KR20220057594A - Method of manufacturing a polarizing plate - Google Patents

Abstract

[Problem] A method for manufacturing a polarizing plate in which cracks are suppressed in a heat shock test that repeats low-temperature (-40°C) and high-temperature (85°C) conditions, and iodine loss does not occur in the region including the end portion to provide.
[Solution] A first lamination process of bonding an optical film to at least one side of a polarizer having a thickness of 15 µm or less to produce a first laminate, and a first laminate at a temperature of 35°C or higher, relative humidity of 75% RH or higher The manufacturing method of the polarizing plate including the humidification process hold|maintained in gaseous phase.

Description

Method of manufacturing a polarizing plate

The present invention relates to a method for manufacturing a polarizing plate, and also to a polarizer, a polarizing plate, and an image display device including the same.

The method of manufacturing the light polarizer in which the site|part with a low boric-acid density|concentration was formed in the edge part is proposed by making patent document 1 contact a light polarizer with a process liquid 50 degreeC or more.

Patent Document 1: Japanese Patent Laid-Open No. 2016-206641

In the manufacturing method described in patent document 1, in the planar view of the part which made the polarizer 50 degreeC or more contacting a process liquid, over the edge part and the whole area|region between the edge part to 50 micrometers or more, a site|part with a low concentration of boric acid is formed, and iodine loss is occurring at the end and at a width exceeding 300 μm from the end.

An object of the present invention is a polarizing plate in which cracks are suppressed in a heat shock test that repeats low-temperature (-40°C) and high-temperature (85°C) conditions, and iodine leakage does not occur in the region including the end portion To provide a method for manufacturing Another object of the present invention is to provide a polarizer in which cracks are suppressed and iodine loss is not generated in the region including the edge portion, and a polarizing plate containing the polarizer.

This invention provides the manufacturing method of the following polarizing plate, a polarizer, a polarizing plate, and an image display apparatus.

[1] A method for manufacturing a polarizing plate, comprising:

A first lamination step of bonding an optical film to at least one side of a polarizer having a thickness of 15 μm or less to produce a first laminate;

The humidification treatment process which maintains a 1st laminated body in the gaseous phase of 75% RH or more of relative humidity in the temperature of 35 degreeC or more.

A method of manufacturing a polarizing plate comprising a.

[2] The method for producing a polarizing plate according to [1], further comprising a molding step of molding the first laminate before the humidification treatment step.

[3] The manufacturing method of the polarizing plate as described in [2] which forms a mold part in the said 1st laminated body in the said shaping|molding process.

[4] The method for producing a polarizing plate according to [2] or [3], further comprising a cutting step of cutting the first laminate before the humidifying treatment step.

[5] In the above-mentioned cutting step, in [4], cutting the first laminate so that the position of the end of the optical film and the position of the end of the polarizer are the same in the planar view of the first laminate The manufacturing method of the described polarizing plate.

[6] A polarizer comprising a resin film containing boric acid and iodine and having a thickness of 15 µm or less,

In the region including the end portion of the polarizer, it has a region containing boric acid at a concentration lower than the concentration of boric acid in regions other than this region;

The polarizer with which iodine loss|omission has not generate|occur|produced in the area|region including the edge part of the said polarizer.

[7] A polarizing plate comprising the polarizer according to [6] and an optical film bonded to at least one of the polarizers.

[8] The polarizing plate according to [7], wherein the position of the end of the polarizer and the position of the end of the optical film are the same at the end of the polarizing plate in plan view.

[9] An image display device provided with the polarizing plate according to [8].

[10] The image display device according to [9], having a camera hole.

According to the present invention, a polarizing plate in which cracks are suppressed in a heat shock test that repeats low-temperature (-40°C) conditions and high-temperature (85°C) conditions, and iodine loss does not occur in the region including the end portions. can provide a manufacturing method. In addition, according to the present invention, cracks are suppressed in a heat shock test (hereinafter also referred to as a heat shock test for simplicity) that repeats a low temperature (-40 ° C) condition and a high temperature (85 ° C) condition, A polarizer in which iodine loss has not occurred in the region, and a polarizing plate containing the polarizer can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows the polarizer by one Embodiment of this invention.
2 is a schematic diagram illustrating an example of a first laminate.
3 is a schematic top view of a polarizer for explaining a boric acid low concentration site.
4 is a schematic cross-sectional view showing an example of an image display device having a camera hole.
5 is a schematic view showing an example of a second laminate and an end mill.
6 is a schematic diagram illustrating an example of a cutting process.
7 is a schematic plan view showing a polarizing plate according to an embodiment of the present invention.
8 is a schematic plan view showing a polarizing plate according to an embodiment of the present invention.
9 is a schematic plan view showing a polarizing plate according to an embodiment of the present invention.
10 is a schematic cross-sectional view showing a polarizing plate according to an embodiment of the present invention.
It is a schematic for demonstrating the measurement sample in an Example.
12 shows the TOF-SIMS analysis result of the polarizing plate of Example 2.
13 shows the end observation result of the polarizing plate of Example 2. FIG.
14 shows the end observation result of the polarizing plate of Comparative Example 3. FIG.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described, referring drawings, this invention is not limited to the following embodiment. In all the drawings below, the scales are appropriately adjusted for easy understanding of each component, and the scale of each component shown in the drawings does not necessarily coincide with the scale of the actual component. In the drawings, equivalent components are denoted by equivalent reference numerals. X, Y, and Z shown in each figure mean three coordinate axes orthogonal to each other. The directions indicated by each of the XYZ coordinate axes in each figure are common to each figure.

<Method for producing a polarizing plate>

A method for manufacturing a polarizing plate according to an embodiment of the present invention includes a first lamination step of bonding an optical film to at least one side of a polarizer having a thickness of 15 μm or less to produce a first laminate, and the first laminate at a temperature of 35 It includes a humidification treatment process maintained in a gas phase at a relative humidity of 75% RH or higher at a temperature of not less than °C.

