Method for manufacturing a polarizing plate

Abstract

To provide a method for manufacturing a polarizer piece, capable of preventing a dent from being generated in a polarizer to manufacture the polarizer piece excellent in appearance.SOLUTION: A method for manufacturing a polarizer piece comprises the steps of: bonding a long-sized surface protection film having a plurality of first through holes to a long-sized polarizer to form a laminate; subjecting parts of the polarizer exposed from the plurality of first through holes to decolorization to form a plurality of non-polarization parts; winding the laminate including the polarizer having the plurality of non-polarization parts in a roll state; and cutting a plurality of polarizer pieces including the non-polarization part from the polarizer. The surface protection film includes a second through hole positioned between a first through hole positioned at one end in the width direction in the plurality of first through holes and one end edge of the surface protection film in the width direction.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a polarizer sheet.

Background Art

[0002] In recent years, due to the rapid spread of smartphones and touch panel type information processing devices, further improvement in camera performance and the like has been desired. In addition, in order to cope with diversification and high functionality of the shape of image display devices, a polarizing plate having partial polarization performance has been demanded. As such a polarizing plate, a polarizer in which a non-polarizing portion is formed by chemical treatment is known. As a method for manufacturing a polarizing plate having a non-polarizing portion, after bonding a surface protection film having a plurality of through holes to a long polarizer intermediate, the portion of the polarizer intermediate exposed from the through holes is chemically decolorized to form a non-polarizing portion, and then, The laminate including the surface protection film / polarizer intermediate is wound into a roll, and then, it has been proposed to cut a plurality of polarizers including the non-polarizing portion from the polarizer intermediate (for example, Patent Document 1). However, when the laminate including the surface protection film having a plurality of through holes is wound into a roll, indentations (hole marks) may occur in the polarizer intermediate due to winding tightness.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been made to solve the above conventional problems, and its main object is to provide a method for manufacturing a polarizer sheet that can suppress the occurrence of indentations in the polarizer even when a laminate including a surface protection film having a plurality of first through holes is wound into a roll, and can manufacture a polarizer sheet with excellent appearance.

Means for Solving the Problems

[0005] A method for manufacturing a polarizer piece according to an embodiment of the present invention includes the steps of: bonding a long-sized surface protective film having a plurality of first through holes spaced apart in a width direction perpendicular to the long-sized direction of the surface protective film to a long-sized polarizer having a dichroic material to form a laminate; bleaching a portion of the polarizer exposed from the plurality of first through holes through the first through holes to form a plurality of non-polarized portions in the polarizer; winding up the laminate including the polarizer having the plurality of non-polarized portions formed therein into a roll; and cutting out a plurality of polarizer pieces including the non-polarized portions from the polarizer after the winding, wherein the surface protective film further has a first through hole located at one end of the plurality of first through holes in the width direction and a second through hole located between one edge of the surface protective film in the width direction. In one embodiment, the opening areas of the plurality of first through holes are substantially the same as each other, and the opening area of ​​the second through hole is 0.5 or more of the opening area of ​​each of the first through holes. In one embodiment, the opening areas of the plurality of first through holes are substantially the same as each other, and the opening area of ​​the second through hole is 0. 5 not and the second through holes are arranged at intervals in the longitudinal direction. In one embodiment, the surface protection film further has a third through hole located between a first through hole located at the other end of the plurality of first through holes in the width direction and the other edge of the surface protection film in the width direction. In one embodiment, the widthwise spacing between a first through hole located at one end of the width direction and the second through hole, and the widthwise spacing between the second through hole and one edge of the surface protective film are each less than or equal to the widthwise spacing between adjacent first through holes among the plurality of first through holes. Effect of the Invention

[0006] According to an embodiment of the present invention, it is possible to suppress the local increase in the roll hardness (internal roll stress) of the laminate wound in a roll shape and the occurrence of indentations on the polarizer, and to manufacture a polarizer sheet with excellent appearance.

Brief Description of the Drawings

[0007]

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Embodiments for Carrying Out the Invention

[0008] Hereinafter, representative embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0009] A. Outline of the method for manufacturing a polarizing film FIG. 1 is a schematic diagram showing one embodiment of the method for manufacturing a polarizing film of the present invention; FIG. 2 is a schematic perspective view of the surface protection film of FIG. 1; FIG. 3 is a schematic cross-sectional view in a direction parallel to the width direction of the laminate of FIG. 1; FIG. 4 is a schematic cross-sectional view of the state where the first surface protection film is removed from the laminate of FIG. 3; FIG. 5 is an enlarged plan view of the main part of the laminate of FIG. 3.

[0010] The method for manufacturing the polarizing film in the illustrated example includes a step of forming a laminate 4 by bonding a long surface protection film 1 having a plurality of first through-holes 1a to a long polarizer 21 having a dichroic substance (laminate forming step); a step of decolorizing the portion of the polarizer 21 exposed from the plurality of first through-holes 1a through the first through-holes 1a to form a plurality of non-polarizing portions 21a on the polarizer 21 (polarizer decolorizing step); a step of winding the laminate 4 including the polarizer 21 having the plurality of non-polarizing portions 21a in a roll shape (laminate winding step); and a step of cutting out a plurality of polarizing films 210 including the non-polarizing portions 21a from the polarizer 21 after winding (polarizing film cutting step). The surface protection film 1 has one end edge E1 and the other end edge E2 in the width direction orthogonal to the longitudinal direction. The plurality of first through-holes 1a are arranged at intervals in the width direction of the surface protection film 1. The surface protection film 1 further has a second through-hole 1b located between the first through-hole 1a located at one end in the width direction among the plurality of first through-holes 1a and one end edge E1 in the width direction of the surface protection film 1. After bonding the surface protection film having a plurality of through-holes to the polarizer and then winding the obtained laminate in a roll shape, due to winding tightness, the hardness (roll internal stress) of the roll of the laminate may become locally high. In particular, the end portion of the roll of the laminate is likely to have concentrated roll internal stress and is likely to have high hardness. In this case, there is a possibility that the polarizer may be scratched at the portion where the stress in the roll of the laminate is concentrated (specifically, the end portion, etc.). On the other hand, according to the method as described above, the surface protection film 1 is used for the plurality of decolorizing treatments ofIn addition to the first through-hole 1a, there is a second through-hole 1b located between the first through-hole 1a positioned at one end in the width direction and one end edge E1 of the surface protection film 1. Therefore, it is possible to suppress the concentration of the roll internal stress at one end of the roll 5 of the laminate 4, and it is possible to suppress the local increase in the hardness (roll internal stress) of the roll 5 of the laminate 4. In other words, it is possible to improve the uniformity of the hardness (roll internal stress) in the roll 5. As a result, it is possible to suppress the occurrence of scratches on the polarizer 21 included in the roll 5 of the laminate 4, and a plurality of polarizer pieces 210 having a non-polarizing portion 21a and excellent in appearance can be cut out from the polarizer 21.

