example of the electron micrograph which image | photographed the 1st uneven | corrugated pattern of the anisotropic light-diffusion sheet of this invention from the normal line direction. It is an image after carrying out the Fourier transform of the gray scale image of the electron micrograph of FIG. FIG. 4 is an image after Fourier transform of the gray scale image of the electron micrograph of FIG. 3. 6 is a graph created with the frequency of the distance (pitch) between the ridges 11a obtained from the Fourier transform image of FIG. 5 as the vertical axis and the distance from the center as the horizontal axis. In the Fourier transformed image of FIG. 5, so that the maximum frequency D ₁ of the pitch of the protrusions 11a passes through the X-axis, a Fourier transform image obtained by rotating the center portion of the Fourier transformed image as an axis. On the vertical axis the frequency of the cycle on the auxiliary line M ₁ derived from the Fourier variable image of FIG. 8 is a graph that created the distance from the maximum frequency D ₁ abscissa. In the Fourier transform image of FIG. 5, an angle θ ₁ formed by a position D ₁ that indicates the maximum frequency of the pitch of the protrusion 11 a other than the center portion of the Fourier transform image and a line L ₁ drawn at the center portion of the Fourier transform image. It is drawing which described. It is a figure used for description of the illumination intensity curve for evaluating light diffusivity. It is a figure which shows the breadth of the emitted light at the time of irradiating substantially parallel light to the anisotropic light diffusion sheet of this invention. It is a figure which shows the evaluation method of the Example of an anisotropic light-diffusion sheet of this invention, and a comparative example.

  In the following description, the shape and arrangement of the anisotropic light diffusion sheet of the present invention will be described with reference to the XYZ orthogonal coordinate system shown in FIG. In this specification, in this XYZ orthogonal coordinate system, the Y direction and the X direction are assumed to be parallel to the XY plane, and the normal line of the anisotropic light diffusion sheet is defined as the Z-axis direction.

(Anisotropic light diffusion sheet)
An embodiment of the anisotropic light diffusion sheet of the present invention will be described.
1 and 2 show an anisotropic light diffusion sheet of this embodiment. The anisotropic light diffusion sheet 1 of the present embodiment has an uneven pattern 10 on at least one surface thereof. Here, the concavo-convex pattern 10 includes a first concavo-convex pattern 11 and a second concavo-convex pattern 12 formed on the surface of the first concavo-convex pattern 11.

  The first concavo-convex pattern 11 is formed by arranging a plurality of protrusions along the Y direction on the surface of the anisotropic light diffusion sheet 1. Hereinafter, one of the protrusions of the first concavo-convex pattern 11 will be described as “protrusion 11a”, and the valley bottom portion of the recess between any adjacent protrusions 11a will be described as “recess 11b”.

Here, the “protrusion” means an elongated protrusion extending on the sheet surface.
In addition, “adjacent ridges” refers to an arbitrary ridge 11a and a ridge 11a arranged immediately beside it in the Y direction.
The second concavo-convex pattern 12 is formed by arranging a plurality of protrusions on the surface of the first concavo-convex pattern 11 in the Y direction. Hereinafter, one of the protrusions of the second concavo-convex pattern 12 will be described as a “protrusion 12a”, and a valley bottom portion of a recess between any adjacent protrusions 12a will be described as a “recess 12b”.

  In the present embodiment, when the surface having the concavo-convex pattern 10 of the anisotropic light diffusing sheet 1 is observed from the normal direction, it is preferable that the ridge line of the protruding portion 11a meanders. That is, each ridge line of the ridge portion 11a has a traveling axis extending in the X direction, but it is preferable that the ridge line meanders from side to side about the traveling axis. Similarly, when the surface having the concavo-convex pattern 10 of the anisotropic light diffusing sheet 1 is observed from the normal direction, it is preferable that the ridge line of the protruding portion 12a meanders.

Here, the “ridge line of the protrusion 11a” means a line that connects the tops of the protrusion 11a. Further, the “ridge line of the ridge portion 12a” means a line that connects the top portions of the ridge portion 12a and continues.
Moreover, the ridgeline of the protrusion part 11a points out the line which looks white in the electron micrograph of FIG. In addition, the ridge line of the ridge portion 12a indicates a line that appears white on the surface of the ridge portion 11a of the first uneven pattern 11 in the electron micrograph of FIG.

  In one aspect of the present invention, each protrusion forming the first concavo-convex pattern 11 may have a height difference in the X direction. Moreover, each protrusion which forms the 2nd uneven | corrugated pattern 12 may have a height difference in the X direction. Here, “having a height difference in the X direction” means that the height of the ridge portion 11a and the ridge portion 12a in the cross-sectional view (FIG. 2) obtained by cutting the anisotropic light diffusion sheet 1 along the Y direction. It means that the height of is changing in the X direction. The height of the protrusion 11a and the height of the protrusion 12a will be described later.

  In one aspect of the present invention, when the anisotropic light diffusion sheet 1 is cut along the Y direction, the cross-sectional view thereof has a shape as shown in FIG. In other words, the cross-sectional shape of the ridge portion 11a changes irregularly in the Y direction, and a plurality of wavy cross sections of the ridge portion 12a are formed along the outline of the cross-sectional shape of the ridge portion 11a. It is preferable.

  As shown in FIG. 2, the cross-sectional shape of the some protrusion 11a which forms the 1st uneven | corrugated pattern 11 is different, respectively, and is not the same. Similarly, the cross-sectional shapes of the protrusions 12a forming the second uneven pattern 12 are also different from each other and are not the same. In one aspect of the present invention, when the anisotropic light diffusing sheet 1 is cut along the Y direction, the cross-sectional shape of the protrusion 11a that forms the first concavo-convex pattern 11 and the second concavo-convex pattern 12 are formed. The cross-sectional shape of the protruding ridge portion 12a is preferably a pleated shape, a shape having a part of a spindle shape, or a dome shape extended in one direction.

In addition, when the anisotropic light diffusion sheet 1 is cut along the Y direction, it is preferable that at least one of the size and shape of the cross section of the protrusion 11a is changed along the X direction. Similarly, when the anisotropic light diffusing sheet 1 is cut along the Y direction, it is preferable that at least one of the size and shape of the cross section of the protrusion 12a is changed along the X direction. Such a shape produces irregularities in the ridges of the ridges constituting the first concavo-convex pattern 11 and the second concavo-convex pattern 12, and an anisotropic light diffusing sheet that is uniform and does not generate a fringe pattern is obtained.
Here, the “fringe pattern” means a striped pattern generated when light passes through a light diffusion sheet having a regular uneven pattern.

The intervals between the ridge lines of the plurality of ridge portions 11a change irregularly in the Y direction. Moreover, it is preferable that the space | interval of the ridgeline of the two adjacent protrusion parts 11a is changing irregularly and continuously in the X direction. However, in the Y direction and the X direction, a portion where the interval between the ridge lines of the ridge portion 11a does not change may be included. Moreover, the ridgeline of the protrusion part 11a may be branched into the ridgeline of arbitrary other protrusion part 11a in the middle, and the ridgeline of the some protrusion part 11a may overlap. Such branching or unity of the ridges of the ridges 11a is a factor that produces irregularities in the intervals between the ridges of the ridges 11a.
Here, “the interval between the ridge lines of two adjacent ridges 11a” means the interval (distance) between the top and the top of the two ridges 11a adjacent in the Y direction.

FIG. 3 is an example of an electron micrograph of the anisotropic light diffusing sheet 1 taken from the normal direction of the first concavo-convex pattern 11 and the second concavo-convex pattern 12.
As shown in FIG. 3, the second concavo-convex pattern 12 is formed by arranging a plurality of protrusions 12 a on the surface of the first concavo-convex pattern 11.
The intervals between the ridge lines of the plurality of ridge portions 12a change irregularly in the Y direction. Moreover, it is preferable that the space | interval of the ridgeline of the two adjacent protrusion parts 12a is changing irregularly and continuously in the X direction. However, in the Y direction and the X direction, a portion where the interval between the ridge lines of the ridge 12a does not change may be included. Moreover, the ridgeline of the ridge part 12a may be branched into the ridgeline of any other ridge part 12a in the middle, and the ridgeline of the some protrusion part 12a may overlap.