The polarizing plate obtained by the manufacturing method of a polarizing plate may have an optical film on both sides of a polarizer. As shown in FIG. 1 , in the polarizing plate 1 , the polarizer 2 is disposed between the first optical film 3 and the second optical film 4 . Hereinafter, a 1st optical film and a 2nd optical film may be generically called an optical film or a pair of optical films.

(1st lamination process)

At a 1st lamination|stacking process, a 1st laminated body is produced by overlapping a polarizer and an optical film and bonding together. The polarizer and the optical film may be in the form of a long strip. When the polarizer is overlapped so as to be disposed between a pair of optical films, as shown in FIG. 2 , in the first laminate 10 , the polarizer 7 includes the pair of first optical films 5 and the second It is located between the 2 optical films (9). The optical film can be bonded to the polarizer through an adhesive layer including an adhesive.

(polarizer)

The polarizer may be, for example, a polarizer in which iodine is oriented by adsorption to a uniaxially stretched polyvinyl alcohol-based resin film, and polyvinyl alcohol molecular chains are crosslinked with boric acid.

The polarizer may be an absorption type polarizer having a property of absorbing linearly polarized light having an oscillation plane parallel to the absorption axis and transmitting linearly polarized light having an oscillation plane perpendicular to the absorption axis (parallel to the transmission axis).

A polarizer can be manufactured, for example by giving an extending|stretching process, a dyeing|staining process, and a crosslinking process to a polyvinyl alcohol-type resin film (henceforth a PVA film). The stretching treatment, the dyeing treatment and the crosslinking treatment can be performed by a known method. A long strip|belt shape may be sufficient as a polyvinyl alcohol-type resin film, and single-leaf shape may be sufficient as it.

For example, first, a PVA film is extended|stretched in a uniaxial direction or a biaxial direction. The dichroic ratio of the polarizer stretched in the uniaxial direction tends to be high. Following stretching, using a dyeing solution, the PVA film is dyed with iodine, a dichroic dye (polyiodine) or an organic dye. The dyeing solution may contain boric acid, zinc sulfate, or zinc chloride. Before dyeing, the PVA film may be washed with water. By washing with water, dirt and antiblocking agent are removed from the surface of the PVA film. Moreover, as a result of a PVA film swelling by water washing, it is easy to suppress the unevenness of dyeing (non-uniform dyeing|dyeing). The PVA film after dyeing is treated with a solution of a crosslinking agent containing boric acid (eg, aqueous solution of boric acid) for crosslinking. After treatment with a crosslinking agent, the PVA film is washed with water and subsequently dried. The polarizer containing the resin film containing boric acid and an iodine is obtained through the above procedure. Polyvinyl alcohol (PVA)-type resin is obtained by saponifying polyvinyl acetate-type resin. The polyvinyl acetate-based resin may be, for example, polyvinyl acetate, which is a homopolymer of vinyl acetate, or a copolymer of vinyl acetate and another monomer (eg, ethylene-vinyl acetate copolymer). The other monomer copolymerized with vinyl acetate may be, other than ethylene, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, or acrylamides having an ammonium group. The polyvinyl alcohol-based resin may be modified with aldehydes. The modified polyvinyl alcohol-based resin may be, for example, partially formalized polyvinyl alcohol, polyvinyl acetal, or polyvinyl butyral. The polyvinyl alcohol-based resin may be a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride. You may dye|stain before extending|stretching, and you may extend|stretch in a dyeing solution. The length of the stretched resin film may be, for example, 3 to 7 times the length before stretching.

The thickness of the polarizer may be, for example, 15 µm or less, preferably 10 µm or less, and more preferably 8 µm or less. The thickness of the polarizer is usually 1 µm or more, and for example, 3 µm or more may be sufficient. As the polarizer is thinner, the shrinkage or expansion of the polarizer itself with a change in temperature tends to be suppressed, and the change in the dimension of the polarizer itself tends to be easily suppressed. As a result, stress becomes difficult to act on a polarizer, and there exists a tendency for the crack in a polarizer to become suppressed easily.

(optical film)

The optical film may be a translucent thermoplastic resin. The optical film may be an optically transparent thermoplastic resin. The resin constituting the optical film is, for example, a chain polyolefin-based resin, a cyclic olefin polymer-based resin (COP-based resin), a cellulose ester-based resin, a polyester-based resin, a polycarbonate-based resin, ( A meth)acrylic resin, a polystyrene-type resin, or these mixtures or copolymers may be sufficient.

When a polarizing plate has a 1st optical film and a 2nd optical film, the composition of a 1st optical film may be completely the same as the composition of a 2nd optical film. For example, both a 1st optical film and a 2nd optical film may contain cyclic olefin polymer type resin (COP type resin). When a 1st optical film and a 2nd optical film contain cyclic olefin polymer-type resin (COP-type resin), the effect of this invention is easy to be acquired. When a polarizing plate has a 1st optical film and a 2nd optical film, the composition of a 1st optical film may differ from a composition of a 2nd optical film.

It is preferable that the glass transition temperatures of a 1st optical film and a 2nd optical film are 100 degrees C or more and 200 degrees C or less, or 120 degrees C or more and 150 degrees C or less. When the glass transition temperature of each of the first optical film and the second optical film is within the above range, the first optical film and the second optical film are likely to be fused to each other by the heat generated by the polishing of the end of each optical film.

The chain polyolefin resin may be, for example, a homopolymer of a chain olefin such as a polyethylene resin or a polypropylene resin. The chain polyolefin resin may be a copolymer containing two or more kinds of chain olefins.