[0011] The dimension of the laminate 4 in the width direction is typically 500 mm to 2000 mm, preferably 1000 mm to 1500 mm. The planar shape of the first through-hole 1a can be appropriately changed according to the shape required for the non-polarizing portion 21a. Examples of the planar shape of the first through-hole 1a include a circular shape, an elliptical shape, a square shape, a rectangular shape, a diamond shape, etc., and preferably a circular shape. The planar shape of the second through-hole 1b is not particularly limited. Examples of the planar shape of the second through-hole 1b include a circular shape, an elliptical shape, a square shape, a rectangular shape, a diamond shape, etc., and preferably a circular shape.

[0012] In one embodiment of the present invention, in the step of cutting out the polarizer piece, a plurality of polarizer pieces 210 having substantially the same configuration are cut out from the film of one polarizer 21. In this embodiment, the plurality of first through-holes 1a provided in the surface protection film 1 are arranged at substantially equal intervals from each other in the width direction, and the opening areas of each of the plurality of first through-holes 1a are substantially the same as each other. In the step of cutting out the polarizer piece, a plurality of two or more types of polarizer pieces 210 having substantially different configurations from each other may be cut out from the film of one polarizer 21. In this case, the plurality of first through-holes 1a may be arranged at different intervals from each other in the width direction, and the opening areas of each of the plurality of first through-holes 1a may be different from each other.

[0013] In one embodiment of the present invention, the surface protection film 1 has a plurality of rows 1A each consisting of a plurality of first through holes 1a arranged at substantially equal intervals in the width direction, with the rows 1A spaced apart in the longitudinal direction of the surface protection film 1. In this case, in the step of performing a decolorization process through the polarizer 21, a plurality of rows each consisting of a plurality of non-polarizing portions 21a arranged at equal intervals in the width direction can be formed in the polarizer 21 with intervals in the longitudinal direction of the polarizer 21. Therefore, it is possible to increase the number of polarizer pieces 210 that can be cut out from the long polarizer 21, and it is possible to improve the manufacturing efficiency of the polarizer pieces 210. The longitudinal interval between adjacent rows 1A is typically 10 mm to 500 mm, preferably 20 mm to 400 mm.

[0014] One second through hole 1b may be provided for one row 1A, or a plurality of second through holes 1b may be provided for one row 1A. When one second through hole 1b is provided for one row 1A, the second through hole 1b may be positioned so as to overlap a virtual line passing through the plurality of first through holes 1a included in the row 1A in the width direction, as shown in FIGS. 5 to 7, or may be arranged offset in the longitudinal direction from the virtual line, as shown in FIG. 8.

[0015] When one second through-hole 1b is provided for one column 1A, the opening area of the second through-hole 1b is, for example, 0.1 or more, preferably 0.5 or more, more preferably 1.0 or more, still more preferably 1.5 or more, and for example, 5.0 or less, preferably 3.0 or less, with respect to the opening area of each first through-hole 1a. Note that the opening area of the through-hole (first through-hole 1a or second through-hole 1b) is the area of the through-hole in the cross-section when the surface protection film 1 is cut in a plane direction orthogonal to the thickness direction. When the opening area of the second through-hole 1b with respect to each first through-hole 1a (the opening area of one second through-hole 1b / the opening area of one first through-hole 1a; hereinafter referred to as the opening area ratio of the second through-hole 1b) is not less than the above lower limit, particularly 0.5 or more, it is possible to stably suppress the local increase in the hardness (roll internal stress) of the roll 5 of the laminate 4. When the opening area ratio of the second through-hole 1b is not more than the above upper limit, the space for providing the second through-hole 1b in the surface protection film 1 can be reduced, and thus the margin portion located outside the product (polarizer sheet 210) of the polarizer 21 can be reduced.

[0016] Also, as shown in FIG. 9, when a plurality of second through-holes 1b are provided for one column 1A, even if the opening area ratio of the second through-holes 1b is less than 0.5, it is possible to stably suppress the local increase in the hardness (roll internal stress) of the roll 5 of the laminate 4. The plurality of second through-holes 1b are arranged at intervals in the longitudinal direction of the surface protection film 1. The number of second through-holes 1b provided for one column 1A is, for example, 2 to 10, preferably 2 to 8. In this case, the opening area ratio of the second through-holes 1b is preferably less than 0.5, more preferably 0.3 or less, still more preferably 0.2 or less, and for example, 0.01 or more, preferably 0.5 or less. If the opening area ratio of the second through-holes 1b is within the above range, it is possible to stably suppress the local increase in the hardness (roll internal stress) of the roll 5 of the laminate 4 while reducing the margin portion outside the product of the polarizer 21.

