Method for producing laminated body

Abstract

The present invention provides a method for manufacturing a laminated body and a bonding device that can easily control the amount and direction of warping of a laminated body having an optical display panel and an optical film after bonding. The method for manufacturing a laminated body (300) having an optical display panel (100) and an optical film (200) comprises a pressing step of pressing the laminated body (300) of the optical display panel (100) and the optical film (200) between a pair of rotating nip rollers (21, 22), and in the pressing step, the laminated body (300) is given warping in a manner along the surface of one nip roller (21).

Description

Technical Field

[0001] The present invention relates to a method for producing a laminated body used in an optical display device such as a liquid crystal display and a bonding device. Background Art

[0002] Conventionally, an operation of obtaining a laminated body by bonding an optical film such as a polarizing plate to an optical display panel such as a liquid crystal panel has been performed.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-137538

[0006] However, for example, in an optical display panel such as a liquid crystal panel, warping may occur in the laminate after lamination due to residual stress of the optical display panel and the optical film during lamination, shrinkage / expansion of the optical film over time, etc. This tendency becomes more significant as the optical display panel becomes larger. As a method for eliminating the above-mentioned warping problem, there is a method of preliminarily giving the optical display panel a slight warping in the direction opposite to the warping direction. Summary of the invention

[0007] Problems to be solved by the invention

[0008] An object of the present invention is to provide a method for producing a laminate and a bonding apparatus that can easily control the amount and direction of warping of a laminate having an optical display panel and an optical film after bonding.

[0009] Solutions to Solve Problems

[0010] The method of the present invention is a method for producing a laminated body, wherein the laminated body has an optical display panel and an optical film, wherein:

[0011] The method for manufacturing a laminate comprises a pressing step of pressing a laminate of an optical display panel and an optical film between a pair of rotating nip rollers.

[0012] In the pressing step, the laminate is warped so as to follow the surface of one of the nip rolls.

[0013] Here, the method may further include:

[0014] A step of conveying the optical display panel toward the pair of nip rollers by using an upstream horizontal conveying mechanism; and

[0015] a step of conveying the stacked body discharged from the pair of nip rollers by a downstream horizontal conveying mechanism,

[0016] The rotation axes of the pair of nip rollers are arranged separately in the up-down direction.

[0017] In the pressing step, the height of the portion of the stack sandwiched by the pair of rollers is made lower or higher than the height of the upper surface of the upstream horizontal conveying mechanism and the height of the upper surface of the downstream horizontal conveying mechanism, thereby imparting warping to the stack.

[0018] Furthermore, in the above method, the warping may not be imparted to the stacked body until the front end portion of the stacked body in the moving direction reaches above the downstream horizontal conveying mechanism,

[0019] After the front end of the stack in the moving direction reaches above the downstream horizontal conveying mechanism, the warping is imparted to the stack,

[0020] The warping is eliminated while the rear end portion of the optical display panel in the moving direction is supported by the upper surface of the upstream horizontal transport mechanism.

[0021] Alternatively, in the above method, the upstream horizontal conveying mechanism and the downstream horizontal conveying mechanism may be roller conveyors respectively.

[0022] Alternatively, the diameter of one of the nip rollers may be larger than the diameter of the other nip roller.

[0023] Furthermore, the optical film may be a polarizing plate, and in the laminated body pressed between the nip rollers, the transmission axis of the polarizing plate may be arranged in parallel with the rotation axis of the pair of nip rollers.

[0024] Furthermore, the surface of the optical display panel may have a rectangular shape, and in the laminate pressed between the nip rollers, the transmission axis of the polarizing plate may be arranged in parallel with the short side direction of the surface of the optical display panel.

[0025] Alternatively, the optical display panel may be a liquid crystal panel, and the polarizing plate may be bonded to the liquid crystal panel in such a manner that the transmission axis of the polarizing plate is substantially parallel to the short side direction of the liquid crystal panel. Alternatively, the polarizing plate may be bonded to the TFT side of the liquid crystal panel.

[0026] The bonding apparatus of the present invention includes: a pair of nip rollers for pressing a laminate of an optical display panel and an optical film; and a warp imparting mechanism for imparting warp to the laminate along a surface of one of the nip rollers.

[0027] Here, the rotation axes of the pair of nip rollers may be arranged separately in the up-down direction.

[0028] The warping imparting mechanism has:

[0029] an upstream horizontal conveying mechanism for conveying the optical display panel to the pair of nip rollers;

[0030] a downstream horizontal conveying mechanism that conveys the laminate of the optical display panel and the optical film discharged from the pair of nip rollers; and

[0031] A positioning mechanism that determines the position of the pair of clamping rollers so that the height of the portion of the stack clamped by the pair of clamping rollers is lower or higher than the height of the stack conveyed by the upstream horizontal conveying mechanism and the height of the stack conveyed by the downstream horizontal conveying mechanism.

