JP2008058494A - Manufacturing method of microlens array sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress presence of air bubbles in a microlens array sheet in a 2P molding method using a roll plate. <P>SOLUTION: An ionization radiation curing resin which is liquid and has viscosity of 100 to 500cP is applied onto the outer peripheral surface 30 of the rotating roll plate by using a dye coater 4 to form an ionization radiation curing resin film 11. A band-shaped base material film 10 is made to pass between a nip roll 2 and the roll plate where the ionization radiation curing resin film 11 is formed. At this time, the base material film 10 is pressed to a roll plate 3 side by the nip roll 2 and the ionization radiation curing resin film 11 is held between the base material film 10 and the roll plate 3. The held ionization radiation curing resin is cured by ionization radiation to form the microlens array sheet 14. Since viscosity of the ionization radiation curing resin is low and air bubbles hardly remain in the ionization radiation curing resin film 11, the presence of the air bubbles in the microlens array sheet 14 can be suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a microlens array sheet. More specifically, the present invention relates to a microlens array sheet that is manufactured by curing an ionizing radiation curable resin filled between a roll plate and a base film with ionizing radiation. The present invention relates to a method for manufacturing a lens array sheet.

  A display device represented by a liquid crystal display is required to have high front luminance. Therefore, an optical lens sheet for improving the front luminance is laid on the backlight device constituting the display device.

  One of optical lens sheets for a backlight device for improving the front luminance is a microlens array sheet. A backlight device using a microlens array sheet is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-145329 (Patent Document 1).

  The microlens array sheet has a sheet shape and has a plurality of convex lenses (microlenses) arranged two-dimensionally on one surface. A microlens sheet used in a backlight device collects and emits diffused light from a light source by a plurality of microlenses. Therefore, the front brightness is improved.

  By the way, as one method for producing an optical lens sheet, there is a 2P (Photo polymerization) molding method using a roll plate having a lens molding groove or hole on the outer peripheral surface. This manufacturing method is disclosed in, for example, Japanese Patent No. 3616109 (Patent Document 2). In this manufacturing method, a lens molding groove or hole formed on the outer peripheral surface of the roll plate is filled with an ionizing radiation curable resin. Subsequently, the base film is passed between the nip roll and the roll plate. At this time, the substrate film is brought into contact with the ionizing radiation curable resin on the outer peripheral surface of the roll plate by pressing the substrate film to the roll plate side with a nip roll. After the base film is brought into contact with the ionizing radiation curable resin, the ionizing radiation curable resin is cured by ionizing radiation to mold a plurality of lenses (prisms, microlenses, etc.). The optical lens sheet is manufactured through the above steps.

However, when a microlens array sheet is manufactured by this manufacturing method, bubbles are included in the manufactured microlens sheet. Bubbles in the microlens array sheet reduce the light collection effect. In addition, the presence of bubbles causes an appearance defect, which is not preferable for the product.
JP 2004-145329 A Patent No. 3616109

  The objective of this invention is providing the manufacturing method of the micro lens array sheet which can suppress that a bubble exists in a micro lens array sheet in 2P shaping | molding method using a roll plate.

Means for Solving the Problems and Effects of the Invention

  The method for producing a microlens array sheet according to the present invention includes a step of rotating a roll plate having an outer peripheral surface having a plurality of lens molding holes for molding a plurality of microlenses, and a nip roll arranged in parallel with the roll plate. And by applying a liquid ionizing radiation curable resin having a viscosity of 100 to 500 cP on the outer peripheral surface of the roll plate from above the rotating roll plate, filling the lens molding hole with the ionizing radiation curable resin, and A step of forming an ionizing radiation curable resin film on the surface, a step of passing a belt-like base film between the nip roll and the roll plate on which the ionizing radiation curable resin film is formed, and a nip roll and an ionizing radiation curable resin film are formed. By pressing the base film passing between the roll plate and the roll plate side with a nip roll, the base film and the outer peripheral surface of the roll plate The step of sandwiching the ionizing radiation curable resin film, and the ionizing radiation curable resin filled in the lens molding hole and the ionizing radiation curable resin film sandwiched between the base film and the outer peripheral surface of the roll plate by curing with ionizing radiation are cured. A process. Here, the ionizing radiation is, for example, ultraviolet rays or electron beams. The ionizing radiation curable resin is a resin that is cured by ionizing radiation.

