JP6604714B2 - Manufacturing method of polarizer - Google Patents

Description

  The present invention relates to a method for manufacturing a polarizer. In more detail, this invention relates to the manufacturing method of the elongate polarizer which has a non-polarizing part.

  Some image display devices such as mobile phones and notebook personal computers (PCs) are equipped with internal electronic components such as cameras. Various studies have been made for the purpose of improving the camera performance and the like of such an image display device (for example, Patent Documents 1 to 6). However, with the rapid spread of smartphones and touch panel type information processing devices, further improvements in camera performance and the like are desired. Further, in order to cope with diversification and high functionality of the shape of the image display device, there is a demand for a polarizing plate partially having polarization performance. In order to realize these demands industrially and commercially, it is desired to manufacture an image display device and / or its components at an acceptable cost. Matters are left behind.

JP 2011-81315 A JP 2007-241314 A US Patent Application Publication No. 2004/0212555 Korean Published Patent No. 10-2012-0118205 Korean Patent No. 10-1293210 JP 2012-137738 A

  The present invention has been made in order to solve the above-described conventional problems, and its main purpose is polarization that contributes to multi-functionality and high functionality of electronic devices such as image display devices and has no variation in quality. The object is to provide a child manufacturing method.

The method for producing a polarizer having a non-polarizing part of the present invention includes a long polarizer and a surface protective film disposed on one side of the polarizer, and the polarizer is exposed on the one side. In this order, the polarizing film laminate having an exposed portion is brought into contact with a basic solution, and the polarizing film laminate is immersed in a treatment bath maintained at a pH of 8 or less while being conveyed in the longitudinal direction.
In one embodiment, the contact is performed by immersing the polarizing film laminate in a basic solution.
In one embodiment, the pH of the treatment bath is measured, and the supply amount of the treatment liquid is feedback-controlled based on the measurement signal.
In one embodiment, the liquid level of the treatment bath is measured, and the supply amount of the treatment liquid is feedback-controlled based on the measurement signal.
In one embodiment, the exposed portions are arranged at a predetermined interval in at least the longitudinal direction of the polarizer.

  According to the present invention, a polarizing film laminate comprising a long polarizer and a surface protective film disposed on one side thereof, and having an exposed portion where the polarizer is exposed on the one side is used as a basic solution. Then, the basic solution is uniformly removed from the polarizing film laminate (exposed portion) by immersing it in a treatment bath maintained at pH 8 or lower while transporting the polarizing film laminate in the longitudinal direction. Thus, uneven color removal due to the basic solution can be prevented. As a result, it is possible to obtain a polarizer (for example, a polarizer having a predetermined size) which has excellent uniformity in the non-polarizing portion of the obtained polarizer and has no variation in quality. As a result, the method for producing a polarizer according to the present invention can contribute to multi-functionalization and high-functionalization of an electronic device such as an image display device.

It is a schematic perspective view of the polarizing film laminated body by one embodiment of this invention. It is a fragmentary sectional view of the polarizing film laminated body shown in FIG. It is a schematic perspective view explaining lamination | stacking with the polarizer and surface protection film by one Embodiment of this invention. It is the schematic explaining the manufacturing method of the polarizer which has a non-polarization part by one Embodiment of this invention. It is the schematic explaining the manufacturing method of the polarizer which has a non-polarization part by another embodiment of this invention.

  Hereinafter, although embodiment of this invention is described, this invention is not limited to these embodiment.