[0032] Alternatively, the device may further include a control unit, which controls the positioning mechanism so that:

[0033] Before the front end of the stack in the moving direction reaches above the downstream horizontal conveying mechanism, the height of the portion of the stack sandwiched by the pair of nip rollers is maintained at the same height as the upper surface of the upstream horizontal conveying mechanism and the upper surface of the downstream horizontal conveying mechanism;

[0034] After the front end of the stacked body in the moving direction reaches above the downstream horizontal conveying mechanism, the position of the pair of clamping rollers is changed relative to the upstream horizontal conveying mechanism and the downstream horizontal conveying mechanism so that the height of the portion of the stacked body clamped by the pair of clamping rollers is lower or higher than the height of the upper surface of the upstream horizontal conveying mechanism and the height of the upper surface of the downstream horizontal conveying mechanism;

[0035] While the rear end portion of the optical display panel in the moving direction is supported by the upper surface of the upstream horizontal conveying mechanism, the height of the portion of the stack clamped by the pair of clamping rollers is returned to the same height as the upper surface of the upstream horizontal conveying mechanism and the upper surface of the downstream horizontal conveying mechanism.

[0036] Alternatively, the upstream horizontal conveying mechanism and the downstream horizontal conveying mechanism may be roller conveyors respectively.

[0037] Furthermore, the diameter of one of the nip rollers may be larger than the diameter of the other nip roller.

[0038] Furthermore, the optical film may be a polarizing plate, and in the laminated body pressed between the nip rollers, the transmission axis of the polarizing plate may be arranged in parallel with the axes of the pair of nip rollers.

[0039] Furthermore, the surface of the optical display panel may have a rectangular shape, and in the laminate pressed between the nip rollers, the transmission axis of the polarizing plate may be arranged in parallel with the short side direction of the surface of the optical display panel.

[0040] Furthermore, the optical display panel may be a liquid crystal panel, and the polarizing plate may be attached to a TFT side of the liquid crystal panel.

[0041] Effects of the Invention

[0042] According to the present invention, there are provided a method for producing a laminate and a bonding apparatus capable of easily controlling the amount and direction of warping of a laminate having an optical display panel and an optical film after bonding. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 (a) is a schematic diagram showing a cross-sectional structure of a liquid crystal panel (optical display panel) according to an embodiment of the present invention, Figure 1 (b) is a schematic diagram showing a cross-sectional structure of a polarizing plate (optical film) according to one embodiment of the present invention.

[0044] Figure 2 It is a schematic diagram of the bonding apparatus according to one embodiment of the present invention.

[0045] Figure 3 is a schematic diagram of a bonding device according to an embodiment of the present invention, and is a diagram showing the bonding device according to an embodiment of the present invention. Figure 2 state diagram.

[0046] Figure 4 1 is a diagram showing the relationship between the length L in the conveyance direction of the liquid crystal panel and H1 ′.

[0047] Figure 5 (a) to (c) are schematic end views of the laminated bodies of various forms after bonding, as viewed from the short side direction (horizontal direction is the long side direction).

[0048] Figure 6 1 is a schematic diagram showing an outline of a fixed warpage amount of an embodiment, Figure 6 (a) shows the amount of warpage before fixation, Figure 6 (b) shows the warpage amount after fixation.

[0049] Description of Reference Numerals

[0050] 1 Laminating device, 5 Warp imparting mechanism, 10 Upstream roller conveyor (upstream horizontal conveying mechanism), 21, 22 Nip rollers, 21a, 22a Rotating axes, 100 Liquid crystal panel (optical display panel), 200 Polarizing plate (optical film), 300 Laminated body, 40 Downstream roller conveyor (downstream horizontal conveying mechanism), 50 Positioning mechanism, 60 Control section, P section, S Horizontal plane, A Front short side, B Rear short side, 400A Front fixed warp amount, 400B Rear fixed warp amount. DETAILED DESCRIPTION

[0051] One embodiment of the present invention will be described with reference to the accompanying drawings. It should be noted that the dimensions of the drawings are arbitrary for the purpose of describing the invention.

[0052] In this embodiment, a case where a liquid crystal panel is used as an optical display panel and a polarizing plate is used as an optical film is selected as an example to explain a method and an apparatus for bonding the liquid crystal panel and the polarizing plate. Figure 1 (a) and Figure 1 (b) The target liquid crystal panel 100 and polarizing plate 200 are described.

[0053] like Figure 1 As shown in (a), the liquid crystal panel 100 may include a first transparent substrate 100A, a liquid crystal layer 100B, and a second transparent substrate 100C in this order. In the case of a liquid crystal panel, the material of the first transparent substrate and the second transparent substrate may be typically glass.

[0054] In this embodiment, the shape of the liquid crystal panel 100 is a rectangle.

