JP2012111086A - Irregular pattern formation sheet, method of manufacturing the same, process sheet original plate for duplicating the irregular pattern formation sheet and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an irregular pattern formation sheet capable of obtaining an optical element preventing uneven brightness.SOLUTION: In the irregular pattern formation sheet, an irregular pattern in which projections are repeatedly formed to repeat irregularities along one direction Y is provided on at least one face. In a cross section of the irregular pattern cut along the direction Y, a non-shrunk region ratio α(%): α=(A-C)/A×100(%) is set to be 50% or less, wherein a measurement length A is a most frequent pitch P×100, high projecting parts 11c are first to fiftieth projections in descending order of height out of projections 11a located within a range of the measurement length A, an average shrunk height B is an average height of the projections serving as the high projecting parts 11c, a shrunk region 11d is a region where projections each having a height 10% or more of the average shrunk height B out of the projections 11a located within the range of the measurement length A, and a shrunk width C is a total of widths of the respective shrunk regions 11d.

Description

  The present invention relates to a concavo-convex pattern forming sheet having a concavo-convex pattern on at least one surface and a method for producing the same. Moreover, it is related with the process sheet | seat original plate used when copying an uneven | corrugated pattern formation sheet. Furthermore, it is related with the manufacturing method of an optical element.

An uneven pattern forming sheet in which an uneven pattern is formed on at least one surface of an optical element (for example, an antireflection body, a wire grid polarizer, a light diffuser, an optical phase difference body, etc.) used for a thin display or the like. Is widely used.
As a method for producing a concavo-convex pattern forming sheet, a method in which a heat-shrinkable resin film is heated and contracted after a hard layer is formed on at least one surface of the heat-shrinkable resin film has been proposed (Patent Documents 1 and 2).

JP 2008-302591 A JP 2008-201029 A

However, when the uneven | corrugated pattern formation sheet of patent document 1, 2 is used as an optical element, the nonuniformity may arise in the brightness.
Then, an object of this invention is to provide the uneven | corrugated pattern formation sheet and duplication process sheet | seat from which the optical element which does not produce unevenness in brightness easily is obtained, and manufacturing methods thereof.

  The inventor has found that in the uneven pattern forming sheet described in Patent Documents 1 and 2, there is an unshrinked region, and that the unshrinked region has periodicity causes uneven brightness. As a result of the study, the inventors have invented a concavo-convex pattern forming sheet and a method for producing the same, a process sheet master for duplicating the concavo-convex pattern forming sheet, and an optical element.

The present invention has the following aspects.
[1] A concavo-convex pattern forming sheet having a concavo-convex pattern in which convex portions are repeatedly formed so that the concavo-convex portion repeats along one direction Y,
The concavo-convex pattern forming sheet is characterized in that, in a cross section cut along the direction Y, an uncontracted area ratio α defined below is 50% or less.
The most frequent pitch P of the unevenness is a value obtained from an expression of 1 / {√ (X _Fmax ² + Y _Fmax ² )}. Here, X _Fmax and Y _Fmax are graphs obtained by smoothing the frequency (Z _F ) of a Fourier transform image obtained by two-dimensional Fourier transform of a grayscale image of a concavo-convex pattern. It is a position (X _Fmax , Y _Fmax ) indicating the maximum frequency other than.
Measurement length A: Mode pitch P × 100
High convex part: 1st to 50th convex part from the higher one among convex parts existing within the range of the measurement length A Average shrinkage height B: Average height of the convex part which is a high convex part Shrinkage Area: Area in which convex portions having a height of 10% or more of the average shrinkage height B among the convex portions existing within the range of the measurement length A are present. Shrinkage width C: total width of each shrinkage region Area ratio α (%): α = (A−C) / A × 100 (%)
[2] The uneven pattern forming sheet according to [1], wherein the average shrinkage height B of the high protrusions of the uneven pattern is 40% or less of the most frequent pitch P.
[3] The concavo-convex pattern forming sheet according to [1] or [2], wherein the most frequent pitch P is more than 1 μm and 20 μm or less.
[4] A laminated film manufacturing step of obtaining a laminated film by providing at least one hard layer having a smooth surface on at least one surface of the heat-shrinkable resin film, and heating the laminated film to shrink the heat-shrinkable resin film. Thus, the heat shrinking step of deforming the hard layer so as to be folded to form a concavo-convex pattern, and the stretching step of stretching the laminated film formed with the concavo-convex pattern in a direction opposite to the shrinking direction in the heat shrinking step. A method for producing a concavo-convex pattern forming sheet, comprising:
[5] at least a laminated film manufacturing process one side surface to obtain a laminated film provided at least one layer of smooth hard layer of heat shrinkable resin film, annealing step of annealing by heating the laminated film at a temperature T ₁ of Then, the annealed laminated film is heated at a temperature T ₂ (where T ₂ > T ₁ ) to shrink the heat-shrinkable resin film, thereby deforming the hard layer so as to be folded, thereby forming a concavo-convex pattern. A method for producing a concavo-convex pattern forming sheet, comprising: a heat shrinking step to be formed.
[6] The hard layer has a glass transition temperature Tg ₂ is described comprising the heat shrinking resin film 10 ° C. or more higher than the resin above the glass transition temperature Tg ₁ of the resin constituting the [4] or [5] Manufacturing method of uneven | corrugated pattern formation sheet.
[7] The method for producing a concavo-convex pattern forming sheet according to [4] or [5], wherein the hard layer is made of a metal or a metal compound.
[8] As a mold for producing a duplication sheet comprising the concavo-convex pattern forming sheet according to [1], and having a concavo-convex pattern having the most frequent pitch and average shrinkage height equivalent to the concavo-convex pattern forming sheet. The process sheet master for duplication used.
[9] An optical element comprising the uneven pattern forming sheet according to [1].

According to the concavo-convex pattern forming sheet and the duplication process sheet of the present invention, an optical element in which unevenness in brightness does not easily occur can be obtained.
According to the method for producing a concavo-convex pattern forming sheet of the present invention, the concavo-convex pattern forming sheet can be easily produced.
The optical element of the present invention is less likely to cause unevenness in brightness.

It is an expansion perspective view which shows one Embodiment of the uneven | corrugated pattern formation sheet of this invention. It is the figure which expanded the cross section at the time of cut | disconnecting the uneven | corrugated pattern formation sheet of FIG. It is sectional drawing at the time of cut | disconnecting the uneven | corrugated pattern formation sheet of FIG. 1 in the direction Y, Comprising: It is a figure explaining a shrinkage | contraction area | region. It is a graph which shows distribution of the pitch in an example of an uneven | corrugated pattern. It is sectional drawing at the time of cut | disconnecting the uneven | corrugated pattern formation sheet in which an unshrinkable area ratio exceeds 50% in the direction Y. FIG. It is sectional drawing which shows an example of a surface emitting unit.