A. 1 and 2 are schematic views of a polarizing film laminate according to one embodiment of the present invention, FIG. 1 is a perspective view of the polarizing film laminate, and FIG. 2 is a polarized light shown in FIG. It is a fragmentary sectional view of a film laminated body. The polarizing film laminate 100 includes a polarizer 10 and a surface protective film 20 disposed on one surface side (upper surface side in the illustrated example) of the polarizer 10 and on the other surface side (lower surface side in the illustrated example) of the polarizer 10. The disposed protective film 30 and the second surface protective film 40 are provided. The polarizing film laminate 100 has exposed portions 11, 11,... Where the polarizer 10 is exposed on one surface side (the upper surface side in the illustrated example). In the example of illustration, the exposed part 11 is provided by forming the through-hole 21 in the surface protection film 20 arrange | positioned at the one surface side of the polarizer 10 (For convenience, the surface protection film which has a through-hole is 1st. 1 may be referred to as a surface protective film 1). A non-polarizing portion can be formed in a portion corresponding to the exposed portion 11 of the polarizer 10 by contact with a basic solution described later.

  The surface protection film 20 is used for the purpose of temporarily protecting the polarizer 10 during manufacturing, and is removed from the polarizer 10 at any appropriate timing. Therefore, the surface protective film 20 is laminated on the polarizer 10 so as to be peelable. Although not illustrated, typically, the surface protective film 20 is bonded to the polarizer 10 via any appropriate adhesive. In the present specification, the term “protective film” means a polarizer protective film such as the protective film 30 and is different from a surface protective film that is temporarily used during production.

  The polarizer 10 has a long shape, and typically, as shown in FIG. 1, the polarizing film laminate 100 is wound in a roll shape. In the present specification, the “elongate shape” means an elongated shape having a sufficiently long length with respect to the width, for example, an elongated shape having a length of 10 times or more, preferably 20 times or more with respect to the width. Including. In the example of illustration, the elongate direction of the elongate surface protection film 20 and the elongate direction of the polarizer 10 are made substantially parallel. In one embodiment, the width dimension of the elongated surface protective film 20 is designed to be substantially the same as or larger than the width dimension of the polarizer 10.

  The exposed portions can be arranged at a predetermined interval in at least the longitudinal direction of the polarizer. In the illustrated example, the exposed portions 11 are arranged at predetermined intervals in the longitudinal direction and the width direction of the polarizer 10. The arrangement pattern of the exposed portions 11 can be appropriately set according to the purpose. For example, when the exposed portion 11 is cut into a predetermined size (for example, cutting and punching in the longitudinal direction and / or the width direction) in order to attach the polarizer 10 to an image display device of a predetermined size, the image display device It is arrange | positioned in the position corresponding to the camera part.

  In one embodiment, the plan view shape of the exposed portion 11 (the shape seen from one side of the polarizing film laminate 100) does not adversely affect the camera performance of the image display device in which the polarizer is used. Any suitable shape can be employed. Examples of the plan view shape of the exposed portion include a substantially circular shape or a substantially rectangular shape. Specific examples include a circle, an ellipse, a square, a rectangle, and a rhombus. By appropriately setting the shape of the through hole of the surface protective film described later, an exposed portion having a desired plan view shape can be formed.

A-1. Polarizer The polarizer 10 is typically composed of a resin film. The resin film is typically a polyvinyl alcohol-based resin (hereinafter referred to as “PVA-based resin”) film containing a dichroic substance. A single film may be sufficient as a polarizer and the resin layer (typically PVA-type resin layer) formed on the resin base material may be sufficient as it.

  Examples of the dichroic substance include iodine and organic dyes. These may be used alone or in combination of two or more. Preferably, iodine is used. When the non-polarizing part is formed by decolorization by chemical treatment described later, the iodine complex contained in the resin film (polarizer) is appropriately reduced, so that, for example, non-polarizing parts having characteristics suitable for use in the camera part are used. This is because a polarizing part can be formed.

  Any appropriate resin can be used as the PVA resin for forming the PVA resin film. Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. An ethylene-vinyl alcohol copolymer can be obtained by saponifying an ethylene-vinyl acetate copolymer. The degree of saponification of the PVA resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. . The saponification degree can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a saponification degree, a polarizer having excellent durability can be obtained. If the degree of saponification is too high, there is a risk of gelation.