[0055] The size of the rectangle of the liquid crystal panel 100 is not particularly limited, but the long side may be 20 to 2600 mm. In particular, since a larger liquid crystal panel tends to be more susceptible to warping, the long side is preferably 1200 mm or more.

[0056] The thickness of the liquid crystal panel 100 is not particularly limited, and may be, for example, about 0.5 to 5 mm, and preferably 1 to 5 mm.

[0057] like Figure 1 As shown in (b), the polarizing plate 200 may include: a pair of protective films 200A and 200C; a polarizer layer 200B disposed between the pair of protective films 200A and 200C; and a binder / adhesive layer 200D disposed on one of the protective films 200C.

[0058] Examples of the protective films 200A and 200C include films commonly used in the technical field of polarizing plates, such as triacetyl cellulose films (hereinafter sometimes referred to as "TAC"), cycloolefin films, and acrylic films. Figure 1 (b) shows a cross-sectional structure of a polarizer having protective films 200A and 200B provided on both sides of a polarizer layer 200B, but a polarizer having a protective film provided on only one side of a polarizer layer (single-side protected polarizer) may also be applied to the present invention. Although not shown, in the case of a single-side protected polarizer, an adhesive / adhesive layer 200D is usually provided directly on the side of the polarizer layer 200B without the protective film.

[0059] The polarizer forming the polarizer layer 200B may be a polyvinyl alcohol film dyed with a dichroic dye such as iodine, and may be produced by uniaxial stretching. Hereinafter, such a polyvinyl alcohol film dyed with a dichroic dye such as iodine may be referred to as "PVA".

[0060] The adhesive / adhesive layer 200D may be, for example, an acrylic resin layer.

[0061] The thickness of the polarizing plate 200 is not particularly limited, and may be, for example, 25 to 200 μm.

[0062] In the present embodiment, the polarizing plate 200 is attached to one surface of the liquid crystal panel 100 via a pressure-sensitive adhesive layer 200D of the polarizing plate 200 .

[0063] Figure 2 Schematic diagram of a laminating device 1 according to a first embodiment of the present invention. The laminating device 1 according to this embodiment mainly comprises: an upstream roller conveyor 10; a pair of nip rollers 21 and 22; a downstream roller conveyor 40; a positioning mechanism 50 for adjusting the height of the pair of nip rollers 21 and 22; and a control unit 60 for controlling the positioning mechanism 50. The laminating device 1 manufactures a laminate 300 by laminating a liquid crystal panel 100 and a polarizing plate 200. The pair of nip rollers 21 and 22, the upstream roller conveyor 10, the downstream roller conveyor 40, and the positioning mechanism 50 constitute a warping imparting mechanism 5.

[0064] The upstream roller conveyor (upstream horizontal conveying mechanism) 10 includes a plurality of conveying rollers 10a, each of which has a rotation axis arranged in the horizontal direction and arranged parallel to each other in the horizontal plane. The upstream roller conveyor 10 conveys the liquid crystal panel 100 supplied from a supply source (not shown) on the upper surface of the upstream roller conveyor in the horizontal direction (in the horizontal direction). Figure 2 The material is transported (from left to right in the figure) and supplied between a pair of nip rollers 21 and 22.

[0065] In this embodiment, the upstream roller conveyor 10 conveys the liquid crystal panel 100 with both rectangular surfaces oriented in the vertical direction and with the short sides of the rectangular surfaces of the liquid crystal panel 100 parallel to the axes of the nip rollers 21 and 22 .

[0066] The nip rollers 21 and 22 have rotation axes 21a and 22a, respectively. The rotation axes 21a and 22a are arranged to be separated in the up-down direction, and the rotation axes 21a and 22a are arranged to be parallel to each other and to the rotation axis of the conveying roller 10a of the upstream roller conveyor 10. The material of the surface of the nip roller is not particularly limited, and rubber, metal, etc. can be applied, but rubber is preferably used from the aspect of not significantly damaging the liquid crystal panel.

[0067] In this embodiment, the diameter of the upper nip roller 21 is larger than the diameter of the lower nip roller 22. Therefore, it is preferable that the stacked body 300 can be appropriately warped along the upper nip roller 21 having a larger diameter, while the stacked body 300 can be sufficiently pressed using the lower nip roller 22 having a smaller diameter.

[0068] The diameter of the upper nip roller 21 may be 30 to 300 mm. In addition, the diameter of the lower nip roller 22 may be 10 to 100 mm.

[0069] Since the stacked body 300 is Figure 1 The upstream side (left side) is transported to the downstream side (right side), so the upper clamping roller 21 can be Figure 1 The middle nip roller 22 moves counterclockwise, and the lower nip roller 22 moves clockwise. A pair of nip rollers can be either a driving roller or a driven roller, and preferably at least one is a driving roller.

