JP2016167063A - Fine concavo-convex surfaced material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine concavo-convex surfaced material, which can be used as a light distribution control sheet that satisfies both the frontal luminance and re-whitening requirements.SOLUTION: Disclosed is a fine concavo-convex surfaced material having fine protrusions and recesses formed on at least a portion of a surface thereof. When tangent lines are drawn at a predetermined interval on a height profile of a cross-section of the fine protrusions and recesses of the fine concavo-convex surfaced material in each of a Y direction, in which light passing through the surface with the fine protrusions and recesses is most widely distributed, and an X direction substantially perpendicular to the Y direction, average values of slope angles at corresponding tangent points (average slope angle Y and average slope angle X) satisfy the following expressions: (average slope angle X+average slope angle Y)/2≤4.7° ...(a), average slope angle Y≥2.4° ...(b).SELECTED DRAWING: Figure 13

Description

  The present invention relates to a surface fine uneven body, and particularly to a surface fine uneven body having a light distribution control function.

  A sheet-like surface fine uneven body, on which the uneven pattern mainly composed of fine wavy unevenness is formed, may be used as a light distribution control body such as a light distribution control sheet due to its optical characteristics. Are known.

  As a manufacturing method of a light distribution control sheet, for example, in Patent Document 1, a laminated sheet provided with a resin hard layer on a resin substrate made of a heat shrinkable film is heated to shrink the heat shrinkable film. Thus, there is disclosed a method of forming a concavo-convex pattern on the surface of a hard layer by deforming the hard layer so as to be folded into a concavo-convex shape.

Patent Document 1 describes that a concavo-convex pattern with small variation in orientation can be formed by stretching after shrinking a heat-shrinkable film. Such a sheet is preferably used as a light distribution control sheet.

JP 2011-213051 A

  In projectors and displays used in televisions, computers, mobile phones, smartphones, in-vehicle display devices, etc., a technology is used in which a white diode is used and light emitted from the white diode is collected by a condenser lens. There are many cases. In such a case, when the light emitted from the condenser lens is projected onto white paper or the like, a phenomenon in which the hue is different between the central portion and the outer peripheral portion of the projected image is observed. If there is such a difference in hue depending on the projection position, colors other than white appear on the display, and it is necessary to return this to a uniform white color. In the present specification, this is hereinafter abbreviated and referred to as “white color return”. The present inventors have found that there is a correlation between the slope angle of the light distribution control sheet and the white return when the fine surface irregularities are combined in the light collecting system as the light distribution control sheet for the white return. The method for measuring the slope angle will be described in detail later.

  Further, the characteristics of the light distribution control sheet are highly correlated with the front luminance of the projector or display.

  In the present invention, as described above, an object of the present invention is to provide a surface fine unevenness that can be used as a light distribution control sheet that can satisfy both the front luminance and the white return.

The present invention has the following aspects.
[1] A surface fine irregularity in which fine irregularities are formed on at least a part of the surface,
The height of the cross-section of the fine unevenness of the surface fine unevenness in each direction of the direction Y in which light passing through the surface on which the fine unevenness is formed is most widely distributed and the direction X substantially orthogonal to the direction Y In the profile, a fine surface irregularity body in which tangent lines are drawn at predetermined intervals, and the average value of the slope angle (average slope angle _Y and average slope angle _X ) of each contact satisfies the following formulas (a) to (b).
Average slope angle _X + average slope angle _Y ) /2≦4.7° (a)
Average slope angle _Y ≧ 2.4 ° (b)
[2] The surface fine unevenness according to [1], wherein the fine unevenness includes a wave-like uneven pattern having a plurality of protruding ridges meandering with each other and a recessed ridge between the plurality of protruding ridges.
[3] The surface fine unevenness according to [1] or [2], wherein the predetermined interval is less than 2.0 μm.

  According to the surface fine irregularities of the present invention, when used as a light distribution control body, there is an effect that can satisfy both the front luminance and the white return.

It is the optical microscope photograph which observed the fine unevenness | corrugation of the surface fine unevenness | corrugation which is an example of embodiment of this invention. It is the other laser microscope photograph which observed the fine unevenness | corrugation of the surface fine unevenness | corrugation which is an example of embodiment of this invention. FIG. 2 is an enlarged longitudinal sectional view schematically showing a portion cut along a line I-I ′ in the optical micrograph of FIG. 1. FIG. 2 is a Fourier transform image obtained by obtaining a gray scale image from the optical micrograph of the surface fine irregularities of FIG. 1 and Fourier transforming the image. It is a schematic diagram which shows typically the Fourier-transform image of FIG. 5 is a graph in which a line L1-1 is drawn so as to pass through a point having the maximum frequency in A1 from the center of FIG. 4 and a frequency distribution of the line L1-1 is plotted. FIG. 5 is a graph in which a line L1-2 is drawn from the center of FIG. 4 in a direction orthogonal to L1-1 and a frequency distribution of the line L1-2 is plotted. It is the longitudinal cross-sectional view of the principal part of the surface fine unevenness | corrugation body obtained from the observation result which observed the fine unevenness formation surface of the surface fine unevenness | corrugation body of FIG. 1 with the atomic force microscope. It is explanatory drawing of the method of calculating | requiring the average height of a convex part. It is explanatory drawing of the method of calculating | requiring the average height of a convex part.

It is a longitudinal cross-sectional view of the original plate (surface fine uneven body) for manufacturing the surface fine uneven body of FIG. It is sectional drawing explaining the manufacturing method of the original plate (surface fine unevenness | corrugation body) of FIG. (a) It is a laser microscope image of the sample of the surface fine unevenness | corrugation body (light distribution control sheet) which is an example of embodiment of this invention. (b) shows the height profile of the cross-section of the surface fine irregularities cut in the horizontal direction in the figure along the line α (parallel to the Y direction in FIG. 1) in FIG. (a) It is a figure which shows the state which pulled the tangent in each point of a 1.8 micrometer space | interval in a part of height profile of a surface fine concavo-convex body cross section. (b) is an enlarged view for explaining the inclination of the tangent line by enlarging the point U in FIG. The frequency distribution graph of the slope angle in the Y direction of the sample of the light distribution control sheet showing FWHM _Y = 20 ° and FWHM _X = 10 °. FWHM _Y = 20 °, the frequency distribution graph of the slope angle of the X-direction of the sample of the light distribution control sheet showing a FWHM _X = 10 °. The graph which shows the relationship between (average slope angle _X + average slope angle _Y ) / 2 of the sample of a light distribution control sheet, and relative front luminance. The graph which shows the relationship between the average slope angle _Y of the sample of a light distribution control sheet, and the relative white return parameter | index of a Y direction. It is a laser microscope image of the surface fine unevenness | corrugation of the sample of the light distribution control sheet of Example 2. FIG.

Hereinafter, the present invention will be described in detail.
<Surface fine irregularities>
FIG. 1 is an optical micrograph of one side of a light distribution control sheet (light distribution control body) which is an embodiment of a surface fine uneven body according to the present invention (plan view; vertical field portion of 0.4 mm length × 0.5 mm width) FIG. 2 is a laser micrograph of the fine unevenness of the light distribution control sheet of Example 1 observed with a laser microscope (“VK-8510” manufactured by Keyence Corporation). A line α in FIG. 2 indicates a height profile on a cut surface obtained by cutting the light distribution control sheet along the line β in the horizontal direction in the figure. 1 and 2 are different in magnification.

  FIG. 3 is an enlarged vertical cross-sectional view schematically showing a portion cut along a line II ′ (a line along a direction in which a convex strip portion and a concave strip portion to be described later are repeated) in the optical micrograph of FIG. FIG. FIG. 3 shows a simplified view from the viewpoint of easy understanding of the vertical cross-sectional shape of the light distribution control sheet.

  In the present specification, the “surface fine uneven body” means an article having a fine uneven structure on the surface. More specifically, “surface fine irregularities” means a secondary transfer product described later.

  As shown in FIG. 3, the light distribution control sheet 10 (surface fine irregularities) of this example is provided on a transparent base material 11 made of polyethylene terephthalate (PET) and on one surface of the base material 11. It has a two-layer structure with a transparent surface layer 12 made of a cured product of the obtained ionizing radiation curable resin, and a wavy uneven pattern 13 on the exposed side surface of the surface layer 12 and the uneven pattern The fine unevenness | corrugation comprised from many convex parts 14 formed on 13 is formed. In this example, the convex portion 14 is formed in a substantially hemispherical shape. In this example, the exposed surface of the base material 11 (the surface on the side opposite to the side on which the surface layer 12 is provided) is a smooth surface.

  The wavy uneven pattern 13 in the fine unevenness extends in the longitudinal direction in FIG. 1, and in FIG. 3, a plurality of streak-shaped protruding portions 13a extending in a direction perpendicular to the paper surface, and the plurality of protruding portions 13a. The concave ridge portions 13b are alternately repeated in one direction (lateral direction in FIGS. 1 and 2).

As shown in FIG. 3, the vertical cross-sectional shape of each ridge 13 a is a tapered shape that becomes thinner from the proximal end side toward the distal end side.

  As shown in FIG. 1, each of the plurality of ridge portions 13 a meanders and is non-parallel to each other and is irregularly formed. That is, the ridge line meanders in each protruding line part 13a, and the valley line meanders in each recessed line part 13b. Further, the interval between the ridge lines of the adjacent ridge portions 13a is not constant, and the interval between the valley lines of the adjacent ridge portions 13b is not constant.

  In the present specification, the irregularity means that when the light distribution control sheet 10 is viewed from the normal direction with respect to the base material, the ridges 13a meander and are not parallel to each other. The ridges of the strips 13a meander, the valleys of the concave strips 13b meander, and the intervals between the ridges of the adjacent convex strips 13a are not constant, and the valleys of the adjacent concave strips 13b It means that the interval is not constant.

  Moreover, the height of the ridge line is not constant in each protruding line part 13a, and the height of the valley line is not fixed in each recessed line part 13b. Therefore, as shown in FIG. 3, the vertical cross-sectional shape of each protruding item | line part 13a is different, respectively, and is not uniform but irregular.

