JP2009128645A - Method of manufacturing optical sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a white line from being generated, when manufacturing an optical sheet with light shielding parts arranged like stripes in parallel, by filling a plurality of grooves on a surface of a translucent base material sheet with a light-shielding material, and by scraping the excessive light-shielding material. <P>SOLUTION: The light-shielding material 40 is applied on a face of the grooves 15 in the translucent base material sheet 10 with the plurality of grooves 15 on the surface. The light-shielding material 40 on the surface of the translucent base material sheet is scraped by a scraping jig 30, so that the light-shielding material 40 remains in the grooves 15. The optical sheet having light-shielding stripes 20 is manufactured thereby in this manufacturing method for the optical sheet, and a relative moving direction of the scraping jig 30 with respect to the translucent base material sheet 10 crosses a longitudinal direction C of each groove 15. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for forming a stripe, and a method for producing an optical sheet using this method to form a light-shielding stripe on a light-transmitting substrate sheet.

  Conventionally, as a viewing angle control sheet installed on the front surface of a display, a light-transmitting layer and a light-shielding layer are alternately laminated, and sliced perpendicularly to the stacking method, whereby a stripe-shaped light-transmitting portion and a light-shielding portion are alternately arranged. An arrayed optical sheet is known (Patent Document 1). However, with this method, it is difficult to produce an optical sheet in a large area, and the production efficiency is very low.

  Further, a transparent base sheet having a large number of V-shaped grooves arranged in parallel is prepared, a light shielding material is applied to the parallel surfaces of the grooves, and the grooves are filled with the light shielding material. There is known a method of manufacturing an optical sheet in which stripe-shaped light-transmitting portions and light-shielding portions are alternately arranged by scraping off (Patent Document 2). According to this method, a sheet having a large area can be easily manufactured as compared with the method of Patent Document 1, and the production efficiency is high. However, in this method, when scraping off the light-shielding material filled in the groove, foreign matter bites between the base sheet and the scraping jig, resulting in white streak defects (hereinafter referred to as white lines), The appearance of the optical sheet may be impaired. On the other hand, Patent Document 2 proposes laminating a colored layer on the formation surface of the light-shielding portion of the transparent base sheet, but the white line is less noticeable due to the lamination of the colored layer, but the occurrence of the white line It is not itself suppressed. In addition, there is a problem that light is lost due to the presence of the colored layer.

Japanese Patent Laid-Open No. 50-092751 JP 2006-178092 A

  In contrast to the above-described prior art, the present invention is that the filling material is filled in the groove of the base sheet having a plurality of grooves arranged in parallel on the surface, and the filling material is scraped off the filling material. An object of the present invention is to provide a method capable of suppressing the generation of white lines and to produce an optical sheet having a good appearance of the light-shielding stripe by using this method.

  The present inventor, after filling a light-shielding material in a groove arranged in parallel with the base material sheet, even if foreign matter bites into the scraping jig when scraping off the extra light-shielding material, If the scraping operation is performed so that it moves toward the wall, the foreign matter will come off the scraping jig by hitting the groove wall, the white line will stop growing, and the white line can be prevented from being damaged. I found it.

  That is, according to the present invention, as a first stripe forming method, a filling material is applied to the parallel surface of the grooves of the base sheet having a plurality of grooves arranged on the surface, and the filling material is left in the grooves. In this method, the stripping material is formed on the base sheet by scraping the filling material on the surface of the base sheet with a scraping jig, and the relative movement direction of the scraping jig with respect to the base sheet is grooved. A method for forming a stripe characterized by intersecting with the longitudinal direction of the light-transmitting substrate sheet, and as a method for producing an optical sheet using this method, An optical sheet having a light-shielding stripe by applying a light-shielding material on the side-by-side surfaces of the grooves and scraping the light-shielding material on the surface of the translucent substrate sheet with a scraping jig so as to leave the light-shielding material in the grooves. A method for manufacturing a transparent substrate sheet The direction of relative movement of the jig to provide a method for producing an optical sheet, characterized in that to cross the longitudinal direction of the groove.