  In the method for producing a microlens array sheet according to the present invention, an ionizing radiation curable resin having a viscosity of 100 to 500 cP, which is lower than that of a conventional ionizing radiation curable resin, is used. Since the ionizing radiation curable resin has a low viscosity, even if air bubbles enter the ionizing radiation curable resin, the air bubbles easily escape to the outside before the ionizing radiation curable resin is cured by the ionizing radiation. Therefore, bubbles are less likely to be present in the microlens array sheet.

  Preferably, in the step of sandwiching the ionizing radiation curable resin film, the ionizing radiation curable resin film cured by ionizing radiation is pressed with a nip roll so that the thickness of the ionizing radiation curable resin film is 5 μm or less, and the ionizing radiation cured Adjust the thickness of the resin film.

  When the base film is passed between the nip roll and the roll plate, the air bubbles are mainly caused by a part of the ionizing radiation curable resin film (liquid ionizing radiation curable resin) formed on the roll plate between the nip roll and the roll plate. It occurs by staying between. Therefore, the bubbles are more likely to enter the ionizing radiation curable resin film in contact with the base film, rather than the ionizing radiation curable resin filled in the lens molding hole. If the ionizing radiation curable resin film sandwiched between the base film and the roll plate is thinned, bubbles are less likely to enter. Specifically, it was manufactured by adjusting the thickness of the ionizing radiation curable resin film sandwiched between the base film and the roll plate so that the ionizing radiation curable resin film cured by ionizing radiation was 5 μm or less. Air bubbles are less likely to be present in the microlens array sheet.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  [Overall configuration of manufacturing equipment]

  First, a microlens array sheet manufacturing apparatus will be described.

  With reference to FIG.1 and FIG.2, the manufacturing apparatus 50 of a micro lens array sheet is the base film roll 1, the nip roll 2, the roll plate 3, the die coater 4, the peeling roll 5, and the winding roll 6. The exposure apparatus 7 and the ionizing radiation curable resin supply apparatus 8 are provided.

  The base film roll 1 has a strip-shaped base film 10 wound around the outer peripheral surface. The base film 10 is transparent with respect to the wavelength in the visible light region. The base film 10 transmits ionizing radiation such as ultraviolet rays and electron beams. The base film 10 is, for example, a polyester resin, a polycarbonate resin, a polyacrylate ester resin, an alicyclic polyolefin resin, a polystyrene resin, a polyvinyl chloride resin, a polyvinyl acetate resin, or a polyether sulfone. It is composed of a resin such as an acid resin or a triacetyl cellulose resin.

  The base film roll 1 rotates clockwise in FIG. 1 and unwinds the base film 10 wound on the outer peripheral surface. The unwound base film 10 is conveyed toward the roll plate 3.

  The die coater 4 is disposed above the roll plate 3. The die coater 4 receives the supply of the liquid ionizing radiation curable resin from the ionizing radiation curable resin supply device 8. The die coater 4 discharges a liquid ionizing radiation curable resin from a lip opening 41 provided on the lower surface and applies it to the outer peripheral surface 30 of the roll plate 3 that rotates counterclockwise in FIG.

  The nip roll 2 is juxtaposed with the roll plate 3. More specifically, the nip roll 2 is disposed in front of the roll plate 3 so that its own axis is parallel to the axis of the roll plate 3. The nip roll 2 rotates clockwise in FIG. 1 and winds the base film 10 conveyed from the base film roll 1 around the outer peripheral surface. The nip roll 2 further passes the base film 10 wound around the outer peripheral surface between the nip roll 2 and the roll plate 3 on which the ionizing radiation curable resin film 11 is formed.

  The nip roll 2 can be moved to the roll plate 3 side by a pressing device (not shown). The nip roll 2 moves to the roll plate 3 side, thereby pressing the base film 10 passing between the nip roll 2 and the roll plate 3 to the roll plate 3 side. As a result, the ionizing radiation curable resin film 11 is sandwiched between the base film 10 and the outer peripheral surface 30 of the roll plate.