As described above, the interval between the ridge lines of the ridges 11a of the first concavo-convex pattern 11 and the interval between the ridge lines of the ridges 12a of the second concavo-convex pattern 12 are not constant. In one embodiment of the anisotropic light-diffusing sheet of the present invention, "pitch" representing the distance between the ridges of the two ridges 11a adjacent to each other, it can be expressed as the pitch P ₁ most frequent. Here, the “most frequent pitch P ₁ ” means a distance between ridge lines having the highest appearance frequency among ridge line intervals (distance between ridge lines) of two adjacent ridges 11a.

In one aspect of the present invention, the most frequent pitch P ₁ of the first uneven pattern 11 is preferably 3 to 20 μm, more preferably 5 to 15 μm, and still more preferably 8 to 13 μm. . Even if the most frequent pitch P ₁ is less than the lower limit, that is, less than 3 μm, or exceeds the upper limit, that is, exceeds 20 μm, the light diffusibility is impaired.

The most frequent pitch P ₁ is a value obtained from the following equation (1).
Most frequent pitch P ₁ = 1 / E ₁ (1)
Specifically, the modal pitch P ₁ can be obtained from an electron microscopic image of the anisotropic light-diffusing sheet. Below, the calculation method of the most frequent pitch using an electron microscope is demonstrated.
First, the surface on which the uneven pattern 10 of the anisotropic light diffusion sheet 1 is formed is observed with an electron microscope from the normal direction. The observation conditions are preferably an acceleration voltage of 15 to 20 kV and a working distance of about 5 to 15 mm. The observation magnification in the electron microscope observation is preferably adjusted as appropriate so that the number of arrangement of the protrusions 11a of the first concavo-convex pattern 11 is 20 to 50 rows.

  Next, the obtained electron micrograph (FIG. 4) is two-dimensionally Fourier transformed to obtain a Fourier transformed image (FIG. 5). Here, when the obtained electron micrograph is a compressed image such as JPEG, it is preferable to perform a two-dimensional Fourier transform after converting to a gray scale image such as a TIFF image. In the Fourier transform image of FIG. 5, the orientation from the center means the periodic structure existing in FIG. 4, that is, the direction in which the protrusions 11 a forming the first concavo-convex pattern 11 are arranged. The distance means the reciprocal of the period of the periodic structure existing in FIG.

Further, the shading of the image in FIG. 5 represents the frequency of the periodic structure, and the lighter the light, the higher the frequency of the target periodic structure in the periodic structure included in FIG.
Subsequently, the electron microscope observation of the second concavo-convex pattern 12 is performed with the observation conditions unchanged. The observation magnification is appropriately changed so that the number of arrangement of the protrusions 12a in the Y direction is 20 to 50 rows. The obtained electron micrograph (see FIG. 3) is two-dimensionally Fourier transformed to obtain a Fourier transformed image (FIG. 6). Here, when the obtained electron micrograph is a compressed image such as JPEG, it is preferable to perform a two-dimensional Fourier transform after converting to a gray scale image such as a TIFF image.

Then, other than the center of the Fourier transform image of FIG. 5, a straight line is drawn L ₁ so as to pass through the position D ₁ indicating the maximum frequency of the pitch of the protrusions 11a, the pitch of the protrusions 11a on the straight line L ₁ A graph is created with the vertical axis as the frequency and the distance from the center (reciprocal of the period) as the horizontal axis (FIG. 7). In the graph of FIG. 7, the most frequent pitch P ₁ can be obtained from the reciprocal of the distance E ₁ at which the frequency is maximum.

The first uneven patterns 11 is preferably protrusions 11a aspect ratio _{A 1} of 0.1 to 1.0, more preferably 0.2 to 0.8, 0.3 More preferably, it is -0.6. Aspect ratio A ₁ is less than the lower limit value and light diffusibility is not sufficient, there is a possibility that unevenness when A ₁ exceeds the upper limit value is destroyed by abrasion and the like.

Here, the aspect ratio _{A 1} of the protrusions 11a is a value determined by the average height _{B 1} / modal pitch _{P 1} of the ridge portion 11a.
Average height B ₁ of the ridge portion 11a is determined as follows. That is, the surface of the anisotropic light diffusing sheet 1 on which the concave / convex pattern 10 is formed is observed with an electron microscope from the normal direction, and a cross-sectional view (see FIG. 2) cut along the Y direction is obtained from the observed image. Here, the observation conditions of the electron microscope may be the same as the conditions used in determining the most frequent pitch P ₁ of the foregoing.

As shown in FIG. 2, the height of the protrusion 11a forming the first uneven pattern 11 is 1 of the sum of the distances in the third direction from the two adjacent recesses 11b to the top of the protrusion 11a. / 2. That is, the height _{b i} protrusions 11a for forming the first uneven patterns 11, the height of the ridges 11a measured from the recess 11b on one side of the ridge portion 11a _{L i,} the other side When the height measured from the bottom of the concave portion 11b is R _i , b _i = (L _i + R _i ) / 2. In this way determine the height b _i of each ridge 11a. Then, by measuring the height R _i and L _i of 50 protrusions 11a calculates the height b _i, and averaging the height by determining the average height B _1.

In the first concavo-convex pattern 11 in the present embodiment, the anisotropic light diffusing sheet 1 is observed from the normal direction, and the ridge line of the protruding portion 11a meanders. In this specification, the degree of meandering of the ridge protrusions 11a of the first uneven patterns 11 that the degree of orientation C _1. As the value of the orientation degree C ₁ is large, the ridge line of the ridge portion 11a means that meanders. Here, the “degree of orientation C ₁ ” is the degree of meandering with respect to the X direction of the ridge line of the ridge 11 a. In other words, the "value of orientation degree C ₁ is large" ridge of the ridge portion 11a, means in the state in which meanders in a large swing width to the left and right about the traveling axis of the above.

The degree of orientation C ₁ of the first concavo-convex pattern 11 is preferably 0.2 or more, more preferably 0.25 or more, and further preferably 0.30 or more. Less than the degree of orientation C ₁ is the lower limit, i.e., is less than 0.2, there is the light diffusing properties are impaired.
On the other hand, the degree of orientation C ₁ of the first concavo-convex pattern 11 is preferably 0.50 or less, more preferably 0.45 or less, and further preferably 0.40 or less. Orientation degree C ₁ is less than the upper limit, i.e., if 0.50 or less, the anisotropic light-diffusing property of light is diffused strongly in the Y direction than in the X direction is obtained. That is, the degree of orientation C ₁ of the first uneven pattern 11 is preferably 0.20 to 0.50, and more preferably 0.30 to 0.40.

Orientation degree C ₁ is determined by the following method.
First, using the Fourier transform image of FIG. 5 obtained when obtaining the most frequent pitch P ₁ , the center portion of the Fourier transform image is such that the maximum pitch frequency D ₁ of the protrusion 11 a passes on the X axis. A Fourier transform image rotated about the axis is created (FIG. 8). Here, the “X axis” refers to a line that passes through the center of the Fourier transform image and is horizontal to the image. Then, through the maximum frequency D _1, drawn parallel auxiliary lines M ₁ in the Y direction, the frequency of the cycle of the auxiliary lines M ₁ on the vertical axis, to create a graph the distance from the maximum frequency D ₁ abscissa (FIG. 9). From the graph of FIG. 9, the half value V ₁ of the obtained peak (the width of the peak at a position where the frequency value of the period on the auxiliary line M ₁ becomes half of the maximum frequency D ₁ ) is obtained. The obtained value by applying the following equation (2) determines the degree of orientation C _1.
Degree of orientation C ₁ = V ₁ / E ₁ (2)

In the first concavo-convex pattern 11 in the present embodiment, the top of the ridge portion 11a and the concave portion 11b are rounded, and the wavy concavo-convex shape including the ridge portion 11a and the concave portion 11b is sinusoidal. Here, “sinusoidal” is a cross-sectional view of the first concavo-convex pattern 11 cut along the Y direction, and the inclination of the tangent of the cross-sectional shape of the protrusion 11a of the first concavo-convex pattern 11 and the concave portion 11b. It means that the inclination of the tangent of the cross-sectional shape of the above changes continuously.
It is preferable that the wavy unevenness including the protrusions 11a and the recesses 11b of the first uneven pattern 11 is sinusoidal because a sheet having excellent light diffusibility can be obtained.