[0070] The polarizer 200 is supplied from the polarizer roller 30 to the lower nip roller 22. In the present embodiment, the transmission axis of the polarizer 200 is arranged in parallel with the rotation axis of the nip rollers 21 and 22. That is, the absorption axis of the polarizer is in parallel with the conveying direction of the liquid crystal panel. Between the nip rollers 21 and 22, the polarizer 200 is attached to the liquid crystal panel 100 to obtain a laminated body 300 including them, and the laminated body 300 is discharged to the downstream side.

[0071] It should be noted that the polarizer 200 is supported on the separator 210 to protect the adhesive / adhesive layer, and is conveyed by the lower nip roller 22 in a state where only the polarizer 200 is half-cut to match the size of the liquid crystal panel 100, and the separator 210 is recovered by the reel 80 after the polarizer is attached. By using the separator 210 in this way, foreign matter and the like can be prevented from being attached to the adhesive / adhesive layer of the polarizer 200.

[0072] Although not shown in the figure, a pressure imparting mechanism is provided on the pair of nip rollers 21 and 22 so that one nip roller presses the other nip roller at a predetermined pressure. Thus, the laminated body 300 supplied between the pair of nip rollers 21 and 22 can be sandwiched from both sides in the thickness direction, and the liquid crystal panel 100 and the polarizing plate 200 can be pressed to make the liquid crystal panel 100 and the polarizing plate 200 closely attached.

[0073] The pressing pressure can be appropriately set according to the required warping amount of the laminate 300 , the characteristics of the liquid crystal panel 100 , the characteristics of the polarizing plate 200 , etc., and can be, for example, 0.1 to 0.7 MPa.

[0074] The downstream roller conveyor (downstream horizontal conveying mechanism) 40 includes a plurality of conveying rollers 40a, each of which has a rotation axis arranged in the horizontal direction and arranged parallel to each other in the horizontal plane. Figure 2 The stacked body 300 discharged from the pair of nip rollers 21 and 22 is transported (from left to right in the figure). The obtained stacked body 300 is provided to the assembly process of the liquid crystal display at the subsequent stage.

[0075] The positioning mechanism 50 can move the position of the pair of clamping rollers 21 and 22 in the vertical direction. Figure 2 As shown in FIG. 1 , the positioning mechanism 50 can make the height H1 of the portion P of the stacked body 300 sandwiched between the pair of nip rollers 21 and 22 the same height as the height H2 of the upper surface of the upstream roller conveyor 10 and the height H3 of the upper surface of the downstream roller conveyor 40. Usually, the height H2 is the same as the height H3. It should be noted that the positioning mechanism 50 may be in a form in which one of the nip rollers 21 and 22 is positioned and the other nip roller slides along the one nip roller, or may be in a form in which the positioning of the two nip rollers 21 and 22 is controlled.

[0076] Furthermore, the positioning mechanism 50 may be Figure 3 As shown, a height H1 of a portion P of the stacked body 300 sandwiched between the pair of nip rollers 21 and 22 is set lower than a height H2 of the upper surface of the upstream roller conveyor 10 and a height H3 of the upper surface of the downstream roller conveyor 40 .

[0077] When the value of height H1 when height H1 is lower than height H2 and height H3 is set to H1min, H1min is preferably 1 mm or more lower than height H2 and height H3, more preferably 2 mm or more lower, and further preferably 3 mm or more lower. The upper limit of the height difference is not particularly limited, and may be, for example, 10 mm or less.

[0078] Here, the height H2 of the upper surface of the upstream roller conveyor 10 may be replaced by the height of the lower surface of the liquid crystal panel 100 horizontally conveyed by the upstream roller conveyor 10, and the height H3 of the upper surface of the downstream roller conveyor 40 may be replaced by the height of the lower surface of the stacked body 300 horizontally conveyed by the downstream roller conveyor 40. In addition, the height H1 of the portion P of the stacked body 300 sandwiched between the pair of nip rollers 21 and 22 is the height of the lowest portion within the bottom surface of the portion P of the stacked body 300 sandwiched between the pair of nip rollers 21 and 22.

[0079] There are no particular limitations on the distance CV1 in the conveying direction between the rotation axes 21a, 22a of the pair of nip rollers 21, 22 and the rotation axis of the roller 10a1 closest to the nip rollers 21, 22 of the upstream roller conveyor 10, and the distance CV2 in the conveying direction between the rotation axes 21a, 22a of the pair of nip rollers 21, 22 and the rotation axis of the roller 40a1 closest to the nip rollers 21, 22 of the downstream roller conveyor 40, but they are preferably about 2 to 5 times the diameter of the roller on the larger diameter side of the pair of nip rollers 21, 22. In addition, the length of the liquid crystal panel 100 in the conveying direction (for example, the length of the long side) exceeds CV1+CV2, and is usually twice or more.