  Further, in the present invention, as a second stripe forming method, a filling material is applied to the parallel surface of the grooves of the base sheet having a plurality of grooves arranged on the surface, and the filling material is left in the grooves. In this way, a stripe of the filling material is formed on the base sheet by scraping the filling material on the surface of the base sheet with a scraping jig, and the longitudinal direction of the contact portion of the scraping jig with respect to the base sheet is determined. Provided is a stripe forming method characterized in that it is oblique to the groove arrangement direction and the direction of relative movement of the scraping jig with respect to the base sheet is the longitudinal direction of the groove, and an optical sheet using this method As a manufacturing method, a light-shielding material is applied to the side-by-side surface of the light-transmitting base sheet having a plurality of grooves arranged on the surface, and the light-shielding material is left in the grooves. The light shielding material on the surface of the base sheet is scraped with a scraping jig, A method of manufacturing an optical sheet having a tape, wherein the longitudinal direction of the contact portion of the scraping jig with respect to the translucent substrate sheet is inclined with respect to the direction of arrangement of the grooves, and scraping with respect to the translucent substrate sheet is performed. Provided is a method for manufacturing an optical sheet, wherein the relative movement direction of the jig is the longitudinal direction of the groove.

  According to the first stripe forming method of the present invention, since the relative movement direction of the scraping jig with respect to the base sheet intersects with the longitudinal direction of the groove, each point in contact with the base sheet of the scraping jig is Move across multiple grooves. Therefore, the foreign matter biting into the scraping jig at the time of scraping hits the groove wall with the movement of the scraping jig and comes off the scraping jig.

  According to the second stripe forming method of the present invention, the longitudinal direction of the contact portion of the scraping jig with respect to the base sheet is inclined with respect to the arrangement direction of the grooves, The relative moving direction is the longitudinal direction of the groove. For this reason, the foreign matter that bites into the scraping jig during scraping is easily removed from the scraping jig due to the force of the slanting rearward direction with respect to the moving direction of the scraping jig as the scraping jig moves. Furthermore, it hits the groove wall and comes off the scraping jig.

  Thus, the foreign matter biting the scraping jig is removed from the scraping jig by either the first stripe forming method or the second stripe forming method, and the growth of the white line stops there. The foreign matter bitten by the scraping jig is dragged over a long distance in the longitudinal direction of the groove, and a long white line is not formed.

  Therefore, according to the manufacturing method of the optical sheet of the present invention in which the first or second stripe forming method is used for forming the light shielding stripe, the white line is hardly generated in the light shielding stripe and the white line is generated. Even in this case, the growth stops in a short time, and the length of the white line is shortened. It should be noted that the foreign matter that has come out of the scraping jig by hitting the groove is buried in the light-shielding material and is hardly noticeable. Therefore, according to the method for producing an optical sheet of the present invention, an optical sheet with improved appearance can be obtained.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In each figure, the same numerals indicate the same or equivalent components.

  FIG. 1 is a perspective view of an embodiment of an optical sheet manufactured by the method of the present invention, and FIG. 2 is an xx sectional view thereof. The optical sheet 1 is an optical sheet 1 that is used as a viewing angle control filter, a diffusivity control filter, a contrast improvement filter, and the like, and has a light-shielding stripe 20 on one side of a translucent substrate sheet 10. The light-shielding stripes 20 are formed from columnar light-shielding portions 21 that are alternately arranged with the prism rows 11 formed on the surface of the translucent substrate sheet 10.

  In the cross section of the optical sheet 1, the prism row 11 is substantially trapezoidal, the light shielding portion 21 is substantially V-shaped, and the shoulder portion 14, which is the intersection of the upper surface 12 and the inclined surface 13, is rounded (curvature). Radius R) is attached. Due to this roundness, when the translucent substrate sheet 10 is molded with a mold, the molten resin is filled to the back of the mold to eliminate unevenness of the molded shape of the shoulder portion 14 and can be removed from the mold. Making it easy.

  The pitch P of the light-shielding stripes 20 is 300 μm or less from the viewpoint of increasing the definition of images when the optical sheet 1 is mounted on the front surface of a plasma display, a liquid crystal display or the like and used as a display filter that improves contrast and the like. Moreover, it is preferable to set it as 30 micrometers or more from the point of durability of the metal mold for shaping | molding of the transparent base material sheet 10, or a moldability.