  The fine unevenness is composed of such a wave-like uneven pattern 13 and a large number of randomly distributed convex portions 14.

  Here, the ridgeline of the “ridge 13a” means a line that connects the tops of the ridges 13a.

  When the convex part 14 exists in the middle of the ridgeline of the convex part 13a, it refers to the line drawn so that the top part of the convex part 14 may be passed.

  As the substrate 11 shown in FIG. 3, in addition to PET having excellent mechanical strength and dimensional stability, a transparent material such as resin such as polycarbonate, polymethyl methacrylate, polyethylene acrylate, and polystyrene, and glass can be used. . The thickness of the base material 11 is 30-500 micrometers, for example.

  Examples of the surface layer 12 include a cured product of a thermosetting resin, a thermoplastic resin, and the like in addition to a cured product of an ionizing radiation curable resin. Examples of the ionizing radiation curable resin include an ultraviolet curable resin and an electron beam curable resin. The thickness of the surface layer 12 should just be sufficient thickness to form the wavy uneven | corrugated pattern 13, and it is preferable that the thickness of the thickest part is about 10-25 micrometers. The thickness of the surface layer 12 means a thickness before the surface layer 12 is deformed, and can be measured using an optical non-contact film thickness measuring instrument.

  Further, in this example, the fine unevenness of the light distribution control sheet 10 is composed of a wavy uneven pattern 13 and a large number of protrusions 14. However, the fine unevenness of the surface fine unevenness of the present invention is wavy. You may be comprised from the uneven | corrugated pattern and many recessed parts.

  In the light distribution control sheet 10, the repeating direction (horizontal direction in FIG. 1) of the wavy uneven pattern 13 is referred to as direction Y, and the direction orthogonal to the direction Y (vertical direction in FIG. 1) is referred to as direction X.

  In this specification, in this XY orthogonal coordinate system, the first direction is referred to as the Y-axis direction, and the second direction is referred to as the X-axis direction. In addition, the direction orthogonal to the XY axis may be referred to as the third direction or the normal direction of the substrate of the surface fine unevenness.

  In the illustrated light distribution control sheet 10, the most frequent pitch of the wavy uneven pattern 13 is set to 5 to 50 μm from the viewpoint of exhibiting light distribution control performance. The most frequent pitch of the wavy uneven pattern 13 is preferably 10 to 40 μm, more preferably 15 to 30 μm. The pitch is the distance between the tops of adjacent ridges.

  When the most frequent pitch is within the above range, a surface on which fine irregularities are formed (hereinafter sometimes referred to as a fine irregularity forming surface) or a smooth surface side opposite to the surface with respect to the light distribution control sheet 10 When the light is incident from the side, the outgoing light from the surface opposite to the incident surface is well distributed in the direction Y (wide light distribution direction).

  And the fine unevenness | corrugation of the light distribution control sheet 10 of the example of illustration has many convex parts formed in addition to the wavy uneven | corrugated pattern 13 mainly responsible for the light distribution in the wide light distribution direction as mentioned above. 14. Therefore, the anisotropy of the wavy uneven pattern 13 is moderately weakened by the protrusions 14. As a result, when light is incident on the light distribution control sheet 10 from one of the surfaces, the emitted light from the opposite surface is also distributed in the direction X (the direction orthogonal to the wide light distribution direction). Light and smaller than direction Y.

  The apparent mode diameter of the convex portion 14 is preferably 1 to 10 μm, more preferably 3 to 6 μm, and still more preferably 4 to 5 μm. Here, the reason for describing “apparent” is that these mode diameters are, for example, in FIG. 3, the diameter of the light distribution control sheet 10 observed from above (the normal direction of the base material) as a micrograph. It is because it sees as.

    FWHM in this specification can be measured by the following method using a light distribution characteristic measuring apparatus (for example, GENESISIA GonioFar Field Profiler (manufactured by Genesia)).

First, light is irradiated and incident on the light distribution control sheet 10 from the smooth surface side opposite to the fine unevenness forming surface. At this time, the illuminance of the outgoing light (light outgoing angle = 0 °) emitted perpendicularly from the side opposite to the incident surface is used as the reference value, and the outgoing light within the range of the light outgoing angle along the direction Y of −90 ° to + 90 °. Is measured as a relative value with respect to the reference value, for example, every 1 °. The illuminance curve is obtained by plotting the illuminance value with respect to the light emission angle in each direction Y.

The full width at half maximum (full width at half maximum) in the illuminance curve is referred to as FWHM in the wide light distribution direction (direction Y). Further, the illuminance of the outgoing light within the range of the outgoing light angle of −90 ° to + 90 ° along the direction X is measured as a relative value with respect to the reference value, for example, every 1 °. Then, the illuminance value is obtained by plotting the illuminance value with respect to the light emission angle in each direction X. The full width at half maximum (full width at half maximum) in the illuminance curve is defined as FWHM in a direction (direction X) orthogonal to the wide light distribution direction. In this specification, when the above direction is illustrated, the FWHM for the X direction is displayed as “FWHM _X”, and the FWHM for the Y direction is displayed as “FWHM _Y” .

  In the present specification, the mode pitch of the wavy uneven pattern 13 and the apparent mode diameter of the convex portion 14 are measured and defined as follows.

  First, an optical micrograph as shown in FIG. 1 is obtained for the fine surface irregularities. The observation visual field in that case shall be 0.4-1.6 mm long and 0.5-2 mm wide. If this image is a compressed image such as jpeg, it is converted into a grayscale Tif image. Then, Fourier transform is performed to obtain a Fourier transform image as shown in FIG.

  Moreover, the schematic diagram of the Fourier-transform image of FIG. 4 is shown as FIG.

  Here, the white portions denoted by reference signs A1 and A2 in FIG. 4 include information on the pitch of the wavy uneven pattern since the shape thereof has directionality. White brightness indicates frequency (except for the center point). On the other hand, the white circular ring B in FIG. 4 includes information on the diameters of a large number of convex portions because the shape thereof has no directionality.

  Therefore, when the line L1-1 is drawn from the center of FIG. 4 so as to pass the point having the maximum frequency in A1, and the frequency distribution of the line L1-1 is plotted, the graph of FIG. 6 is obtained.

  Further, when a line L1-2 is drawn from the center of FIG. 4 in a direction perpendicular to L1-1 and the frequency distribution of the line L1-2 is plotted, the graph of FIG. 7 is obtained.

  In FIG. 6, 1 / XA having a high frequency is the most frequent pitch of the wavy uneven pattern in the light distribution control sheet 10.

  In FIGS. 6 and 7, 1 / XB and 1 / YB, which are frequently used, are the mode diameters in the L1-1 direction and the L1-2 direction, respectively, of the large number of convex portions in the light distribution control sheet 10. That is, 1 / XA is the most frequent pitch of the wavy uneven pattern, and) (1 / XB + 1 / XB) / 2 is the apparent most frequent diameter of a large number of convex portions.

  In the Fourier transform image of FIG. 4, the orientation from the center means the direction of the periodic structure (uneven pattern 13) existing in FIG. 1, and the distance from the center is the period of the periodic structure existing in FIG. Means the reciprocal. In this example, as shown in FIG. 1, since the wavy uneven pattern 13 is repeated in the horizontal direction in the figure, the most frequent pitch in the line L <b> 1-1 extending in the horizontal direction in the figure from the center in the Fourier transform image. The luminance (frequency) of the portion corresponding to the reciprocal of is high.

  In FIG. 5, XB is a position where the frequency is maximum in a portion passing through the ring of the line L <b> 1-1 (not shown in FIG. 5). In FIG. 5, YB is the line L <b> 1-2. It is a position where the frequency is maximum in a portion passing through the circular ring (not shown in FIG. 5).

  At least five optical micrographs as shown in the figure are taken, and the average value of the mode pitches obtained as described above for each photo is defined as the “mode pitch” of the wavy uneven pattern 13. That is, the “most frequent pitch” refers to the distance between the tops having the highest appearance frequency among the distances between the tops of the adjacent ridges. Further, the average value of the apparent mode diameter obtained as described above for each photograph is defined as the “apparent mode diameter” of the convex portion 14. That is, the “apparent mode diameter” refers to a diameter having the highest appearance frequency among the diameters of the convex portions formed on the concave / convex pattern.

  The fine irregularities of the surface fine irregularities may have concave portions instead of convex portions, and the “apparent mode diameter” of the concave portions is the same as the “apparent mode diameter” of the convex portions. Desired. That is, in other words, the apparent mode diameter means that a Fourier transform image is obtained from an optical micrograph of the surface on which fine irregularities are formed, and the diameters in two orthogonal directions of a large number of concave portions or convex portions are obtained from the Fourier transform image. Is the average value of the most frequent diameters of a large number of concave portions or convex portions obtained based on the frequency distribution.

  As for the average height of the protruding item | line part 13a which comprises the wavy uneven | corrugated pattern 13, 0.3-10 micrometers is preferable, More preferably, it is 0.5-5 micrometers, More preferably, it is 1-3 micrometers. Light distribution control performance is sufficiently obtained when the average height of the ridges 13a is in the above range.

  In the present specification, the average height of the ridges 13a of the wavy uneven pattern 13 is measured and defined as follows.

  First, the surface having fine irregularities formed on the light distribution control sheet 10 is observed with an atomic force microscope, and from the observation result, the longitudinal sectional view as shown in FIG. Get. And the height H of the said protruding item | line part 13 is calculated | required from sectional drawing of the protruding item | line part 13a of the part in which the protruding part 14 does not exist. Specifically, the height H of the ridge portion 13a is set to H1 as a vertical distance between the top portion T of the ridge portion 13a and the bottom portion B1 of the ridge portion 13b located on one side of the ridge portion 13a. When the vertical distance between the top portion T of the ridge portion 13a and the bottom portion B2 of the ridge portion 13b located on the other side of the ridge portion 13a is defined as H2, H = (H1 + H2) / 2.