  The nip roll 2 also forms a staying portion 12 above the point P1 where the distance between the nip roll 2 and the roll plate 3 is the shortest. The staying part 12 is formed by a part of the liquid ionizing radiation curable resin constituting the ionizing radiation curable resin film 11 staying on the point P1. The staying part 12 prevents the ionizing radiation curable resin sandwiched between the base film 10 that has passed the point P1 and the outer peripheral surface 30 of the roll plate from being insufficient.

  As shown in FIGS. 3 and 4, the roll plate 3 includes an outer peripheral surface 30 having a plurality of lens molding holes 31. The plurality of lens molding holes 31 correspond to the plurality of microlenses 13 that are two-dimensionally arranged on the microlens sheet 14. That is, as shown in FIG. 3, the plurality of lens molding holes 31 are two-dimensionally arranged on the outer peripheral surface 30 of the roll plate 3, and the surface 32 of each lens molding hole 31 is substantially spherical as shown in FIG. It is. The ionizing radiation curable resin applied to the outer peripheral surface 30 of the roll plate 3 by the die coater 4 is filled in each lens molding hole 31 and further has a predetermined thickness on the outer peripheral surface 30 of the roll plate 3. 11 is formed.

  Returning to FIG. 1, the exposure device 7 is disposed below the roll plate 3. The exposure device 7 irradiates ionizing radiation from the upper surface toward the roll plate 3. The ionizing radiation curable resin film 11 and the ionizing radiation curable resin filled in the lens molding hole 31 on the outer peripheral surface 30 of the roll plate 3 are cured by the ionizing radiation irradiated from the exposure device 7. Thereby, the microlens array sheet 14 is manufactured.

  The peeling roll 5 is arranged in parallel with the roll plate 3 on the upper and rear sides of the roll plate 3. The peeling roll 5 rotates clockwise in FIG. 1, whereby the microlens array sheet 14 wound around the roll plate 3 is peeled off from the roll plate 3. The peeled microlens array sheet 14 is conveyed to the take-up roll 6.

  The winding roll 6 rotates clockwise in FIG. 1 and winds the conveyed microlens array sheet 14 around the outer peripheral surface.

  [Production method of microlens array sheet]

  A method for manufacturing the microlens array sheet 14 using the manufacturing apparatus 50 described above will be described.

  First, a roll plate 3 having a plurality of lens molding holes 31 corresponding to a microlens array sheet having a desired size is prepared.

  Subsequently, an ionizing radiation curable resin discharged from the die coater 4 is prepared. In general, an ionizing radiation curable resin having a viscosity of 1000 cP (centipoise) or more at room temperature (25 ° C.) is used in an optical lens sheet manufactured by a 2P molding method. On the other hand, in the present embodiment, an ionizing radiation curable resin having a viscosity lower than that of the prior art, specifically, a viscosity of 100 to 500 cP at room temperature (25 ° C.) is prepared. When the viscosity of the ionizing radiation curable resin is less than 100 cP, the viscosity is too low and the resin tends to flow and is difficult to be fixed on the outer peripheral surface of the roll plate 3. Therefore, the ionizing radiation curable resin film 11 cannot be formed uniformly. On the other hand, if the viscosity of the ionizing radiation curable resin is higher than 500 cP, bubbles that have entered the ionizing radiation curable resin at the staying portion 12 are difficult to escape, and bubbles remain in the ionizing radiation curable resin film 11 that has passed through the point P1. It becomes easy. Therefore, the ionizing radiation curable resin has a viscosity of 100 to 500 cP.

  An ionizing radiation curable resin having a viscosity of 100 to 500 cP includes, for example, a main agent made of an acrylate resin having a viscosity of 1000 cP to 5000 cP, a diluent made of an acrylate resin having a viscosity of 10 to 20 cP, and a photoinitiator. Is done. Examples of the acrylate resin include urethane acrylate, epoxy acrylate, and polyacryl acrylate. If the above-mentioned main agent, diluent and photoinitiator are appropriately blended, the viscosity of the ionizing radiation curable resin can be made 100 to 500 cP. More preferably, the ionizing radiation curable resin has a main agent content of 80 to 85 wt%, a diluent content of 10 to 15 wt%, and a photoinitiator content of 5 wt% or less. . In addition, you may use the main ingredient and diluent which consist of resin different from acrylate-type resin.