[0017] In one embodiment of the present invention, among the plurality of first through-holes 1a, the widthwise interval L2 between the first through-hole 1a located at one end in the width direction and the second through-hole 1b, and the widthwise interval L3 between the second through-hole 1b and one end edge E1 of the surface protection film 1 are each not more than the widthwise interval L1 between adjacent first through-holes 1a among the plurality of first through-holes 1a. The widthwise interval L1 between adjacent first through-holes 1a is typically 10 mm to 400 mm, preferably 20 mm to 300 mm. If the interval L4 between the first through-hole 1a located at one end in the width direction among the plurality of first through-holes 1a and one end edge E1 of the surface protection film 1 is not less than the interval L1 between adjacent first through-holes 1a, the balance of the positions of the plurality of first through-holes 1a deteriorates, and the uniformity of the positions of the plurality of first through-holes 1a decreases. Therefore, the roll internal stress tends to concentrate at one end of the roll 5 of the laminate 4. On the other hand, when the second through-hole 1b is provided so as to satisfy the above intervals L2 and L3, the plurality of first through-holes 1a and the second through-hole 1b are arranged in a well-balanced manner, so that the concentration of the roll internal stress at one end of the roll 5 of the laminate 4 can be stably suppressed.

[0018] In one embodiment of the present invention, as shown in FIGS. 8 and 10, the surface protection film 1 further has a third through-hole 1c located between the first through-hole 1a located at the other end in the width direction among the plurality of first through-holes 1a and the other end edge E2 in the width direction of the surface protection film 1. When the surface protection film 1 has the third through-hole 1c, it is possible to suppress the concentration of the roll internal stress at the other end of the roll 5 of the laminate 4, and it is possible to more stably suppress the local increase in the hardness (roll internal stress) of the roll 5 of the laminate 4. When the surface protection film 1 has a plurality of rows 1A composed of the plurality of first through-holes 1a spaced apart in the longitudinal direction, the third through-hole 1c may be provided one for each row 1A, as in the case of the second through-hole 1b, or a plurality may be provided for each row 1A.

[0019] Hereinafter, with reference to FIGS. 1 to 5, the details of the method for manufacturing a polarizer piece will be described. In one embodiment of the present invention, a surface protection film 1 is bonded to a polarizing plate 2 including a polarizer 21 and a protective layer 22 to form a laminate 4 (laminate forming step). Next, the polarizer 21 is partially decolorized to form a plurality of non-polarizing portions 21a (polarizer decolorizing step). After the laminate 4 is wound into a roll (laminate winding step), a plurality of polarizing plate pieces 20 each including a polarizer piece 210 including the non-polarizing portion 21a are cut out from the polarizer 21 (polarizing plate piece cutting step). In such an embodiment, a polarizing plate 2 with the protective layer 22 pre-attached to the polarizer 21 is prepared, but the timing of providing the protective layer 22 is not particularly limited. The surface protection film 1 may be bonded to the polarizer 21 without the protective layer 22 attached, and the protective layer 22 may be attached to the polarizer 21 after partial decolorization of the polarizer 21 and before winding of the laminate 4, or the protective layer 22 may be attached to the polarizer 21 after winding of the laminate 4 and before cutting out of the polarizing plate piece 20, or a protective layer piece 220 may be attached to each polarizer piece 210 after cutting out the polarizer piece 210 from the polarizer 21.

[0020] B. Laminate Forming Step In the laminate forming step, more specifically, after the second surface protection film 3 is bonded to the protective layer 22 provided in the polarizing plate 2 by roll-to-roll, the above-described surface protection film 1 is bonded to the polarizer 21 provided in the polarizing plate 2 by roll-to-roll to form the laminate 4. "Roll-to-roll" means bonding while aligning the longitudinal directions of each other while conveying a roll-shaped film. Hereinafter, the surface protection film 1 is distinguished as the first surface protection film 1 from the second surface protection film 3. By bonding the second surface protection film 3 to the polarizing plate 2 prior to the first surface protection film 1, it is possible to suppress the first through-hole 1a of the first surface protection film 1 from being transferred to the polarizer 21 as an indentation.

[0021] The laminate 4 has a laminated structure of a first surface protection film 1 / a polarizer 21 / a protective layer 22 / a second surface protection film 3. Note that after laminating the first surface protection film 1 to the polarizer 21, the second surface protection film 3 can also be laminated to the protective layer 22, and the first surface protection film 1 can be laminated to the polarizer 21 without using the second surface protection film 3.

[0022] B-1. Polarizing plate The polarizing plate 2 has a long shape and is typically rollable. The polarizing plate 2 includes a polarizer 21 and a protective layer 22 that is bonded via an arbitrary appropriate adhesive layer (adhesive layer, pressure-sensitive adhesive layer: not shown).

[0023] B-1-1. Polarizer As the polarizer 21, any appropriate polarizer can be adopted. For example, the resin film forming the polarizer 21 may be a single-layer resin film or a laminate of two or more layers. The resin film forming the polarizer 21 contains a dichroic substance. Examples of the dichroic substance include iodine, organic dyes, etc. The dichroic substances can be used alone or in combination. Among the dichroic substances, preferably, iodine is mentioned. For example, when forming the non-polarizing portion 21a by chemical decolorization treatment, the iodine complex contained in the polarizer 21 can be appropriately reduced, and for example, appropriate characteristics can be imparted to the non-polarizing portion 21a when used in the camera portion.

[0024] As a specific example of a polarizer composed of a single-layer resin film, there can be mentioned one obtained by subjecting a PVA-based resin film to a dyeing treatment with iodine and a stretching treatment (typically, uniaxial stretching). The above-mentioned dyeing with iodine is carried out, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio of the above uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment, or may be carried out while dyeing. Also, it may be dyed after stretching. If necessary, the PVA-based resin film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, etc. For example, by immersing the PVA-based resin film in water and washing it before dyeing, not only can the dirt and the blocking inhibitor on the surface of the PVA-based film be washed away, but also the PVA-based resin film can be swollen to prevent uneven dyeing and the like.