In the present embodiment, the most frequent pitch P2 of the _second uneven pattern 12 is preferably 0.3 to 2.0 μm, more preferably 0.4 to 1.0 μm, and More preferably, it is 5-0.8 micrometers. Also be a most frequent pitch P ₂ is less than the lower limit value exceeds the upper limit, light diffusion is impaired.

Modal pitch P ₂ is a value obtained from the following equation (3).
Most frequent pitch P ₂ = 1 / E ₂ (3)
Specifically, the modal pitch P ₂ can be determined from an electron microscope image of the anisotropic light-diffusing sheet. Modal pitch P _2, using the Fourier transform image of FIG. 6, by the same method as the method of calculating the most frequent pitch P ₁ of the first uneven patterns 11, can be obtained.

That is, a straight line is drawn so as to pass through the position indicating the maximum frequency of the pitch of the ridges 12a other than the center of the Fourier transform image of FIG. 6, and the pitch frequency of the linear ridges 12a is plotted on the vertical axis. Create a graph with the horizontal axis representing the distance from the center (the reciprocal of the period). In this graph, the most frequent pitch P ₂ can be obtained from the reciprocal of the distance E _{2 with} the maximum frequency.

Moreover, as for the 2nd uneven | corrugated pattern 12, it is preferable that aspect ratio A2 of the protrusion 12a is 0.10-0.50, It is more preferable that it is 0.20-0.40, 0.25- More preferably, it is 0.35. The aspect ratio A ₂ by the above-described range, good light diffusion property is obtained.

Here, the aspect ratio _{A 2} protrusions 12a is a value determined by the average height _{B 2} / modal pitch _{P 2} of the protrusions 12a.
Average height B ₂ of the protrusions 12a is determined as follows. That is, the surface of the anisotropic light diffusing sheet 1 on which the concave / convex pattern 10 is formed is observed with an electron microscope from the normal direction, and a cross-sectional view (see FIG. 2) cut along the Y direction is obtained from the observed image. Here, the observation conditions of the electron microscope may be the same as the conditions used in determining the most frequent pitch P ₁ of the foregoing.

As shown in FIG. 2, the height of the protrusion 12a forming the second uneven pattern 12 is ½ of the sum of the distances from the two adjacent recesses 12b to the top of the protrusion 12a. . Here, the distance from the recess 12b to the top of the ridge 12a is parallel to the line connecting the top of the ridge 11a and the recess 11b, and the imaginary line passing through the top of the ridge 12a. The distance in the vertical direction. That is, the height of the protrusions 12a to form the second uneven patterns 12, the recess the height of the ridges 12a measured from the recess 12b on one side of the projecting portions 12a L _S, the other side When the height measured from 12b is R _S , b _S = (L _S + R _S ) / 2. In this way, the height b _S of each protrusion 12a is obtained. Then, by measuring the height R _S of 50 protrusions 12a, and the average thereof height obtaining the average height B _2.

The second concavo-convex pattern 12 in the present embodiment also has the ridge line of the ridge portion 12a meandering when the anisotropic light diffusion sheet 1 is observed from the normal direction. In the present specification, the degree of meandering of the ridge line of the ridge portion 12a in the X direction is referred to as “orientation degree C ₂ ”. As the value of the orientation degree C ₂ is large, the edge line of the ridge portion 12a means that meanders.

In one aspect of the present invention, the degree of orientation _{C 2} is preferably 0.2 or more, more preferably 0.25 or more, further preferably 0.30 or more. Less than the degree of orientation C ₂ is the lower limit, i.e., is less than 0.2, there is the light diffusing properties are impaired.

In addition, the degree of orientation C2 of the _second uneven pattern 12 is preferably 0.50 or less, more preferably 0.45 or less, and further preferably 0.40 or less. Orientation degree C ₂ is less than the upper limit, i.e., if 0.50 or less, the anisotropic light-diffusing property of light is diffused strongly in the Y direction than in the X direction is obtained. That is, the degree of orientation C2 of the _second uneven pattern 12 is preferably 0.20 to 0.50, and more preferably 0.30 to 0.40.

The degree of orientation C ₂ of the second concavo-convex pattern 12 is the same method as the degree of orientation C _{1 of} the first concavo-convex pattern 11 using the Fourier transform image (FIG. 6) obtained when determining the most frequent pitch P ₂ . Can be obtained.

  The difference between the alignment direction of the first concavo-convex pattern 11 and the alignment direction of the second concavo-convex pattern 12 (hereinafter sometimes simply referred to as “difference in alignment direction”) is that the anisotropy of light diffusion is high. Therefore, it is preferable that it is as small as possible. That is, it is preferable that the difference in the orientation direction is small because the anisotropy of light diffusion is increased and a synergistic effect of anisotropic diffusion of the first uneven pattern 11 and the second uneven pattern 12 is obtained. In the present invention, the difference in orientation direction is preferably within 5 °, more preferably within 2 °. Further, the difference in orientation direction is preferably 1 to 5 °, and more preferably 1 to 2 °.

  Here, the orientation direction of the first concavo-convex pattern 11 means a direction obtained by averaging the directions at the portions of the meandering ridgeline of the first concavo-convex pattern 11. Further, the orientation direction of the second concavo-convex pattern 12 means a direction obtained by averaging the directions of the meandering ridge lines of the second concavo-convex pattern 12.

The orientation direction of the first concavo-convex pattern 11 and the orientation direction of the second concavo-convex pattern 12 can be calculated based on an electron microscope image.
First, an electron microscope image showing 3 obtained when determining the most frequent pitch P ₁ described above, and in FIG. 4, to match the ridge line direction of the ridge common to these images.
In FIG. 5 which is the Fourier transform image of FIG. 4, a line L ₁ drawn from the position D ₁ indicating the maximum frequency of the pitch of the protrusion 11 a to the center of the Fourier transform image, other than the center of the Fourier transform image, The angle θ ₁ formed from the X axis is taken as the orientation direction of the first concavo-convex pattern 11 (see FIG. 10).
Next, in FIG. 6 which is the Fourier transform image of FIG. 3, a line drawn from the position D ₂ indicating the maximum frequency of the pitch of the ridge 12 a to the center of the Fourier transform image other than the center of the Fourier transform image. An angle θ ₂ constituted by L ₂ and the X axis is defined as the orientation direction of the second concavo-convex pattern 12.
The difference in orientation direction can be determined from the difference between the obtained θ ₁ and θ ₂ , that is, the angle represented by θ ₁ −θ ₂ .

  Further, the 1/10 value angle of light when light is incident from the surface having the first uneven pattern 11 and the second uneven pattern 12 of the anisotropic light diffusion sheet 1 of the present invention is the Y direction (main diffusion direction). ) Exceeding 80 °, and preferably 5 ° to 15 ° in the X direction (sub-diffusion direction). Further, the 1/10 value angle is more preferably 81 to 100 ° in the Y direction, and 6 ° to 12 ° in the X direction, 82 to 95 ° in the Y direction, and 6.5 ° to 10 ° in the X direction. More preferably. If the 1/10 value angle of light is within the above range, it is preferable because anisotropic light diffusibility is excellent.

Here, the “1/10 value angle of light” can be obtained by the following method.
First, an illuminance curve is obtained by measuring transmitted scattered light using a goniometer (model: GENESIA Gonio / FFP, manufactured by Genesia). Specifically, the relative illuminance when the illuminance of light emitted perpendicularly from the anisotropic light diffusion sheet (the light emission angle of this light is 0 °) is 1, the light emission angle along the X direction or the Y direction. The relative illuminance from −90 ° to 90 ° is measured at 1 ° intervals to obtain an illuminance curve. Here, the illuminance curve is a curve plotted as shown in FIG. 11 with the horizontal axis as the light emission angle and the vertical axis as the relative illuminance.
Then, a 1/10 value angle of light (W _{2 in} FIG. 11) is obtained from the obtained illuminance curve.