  The height L1 of the light-shielding portion 21 and the width L2 of the light-shielding portion are set as appropriate from the viewpoint of the viewing angle to be controlled and the ease of molding.

  The ratio L2 / P between the width L2 and the pitch P of the light-shielding portion 21 can be selected according to the desired light diffusion performance, but is usually preferably about 0.1 to 0.7.

  The layer thickness L3 of the translucent substrate sheet 10 is an important factor that affects the transfer performance of the prism array 11 when the prism array 11 is manufactured to have a high aspect ratio by extrusion molding. (Height of light-shielding portion) It is preferably 1.5 to 3.5 times L1.

  As a manufacturing method of the optical sheet 1, first, a translucent substrate sheet 10 having a prism row 11 on the surface is formed. The translucent substrate sheet 10 is preferably formed by extrusion using a thermoplastic resin such as an acrylic resin, a styrene resin, or a polycarbonate resin. In this extrusion molding, a mold having irregularities arranged in a shape opposite to the arrangement of the prism rows 11 is used. As the mold, a flat mold may be used, but it is preferable to use a roll molding mold in which grooves corresponding to the prism rows 11 are formed in the circumferential direction.

  The translucent substrate sheet 10 is manufactured by a method (2P molding method (Photo Polymerization)) in which an ultraviolet curable resin is filled between a transparent sheet and a molding die instead of extrusion molding. May be. However, since the ultraviolet curable resin is expensive, it is preferable to perform extrusion molding of a thermoplastic resin. In addition, the translucent base material sheet 10 can be manufactured also by hot press molding.

  After manufacturing the translucent substrate sheet 10, the light shielding material 21 is formed by filling the grooves 15 between the prism rows 11 with the light shielding material. The light-shielding portion 21 is formed using the first stripe forming method of the present invention or the second stripe forming method of the present invention.

  In addition, there is no restriction | limiting in particular in the light-shielding material itself which forms the light-shielding part 21, For example, the black ink and white ink containing light-shielding particle | grains can be used. Specific examples of the light shielding particles include carbon particles, resin fine particles, glass fine particles, metal oxide fine particles, and various pigments. The particle size of the light-shielding particles is preferably 1 μm or more from the viewpoint of concealing properties, preferably from 1/3 or less of the groove width from the viewpoint of filling properties into the grooves 15, and usually 30 μm or less.

  Examples of the ink binder for dispersing the light-shielding particles include an ultraviolet curable resin, a thermosetting resin, and a solvent-based adhesive. In addition, when not aiming at the improvement of external light contrast, the light shielding material may be white.

  FIG. 3 is an explanatory diagram of an embodiment of a method for forming a light-shielding stripe in accordance with the first stripe forming method of the present invention. In this method, the light shielding material 40 is applied to the formation surface (that is, the parallel surface of the grooves 15) of the prism row 11 of the translucent substrate sheet 10 by a conventional method, and the light shielding material 40 is left in the grooves 15. Thus, when scraping off the light-shielding material 40 on the surface of the translucent substrate sheet with the scraping jig 30, the longitudinal direction A of the contact portion between the scraping jig 30 and the translucent substrate sheet 10 is the groove 15. The scraping jig 30 and the translucent base sheet 10 are installed so as to be in the arrangement direction, and the relative movement direction B of the scraping jig 30 with respect to the translucent base sheet 10 is defined as the longitudinal direction C of the groove 15. Cross. Here, as the scraping jig 30, a rubber or metal squeegee, a blade knife, a rubber roll, a metal roll, a roll knife, or the like can be used. The relative movement direction B of the scraping jig 30 with respect to the translucent substrate sheet 10 is a scraping direction when the scraping jig 30 is moved relative to the fixed translucent substrate sheet 10. And the scraping direction when moving the translucent substrate sheet 10 with respect to the fixed scraping jig 30, and the case where both the translucent substrate sheet 10 and the scraping jig 30 are moved. It is intended to include any scraping direction. When the scraping jig 30 is a rubber roll or a metal roll, the scraping direction refers to the moving direction of the contact portion between the rubber roll or metal roll and the translucent base sheet in the translucent base sheet.