The cyclic olefin polymer resin (cyclic polyolefin resin) may be, for example, a ring-opened (co)polymer of a cyclic olefin or an addition polymer of a cyclic olefin. The cyclic olefin polymer resin may be, for example, a copolymer of a cyclic olefin and a chain olefin (eg, a random copolymer). The chain olefin constituting the copolymer may be, for example, ethylene or propylene. The cyclic olefin polymer-type resin may be the graft polymer which modified|denatured the said polymer with unsaturated carboxylic acid or its derivative(s), or these hydrides may be sufficient as it. Norbornene-type resin using norbornene-type monomers, such as norbornene or a polycyclic norbornene-type monomer, may be sufficient as cyclic olefin polymer-type resin, for example.

Cellulose ester resin may be, for example, cellulose triacetate (triacetyl cellulose (TAC)), cellulose diacetate, cellulose tripropionate, or cellulose dipropionate. You may use these copolymers. You may use the cellulose ester-type resin by which a part of hydroxyl group was modified by the other substituent.

You may use polyester-type resin other than cellulose-ester-type resin. The polyester resin may be, for example, a polycondensate of a polyhydric carboxylic acid or a derivative thereof and a polyhydric alcohol. Dicarboxylic acid or its derivative(s) may be sufficient as polyhydric carboxylic acid or its derivative(s). The polyhydric carboxylic acid or its derivative may be, for example, terephthalic acid, isophthalic acid, dimethyl terephthalate, or dimethyl naphthalenedicarboxylic acid. The polyhydric alcohol may be, for example, a diol. The polyhydric alcohol may be, for example, ethylene glycol, propanediol, butanediol, neopentyl glycol, or cyclohexanedimethanol.

The polyester-based resin is, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate, or polycyclohexane. Dimethyl naphthalate may be sufficient.

The polycarbonate-based resin is a polymer in which a polymerization unit (monomer) is bonded through a carbonate group. The polycarbonate-based resin may be a modified polycarbonate having a modified polymer skeleton, or may be a copolymerized polycarbonate.

The (meth)acrylic resin is, for example, poly(meth)acrylic acid ester (eg, polymethyl methacrylate (PMMA)); methyl methacrylate-(meth)acrylic acid copolymer; methyl methacrylate-(meth)acrylic acid ester copolymer; methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymer; (meth) methyl acrylate-styrene copolymer (eg, MS resin); A copolymer of methyl methacrylate and a compound having an alicyclic hydrocarbon group (eg, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-(meth) acrylate norbornyl copolymer, etc.) may be sufficient.

Each of the first optical film or the second optical film contains at least one additive selected from the group consisting of a lubricant, a plasticizer, a dispersant, a heat stabilizer, an ultraviolet absorber, an infrared absorber, an antistatic agent, and an antioxidant. good to do

The thickness of the first optical film may be, for example, 5 µm or more and 90 µm or less, or 10 µm or more and 60 µm or less. The thickness of the second optical film may also be, for example, 5 µm or more and 90 µm or less, or 10 µm or more and 60 µm or less.

The film which has an optical function may be sufficient as at least one of a 1st optical film and a 2nd optical film. The film having an optical function may be, for example, a retardation film or a brightness improving film. For example, the retardation film to which arbitrary retardation values were provided is obtained by extending|stretching the film containing the said thermoplastic resin, or forming a liquid crystal layer etc. on the said film.

The 1st optical film may be superimposed on a polarizer via a contact bonding layer. The 2nd optical film may also be superimposed on the opposite side to the 1st optical film of a polarizer via a contact bonding layer. The adhesive layer may contain a water-based adhesive such as polyvinyl alcohol. The contact bonding layer may also contain the active energy ray-curable resin mentioned later.

Active energy ray-curable resin is resin hardened|cured by irradiating an active energy ray. The active energy ray may be, for example, ultraviolet light, visible light, electron beam, or X-ray. For example, ultraviolet curable resin may be sufficient as active energy ray-curable resin.

One type of resin may be sufficient as active energy ray-curable resin, and may also contain multiple types of resin. For example, active energy ray-curable resin may contain a cationically polymerizable sclerosing|hardenable compound, or a radically polymerizable sclerosing|hardenable compound. Active energy ray-curable resin may also contain the cationic polymerization initiator or radical polymerization initiator for starting the hardening reaction of the said sclerosing|hardenable compound.

The cationically polymerizable curable compound may be, for example, an epoxy compound (a compound having at least one epoxy group in its molecule) or an oxetane compound (a compound having at least one oxetane ring in its molecule). The radically polymerizable sclerosing compound may be, for example, a (meth)acrylic compound (a compound having at least one (meth)acryloyloxy group in its molecule). The radically polymerizable sclerosing|hardenable compound may be a vinyl-type compound which has a radically polymerizable double bond.

The active energy ray-curable resin is, if necessary, a cationic polymerization accelerator, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, an antifoaming agent, an antistatic agent, a leveling agent, or a solvent. may include

(humidification treatment process)

A humidification process is performed by hold|maintaining a 1st laminated body in the gaseous phase of 75 %RH or more of relative humidity in the temperature of 35 degreeC or more. According to the humidification treatment, in the region including the end portion of the first laminate, a region containing boric acid at a concentration lower than the concentration of boric acid in regions other than this region (hereinafter also referred to as a low boric acid content region) is formed In spite of this, iodine loss does not occur and linearly polarizing ability is exhibited even in a region with a low boric acid content. The polarizing plate manufactured by the manufacturing method of this invention does not generate|occur|produce a crack also in a heat shock test, but can exhibit linearly polarizing ability also in the area|region including an edge part.

As patent document 1 describes, in order to suppress generation|occurrence|production of a crack in a heat shock test, it is known that it is effective to make low the density|concentration of the boric acid contained in the edge part of a polarizer. However, in the manufacturing method of patent document 1, boric acid is removed over the whole area between 50 micrometers or more from the edge part and edge part of polarizer, As a result, the whole area of the width exceeding 300 micrometers from the edge part and edge part of light polarizer. It turned out that iodine loss|extraction generate|occur|produced over this and it became impossible to exhibit linearly polarizing ability in the edge part. However, according to the manufacturing method of this invention, it is only the excess boric acid contained in the edge part of a polarizer that is removed by performing the humidification process hold|maintained in the gaseous phase of 75% RH or more of relative humidity at a temperature of 35 degreeC or more, and iodine loss occurs. Since there exists a tendency which it is difficult to do, generation|occurrence|production of a crack is suppressed in a heat shock test, and the polarizing plate obtained can exhibit linearly polarizing ability also in an edge part.