[0025] Specific examples of the polarizer obtained using the laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. The polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying it to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In one embodiment of the present invention, preferably, a PVA-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Further, stretching may further include, if necessary, stretching the laminate in air at a high temperature (for example, 95 °C or higher) before stretching in the aqueous boric acid solution. In addition, in one embodiment of the present invention, preferably, the laminate is subjected to a drying shrinkage treatment in which it is heated while being conveyed in the longitudinal direction to shrink by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an air-assisted stretching treatment, a dyeing treatment, a stretching treatment in water, and a drying shrinkage treatment in this order. By introducing the auxiliary stretching, even when PVA is applied on a thermoplastic resin, it becomes possible to enhance the crystallinity of PVA and achieve high optical properties. At the same time, by enhancing the orientation of PVA in advance, problems such as a decrease in the orientation of PVA and dissolution when immersed in water in the subsequent dyeing process and stretching process can be prevented, and high optical properties can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, compared with the case where the PVA-based resin layer does not contain a halide, the disturbance of the orientation of polyvinyl alcohol molecules and the decrease in the orientation can be suppressed. Thereby, the optical properties of the polarizer obtained through treatment steps such as a dyeing treatment and a stretching treatment in water, which are performed by immersing the laminate in a liquid, can be improved. Furthermore, by shrinking the laminate in the width direction by the drying shrinkage treatment, the optical properties can be improved.The obtained resin substrate / polarizer laminate may be used as it is (i.e., the resin substrate may serve as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate / polarizer laminate, and any appropriate protective layer according to the purpose may be laminated on the peeled surface and used. Details of such a method for manufacturing a polarizer are described, for example, in JP-A-2012-73580 and Japanese Patent No. 6470455. The entire disclosures of these publications are incorporated herein by reference.

[0026] The polarizer 21 is preferably composed of a laminate of two or more layers, and more preferably can be composed of a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate.

[0027] The thickness of the polarizer 21 is preferably 15 μm or less, more preferably 12 μm or less, still more preferably 10 μm or less, particularly preferably 8 μm or less, and typically 1 μm or more, preferably 3 μm or more.

[0028] The polarizer 21 preferably exhibits absorption dichroism at any wavelength in the wavelength range of 380 nm to 780 nm. The single transmittance of the polarizer 21 is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, more preferably 44.5% to 46.0%. The degree of polarization of the polarizer 21 is preferably 97.0% or more, more preferably 99.0% or more, still more preferably 99.9% or more.

[0029] B-1-2. Protective Layer The protective layer 22 is formed of any suitable film that can be used as a protective layer for the polarizer 21. Specific examples of the material that is the main component of the film include cellulose resins such as triacetyl cellulose (TAC), and transparent resins such as polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, acetate-based resins, etc. Further, thermosetting resins or ultraviolet curable resins such as (meth)acrylic-based, urethane-based, (meth)acrylic urethane-based, epoxy-based, silicone-based resins, etc. are also included. Note that the “(meth)acrylic-based resin” refers to acrylic-based resin and / or methacrylic-based resin. In addition to these, for example, glassy polymers such as siloxane-based polymers are also included. Also, the polymer film described in JP-A-2001-343529 (WO01 / 37007) can be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used. For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the above resin composition.

[0030] The protective layer 22 preferably contains a (meth)acrylic-based resin. As the (meth)acrylic-based resin, for example, a (meth)acrylic-based resin having a glutarimide structure is used. The (meth)acrylic-based resin having a glutarimide structure is described in, for example, JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, JP-A-2006-328334, JP-A-2006-337491, JP-A-2006-337492, JP-A-2006-337493, JP-A-2006-337569, JP-A-2007-009182, JP-A-2009-161744, JP-A-2010-284840. These descriptions are incorporated herein by reference.

[0031] The thickness of the protective layer 22 is typically 300 μm or less, preferably 100 μm or less, more preferably 5 μm to 80 μm, and even more preferably 10 μm to 60 μm. When surface treatment is performed, the thickness of the protective layer 22 is the thickness including the thickness of the surface treatment layer.

[0032] B-2. First Surface Protection Film The first surface protection film 1 has a long shape and can typically be wound into a roll. As described above, a plurality of first through-holes 1a and second through-holes 1b are formed in the first surface protection film 1 in advance. Further, third through-holes 1c are formed in the first surface protection film 1 in advance as required. The method for forming the through-holes is not particularly limited, and examples include machining, laser processing, etching by chemical reaction, and the like. The first surface protection film 1 has a base material 11 and an adhesive layer 12.

[0033] The base material 11 is formed of any suitable film. Specific examples of the material that is the main component of the film include, for example, ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, copolymer resins thereof, and the like. Preferably, ester resins are mentioned. When the material of the base material 11 is an ester resin, the hardness of the first surface protection film 1 can be improved, and deformation of the through-holes during conveyance and / or lamination can be suppressed.

[0034] The thickness of the base material 11 is typically 20 μm to 250 μm, preferably 30 μm to 150 μm.

[0035] The adhesive layer 12 is formed from any suitable adhesive (pressure-sensitive adhesive). Examples of the adhesive include, for example, (meth)acrylic adhesives, urethane adhesives, silicone adhesives, etc., and preferably, (meth)acrylic adhesives. The “(meth)acrylic adhesive” refers to acrylic adhesives and / or methacrylic adhesives.

[0036] The thickness of the adhesive layer 12 is typically 1 μm to 20 μm, and preferably 3 μm to 10 μm.

[0037] Such a first surface protection film 1 is attached to the polarizing plate 2 when the adhesive layer 12 comes into contact with the polarizer 21. In the state where the first surface protection film 1 is attached to the polarizing plate 2, the base material 11 is located on the side opposite to the polarizer 21 with respect to the adhesive layer 12.