The anisotropic light diffusing sheet 1 may be a sheet itself obtained by a method for producing an anisotropic light diffusing sheet to be described later, or a duplicate sheet obtained by duplicating a sheet obtained by a method for producing an anisotropic light diffusing sheet as an original plate. It may be.
When the anisotropic light diffusing sheet 1 is a sheet itself obtained by the method for manufacturing an anisotropic light diffusing sheet described later, the hard layer that is meandering and the surface follow the deformation of the hard layer when viewed from the cross section. It is composed of two layers of the base material layer deformed. In the case of a duplication sheet, usually, a single layer made of a resin having irregularities transferred to the surface, or an irregularity forming layer having irregularities transferred to one surface and irregularities of the irregularity forming layer are transferred. It is composed of two layers of a flat base material layer laminated on the surface that is not.

The anisotropic light diffusion sheet of the present invention has a first concavo-convex pattern and a second concavo-convex pattern formed on the surface of the first concavo-convex pattern, and the shape of the first concavo-convex pattern and the second concavo-convex pattern, and By adjusting the size as described above, the light use efficiency is high when the light from the light source is incident from the side having the first concavo-convex pattern and the second concavo-convex pattern, and the desired irradiation range is uniform. Can diffuse light.
Moreover, the anisotropic light-diffusion sheet of this invention can also be used as an original plate sheet for manufacturing the anisotropic light-diffusion sheet by transferring the surface shape.

(Method for producing anisotropic light diffusion sheet)
Next, an embodiment of a method for producing the anisotropic light diffusing sheet 1 will be described.
The manufacturing method of the anisotropic light-diffusion sheet 1 of this embodiment has a laminated | multilayer film formation process and a heat contraction process.

[Laminated film forming process]
In the laminated film forming step in the present embodiment, at least one hard layer (hereinafter referred to as “surface smooth hard layer”) having a smooth surface and comprising two kinds of resins is laminated on one surface of the heat-shrinkable resin film. This is a step of obtaining a laminated film. Here, the surface smooth hard layer is a layer having a center line average roughness of 0.1 μm or less as measured by the method described in JIS B0601, and does not soften under a temperature condition for shrinking the heat-shrinkable resin film. Is a layer. Moreover, not softening means that the Young's modulus of the surface smooth layer is 100 MPa or more.

  The heat-shrinkable resin film means a film that shrinks (shrinks) in a specific direction when heated at a temperature of 80 to 180 ° C. As such a film, for example, a polyethylene terephthalate shrink film, a polystyrene shrink film, a polyolefin shrink film, a polyvinyl chloride shrink film, a polyvinylidene chloride shrink film, or the like can be used. Among these, it is preferable to use a polyethylene terephthalate shrink film or a polystyrene shrink film from the viewpoint of heat resistance.

In this embodiment, it is preferable to use a uniaxially stretched film as the heat-shrinkable resin film. Uniaxial stretching may be either longitudinal stretching or lateral stretching.
Further, the heat-shrinkable resin film is preferably stretched at a stretch ratio of 1.1 to 15 times, and more preferably stretched at 1.3 to 10 times.

  Moreover, as a heat-shrinkable resin film, it is preferable that a shrinkage rate is 20 to 90%, More preferably, it is a film with 35 to 75%. In this specification, the shrinkage rate is (shrinkage rate [%]) = {(film length before shrinkage) − (length of film after shrinkage)} / (length of film before shrinkage) × 100 (where “the length of the film” means the length in the shrinking direction of the heat-shrinkable resin film). If the shrinkage rate is not less than the lower limit, that is, not less than 20%, the anisotropic light diffusion sheet 1 can be more easily produced. On the other hand, it is difficult to produce a heat-shrinkable resin film having a shrinkage ratio exceeding the upper limit, that is, exceeding 90%.

  The surface of the heat-shrinkable resin film is preferably flat. If the surface of the heat-shrinkable resin film is flat, it is preferable because the surface smooth hard layer can be easily formed on the surface. Here, “flat” means that the center line average roughness measured by the method described in JIS B0601 is 0.1 μm or less.

The glass transition temperature Tg ₁ of the resin constituting the heat-shrinkable resin film (hereinafter referred to as “resin L”) is preferably 40 to 200 ° C., and more preferably 60 to 150 ° C. The glass transition temperature can be measured by differential thermal analysis or the like. If the glass transition temperature Tg ₁ is 40 to 200 ° C., it can be formed more easily uneven pattern 10. That is, if the glass transition temperature Tg ₁ of the resin L is 40 to 200 ° C., the heat-shrinkable resin film composed of the resin L can be heated and shrunk at a temperature of 80 to 180 ° C. Since the uneven | corrugated pattern 10 can be formed in this, it is preferable.

The Young's modulus of the resin L is preferably 0.01 to 100 MPa and more preferably 0.1 to 10 MPa in the temperature range of the heat shrinking step, that is, in the temperature range of 80 to 180 ° C. If the Young's modulus of the resin L is equal to or higher than the lower limit value, it is a hardness that can be used as a base material, and if it is equal to or lower than the upper limit value, it is soft enough to follow and deform simultaneously when the surface smooth hard layer is deformed. That's it.
The resin having the glass transition temperature Tg ₁ and the Young's modulus as described above is preferably at least one selected from, for example, a polyethylene terephthalate resin, a polystyrene resin, and a polyvinyl chloride resin.

  As the two types of resins constituting the surface smooth hard layer (hereinafter, one is described as “resin M” and the other as “resin N”), for example, polyvinyl alcohol, polystyrene, acrylic resin, and styrene-acrylic resin are used. Polymers, styrene-acrylonitrile copolymers, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethersulfone, fluororesin, and the like can be used.

Further, since the resin M and the resin N can easily form the second concavo-convex pattern 12, it is preferable that the glass transition temperatures are different from each other. Specifically, the glass transition temperature Tg _2M of the resin _M is a glass of the resin N. It is preferable that the transition temperature is higher than Tg _2N . Furthermore, (glass transition temperature Tg _{2M of} resin _M ) − (glass transition temperature Tg _2N of resin N) is preferably 10 ° C. or higher, more preferably 15 ° C. or higher.

On the other hand, since it becomes difficult to form the second uneven pattern 12 even if Tg _2M and Tg _2N are too far apart, Tg _2M -Tg _2N is preferably 20 ° C. or less, and more preferably 19 ° C. or less. . That is, the difference between the glass transition temperature Tg _2M of the resin _M and the glass transition temperature Tg _2N of the resin N is preferably 10 to 20 ° C., and more preferably 11 to 15 ° C.

The difference (Tg _2M −) between the glass transition temperature Tg _2M of the resin _M and the glass transition temperature Tg ₁ of the resin L is that the uneven pattern 10 composed of the first uneven pattern 11 and the second uneven pattern 12 can be easily formed. Tg ₁ ), the difference (Tg _2N −Tg ₁ ) between the glass transition temperature Tg _2N of the resin _N and the glass transition temperature Tg ₁ of the resin L is preferably 10 ° C. or more, more preferably 15 ° C. or more. It is preferably 20 ° C. or higher.

The glass transition temperatures Tg _2M and Tg _2N of the resin M and the resin N are both preferably in the range of 40 to 400 ° C., and more preferably in the range of 80 to 250 ° C. If Tg _2M and Tg _2N are not less than the lower limit and not more than the upper limit, that is, in the range of 40 to 400 ° C., the uneven pattern 10 can be more easily formed.

  The Young's modulus of the resin M and the resin N is preferably in the range of 0.01 to 300 GPa and in the range of 0.1 to 10 GPa in the temperature of the heat shrinking process, that is, in the temperature range of 80 to 180 ° C. It is more preferable. If the Young's modulus of the resin M and the resin N is 0.01 GPa or more, the hardness is sufficient to maintain the shape of the concavo-convex pattern 10, and if the Young's modulus is less than the upper limit value, the concavo-convex pattern is more easily obtained. 10 can be formed.