  Such measurement is performed on 50 portions of the ridge portion 13a where the ridge portion 14 does not exist, and the average value of the 50 data is defined as “average height of the ridge portion”.

  On the other hand, the average height of the convex portion 14 is preferably 0.5 to 3 μm, more preferably 1 to 2 μm, and still more preferably 1.1 to 1.5 μm. When the average height of the protrusions 14 is within the above range, the anisotropy of the wavy uneven pattern 13 can be moderately weakened.

  In this specification, the average height of the convex part 14 is measured and defined as follows.

First, the cross-sectional view of FIG. 8 is obtained as described above. Then, as shown in FIG. 9, the waveform is separated into a shape derived from the wavy uneven pattern 13 and a shape derived from the convex portion 14. The waveform separation is performed using a shape derived from the wavy uneven pattern 13 as a sine curve. Next, the shape derived from the wavy uneven pattern 13 is subtracted from the cross-sectional view of FIG. 9 to obtain a cross-sectional view of only the shape derived from the convex portion 14 as shown in FIG. Then, in the cross-sectional view of FIG. 10, the height H ′ of the convex portion 14 is obtained as H ′ = (H1 ′ + H2 ′) / 2. In the cross-sectional view of FIG. 10, H1 ′ is a vertical distance between the top portion T ′ of the convex portion 14 and the base line L _α on one side of the convex portion 14, and H2 ′ is the top portion T ′ of the convex portion 14. it is a vertical distance between the baseline L _beta of the other side of the convex portion 14.

  Such measurement is performed on 50 convex portions 14, and the average value of 50 data is defined as "average height of convex portions".

  30 to 70% is preferable, as for the occupation area ratio of the convex part 14 in the fine unevenness | corrugation of the light distribution control sheet 10, More preferably, it is 40 to 60%, More preferably, it is 45 to 55%. When the occupation area ratio of the convex portions 14 is within the above range, the anisotropy of the wavy uneven pattern 13 can be moderately weakened.

  In this specification, the occupation area ratio γ (%) of the convex portion 14 in the light distribution control sheet 10 is measured and defined as follows.

First, an optical micrograph as shown in FIG. 1A is obtained, and the number n of convex portions 14 recognized in the area S2 of the entire visual field (for example, 0.4 to 1.6 mm in length and 0.5 to 2 mm in width). And the area S1 = nr ² π occupied by the n convex portions 14 in the entire field of view is obtained. The occupied area ratio γ (%) is obtained by the following formula.

  γ (%) = S1 × 100 / S2 (where r is a half of the apparent mode diameter of the convex portion (ie, radius))

  As described above, the light distribution control sheet 10 in the illustrated example is formed on one surface of the specific wavy uneven pattern 13 mainly responsible for light distribution in the direction Y, and the wavy uneven pattern 13. The concavo-convex pattern 13 has fine concavo-convex mainly composed of a large number of convex portions 14 that moderately weaken the anisotropy and increase the light distribution in the direction X.

  Further, the ridges 13a constituting the wavy uneven pattern 13 of the light distribution control sheet 10 in the illustrated example are non-parallel to each other and meandering, and have no regularity. Therefore, the anisotropy of the concavo-convex pattern 13 is moderately weakened, and it is considered that the effect of increasing the FWHM in the direction X appears more remarkably together with the effect of the convex portion 14 being formed. .

  As a method of expanding the FWHM in the direction X, a method of adding high refractive index particles or the like is also conceivable.

  However, the addition of high refractive index particles or the like tends to lower the light transmittance of the light distribution control sheet. On the other hand, in the method of increasing the FWHM in the direction X by specifically controlling fine irregularities as in the present invention, it is not necessary to add high refractive index particles or the like, and even when added, the addition The amount can be small. Therefore, the light transmittance can be maintained high.

  The illustrated light distribution control sheet 10 includes, for example, a light distribution control member for a projector; backlight light distribution control for a television, a monitor, a notebook personal computer, a tablet personal computer, a smartphone, a mobile phone, and the like. It is also suitably used as a member.

  The light distribution control sheet 10 is also preferably used as a light distribution control member that constitutes the exit surface of the light guide member in a scanner light source in which LED light sources are arranged in a line, used in a copying machine or the like. The

  One aspect of the present invention is the use of the above-described surface fine unevenness as a light distribution control sheet or a light distribution control member, or a method of using the same. In addition, when the fine surface irregularities of the present invention are used as a light distribution control sheet or a light distribution control member, the application destination thereof is as described above for projectors, backlights for personal computers, mobile phones, etc. Examples include a light distribution control member such as an emission surface of the optical member.

<Method for producing surface fine unevenness>
The light distribution control sheet 10 (surface fine uneven body) in the illustrated example uses a light distribution control sheet forming original plate (light distribution control body forming original plate) having fine unevenness on the surface as a mold. It can be produced by a method having a transfer step of transferring fine irregularities of an original plate (hereinafter also referred to as “original plate”).

  One aspect of the present invention is the use of the surface fine concavo-convex body as a light distribution control sheet or an original plate for producing a light distribution control member.

  The light distribution control sheet 10 in the illustrated example is a secondary transfer product obtained by transferring the fine irregularities of the original plate to obtain a primary transfer product, and then further transferring the fine irregularities of the primary transfer product. The fine unevenness of the primary transfer product is a reverse pattern of the fine unevenness of the original plate, but the fine unevenness of the secondary transfer product is the same pattern as the fine unevenness of the original plate. Therefore, in this example, a surface fine uneven body having the same fine unevenness as the light distribution control sheet 10 in the illustrated example is manufactured as an original plate, and this is used as a transfer mold to perform secondary transfer, and the light distribution control sheet 10 in the illustrated example. Is manufacturing.

  Further, in the n-order transfer product, when n is an even number, the fine unevenness of the transfer product is the same pattern as the fine unevenness of the original plate, but when n is an odd number, the transfer product has The fine unevenness becomes a reversal pattern of the fine unevenness of the original. And, when n is an n-order transfer product having an odd number and the fine unevenness of the original used for transfer has a convex part, the fine unevenness of the n-order transfer product (n is an odd number) The convex part has a concave part that is inverted. As already described, the fine irregularities of the surface fine irregularities of the present invention may be in the form of having concave portions instead of convex portions. Therefore, the surface fine irregularities of the present invention include not only the above-mentioned original plate and the original n-order transfer product (n is an even number) but also the original n-order transfer product (n is an odd number).

  Hereinafter, a manufacturing method of the light distribution control sheet 10 of the illustrated example which is a secondary transfer product will be described.

[Original version]
In manufacturing the light distribution control sheet 10 of the illustrated example, first, the surface fine uneven body 20 shown in FIG. 11 is manufactured and used as an original. The original plate has a base material 21 made of a resin and a hard layer 22 provided on the entire one surface of the base material 21, and the exposed surface of the hard layer 22 has a light distribution control in the illustrated example. It is formed in the same fine irregularities as the sheet 10.

  In this example, the hard layer 22 includes a matrix resin 22a and particles 22b dispersed in the matrix resin 22a. The hard layer 22 is deformed so as to be folded, and the thickness t of the hard layer 22 (part where no particles exist). Is set smaller than the particle diameter d of the particles. Therefore, the hard layer 22 has a wavy uneven pattern 13 ′ (projection strip portion 13 a ′ and recess strip portion 13 b ′) formed by being deformed as folded, and each particle 22 b dispersed in the hard layer 22. Has a fine asperity composed of a protrusion 14 ′ formed by protruding toward the surface side of the hard layer 22. The contact surface of the base material 21 with the hard layer 22 has a concavo-convex shape following the shape of the hard layer 22 deformed as if folded.

  Note that the thickness t of the hard layer 22 is a portion of the hard layer 22 where the particles 22b are not present from a micrograph of a cross section (longitudinal cross section) obtained by cutting the surface fine irregularities 20 perpendicular to the surface direction. This is the average value of the numerical values obtained when randomly extracting more than one point and measuring the thickness of each part in the normal direction.

  The particle diameter d of the particles 22b is a mode diameter (mode) measured by a laser diffraction / scattering particle size distribution analyzer for particles that are uniformly monodispersed.

  As described in detail later, the surface fine concavo-convex body 20 of FIG. 11 forms a laminated sheet by providing a hard layer in which particles are dispersed in a matrix resin on one side of a base film made of resin. It can be manufactured by a method having a laminating step and a deforming step of deforming at least a hard layer of the laminated sheet so as to be folded. According to this method, it is possible to form meandering portions 13 a ′ which meander each other and are not parallel to each other and irregular. Further, the vertical cross section of each protruding line portion 13a 'is tapered from the proximal end side toward the distal end side.

  1, the glass transition temperature Tg2 of the matrix resin 22a needs to be 10 ° C. or more higher than the glass transition temperature Tg1 (° C.) of the resin constituting the substrate 21. Further, the particles 22b need to be mainly composed of a material whose particle shape is not changed by heat at a temperature lower than a temperature 10 ° C. higher than the glass transition temperature of the resin constituting the substrate 21. In other words, at a temperature Tx satisfying the relationship of Tx <Tg1 + 10, it is necessary to be mainly composed of a material whose particle shape does not change due to heat.

  Here, “the particle shape does not change” means that the particle shape and particle diameter do not change before and after heating.

  That is, the resin constituting the base material 21 and the matrix resin 22a need to be selected so that the difference between these glass transition temperatures (Tg2−Tg1) is 10 ° C. or more. 20 degreeC or more is preferable and 30 degreeC or more is more preferable. When (Tg2−Tg1) is 10 ° C. or more, it is easy at a temperature between Tg2 and Tg1 (that is, at a processing temperature satisfying the relationship of Tg1 <Tx <Tg2 when the processing temperature is Tx (° C.)). In addition, processing such as heat shrinkage can be performed in the deformation process described later. Further, if the temperature between Tg2 and Tg1 is the processing temperature Tx (that is, the processing temperature satisfies the relationship of Tg1 <Tx <Tg2), the base material has a Young's modulus higher than the Young's modulus of the matrix resin 22a. As a result, the corrugated uneven pattern 13 ′ can be easily formed on the hard layer 22 in the deformation process described later. The processing temperature is a temperature at which the hard layer 22 is deformed so as to be folded at least in the deformation process (for example, a heating temperature at the time of thermal contraction).