[0038] B-3. Second surface protection film The second surface protection film 3 has a long shape and is typically rollable. The second surface protection film 3 can be described in the same manner as the first surface protection film 1 except that it does not have through-holes (first through-hole 1a, second through-hole 1b, and third through-hole 1c). The second surface protection film 3 has a base material 31 that can be described in the same manner as the base material 11 and an adhesive layer 32 that can be described in the same manner as the adhesive layer 12. Such a second surface protection film 3 is attached to the polarizing plate 2 when the adhesive layer 32 comes into contact with the protective layer 22. In the state where the second surface protection film 3 is attached to the polarizing plate 2, the base material 31 is located on the side opposite to the protective layer 22 with respect to the adhesive layer 32.

[0039] C. Decolorization treatment process of polarizer Next, the laminate 4 is subjected to chemical decolorization treatment, and a treatment liquid (typically, a basic solution) is brought into contact with the portion of the polarizer 21 exposed from the plurality of first through-holes 1a through the first through-holes 1a. The contact of the basic solution with the polarizer 21 is typically carried out by immersing the laminate 4 in the basic solution while being conveyed, as shown in FIG. 1. After the laminate 4 is immersed in the basic solution, the laminate 4 may be immersed in a cleaning liquid (for example, water, alcohol, and a mixed solvent thereof) and cleaned while being conveyed.

[0040] When the polarizer 21 contains iodine as a dichroic substance, when a basic solution is brought into contact with a predetermined portion of the polarizer 21, the iodine content of the contact portion is easily reduced, and a non-polarizing portion 21a can be selectively formed in the contact portion. As a result, a predetermined portion of the polarizer 21 can be decolorized, and a plurality of non-polarizing portions 21a can be formed on the polarizer 21. When the iodine complex is destroyed to form a non-polarizing portion, iodine may remain in the non-polarizing portion. Then, when the iodine complex is formed again with the use of the polarizer, the non-polarizing portion may not have desired characteristics. On the other hand, when the non-polarizing portion 21a is formed by the contact of the basic solution with the polarizer 21, iodine itself is removed from the polarizer 21 (substantially, the non-polarizing portion 21a) along with the removal of the basic solution. As a result, the change in the characteristics of the non-polarizing portion 21a associated with the use of the polarizer 21 can be suppressed.

[0041] The content of the dichroic substance (typically, iodine) in the non-polarizing portion 21a is preferably 1.0% by weight or less, more preferably 0.5% by weight or less, and still more preferably 0.2% by weight or less. If the content of the dichroic substance in the non-polarizing portion is within such a range, desired transparency can be sufficiently imparted to the non-polarizing portion 21a. For example, when a non-polarizing portion is provided in the camera unit of an image display device, excellent photographing performance can be realized from both the viewpoints of brightness and color tone. On the other hand, the lower limit value of the content of the dichroic substance in the non-polarizing portion 21a is usually below the detection limit value. When iodine is used as the dichroic substance, the iodine content is determined, for example, from the X-ray intensity measured by fluorescent X-ray analysis using a calibration curve prepared in advance using a standard sample.

[0042] The difference between the content of the dichroic substance in the portion of the polarizer 21 other than the non-polarizing portion 21a and the content of the dichroic substance in the non-polarizing portion 21a is preferably 0.5% by weight or more, more preferably 1% by weight or more. If the difference in content is within such a range, a non-polarizing portion having desired transparency can be formed.

[0043] The transmittance of the non-polarizing portion 21a (for example, the transmittance measured with light having a wavelength of 550 nm at 23°C) is preferably 50% or more, more preferably 60% or more, still more preferably 75% or more, and particularly preferably 90% or more. With such a transmittance, the non-polarizing portion has desired transparency. As a result, when the polarizing plate is arranged such that the non-polarizing portion corresponds to the camera portion of the image display device, an adverse effect on the photographing performance of the camera can be prevented.

[0044] The basic solution contains a basic compound and a solvent that disperses and / or dissolves the basic compound. As the basic compound, any suitable basic compound can be used. Examples of the basic compound include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, hydroxides of alkaline earth metals such as calcium hydroxide, inorganic alkali metal salts such as sodium carbonate, organic alkali metal salts such as sodium acetate, and aqueous ammonia. These basic compounds can be used alone or in combination. Among these basic compounds, hydroxides of alkali metals and / or alkaline earth metals are preferably mentioned, and sodium hydroxide, potassium hydroxide, and lithium hydroxide are more preferably mentioned. When the basic compound contains hydroxides of alkali metals and / or alkaline earth metals, the iodine complex can be efficiently ionized, and the non-polarizing portion can be formed more simply.

[0045] As the solvent, any suitable solvent can be used. Examples of the solvent include water, alcohols such as ethanol and methanol, ether, benzene, chloroform, and mixed solvents thereof. Among these solvents, water and alcohol are preferably used. When the solvent contains water and / or alcohol, iodine ions can smoothly transfer from the polarizer 21 to the solvent, and the iodine ions can be easily removed along with the removal of the basic solution.

[0046] The concentration of the basic solution is, for example, 0.01N to 5N, preferably 0.05N to 3N, and more preferably 0.1N to 2.5N. If the concentration of the basic solution is within such a range, the iodine concentration of the portion of the polarizer 21 exposed from the first through-hole 1a can be efficiently reduced, and the ionization of the iodine complex in the polarizer 21 excluding the said portion can be suppressed.

[0047] D. Post-treatment process of the decolorization treatment In one embodiment of the present invention, a post-treatment process is included after the decolorization treatment of the polarizer. When a treatment liquid (typically a basic solution) is brought into contact with the portions of the polarizer 21 exposed from the plurality of first through-holes 1a to form the non-polarizing portions 21a, metal salts of alkali metals and / or alkaline earth metals may be generated in the non-polarizing portions 21a. These can generate hydroxide ions, and the generated hydroxide ions can act (decompose and reduce) on the dichroic substances (for example, iodine complexes) present around the non-polarizing portions 21a to expand the non-polarizing region (low-concentration region). Therefore, by performing a post-treatment process to reduce the metal salts of alkali metals and / or alkaline earth metals, it is considered that the expansion of the non-polarizing region over time can be suppressed, and the desired non-polarizing portion shape can be maintained.