  As shown in FIG. 3, according to this method, each point of the scraping jig 30 in contact with the translucent substrate sheet 10 moves across the plurality of grooves 15. Therefore, the foreign matter 41 biting into the scraping jig 30 at the time of scraping moves toward the wall surface of the groove 15 as indicated by an arrow D along with the movement of the scraping jig 30 and hits the wall surface of the groove 15 to scrape the jig. Deviate from 30. The foreign matter 41 removed from the scraping jig 30 is buried in the light-shielding material 40 and is hardly noticeable. Therefore, according to the method for producing an optical sheet of the present invention, it is possible to obtain an optical sheet with improved appearance by suppressing the occurrence and growth of white lines.

  The angle θ1 at which the scraping direction B of the scraping jig 30 intersects the longitudinal direction B of the groove 15 is preferably 3 ° or more. If this angle θ1 is smaller than 3 °, the effect of the present invention may not be obtained. On the other hand, the scraping jig 30 needs to be formed longer than the width of the translucent substrate sheet 10 in the arrangement direction of the grooves 15, but if the angle θ1 is larger than 60 °, the scraping jig 30 This required length is increased, which increases the cost, which is not preferable.

  The scraping direction B may be a linear direction as shown in FIG. 4 (a), may be a broken line shape as shown in FIG. 4 (b), or is a wavy line shape as shown in FIG. 4 (c). It is good.

  When the transparent substrate sheet 10 is long, particularly when it is a continuous sheet, it is preferable to change the scraping direction B into a broken line shape or a wavy line shape. Thereby, the length of the scraping jig 30 required in the arrangement direction of the grooves 15 can be reduced.

  Here, if the scraping direction B is changed to a wavy line, the scraping direction B coincides with the longitudinal direction C of the groove in the vicinity of the time when the scraping direction changes, but if the scraping direction B is changed to a broken line, the scraping direction B is preferable because it always intersects the longitudinal direction C of the groove. On the other hand, it is preferable to change the scraping direction B to a wavy line in that the stepwise scraping unevenness is less likely to occur at the portion where the scraping direction changes compared to the case where the scraping direction is changed to a broken line.

  When the scraping direction A is periodically changed to a broken line shape or a wavy line shape, the amount of movement of the scraping jig 30 per half cycle is equal to or more than 5 rows of the groove 15, particularly 10 rows or more. It is preferable to adjust the moving speed of the scraping jig 30 and the scraping direction B.

  In addition, when the scraping direction B is a broken line or a wavy line, if the stepwise scraping unevenness at the portion where the scraping direction changes is a problem, the moving speed and scraping of the scraping jig 30 are determined. If the frequency of changing the scraping direction is increased by adjusting the removal direction, unevenness may be less noticeable. Specifically, the scraping jig 30 is moved so that the horizontal stage (interval of the horizontal streaky unevenness 42) shown in FIG. 4B is 1 cm or less in the longitudinal direction of the groove, preferably 1 mm or less. Adjust the speed and the amplitude and period of scraping direction B.

  When the light-shielding stripe is formed according to the first stripe forming method of the present invention, the longitudinal direction A of the contact portion between the scraping jig 30 and the translucent substrate sheet 10 is as shown in FIG. Instead of being in the arrangement direction of the grooves 15, the longitudinal direction A of the contact portion between the scraping jig 30 and the translucent substrate sheet 10 is set to the arrangement direction of the grooves 15 as shown in FIG. 5. It may be slanted.

  Also in this method, the scraping jig B is made to cross the longitudinal direction C of the groove 15 with the scraping direction B of the scraping jig 30 with respect to the translucent substrate sheet 10, similarly to the method shown in FIG. Since the foreign matter biting on 30 can be applied to the wall surface of the groove 15 by the movement of the scraping jig 30 and removed from the scraping jig 30, the optical sheet is improved in appearance by suppressing the generation and growth of white lines. Can be obtained. In particular, by arranging the scraping jig 30 at an angle and making the scraping direction B into a polygonal line or a wavy line, the effect of suppressing the generation and growth of white lines can be increased.