  In one embodiment of the present invention, the resin M is preferably an acrylic resin, a styrene-acrylic copolymer, or a styrene-acrylic copolymer. Further, the resin N is preferably an acrylic resin, a styrene-acrylic copolymer, or a styrene-acrylic copolymer. The combination of the resin M and the resin N is preferably an acrylic resin and an acrylic resin, an acrylic resin and a styrene-acrylic copolymer, or a combination of an acrylic resin and a styrene-acrylonitrile copolymer, and a combination of an acrylic resin and an acrylic resin. It is more preferable that

The thickness of the surface smooth hard layer is preferably more than 0.05 μm and not more than 5.0 μm, and more preferably 0.5 to 3.0 μm. When the thickness of the smooth surface hard layer on the range, the modal pitch P ₁ is an appropriate range, it is possible to increase the light diffusion property.
The thickness of the surface smooth hard layer may be continuously changed. When the thickness of the surface smooth hard layer is continuously changing, the pitch and height of the protrusions 11a of the first uneven pattern 11 formed after compression, that is, after the heat shrinking step, are continuous. To change.

  As a method of laminating the surface smooth hard layer composed of the above-described resin M and resin N on the surface of the heat-shrinkable resin film, a heat-shrinkable resin film is used as a hard layer-forming coating material containing resin M and resin N. And a method of coating and drying continuously.

  Examples of the method for preparing the hard layer forming paint include a method of diluting with a toluene solvent. Moreover, it is preferable that the solid content density | concentration (resin M and resin N density | concentration) of the said hard layer formation coating material is 1-15 mass% with respect to the total mass of a coating material, and it is 5-10 mass%. Is more preferable.

  Examples of paint coating methods include air knife coating, roll coating, blade coating, Mayer bar coating, gravure coating, spray coating, cast coating, curtain coating, die slot coating, gate roll coating, size press coating, spin coating, Examples include dip coating.

Examples of the drying method include a heat drying method using hot air, infrared rays, or the like.
The dry coating amount of the resin solution on the heat-shrinkable resin film is preferably 1 to 10 g / m ² . If the dry coating amount of the resin solution is 1 to 10 g / m ² , it is preferable because the thickness of the surface smooth hard layer can be within the above-mentioned preferable range, and the uneven pattern 10 is easily formed on the surface smooth hard layer. .

[Heat shrinkage process]
In the heat-shrinking step, the laminated film is heated to shrink the heat-shrinkable resin film, thereby deforming the surface smooth hard layer so as to be folded, thereby forming the uneven pattern 10 on the surface of the heat-shrinkable resin film. It is a process.

  In the heat shrinking step, the laminated film is preferably shrunk at a shrinkage rate of 40% or more. If the shrinkage rate is 40% or more, the portion where shrinkage is insufficient, that is, the portion where the uneven pattern 10 is not formed or the aspect ratio of the protrusions is not sufficiently large even if formed can be reduced. On the other hand, if the shrinkage rate is too large, the area of the anisotropic light diffusing sheet 1 to be obtained becomes small and the yield decreases, so the upper limit of the shrinkage rate is preferably 80%.

  Examples of the method of heating the laminated film include a method of passing it through hot air, steam, hot water, or far-infrared rays. Among them, a method of passing through hot air is preferable because it can be uniformly contracted.

The heating temperature at which the heat-shrinkable resin film is thermally shrunk includes the kind of heat-shrinkable resin film to be used, the most frequent pitch P ₁ of the intended first concavo-convex pattern 11, the aspect ratio A _1, and the degree of orientation C _1. It is preferable to select appropriately according to the most frequent pitch P ₂ and the degree of orientation C ₂ of the target second uneven pattern 12.

Further, the heat shrinkage temperature is preferably set to a temperature equal to or higher than the glass transition temperature Tg ₁ of the resin L constituting the heat shrinkable resin film. When the thermal contraction is performed at a temperature of Tg ₁ or more, the first uneven pattern 11 can be easily formed.

When the glass transition temperature Tg _2M of the resin _M is higher than the glass transition temperature Tg _2N of the resin N, the heat shrinkage temperature is preferably less than (glass transition temperature Tg _2M + 15 ° C. of the resin M).

That is, in one aspect of the present invention, the heat shrinking step is performed by causing the laminated film obtained in the step to pass through hot air at 80 to 180 ° C., more preferably 120 to 170 ° C. It is preferable that it is a process of obtaining the sheet | seat in which the uneven | corrugated pattern 10 was formed in the surface of a surface smooth hard layer by deforming a property film and a surface smooth hard layer. The time for heating the laminated film with hot air is preferably 1 to 3 minutes, and more preferably 1 to 2 minutes. Moreover, as a wind speed of a hot air, it is preferable that it is 1-10 m / s, and it is more preferable that it is 2-5 m / s.

[Adjustment of uneven pattern characteristics]
By adjusting the conditions of the above manufacturing method, the 1/10 value angle in the Y direction and the X direction, the most frequent pitch P ₁ of the first concavo-convex pattern 11, the aspect ratio A ₁ of the protrusion 11a, and the degree of orientation C ₁ , the most frequent pitch P ₂ of the second concavo-convex pattern 12, the aspect ratio A ₂ of the protrusion 12 a, and the orientation degree C ₂ , the orientation direction of the first concavo-convex pattern 11 and the orientation direction of the second concavo-convex pattern 12 The difference between can be adjusted.

  In order to adjust the 1/10 value angle, with respect to the Y direction which is the main diffusion direction, in the heat shrinking step, the shrinkage rate in the Y direction of the laminated film is adjusted to 40% to 60%. The 1/10 value angle can be adjusted to an angle exceeding 80 °. In the X direction, heat shrinkage may be performed while applying an appropriate tension in a direction opposite to the shrinkage direction in the X direction. By adjusting the shrinkage rate in the X direction to 0.5 to 10%, preferably 1 to 5% by the appropriate tension in the X direction, the 1/10 value angle can be adjusted to 5 ° to 15 °. it can.

To adjust the modal pitch P ₁ may be determined as the mixing ratio of the glass transition temperature is high resin M and low resin N. As the blending ratio of the resin M is higher, the most frequent pitch P ₁ tends to increase. That is, if the blending ratio of the resin M and the resin N is 1: 1 to 1: 3, the most frequent pitch P1 of the _first uneven pattern 11 can be adjusted to a range of 3 to 20 μm.

The aspect ratio A ₁ the predetermined protrusions 11a, i.e., to the range of 0.2 to 1.0 may be determined as the mixing ratio of the glass transition temperature is high resin M and low resin N. The higher the mixing ratio of the resin M, the aspect ratio A ₁ is tend to be small. That is, if the compounding ratio of the resin M and the resin N is 1: 1 to 1: 3, the aspect ratio A1 of the protruding portion 11a can be adjusted to a range of 0.2 to 1.0.

The orientation degree _{C 1} the predetermined, i.e., to the range of 0.20 to 0.50 may be adjusted to shrinkage of the heat shrinking process. The degree of orientation C ₁ tends to increase as the shrinkage rate increases. That is, in the heat shrinkage process shrinkage of the laminated film is equal 40% to 60%, it is possible to adjust the degree of orientation _{C 1} in the range of 0.20 to 0.50.

To adjust the modal pitch P ₂ may be determined as the mixing ratio of the glass transition temperature is high resin M and low resin N. The higher the mixing ratio of the resin M, modal pitch P ₂ tends to increase. That is, if the mixing ratio of the resin M and the resin N is 1: 1 to 1: 3, the most frequent pitch P2 of the _second uneven pattern 12 is adjusted to a range of 0.3 to 2.0 μm. Can do.

The aspect ratio _{A 2} protrusions 12a above a predetermined, i.e., to the range of 0.25 to 0.35 may be adjusted to shrinkage of the heat shrinking process. Also, the higher the mixing ratio of the resin M, the aspect ratio A ₂ tends to increase. That is, the mixing ratio of the resin M and resin N is 1: 1 to 1: if 3, the aspect ratio _{A 2} protrusions 12a, can be adjusted in a range of 0.25 to 0.35. Further, in the heat shrinkage step, if the shrinkage ratio 40% to 60% of the laminated film, the aspect ratio _{A 2} protrusions 12a, can be adjusted in a range of 0.25 to 0.35.

Range orientation degree C ₂ of the predetermined, i.e., in order to 0.20 to 0.50, the shrinkage of the heat shrinking step may be adjusted within a certain range. The degree of orientation C ₂ tends to increase as the shrinkage rate increases. That is, in the heat shrinkage process, shrinkage of the laminated film is equal 40% to 60%, it is possible to adjust the degree of orientation _{C 2} in the range of 0.20 to 0.50.