  The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average degree of polymerization is usually 1000 to 10000, preferably 1200 to 4500, more preferably 1500 to 4300. The average degree of polymerization can be determined according to JIS K 6726-1994.

  The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single transmittance (Ts) of the polarizer is preferably 39% or more, more preferably 39.5% or more, still more preferably 40% or more, and particularly preferably 40.5% or more. The theoretical upper limit of the single transmittance is 50%, and the practical upper limit is 46%. Further, the single transmittance (Ts) is a Y value measured with a 2 degree visual field (C light source) of JIS Z8701 and corrected for visibility, for example, using a microspectroscopic system (Lambda Vision, LVmicro). Can be measured. The polarization degree of the polarizer is preferably 99.9% or more, more preferably 99.93% or more, and further preferably 99.95% or more.

  The thickness of the polarizer can be set to any appropriate value. The thickness is preferably 30 μm or less, more preferably 25 μm or less, still more preferably 20 μm or less, and particularly preferably less than 10 μm. On the other hand, the thickness is preferably 0.5 μm or more, more preferably 1 μm or more. With such a thickness, a polarizer having excellent durability and optical characteristics can be obtained. Moreover, a non-polarizing part can be formed favorably, so that thickness is thin. For example, when forming a non-polarization part by decoloring by the chemical process mentioned later, the contact time of a process liquid and a resin film (polarizer) can be shortened.

  The absorption axis of the polarizer can be set in any appropriate direction depending on the purpose. The direction of the absorption axis may be, for example, the long direction or the width direction. A polarizer having an absorption axis in the longitudinal direction has an advantage of excellent manufacturing efficiency. For example, a polarizer having an absorption axis in the width direction has an advantage that it can be laminated with a retardation film having a slow axis in the longitudinal direction and a so-called roll-to-roll. In this specification, “roll-to-roll” refers to laminating the rolls in the same long direction while conveying a roll-shaped film.

  The polarizer can be made by any suitable method. When the polarizer is a single PVA-based resin film, the polarizer can be produced by a method well known and commonly used in the art. When the polarizer is a PVA-based resin layer formed on a resin base material, the polarizer can be produced by, for example, a method described in JP2012-73580A. This publication is incorporated herein by reference in its entirety.

A-2. Surface protective film The surface protective film is provided on one surface side of the polarizer so that a desired exposed portion is formed. In the illustrated example, the surface protective film 20 has through holes 21, 21,... Arranged in a predetermined pattern. The position where the through hole is provided corresponds to the position where the exposed portion of the polarizer is formed. The through hole may have any suitable shape. The shape of the through hole corresponds to the shape of the exposed portion formed in plan view. The through hole is formed by, for example, mechanical punching (for example, punching, engraving blade punching, plotter, water jet) or removal of a predetermined portion (for example, laser ablation or chemical dissolution).

  The surface protective film is preferably a film having a high hardness (for example, elastic modulus). This is because deformation of the through-holes during conveyance and / or lamination can be prevented. Surface protective film forming materials include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. Etc. Preference is given to ester resins (especially polyethylene terephthalate resins). Such a material is advantageous in that it is inexpensive and has a sufficiently high elastic modulus, and deformation of the through-hole is hardly caused even when tension is applied during transportation and / or lamination.

  The thickness of the surface protective film is typically 20 μm to 250 μm, preferably 30 μm to 150 μm. With such a thickness, there is an advantage that deformation of the through hole hardly occurs even when tension is applied during transportation and / or lamination.

The elastic modulus of the surface protective film is preferably 2.2 kN / mm ^{2 to} 4.8 kN / mm ² . If the elastic modulus of the surface protective film is in such a range, there is an advantage that deformation of the through-hole hardly occurs even when tension is applied during transportation and / or lamination. The elastic modulus is measured according to JIS K 6781.

  The tensile elongation of the surface protective film is preferably 90% to 170%. If the tensile elongation of the surface protective film is in such a range, there is an advantage that it is difficult to break during transportation. The tensile elongation is measured according to JIS K 6781.