<Uneven pattern forming sheet>
An embodiment of the uneven pattern forming sheet of the present invention will be described.
In FIG. 1, the perspective view of the uneven | corrugated pattern formation sheet of this embodiment is shown. The uneven | corrugated pattern formation sheet 10 of this embodiment has the uneven | corrugated pattern 11 on one surface. Here, the concavo-convex pattern 11 is a wave pattern in which the convex portions 11 a are repeatedly formed so that the concave and convex portions (the convex portions 11 a and the concave portions 11 b) are repeated along the one direction Y. In this specification, the convex part 11a is a convex part which exists between the bottom of the recessed part 11b to the bottom of the adjacent recessed part 11b among unevenness | corrugations (refer FIG. 2).
Moreover, the uneven | corrugated pattern 11 in this embodiment has the front-end | tip of the convex part 11a rounded, and also the ridgeline of the uneven | corrugated pattern 11 meanders.
Moreover, the uneven | corrugated pattern formation sheet 10 is 50% or less of uncontracted area | region ratios defined below in the cross section (refer FIG. 3) which the uneven | corrugated pattern 11 cut | disconnected along the direction Y. FIG. Preferably it is 40% or less, More preferably, it is 30% or less. If it exceeds 50% of the unshrinked area ratio α of the concavo-convex pattern 11, it becomes difficult to obtain an optical element having no unevenness in brightness.
Moreover, it is preferable that the non-shrinkable region ratio α is 5% or more in that the uneven pattern 11 can be easily formed.

  The unshrinked area ratio α is obtained from the most frequent pitch P, the measurement length A, the average shrinkage height B, and the shrinkage width C described below.

The measurement length A is 100 times the most frequent pitch P of the unevenness of the uneven pattern 11.
The most frequent pitch P is a value obtained from the equation 1 / {√ (X _Fmax ² + Y _Fmax ² )}.
Specifically, the most frequent pitch P is obtained by the following method.
First, the upper surface and cross section of the concavo-convex pattern 11 are observed with a microscope. When the mode pitch P of the concavo-convex pattern 11 is predicted to be 1 μm or more, an optical microscope is used, and when the mode pitch P is predicted to be 1 μm or less, an atomic force microscope is used.
Subsequently, after converting the image of the concavo-convex structure obtained by microscopic observation into a gray scale image, two-dimensional Fourier transform is performed. The frequency (Z _F ) of the Fourier transform image is smoothed, and a position (X _Fmax , Y _Fmax ) indicating the maximum frequency other than the center of the Fourier transform image is obtained from the obtained graph. Then, the most frequent pitch P is _obtained from the expression of the most frequent pitch P = 1 / {√ {square root over (X _Fmax ² + Y _Fmax ² )}}.
The most frequent pitch P is substantially equal to the average pitch of high convex portions described later. The average pitch of the high protrusions is the average pitch of the 1st to 50th protrusions from the highest height among the protrusions existing within the range of the measurement length A.

The most frequent pitch P is preferably more than 1 μm and not more than 20 μm. If the most frequent pitch P is more than 1 μm and not more than 20 μm, a duplicate sheet obtained by transferring the concavo-convex pattern forming sheet 10 or the concavo-convex pattern 11 can be suitably used as a light diffuser.
In order to make the most frequent pitch P within the predetermined range, the thickness of the hard layer described later may be appropriately selected when the concave / convex pattern forming sheet 10 is manufactured.

The average shrinkage height B is the average height of the convex portions that are the high convex portions 11c.
The average shrinkage height B is obtained as follows. In other words, the top surface of the concavo-convex pattern 11 is observed with a microscope, and a sectional view (see FIG. 3) cut along the direction Y is obtained from the observation. The height of one convex portion 11a is ½ of the sum of the distances in the direction Z from the bottom of the two concave portions 11b, 11b on both sides to the peak of the convex portion 11a. That is, as shown in FIG. 2, the height b _i of one convex portion 11a is the same as the height L _i of the convex portion 11a measured from the bottom of the concave portion 11b on one side with respect to the convex portion 11a. When the height measured from the bottom of the recess 11b is R _i , b _i = (L _i + R _i ) / 2. In this way determine the height b _i of each convex section 11a. Further, among the convex portions 11a, 11a,... Existing in the range of the measurement length A, the first to 50th convex portions from the higher height are defined as high convex portions, and their heights are averaged. The average shrinkage height B is determined.

Further, the average shrinkage height B of the high protrusions 11c is preferably 10% or more of the most frequent pitch P (that is, the aspect ratio is 0.1 or more). When the average shrinkage height B of the high convex portion 11c is 10% or more of the most frequent pitch P, when the concave / convex pattern forming sheet 10 or a duplicate sheet obtained by transferring the concave / convex pattern 11 is used as an optical element, The target optical performance is further improved.
In addition, the average shrinkage height B is preferably 500% or less of the most frequent pitch P, and more preferably 100% or less from the viewpoint that the uneven pattern 11 can be easily formed.

The contraction width C is the sum of the widths (C ₁ ,..., C _n ) of each contraction region 11d. As shown in FIG. 3, the contraction region 11 d is a region where, among the projections 11 a existing within the range of the measurement length A, there is a projection whose height is 10% or more of the average contraction height B. . Moreover, in this specification, area | regions other than the shrinkage | contraction area | region 11d (The area | region where the convex part whose height is less than 10% of average shrinkage height B exists among the convex part 11a which exists in the range of the measurement length A) )) Is referred to as an uncontracted region 11e.
The width (C ₁ ,..., C _n ) of each contraction region 11d is preferably 0.5% or more of the measurement length A, more preferably 0.6% or more, and More preferably, it is 7% or more. If the width of the contraction region 11d is equal to or greater than the lower limit, unevenness in brightness can be further suppressed.

  The unshrinked area ratio α (%) is obtained from the formula [(measured length A−shrinkage width C) / measured length A] × 100 (%).

The average shrinkage height B of the high protrusions 11c existing in the shrinkage region 11d is preferably 40% or less of the most frequent pitch P (that is, the aspect ratio is 0.4 or less), and 35% or less (that is, the aspect ratio). 0.35 or less), more preferably 30% or less (that is, an aspect ratio of 0.3 or less). If the average shrinkage height B is 40% or less of the most frequent pitch P, high optical performance can be obtained when a concavo-convex pattern forming sheet 10 or a duplicate sheet obtained by transferring the concavo-convex pattern 11 is used as an optical element. Can do. For example, when used in a light diffuser, sufficient luminance can be obtained while increasing light diffusibility.
Further, the average shrinkage height B is 5% or more of the most frequent pitch P (that is, the aspect ratio is 0.05 or more) from the viewpoint that sufficient light diffusibility can be obtained when used as a light diffuser. Preferably, it is 10% or more (that is, an aspect ratio of 0.1 or more).