  The viscosity of the ionizing radiation curable resin is, for example, the value of each ultraviolet curable resin measured at room temperature (25 ° C.) using a Visconic EMD viscosity measuring device manufactured by Tokyo Keiki Seisakusho.

  After preparing the ionizing radiation curable resin, the production of the microlens array sheet 14 is started. First, the base film roll 1, the nip roll 2, the peeling roll 5 and the take-up roll 6 are rotated clockwise in FIG. 1, and the roll plate 3 is rotated counterclockwise.

  At this time, a liquid ionizing radiation curable resin having a viscosity of 100 cP to 500 cP is applied from the die coater 4 to the outer peripheral surface of the roll plate 3. The applied ionizing radiation curable resin is filled into a plurality of lens molding holes 31 formed on the outer peripheral surface of the roll plate 3. Further, a liquid ionizing radiation curable resin film 11 having a predetermined thickness is formed on the outer peripheral surface 30 of the roll plate 3.

  By rotating the base film roll 1 clockwise, the base film 10 wound around the outer peripheral surface of the base film roll 1 is unwound and conveyed in the direction of the roll plate 3. The nip roll 2 conveys the base film 10 in the rotating direction of the nip roll while contacting the outer peripheral surface thereof.

  The base film 10 conveyed by the nip roll 2 is passed between the nip roll 2 and the roll plate 3 on which the ionizing radiation curable resin film 11 is formed. The ionizing radiation curable resin film 11 is sandwiched between the base film 10 and the outer peripheral surface of the roll plate 3.

  At this time, as shown in FIG. 2, the base film 10 is pressed to the roll plate 3 side by the nip roll 2, and the thickness T1 of the ionizing radiation curable resin film 11 at the point P1 is set upstream of the staying portion 12. The ionizing radiation curable resin film 11 is made smaller than the thickness T2. As a result, part of the ionizing radiation curable resin applied on the outer peripheral surface 30 of the roll plate 3 stays above the point P <b> 1, thereby forming the staying portion 12.

  The staying part 12 is necessary for stably forming the ionizing radiation curable resin film 11 downstream from the point P1. Without the staying part 12, the ionizing radiation curable resin sandwiched between the base film 10 and the outer peripheral surface 30 after the point P1 is insufficient, and a gap can be formed between the base film 10 and the outer peripheral surface 30. Because.

  However, in the staying part 12, air easily enters from the outside, and the invading air is not likely to be bubbles. Hereinafter, the mechanism by which bubbles are formed in the staying part 12 will be described. Of the liquid ionizing radiation curable resin constituting the staying part 12, the ionizing radiation curable resin in the vicinity of the outer peripheral surface of the nip roll 2 (that is, in the vicinity of the base film 10) is agitated by the rotation of the nip roll 2. At this time, air enters the stirred ionizing radiation curable resin from the outside, and bubbles are formed in the staying portion 12. When the bubbles in the staying portion 12 enter the ionizing radiation curable resin film 11 after the point P1, the ionizing radiation curable resin film 11 is cured while the bubbles are present, and the bubbles remain in the microlens array sheet 14.

  Therefore, it is considered that if bubbles are prevented from entering the ionizing radiation curable resin film 11 after the point P1, it is possible to suppress the bubbles from being contained in the manufactured microlens array sheet 14.

  In the present embodiment, in order to prevent bubbles from entering the ionizing radiation curable resin film 11 after the point P1, as described above, the viscosity of the ionizing radiation curable resin is set to 100 to 500 cP, which is lower than the conventional one. The reason why it is possible to suppress the presence of bubbles in the microlens array sheet 14 by setting the viscosity to 100 to 500 cP is not clear, but the following reason is presumed. When the ionizing radiation curable resin has a viscosity of 100 to 500 cP, even if air enters the retention part 12 to form bubbles, the bubbles do not stay below the retention part 12 because the viscosity is low. It tends to float upward. Since the bubbles hardly remain at the point P1 located below the staying portion 12, the bubbles are unlikely to enter the ionizing radiation curable resin film 11 that has passed through the point P1.