  As one embodiment, as shown in FIG. 3, a surface-protective film 20 having through-holes 21, 21... Arranged in a long and predetermined pattern on a long polarizer 10 is rolled to roll. Is laminated. By using a surface protective film having a through hole, the exposed portion of the polarizer can be satisfactorily formed.

  As described above, the surface protective film 20 is typically detachably bonded to the polarizer 10 via any appropriate pressure-sensitive adhesive. Preferably, a through-hole is previously formed in the surface protective film on which the pressure-sensitive adhesive layer is formed, and this is bonded to the polarizer. As the pressure-sensitive adhesive used for laminating the surface protective film, for example, an acrylic resin, a styrene resin, a silicone resin, or the like is used as a base resin. And a pressure-sensitive adhesive composition containing a silane coupling agent and the like. The thickness of the pressure-sensitive adhesive layer is usually 5 μm to 60 μm, preferably 5 μm to 30 μm. If the pressure-sensitive adhesive layer is too thin, there is a possibility that problems such as lowering of the tackiness and easy mixing of bubbles may occur, and if it is too thick, problems such as the pressure-sensitive adhesive protruding may occur. An acrylic pressure-sensitive adhesive is preferably used from the viewpoints of chemical resistance, adhesiveness (for example, for preventing penetration of a solution at the time of dipping described later), a degree of freedom to an adherend, and the like.

A-3. Other Examples of the material for forming the protective film 30 include cellulose resins such as diacetylcellulose and triacetylcellulose, (meth) acrylic resins, cycloolefin resins, olefin resins such as polypropylene, and esters such as polyethylene terephthalate resins. Resin, polyamide resin, polycarbonate resin, and copolymer resins thereof. The thickness of the protective film is preferably 10 μm to 100 μm.

  The protective film may have an optical compensation function (that is, may have an appropriate refractive index ellipsoid, an in-plane retardation, and a thickness direction retardation depending on the purpose). The protective film is typically laminated on the polarizer via an adhesive layer (specifically, an adhesive layer or an adhesive layer). The adhesive layer is typically formed of a PVA adhesive or an active energy ray curable adhesive. The pressure-sensitive adhesive layer is typically formed of an acrylic pressure-sensitive adhesive.

  When the polarizer 10 is a resin layer formed on a resin base material, lamination of the protective film 30 and / or peeling of the resin base material can be performed. In one embodiment, a protective film is laminated by roll-to-roll on the surface of the polarizer of the resin substrate / polarizer laminate, and then the resin substrate is peeled off.

  The second surface protective film 40 may be the same film as the first surface protective film except that no through hole is provided. Furthermore, as the second surface protective film, a soft (eg, low elastic modulus) film such as a polyolefin (eg, polyethylene) film can be used. In one embodiment, the second surface protective film 40 is laminated on one side of the polarizer 10 by roll-to-roll. Specifically, the second surface protective film 40 is detachably bonded to the polarizer 10 or the protective film 30 via any appropriate adhesive. By using the second surface protective film, the polarizer or the polarizing plate (polarizer / protective film) can be appropriately protected in the chemical treatment described later. The second surface protective film may be laminated on the polarizer or the polarizing plate simultaneously with the first surface protective film, or may be laminated before the first surface protective film is laminated. You may laminate | stack after laminating | stacking a film. Preferably, the second surface protective film is laminated before the first surface protective film is laminated on the polarizer or the polarizing plate. With such a procedure, the protective film is prevented from being damaged, and the through-hole formed in the first surface protective film at the time of winding is prevented from being transferred as a mark to the protective film. Have advantages. In the case of laminating the second surface protective film before laminating the first surface protective film, for example, a laminate of the protective film and the second surface protective film is prepared, and this laminate is used as a resin base material. / After laminating on the laminate of polarizers, the resin substrate can be peeled off, and the first surface protective film can be laminated on the peeled surface.