  Further, the necessity of using a resin having a Tg2 exceeding 400 ° C. is scarce from an economic viewpoint, and there is no resin having a Tg1 lower than −150 ° C. Therefore, (Tg2−Tg1) is preferably 550 ° C. or less. More preferably, it is 200 ° C. or lower. That is, in one embodiment of the present invention, (Tg2-Tg1) is preferably 10 to 550 ° C, more preferably 30 to 200 ° C. Note that the difference in Young's modulus between the base material 21 and the matrix resin 22a at the processing temperature in the deformation process described later is preferably 0.01 to 300 GPa because the wavy uneven pattern 13 ′ can be easily formed. More preferably, it is 1-10 GPa.

  The Young's modulus is a value measured according to JIS K 7113-1995.

  Tg1 is preferably −150 to 300 ° C., more preferably −120 to 200 ° C. There is no resin having a Tg1 lower than −150 ° C., and if the Tg1 is 300 ° C. or lower, the temperature can be easily raised and heated to the above processing temperature.

  The Young's modulus of the resin constituting the base material 21 at the above processing temperature is preferably 0.01 to 100 MPa, and more preferably 0.1 to 10 MPa. If the Young's modulus of the resin constituting the base material 21 is 0.01 MPa or more, it is a hardness that can be used as the base material, and if it is 100 MPa or less, the hard layer 22 is deformed following the deformation at the same time. It is possible softness.

  As the material constituting the particles 22b, at least one kind of material whose particle shape does not change by heat can be used at a temperature lower than 10 ° C. higher than the glass transition temperature of the resin constituting the substrate 21. In other words, at a temperature Tx that satisfies the relationship of Tx <Tg1 + 10, one or more materials that do not change the particle shape due to heat can be used.

  For example, when the material constituting the particles 22b is at least one selected from the group consisting of a resin having a glass transition temperature and an inorganic material having a glass transition temperature, the glass transition temperature Tg3 is the glass transition temperature of the matrix resin. It is necessary to satisfy the same conditions as Tg2, that is, (Tg3-Tg1) should be selected to be 10 ° C. or higher, and (Tg3-Tg1) is more preferably 20 ° C. or higher, and 30 ° C. or higher. Further preferred. When (Tg3−Tg1) is 10 ° C. or higher, the convex portion 14 ′ is surely formed without the particles 22 b being deformed and melted at the above processing temperature.

  When the material constituting the particles 22b is a material that does not have a glass transition temperature, such as an internally cross-linked resin, the Vicat softening temperature (as defined in JIS K7206) satisfies the above-described condition, that is, It is preferably higher than the glass transition temperature of the resin constituting the base material 21 by 10 ° C. or higher, preferably higher by 20 ° C., more preferably higher by 30 ° C. or higher.

  In addition, in this specification, description, such as a preferable temperature range about glass transition temperature Tg3, when the particle 22b does not have a glass transition temperature and is mainly composed of a material having a Vicat softening temperature, the Vicat softening temperature. It shall be applicable.

  Further, as the material constituting the particles 22b, even if the glass transition temperature and the Vicat softening temperature cannot be measured, the particles are heated by heat at a temperature lower than 10 ° C. higher than the glass transition temperature Tg1 of the resin constituting the base material 21. Any material that does not change shape can be used in the present invention. In other words, at a temperature Tx that satisfies the relationship of Tx <Tg1 + 10, any material that does not change its particle shape due to heat can be used in the present invention.

  Tg2 and Tg3 are preferably 40 to 400 ° C, and more preferably 80 to 250 ° C. If Tg2 and Tg3 are 40 ° C. or higher, the above-mentioned processing temperature can be increased to room temperature or higher, which is useful, and matrix resin 22a or Tg3 having Tg2 higher than 400 ° C. is higher than 400 ° C. Use of the particles 22b is less necessary from the viewpoint of economy.

  The Young's modulus of the matrix resin 22a at the above processing temperature is preferably 0.01 to 300 GPa, and more preferably 0.1 to 10 GPa. If the Young's modulus of the matrix resin 22a is 0.01 GPa or more, sufficient hardness is obtained from the Young's modulus at the processing temperature of the resin constituting the substrate 21, and after the wavy uneven pattern 13 'is formed, The hardness is sufficient to maintain the uneven pattern 13 ′. Use of a resin having a Young's modulus exceeding 300 GPa as the matrix resin 22a is less necessary from the viewpoint of economy.

  Examples of the resin constituting the substrate 21 include polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, polystyrene resins such as styrene-butadiene block copolymers, polyvinyl chloride, polyvinylidene chloride, and polydimethylsiloxane. Examples thereof include resins such as silicone resin, fluororesin, ABS resin, polyamide, acrylic resin, polycarbonate, and polycycloolefin.

  Among these, polyester and polycarbonate are preferable because a desired uneven shape can be easily obtained after shrinkage.

  The resin preferably has a mass average molecular weight of 1,000 to 1,000,000. 10,000 to 100,000 are more preferable. The mass average molecular weight refers to a value measured using gel permeation chromatography. As specific measurement conditions, as the eluent, one appropriately selected from tetrahydrofuran, chloroform, hexafluoroisopropanol and the like can be used. Further, as the molecular weight standard substance, a material appropriately selected from known molecular weight polystyrene, polymethyl methacrylate and the like can be used. Moreover, as measurement temperature, it can select suitably in the range of 35-50 degreeC.

The matrix resin 22a is selected according to the type of the base material 21 so that the glass transition temperature Tg2 satisfies the above-mentioned conditions. For example, polyvinyl alcohol, polystyrene, acrylic resin, styrene-acrylic copolymer, styrene -Acrylonitrile copolymer, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethersulfone, fluororesin, etc. can be used.
Among these, acrylic resins are preferable in terms of transparency.

  The matrix resin preferably has a mass average molecular weight of 1,000 to 10,000,000, more preferably 10,000 to 2,000,000. The mass average molecular weight refers to a value measured using gel permeation chromatography. As specific measurement conditions, as the eluent, one appropriately selected from tetrahydrofuran, chloroform, hexafluoroisopropanol and the like can be used. Further, as the molecular weight standard substance, a material appropriately selected from known molecular weight polystyrene, polymethyl methacrylate and the like can be used. Moreover, as measurement temperature, it can select suitably in the range of 35-50 degreeC.

  The matrix resin 22a may be used alone, but may be appropriately used in accordance with the purpose of adjusting the mode pitch, average height, and orientation degree of the wavy uneven pattern. For example, resins of the same type but different in glass transition temperature can be used in combination, or different types of resins can be used in combination.

  The resin constituting the particles 22b is selected according to the type of the base material 21 so that the glass transition temperature Tg3 (or Vicat softening point) satisfies the above-described conditions, for example, acrylic thermoplastic resin particles, Examples thereof include polystyrene-based thermoplastic resin particles, acrylic-based crosslinked resin particles, and polystyrene-based crosslinked resin particles. Examples of the inorganic material include glass beads.

  The thickness of the substrate 21 is preferably 30 to 500 μm. If the thickness of the base material is 30 μm or more, the manufactured original plate is hardly broken, and if the thickness is 500 μm or less, the original plate can be easily thinned. In addition, the thickness of the base material 21 is randomly extracted from a microphotograph of a cross section (longitudinal section) obtained by cutting the surface fine irregularities (original plate) 20 of FIG. It is an average value of the obtained numerical values when the thickness of the substrate 21 is measured.

  Moreover, in order to support the base material 21, you may provide separately the resin-made support bodies of thickness 5-500 micrometers.

  The thickness t of the hard layer 22 is preferably more than 0.1 μm and 10 μm or less, and more preferably 0.3 to 5 μm. If the thickness t of the hard layer 22 is more than 0.1 μm and not more than 10 μm, a wavy uneven pattern 13 ′ suitable as a light distribution control body can be formed. Moreover, you may form a primer layer between the base material 21 and the hard layer 22 for the purpose of improving adhesiveness or forming a finer structure.

  The particle diameter d of the particles 22b needs to be larger than the thickness t of the hard layer 22, and is set according to the thickness t of the hard layer 22. In addition, the apparent mode diameter of the convex portion 14 of the light distribution control sheet 10 of the illustrated example manufactured using the surface fine uneven body 20 of FIG. 11 as an original plate is appropriately set so that the apparent mode diameter is within the above-described preferable range. Is done. The preferable particle diameter d is, for example, 5 to 15 μm, and more preferably 5 to 8 μm.

  In addition, the surface fine unevenness | corrugation body 20 of FIG. 11 can also be used as a light distribution control body instead of an original plate. In that case, a transparent material is used for the material used for the base material 21, the matrix resin 22 a, and the particles 22 b so that the surface fine uneven body 20 sufficiently functions as a light distribution control body.

[Original plate manufacturing method]
11 is dispersed in the matrix resin and the matrix resin on one surface (flat surface) of the laminated film 30 as shown in FIG. 12, that is, the base film 31 made of resin. A laminating step of forming a laminated sheet 30 provided with a hard layer 32 having a thickness of more than 0.1 μm and not more than 10 μm, and a deformation step of deforming at least the hard layer 32 of the laminated sheet 30 so as to be folded. It can be manufactured by the method of having. Here, the substrate film 31 corresponds to the substrate 21 of the surface fine irregularities 20 of FIG. Here, the term “flat” refers to a surface having a center line average roughness of 0.1 μm or less as described in JIS B0601.

(Lamination process)
In the laminating step, first, a coating liquid (dispersion or solution) containing matrix resin 22a, particles 22b, and a solvent is prepared, and the coating liquid is applied to one surface of the base film 31 by a spin coater or a bar coater. As shown in FIG. 12, the hard layer 32 having a thickness t ′ exceeding 0.1 μm and not more than 10 μm is formed. The hard layer 32 at this time is not deformed so as to be folded.