The concentration of boric acid refers to the concentration of boric acid per unit area including the thickness direction of the polarizing plate, and is measured by, for example, time-of-flight secondary ion mass spectrometry (TOF-SIMS) described in the section of Examples to be described later. In the present specification, boric acid includes, for example, a molecule of boric acid (H ₃ BO ₃ ) and a boric acid ion (BO ₃ ^3- ).

The region in which iodine depletion has occurred (hereinafter also referred to as iodine depleted region) is a region observed with the naked eye as a region through which light is transmitted in a cross nicol state using a polarization microscope. Iodine includes, for example, an iodine molecule (I ₂ ), a polyiodine complex (I ₃ ⁻ , I ₅ ⁻ ), and an iodine ion (I ⁻ ).

In this specification, planar view means seeing from the thickness direction of a polarizing plate.

The temperature of the gas phase is 35°C or higher. When the temperature of a gas phase is 35 degreeC or more, there exists a tendency for the excess boric acid contained in the edge part of a polarizing plate to become easy to remove. The temperature of the gas phase is preferably 40°C or higher from the viewpoint of easily removing boric acid. The temperature of the gas phase may be, for example, 90°C or lower, and preferably 85°C or lower. When the temperature of gas phase is 90 degrees C or less, there exists a tendency for iodine loss to become difficult to generate|occur|produce. The temperature of the gas phase can be adjusted within the above range so that excess boric acid is removed at the edge of the polarizer and iodine loss does not occur.

The relative humidity of the weather is at least 75% RH. When a relative humidity is 75 %RH or more, there exists a tendency for the excess boric acid contained in the edge part of a polarizing plate to become easy to remove. The relative humidity of the gas phase is preferably 80% RH or more from the viewpoint of easily removing boric acid. The relative humidity of the gas phase may be, for example, 90% RH or less, preferably 85% RH or less. When the relative humidity of the gas phase is 90% RH or less, iodine loss tends to be difficult to occur. The relative humidity of gaseous phase can be adjusted within the said range so that excess boric acid may be removed in the edge part of a polarizer, and iodine loss may not generate|occur|produce.

The time period for performing the humidification treatment may be, for example, 0.5 hours or more and 4 hours or less, preferably 1 hour or more and 3 hours or less, more preferably 1.5 hours or more and 2.5 hours or less, from the viewpoint of easy removal of boric acid and prevention of iodine loss. am. In addition, the humidification process is normally performed continuously for said time.

The humidification process can be performed using, for example, a constant-temperature and constant-humidity furnace.

When the first laminate has a mold release portion described later, cracks are suppressed and iodine leakage is less conspicuous. Preferably, the humidification treatment is performed so that the end region included in the release portion is humidified.

From the viewpoint of suppressing cracks and making iodine loss less conspicuous in the appearance of the polarizing plate, the humidification treatment is preferably performed so that the concentration of boric acid in the low boric acid content region is inward from the end of the polarizing plate. It can be performed so that a density|concentration which becomes higher as it increases can be obtained. Such a concentration tends to be easily obtained when the temperature of the gas phase is lowered, the relative humidity is lowered, or the time for the humidification treatment is shortened under the conditions of the humidification treatment.

The low boric acid content region may be formed, for example, in a region exceeding 15 µm in the inward direction from the end in a planar view of the polarizing plate, and is preferably formed in an area exceeding 15 µm and less than 200 µm from the viewpoint of crack suppression, , more preferably in an area of 20 µm or more and 150 µm or less, still more preferably in an area of 20 µm or more and less than 100 µm, particularly preferably in a region of 20 µm or more and less than 50 µm.

The boric acid low content area|region may be formed also in the area|region 15 micrometers or less from the edge part in planar view of a polarizing plate.

The low boric acid content region is continuously formed in the entire region of 15 µm or less from the end of the polarizing plate in plan view and the entire region of more than 15 µm and less than 200 µm in the inward direction from the end of the polarizing plate in plan view, good to be In other words, the boric acid low content region may be formed over the entire region between the end portion and the end portion of the polarizing plate in a plan view of less than 200 µm. When the boric acid low content region is formed over the entire region between the end portion and the end portion less than 200 μm in plan view of the polarizing plate, the boundary between the boric acid low acid content region and the other region is less than 200 μm between the edge portion and the end portion. may exist in the realm of

The low boric acid content region is preferably formed over the entire area between the end and the end of the polarizing plate 100 µm or less in plan view, and more preferably 50 µm or less from the end and the end in the plan view of the polarizing plate. It is formed over the entire region between the polarizing plates, and more preferably, it is formed over the entire region between the end portion and the end portion of the polarizing plate in a plane view of 20 µm or less.

The edge part of a polarizing plate does not need to contain boric acid.

The boundary between the region in which the low boric acid content region is formed and the other regions is, for example, a boric acid concentration profile with respect to the distance from the end obtained by the time-of-flight secondary ion mass spectrometry (TOF-SIMS) described in the section of Examples to be described later. can be obtained from For example, if a region with a constant boric acid ion strength can be read in the boric acid concentration profile, the average value of the boric acid ion strength of that region is obtained, and the position from the end to the position where the boric acid ion strength becomes the average value is defined as the low boric acid concentration region. can do. If the region where the boric acid ion strength is constant is difficult to read in the boric acid concentration profile, the average value of the boric acid ion strength in the range of 30 µm inward from the point where the boric acid ion strength is the maximum in the boric acid concentration profile is obtained, , from the end to the position at which the boric acid ion strength becomes the above average value can be defined as the low boric acid concentration site.