[0048] Typical examples of the metal salts that can generate the above hydroxide ions include borates. Borates can be generated, for example, by neutralizing the boric acid used in the above stretching treatment with a basic solution (typically a solution of an alkali metal hydroxide and / or an alkaline earth metal hydroxide). Note that borates (metaborates) can be hydrolyzed to generate hydroxide ions, for example, when the polarizer is placed in a humid environment.

[0049] In the post-treatment step, a post-treatment liquid (typically, an acidic solution) is brought into contact with the non-polarizing portion 21a exposed from the plurality of first through-holes 1a through the first through-holes 1a. The contact of the acidic solution with the non-polarizing portion 21a is typically carried out by immersing the laminate 4 in the acidic solution while conveying it, as shown in FIG. 1. Note that after the laminate 4 is immersed in the acidic solution, the laminate 4 may be immersed in a cleaning liquid (e.g., water, alcohol, and a mixed solvent thereof) and cleaned while being conveyed.

[0050] When the non-polarizing portion 21a is brought into contact with a post-treatment liquid (typically, an acidic solution), metal salts of alkali metals and / or alkaline earth metals can migrate into the post-treatment liquid (typically, an acidic solution), and the content of metal salts of alkali metals and / or alkaline earth metals in the non-polarizing portion 21a can be reduced. In particular, when the post-treatment liquid is an acidic solution, hydroxides of alkali metals and / or alkaline earth metals remaining in the non-polarizing portion 21a can be neutralized, and the alkali metals and / or alkaline earth metals can be chemically removed.

[0051] The content of metal salts of alkali metals and / or alkaline earth metals in the non-polarizing portion 21a after the post-treatment step is preferably 3.6 wt% or less, more preferably 2.5 wt% or less, still more preferably 1.0 wt% or less, and particularly preferably 0.5 wt% or less.

[0052] The acidic solution contains an acidic compound and a solvent that disperses and / or dissolves the acidic compound. As the acidic compound, any suitable acidic compound can be used. Examples of the acidic compound include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrogen fluoride, and boric acid, and organic acids such as formic acid, oxalic acid, citric acid, acetic acid, and benzoic acid. The acidic compounds can be used alone or in combination. Among the acidic compounds, inorganic acids are preferably used, and hydrochloric acid, sulfuric acid, and nitric acid are more preferably used.

[0053] As the solvent, any suitable solvent can be used. The solvent is as described in the above item C, "Decolorization treatment step of the polarizer".

[0054] The concentration of the acidic solution is, for example, 0.01N to 5N, preferably 0.05N to 3N, and more preferably 0.1N to 2.5N.

[0055] E. Winding process of the laminate Next, the laminate 4 including the polarizer 21 on which a plurality of non-polarizing portions 21a are formed is continuously wound into a roll shape by a rotating shaft (not shown) while applying an arbitrary appropriate winding tension. Thereby, a roll 5 of the laminate 4 is formed. In the roll 5, the first surface protection film 1 of the laminate 4 is located on the outer side in the radial direction of the roll 5 with respect to the polarizing plate 2 to which the first surface protection film 1 is attached, and the second surface protection film 3 is located on the inner side in the radial direction of the roll 5 with respect to the polarizing plate 2 to which the second surface protection film 3 is attached.

[0056] The winding tension is typically 50N to 300N, preferably 70N to 250N. When the winding tension is below the above upper limit, it is possible to stably suppress the occurrence of indentations on the roll. When the winding tension is above the above lower limit, it is possible to suppress the occurrence of winding deviation on the roll.

[0057] Also, the length of the laminate 4 to be wound (winding length) is typically 50m to 6000m, preferably 150m to 4000m. When the winding length is below the above upper limit, it is possible to suppress the stress applied to the center of the roll from becoming excessively large. When the winding length is above the above lower limit, it is possible to improve the productivity of the polarizing plate pieces.

[0058] F. Cutting process of the polarizer piece Next, after pulling out a part of the laminate 4 from the roll 5, the first surface protection film 1 is removed (typically peeled off) from the pulled-out laminate 4. Then, a detection unit (typically a camera) (not shown) detects the position of the non-polarizing portion 21a, and based on the detected position of the non-polarizing portion 21a, a cutting line C is set. Next, using a punching blade (not shown), the polarizing plate 2 is cut along the cutting line C. As a result, the polarizing plate piece 20 is cut out from the polarizing plate 2. The polarizing plate piece 20 includes a polarizer piece 210 including the non-polarizing portion 21a and a protective layer piece 220. In other words, the polarizer piece 210 including the non-polarizing portion 21a is cut out from the polarizer 21.

[0059] The planar shape of the polarizing plate piece 20 corresponds to the above-described cutting line C and can be any appropriate shape. Examples of the planar shape of the polarizing plate piece 20 include a circular shape, an elliptical shape, a square shape, a rectangular shape, a rhombus shape, etc., and preferably, a rectangular shape. The polarizer piece 210 having a rectangular shape has a long side and a short side. The long side direction of the polarizer piece 210 may be substantially parallel to the absorption axis direction of the polarizer 21 or may intersect the absorption axis direction of the polarizer 21. In this specification, the expression "substantially parallel" includes the case where the angle formed by two directions is 0° ± 7°, preferably 0° ± 5°, and more preferably 0° ± 3°.