  Instead of providing the coating liquid directly on the base film 31 as described above, the hard layer 32 is obtained by laminating a hard layer (a film in which particles are dispersed in a matrix resin) prepared in advance on the base film. You may provide by the method to do.

  The base film 31 is preferably a uniaxial heat shrinkable film made of resin. When the uniaxial heat-shrinkable film is used, by heating the laminated sheet 30 in the next deformation step, the hard layer 32 can be easily deformed so as to be folded and the wavy uneven pattern 13 ′ can be formed. Further, according to this method, it is possible to form irregular ridges 13a 'that meander each other and are not parallel to each other.

  The resin constituting the uniaxial heat-shrinkable film is as already exemplified as the resin constituting the base material 21. Specifically, a shrink film such as a polyethylene terephthalate shrink film, a polystyrene shrink film, a polyolefin shrink film, or a polyvinyl chloride shrink film can be preferably used.

  Among these shrink films, those shrinking 20 to 70% in the uniaxial direction are preferable. If a shrink film that shrinks by 20 to 70% is used, the deformation ratio can be increased to 20% or more, and as a result, a wavy uneven pattern 13 'having a suitable mode pitch and the height of the protruding portion 13a' can be formed.

  Here, the deformation rate is (length before deformation−length after deformation) × 100 / (length before deformation) (%). Alternatively, (deformed length) × 100 / (length before deformation) (%).

  Further, when a uniaxial heat-shrinkable film is used as the base film 31 as described above and this is heat-shrinked in the next deformation step, the uneven pattern 13 ′ can be formed more easily. The rate is preferably 0.01 to 300 GPa, more preferably 0.1 to 10 GPa.

  As the resins constituting the matrix resin 22a and the particles 22b used in the coating liquid, those already exemplified can be used. The glass transition temperature Tg2 of the matrix resin 22a and the glass transition temperature Tg3 of the particles 22b are the base materials. It is important to select and combine the materials so that the glass transition temperature Tg1 of the film 31 is 10 ° C. or higher. Thus, after selecting each material, the laminated sheet 30 which provided the hard layer 32 whose thickness t 'exceeds 0.1 micrometer and is 10 micrometers or less on the single side | surface of the uniaxial heat-shrinkable film (base film 31). When it is used, a wavy uneven pattern 13 ′ in which the most frequent pitch is 5 to 50 μm and the average height of the ridges 13a ′ is 0.3 to 10 μm is easily formed through the following deformation process.

  Although it does not specifically limit as a solvent used for a coating liquid, It depends also on the kind of matrix resin 22a. When the matrix resin 22a is, for example, an acrylic resin, one or more of toluene, methyl ethyl ketone, methyl isobutyl ketone, acetone, ethyl acetate, and the like can be preferably used.

  The concentration of the matrix resin 22a in the coating solution is preferably 5 to 10% by mass as a net amount (solid content) from the viewpoint of coating properties. Moreover, it is preferable that it is 10-50 mass parts with respect to 100 mass parts of net amounts of the matrix resin 22a, and, as for the quantity of the particle | grains 22b, it is more preferable that it is 20-30 mass parts. Within such a range, the occupation area ratio of the convex portion 14a 'or the concave portion in the fine irregularities to be formed can be controlled within the above-mentioned preferable range.

  Here, the net amount (solid content) refers to the ratio of the mass of the solid content remaining after the solvent in the coating solution volatilizes with respect to the mass (100 mass%) of the coating solution.

  Note that the thickness t ′ of the hard layer 32 formed in the laminating step may be continuously changed as long as it is in the range of more than 0.1 μm and not more than 10 μm. In that case, the pitch and depth of the concavo-convex pattern formed by the deformation process are continuously changed. The thickness t ′ of the hard layer 32 hardly changes even after the next deformation step, and can be considered as t ′ = t.

(Deformation process)
11 is obtained by heating the laminated sheet 30 obtained as described above and causing the base film 31 of the laminated sheet 30 to be thermally contracted. In addition, as a deformation | transformation process, the well-known method disclosed by the Japan patent 4683011 etc. is employable, for example. Further, in the present invention, after heat shrinkage, the laminated sheet 30 is stretched in two directions including the same direction substantially parallel to the axial direction of the uniaxial heat-shrinkable film or a direction substantially perpendicular thereto, and unevenness with small orientation variation. More preferably, a pattern is formed.

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

  The heating temperature (processing temperature) Tx when the base film 31 is thermally shrunk is preferably a temperature between Tg2 and Tg1 (that is, Tg1 <Tx <Tg2). It is preferable to select appropriately according to the type of the film 31 and the pitch of the intended uneven pattern 13 ′, the height of the ridge 13a ′, and the like.

  Examples of the stretching method include a method of pulling and stretching one end portion of the laminated sheet and the opposite end portion. The heating temperature (processing temperature) at the time of stretching is preferably the same as the temperature at the time of shrinkage, and specifically, it is preferable to select appropriately according to the intended stretching ratio.

  In this manufacturing method, the thinner the thickness of the hard layer 22 and the lower the Young's modulus of the hard layer 22, the smaller the most frequent pitch of the uneven pattern 13 ′ and the higher the deformation rate of the base film 31. The height of the ridge portion 13a ′ increases as the height increases. Therefore, in order to set the most frequent pitch of the concavo-convex pattern 13 ′ and the height of the ridge 13 a ′ to desired values, it is necessary to appropriately select the above conditions.

In addition, the surface fine unevenness | corrugation body 20 of a structure like FIG. 11 can also be manufactured by the method of following (1)-(4).
(1) A method of forming a laminated sheet by providing an undeformed hard layer on one side of a flat base film, and compressing the whole laminated sheet in one direction along the surface.

When the glass transition temperature of the base film is lower than room temperature, the laminated sheet is compressed at room temperature. When the glass transition temperature of the base film is higher than the room temperature, the laminated sheet is compressed above the glass transition temperature of the base material and hard. Performed below the glass transition temperature of the layer.
(2) An undeformed hard layer is provided on one side of a flat base film to form a laminated sheet, the laminated sheet is stretched in one direction, and the direction perpendicular to the stretching direction is shrunk to form a hard layer. A method of compressing in one direction along the surface.

When the glass transition temperature of the base film is lower than room temperature, the lamination sheet is stretched at room temperature. When the glass transition temperature of the base film is room temperature or higher, the stretching of the laminated sheet is equal to or higher than the glass transition temperature of the base film. It is performed below the glass transition temperature of the hard layer.
(3) A flat base film formed of an uncured ionizing radiation curable resin is laminated with an undeformed hard layer to form a laminated sheet, and the base film is cured by irradiation with ionizing radiation. A method of compressing the hard layer laminated on the base film in at least one direction along the surface.
(4) An undeformed hard layer is laminated on a flat base film swelled by swelling a solvent to form a laminated sheet, and the solvent in the base film is dried and contracted by removing it. The method of compressing the hard layer laminated | stacked on the base film in at least one direction along the surface.

  In the method of (1), as a method of forming a laminated sheet, for example, a resin solution or dispersion containing particles is applied to one side of a flat base film using a spin coater or bar coater, and a solvent is used. Examples thereof include a drying method and a method in which a hard layer prepared in advance is laminated on one side of a flat base film. Examples of the method for compressing the entire laminated sheet in one direction along the surface include a method of compressing the laminated sheet by sandwiching one end portion of the laminated sheet and the opposite end portion thereof with a vise or the like.

  In the method (2), examples of the method of stretching the laminated sheet in one direction include a method of stretching by stretching one end portion of the laminated sheet and the opposite end portion thereof.

  In the method (3), examples of the ionizing radiation curable resin include an ultraviolet curable resin and an electron beam curable resin.

  In the method (4), the solvent is appropriately selected according to the type of resin constituting the base film. The drying temperature of the solvent is appropriately selected according to the type of solvent.

  In the hard layer in the methods (2) to (4), the same components as those used in the method (1) can be used, and the thickness can be the same. Moreover, the formation method of a lamination sheet is the same as the method of (1), the method of apply | coating a coating liquid on the single side | surface of a base film, and drying the solvent, The hard layer produced beforehand on the single side | surface of a base film The method of laminating can be applied.

  Moreover, you may manufacture the original of a surface fine unevenness | corrugation using a biaxial direction heat shrinkable film instead of a uniaxial direction heat shrinkable film. If a biaxial heat-shrinkable film is used instead of the uniaxial heat-shrinkable film used in the laminating process described above, it can be produced in the same manner in terms of process. The concavo-convex pattern of the surface fine concavo-convex body obtained using the biaxial heat-shrinkable film is a concavo-convex pattern that does not follow a specific direction. When a biaxial heat-shrinkable film is used, the obtained surface fine unevenness is obtained by using a direction X substantially orthogonal to the direction Y in which light passing through the surface on which the surface fine unevenness is formed is most widely distributed. In addition, since it has a certain amount of FWHM, it is not always necessary to add particles (reference: particles 22b in FIG. 11) to the hard layer. In the case where particles are not added in this way, in the laminating step described above, if a coating liquid not containing particles (22b) is used, it can be produced in the same manner in terms of steps. Using the biaxial heat-shrinkable film as described above, the original plate manufacturing method of the surface fine irregularities without adding particles is simply abbreviated as “biaxial heat-shrinkable film and particle-free manufacturing method”. Say. In addition, even when this biaxial heat-shrinkable film and a production method without addition of particles are used, after heat shrinking, the laminated sheet 30 is stretched in the same direction substantially parallel to the axial direction of the biaxial heat-shrinkable film. It is preferable to do. This stretching direction may be substantially the same as one of the biaxial directions, or may be both biaxial directions. It is more preferable to form a concavo-convex pattern with a small variation in orientation by appropriately combining these axial shrinkage and the draw ratio. Even when a uniaxial heat-shrinkable film is used, a desired concavo-convex pattern can be formed by appropriately combining the shrinkage rate and the draw ratio, and it is not always necessary to add particles to the hard layer.