One continuous area|region may be sufficient as a boric-acid low content area|region in the planar view of a polarizing plate, and the area|region divided into plurality may be sufficient as it.

The boric acid low content region is preferably formed along the outer edge of the polarizing plate from the viewpoint of crack suppression. The boric acid low content region may be formed along the entire outer edge of the polarizing plate, or may be formed along a part of the outer edge of the polarizing plate.

By performing such a humidification process, the edge part in the planar view of a polarizer WHEREIN: The light polarizer which has a region containing boric acid at a lower concentration than the density|concentration of boric acid in regions other than this region is obtained. This polarizer is specifically, a polarizer in which the boric-acid low concentration site|part which is a density|concentration of boric acid lower than the density|concentration of boric acid in the inner side region 500 micrometers or more from an edge part was formed. In the inner region, the concentration of boric acid may be approximately the same. The polarizer 2 shown in FIG. 3 has the boric acid low concentration site|part 30 in the area|region including the edge part in planar view, and can have the inner side area|region 32 inside 500 micrometers or more from an edge part. The inner region 32 may include a region for displaying an image when incorporated in a liquid crystal display device. The boric acid concentration in the intermediate|middle area|region 31 between the boric-acid low concentration site|part 30 and the inner side area|region 32 is a boric-acid concentration substantially the same as that of the inner side area|region 32 normally. Moreover, in the edge part in the planar view of a polarizer by performing this humidification process, the polarizer in which iodine loss has not generate|occur|produced is obtained. This polarizer is specifically, a polarizer in which the low iodine concentration site|part which is the density|concentration of iodine lower than the density|concentration of iodine in the said inner region is not formed.

(Forming process)

The manufacturing method of a polarizing plate may further include the shaping|molding process of shaping|molding a 1st laminated body before a humidification process process. In the molding step, the first laminate can be molded into a predetermined shape by cutting and/or punching processing. Cutting and/or punching processing can be performed by using a cutter or irradiating a laser beam. The laser beam may be a CO ₂ laser.

As for the 1st laminated body, the dimension of a 1st laminated body may be adjusted to the dimension which is easy to process by a shaping|molding process. Moreover, you may form a mold release part in the outer edge part of a 1st laminated body by a punching process or a cutting process. The mold release portion may be, for example, a concave portion formed on the outer edge portion, a substantially V-shaped portion convex inwardly, and a through hole formed in the surface of the first laminate in a plan view. The 1st laminated body may have two or more mold release parts in an outer edge part and/or surface. The through hole formed in the surface may be the camera hole or the like described above.

The polarizing plate which has a mold release part is a heat shock test. WHEREIN: Stress tends to concentrate on a mold part part, and there exists a tendency for a crack to generate|occur|produce easily. Although the polarizing plate of this invention has a mold release part, it exists in the tendency which becomes easy to suppress generation|occurrence|production of a crack in a heat shock test by forming a boric-acid low content area|region in the edge part area|region of a mold release part.

The polarizing plate manufactured by the manufacturing method of this invention is suitable for the image display apparatus which has a camera hole, for example. As shown in FIG. 4 , a camera hole 22 , a cover glass 24 , an adhesive layer 25 , a polarizing plate 21 , a liquid crystal panel 23 , a polarizing plate 26 , a camera 27 , and a light-shielding tape In the image display device 20 having (28), in the figure, the portion forming the camera hole surrounded by a circle is easily visually recognized. When iodine omission generate|occur|produces in such a part, iodine omission will become conspicuous, and as a result, the fall of design may be caused. However, in the polarizing plate of the present invention, since iodine leakage does not occur in the region including the edge portion, even when it is disposed on the visual recognition side in an image display device, iodine leakage is difficult to be conspicuous, and a decrease in design occurs. hard to do

When the deformable portion is a concave portion, it is preferably formed such that the depth direction of the concave portion and the absorption axis (stretching axis direction) are orthogonal to each other from the viewpoint of crack suppression. Further, the concave portion may be formed so that the depth direction thereof intersects the absorption axis (stretch axis direction) at an angle of usually 30° or more and 60° or less.

(cutting process)

The manufacturing method of the polarizing plate may further include a cutting process of bringing the end mill into contact with the outer periphery of the first laminate or the second laminate to be described later, and moving the end mill along the outer periphery of the laminate before the humidification treatment process. . As shown in FIG. 2 , the positions of the ends of the polarizer 7 and the first optical film 5 and the second optical film 9 all over the outer periphery of the first laminate 10 before the cutting process coincide it's fine to do

5 and 6 , the end mill 50 used in the cutting process has a blade (edge) 50e protruding from a side surface substantially parallel to the rotation axis 50a thereof. In the cutting process, the side surface of the end mill 50 is brought into contact with the outer periphery (end surface) of the first laminate 10 , and the rotating end mill 50 is moved along the outer periphery of the first laminate 10 . . For example, you may move the rotating end mill 50 along the path|route indicated by the arrow in FIG. As a result, the outer periphery (end surface) of the first laminate 10 is cut or polished by the blade 50e, the outer periphery (end surface) of the first laminate 10 becomes smooth, and the concave portion 13 ) is formed, and the inner corner of the concave shape 13 is chamfered. As shown in FIG. 5 , after overlapping a plurality of first laminates 10 to form a second laminate 100 , the side surface of the end mill 50 is placed on the outer periphery of the second laminate 100 ( end face) and the rotating end mill 50 may be moved along the outer periphery of the second laminate 100 . That is, in a cutting process, you may cut or grind|polish the outer periphery of the some 1st laminated body 10 which comprises the 2nd laminated body 100 collectively with the end mill 50. In a cutting process, each of the corner|angular part located at the both ends of the concave-shaped part 13, and the corner|angular part located at the four corners of the 1st laminated body 10 may be chamfered.