The concavo-convex pattern 11 in the present embodiment has meandering lines meandering. In this specification, the degree of meandering of the ridge lines of the concavo-convex pattern 11 is referred to as the degree of orientation. The greater the degree of orientation, the more uneven pitches meander.
Moreover, in the uneven | corrugated pattern 11, it is preferable that orientation degree is 0.15-0.5. If the degree of orientation is 0.15 to 0.5, a duplicate sheet obtained by transferring the concavo-convex pattern forming sheet 10 or the concavo-convex pattern 11 can be suitably used as an optical element.
In order to make the degree of orientation within the predetermined range, a method of appropriately selecting a shrinkage rate when manufacturing the concavo-convex pattern forming sheet 10, a method of adjusting a shrinkage stress by annealing treatment while appropriately selecting constraint conditions, and shrinkage Later, a method of stretching while appropriately selecting load conditions may be employed.

The degree of orientation, first, by using the Fourier transform image obtained when determining the most frequent pitch P, and creates a Fourier transform image rotated θ such that the maximum illuminance portion coincides on X _F axis. Next, a parallel auxiliary line Y ′ _F is drawn on the Y _F axis passing through (X _Fmax , Y _Fmax ), the auxiliary line Y ′ _F is taken as the horizontal axis, and the illuminance (Z _F axis) on the auxiliary line Y ′ _F is taken as the vertical axis. Y ' _F -Z _F diagram is created. Next, a Y " _F -Z _F diagram is created by dividing the Y ' _F axis value of the Y' _F -Z _F diagram by the reciprocal (1 / P) of the most frequent pitch P, and this Y" _F -Z _F diagram To obtain the half width W of the peak (the width of the peak at a height at which the frequency is half of the maximum value). This half width represents the degree of orientation.

The concavo-convex pattern forming sheet 10 may be a sheet itself obtained by a manufacturing method of the concavo-convex pattern forming sheet described later, or a duplicate sheet obtained by duplicating a sheet obtained by the manufacturing method of the concavo-convex pattern forming sheet as an original plate. May be.
When the concavo-convex pattern forming sheet 10 is a sheet itself obtained by the manufacturing method of the concavo-convex pattern forming sheet described later, it is usually composed of two layers, and when it is a duplicate sheet, it is usually composed of one layer. Is done.

In the concavo-convex pattern forming sheet 10 in which the uncontracted area ratio α of the concavo-convex pattern 11 is 50% or less, sub-peaks hardly occur in the distribution of pitches (see FIG. 4) with the horizontal axis representing the reciprocal of the pitch and the vertical axis representing the frequency. , The peak is substantially one.
As a result of investigations by the present inventors, when having a sub-peak, brightness is increased when the concavo-convex pattern forming sheet 10 having the concavo-convex pattern 11 is combined with another optical element having concavo-convex (for example, a prism sheet). It was found that unevenness was likely to occur. That is, when the sub-peak pitch is equal to a multiple of the concave / convex pitch of other optical elements, it has been found that brightness unevenness caused by interference occurs. Even if the uneven pattern forming sheet that has sub-peaks in the pitch distribution and whose sub-peak waveform is sharper than the main peak is used as an optical element of various backlight units, brightness unevenness that seems to be due to interference is reduced. I found it to happen.
Pitch of the sub-peak is a pitch P ₁ which appears when there are many unshrunk region 11e as shown in FIG. Thus, if lower non-shrinkage, and less likely to occur pitch P _1, as a result, was found to be suppressed unevenness in brightness.

<Method for producing uneven pattern forming sheet>
(First embodiment)
1st Embodiment of the manufacturing method of the said uneven | corrugated pattern formation sheet 10 is described.
The manufacturing method of the uneven | corrugated pattern formation sheet of this embodiment has a laminated | multilayer film preparation process, a heat shrink process, and an extending process.

[Laminated film production process]
The laminated film forming step in the present embodiment is a step in which at least one hard layer having a smooth surface (hereinafter referred to as “surface smooth hard layer”) is provided on one surface of the heat-shrinkable resin film to obtain a laminated film. is there. Here, the surface smooth hard layer is a layer having a centerline average roughness of 0.1 μm or less as described in JIS B0601, and is a layer that does not shrink under the condition of shrinking the heat-shrinkable resin film.

As the heat-shrinkable resin 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.
In this embodiment, a uniaxially stretched film is used 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.
As the heat-shrinkable resin film, a film having a shrinkage of preferably 20 to 90%, more preferably 35 to 75% is used. In the present specification, the shrinkage rate is (shrinkage rate [%]) = {(length before shrinkage) − (length after shrinkage)} / (length before shrinkage) × 100 (however, The length is the length of the heat shrinkable resin film in the shrinking direction). When the shrinkage rate is 20% or more, the uneven pattern forming sheet can be more easily produced. On the other hand, it is difficult to produce a heat-shrinkable resin film having a shrinkage ratio exceeding 90%.
Since the heat-shrinkable resin film can easily form a surface smooth hard layer, the surface is preferably flat. Here, “flat” means that the center line average roughness according to JIS B0601 is 0.1 μm or less.

The surface smooth hard layer may be made of a resin, or a metal or a metal compound.
The resin constituting the surface smooth hard layer is appropriately selected depending on the type of resin constituting the heat-shrinkable resin film. For example, polyvinyl alcohol, polystyrene, acrylic resin, styrene-acryl copolymer, styrene-acrylonitrile copolymer Polymers, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethersulfone, fluororesin, and the like can be used.
The glass transition temperature Tg _{2 of} a resin constituting the surface smooth hard layer (hereinafter referred to as “second resin”) and a resin constituting the heat shrinkable resin film (hereinafter referred to as “second resin”) can be easily formed. The difference (Tg ₂ −Tg ₁ ) from the glass transition temperature Tg ₁ of “first resin”) is preferably 10 ° C. or higher, more preferably 20 ° C. or higher, and 30 ° C. or higher. It is particularly preferred.

As a method of providing the surface smooth hard layer made of resin, a method of continuously applying a coating liquid containing a second resin to a heat-shrinkable resin film and drying it may be mentioned.
Examples of coating methods for the coating liquid 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, and spin coating. Examples thereof include coating and dip coating.
Examples of the drying method include a heat drying method using hot air, infrared rays, or the like.
Dry coating amount of the resin solution into the heat shrinking resin film, it is preferable that the 1 to 100 mg / ^{m 2.} If the dry coating amount of the resin solution is 1 mg / m ² or more, the uneven pattern can be sufficiently formed, and if it is 100 mg / m ² or less, the surface smooth hard layer can be easily thinned.

Examples of the metal constituting the smooth surface hard layer include gold, aluminum, silver, copper, germanium, indium, magnesium, niobium, palladium, lead, platinum, silicon, tin, titanium, vanadium, zinc, and bismuth.
Examples of the metal compound constituting the surface smooth hard layer include titanium oxide, aluminum oxide, zinc oxide, magnesium oxide, tin oxide, copper oxide, indium oxide, cadmium oxide, lead oxide, silicon oxide, barium fluoride, calcium fluoride, Examples include magnesium fluoride, zinc sulfide, and gallium arsenide.