[0060] Thereafter, the above operation is repeated, and the punching blade (not shown) is moved to cut out the next polarizing plate piece 20 from the polarizing plate 2. In one embodiment of the present invention, the punching blade (not shown) is linearly moved from one side to the other side in the width direction to sequentially cut out the polarizing plate pieces 20 from the polarizing plate 2. After the cutting out of the polarizing plate pieces 20 from the polarizing plate 2 in one row in the width direction is completed, the polarizing plate 2 is conveyed by a predetermined feed pitch, and the cutting operation is performed for the next row. By repeating this a predetermined number of times with one cycle being the cutting operation in one row in the width direction and the conveyance of the polarizing plate 2 by one pitch after the operation, a plurality of polarizer pieces 210 can be cut out from the long polarizing plate 2.

Example

[0061] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measurement methods for each property are as follows.

[0062] (1) Roll hardness measurement On the surface of the roll of the laminate obtained in the examples and comparative examples, a roll hardness measuring instrument (manufactured by Tapio, measurement method: measurement of the deceleration of a small hammer, measurement pitch: 1 mm (30 taps / second)) was brought into contact, and from one end to the other end in the axial direction of the roll, 1080 points were measured at a 1 mm pitch. Table 1 shows the maximum hardness of the roll, the minimum hardness of the roll, and the difference (Gap) between them. Also, the laminate was pulled out from the roll to peel off the first surface protection film, and visually, the number of indentations with a diameter of 1 mm or more per 1 m of the polarizer was counted. Then, the number of indentations was evaluated according to the following criteria. The results are shown in Table 1. 2 〇: One or less indentations 〇: One or less indentations △: Two or more and four or less indentations ×: Five or more indentations

[0063] [Example 1] 1. Production of polarizing plate As a thermoplastic resin substrate, an amorphous isophthalic acid copolymerized polyethylene terephthalate film (thickness: 100 μm, width: 3900 mm) having a long shape and a Tg of about 75 °C was used, and one side of the resin substrate was subjected to corona treatment. 13 parts by weight of potassium iodide was added to 100 parts by weight of a PVA-based resin in which polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer") were mixed at a ratio of 9:1, and the mixture was dissolved in water to prepare a PVA aqueous solution (coating solution). The above PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60 °C to form a PVA-based resin layer with a thickness of 13 μm, and a laminate was produced. The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130 °C (air-assisted stretching treatment). Next, the laminate was immersed in an insolubilization bath at a liquid temperature of 40 °C (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment). Next, the laminate was immersed in a dyeing bath at a liquid temperature of 30 °C (an aqueous iodine solution obtained by blending iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer became a desired value (dyeing treatment). Next, the laminate was immersed in a crosslinking bath at a liquid temperature of 40 °C (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (crosslinking treatment). Thereafter, while immersing the laminate in an aqueous boric acid solution at a liquid temperature of 70 °C (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%), uniaxial stretching was performed in the longitudinal direction (lengthwise direction) between rolls with different peripheral speeds so that the total draw ratio became 5.5 times (stretching treatment in water). Thereafter, the laminate was immersed in a washing bath at a liquid temperature of 20 °C (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). Thereafter, while drying in an oven maintained at about 90 °C, it was brought into contact with a SUS heating roll whose surface temperature was maintained at about 75 °C (dry shrinkage treatment). In this way, a polarizer having a thickness of about 5 μm was formed on the resin substrate. An acrylic resin film (thickness: 40 μm) having a glutarimide structure as a protective layer was laminated via an ultraviolet curable adhesive on the surface of the obtained polarizer (the surface opposite to the resin substrate). Specifically, it was coated so that the total thickness of the curable adhesive became about 2.0 μm, and laminated using a roll machine. Thereafter, UV light was irradiated from the acrylic resin film side to cure the adhesive. Next, the resin substrate was peeled off to obtain a polarizing plate (width: 1300 mm) having a structure of acrylic resin film (protective layer) / polarizer.

[0064] 2. The first surface protection film On one surface of a long ester resin film (base material, thickness: 38 μm, width: 1300 mm), an acrylic adhesive was applied to a thickness of 5 μm to obtain a first surface protection film. On the first surface protection film, using a pinnacle (registered trademark) blade, first through-holes with a diameter of 3 mm were formed at intervals of 220 mm in the width direction. Also, rows in which a plurality of the first through-holes are arranged in the width direction were formed at intervals of 310 mm in the long direction. Further, as shown in FIG. 5, between the first through-hole located at one end in the width direction among the first through-holes in each row and the one end edge in the width direction of the first surface protection film, a second through-hole with a diameter of 3 mm was formed. The second through-hole was arranged so as to overlap with an imaginary line that collectively passes through the plurality of first through-holes included in each row in the width direction. complex Among the number of first through-holes in each row, a second through-hole with a diameter of 3 mm was formed between the first through-hole located at one end in the width direction and the one end edge in the width direction of the first surface protection film. The second through-hole was arranged so as to overlap with an imaginary line that collectively passes through the plurality of first through-holes included in each row in the width direction.

[0065] 3. Second surface protection film On one surface of a long ester resin film (base material, thickness 38 μm, width: 1300 mm), an acrylic adhesive was applied to a thickness of 5 μm to obtain a second surface protection film.

[0066] 4. Production of laminate and roll After laminating the second surface protection film on the protective layer of the polarizing plate, the first surface protection film was laminated on the polarizer of the polarizing plate. Thereby, a long laminate having a structure of the first surface protection film / polarizing plate / second surface protection film was obtained. Next, the long laminate was wound around a rotating shaft under the conditions of a winding tension of 240 N and a winding length of 4000 m. Thereby, a roll of the laminate was obtained.

[0067] [Example 2] As shown in FIG. 6, a roll of the laminate was obtained in the same manner as in Example 1, except that the diameter of the second through-hole was changed to 5 mm.

[0068] [Example 3] As shown in FIG. 7, a roll of the laminate was obtained in the same manner as in Example 1, except that the diameter of the second through-hole was changed to 1 mm.

[0069] [Example 4] As shown in Fig. 9, a roll of laminate was obtained in the same manner as in Example 1, except that a plurality of second through-holes with a diameter of 1 mm were formed so as to be arranged in the longitudinal direction corresponding to each row of the first through-holes.