  Although not shown, the polarizing film laminate of the present invention may further have any appropriate optical function layer depending on the purpose. Representative examples of the optical functional layer include a retardation film (optical compensation film) and a surface treatment layer.

B. Formation of a non-polarizing part The said non-polarizing part is typically formed by decoloring a polarizer by chemical treatment. When performing the chemical treatment, in addition to the protection by the first surface protective film, the other surface side of the polarizer 10 is preferably protected by any appropriate film material. As this film material, for example, when the protective film 30, the second surface protective film 40, and the polarizer 10 are resin layers formed on a resin base material, the resin base material is used.

  Hereinafter, formation of a non-polarization part is demonstrated concretely. As a representative example, a case will be described in which a non-polarizing portion is formed on a polarizer by decoloring by chemical treatment (hereinafter also referred to as chemical decoloration treatment) in the polarizing film laminate 100 of the illustrated example. It will be apparent to those skilled in the art that the same procedure can be applied even if the configuration is different from the illustrated example.

  The chemical decolorization treatment includes bringing the polarizing film laminate into contact with a basic solution. The contact between the polarizing film laminate and the basic solution can be performed by any appropriate means. Typical examples include immersion of the polarizing film laminate in a basic solution, or application or spraying of a basic solution to the polarizing film laminate. Immersion is preferred. This is because, as will be described later, since the decoloring treatment can be performed while the polarizing film laminate is conveyed, the production efficiency is remarkably high. By using the first surface protective film (and the second surface protective film as necessary), immersion is possible. Specifically, the exposed portion of the polarizer is selectively brought into contact with the basic solution by being immersed in the basic solution. For example, when the polarizer contains iodine as a dichroic substance, the concentration of iodine at the contact portion of the polarizer with the basic solution is reduced by bringing the polarizer into contact with the basic solution. A non-polarizing part can be selectively formed only in the part (which can correspond to the exposed part). Thus, according to the present embodiment, the non-polarized portion can be selectively formed on the exposed portion with very high manufacturing efficiency without complicated operations. When iodine remains in the polarizer, even if the iodine complex is destroyed to form a non-polarizing part, the iodine complex is formed again with the use of the polarizer, and the non-polarizing part has the desired characteristics. There is a risk that it will disappear. In the present embodiment, iodine itself is removed from the polarizer (substantially the non-polarizing part) by removing the basic solution described later. As a result, it is possible to prevent a change in the characteristics of the non-polarizing part accompanying the use of the polarizer.

  The formation of the non-polarizing part by the basic solution will be described in more detail. After contact with a predetermined portion (exposed portion) of the polarizer, the basic solution penetrates into the predetermined portion. The iodine complex contained in the predetermined portion is reduced by the base contained in the basic solution to become iodine ions. When the iodine complex is reduced to iodine ions, the polarization performance of the part is substantially lost, and a non-polarizing part is formed in the part. Moreover, the transmittance | permeability of the said part improves by reduction | restoration of an iodine complex. Iodine that has become iodine ions moves from the portion into the solvent of the basic solution. As a result, by removing the basic solution described later, iodine ions are also removed from the portion together with the basic solution. In this way, a non-polarizing portion is selectively formed in the exposed portion, and the non-polarizing portion is stable without change over time. A portion where the basic solution is not desired by adjusting the material, thickness and mechanical properties of the first surface protective film, the concentration of the basic solution, and the immersion time of the polarizing film laminate in the basic solution, etc. (As a result, a non-polarizing part is formed in an undesired part) can be prevented.

  Any appropriate basic compound can be used as the basic compound contained in the basic solution. Examples of basic compounds 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, acetic acid Organic alkali metal salts such as sodium, aqueous ammonia and the like can be mentioned. The basic compound contained in the basic solution is preferably an alkali metal hydroxide, more preferably sodium hydroxide, potassium hydroxide, or lithium hydroxide. By using a basic solution containing an alkali metal hydroxide, the iodine complex can be ionized efficiently, and a non-polarizing part can be formed more easily. These basic compounds may be used alone or in combination of two or more.