  As a method for providing a smooth surface hard layer composed of a metal or a metal compound, a plating method, a vacuum deposition method, a sputtering method, an ion plating method, an ionization deposition method, an ion cluster beam deposition method, or the like can be appropriately employed.

[Heat shrinkage process]
The heat shrinking step is a step of forming a concavo-convex pattern by deforming the surface smooth hard layer so as to be folded by heating the laminated film and shrinking the heat shrinkable resin film.
In the heat shrinking step, it is preferable to shrink at a shrinkage rate of 40% or more. In this way, by setting the shrinkage rate to 40% or more, it is possible to form the concavo-convex pattern 11 with few unshrinked regions 11e. If the shrinkage rate is too high, the area of the resulting concavo-convex pattern forming sheet 10 becomes small, which is not preferable in terms of yield. From such a viewpoint, the upper limit of the shrinkage rate is preferably 80%.

Examples of the heating method include a method of passing through hot air, steam, or hot water. Among them, a method of passing through hot air is preferable because it can be uniformly contracted.
The heating temperature when the heat-shrinkable resin film is thermally shrunk depends on the type of heat-shrinkable resin film to be used, the most frequent pitch P of the target concavo-convex pattern 11 and the average shrinkage height B of the high convex portion 11c. It is preferable to select appropriately.
When the surface smooth hard layer is made of a resin (second resin), the heat shrinkage temperature is preferably a temperature equal to or higher than the glass transition temperature Tg ₁ of the first resin constituting the heat shrinkable resin film. When heat shrinking at a temperature of Tg ₁ or higher, the concave / convex pattern 11 can be easily formed.
Further, the heat shrinkage temperature is preferably less than (glass transition temperature Tg ₂ + 15 ° C. of the second resin).

  After the heat shrinking process, the shrunk laminated film is once wound up into a roll shape, and in the stretching process, the shrunk laminated film may be fed out from the roll, or the shrunk laminated film is stretched as it is without being wound. You may supply to a process. In the case of winding the contracted laminated film once, the production of the uneven pattern forming sheet can be made flexible. When the contracted laminated film is supplied to the stretching process as it is without being wound, the laminated film can be supplied from the heat shrinking process to the stretching process without lowering the temperature, so that there is little energy loss.

[Stretching process]
The stretching step is a step of stretching the laminated film on which the concavo-convex pattern has been formed through the heat shrinking step in a direction opposite to the shrinking direction in the heat shrinking step.
Examples of the stretching method include a tenter method and a roll method. Here, the tenter method is a method using a stretching apparatus having a pair of clips that are separated from each other, and is a method of stretching the film by attaching the pair of clips to a film and separating them from each other. The roll method is a method that uses a stretching device that includes a plurality of sandwiching means having a pair of rolls and that has a faster rotating speed of the roll of the sandwiching means as it goes downstream, and is a method of stretching a film through a plurality of sandwiching means sequentially. is there.
In stretching, it is preferable to heat appropriately in order to facilitate stretching. Since the heating temperature at the time of stretching can be easily stretched, it is preferably not less than the glass transition temperature Tg ₁ of the heat-shrinkable resin film.
The draw ratio in the stretching step is not particularly limited, and is usually set within a range of 1 to 5 times.

[Function and effect]
As a result of investigations by the present inventors, it has been found that the non-shrinkable region 11e decreases as the shrinkage rate increases. Further, it has been found that even when the uneven pattern 11 having a small amount of the non-shrinkable region 11e is stretched by the stretching process, a new non-shrinkable region 11e is hardly generated. Therefore, if the shrinkage is excessively performed in the heat shrinking step, the non-shrinkable region 11e can be reduced, and if the shrinkage rate is lowered in the stretching step, the target shrinkage rate can be easily adjusted.
Therefore, according to the manufacturing method of this embodiment, the uneven | corrugated pattern formation sheet 10 with few uncontracted area | regions 11e can be manufactured easily.

<Second Embodiment>
2nd Embodiment of the manufacturing method of the uneven | corrugated pattern formation sheet of this invention is described.
The manufacturing method of the uneven | corrugated pattern formation sheet of this embodiment is a method which has a laminated | multilayer film preparation process, an annealing process, and a heat contraction process.
The laminated film production process in the present embodiment is the same as the laminated film production process in the first embodiment.

[Annealing process]
Annealing step is a step of annealing (thermal relaxation treatment) a laminated film obtained by laminating a film manufacturing process by heating at a temperature T _1.
The annealing temperature T ₁ is set to a temperature lower than the temperature T ₂ heated in the heat shrinking step. If T ₁ is T ₂ or more, the uneven pattern may be non-uniform.
Further, T ₁ is preferably less than T ₂ , more preferably 5 ° C. or more, and more preferably 10 ° C. or more.
Examples of the heating method include a heating method using hot air and a heating method using infrared irradiation.
During the annealing treatment, it is preferable to fix the laminated film at both ends in the shrinking direction so that the laminated film shrinks and the dimensions do not change.

  After the annealing step, the annealed laminated film may be wound up into a roll and the annealed laminated film may be unwound from the roll in the heat shrinking process, or the annealed laminated film may be heated as it is without being wound. You may supply to a contraction process. When the laminated film that has been annealed is wound up, the production of the uneven pattern forming sheet can be made flexible. When the annealed laminated film is supplied as it is to the heat shrinking process without being rolled up, the laminated film can be supplied from the annealing process to the heat shrinking process without lowering the temperature, so that there is little energy loss.

[Heat shrinkage process]
In the heat shrinking process in the present embodiment, as in the heat shrinking process in the first embodiment, the laminated film is heated to shrink the heat shrinkable resin film so that the surface smooth hard layer is folded. A concavo-convex pattern is formed by deformation.
In the present embodiment, it is preferable to contract at a shrinkage rate of 20 to 50% in the heat shrinking step. If the shrinkage rate is set to the lower limit value or more, the non-shrinkable region 11e can be reduced, and if the shrinkage rate is set to the upper limit value or less, sufficient luminance can be obtained while increasing the light diffusibility.
The heating method at the time of heat shrinkage is the same as the heat shrinkage step in the first embodiment.
When the surface smooth hard layer is made of a resin (second resin), the heat shrinkage temperature is the glass transition temperature Tg ₂ of the second resin and the glass transition temperature of the first resin constituting the heat shrinkable resin film. A temperature between Tg ₁ is preferable. As described above, when the heat shrinkage is performed at a temperature between Tg ₂ and Tg ₁ , the uneven pattern 11 can be easily formed.

[Function and effect]
In the manufacturing method of this embodiment, since the laminated film is annealed, it is possible to relieve the stress generated in the portion that tends to shrink. Thereby, shrinkage | contraction property can be equalized over the whole laminated | multilayer film. Therefore, the uneven | corrugated pattern formation sheet with few non-shrinkable areas can be manufactured easily.