  In order to adjust the difference between the orientation direction of the first concavo-convex pattern 11 and the orientation direction of the second concavo-convex pattern 12, the shrinkage rate of the heat shrinking process is adjusted after adjusting the blending ratio of the resin M and the resin N. do it. The difference in the orientation direction tends to increase as the blending ratio of the resin M increases and the shrinkage rate increases. That is, if the blending ratio of the resin M and the resin N is 1: 1 to 1: 3 and the shrinkage rate of the laminated film in the heat shrinking process is 40 to 60%, the orientation direction of the first uneven pattern 11 And the difference in the orientation direction of the second concavo-convex pattern 12 can be within 5 °.

[Other manufacturing methods]
In the above manufacturing method, the surface smooth hard layer is composed of two kinds of resins, but is not limited thereto.
The anisotropic light diffusing sheet can also be produced by using the one obtained by the above production method as an original sheet and transferring it to another material by the following method.
A resin or metal support for supporting the anisotropic light diffusion sheet 1 may be attached to the original sheet.

Specific methods for producing a new anisotropic light diffusion sheet using the original sheet include, for example, the following methods (a) to (c).
(A) A step of applying an uncured active energy ray-curable resin to the surface of the original sheet on which the concavo-convex pattern is formed, and curing the curable resin by irradiating the active energy ray to cure the curable resin. And a step of peeling the coating film from the original sheet. Here, the active energy ray is usually an ultraviolet ray or an electron beam, but in the present invention, it includes a visible ray, an X-ray, an ion ray and the like.

(B) A step of applying an uncured liquid thermosetting resin to the surface of the original sheet on which the concavo-convex pattern is formed; and heating and curing the liquid thermosetting resin; And a step of peeling from the original sheet.

(C) A step of bringing a sheet-like thermoplastic resin into contact with the surface of the original sheet on which the concave / convex pattern is formed, and the sheet-like thermoplastic resin is heated and softened while being pressed against the original sheet, and then cooled. And a step of peeling the cooled sheet-like thermoplastic resin from the original sheet.

In addition, a molded article for the secondary process can be produced using the original sheet, and a new anisotropic light diffusion sheet can be produced using the molded article for the secondary process. Examples of the molded product for the secondary process include a secondary process sheet. In addition, as the molded product for the secondary process, there is a plating roll obtained by rolling the original sheet and attaching it to the inside of the cylinder, plating with the roll inserted inside the cylinder, and taking out the roll from the cylinder. .
Specific methods using the molded product for the secondary process include the following methods (d) to (f).

(D) A step of performing metal plating such as nickel on the surface of the original sheet on which the concave / convex pattern is formed and laminating a plating layer (material for transferring the concave / convex pattern), and peeling the plating layer from the original sheet, A step of producing a molded product for a secondary process made of metal, and a step of applying an uncured active energy ray-curable resin to the surface on the side in contact with the concave-convex pattern of the molded product for the secondary process; And a step of irradiating active energy rays to cure the curable resin and then peeling the cured coating film from the molded product for the secondary process.

(E) A step of laminating a plating layer (a material for transferring a concavo-convex pattern) on the surface of the original sheet on which the concavo-convex pattern is formed, and a metal molded product for a secondary process by peeling the plating layer from the original sheet. And a step of applying an uncured liquid thermosetting resin to the surface that was in contact with the concave-convex pattern of the molded product for the secondary process, and after curing the resin by heating, And a step of peeling the cured coating film from the molded product for the secondary process.

(F) A step of laminating a plating layer (a material for transferring the concavo-convex pattern) on the surface of the original sheet on which the concavo-convex pattern is formed, and peeling the plating layer from the original sheet to form a metal secondary process molded product. A step of bringing the sheet-like thermoplastic resin into contact with the surface on the side in contact with the concave-convex pattern of the molded article for the secondary process, and molding the sheet-like thermoplastic resin for the secondary process A method comprising a step of heating and softening while pressing against an object and then cooling, and a step of peeling the cooled sheet-like thermoplastic resin from the molded product for the secondary process.

  A specific example of the method (a) will be described. First, an uncured liquid active energy ray-curable resin is applied to the surface of the web-shaped original sheet on which the concavo-convex pattern is formed by a coater. Next, the original sheet coated with the curable resin is pressed by passing it through a roll, and the curable resin is filled into the concave-convex pattern of the original sheet. Then, an active energy ray is irradiated with an active energy ray irradiation apparatus, and curable resin is bridge | crosslinked and hardened. And a web-like anisotropic light-diffusion sheet can be manufactured by peeling the active energy ray-curable resin after hardening from an original sheet.

In the method (a), the surface of the original sheet on which the concavo-convex pattern is formed is formed from a silicone resin, a fluororesin or the like before application of an uncured active energy ray-curable resin for the purpose of imparting releasability. The layer to be formed may be provided with a thickness of about 1 to 10 nm.
Examples of the coater that coats an uncured active energy ray-curable resin on the surface of the original sheet on which the uneven pattern is formed include a T-die coater, a roll coater, and a bar coater.

Uncured active energy ray-curable resins include epoxy acrylate, epoxidized oil acrylate, urethane acrylate, unsaturated polyester, polyester acrylate, polyether acrylate, vinyl / acrylate, polyene / acrylate, silicon acrylate, polybutadiene, and polystyrylmethyl. 1 selected from monomers such as prepolymers such as methacrylate, aliphatic acrylate, alicyclic acrylate, aromatic acrylate, hydroxyl group-containing acrylate, allyl group-containing acrylate, glycidyl group-containing acrylate, carboxy group-containing acrylate, halogen-containing acrylate The thing containing the component more than a kind is mentioned. The uncured active energy ray-curable resin is preferably diluted with a solvent or the like.

Moreover, you may add a fluororesin, a silicone resin, etc. to uncured active energy ray hardening resin.
When the uncured active energy ray-curable resin is cured with ultraviolet rays, it is preferable to add a photopolymerization initiator such as acetophenones and benzophenones to the uncured active energy ray-curable resin.

  After the uncured liquid active energy ray-curable resin is applied, the active energy rays may be irradiated after a substrate made of resin, glass or the like is bonded. Irradiation of active energy rays may be performed from either one of the base material and the original sheet having active energy ray permeability.

  The thickness of the cured active energy ray-curable resin sheet is preferably about 0.1 to 100 μm. If the thickness of the cured active energy ray-curable resin sheet is 0.1 μm or more, sufficient strength can be secured, and if it is 100 μm or more, sufficient flexibility can be secured.

  In the method shown above, the original sheet is web-shaped, but it may be a sheet. Here, “sheet” means a sheet cut into a certain size according to a sheet of printing paper.

  In the case of using a single sheet, a stamp method using a single sheet as a flat plate mold, a roll imprint method using a single sheet wound around a roll as a cylindrical mold, and the like can be applied. Moreover, you may arrange | position the sheet | seat original plate sheet inside the type | mold of an injection molding machine.

  However, in the method using these single sheets, in order to mass-produce the anisotropic light diffusing sheet, it is necessary to repeat the process of forming the uneven pattern many times. When the releasability between the active energy ray-curable resin and the original sheet is low, clogging of the concavo-convex pattern occurs when repeated many times, and the transfer of the concavo-convex pattern tends to be incomplete.

  On the other hand, in the method (a) shown above, since the original sheet is web-like, a concave / convex pattern can be continuously formed in a large area. Therefore, even if the number of times the anisotropic light diffusing sheet is repeatedly used is small, a necessary amount of the anisotropic light diffusing sheet can be produced in a short time.

In the methods (b) and (e), examples of the liquid thermosetting resin include uncured melamine resin, urethane resin, and epoxy resin.
The curing temperature in the method (b) is preferably lower than the glass transition temperature of the original sheet. This is because if the curing temperature is equal to or higher than the glass transition temperature of the original sheet, the concavo-convex pattern of the original sheet may be deformed during curing.

In the methods (c) and (f), examples of the thermoplastic resin include acrylic resin, polyolefin, polyester, and the like.
The pressure when pressing the sheet-like thermoplastic resin against the molded product for the secondary process is preferably 1 to 100 MPa. If the pressure at the time of pressing is 1 MPa or more, the concavo-convex pattern 10 can be transferred with high accuracy, and if it is 100 MPa or less, excessive pressurization can be prevented.