  FIG. 6 is an explanatory diagram of an embodiment of a method for forming a light-shielding stripe according to the second stripe forming method of the present invention. In this method, the longitudinal direction A of the contact portion between the scraping jig 30 and the translucent substrate sheet 10 is inclined with respect to the arrangement direction of the grooves 15. The scraping direction B of the tool 30 is the longitudinal direction of the groove 15. According to this method, the foreign matter 41 biting into the scraping jig 30 is inclined rearward with respect to the moving direction of the scraping jig 30 as the scraping jig 30 moves in the longitudinal direction of the groove 15. The force in the E direction is received. As a result, the foreign matter 41 is removed from the scraping jig 30 or loosened and moved obliquely rearward along the wall surface of the scraping jig 30, hits the wall of the groove 15, and is detached from the scraping jig 30. Therefore, even by this method, it is possible to obtain an optical sheet with improved appearance by suppressing the generation and growth of white lines.

  In this method, the angle θ2 between the longitudinal direction A of the contact portion between the scraping jig 30 and the translucent substrate sheet 10 and the direction in which the grooves 15 are arranged has a sufficient effect of the present invention. From the point that the jig 30 does not need to be long, the angle is preferably 3 to 60 °. In addition, the moving speed in the scraping direction B is preferably set to 1 to 20 m / min from the viewpoint of productivity and difficulty in scraping.

  In addition, it is only necessary to make the width of the scraping jig 30 slightly wider than the width in the arrangement direction of the grooves 15 of the translucent substrate sheet 10 according to the second stripe forming method. Since it is not necessary to form 30 broken lines or wavy lines, the device configuration required for scraping becomes simple.

  In the method for producing an optical sheet of the present invention, the light shielding material is scraped off by the first or second stripe forming method, and then the light shielding material in the groove is dried or cured according to a conventional method to obtain the optical sheet 1. Finalize.

  If necessary, the optical sheet 1 may be provided with an optical sheet, a colored sheet, an antiglare sheet, or the like in which light diffusing particles are dispersed on the light shielding part 21 side, the opposite side, or both.

  The optical sheet 1 obtained by the optical sheet manufacturing method of the present invention can be mounted on the front surface of a display panel 40 such as a plasma display or a liquid crystal display, or used as a rear projection screen. In this case, the direction in which the optical sheet is attached may be such that the prism row is directed to the viewer side or the image light source side in accordance with purposes such as improving external light contrast and viewing angle control. Moreover, the optical sheet 1 can be used as a diffusivity control sheet for a backlight such as a liquid crystal display.

Example 1
A translucent substrate sheet 10 having the cross-sectional shape of FIG. 2 was prepared by extrusion molding of a methyl methacrylate / styrene copolymer (MS resin).

In this case, the dimensions of the translucent substrate sheet 10 were as follows.

Prism 11 height L1: 157 μm
Groove width L2: 32 μm
Width L4 at the tip of the groove 15: 2 μm
Layer thickness L3 of the translucent substrate sheet 10: 300 μm
Width L5 of the upper surface 12 of the prism row: 74 μm
Pitch P: 106μm
Angle α of the slope 13 near the upper surface of the prism row 11 and the height direction of the prism row α: 3.85 °
Angle β with respect to the height direction of the inclined surface 13 and the prism row at a height substantially half of the prism row 11: 6.67 °
Curvature radius R of shoulder 14 of prism row 11: 13 μm

Next, black ink made of a urethane acrylate UV curable resin containing 3% by weight of carbon particles having an average particle diameter of 5 μm was applied to the entire surface of the translucent substrate sheet 10 on the side where the grooves 15 were arranged. And as shown in FIG. 7, with respect to the arrangement direction C of the grooves of the translucent substrate sheet 10, a rubber squeegee is disposed obliquely as the scraping jig 30, and the rubber squeegee is vibrated as follows. Under the conditions, excess black ink was scraped off continuously for 5 minutes.

Movement direction of translucent substrate sheet 10: parallel to longitudinal direction C of groove Translucent substrate sheet 10 moving speed: 3.6 m / min Squeegee rubber hardness (JIS K6031): 80 degrees Squeegee arrangement: relative to groove arrangement direction Angle θ2 = 5 °
Squeegee vibration pattern: Sine wave shape Squeegee vibration frequency: 60Hz
Squeegee vibration amplitude: ± 1mm

  After scraping off the black ink, the black ink filled in the groove was cured by irradiating with ultraviolet rays to produce a viewing angle control sheet.