  Further, in the present embodiment, the base film 10 is pressed to the roll plate 3 side by the nip roll 2 so that the thickness of the ionizing radiation curable resin film 11 after being cured by the ionizing radiation is 5 μm or less. The thickness of the ionizing radiation curable resin film at P1 is adjusted. Since the thickness of the ionizing radiation curable resin film is substantially the same before and after curing, the thickness T1 of the ionizing radiation curable resin film 11 at the point P1 is set to 5 μm or less. The following reasons are presumed as the reason why bubbles can be suppressed from being contained in the microlens array sheet 14 by setting the thickness to 5 μm or less.

  As described above, bubbles are mainly generated in the staying portion 12. Therefore, if the distance L0 between the nip roll 2 and the outer peripheral surface 30 of the roll plate 3 at the point P1 below the staying part 12 is large, bubbles generated at the staying part 12 can easily pass through the contact point P1. In order to prevent the passage of bubbles, it is preferable to shorten the distance L0.

  If the ionizing radiation curable resin having a viscosity of 100 to 500 cP described above is used, and the thickness T1 of the ionizing radiation curable resin sandwiched between the base film 10 and the outer peripheral surface 30 is 5 μm or less, the distance L0 is short. Therefore, bubbles are less likely to enter the ionizing radiation curable resin film 11 after the point P1. Therefore, it is considered that bubbles can be suppressed from being contained in the microlens array sheet 14.

  The base film 10 that has passed through the point P <b> 1 and the ionizing radiation curable resin 11 that has come into contact with the base film 10 rotate counterclockwise along the outer peripheral surface of the roll plate 3. Below the roll plate 3, ionizing radiation is irradiated from the exposure device 7 toward the outer peripheral surface 30. At this time, the ionizing radiation passes through the base film 10 and reaches the ionizing radiation curable resin filled in the ionizing radiation curable resin film 11 and the lens molding hole 31. Therefore, the ionizing radiation curable resin filled in the ionizing radiation curable resin film 11 and the lens molding hole 31 is cured by the ionizing radiation. Thereby, the microlens array sheet 14 is formed. As shown in FIGS. 5 and 6, the microlens array sheet 14 includes a base film 10 and a lens layer 20 formed on the base film 10 and having a plurality of microlenses 13 on the surface. . The thickness T3 of the lens layer 20, that is, the distance from the flat portion 22 on the lens surface 21 to the surface 23 opposite to the lens surface 21, is substantially equal to the thickness T1 of the ionizing radiation curable resin film 11 before curing. The same. Accordingly, the thickness T3 is 5 μm or less.

  The formed microlens array sheet 14 is conveyed toward the peeling roll 5 while being wound around the roll plate 3. The microlens array sheet 14 is peeled off from the roll plate 3 with the peeling roll 5. The peeled microlens array sheet 14 is conveyed to the take-up roll 6 and taken up on the outer peripheral surface of the take-up roll 6. The microlens array sheet 14 can be manufactured by the above process.

  In the manufacturing method according to the present embodiment, by setting the viscosity of the ionizing radiation curable resin to 100 cP to 500 cP, it is possible to prevent bubbles generated in the staying portion 12 from entering the ionizing radiation curable resin film 11 passing through the point P1. it can. Therefore, it is difficult for bubbles to be inherent in the microlens array sheet 14.

  Furthermore, in the manufacturing method according to the present embodiment, the base film 10 passing through the point P1 is pressed against the roll plate 3 side by the nip roll 2, and the thickness of the ionizing radiation curable resin film after curing is 5 μm or less. The thickness of the ionizing radiation curable resin film 11 passing through the point P1 is adjusted. Thereby, it is possible to prevent bubbles generated in the staying portion 12 from entering the ionizing radiation curable resin film 11. Therefore, it is difficult for bubbles to be inherent in the microlens array sheet 14.

  Note that it is considered that the smaller the thickness of the ionizing radiation curable resin film 11 passing through the point P1, the more the bubbles can be prevented from entering. However, if the ionizing radiation curable resin film 11 is not formed, the lens molding hole 31 is formed after the point P1. There is a case where the ionizing radiation curable resin filled in is insufficient. Therefore, the ionizing radiation curable resin film 11 after the point P1 needs to have a certain thickness. The lower limit of the thickness of the preferable ionizing radiation curable resin film is 1 μm. However, even if the thickness is less than the lower limit, the effect of the present invention can be obtained to some extent.