Moreover, it is preferable that the heating temperature of the thermoplastic resin in the method (c) is lower than the glass transition temperature of the original sheet. This is because if the heating temperature is equal to or higher than the glass transition temperature of the original sheet, the uneven pattern 10 of the original sheet may be deformed during heating.
The cooling temperature after heating is preferably less than the glass transition temperature of the thermoplastic resin because the uneven pattern 10 can be transferred with high accuracy.

  Among the methods (a) to (c), the method (a) using an active energy ray-curable resin is preferable in that heating can be omitted and deformation of the uneven pattern of the original sheet can be prevented.

In the methods (d) to (f), it is preferable that the thickness of the metallic secondary process molded product is about 50 to 500 μm. If the thickness of the metal secondary process molded product is 50 μm or more, the secondary process molded product has sufficient strength, and if it is 500 μm or less, sufficient flexibility can be secured.
In the methods (d) to (f), a metal sheet that is small in deformation due to heat is used as an original sheet, so that an active energy ray curable resin, a thermosetting resin, a thermoplastic resin is used as a material for an anisotropic light diffusion sheet. Either of these can be used.

  In addition, in (d)-(f), the uneven | corrugated pattern of the original plate sheet was transcribe | transferred to the metal, and the molding for secondary processes was obtained, However, you may transcribe | transfer to resin and may obtain the molding for secondary processes. Examples of the resin that can be used in this case include polycarbonate, polyacetal, polysulfone, and an active energy ray-curable resin used in the method (a). When the active energy ray-curable resin is used, the active energy ray-curable resin is sequentially applied, cured, and peeled in the same manner as in the method (a) to obtain a molded product for the secondary process.

In addition, using the molded product for the secondary process produced by the above method as the original plate, the molding process for the secondary process similar to the above (d) to (f) is repeated one or more times to mold the secondary process. An anisotropic diffusion sheet can also be manufactured by the method similar to said (d)-(f) by duplicating a thing and using the obtained duplicate as a molding for a secondary process.

(How to use anisotropic light diffusion sheet)
The usage method of the anisotropic light-diffusion sheet of this invention is demonstrated. FIG. 12 is a conceptual diagram showing the spread of light when the condensing lens and the anisotropic light diffusion sheet of the present invention are arranged in illumination in which LED light sources are arranged in a line in a line. FIG. 12-A shows the spread of light when viewed from the position where the LED light source arrangement direction is the left-right direction, and FIG. 12-B is the position where the LED arrangement direction is the front-back direction of the page. It shows the spread of light when viewed.

Light emitted from the LED light source 13 is converted by the condenser lens 14 into substantially parallel light whose irradiation angle is narrowed. The anisotropic light diffusing sheet 1 is disposed on the condenser lens so that the Y direction (substantially the same direction as the first concavo-convex pattern orientation direction) and the arrangement direction of the LED light sources are substantially coincident (see FIG. 12). When the parallel light is incident from the surface having the first and second uneven patterns of the anisotropic light diffusion sheet 1 and is emitted from the surface without the first and second uneven patterns, the light is an anisotropic light diffusion sheet as 15. Compared to the case where there is no 1 (dotted line in FIG. 12), the diffusion is considerably wider in the Y direction and somewhat wider in the X direction (solid line in FIG. 12).

By applying the anisotropic light diffusion characteristics as described above, unnecessary directions (in this case, the X direction) are used for applications such as inspection machines, scanners, and road lighting where it is desired to diffuse light from lines to ellipses. ) To reduce the loss due to the diffusion of the light, and to efficiently irradiate the light (without reducing the illuminance).
Further, in order to suppress Fresnel reflection of light irradiated to the anisotropic light diffusion sheet, the LED is formed so that an angle formed by the irradiation axis of the substantially parallel light and the surface of the anisotropic light diffusion sheet is in a range of 60 ° to 90 °. It is desirable to arrange a light source, a condenser lens and an anisotropic light diffusion sheet.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, the scope of the present invention is not limited to these.

(Example 1)
Acrylic resin (resin N) having a glass transition temperature of 128 ° C. and an acrylic resin (resin M) having a glass transition temperature of 139 ° C. are mixed at a mass ratio of 1: 1, diluted in toluene, and hard layer forming paint (solid content concentration). 8% by mass) was obtained. This coating is dried on a single side of a heat-shrinkable resin film (polyethylene terephthalate-based shrink film, product name SC807, manufactured by Toyobo Co., Ltd., thickness 30 μm) that shrinks mainly in a uniaxial direction. Coating was carried out to 2 μm. Next, by drying, a surface smooth hard layer was formed to obtain a laminated sheet.

  Next, both ends of the laminated sheet were fixed with clamps so that tension was applied in the main shrinking direction of the laminated sheet. Furthermore, both ends of the direction orthogonal to the main shrinkage direction of the laminated sheet are arranged linearly along the main shrinkage direction and moved in the same direction so that tension is also applied in the direction orthogonal to the main shrinkage direction of the laminated sheet. Fixed with multiple possible clips. The laminated sheet is heated at 170 ° C. for 1 minute, and the length in the uniaxial shrinkage direction (= Y direction) of the laminated sheet after heating is 43% of the length in the main shrinking direction of the laminated sheet before heating (that is, The tension applied to the laminated sheet was adjusted such that the length in the X direction was 97% of the laminated sheet before heating (ie, the shrinkage was 3%).

  Thereby, on the surface of the surface smooth hard layer, a plurality of protrusions are arranged along the contraction direction (Y direction), and a plurality of protrusions are formed on the surface of the first uneven pattern. A concavo-convex pattern including the second concavo-convex pattern formed by arranging the protrusions along the Y direction was formed to obtain an anisotropic light diffusion sheet.

  An uncured ultraviolet curable resin A (acrylate resin, manufactured by Soken Chemical Co., Ltd.) containing a release agent is formed to have a thickness of 20 μm on the concavo-convex pattern forming surface of the anisotropic light diffusion sheet obtained by the above method. A transparent PET substrate (A4300 manufactured by Toyobo Co., Ltd., thickness: 188 μm) is pressed thereon and irradiated with ultraviolet rays from the surface of the transparent PET substrate that is not in contact with the ultraviolet curable resin A. After the ultraviolet curable resin A was cured, the anisotropic light diffusion sheet was peeled off to obtain a primary transfer product having a pattern in which the uneven pattern of the anisotropic light diffusion sheet was reversed.

  Next, an uncured UV curable resin B (acrylate resin, manufactured by Sony Chemical Co., Ltd.) was applied to one side of a transparent PET substrate (A4300 manufactured by Toyobo Co., Ltd., thickness 188 μm) to a thickness of 20 μm. The surface having the reverse pattern of the primary transfer product is pressed against the ultraviolet curable resin B, and cured by irradiating ultraviolet rays from the surface of the transparent PET base material that is not in contact with the ultraviolet curable resin B. I let you. After curing, the primary transfer product is peeled off to obtain a secondary transfer product having the same uneven pattern as the anisotropic light diffusing sheet in which a surface layer made of a cured product of an ultraviolet curable resin is formed on a transparent PET substrate. It was.

(Example 2)
The same operation as in Example 1 except that the tension applied to the laminated sheet was adjusted so that the length in the X direction of the laminated sheet was 93% of the laminated sheet before heating (that is, the shrinkage rate was 7%). Thus, a secondary transfer product of the anisotropic light diffusion sheet was obtained.

(Example 3)
In place of the transparent PET base material and the ultraviolet curable resin A, a nickel electroforming stamper having a pattern in which the uneven pattern of the anisotropic light diffusing sheet is reversed by nickel electroforming is used, and the nickel electroforming stamper is used as a primary transfer product. A secondary transfer product of an anisotropic light diffusion sheet was obtained in the same manner as in Example 1 except that.

(Comparative Example 1)
A secondary transfer product of the anisotropic light diffusing sheet is obtained in the same manner as in Example 1 except that the hard layer forming coating material is changed to one obtained by diluting an acrylic resin having a glass transition temperature of 128 ° C. with toluene. It was.