<Draft pattern forming sheet duplication process sheet master>
The process sheet original plate for duplication (hereinafter referred to as process sheet original plate) of the present invention is provided with the uneven pattern forming sheet 10 described above. In addition, the process sheet original plate may further include a resin or metal support for supporting the uneven pattern forming sheet 10.
This process sheet original plate can be used as a mold for producing a large number of duplicate sheets having a concavo-convex pattern having the most frequent pitch and average shrinkage height on the surface equivalent to the process sheet original plate.

Specific methods for producing a duplicate sheet using the process sheet precursor include, for example, the following methods (a) to (c).
(A) After applying the uncured active energy ray curable resin to the surface on which the uneven pattern 11 of the uneven pattern forming sheet 10 is formed and irradiating the active energy ray to cure the curable resin And a step of peeling the cured coating film from the concavo-convex pattern forming sheet 10. Here, the active energy ray is usually an ultraviolet ray or an electron beam, but in this specification, it includes a visible ray, an X-ray, an ion beam, and the like.
(B) A step of applying an uncured liquid thermosetting resin to the surface of the uneven pattern forming sheet 10 on which the uneven pattern 11 is formed, and heating to cure the liquid thermosetting resin, and then curing. And a step of peeling the coating film from the concavo-convex pattern forming sheet 10.
(C) A step of bringing the sheet-shaped thermoplastic resin into contact with the surface of the uneven pattern forming sheet 10 on which the uneven pattern 11 is formed, and heating the sheet-shaped thermoplastic resin while pressing the uneven pattern forming sheet 10. A process of cooling after softening, and a process of peeling the cooled sheet-like thermoplastic resin from the concavo-convex pattern forming sheet 10.

Further, by using the concavo-convex pattern forming sheet 10, a metal or other secondary process molded product to which the concavo-convex pattern 11 of the concavo-convex pattern forming sheet 10 is transferred is prepared, and the secondary process molded product is formed into a mold (stamper). ) Can be used to produce a resinous sheet-like replica sheet. As the molded product for the secondary process, the concavo-convex pattern forming sheet 10 is rolled into a cylindrical shape so that the concavo-convex pattern 11 is inside, and is attached to the inside of the cylinder, and a roll is inserted inside the cylinder. Examples thereof include a plating roll obtained by plating and taking out from a cylinder. Examples of other secondary process moldings include sheet-like secondary process sheets.
Specific methods using the molded product for the secondary process include the following methods (d) to (f).

(D) A step of laminating a plating layer (a material for transferring the uneven pattern) on the surface of the uneven pattern forming sheet 10 on which the uneven pattern 11 is formed, and depositing a plating layer (an uneven pattern transfer material); Peeling from the sheet, producing a metal secondary process molding, and then on the side in contact with the concave / convex pattern of the secondary process molding (surface with the concave / convex pattern transferred), A step of applying an uncured active energy ray-curable resin; and a step of irradiating the active energy ray to cure the curable resin and then peeling the cured coating film from the molded product for the secondary step. Method.
(E) A step of laminating a plating layer (a material for transferring the concavo-convex pattern) on the surface of the concavo-convex pattern forming sheet 10 on which the concavo-convex pattern 11 is formed; The step of preparing the molded product for the secondary process and an uncured liquid thermosetting resin on the surface (the surface on which the concavo-convex pattern was transferred) that was in contact with the concavo-convex pattern of the molded product for the secondary process The method which has the process of apply | coating, and the process which peels the hardened coating film from the molding for secondary processes, after hardening this resin by heating.
(F) A step of laminating a plating layer (a material for transferring the concavo-convex pattern) on the surface of the concavo-convex pattern forming sheet 10 on which the concavo-convex pattern 11 is formed; The sheet-shaped thermoplastic resin is brought into contact with the step of producing the molded product for the secondary process and the surface of the molded product for the secondary process that is in contact with the concave-convex pattern (the surface on which the concave-convex pattern is transferred). A process, a step of heating and softening the sheet-shaped thermoplastic resin while pressing it against a molded product for a secondary process, and a cooling process; and molding the cooled sheet-shaped thermoplastic resin for a secondary process And a step of peeling from the substrate. Alternatively, a step of bringing a molten thermoplastic resin into contact with the surface (the surface on which the concavo-convex pattern has been transferred) that has been in contact with the concavo-convex pattern of the molded product for the secondary process produced by the same method as described above, and melting The method which has the process of cooling the thermoplastic resin of a state into a sheet form, and the process of peeling the cooled sheet-like thermoplastic resin from the molding for secondary processes.

  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 uneven pattern forming sheet 10 on which the uneven pattern 11 is formed. The application method mentioned when the hard layer consists of resin can be used for the application method. Next, the concavo-convex pattern forming sheet 10 coated with the curable resin is pressed by passing between a pair of rolls, and the curable resin is filled into the concavo-convex pattern 11 of the concavo-convex pattern forming sheet 10. Then, an active energy ray is irradiated with an active energy ray irradiation apparatus, and curable resin is bridge | crosslinked and hardened. And a duplicate sheet | seat can be manufactured by peeling the active energy ray curable resin after hardening from the uneven | corrugated pattern formation sheet 10. FIG.

In the method (a), the surface of the concavo-convex pattern forming sheet 10 on which the concavo-convex pattern 11 is formed is provided with a silicone resin, fluorine before application of an uncured active energy ray curable resin for the purpose of imparting releasability. A layer made of resin or the like may be provided with a thickness of about 1 to 10 nm.
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.
In addition, in the uncured active energy ray-curable resin, at least one of a polyfunctional (meth) acrylate monomer and an oligomer may be used for the purpose of increasing the hardness after curing. Moreover, you may contain a reactive inorganic oxide particle and / or a reactive organic particle.

  After applying an uncured liquid active energy ray-curable resin, an active energy ray may be irradiated after bonding a bonding substrate made of resin, glass or the like. Irradiation of the active energy ray may be performed from any one of the bonding base material and the concavo-convex pattern forming sheet 10 having active energy ray permeability.

  The thickness of the cured active energy ray-curable resin sheet is preferably 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 said method, since the web-shaped thing is used as the uneven | corrugated pattern formation sheet 10, the uneven | corrugated pattern 11 can be continuously formed in a large area. Therefore, even if the number of times the concavo-convex pattern forming sheet 10 is repeatedly used is small, a necessary amount of the sheet-like replica sheet can be manufactured in a short time.
The uneven pattern forming sheet 10 may be a single sheet. 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 uneven | corrugated pattern formation sheet 10 inside the type | mold of an injection molding machine.