The cutting amount of the end mill in the cutting step may be, for example, 10 µm or more and 500 µm or less, and preferably 50 µm or more and 150 µm or less.

The cutting process may be repeated three or more times. For example, in the 3rd cutting process, you may remove the 1st laminated body 10 from the end face of the 1st laminated body 10 almost without cutting, and the cutting chips which generate|occur|produced in the 2nd cutting process. In each cutting process, you may use several end mills.

The feed rate of the end mill in the cutting process may be 100 mm/min or more and less than 3000 mm/min. The rotational speed of the end mill in the cutting step may be, for example, 500 rpm or more and 60000 rpm or less, and preferably 10000 rpm or more and 60000 rpm or less. The cutting angle in the cutting step may be, for example, 30° or more and 70° or less, and preferably 45° or more and 65° or less. When the torsion angle of the end mill 50 is α, the cutting angle β is defined as 90°-α. As shown in FIG. 6 , the torsion angle α of the end mill 50 is the direction d1 in which the blade 50e extends from the side surface of the end mill 50 and the rotation axis of the end mill 50 . It is the angle formed by (50a). In other words, the cutting angle β may be an angle formed between a direction d1 in which the blade 50e extends and a direction d2 perpendicular to the rotation axis 50a. The diameter (phi) (thickness) of the end mill 50 used for a cutting process may be 3.0 mm or more and 6.0 mm or less, for example.

By cutting in the state of a 1st laminated body or a 2nd laminated body, the planar view of a 1st laminated body or a 2nd laminated body WHEREIN: 1st lamination|stacking so that the position of the edge part of an optical film and the position of the edge part of a polarizer may become the same. The sieve or the second laminate can be cut. Therefore, the polarizing plate obtained can have linearly polarizing ability to the edge part of a polarizing plate in the edge part formed by cutting.

<Polarizer>

The polarizer according to another embodiment of the present invention includes a resin film containing boric acid and iodine, and is a polarizer having a thickness of 15 µm or less. The polarizer may be, for example, a polarizer in which iodine is oriented by adsorption to a uniaxially stretched polyvinyl alcohol-based resin film, and polyvinyl alcohol molecular chains are crosslinked with boric acid. The polarizer may be an absorption type polarizer having a property of absorbing linearly polarized light having an oscillation plane parallel to the absorption axis and transmitting linearly polarized light having an oscillation plane perpendicular to the absorption axis (parallel to the transmission axis).

The polarizer has a region containing boric acid at a concentration lower than the concentration of boric acid in regions other than the region (hereinafter also referred to as a low boric acid content region of the polarizer) in the region including the end portion of the polarizer, It is a polarizer in which iodine loss|omission has not generate|occur|produced in the area|region including an edge part. Therefore, in the polarizer of this invention, generation|occurrence|production of a crack is suppressed in a heat shock test, and can exhibit linearly polarizing ability also in an edge part.

The polarizer preferably has a concentration of boric acid in the low boric acid content region of the polarizer in the inner direction from the end of the polarizing plate from the viewpoint of suppressing cracks and making iodine loss less conspicuous in the appearance of the polarizer. It is getting higher and higher.

The low boric acid content region of the polarizer may be formed, for example, in a region exceeding 15 µm in the inward direction from the end in a planar view of the polarizer, and preferably a region exceeding 15 µm and less than 200 µm from the viewpoint of crack suppression. may be formed in the region, more preferably in a region of 20 µm or more and 150 µm or less, still more preferably in a region of 20 µm or more and less than 100 µm, particularly preferably 20 µm or more and 50 µm or less. It may be formed in the area|region of less than micrometer.

The boric acid low content area|region of a polarizer may be formed also in the area|region 15 micrometers or less from the edge part in planar view of a polarizer.

The boric acid low content region of the polarizer is continuous to the entire region of 15 µm or less from the end in the planar view of the polarizer and the entire region exceeding 15 µm and less than 200 µm in the inward direction from the end in the planar view of the polarizer. may be formed. In other words, the boric acid low content area|region of a polarizer may be formed over the edge part in planar view of a polarizer, and the whole area between less than 200 micrometers from an edge part. When the boric acid low content region of the polarizer is formed over the entire region less than 200 µm from the end portion and the end portion in a planar view of the polarizer, the boundary between the boric acid low content region of the polarizer and other regions is from the end portion and the end portion It may be present in the region between less than 200 μm.

The low boric acid content region of the polarizer is preferably formed over the entire region between the end and the end of the polarizer 100 µm or less in plan view, and more preferably 50 from the end and the end in the planar view of the polarizer. It is formed over the whole area between micrometers or less, More preferably, it forms over the edge part in the planar view of a polarizer, and the whole area between 20 micrometers or less from the edge part.

The edge part of a polarizer does not need to contain boric acid.

The boundary between the area|region in which the boric-acid low content site|part was formed, and the area|region other than that can be determined by the method described in the manufacturing method of the above-mentioned polarizing plate.

One continuous area|region may be sufficient as the boric-acid low content area|region of a polarizer in planar view of a polarizer, and the area|region divided into plurality may be sufficient as it.

The low boric acid content region of the polarizer is preferably formed along the outer edge of the polarizer from the viewpoint of suppressing cracks. The boric acid low content region may be formed along the entire outer edge of the polarizer, or may be formed along a part of the outer edge of the polarizer.

Specifically, the boric acid low content region of the polarizer may have a boric acid concentration lower than the boric acid concentration in the inner region 500 µm or more inside from the end portion. In the inner region, the concentration of boric acid may be approximately the same. As shown in FIG. 3, the polarizer may have the boric-acid low concentration site|part 30 in the area|region including the edge part in planar view, and may have the inner side area|region 32 500 micrometers or more inside from the edge part. The inner region 32 may include a region for displaying an image when incorporated in a liquid crystal display device. The boric acid concentration in the intermediate|middle area|region 31 between the boric-acid low concentration site|part 30 and the inner side area|region 32 is a boric-acid concentration substantially the same as that of the inner side area|region 32 normally. In addition, the polarizer in which iodine loss|extraction has not generate|occur|produced is specifically, the polarizer in which the low iodine concentration site|part which is a density|concentration of iodine lower than the density|concentration of iodine in the said inner region is not formed. The presence or absence of the low iodine concentration site|part can be confirmed by the method of measuring in the column of the Example mentioned later.