(Comparative Example 2)
A secondary transfer product of an anisotropic light diffusing sheet is obtained in the same manner as in Example 1 except that the hard layer forming coating material is changed to one obtained by diluting an acrylic resin having a glass transition temperature of 139 ° C. with toluene. It was.

(Comparative Example 3)
The heating temperature of the laminated sheet is changed to 150 ° C., and the length in the uniaxial shrinkage direction (= Y direction) of the laminated sheet after heating is 65% of the length in the main shrinking direction of the laminated sheet before heating (that is, A secondary transfer product of the anisotropic light diffusion sheet was obtained in the same manner as in Example 1 except that the tension applied to the laminated sheet was adjusted so that the shrinkage rate was 35%.

(Comparative Example 4)
The same as in Example 1 except that the tension applied to the laminated sheet was adjusted so that the length in the X direction of the laminated sheet was the same length as the laminated sheet before heating (that is, the shrinkage rate was 0%). By operation, a secondary transfer product of the anisotropic light diffusion sheet was obtained.

(Comparative Example 5)
The same operation as in Example 1 except that the tension applied to the laminated sheet was adjusted so that the length in the X direction of the laminated sheet was 85% of the laminated sheet before heating (that is, the shrinkage rate was 15%). Thus, a secondary transfer product of the anisotropic light diffusion sheet was obtained.

<Surface characteristics of uneven pattern>
When the anisotropic light diffusion sheets of Examples 1 to 3 and Comparative Examples 3 to 5 were observed with a microscope, it was confirmed that the second uneven pattern was formed on the surface of the first uneven pattern.
When the anisotropic light diffusion sheets of Comparative Examples 1 and 2 were observed with a microscope, it was confirmed that the second uneven pattern was not formed on the surface of the first uneven pattern.

In each example, the most frequent pitch P ₁ , aspect ratio A ₁ and orientation degree C ₁ of the first uneven pattern, the most frequent pitch P ₂ , aspect ratio A ₂ and orientation degree C _{2 of} the second uneven pattern, The difference between the orientation direction of the first concavo-convex pattern and the orientation direction of the second concavo-convex pattern (abbreviated as “difference in orientation direction” in the table) was measured by the method described above. The specifications of the electron microscope used and the observation conditions are as follows.
Electron microscope: Hitachi High-Technologies S-3600N
Resolution: 3.0 nm (secondary electron image), 4.5 nm (reflected electron image),
Acceleration voltage: 0.5-30 kV, magnification: 12-300,000
Observation conditions: acceleration voltage 15 kV, working distance 10 mm
Table 1 shows the measurement results of the mode pitch, the aspect ratio, the degree of orientation, and the difference in orientation direction.

[Measurement of the most frequent pitch]
In accordance with the method described above, the most frequent pitches P ₁ and P ₂ were calculated.

[Aspect ratio measurement]
Along the above method was calculated aspect ratio A ₁ and A _2.

[Measurement of degree of orientation]
The orientation degrees C ₁ and C ₂ were calculated according to the method described above.

[Difference in orientation direction]
A difference in orientation direction was calculated along the method described above.

<Measurement of 1/10 value angle>
An illuminance curve was obtained by measuring transmitted scattered light using a goniometer (model: GENESIA Gonio / FFP, manufactured by Genesia). Specifically, when the measurement light of the anisotropic light diffusing sheet is incident from the direction having the first concavo-convex pattern and emitted from the surface opposite to the surface having the first concavo-convex pattern, The relative illuminance when the illuminance of this light is 0 °) is set to 1, and the relative illuminance from the light emission angle of −90 ° to 90 ° along the Y direction is measured at intervals of 1 °. An illuminance curve was obtained. Here, the illuminance curve is a curve plotted as shown in FIG. 11 with the horizontal axis as the light emission angle and the vertical axis as the relative illuminance.
Then, a 1/10 value angle (W _{2 in} FIG. 11) in the illuminance curve was obtained.
Table 1 shows the measurement results of the 1/10 value angle.

<Evaluation of light diffusibility>
The evaluation method of the light diffusibility of the anisotropic light diffusion sheet of an Example and a comparative example is demonstrated.
As shown in FIG. 13, a condensing lens is disposed in the light output portion of the LED light source (irradiation angle: about 120 °), and the light that has passed through the condensing lens and becomes substantially parallel light is the first of the anisotropic light diffusion sheet. From the surface having the concavo-convex pattern, so that the axis of the substantially parallel light and the anisotropic light diffusion sheet surface are 90 °, and the light is emitted from the surface opposite to the surface having the first concavo-convex pattern, and the emitted light is emitted from the floor. Irradiated the surface.

Here, FIGS. 13A, 13B, and 13C are schematic views of how the light appears when the irradiation state of the light that has passed through the anisotropic light diffusion sheet is observed from the X direction, the Y direction, and the Z direction, respectively. It is.

Next, the illuminance at positions G, H, and I in FIG. 13-C was measured. At this time, the distance from the LED light source to the anisotropic diffusion sheet is 20 mm, the distance from the anisotropic diffusion sheet to the floor surface is 2.5 m, the position G is the intersection of the irradiation axis of the LED light source and the floor surface, position G The positions G, H, and I were set so that the distance between −H was 2.5 m and the distance between positions GI was 0.5 m.
The illuminance measurement results are shown in Table 1. Here, the illuminance in Table 1 is a relative value when the illuminance at the position G in Example 1 is 100.

The ellipse in FIG. 13-C is a region where it is desired to irradiate LED light. If the relative illuminance at positions H and I is 45 or more, the performance as an anisotropic diffusion sheet is excellent. When the anisotropic light diffusion sheets of Examples 1 to 3 were used, the relative illuminance at the positions H and I were both 45 or more, and the diffused LED light could be efficiently diffused to the area to be irradiated.
On the other hand, when the anisotropic light diffusing sheets of Comparative Examples 1 to 5 are used, the relative illuminance at either position H or I is less than 45, and the performance of efficiently diffusing to the area where the LED light is desired to be irradiated. It was insufficient.

  Since the anisotropic light diffusing sheet of the present invention has excellent light diffusing properties, it can be preferably used for irradiating light in a line or ellipse shape without loss by combination with an LED light source, a condensing lens or the like.

DESCRIPTION OF SYMBOLS 1 Anisotropic light diffusing sheet 10 Concave / convex pattern 11 1st uneven | corrugated pattern 11a Projection part 11b Concave part 12 2nd uneven | corrugated pattern 12a Projection part 12b Concave part 13 LED light source 14 Condensing lens 15 Spread of light

Claims (6)

One side of the sheet has a first concavo-convex pattern formed by repeating undulations along one direction Y, and the undulations are repeated along the direction Y on the surface of the first concavo-convex pattern. An anisotropic diffusion sheet having a second concavo-convex pattern formed by meandering, wherein the first and second concavo-convex patterns meander when viewed from the surface, The 1/10 value angle when light enters from the surface having the first and second uneven patterns of the diffusion sheet and exits from the surface opposite to the surface having the first and second uneven patterns is the direction Y. An anisotropic light diffusing sheet characterized in that it exceeds 80 ° and is 5 to 15 ° in the X direction orthogonal to the direction Y. 2. The anisotropic light diffusion sheet according to claim 1, wherein the first concavo-convex pattern has an orientation degree of 0.2 to 0.5, and the second concavo-convex pattern has an orientation degree of 0.2 to 0.5. The anisotropic light diffusion sheet according to claim 1, wherein a difference between the orientation direction of the first uneven pattern and the orientation direction of the second uneven pattern is within 5 °. The anisotropic light diffusion sheet according to any one of claims 1 to 3, wherein the mode pitch of the first concavo-convex pattern is 3 to 20 µm, and the mode pitch of the second concavo-convex pattern is 0.3 to 2.0 µm. The light diffusion which injects substantially parallel light into the surface in which the said 1st uneven | corrugated pattern was formed of the anisotropic light diffusion sheet in any one of Claims 1-4, and radiate | emits from the surface in which the said 1st uneven | corrugated pattern is not formed Method. The light diffusing method according to claim 5, wherein an angle formed between a surface of the anisotropic light diffusing sheet and an optical axis of the substantially parallel light is in a range of 60 to 90 degrees.

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