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 concavo-convex pattern forming sheet 10. This is because if the curing temperature is equal to or higher than the glass transition temperature of the uneven pattern forming sheet 10, the uneven pattern 11 of the duplicate 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 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 concavo-convex pattern forming sheet 10. It is because the uneven | corrugated pattern 11 of the uneven | corrugated pattern formation sheet 10 may deform | transform at the time of heating that heating temperature is more than the glass transition temperature of the uneven | corrugated pattern formation sheet 10. FIG.
The cooling temperature after heating is preferably less than the glass transition temperature of the thermoplastic resin because the uneven pattern 11 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 11 of the uneven pattern forming sheet 10 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), since a replica sheet is manufactured using a metal secondary process molded product with small deformation due to heat as a mold, active energy rays are used as a material for the replica sheet. Any of a curable resin, a thermosetting resin, and a thermoplastic resin can be suitably used.

  In addition, in (d)-(f), although the metal thing was used as the molded object for secondary processes, the uneven | corrugated pattern 11 of the uneven | corrugated pattern formation sheet 10 is transcribe | transferred to resin, and it is for resin-made secondary processes. A molded product may be obtained. 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 the thus obtained resin sheet-like replica sheet, the uneven pattern 11 may be formed on the surface opposite to the surface to which the uneven pattern 11 is transferred.

<Optical element>
The optical element of the present invention is provided with the above uneven pattern forming sheet. The concavo-convex pattern forming sheet used for the optical element may be a concavo-convex pattern forming sheet obtained by the manufacturing method of the first or second embodiment, or a duplicate sheet obtained using the concavo-convex pattern forming sheet as an original plate. Also good.
As an optical element, it is used for a light-diffusion body, an antireflection body, a wire grid polarizer, a phase difference plate etc., for example. In particular, a light diffuser and an antireflective body are mentioned.

(Light diffuser)
In the concavo-convex pattern forming sheet 10, the concavo-convex pattern 11 having a mode pitch P exceeding 1 μm exhibits light diffusibility and can be used as a light diffuser.
That is, since the surface of the concavo-convex pattern forming sheet 10 has corrugated irregularities, light passing through the concavo-convex pattern forming sheet is refracted by the concavo-convex surface, and is thus emitted from the light diffuser at various emission angles. . Accordingly, the light diffusibility is expressed by the uneven pattern 11.

Moreover, when using the uneven | corrugated pattern formation sheet 10 for a light diffuser, only the uneven | corrugated pattern formation sheet 10 may be sufficient, but another layer may be provided in the single side | surface or both surfaces of the uneven | corrugated pattern formation sheet 10. . For example, an antifouling layer having a thickness of about 1 to 5 nm containing a fluororesin or a silicone resin as a main component may be provided on the surface on which the concave / convex pattern 11 is formed in order to prevent the surface from being stained. Good.
In addition, a transparent resin or glass support may be provided on the surface on which the uneven pattern 11 is not formed. Furthermore, a pressure-sensitive adhesive layer may be formed on the surface on which the concave / convex pattern 11 is not formed, and a dye may be included to appropriately provide functionality.
The light diffuser provided with the uneven pattern forming sheet 10 on which the uneven pattern 11 described above is formed has excellent anisotropy.

  In the case of a light diffuser, the most suitable pitch of the uneven pattern 11 is preferably 1 to 20 μm. Moreover, a suitable average shrinkage height is 0.1-10 micrometers.

In the light diffuser, for the purpose of further enhancing the light diffusion effect, a concave / convex pattern is formed with a light diffusing agent composed of an inorganic compound and an organic light diffusing agent composed of an organic compound within a range that does not significantly impair optical performance such as light transmittance. It can be contained in the sheet.
Examples of the inorganic light diffusing agent include silica, white carbon, talc, magnesium oxide, zinc oxide, titanium oxide, calcium carbonate, aluminum hydroxide, barium sulfate, glass, mica and the like.
Examples of the organic light diffusing agent include styrene polymer particles, acrylic polymer particles, and siloxane polymer particles. These light diffusing agents can be used alone or in combination of two or more.
The content of the light diffusing agent is preferably 10 parts by mass or less with respect to 100 parts by mass of the resin constituting the concavo-convex pattern forming sheet 10 because it is difficult to impair the light transmittance.

Moreover, the uneven | corrugated pattern formation sheet 10 used as a light diffuser can contain a fine bubble within the range which does not impair optical performance, such as a light transmittance, for the purpose of improving a diffusion effect more. The fine bubbles have little light absorption and are difficult to reduce the light transmittance.
As a method for forming fine bubbles, a method of mixing a foaming agent into a concavo-convex pattern forming sheet (for example, a method disclosed in JP-A-5-212811 and JP-A-6-107842), or an acrylic foamed resin is used. A method (for example, a method disclosed in Japanese Patent Application Laid-Open No. 2004-2812) including foaming treatment and containing fine bubbles can be applied. Furthermore, a method of causing fine bubbles to foam non-uniformly at a specific position (for example, a method disclosed in Japanese Patent Application Laid-Open No. 2006-124499) is preferable in that more uniform surface irradiation is possible.
The light diffusing agent and fine foaming can be used in combination.

  In order to increase the diffusibility, a film containing fine bubbles may be attached to the side where the uneven pattern 11 is not formed.

The light diffusing body including the uneven pattern forming sheet 10 is used, for example, in a surface light emitting unit of a liquid crystal display device, a light emitting unit of a lighting device, or the like.
FIG. 6 shows an example of the surface light emitting unit. The surface light emitting unit 1 includes a light guide plate 20, a light source 30, a reflection plate 40, a condensing sheet 50, and a light diffuser 60, and the light diffuser 60 includes the uneven pattern forming sheet 10 described above.
In the surface light emitting unit 1, the light sources 30 are arranged on the one side surface 21 of the light guide plate 20 at equal intervals.
The reflection plate 40 is provided on the back surface 22 side of the light guide plate 20, reflects light leaked from the back surface 22 of the light guide plate 20, returns it to the light guide plate 20, and improves the light use efficiency.
The condensing sheet 50 is disposed on the light emitting side of the light guide plate 20 and has a concave and convex periodic structure. Light that is incident on the light incident surface 51 from an oblique direction stands in a direction perpendicular to the light emitting surface 52. Condensing function to raise and emit.
The light diffuser 60 is disposed on the light exit side of the light collecting sheet 50. In the light diffuser 60, since the brightness | luminance of the surface emitting unit 1 will fall if light diffusivity is too high, it is preferable to use what has moderate light diffusibility.

  Since the uneven | corrugated pattern formation sheet with which the light-diffusion body 60 is provided has few uncontracted area | regions and the light diffusibility (diffusion angle) about the direction Y is uniform, the nonuniformity of the brightness | luminance of the surface emitting unit 1 can be suppressed.

(Antireflection body)
In the concavo-convex pattern forming sheet 10, the concavo-convex pattern 11 having the most frequent pitch P of 1 μm or less exhibits antireflection properties and can be used as an antireflection body.
That is, the wavy uneven pattern 11 portion shows an intermediate refractive index between the refractive index of air and the refractive index of the uneven pattern forming sheet 10, and the intermediate refractive index changes continuously. For example, the mode P of the concavo-convex pattern 11 is set to 0.2 μm or less, and the average shrinkage height B of the concavo-convex pattern 11 is set to 10% or more when the mode P is 100%. The reflectance can be made particularly low, and specifically, the reflectance can be reduced to almost 0%. This is because the portion where the intermediate refractive index continuously changes becomes longer in the thickness direction, and the effect of suppressing light reflection is remarkably exhibited. The specific average shrinkage height B of the concavo-convex pattern 11 in the case of an antireflection body is preferably 0.01 to 0.4 μm.