[Manufacturing method of surface irregularities by transfer using original plate]
When manufacturing the light distribution control sheet 10 in the illustrated example using the surface fine irregularities 20 of FIG. 11 as an original, a transfer step of transferring the fine irregularities of the surface fine irregularities (original) 20 to another material. I do. In this example, the fine irregularities formed on the surface of the hard layer 22 of the surface fine irregularities (original) 20 are transferred to another material, and a primary transfer product having a reverse pattern of the fine irregularities of the original on the surface is obtained. Then, the reverse pattern of the primary transfer product is transferred to another material to obtain the light distribution control sheet 10 of the illustrated example which is a secondary transfer product. As the transfer step, for example, a publicly known method disclosed in Japanese Patent No. 4683011 can be adopted.

  One aspect of the present invention is a method for producing a surface fine unevenness using the surface fine unevenness described above as an original plate.

  Specifically, an uncured ionizing radiation curable resin containing a release agent is accommodated in a thickness of, for example, 3 to 30 μm with respect to the fine unevenness of the surface fine unevenness 20 of FIG. After coating with a coater such as a die coater, roll coater, or bar coater and irradiating with ionizing radiation to cure, the original is peeled off to obtain a primary transfer product. The primary transfer product has a reversal pattern of fine irregularities of the original plate. On the other hand, a transparent base material 11 made of PET is prepared, and an uncured ionizing radiation curable resin is applied on one surface thereof with a thickness that sufficiently covers fine irregularities. Then, the surface of the applied uncured ionizing radiation curable resin is pressed against the surface having the reversal pattern of the previously obtained primary transfer product and cured by irradiation with ionizing radiation. Peel off the next transfer product. Irradiation with ionizing radiation may be performed from either one of the primary transfer product side and the transparent PET substrate side having ionizing radiation transparency. Thereby, it is composed of a transparent base material 11 made of PET and a surface layer 12 of a cured ionizing radiation curable resin formed on one surface thereof, and a figure with fine irregularities formed on the surface of the surface layer 12 1 and the light distribution control sheet (secondary transfer product) 10 shown in FIG.

  Examples of the ionizing radiation curable resin include an ultraviolet curable resin and an electron beam curable resin. The type of ionizing radiation to be irradiated is appropriately selected according to the type of resin. In general, the ionizing radiation often means ultraviolet rays and electron beams, but in the present specification, visible rays, X-rays, ion rays and the like are also included.

  Uncured ionizing radiation 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 methacrylate. 1 type selected from monomers such as prepolymers such as 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, etc. The thing containing the above component is mentioned. The uncured ionizing radiation curable resin is preferably diluted with a solvent or the like. A fluorine resin, a silicone resin, or the like may be added to the uncured ionizing radiation curable resin. When the uncured ionizing radiation curable resin is ultraviolet curable, it is preferable to add a photopolymerization initiator such as acetophenones and benzophenones to the uncured ionizing radiation curable resin.

  Also, instead of ionizing radiation curable resin, transfer is performed using, for example, thermosetting resin such as uncured melamine resin, urethane resin or epoxy resin, or thermoplastic resin such as acrylic resin, polyolefin or polyester. As long as fine irregularities can be transferred, the specific method and material to be transferred are not limited.

  In the case of using a thermosetting resin, for example, a method of applying a liquid uncured thermosetting resin to fine irregularities and curing it by heating is mentioned. When using a thermoplastic resin, a sheet of thermoplastic resin is used. There is a method of heating and softening while pressing against fine irregularities and then cooling.

  In addition, as described above, in the case of producing a secondary transfer product, for example, a method using a plating roll described in Japanese Patent No. 4683011 is also exemplified. Specifically, first, a long sheet-like material is manufactured as an original plate, the original plate is rounded and attached to the inside of a cylinder, plating is performed with a roll inserted inside the cylinder, and the roll is removed from the cylinder. Take out and obtain a plating roll (primary transfer product). Next, a light distribution control sheet (secondary transfer product) is obtained by transferring the fine irregularities of the plating roll.

  As the original plate, either a single wafer type or a web type can be used. If a web type master is used, a web type primary transfer product and a secondary transfer product can be obtained. In the single-wafer type, a stamp method using the single-wafer type original as a flat plate, a roll imprint method using a single-wafer type original wound around a roll as a cylindrical die, and the like can be applied. Further, a single-wafer type master may be arranged inside the mold of the injection molding machine. However, in the method using these single-wafer type masters, it is necessary to repeat the transfer many times in order to mass-produce the light spreading powder sheet as shown in the illustrated example. When the transferability (releasability) is low, clogging occurs in the fine unevenness to be transferred, and the transfer of the fine unevenness may be incomplete. On the other hand, when the original plate is a web type, fine irregularities can be transferred continuously in a large area, and a necessary amount of light distribution control sheet can be produced in a short time without repeating many transfers.

[Modification of manufacturing method of original plate and manufacturing method of fine surface irregularities by transfer using original plate]
In the above-described lamination process of [Original Plate Manufacturing Method], a coating liquid containing matrix resin 22a, particles 22b, and a solvent was used. However, a hard layer is formed using a coating liquid that does not contain particles and contains a matrix resin and a solvent, and is formed into a wavy uneven pattern by a deformation process, and then a large number of recesses or protrusions on the uneven pattern. May be formed. The method for forming the hard layer can be performed in the same manner as described above except that particles are not used. The deformation process can also be performed in the same manner as described above. Next, as a method for forming a large number of concave portions or convex portions on the formed concave / convex pattern, the following methods (5) to (8) are exemplified.
(5) A method of cutting with a rotary precision cutting machine.
(6) A method of forming a recess by pressing a projection having the same size and diameter as the recess or the protrusion onto the wavy uneven pattern.
(7) A method of forming a convex portion formed of the resin or the inorganic substance by adhering a fine resin or inorganic melt to the wavy uneven pattern and then solidifying it by cooling.
(8) A method in which a liquid in which a resin or an inorganic substance is dispersed in a dispersion medium is deposited on the wavy uneven pattern, and then the dispersion medium is evaporated to form a convex portion formed of the resin or the inorganic substance.

  In addition, by applying the inkjet printing method in the method (7) or (8), a large number of concave portions or convex portions can be formed on the wavy uneven pattern with high accuracy.

  In addition, a hard layer is formed using a coating liquid that does not contain particles and contains a matrix resin and a solvent, and is formed into a wavy uneven pattern by a deformation process (a large number of recesses or protrusions have not yet been formed) ) As an original plate, a transferred product may be obtained, and a plurality of concave portions or convex portions may be formed on the concavo-convex pattern by the above methods (5) to (8). And by transferring this as an original plate, it is possible to produce a surface fine unevenness.

<About other forms>
In the above description, using the surface fine unevenness produced by the laminating process and the deformation process as an original plate, a primary transfer product obtained by transferring the fine unevenness of the surface fine unevenness is obtained, and then the primary transfer product of The secondary transfer product to which the fine unevenness (reversal pattern of the original plate) was transferred was used as the light distribution control sheet 10.

  However, the present invention is not limited to the above form.

  That is, the surface fine unevenness 20 itself as shown in FIG. 11 manufactured by the above-described lamination process and deformation process can also be used as a light distribution control sheet. Moreover, the primary transfer product obtained by using the surface fine irregularities 20 produced by the lamination process and the deformation process as an original plate, and the n-th transfer product (n is an integer of 3 or more) are used as the light distribution control sheet. If it is a transfer product, it is not limited to a secondary transfer product.

  Moreover, you may transfer a fine unevenness | corrugation to the said curved surface of the molded object which has a curved surface using an original plate.

  Also, using the surface fine irregularities produced by the laminating process and the deformation process and the n-order transfer product as an original plate, a transparent thermoplastic resin such as an acrylic resin or a polycarbonate resin is injection-molded, and the fine irregularities are at least on the surface. You may manufacture the injection molded product formed in part.

  In the n-order transfer product obtained by using the surface fine irregularities 20 produced by the laminating process and the deformation process specifically shown above as an original plate, when n is an odd number, as the fine irregularities, a specific corrugation On the concave / convex pattern, concave portions are formed instead of convex portions. This is because in the n-th order transfer product in which n is an odd number, a reverse pattern of the convex portion formed based on the particles, that is, a concave portion is formed. As described above, even if the surface fine concavo-convex body having a concave portion together with a specific wavy concavo-convex pattern as the fine concavo-convex pattern, since the anisotropy due to the wavy concavo-convex pattern is weakened by the concave portion, sufficient FWHM in the direction Y And also has some FWHM in direction X. Therefore, even if the n-order transfer product has an odd number n, the light distribution control performance is equivalent to that of the n-order transfer product where n is an even number.

  As the particles used for forming the hard layer, resin particles and inorganic particles can be used, and any material can be used as long as it is not melted or deformed in the deformation process or the process of transferring fine irregularities. It may be. However, as described above, when the surface fine irregularities 20 having the particles themselves as shown in FIG. 11 are used as the light distribution control sheet, the particles are transparent particles, preferably acrylic cross-linked resin particles, glass It is preferable to use beads, polystyrene-based crosslinked resin particles, and the like.

  Moreover, in the above example, although a sheet-like thing was illustrated as a surface fine unevenness | corrugation body and a light distribution control sheet, it is not limited to a sheet-like thing, A solid molded object may be sufficient.

  Further, the fine unevenness may be formed in any part depending on the purpose as long as it is at least a part of the surface of the surface fine unevenness. For example, when the surface fine unevenness is a sheet-like material, it may be formed on only one surface, on both surfaces, or may be formed on only part of each surface, You may form in at least one part of the surrounding surface (end surface) of a thing.