As for the illustration and preferable range of the thickness of a polarizer, the illustration and preferable range in description of the manufacturing method of the above-mentioned polarizing plate apply.

The polarizer may provide a mold release part in the outer edge part. The deformable portion may be, for example, a concave portion formed on the outer edge portion, a substantially V-shaped portion convex in the inward direction, and a through hole formed in the plane in a planar view of the polarizer. The polarizer may have two or more deformable parts in an outer edge part and/or surface. The through hole formed in the surface may be the camera hole or the like described above. Since the polarizer does not cause iodine loss in the region including the edge portion, even when used for a polarizing plate disposed on the viewer side in an image display device, the iodine loss is difficult to be conspicuous and a decrease in design occurs. it's difficult.

The polarizer can be manufactured by, for example, subjecting a uniaxially stretched polyvinyl alcohol-based resin film containing boric acid and iodine to a humidifying treatment. The example and preferable range of the conditions of the humidification process demonstrated in the manufacturing method of the above-mentioned polarizing plate are applicable to the example and preferable range of the conditions of a humidification process.

<Polarizer>

The polarizing plate which concerns on another embodiment of this invention has the above-mentioned polarizer and the optical film bonded by at least one side of the polarizer. As for the example and preferable range of an optical film, the example and preferable range demonstrated in the manufacturing method of the above-mentioned polarizing plate apply.

As shown in FIG. 1 , the polarizing plate 1 according to the present embodiment is a film-type polarizer positioned between at least a pair of optical films 3 and 4 and a pair of optical films 3 and 4 . (2) is provided. Hereinafter, for convenience of description, the polarizing plate 1 composed of the polarizer 2 and a pair of optical films 3 and 4 is mainly described. However, the number of the optical films with which a polarizing plate is equipped is not limited to 2 sheets so that it may mention later.

An optical film means the film-shaped member (polarizer 2 itself is excluded.) which comprises the polarizing plate 1. For example, an optical film implies a protective film and a release film. Each optical film alone may not have a specific optical function. "Film" (optical film) may be replaced with "layer" (optical layer) in other words. Each of the pair of optical films 3 and 4 contains a resin. However, the composition of each of the optical films 3 and 4 is not limited. Each of the pair of optical films 3 and 4 contains a resin. However, the composition of each of the optical films 3 and 4 is not limited.

The polarizer 2 overlaps each of the optical films 3 and 4 directly or indirectly. For example, there may be another optical film between the polarizer 2 and the optical films 3 and 4 . The polarizer 2 may overlap each of the optical films 3 and 4 via an adhesive layer.

7 shows the surface (light-receiving surface) of the polarizing plate 1 according to the present embodiment. The cross section of the polarizing plate 1 shown in FIG. 7 is perpendicular to the surface (light-receiving surface) of the polarizing plate 1 and is orthogonal to the outer periphery 1p of the polarizing plate 1 located inside the recess 13 .

As shown in FIG. 7 , a recess 13 is formed on the outer periphery 1p of the polarizing plate 1 . That is, there is a concave portion 13 on the outer periphery 1p of the polarizing plate 1 . The concave portion 13 may be referred to as a depression, a cutout or a notch in other words. The recessed part 13 may penetrate the polarizing plate 1 in the direction (Z-axis direction) perpendicular|vertical to the surface (light-receiving surface) of the polarizing plate 1 . The outer periphery 1p of the polarizing plate 1 may be in other words the outer edge or outline of the polarizing plate 1 (light-receiving surface) viewed from a direction perpendicular to the light-receiving surface of the polarizing plate 1 .

The inner corner 13c of the concave portion 13 may be a curved surface. That is, the end surface of the polarizing plate 1 located in the inner corner 13c of the recessed part 13 may be a curved surface. That is, the corner 13c inside the recess may be chamfered. When the inner corner 13c of the concave portion 13 is a curved surface, cracks in the inner corner 13c of the concave portion 13 are easily suppressed. As shown in FIG. 7 , the corner portions located at both ends of the concave portion 13 and the corner portions located at the four corners of the polarizing plate 1 may also be chamfered.

Although the width|variety of the recessed part 13 (the width|variety of the recessed part 13 in X-axis direction) is not specifically limited, For example, 3 mm or more and 160 mm or less may be sufficient. Although the depth of the recessed part 13 (the width|variety of the recessed part 13 in a Y-axis direction) is not specifically limited, For example, 0.5 mm or more and 160 mm or less may be sufficient. Although the length of the side (short side) of the polarizing plate 1 in which the recessed part 13 is formed is not specifically limited, For example, 30 mm or more and 90 mm or less may be sufficient. Although the length of the side (long side) of the polarizing plate 1 in which the recessed part 13 is not formed is not specifically limited, For example, 30 mm or more and 170 mm or less may be sufficient.

Although the thickness of the whole polarizing plate 1 is not specifically limited, For example, 30 micrometers or more and 300 micrometers or less may be sufficient.