[0080] The control unit 60 controls the positioning mechanism 50 to move the pair of nip rollers 21 and 22 up and down, thereby changing the height H1 of the portion P of the stacked body 300 sandwiched between the pair of nip rollers 21 and 22. Specifically, in the present embodiment, the control unit 60 changes the height H1 of the portion P up and down when a single liquid crystal panel 100 passes between the pair of nip rollers 21 and 22.

[0081] Specifically, the control unit 60 can Figure 4 The height H1 is changed as shown. The horizontal axis is the length in the conveying direction of the liquid crystal panel 100 (for example, the long side direction or short side direction of the rectangle), the length L=0 is the end at the side where the lamination starts (the front side in the conveying direction), and the length Lmax is the end at the side where the lamination ends (the rear end side in the conveying direction). The height H1 of the vertical axis is the height H1 of the portion P of the laminate 300 sandwiched between the pair of rollers 21 and 22, based on the height H2 of the upper surface of the upstream roller conveyor 10 and the height H3 of the upper surface of the downstream roller conveyor 40. The negative sign means that it is lower than the heights H2 and H3.

[0082] The height H1 is maintained at 0 from length 0 (the bonding start position) to length L1, decreases from length L1 to length L2, is maintained at a height H1min lower than heights H2 and H3 from length L2 to length L3, increases from length L3 to length L4, and is maintained at 0 from length L4 to length Lmax (the bonding end position). In the present embodiment, Lmax corresponds to the length of the long side of the liquid crystal panel.

[0083] It can be that L1 is 10~500mm, L2-L1 is 100~2500mm, Lmax-L4 is 10~500mm, and L4-L3 is 10~500mm.

[0084] The height H1min is preferably the above-mentioned value.

[0085] In other words, the control unit 60 controls the positioning mechanism 50 so that before the front end F of the stack 300 formed between the pair of clamping rollers 21 and 22 contacts the upper surface (or a portion) of the downstream roller conveyor 40, the height H1 of the portion P of the stack 300 clamped by the pair of clamping rollers is maintained at the same height as the height H2 of the upper surface of the upstream roller conveyor 10 and the height H3 of the upper surface of the downstream roller conveyor 40.

[0086] In addition, the control unit 60 controls the positioning mechanism 50 so that after the front end F of the stack 300 contacts the upper surface (a portion thereof) of the downstream roller conveyor 40, while the rear end R of the stack 300 contacts the upper surface (a portion thereof) of the upstream roller conveyor 10, the height H1 of the portion P of the stack 300 clamped by the pair of clamping rollers is lower than the height H2 of the upper surface of the upstream roller conveyor 10 and the height H3 of the upper surface of the downstream roller conveyor 40.

[0087] Furthermore, the control unit 60 controls the positioning mechanism 50 so that when the front end F of the stack 300 is in contact with the upper surface (a portion thereof) of the downstream roller conveyor 40 and the rear end R of the stack 300 is in contact with the upper surface (a portion thereof) of the upstream roller conveyor, the height of the portion P of the stack 300 clamped by the pair of clamping rollers is returned to the same height as the height H2 of the upper surface of the upstream roller conveyor 10 and the height H3 of the upper surface of the downstream roller conveyor 40, and thereafter, the stack 300 is maintained at the same height until it is discharged from between the pair of clamping rollers.

[0088] It should be noted that the timing of the height change of the control unit 60 can be achieved by detecting the front end F and the rear end R of the conveyed liquid crystal panel 100 using appropriate sensors or by recognizing the speed of the conveyance line.

[0089] Next, a method for manufacturing an optical display device according to an embodiment of the present invention will be described.

[0090] First, if Figure 2 As shown, the liquid crystal panel 100 is fed between a pair of nip rollers 21 and 22 by the upstream roller conveyor 10, and the polarizing plate 200 fed from the polarizing plate roller 30 is fed between the pair of nip rollers 21 and 22 along the surface of the lower nip roller 22, and the laminate 300 of the liquid crystal panel 100 and the polarizing plate 200 is pressed by the pair of nip rollers 21 and 22. Thus, the liquid crystal panel 100 is in contact with the adhesive / adhesive layer 200D of the polarizing plate 200, and the bonding is completed sequentially from the front end F to the rear end R.

[0091] Here, the control unit 60 controls the positioning mechanism 50 so as not to give warping to the stacked body 300, so that the height H1 of the portion P of the stacked body 300 sandwiched by the pair of nip rollers 21 and 22 is equal to the height H2 of the upper surface of the upstream roller conveyor 10 and the height H3 of the upper surface of the downstream roller conveyor 40 before the front end F of the stacked body 300 in the moving direction reaches the upper surface of the downstream roller conveyor 40. Thus, damage to the front end F of the stacked body 300 is suppressed.