  In addition, the preferable conveyance speed of the base film 10 at the time of manufacture is 3-20 m / min. If the conveying speed is too slow, the ionizing radiation curable resin having the above viscosity tends to spread in the axial direction of the outer peripheral surface 30 of the roll plate 3, and the ionizing radiation curable resin on the outer peripheral surface 30 may leak from the roll end of the roll plate 3. Occurs. On the other hand, if the conveying speed is too fast, the ionizing radiation curable resin film 11 cannot be stably formed. If the conveyance speed is 3 to 20 m / min, the ionizing radiation curable resin film 11 can be stably formed without the ultraviolet curable resin leaking from the end of the roll. Note that the effect of the present invention can be obtained to some extent even when the conveyance speed is out of the above-described preferable range.

  In the present embodiment, the convex surface of the microlens 13 on the microlens array sheet 14 is a spherical surface, but the convex shape of the microlens 13 is not limited to a spherical surface. For example, the cross-sectional shape of the convex surface of the microlens may be an elliptical arc shape. In this case, the cross-sectional shape of the lens molding hole of the roll plate is also an elliptical arc. Further, the microlens may have another shape.

  In the microlens array sheet 14 manufactured in the present embodiment, the preferable curvature radius R13 of the convex surface of each microlens 13 is 5 to 100 μm. The preferred height H13 of the microlens 13 (that is, the height from the top of the microlens 13 to the flat portion 22) is 5 to 100 μm. Preferably, a distance (lens pitch) LP between lens vertices of adjacent microlenses is 8 to 202 μm. Preferably, as shown in FIG. 5, the ratio of the occupation area of the plurality of microlenses 14 to the total area of the microlens array sheet 14 when the microlens array sheet 14 is viewed from directly above (hereinafter, the lens occupation ratio). Is 70-90%. However, the effect of the present invention can be obtained to some extent even with a microlens array sheet having a different size and lens occupancy.

  A microlens array sheet was manufactured by a 2P method using a roll plate using ultraviolet curing resins having a plurality of types of viscosity. The manufactured microlens array sheet was examined for the presence of bubbles.

  [Production method]

  An acrylate resin having various viscosities and a photoinitiator were appropriately blended to prepare UV curable resins having viscosities of 200 cP, 300 cP, 400 cP, 500 cP, 700 cP, 1000 cP, and 1500 cP at room temperature (25 ° C.), respectively. The viscosity of each ultraviolet curable resin was measured using a Visconic EMD viscosity measuring device manufactured by Tokyo Keiki Seisakusho.

  A microlens array sheet was produced for each ultraviolet curable resin using the produced ultraviolet curable resin and the production apparatus shown in FIG.

  A polyethylene terephthalate (PET) film having a thickness of 200 μm was used as the base film. Moreover, the conveyance speed was 5 m / min and the test was performed at room temperature (25 ° C.). The thickness of the cured ultraviolet curable resin (that is, the thickness T3 of the lens layer) was 3 μm.

  Of the manufactured microlens array sheet, the curvature radius of the convex surface of each microlens was 20 μm, the height of the microlens was 20 μm, and the lens pitch was 45 μm. The lens occupation ratio was 86%.

  [Investigation method]

  About each manufactured microlens array sheet | seat, the presence or absence of the bubble was investigated with the following method.

  With reference to FIG. 7, in each manufactured microlens array sheet, the presence or absence of bubbles was examined at an arbitrary place having a length of 1 m. A center portion (hereinafter, referred to as a center line) CL of a 1-meter-long microlens array sheet, and locations (hereinafter, referred to as side lines) SLL and SLR at a position of ± 45 mm in the width direction from the center of the width. Were visually observed with a 500 × microscope to examine the presence or absence of bubbles. When one or more bubbles were confirmed in the center line CL and the side lines SLL and SLR visually observed, it was determined that bubbles were contained in the microlens array sheet. In the center line CL and the side lines SLL and SLR, when bubbles could not be confirmed, it was determined that no bubbles were contained in the microlens sheet.

  [Investigation result]

  The survey results are shown in FIG. The horizontal axis in FIG. 8 indicates the viscosity (cP) of the used ultraviolet curable resin. In addition, the “O” mark on the vertical axis indicates that the manufactured microlens sheet is determined not to contain bubbles, and the “X” mark indicates that the microlens sheet is determined to contain bubbles. Indicates.