[0070] [Example 5] As shown in Fig. 10, a roll of laminate was obtained in the same manner as in Example 4, except that in addition to a plurality of second through-holes, a plurality of third through-holes with a diameter of 1 mm were formed so as to be arranged in the longitudinal direction corresponding to each row of the first through-holes. The plurality of third through-holes were complex located between the first through-hole located at the other end in the width direction among the number of first through-holes in each row and the other end edge in the width direction of the first surface protection film.

[0071] [Example 6] As shown in Fig. 8, a roll of laminate was obtained in the same manner as in Example 1, except that the second through-holes were formed by shifting them in the longitudinal direction from the virtual line passing through the plurality of first through-holes included in the row, and the third through-holes with a diameter of 3 mm were formed between the first through-hole located at the other end in the width direction among the plurality of first through-holes in each row and the other end edge in the width direction of the first surface protection film. Further, the third through-holes were formed by shifting them to the opposite side of the first through-holes with respect to the above virtual line.

[0072] [Comparative Example 1] As shown in Fig. 11, a roll of laminate was obtained in the same manner as in Example 1, except that the second through-holes were not formed in the first surface protection film.

[0073] [Comparative Example 2] As shown in Fig. 12, a roll of laminate was obtained in the same manner as in Comparative Example 1, except that the positions of the plurality of first through-holes were changed.

[0074]

Table 1

[0075] [Evaluation] As is clear from Table 1, it can be seen that by forming the second through-hole at a predetermined position, it is possible to suppress the local increase in the hardness (roll internal stress) of the roll of the laminate, and it is possible to suppress the occurrence of indentations on the polarizer.

Industrial Applicability

[0076] The method for manufacturing a polarizer sheet of the present invention is suitably used for manufacturing a polarizer used in an image display device with a camera (liquid crystal display device, organic EL device) such as a mobile phone such as a smartphone, a notebook PC, or a tablet PC.

Explanation of Signs

[0077] 1 First surface protection film 1a First through-hole 1b Second through-hole 1c Third through-hole 2 Polarizing plate 21 Polarizer 21a Non-polarizing part 22 Protective layer 3 Second surface protection film

Claims

1. A step of forming a laminate by laminating a long surface protection film having a plurality of first through holes arranged at intervals in a width direction orthogonal to the long direction of the surface protection film on a long polarizer having a dichroic substance; A step of decolorizing a portion of the polarizer exposed from the plurality of first through holes through the first through holes to form a plurality of non-polarized portions on the polarizer; A step of winding a laminate including the polarizer on which the plurality of non-polarized portions are formed into a roll by applying a winding tension of 50 N to 300 N; A step of cutting out a plurality of polarizer pieces including the non-polarized portions from the polarizer after the winding, and The surface protection film, further has a second through hole located between a first through hole located at one end in the width direction among the plurality of first through holes and one end edge of the surface protection film in the width direction, the second through hole is formed in a margin portion located outside the polarizer piece, the opening areas of the plurality of first through holes are the same as each other, the opening area of the second through hole is 0.1 or more and 5.0 or less with respect to the opening area of each of the first through holes, or a method for manufacturing a polarizer piece, wherein a plurality of the second through holes are arranged at intervals in the long direction, and the opening area of the second through hole is 0.01 or more and less than 0.5 with respect to the opening area of each of the first through holes.

2. A step of forming a laminate by laminating a long surface protection film having a plurality of first through holes arranged at intervals in a width direction orthogonal to the long direction of the surface protection film on a long polarizer having a dichroic substance; A step of decolorizing a portion of the polarizer exposed from the plurality of first through holes through the first through holes to form a plurality of non-polarized portions on the polarizer; A step of winding a laminate including the polarizer on which the plurality of non-polarized portions are formed into a roll by applying a winding tension of 50 N to 300 N; A step of cutting out a plurality of polarizer pieces including the non-polarized portions from the polarizer after the winding, and The surface protection film, further has a second through hole located between a first through hole located at one end in the width direction among the plurality of first through holes and one end edge of the surface protection film in the width direction, the opening areas of the plurality of first through holes are the same as each other, A method for manufacturing a polarizer sheet, wherein an opening area of the second through-hole is 1.5 or more and 5.0 or less with respect to an opening area of each of the first through-holes.

3. A method for manufacturing a polarizer sheet, comprising: laminating a surface protection film, which is a long surface protection film having a plurality of first through-holes arranged at intervals in a width direction orthogonal to a long direction of the surface protection film, on a long polarizer having a dichroic substance to form a laminate; decolorizing a portion of the polarizer exposed from the plurality of first through-holes through the first through-holes to form a plurality of non-polarized portions on the polarizer; winding up the laminate including the polarizer on which the plurality of non-polarized portions are formed in a roll shape by applying a winding tension of 50 N to 300 N; after winding up, cutting out a plurality of polarizer sheets including the non-polarized portions from the polarizer. The surface protection film further has a second through-hole located between a first through-hole located at one end in the width direction among the plurality of first through-holes and one end edge of the surface protection film in the width direction; opening areas of each of the plurality of first through-holes are the same as each other; an opening area of the second through-hole is 0.01 or more and less than 0.5 with respect to an opening area of each of the first through-holes; the second through-holes are arranged in plurality at intervals in the long direction.

4. The surface protection film further has a third through-hole located between a first through-hole located at the other end in the width direction among the plurality of first through-holes and the other end edge of the surface protection film in the width direction. The method for manufacturing a polarizer sheet according to any one of Claims 1 to 3.

5. Each of a width direction interval between the first through-hole located at one end in the width direction and the second through-hole, and a width direction interval between the second through-hole and one end edge of the surface protection film is equal to or less than a width direction interval between adjacent first through-holes among the plurality of first through-holes. The method for manufacturing a polarizer sheet according to any one of Claims 1 to 4.

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