The antireflection body may be the concavo-convex pattern forming sheet 10 alone, but may be provided with other layers on one or both sides of the concavo-convex pattern forming sheet. For example, in order to prevent the surface of the concave / convex pattern forming sheet 10 on the side where the concave / convex pattern 11 is formed, a thickness of about 1 to 5 nm containing a fluororesin or a silicone resin as a main component is prevented. An antifouling layer may be provided.
In addition, the surface on which the uneven pattern 11 is not formed may be provided with, for example, a resin sheet such as triacetyl cellulose as a base material of the antireflection body.

Such an antireflection body is attached to, for example, an image display device such as a liquid crystal display panel or a plasma display, a light emitting portion tip of a light emitting diode, a surface of a solar cell panel, or the like.
When it is attached to the image display device, it is possible to prevent reflection of illumination, so that the visibility of the image is improved. When it is attached to the tip of the light emitting part of the light emitting diode, the light extraction efficiency is improved. When it is attached to the surface of the solar cell panel, the amount of light taken in increases, so that the power generation efficiency of the solar cell is improved.

In addition, this invention is not limited to the said embodiment.
For example, the uneven pattern forming sheet may have an uneven pattern on both sides.
The unevenness of the uneven pattern may be linear without meandering. Even when the unevenness of the uneven pattern does not meander, the non-shrinkable area ratio is 50% or less, so that there is no sub-peak in the pitch distribution. Accordingly, interference with the uneven pitch of other optical elements (for example, a prism sheet or the like) can be suppressed, so that brightness unevenness hardly occurs.

Example 1
Polymethylmethacrylate (Polymer Source Co., Ltd.) diluted in toluene on one side of a heat-shrinkable film made of polyethylene terephthalate (Hishipet LX-10S manufactured by Mitsubishi Plastics, Inc., glass transition temperature 70 ° C.) having a thickness of 50 μm and thermally shrinking in a uniaxial direction P4831-MMA (manufactured by P4831-MMA, glass transition temperature 100 ° C.) was applied by a bar coater so as to have a thickness of 2 μm, and a hard layer was formed to obtain a laminated film.
Next, the laminated film was arranged so that the direction of shrinkage when heated was oriented in the vertical direction, and the upper and lower ends of the laminated film were fixed with a fixing jig so that the vertical dimension of the laminated film did not change. In this state, annealing was performed by heating at 85 ° C. for 2 minutes.
Next, the fixing jig was removed from the laminated film, and the laminated film was heated at 95 ° C. for 1 minute to heat shrink to 30% of the length before heating. Thereby, the uneven | corrugated pattern formation sheet which has the waveform uneven | corrugated pattern in which the unevenness | corrugation was repeatedly formed along one direction was obtained.
Next, nickel plating was applied to the surface on which the uneven pattern of the obtained uneven pattern forming sheet was formed, and the nickel plating was peeled off to obtain a nickel plating stamper having a thickness of 300 μm. An uncured ultraviolet curable resin composition containing an epoxy acrylate prepolymer, 2-ethylhexyl acrylate and a benzophenone photopolymerization initiator was applied to the surface of the nickel plating stamper on which the concavo-convex pattern was formed. Next, a polyethylene terephthalate film having a thickness of 100 μm was placed on the surface of the uncured UV curable resin composition coating film not in contact with the nickel plating stamper, and pressed to bring it into close contact.
Next, ultraviolet rays are irradiated from above the polyethylene terephthalate film, the uncured ultraviolet curable resin composition is cured, and the cured product thus obtained is peeled off from the nickel plating stamper stamper, thereby reproducing the uneven pattern forming sheet. Got.

(Example 2)
The laminated film obtained in the same manner as in Example 1 was heated at 105 ° C. for 2 minutes to cause heat shrinkage to 50% of the length before heating, and a corrugated shape in which irregularities were repeatedly formed along the shrinkage direction. A shrink sheet having an uneven pattern was obtained.
Next, the shrinkable sheet was placed so that the shrinkage direction was in the vertical direction, and fixing jigs were attached to the upper and lower ends of the shrinkable sheet. The fixing jig attached to the lower end of the shrinkable sheet was not allowed to move up and down, and the fixing jig attached to the lower end of the shrinkable sheet was allowed to move up and down. Subsequently, the fixing jig attached to the lower end of the shrinkable sheet was moved downward to perform a stretching process. At that time, the film was stretched so that the tensile load was 50 gf / cm ² , the temperature was 105 ° C., the stretching time was 3 minutes, and the final shrinkage was 20%. Thereby, the uneven | corrugated pattern formation sheet which has the waveform uneven | corrugated pattern in which the unevenness | corrugation was repeatedly formed along one direction was obtained.
A duplicate sheet of the uneven pattern forming sheet was obtained in the same manner as in Example 1 except that this uneven pattern forming sheet was used.

(Example 3)
A duplicated sheet of a concavo-convex pattern forming sheet was obtained in the same manner as in Example 2 except that the stretching time was 1 minute and the stretching process was performed so that the final shrinkage rate was 40%.

(Comparative Example 1)
The laminated film obtained in the same manner as in Example 1 was heated at 90 ° C. for 1 minute to cause heat shrinkage to 25% of the length before heating, and a wave shape in which irregularities were repeatedly formed along the shrinkage direction. The uneven | corrugated pattern formation sheet which has an uneven | corrugated pattern was obtained.
A duplicate sheet of the uneven pattern forming sheet was obtained in the same manner as in Example 1 except that this uneven pattern forming sheet was used.

About the uneven | corrugated pattern formed in each Example and each comparative example, the most frequent pitch P, the average shrinkage height B, the shrinkage width C, the unshrinkable area ratio α, and the aspect ratio (P / B) were measured by the following methods. . The results are shown in Table 1.
Moreover, the half-angle value and standard deviation of the diffusion angle of the uneven | corrugated pattern formation sheet of each Example and each comparative example were measured with the following method.
Moreover, as will be described later, a surface light emitting unit was prepared using the uneven pattern forming sheet of each example and each comparative example, and brightness unevenness and luminance of the surface light emitting unit were evaluated.

[Frequent pitch]
An image of the upper surface of the concavo-convex pattern was taken with a laser microscope, the image was converted into a gray scale image, and then two-dimensional Fourier transform was performed. The frequency (Z _F ) of the Fourier transform image is smoothed, and the mode pitch P = 1 / {√ (X _Fmax ) from the position (X _Fmax , Y _Fmax ) indicating the maximum frequency of the portion excluding the center of the Fourier transform image. ² + Y _Fmax ² )}.