  Any appropriate solvent can be used as the solvent of the basic solution. Specific examples include water, alcohols such as ethanol and methanol, ethers, benzene, chloroform, and mixed solvents thereof. Since iodine ions migrate to the solvent satisfactorily and iodine ions can be easily removed in the subsequent removal of the basic solution, the solvent is preferably water or alcohol.

  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 in such a range, the iodine concentration inside the polarizer can be efficiently reduced, and ionization of the iodine complex at a desired portion can be prevented. The pH of the basic solution is, for example, 10 or more.

  The liquid temperature of the basic solution is, for example, 20 ° C to 50 ° C. The contact time between the polarizing film laminate (substantially a predetermined part of the polarizer) and the basic solution depends on the thickness of the polarizer, the type of basic compound contained in the basic solution used, and the basic compound. For example, 5 seconds to 30 minutes.

  FIG. 4 is a schematic diagram illustrating a method for manufacturing a polarizer having a non-polarizing part according to an embodiment of the present invention. In the illustrated example, the polarizing film laminate 100 is immersed in a basic solution (decoloring bath A) while being conveyed in the longitudinal direction, and then immersed in a processing bath B maintained at pH 8 or lower. By immersing the polarizing film laminate 100 in such a treatment bath B, the basic solution is uniformly removed from the polarizing film laminate 100 (exposed portion 11). As a result, it is possible to prevent decoloring unevenness and form a uniform non-polarizing portion.

  The treatment bath B is provided with a supply means 1 for supplying a treatment liquid, a pH sensor 2 for measuring the pH of the treatment liquid, and a liquid level sensor 3 for measuring the liquid level of the treatment liquid. The supply means 1 includes an adjustment valve 6 provided at the supply port 5 to the treatment liquid source 4 and the treatment bath B. The opening and closing of the regulating valve 6 can be automatically controlled by the control device 7 to control the supply amount of the processing liquid. As automatic control, feedback control 7a may be employed. Specifically, based on the measurement signal from the pH sensor 2, when the pH of the treatment bath B rises, the adjustment valve 6 is released. On the other hand, in the pH sensor 2, when the pH reaches the predetermined value, the regulating valve 6 is closed. If necessary, the treatment liquid is discharged from the discharge port (not shown) of the treatment bath B when supplying the treatment liquid.

  Feedback control other than the above may also be employed. Specifically, based on the measurement signal from the liquid level sensor 3, the control device 7 releases the regulating valve 6 so that the liquid level becomes a predetermined height. By controlling the liquid level of the treatment bath, the immersion time of the polarizing film laminate in the treatment bath can be made uniform. As a result, a more uniform non-polarizing part can be formed. The pH and liquid level of the treatment bath B can be changed by bringing a basic solution into the treatment bath B, evaporation of the treatment bath B, or the like. When the polarizing film laminate and the basic solution are brought into contact with each other by immersion in a basic solution as shown in the drawing, the introduction of the basic solution into the treatment bath B can be significant.

  In one embodiment, the pH of the treatment bath B is maintained at 6 or higher. In this case, removal (washing) of the basic solution is mainly performed. In another embodiment, treatment bath B is kept below pH 6. In this case, the basic solution can be removed to a better level. Moreover, the dimensional stability and durability of the non-polarizing part to be formed can be improved.

  Examples of the treatment liquid for the treatment bath B include water (pure water), alcohols such as methanol and ethanol, acidic aqueous solutions, and mixed solvents thereof. Any appropriate acidic compound can be used as the acidic compound contained in the acidic solution. Examples of the acidic compound include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and hydrogen fluoride, and organic acids such as formic acid, oxalic acid, citric acid, acetic acid, and benzoic acid. The acidic compound contained in the acidic solution is preferably an inorganic acid, more preferably hydrochloric acid, sulfuric acid, or nitric acid. These acidic compounds may be used alone or in combination.