  Also, the black ink was cured in the same manner for the translucent substrate sheet immediately after the start of scraping of the black ink (about 5 seconds), and a viewing angle control sheet was produced.

Comparative Example 1
A viewing angle control sheet was produced in the same manner as in Example 1 except that the squeegee arrangement was parallel to the groove arrangement direction and the squeegee was not vibrated.

Evaluation The viewing angle control sheets of Example 1 and Comparative Example 1 were held over a fluorescent lamp, and the occurrence of white lines was visually evaluated. The results are shown in Table 1.

  From Table 1, the viewing angle control sheet of Example 1 has a markedly reduced number of white lines and a significantly shorter length than the viewing angle control sheet of Comparative Example 1, and the appearance quality is greatly improved. It was done.

  INDUSTRIAL APPLICABILITY The present invention is useful as a technique for manufacturing optical sheets such as display and screen viewing angle control sheets, diffusion control sheets, and contrast improvement sheets.

It is a perspective view of an optical sheet. It is sectional drawing of an optical sheet. It is explanatory drawing of the formation method of a 1st stripe. It is explanatory drawing of a scraping direction. It is explanatory drawing of the deformation | transformation aspect of the formation method of a 1st stripe. It is explanatory drawing of the formation method of a 2nd stripe. It is explanatory drawing of the scraping-off method of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical sheet 10 Translucent base material sheet | seat 11 Prism row | line | column 12 Upper surface 13 of a prism row | line | slope 14 The slope part 14 of a prism row | line | column Shoulder | groove 20 Light-shielding stripe 21 Light-shielding part 30 Horizontal stripes L1 Height of light shield L2 Width of light shield L3 Layer thickness of translucent substrate sheet L4 Width of groove tip L5 Width of top surface of prism row A Scraping jig and translucent substrate Longitudinal direction of contact part with sheet B Relative moving direction of scraping jig (scraping direction)
C Longitudinal direction of groove D Moving direction of foreign matter E Moving direction of foreign matter P Pitch of light-shielding stripe

Claims (4)

Apply the filling material to the parallel surface of the groove of the base sheet with a plurality of grooves arranged on the surface, and scrape the filling material on the surface of the base sheet with a scraping jig so as to leave the filling material in the groove. A method of forming a stripe of filling material on a base sheet by scraping,
A method of forming a stripe, characterized in that the relative movement direction of the scraping jig with respect to the base sheet intersects the longitudinal direction of the groove. Apply the filling material to the parallel surface of the groove of the base sheet with a plurality of grooves arranged on the surface, and scrape the filling material on the surface of the base sheet with a scraping jig so as to leave the filling material in the groove. A method of forming a stripe of filling material on a base sheet by scraping,
The longitudinal direction of the contact portion of the scraping jig with respect to the base sheet is oblique to the arrangement direction of the grooves, and the relative movement direction of the scraping jig with respect to the base sheet is the longitudinal direction of the grooves. Stripe formation method. A light-shielding material is applied to the side-by-side surface of the light-transmitting base sheet having a plurality of grooves arranged in parallel on the surface, and the light-transmitting base sheet surface is left so that the light-shielding material remains in the grooves. A method for producing an optical sheet having a light-shielding stripe by scraping a light-shielding material with a scraping jig,
A method for producing an optical sheet, characterized in that the relative movement direction of the scraping jig with respect to the translucent substrate sheet intersects with the longitudinal direction of the groove. A light-shielding material is applied to the side-by-side surface of the light-transmitting base sheet having a plurality of grooves arranged in parallel on the surface, and the light-transmitting base sheet surface is left so that the light-shielding material remains in the grooves. A method for producing an optical sheet having a light-shielding stripe by scraping a light-shielding material with a scraping jig,
The longitudinal direction of the contact portion of the scraping jig with respect to the translucent substrate sheet is inclined with respect to the arrangement direction of the grooves, and the relative movement direction of the scraping jig with respect to the translucent substrate sheet is defined as the longitudinal direction of the grooves. A method for producing an optical sheet, comprising:

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