  Referring to FIG. 8, the microlens array sheet using an ultraviolet curable resin having a viscosity of 500 cP or less contained no bubbles. On the other hand, the microlens array sheet using the ultraviolet curable resin having a viscosity of 700 cP, 1000 cP, and 1500 cP contained bubbles.

  A plurality of microlens array sheets with different thicknesses of the ultraviolet curable resin film at the time of manufacture were manufactured, and the presence or absence of bubbles inside was investigated.

  [Manufacturing method and survey method]

  Similarly to Example 1, a plurality of microlens array sheets having the same lens dimensions and lens occupation ratio as those of Example 1 were manufactured using the manufacturing apparatus shown in FIG. The pressing force applied to the base film by the nip roll was adjusted during production, and the thickness T3 of the lens layer of the microlens array sheet after production was changed for each microlens array sheet in the range of 2 μm to 10 μm.

  The test was conducted at room temperature (25 ° C.). Moreover, the ultraviolet curable resin used for the test was composed of an acrylate resin and a photoinitiator, and its viscosity was set to 300 cP. The conveyance speed of the base film was 5 m / min. Other conditions were the same as in Example 1.

  About each manufactured micro lens array sheet | seat, the presence or absence of a bubble was investigated with the same investigation method as Example 1. FIG.

  [Investigation result]

  The survey results are shown in FIG. The horizontal axis in the figure indicates the thickness (μm) of the ultraviolet curable resin film (lens layer). The vertical axis is the same as in FIG.

  Referring to FIG. 9, the microlens array sheet having a lens layer thickness T3 of 5 μm or less contained no bubbles. On the other hand, the microlens array sheet in which the lens layer thickness T3 exceeded 5 μm contained bubbles.

  While the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

It is the schematic which shows the whole structure of the manufacturing apparatus of the micro lens array sheet by embodiment of this invention. FIG. 2 is an enlarged view of the vicinity of a nip roll and a roll plate in FIG. 1. FIG. 2 is a development view of a part of the outer peripheral surface of the roll plate in FIG. 1. It is sectional drawing in line segment IV-IV in FIG. It is a top view of the micro lens array sheet manufactured by this Embodiment. It is sectional drawing in line segment VI-VI in FIG. It is a figure for demonstrating the investigation method of the presence or absence of the bubble in a micro lens array sheet. It is a figure which shows the investigation result of Example 1. FIG. It is a figure which shows the investigation result of Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base film roll 2 Nip roll 3 Roll plate 7 Exposure apparatus 10 Base film 11 Ionizing radiation hardening resin film 13 Micro lens 14 Micro lens array sheet 31 Lens molding hole

Claims (2)

A step of rotating a roll plate having an outer peripheral surface having a plurality of lens molding holes for molding a plurality of microlenses, and a nip roll arranged in parallel to the roll plate;
By applying a liquid ionizing radiation curable resin having a viscosity of 100 to 500 cP from above the rotating roll plate to the outer peripheral surface of the roll plate, filling the lens molding hole with the ionizing radiation curable resin, and Forming an ionizing radiation curable resin film on the outer peripheral surface;
Passing a strip-shaped base film between the nip roll and the roll plate on which the ionizing radiation curable resin film is formed;
The base film passing between the nip roll and the roll plate on which the ionizing radiation curable resin film is formed is pressed against the roll plate side by the nip roll, and the base film and the outer peripheral surface of the roll plate And sandwiching the ionizing radiation curable resin film with,
A step of curing the ionizing radiation curable resin film sandwiched between the base film and the outer peripheral surface of the roll plate and the ionizing radiation curable resin filled in the lens molding hole by irradiating with ionizing radiation; A method of manufacturing a microlens array sheet, comprising: It is a manufacturing method of the micro lens array sheet according to claim 1,
In the step of sandwiching the ionizing radiation curable resin film, the ionized radiation curable resin film cured by the ionizing radiation is pressed with the nip roll so that the thickness of the ionizing radiation curable resin film is 5 μm or less, and the ionized radiation is sandwiched. A method for producing a microlens array sheet, comprising adjusting a thickness of a radiation curable resin film.

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