  As the solvent for the acidic solution, those exemplified as the solvent for the basic solution can be used. The density | concentration of the said acidic solution is 0.01N-5N, for example, Preferably it is 0.05N-3N, More preferably, it is 0.1N-2.5N.

  The liquid temperature of the said processing liquid is 20 to 50 degreeC, for example. The immersion time of the polarizing film laminate in the treatment liquid can be appropriately set. For example, it can be set according to the thickness of the polarizer, the type and concentration of the treatment liquid, and the like. Specifically, it is 5 seconds to 30 minutes.

  The immersion in the treatment bath may be performed in one stage or in multiple stages. When performing in multiple stages, the conditions (specifically, pH, concentration, liquid temperature, immersion time, etc.) of each treatment bath can be set for each. FIG. 5 is a schematic view illustrating a method for manufacturing a polarizer having a non-polarizing part according to another embodiment of the present invention. In the illustrated example, the polarizing film laminate 100 is immersed in a basic solution (decoloring bath A) while being transported in the longitudinal direction, and then sequentially immersed in the processing bath B1, the processing bath B2, and the processing bath B3. The pH of the treatment bath B1 is kept at 6 or more and 8 or less, and mainly the basic solution attached to the polarizing film laminate 100 can be removed. The pH of the treatment bath B2 is kept below 6, and in addition to the removal of the basic solution, the dimensional stability and durability of the formed non-polarizing part can be improved. The pH of the treatment bath B3 is maintained at 6 or more and 8 or less, and the treatment liquid of the treatment bath B2 attached to the polarizing film laminate 100 can be mainly removed (washed).

  Although not shown, after the immersion in the treatment bath, the liquid attached to the polarizing film laminate can be removed by, for example, blowing with a blower, contact with the absorber, suction, or the like. In addition, after immersion in the treatment bath, the polarizing film laminate can be subjected to a drying treatment. Drying is performed by conveying a polarizing film laminated body in oven, for example. The drying temperature is, for example, 20 ° C to 100 ° C. The drying time is, for example, 5 seconds to 600 seconds.

  The transmittance of the non-polarizing part (for example, transmittance measured with light having a wavelength of 550 nm at 23 ° C.) is preferably 50% or more, more preferably 60% or more, and further preferably 75% or more. Particularly preferably, it is 90% or more. With such transmittance, desired transparency as a non-polarizing portion can be ensured. As a result, for example, when the polarizer is arranged so that the non-polarizing part corresponds to the camera part of the image display device, it is possible to prevent an adverse effect on the photographing performance of the camera.

  The polarizer having a non-polarizing portion of the present invention is suitably used for 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.

DESCRIPTION OF SYMBOLS 10 Polarizer 11 Exposed part 20 Surface protective film (1st surface protective film)
30 Protective film 40 Second surface protective film 100 Polarizing film laminate

Claims (2)

An elongated polarizer and a surface protective film having a through hole disposed on one side of the polarizer, and having an exposed portion where the polarizer is exposed on the one side defined by the through hole Including contacting the polarizing film laminate with a basic solution, and immersing the polarizing film laminate in a treatment bath maintained at a pH of 8 or lower while conveying the polarizing film laminate in the longitudinal direction,
The exposed portions are arranged at intervals corresponding to the size of the polarizer to be cut in the longitudinal direction and / or the width direction of the elongated polarizing film laminate , and have a substantially circular plan view shape. ,
Measuring the pH or liquid level of the treatment bath, and feedback-controlling the supply amount of the treatment liquid to be supplied to the treatment bath based on the measured signal.
A method for producing a polarizer having a non-polarizing part. The manufacturing method according to claim 1, wherein the contact is performed by immersing the polarizing film laminate in a basic solution.

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