[0092] After that, the conveyance of the stack 300 is advanced, and when the front end F in the moving direction of the stack 300 reaches above the downstream roller conveyor 40, the control unit 60 controls the positioning mechanism 50 so that the portion P of the stack 300 is lower than the height H2 of the upper surface of the upstream roller conveyor 10 and the height H3 of the upper surface of the downstream roller conveyor 40. Thus, the stack 300 is given a warp along the upper nip roller 21, and the liquid crystal panel 100 and the polarizing plate 200 are attached by the pair of nip rollers 21 and 22 in a state in which the warp is given.

[0093] Thereafter, when the conveyance of the stacked body 300 is further advanced, in a state where the rear end R of the liquid crystal panel 100 in the moving direction is supported by the upper surface of the upstream roller conveyor 10, the control unit 60 controls the positioning mechanism 50 to eliminate the warping so that the height of the portion P of the stacked body 300 sandwiched by the pair of nip rollers 21 and 22 returns to the same height as the upper surface of the upstream roller conveyor 10 and the upper surface of the downstream roller conveyor 40. Thus, damage to the rear end R of the stacked body 300 is suppressed.

[0094] In this way, the liquid crystal panel 100 and the polarizing plate 200 are bonded together in a warped state, thereby completing the formation of the laminated body 300 .

[0095] Next, a backlight or the like may be incorporated into the laminate 300 as necessary, thereby obtaining a liquid crystal display (optical display device).

[0096] Next, the operation of this embodiment will be described.

[0097] In the manufacture of liquid crystal displays, polarizing plates are attached to both sides of the liquid crystal panel, and the transmission axes of the two polarizing plates are arranged perpendicular to each other (orthogonal polarization). In addition, the polarizer of the polarizing plate is usually manufactured by stretching, so the polarizing plate is easy to shrink in the direction perpendicular to the transmission axis, that is, in the direction parallel to the absorption axis.

[0098] In this embodiment, the transmission axis of the polarizing plate 200 is parallel to the rotation axes 21a and 22a between the pair of nip rollers 21 and 22, that is, in a direction orthogonal to the conveying direction of the laminate 300. Figure 2 In the process, the liquid crystal panel 100 and the polarizing plate 200 are attached between a pair of nip rollers 21 and 22 while maintaining a state without warping.

[0099] In particular, if the liquid crystal panel 100 is bonded to the polarizing plate 200 in such a manner that the short side direction of the liquid crystal panel 100 is parallel to the transmission axis of the polarizing plate 200, in other words, in such a manner that the long side direction of the liquid crystal panel 100 is parallel to the absorption axis of the polarizing plate 200, then after bonding, the polarizing plate 200 shrinks along the absorption axis direction, so that the laminated body 300 after bonding is easy to be formed. Figure 5 As shown in (a), the surface (lower surface) of the polarizing plate 200 is warped so that the surface (lower surface) of the liquid crystal panel 100 becomes concave and the surface (the upper surface opposite to the bonding surface of the polarizing plate 200) of the liquid crystal panel 100 becomes convex. Figure 5 In (a) to (c), the horizontal direction is the longitudinal direction of the stacked body 300 and the liquid crystal panel 100. If such warping exists, it may cause problems such as light leakage in a liquid crystal display after being combined with a backlight, so it is sometimes required to reduce the amount of warping.

[0100] In particular, in Figure 5 When the polarizing plate 200 having an absorption axis parallel to the long-side direction is attached to the TFT side surface 100 of the liquid crystal panel 100 as shown in (b), it is not preferable to Figure 5 As in (a), the color filter side surface 100CF of the liquid crystal panel 100 is made convex, although it is also preferable to Figure 5 There is no warping as in (b), but sometimes it is preferred to Figure 5 (c) warps in the opposite direction.

[0101] According to this embodiment, when the laminated body 300 is pressed between a pair of nip rollers, as shown in FIG. Figure 3In this way, the laminate 300 is warped along the surface of one of the nip rollers 21. That is, the laminate is pressed and bonded while the surface (lower surface) of the polarizing plate 200 is made convex and the surface (upper surface) of the liquid crystal panel 100 opposite to the bonding surface of the polarizing plate is made concave. In this way, the stress between the liquid crystal panel 100 and the polarizing plate 200 of the laminate 300 can be controlled, and the shape of the laminate 300 after bonding can be prevented from becoming Figure 5 (a) and make the direction of the warping Figure 5 (a) is the same as (a) and reduces warpage, or Figure 5 (b) to form a shape without warping, or Figure 5 The reverse warping is given as in (c).

[0102] The warpage of the laminated body 300 after pasting can be controlled specifically by Figure 3 The amount of warping of the laminate 300 in the pressing process between the pair of nip rollers 21 and 22 is adjusted. For example, as H1min is made lower than H2 and H3 to increase the warping, it can be sequentially transformed into Figure 5 (a) the state of Figure 5 (b) and Figure 5 (c) Such a state.