  Furthermore, even when the surface fine irregularities are three-dimensional molded bodies, they may be formed on the entire surface or only on a part thereof. In addition, when the surface fine unevenness | corrugation body is a three-dimensional molded object, the said three-dimensional molded object can be used for the use similar to the use illustrated about the light distribution control sheet. That is, a light distribution control member for a projector; a light distribution control member for a backlight of a television, a monitor, a notebook personal computer, a tablet personal computer, a smartphone, a mobile phone, etc., an LED light source used for a copying machine, etc. In a linearly arranged scanner light source, it can be suitably used as a light distribution control member that constitutes at least the exit surface of the light guide member.

  The present inventors measured front luminance and whitening return using each light distribution control sheet (secondary transfer product) sample having various FWHMs produced by the method described above.

  The magnitude of the front luminance was evaluated using the relative front luminance shown below.

  When various light distribution control sheets were used for the display, the luminance in the front direction was measured using a luminance meter (UA-1000 manufactured by TOPCON), and the maximum luminance in the display surface was determined. The relative front luminance was calculated as a ratio between the obtained maximum luminance and the minimum luminance necessary for the display. That is, if the relative front luminance is smaller than 1, sufficient luminance cannot be obtained, and if the relative front luminance is 1 or larger, sufficient luminance is obtained. The minimum luminance required for the display was the luminance when a general-purpose light diffusion plate having a transmittance of 80% was used as a light distribution control sheet. Moreover, the display used for the measurement has LED as a light source, and in addition to the light distribution control sheet, a general specification having various optical layers such as a prism sheet is used. About the magnitude | size of the effect of white return, it evaluated using the white return parameter | index shown below.

  The light emitted from the backlight of the display using the light distribution control sheet is projected onto white paper, and the color at the center of the projected image: the difference between CS1 and the color GS1 at the outer periphery of the projection is obtained, and the color at the center The difference in color between the color and the outer peripheral color Δ: | CS1-GS1 | / CS1 was 20%, and the color difference was defined as the standard color difference of the white return index. The present inventors consider that if | CS1-GS1 | / CS1 is within 20%, it is not recognized as an unpleasant color difference by human eyes. The relative white return index of the display using various light distribution control sheets was calculated as “color difference of target sample / standard color difference of white return index”. That is, if the relative white return index is greater than 1, there is no sufficient white return effect as a display, and if the relative white return index is 1 or less, there is a sufficient white return effect as a display. The color was measured using a luminance meter (UA-1000 manufactured by TOPCON). Further, the color in the present invention refers to chromatility when measured with a luminance meter (UA-1000 manufactured by TOPCON).

  The increase and decrease of the white return effect in the X and Y directions depends on the size of the light distribution control function of the light distribution control sheet, but the present inventors consider that the mechanism of the light distribution control mainly follows the principle of light refraction. . Since the refraction of light depends on the fine uneven shape of the light distribution control sheet, the present inventors analyzed the uneven shape of the light distribution control sheet samples having various FWHMs by the following method.

The inventors of the present invention observed the uneven shapes of various light distribution control sheet samples in detail using a laser microscope. FIG. 13 (a) (laser microscope image of the light distribution control sheet) is a laser micrograph (horizontal; 780 μm, observing fine irregularities of the light distribution control sheet sample with a laser microscope (“VK-X110” manufactured by Keyence Corporation). Vertical; 570 μm). FIG. 13B (height profile of the light distribution control sheet sample) shows a height profile cut in the horizontal direction in FIG. 13A along the line α. In the height profile of FIG. 13B, tangent lines are drawn at points at intervals of 1.8 μm, and the situation is shown in FIG. FIG. 14A shows a state of an example in which a tangent line is drawn at each point (contact point) at intervals of 1.8 μm in a part of the height profile of the cross section of the surface fine unevenness. The inclination of the tangent at the point U in FIG. (A) will be described with reference to FIG. The slope angle θ _U at the point _U is defined by the following equation (2) from the tangent slope A _U (= height / 1.8) at the point _U (FIG. 14 (b)) (method for calculating the slope angle θ _U ) . Formula (2); A _U = tan θ _U

When the observation target sample is a light distribution control sheet in which the mode pitch of the fine irregularities is 5 to 50 μm and the mode height is 0.3 to 10 μm, it is appropriate to draw the tangent line I at intervals of 1.8 μm. . When the tangent line I is drawn at an interval larger than 1.8 μm, for example, 2.0 μm or more, it is not preferable because the fine irregularities cannot be accurately analyzed. Conversely, when tangent lines are drawn at a small interval of 1.7 μm or less, the direction should be able to be analyzed more precisely, but according to the present inventors' trial, there was almost no numerical influence. When the most frequent pitch is less than 5 μm, it is preferable to set the interval between the tangent lines I to 1.8 μm or less. For example, it is preferable to set the interval of the tangent line I to about 1/4 times or less of the most frequent pitch. Incidentally, when the gradient of the tangent A is a negative value, finding the slope angle theta _U from returning to a positive value.

In the subsequent calculations, a height profile is taken for each line taken at intervals of 0.13 μm parallel to the line α in FIG. 13 (a) (laser microscope image of the light distribution control sheet), and at each 1.8 μm interval for each height profile. Calculates the slope angle, stores all the slope angles in the field of view of FIG. 13 (a) (laser microscope image of the light distribution control sheet), and accumulates data for calculating the frequency (frequency of the value A) did.
In FIG. 13A, the fine unevenness of the light distribution control sheet is apparently seen in a wavy uneven pattern having a plurality of ridges meandering with each other and a ridge between the plurality of ridges. There is no fear. In the figure, the region that seems to have a flat shape also has a small uneven shape when taking a height profile by a laser microscope, exhibits a fine uneven shape, and a plurality of ridges meandering with each other, It has been confirmed that a wavy uneven pattern having a concave portion between a plurality of convex portions is formed.

FIG. 15 and FIG. 16 show an example of the frequency distribution graph of the slope angle of the sample of the light distribution control sheet showing FWHM _Y = 20 ° and FWHM _X = 10 °. FIG. 15 is a frequency distribution graph of the tangential slope angle when the Y direction of the light distribution control sheet is analyzed by the above method. FIG. 16 is a graph when the X direction of the light distribution control sheet is analyzed by the above method. It is a frequency distribution graph of the tangent slope angle.
From FIG. 15 (FWHM _Y = 20 ° slope angle frequency distribution graph) and FIG. 16 (FWHM _X = 10 ° slope angle frequency distribution graph), the wider the FWHM, the higher the frequency of the point with the larger slope angle. (See FIG. 15), it was found that when the FWHM is narrow, the frequency of points with a small slope angle increases (see FIG. 16).

The inventors measured the slope angle for each of the X direction and Y direction of the light distribution control sheet having various FWHMs, and the average values of the slope angles in the X direction and the Y direction were negatively correlated with the relative front luminance, respectively. It was found to have That is, when the average slope angle _x is small, the relative front luminance increases, and when the average slope angle _x is large, the relative front luminance decreases. Further, when the average slope angle _y is small, the relative front luminance increases, and when the average slope angle _y is large, the relative front luminance decreases. However, the light distribution control sheet further having various FWHM, was examined the correlation between the average slope angle _x relative front brightness or the average slope angle _y relative front brightness, from the average slope angle _x or the average slope angle _y The present inventors have found a light distribution control sheet having a significantly lower relative front luminance than expected relative front luminance.

The inventors of the present invention analyzed the light distribution control sheet having a relatively small relative front luminance in more detail. As a result, the light distribution control sheet having a small relative front luminance has either the average slope angle _x or the average slope angle _y. Was found to be extremely large. For example, it was found that the light distribution control sheet having a significantly smaller relative front luminance than the relative front luminance expected from the average slope angle _x has an extremely large average slope angle _y . Therefore, the present inventors examined the correlation between the average value of the average slope angle _x and the average slope angle _y and the relative front luminance, and found that there is a negative correlation between the two.

FIG. 17 shows the relationship between (average slope angle _x + average slope angle _y ) / 2 and relative front luminance of various light distribution control sheet samples. FIG. 17 shows that (average slope angle _X + average slope angle _Y ) / 2 and the relative front luminance have a negative correlation. That is, when (average slope angle _X + average slope angle _Y ) / 2 is widened, the relative front brightness decreases, and conversely, when (average slope angle _X + average slope angle _Y ) / 2 is narrowed, the relative front brightness is increased. I found out that Furthermore, it was found that if the (average slope angle _X + average slope angle _Y ) / 2 was 4.7 ° or less, sufficient relative front luminance (1 or more) was obtained. In order to obtain sufficient relative front luminance, (average slope angle _X + average slope angle _Y ) / 2 is preferably 4 ° or less, and in order to obtain better relative front luminance (average slope angle). More preferably, _X + average slope angle _{Y 1} ) / 2 is 3 ° or less.

FIG. 18 shows the relationship between various light distribution control sheet samples and the relative white return index in the Y direction. As shown in FIG. 18, when the average slope angle _Y and the relative white return index in the Y direction have a negative correlation and the average slope angle _Y is equal to or greater than 2.4 °, the inventors of the present invention have sufficient relative values in the Y direction. It was found that a whiteness return index (1 or less) was obtained. Although the average slope angle _X and the relative white return index in the X direction also show a negative correlation, no matter how many times the average slope angle _X is (that is, 0 ° or more), a sufficient X direction It was found that a relative white return index (1 or less) was obtained. In addition, about the upper limit of the average slope angle _Y , 7 degrees or less are more preferable, 6.5 degrees or less are more preferable, and 5 degrees or less are especially preferable. Further, the upper limit value of the average slope angle _x is more preferably 3 ° or less, further preferably 2.5 ° or less, and particularly preferably 2 ° or less.

In general, the display rarely requires the same viewing angle in the longitudinal direction of the display, for example, the direction Y and the direction X substantially orthogonal to the direction Y. Therefore, various optical characteristics often have directionality even in optical control members other than the light distribution control sheet constituting the display. Therefore, the present inventors consider that a sufficient relative white return index in the X direction is obtained regardless of the number of average slope angles in the X direction of the light distribution control sheet in the present invention.