[Non-shrinkage area ratio]
An image of the top surface of the concavo-convex pattern was taken with a laser microscope. At that time, the photographing magnification and the number of image captures were adjusted so that at least an image having a measurement distance A (= moderate pitch × 100) was obtained.
Next, among the convex portions existing within the range of the measurement length A, the first to 50th convex portions from the highest height are defined as high convex portions, and the average contraction height B ( The determination height B) of the unshrinked region was determined.
Subsequently, among the convex portions existing within the range of the measurement length A, the width of the contracted region where the convex portion having a height that is 10% or more of the average contracted height B is totaled to obtain the contracted width C. .
Then, the uncontracted area ratio α (%) was obtained from the formula [(measured length A−shrinkage width C) / measured length A] × 100 (%).

[aspect ratio]
The aspect ratio was determined from the equation of the most frequent pitch P / average shrinkage height B.

[Diffusion angle]
A commercially available mobile phone was disassembled, and a surface light emitting means having a light guide plate, a light emitting diode provided on one side of the light guide plate, and a light collecting sheet provided on the light emitting side of the light guide plate was recovered. . A concave / convex pattern forming sheet was attached to the light emitting side of the light collecting sheet of the surface light emitting means so that the concave / convex pattern was directed to the light emitting side to obtain a surface light emitting unit.
About the surface emitting unit, the half-value angle of the direction X orthogonal to the direction Y and the direction Y where an unevenness | corrugation is repeated was measured using GENESISA GonioFar Field Profiler (made by Genesia). Here, the half-value angle is the maximum intensity of light when the angle θ of light emitted in the Z direction from the light emitting surface is 0 ° and the angle of light emitted along the light emitting surface is 90 °. It is the range of angles where the intensity is more than half of the value. The larger the half-value angle, the higher the light diffusibility.
Further, the standard deviation of the diffusion angle in the direction Y was obtained. The standard deviation serves as an index of light diffusibility uniformity. The smaller the standard deviation, the higher the light diffusibility uniformity.

[Brightness unevenness]
The light emitting surface of the surface light emitting unit was observed at a distance of 10 to 15 cm from the light emitting surface with the light emitting diode turned on in the dark room, and the brightness unevenness was evaluated according to the following criteria.
○: Four or more of the five observers are determined to be non-uniform.
Δ: 3 out of 5 observers were determined to be non-uniform and 2 were determined to be non-uniform.
X: Three or more of the five observers are determined to be uneven.

[Luminance]
The front luminance of the surface emitting unit was measured using a luminance measuring device SR-3 (Topcon Co., Ltd.) with the light emitting diode turned on.

The duplicate sheet of the uneven pattern forming sheet of Examples 1 to 3 having an unshrinked area ratio α of 50% or less had a moderately high light diffusibility in the direction Y and the light diffusibility was uniform. Furthermore, in the surface emitting unit using these uneven | corrugated pattern formation sheets, the brightness nonuniformity was suppressed and it had sufficient brightness | luminance. In particular, Examples 1 and 2 in which the aspect ratio of the concavo-convex pattern was 0.40 or less had high luminance.
On the other hand, the light-diffusing property of the duplicated sheet of the uneven pattern forming sheet of Comparative Example 1 having an unshrinked area ratio α of 60% was non-uniform. In the surface light emitting unit using this uneven pattern forming sheet, unevenness in brightness was observed.

DESCRIPTION OF SYMBOLS 10 Asperity pattern formation sheet 11 Asperity pattern 11a Convex part 11b Concave part 11c High convex part 11d Contraction area 11e Non-contraction area | region

Claims (9)

A concavo-convex pattern forming sheet having a concavo-convex pattern in which convex portions are repeatedly formed so as to repeat the concavo-convex along one direction Y, on at least one surface,
The concavo-convex pattern forming sheet is characterized in that, in a cross section cut along the direction Y, an uncontracted area ratio α defined below is 50% or less.
The most frequent pitch P of the unevenness is a value obtained from an expression of 1 / {√ (X _Fmax ² + Y _Fmax ² )}. Here, X _Fmax and Y _Fmax are graphs obtained by smoothing the frequency (Z _F ) of a Fourier transform image obtained by two-dimensional Fourier transform of a grayscale image of a concavo-convex pattern. It is a position (X _Fmax , Y _Fmax ) indicating the maximum frequency other than.
Measurement length A: Mode pitch P × 100
High convex part: 1st to 50th convex part from the higher one among convex parts existing within the range of the measurement length A Average shrinkage height B: Average height of the convex part which is a high convex part Shrinkage Area: Area in which convex portions having a height of 10% or more of the average shrinkage height B among the convex portions existing within the range of the measurement length A are present. Shrinkage width C: total width of each shrinkage region Area ratio α (%): α = (A−C) / A × 100 (%)   The uneven | corrugated pattern formation sheet of Claim 1 whose average shrinkage height B of the high convex part of an uneven | corrugated pattern is 40% or less of the most frequent pitch P.   The uneven | corrugated pattern formation sheet of Claim 1 or 2 whose most frequent pitch P is more than 1 micrometer and 20 micrometers or less. A laminated film production step of obtaining a laminated film by providing at least one hard layer having a smooth surface on at least one surface of the heat-shrinkable resin film;
Heat shrinking step of forming a concavo-convex pattern by deforming the hard layer by folding the heat-shrinkable resin film by heating the laminated film,
The manufacturing method of the uneven | corrugated pattern formation sheet | seat characterized by including the extending process which extends | stretches the laminated | multilayer film in which the uneven | corrugated pattern was formed in the direction opposite to the shrinkage | contraction direction in a heating shrinkage | contraction process. A laminated film production step of obtaining a laminated film by providing at least one hard layer having a smooth surface on at least one surface of the heat-shrinkable resin film;
An annealing step in which the laminated film is annealed by heating at a temperature T ₁ ;
By heating the annealed laminated film at a temperature T ₂ (where T ₂ > T ₁ ) and shrinking the heat-shrinkable resin film, the hard layer is deformed so as to be folded to form an uneven pattern. A method for producing a concavo-convex pattern forming sheet, comprising: a heat shrinking step. The hard layer has a glass transition temperature Tg ₂ is the uneven pattern forming sheet according to claim 4 or 5 consisting of the heat shrinking resin film 10 ° C. or more higher than the resin above the glass transition temperature Tg ₁ of the resin constituting the Production method.   The said hard layer is a manufacturing method of the uneven | corrugated pattern formation sheet of Claim 4 or 5 which consists of a metal or a metal compound.   A duplication comprising the concavo-convex pattern-forming sheet according to claim 1 and used as a mold for producing a duplication sheet having a concavo-convex pattern having the most frequent pitch and average shrinkage height equivalent to the concavo-convex pattern-forming sheet. Process sheet master.   An optical element provided with the uneven | corrugated pattern formation sheet of Claim 1.

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