[0103] The present invention is not limited to the above-described embodiment, and various modifications are possible.

[0104] For example, the rotation axes 21a and 22a of the pair of rollers 21 and 22 do not need to be parallel to the short side direction of the rectangle of the liquid crystal panel 100 during pasting, but may be parallel to the long side direction of the rectangle, or may be inclined to the long side direction or the short side direction of the rectangle.

[0105] In addition, in the above embodiment, the transmission axis of the polarizer 200 during pasting is parallel to the rotation axes 21a, 22a of a pair of clamping rollers 21, 22, but the direction of the transmission axis is arbitrary, and can also be perpendicular to the rotation axes 21a, 22a of a pair of clamping rollers 21, 22, and can also be implemented in an inclined direction.

[0106] In addition, as the horizontal conveying mechanism, for example, a belt conveyor or the like may be used other than the roller conveyor.

[0107] In addition, in the above embodiment, if Figure 4 As shown, a scheme is provided in which the height H1 is the same as the height H2 and H3 when the stack is not supported by both the upstream roller conveyor and the downstream roller conveyor. However, when the difference between H1 and H2 and H3 is small, it is possible to implement it even if H1 is fixed in a state different from H2 and H3.

[0108] In the above embodiment, the case where the polarizing plate is attached to the TFT side of the liquid crystal panel is described. However, the present invention can also be applied to a case where the polarizing plate is attached to the color filter side of the liquid crystal panel.

[0109] In addition, the shape of the liquid crystal panel does not need to be rectangular, and may be various shapes such as circular or elliptical.

[0110] Furthermore, in the above-mentioned embodiment, the pre-cut laminate is attached to the long supporting film, and the polarizing plate is supplied by pressing the liquid crystal panel and the polarizing plate together with the supporting film, but it can also be supplied by other methods. For example, the laminate cut by a blade or the like can be attached to the polarizing plate after being peeled off from the supporting film, and then supplied between a pair of nip rollers.

[0111] In addition, as long as the polarizing plate includes a polarizer layer, the stacked structure is not particularly limited.

[0112] In addition, the above embodiment uses a liquid crystal panel as an optical display panel, but it can also be applied to optical display panels other than liquid crystal panels, such as organic EL panels, etc. The thickness, shape, and size of the optical display panel other than the liquid crystal panel can be the same as that of the liquid crystal panel.

[0113] The organic EL panel may include a first transparent substrate, an organic light emitting diode (OLED) layer, and a second transparent substrate. The first transparent substrate may be a substrate with TFTs.

[0114] In addition, the optical film attached to the optical display panel is not limited to the linear polarizer, and can also be applied to various films such as circular polarizer obtained by laminating a phase difference plate on a polarizer, elliptical polarizer, phase difference plate, brightness enhancement film, birefringence control film, and anti-reflection film. Even if the optical film itself exhibits anisotropic shrinkage behavior, the warping after attachment can be controlled by imparting warping during attachment.

[0115] Furthermore, in the above-mentioned embodiment, a warping imparting mechanism 5 having an upstream roller conveyor 10, a downstream roller conveyor 40, a pair of clamping rollers 21, 22, and a positioning mechanism 50 for a pair of clamping rollers is used to impart warping by moving the pair of clamping rollers 21, 22 downward, but the method of imparting warping to the stacked body in a manner along the surfaces of the pair of clamping rollers is not limited to this.

[0116] For example, even in the pressing process, it is possible to make the height of the portion P of the stack 300 clamped by the pair of clamping rollers 21 and 22 higher than the height H2 of the upper surface of the upstream roller conveyor 10 and the height H3 of the upper surface of the downstream roller conveyor 40, and utilize gravity to move the portion P of the stack 300 along the lower clamping roller 22.

[0117] Furthermore, the present invention can be implemented even when the optical display panel is conveyed not horizontally but obliquely.

[0118] In addition, in the above-mentioned embodiment, the diameters of the pair of nip rollers 21 and 22 are different from each other, but the embodiment can be implemented even if they have the same diameters. It should be noted that, when the height H1 of the portion P is moved to a position lower than the heights H2 and H3 to impart warping, it is preferred that the diameter of the upper nip roller is larger, and when the height H1 of the portion P is moved to a position higher than the heights H2 and H3 to impart warping, it is preferred that the diameter of the lower nip roller is larger.

[0119] Furthermore, instead of the horizontal conveying mechanism including a plurality of rollers as in the upstream roller conveyor 10 and the downstream roller conveyor 40 , a single roller may be disposed before and after the pair of nip rollers 21 and 22 to impart warping.

[0120] [Example]

[0121] (Examples 1 to 6 and Comparative Example 1)

[0122] use Figure 2 as well as Figure 3 The bonding device shown bonds the liquid crystal panel to the polarizing plate.