As a result of the study, the present inventors have found that when (average slope angle _Y −average slope angle _{X 1} ) is small, the relative white return index in the X direction is larger than the relative white return index in the Y direction. When there is a difference of 0.15 or more in the relative white return index between the X direction and the Y direction, the color when the display is tilted with respect to the Y direction and when tilted with respect to the X direction This is not preferable as a display. For use as a light distribution control member for a projector or a light distribution control member for a backlight of a liquid crystal display, (average slope angle _Y −average slope angle _{X 1} ) is preferably 0.5 ° or more, preferably 1 °. More preferably.

From the above, satisfying (average slope angle _X + average slope angle _Y ) /2≦4.7° and average slope angle _Y ≧ 2.4 ° at the same time of the light distribution control member for projector and the liquid crystal display It turned out that it is suitable as a light distribution control member for backlights. Further, while satisfying (average slope angle _X + average slope angle _Y ) /2≦4.7° and average slope angle _Y ≧ 2.4 ° simultaneously, (average slope angle _Y −average slope angle _X ) ≧ 0. It was found that satisfying 5 ° at the same time is more suitable as a light distribution control member for a projector and a light distribution control member for a backlight of a liquid crystal display.

(Each sample)
As described above, in the present invention, light distribution control sheet samples having various FWHMs were prepared and repeated trials, but the FWHM of the light distribution control sheet was determined by the heat-shrinkage of the hard layer in the above-described examples. Various samples were prepared by arbitrarily changing the shrinkage rate, stretching rate, etc. of the film.

Hereinafter, the present invention will be specifically described by way of examples.

Example 1
The following coating liquid (1) is coated on one side of a polyethylene terephthalate biaxial heat shrinkable film (“PX-40S” manufactured by Mitsubishi Plastics, Inc.), thickness: 25 μm, glass transition temperature Tg1 = 75 ° C. The subsequent hard layer was coated with a bar coater (Meyer bar # 22) so that the thickness t ′ was 4 μm to obtain a laminated sheet.

(Coating fluid (1))
In addition to acrylic resin A (glass transition temperature Tg2 = 100 ° C.) and toluene, a coating liquid (1) having a solid content concentration of 10% by mass was obtained (that is, acrylic resin A was used as the solid content, and toluene was used as the solvent content). And a coating liquid (1) having a solid content concentration of 10% by mass was obtained). In addition, although the said acrylic resin A is solid content concentration of 23 mass%, the mass ratio and density | concentration in this example are the values calculated by the net amount (solid content amount). The following examples are also calculated with the net amount.
Next, the laminated sheet is heated at 110 ° C. for 0.5 minutes using a hot air oven to heat-shrink the polyethylene terephthalate biaxial heat-shrinkable film in one direction to 75% of the length before heating. (Deformation rate is 25%) In the other direction substantially orthogonal to one direction, heat shrinkage is performed to 85% of the length before heating (deformation rate is 15%), and the hard layer is deformed to be folded. Thereby, the surface fine uneven sheet | seat (original) in which the wavy uneven pattern was formed in the surface of the layer was obtained. In addition, each of the formed ridges meandered and was irregularly formed.
An uncured UV curable resin A (manufactured by Soken Chemical Co., Ltd.) containing a release agent is applied to the surface of the surface fine uneven surface of the obtained surface fine uneven sheet (original) so as to have a thickness of 20 μm and irradiated with ultraviolet rays. And cured, and then peeled to obtain a primary transfer product having a reversal pattern of fine unevenness of the surface fine unevenness sheet. Next, an uncured UV curable resin B (manufactured by Sony Chemical Co., Ltd.) was applied to one side of a transparent PET base material (“A4300” manufactured by Toyobo Co., Ltd., thickness: 188 μm) to a thickness of 20 μm. The surface of the primary transfer product having the above reversal pattern is pressed against the ultraviolet curable resin B, cured by irradiating with ultraviolet rays, and after curing, the primary transfer product is peeled off, and then on the transparent PET substrate. A light distribution control sheet (secondary) in which a surface layer made of a cured product of an ultraviolet curable resin is formed, and on the surface of the surface layer, the same fine unevenness as the above-mentioned surface fine unevenness sheet (original) is formed. A transcription product) was obtained.

(Example 2)
The following coating liquid (2) is applied to one side of a polyethylene terephthalate uniaxial heat shrinkable film (“SC807” manufactured by Toyobo Co., Ltd., thickness: 30 μm, glass transition temperature Tg3 = 80 ° C.). Coating was performed with a bar coater (Meyer bar # 8) so that the thickness t ′ was 0.7 μm to obtain a laminated sheet.

(Coating fluid (2))
In addition to acrylic resin B (glass transition temperature Tg4 = 128 ° C.) and toluene, a coating liquid (2) having a solid content concentration of 8% by mass was obtained (that is, acrylic resin B was used as the solid content, and toluene was used as the solvent content). And a coating liquid (2) having a solid content concentration of 8% by mass was obtained).
Next, the laminated sheet is heated at 180 ° C. for 0.5 minutes using a hot air oven to heat-shrink the polyethylene terephthalate uniaxial heat-shrinkable film to 50% of the length before heating (as the deformation rate). 50%), the hard layer was deformed to fold. Next, by heating at 180 ° C. for 1 minute, the film was stretched to 100% of the length before heating in the direction opposite to the contraction direction in the uniaxial direction (0% as the deformation rate). Furthermore, by heating at 180 ° C. for 1 minute, the film was stretched to 160% of the length before heating in the other direction substantially orthogonal to one direction (−60% as a deformation rate). Thereby, the surface fine uneven sheet | seat (original) in which the wavy uneven pattern was formed in the surface of the layer was obtained. About the obtained surface fine unevenness | corrugation sheet (original), it is the same as Example (1) below, The light distribution control sheet (secondary transfer product) in which the same fine unevenness | corrugation as said surface fine unevenness | corrugation sheet (original) was formed Got.

(Example 3)
The following coating solution (3) was applied to one side of a polyethylene terephthalate uniaxial heat-shrinkable film (“SP-809” manufactured by Toyobo Co., Ltd.), thickness: 30 μm, glass transition temperature Tg5 = 75 ° C. Coating was performed with a bar coater (Meyer bar # 32) so that the thickness t ′ of the hard layer was 5.5 μm, and a laminated sheet was obtained.

(Coating liquid (3))
In addition to acrylic resin B (glass transition temperature Tg4 = 128 ° C.) and toluene, a coating liquid (3) having a solid content concentration of 12% by mass was obtained (that is, acrylic resin B was used as the solid content, and toluene was used as the solvent content). And a coating liquid (3) having a solid content concentration of 12% by mass was obtained). In addition, although the said acrylic resin B is solid content concentration of 23 mass%, the mass ratio and density | concentration in this example are the values calculated by the net amount (solid content amount). The following examples are also calculated with the net amount.
Next, the laminated sheet is heated at 180 ° C. for 0.5 minutes using a hot air oven to heat-shrink the polyethylene terephthalate uniaxial heat-shrinkable film to 63% of the length before heating (as the deformation rate). 37%), the hard layer was deformed to fold. Thereby, the surface fine uneven sheet | seat (original) in which the wavy uneven pattern was formed in the surface of the layer was obtained. About the obtained surface fine unevenness | corrugation sheet (original), it is the same as Example (1) below, The light distribution control sheet (secondary transfer product) in which the same fine unevenness | corrugation as said surface fine unevenness | corrugation sheet (original) was formed Got.

Example 4
In Example 3, a light distribution control sheet was obtained in the same manner as in Example 3 except that the heat shrinkage process was changed to 63% and heat shrinkage of 70% (deformation rate: 30%) was performed.

(Example 5)
In Example 3, a light distribution control sheet was obtained in the same manner as in Example 3 except that the heat shrinkage step was changed to 63% and heat shrinkage of 67% (deformation rate: 33%) was performed.

(Example 6)
In Example 2, a light distribution control sheet was obtained in the same manner as in Example 2 except that the stretching step was changed to 100% and stretching was performed up to 93% (7% as a deformation rate).

(Comparative Example 1)
In Example 2, instead of the 50% shrinking step, 60% (40% deformation rate) heat shrinkage was performed, and the stretching step up to 160% in the other direction substantially orthogonal to one direction was omitted. Except for the points, a light distribution control sheet was obtained in the same manner as in Example 2.

(Comparative Example 2)
In Example 3, a light distribution control sheet was obtained in the same manner as in Example 3 except that the heat shrinkage step was changed to 63% and heat shrinkage of 80% (20% as a deformation rate) was performed.

(Evaluation)
About the light distribution control sheet obtained in each of the above examples, the FWHM, the average value of the slope angle, the relative front luminance, and the relative white return index were measured by the methods described above. The relative front luminance was determined to be 1 or more, ○, less than 1, x, and the relative white return index in the Y direction being less than 1, ○, 1 or more.
The results are shown in Table 1.

10: Light distribution control sheet, 13: Wavy uneven pattern, 13a: Convex part, 13b: Concave part, 14: Convex part, 20: Surface fine unevenness (original), 21: Base material, 22: Hard layer 22a: matrix resin, 22b: particles, 31: base film, 32: hard layer (undeformed)

Claims (3)

It is a surface fine uneven body in which fine unevenness is formed on at least a part of the surface,
The height of the cross-section of the fine unevenness of the surface fine unevenness in each direction of the direction Y in which light passing through the surface on which the fine unevenness is formed is most widely distributed and the direction X substantially orthogonal to the direction Y In the profile, a fine surface irregularity body in which tangent lines are drawn at predetermined intervals, and the average value of the slope angle (average slope angle _Y and average slope angle _X ) of each contact satisfies the following formulas (a) to (b).
Average slope angle _X + average slope angle _Y ) /2≦4.7° (a)
Average slope angle _Y ≧ 2.4 ° (b)   The surface fine concavo-convex body according to claim 1, wherein the fine concavo-convex has a wavy concavo-convex pattern having a plurality of ridges meandering with each other and a ridge between the plurality of ridges.   The surface fine unevenness according to claim 1 or 2, wherein the predetermined interval is less than 2.0 µm.