[0123] LCD panel: Thickness is 1.0mm, the long side of the rectangle is 1660mm, and the short side is 950mm.

[0124] The laminated structure of the polarizing plate: adhesive layer (thickness: 20 μm) / TAC (thickness: 60 μm) / PVA (thickness: 20 μm) / TAC (thickness: 60 μm).

[0125] In addition, although TAC and PVA are bonded together via an adhesive layer, the description of the thickness of the adhesive layer is omitted.

[0126] The transmission axis of the polarizing plate is arranged parallel to the rotation axis of the nip roller, and the short side of the liquid crystal panel is arranged parallel to the rotation axis of the nip roller. The polarizing plate is attached to the TFT side of the liquid crystal panel.

[0127] Conditions of the nip rolls: The diameter of the upper nip roll was 100 mm, and the diameter of the lower nip roll was 30 mm. It should be noted that the nip rolls used were rubber rolls.

[0128] Table 1 shows CV1, CV2, the bonding pressure by the pair of nip rollers, the bonding speed ratio, and the presence or absence of the pair of nip rollers being lowered during bonding and the amount of the lowering.

[0129] It should be noted that the bonding speed ratio refers to the speed ratio of the liquid crystal panel 100 to the speed of the polarizing plate 200 .

[0130] In addition, regarding the decrease in the height H1 during the bonding process, Figure 4 It is set as L1=250mm, L2=350mm, L3=1240mm, L4=1340mm.

[0131] The warpage amount of the obtained laminated body is shown in Table 1. Figure 6 As shown in (a), the laminate 300 is placed on a horizontal plane S with the warped convex side facing downward, and the maximum warping amount of the bonded rear short side B on the bottom surface is measured as the front fixed warping amount 400A in a state where the bonded front short side A on the bottom surface of the laminate 300 is in contact with the horizontal plane S. Figure 6 As shown in (b), the maximum warping amount of the bonded front short side A on the bottom surface is measured as the rear fixing warping amount 400B in a state where the bonded rear short side B on the bottom surface is in contact with the horizontal plane S. Figure 5 The warpage when the color filter side surface 100CF of the liquid crystal panel 100 is convex as in (a) is regarded as positive warpage. Figure 5 The case where the TFT side surface of the liquid crystal panel 100 is warped so that the TFT is convex as in (c) is defined as negative warping.

[0132] [Table 1]

[0133]

[0134] According to the Examples, it was confirmed that the amount and direction of the warping of the laminated body can be controlled.

Claims

1. A method for manufacturing a laminate, the laminate comprising an optical display panel and an optical film, wherein: The method for manufacturing a laminate comprises a pressing step of pressing a laminate of an optical display panel and an optical film between a pair of rotating nip rollers. In the pressing step, the laminate is warped so as to follow the surface of one of the nip rolls.

2. The method for producing a laminate according to claim 1, wherein: The method for manufacturing the laminate further comprises: A step of conveying the optical display panel toward the pair of nip rollers by using an upstream horizontal conveying mechanism; and a step of conveying the stacked body discharged from the pair of nip rollers by a downstream horizontal conveying mechanism, The rotation axes of the pair of nip rollers are arranged separately in the up-down direction. In the pressing step, the height of the portion of the stack sandwiched by the pair of rollers is made lower or higher than the height of the upper surface of the upstream horizontal conveying mechanism and the height of the upper surface of the downstream horizontal conveying mechanism, thereby imparting warping to the stack.

3. The method for producing a laminate according to claim 2, wherein: The warping is not imparted to the stacked body until the front end portion of the stacked body in the moving direction reaches above the downstream horizontal conveying mechanism, After the front end of the stack in the moving direction reaches above the downstream horizontal conveying mechanism, the warping is imparted to the stack, The warping is eliminated while the rear end portion of the optical display panel in the moving direction is supported by the upper surface of the upstream horizontal transport mechanism.

4. The method for producing a laminate according to claim 2 or 3, wherein: The upstream horizontal conveying mechanism and the downstream horizontal conveying mechanism are respectively roller conveyors.

5. The method for producing a laminate according to claim 1 or 2, wherein: The diameter of one of the nip rollers is larger than the diameter of the other nip roller.

6. The method for producing a laminate according to claim 1 or 2, wherein: The optical film is a polarizing plate, and in the laminated body pressed between the nip rollers, the transmission axis of the polarizing plate is arranged in parallel with the axes of the pair of nip rollers.

7. The method for producing a laminate according to claim 6, wherein: The surface of the optical display panel has a rectangular shape, and in the laminate pressed between the nip rollers, the transmission axis of the polarizing plate is arranged in parallel with the short-side direction of the surface of the optical display panel.

8. The method for producing a laminate according to claim 6, wherein: The optical display panel is a liquid crystal panel, and the polarizing plate is attached to the TFT side of the liquid crystal panel.

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