The concave portion 13 shown in Fig. 7 has a rectangular shape (rectangular shape). However, the shape of the recessed part 13 is not limited. For example, the concave portion 13 may have a square shape. The concave portion 13 may be a polygon other than a quadrangle and a triangle. For example, as shown in (a) in FIG. 8, the shape of the recessed part 13 may be a semicircle. As shown in (b) of FIG. 8, the shape of the recessed part 13 may be triangular. The entire concave portion 13 may be curved. The recessed part 13 may be comprised with a straight line and a curved line. Although the shape of the polarizing plate 1 shown to Fig.7, Fig.8 (a), and Fig.8 (b) all has symmetry, the shape of the polarizing plate 1 may be asymmetrical. A plurality of concave portions 13 may be formed in the outer periphery 1p of the polarizing plate 1 . The plurality of concave portions 13 may be formed on one side constituting the outer periphery 1p of the polarizing plate 1 . The concave portion 13 may be formed by cutting off at least one of the four corners of the rectangular polarizing plate 1 .

The overall shape of the polarizing plate 1 excluding the concave portion 13 is substantially rectangular (rectangular). However, the shape of the polarizing plate 1 is not limited. For example, the shape of the polarizing plate 1 may be square. The shape of the polarizing plate 1 may be polygons other than a quadrangle, a circle, or an ellipse. The overall shape of each of the polarizer 2 and the optical films 3 and 4 may be substantially the same as the shape of the polarizing plate 1 . In the case of the rectangular polarizing plate 1 shown in FIG. 6 , the concave portion 13 is formed on the short side of the polarizing plate 1 , but the concave portion 13 is formed on the long side of the polarizing plate 1 . good.

As shown in FIG. 9, the polarizing plate 1 may have a through-hole in plane in planar view. The diameter of the through hole may be, for example, 0.5 mm or more and 30 mm or less, and preferably 1 mm or more and 10 mm or less.

(Another embodiment of a polarizing plate)

For example, in addition to a pair of optical films containing a 1st optical film and a 2nd optical film, a polarizing plate may further be equipped with the other optical film containing resin. That is, the polarizing plate may be equipped with 3 or more optical films. For example, as shown in FIG. 10 , the polarizer is positioned between the first optical film 3 and the second optical film 4 , and the first optical film 3 and the second optical film 4 . (2) and the 3rd optical film 15 which overlaps with the 1st optical film 3 may be provided. The 3rd optical film 15 may be superimposed on the 1st optical film 3 via the adhesive layer mentioned above. The resin contained in the third optical film 15 may be at least any one of the above-described resins listed as the resin contained in each of the first optical film 3 and the second optical film 4 . The composition of the third optical film 15 may be the same as the composition of the first optical film 3 . The composition of the 3rd optical film 15 may differ from the composition of the 1st optical film 3 .

The composition of the 3rd optical film 15 may be the same as the composition of the 2nd optical film 4 . The composition of the 3rd optical film 15 may differ from the composition of the 2nd optical film 4 . The thickness of the 3rd optical film 15 may be 5 micrometers or more and 200 micrometers or less, for example. In the manufacturing process of an image display apparatus, the 3rd optical film 15 peels from a polarizing plate, and may be removed. That is, the 3rd optical film 15 may be a temporary optical film.

A polarizing plate may further be equipped with the adhesive layer which overlaps on one of a pair of optical films, and the release film which overlaps with the adhesion layer. For example, the polarizing plate shown in FIG. 10 may further be equipped with the adhesive layer which overlaps with the 2nd optical film 4, and the release film which overlaps with the adhesive layer. The pressure-sensitive adhesive layer may include, for example, a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, or a urethane pressure-sensitive adhesive. The thickness of the adhesive layer may be, for example, 2 µm or more and 100 µm or less. The resin contained in the release film may be at least any one of the above-mentioned resins listed as the resin contained in each of the first optical film 3 and the second optical film 4 . The composition of the release film may be the same as the composition of the first optical film 3 . The composition of the release film may be different from the composition of the first optical film 3 . The composition of the release film may be the same as the composition of the second optical film 4 . The composition of the release film may be different from the composition of the second optical film 4 . The thickness of the release film may be, for example, 10 µm or more and 100 µm or less. A release film may peel from a polarizing plate and may be removed in the manufacturing process of an image display apparatus. A release film may be arrange|positioned on both surfaces of a polarizing plate through an adhesion layer.

A polarizing plate, as an optical film or layer, a reflective polarizing film, a film having an anti-glare function, a film having a surface anti-reflection function, a reflective film, a transflective film, a viewing angle compensation film, a window film, an antistatic layer, a hard coat layer, You may further provide at least 1 sort(s) selected from the group which consists of an optical compensation layer, a touch sensor layer, and an antifouling|stain-resistant layer.

<Image display device>

A polarizing plate can be used for an image display apparatus. As an image display apparatus, a liquid crystal display device, organic electroluminescent display, etc. are mentioned, for example. A polarizing plate may be used for the polarizing plate arrange|positioned at the visual recognition side of an image display apparatus, may be used for the polarizing plate arrange|positioned at the backlight side of an image display apparatus, and may be used for both the polarizing plate of the visual recognition side and a backlight side. Since a color omission location is hard to conspicuously a polarizing plate, even if it is a case where it is used for the visual recognition side of an image display apparatus, designability is hard to be impaired. Therefore, the image display apparatus is suitable as an image display apparatus having a camera hole, for example, an image display apparatus used in mobile devices such as smartphones and mobile phones, personal computers, and the like.

Example

Hereinafter, the present invention will be described in more detail by way of Examples. In the examples, "%" and "parts" are mass % and parts by mass, unless otherwise specified.

[Heat shock test]

The polarizing plate obtained in the Example and the comparative example was bonded to Corning glass using the adhesive layer. Put this glass-bonded sample in a cold-heat shock tester, and repeat the operation 100 cycles of "holding in a -40 ℃ bath for 30 minutes, then immediately transferring it to an 85 ℃ bath and holding for 30 minutes" as one cycle A heat shock test was performed. The presence or absence of cracks was confirmed using an optical microscope.

[Measurement of boric acid concentration]

The distribution of the concentration of borate ions (BO ₃ ^3- ) was obtained by time-of-flight secondary ion mass spectrometry (TOF-SIMS). As shown in FIG. 11, the protective film bonded to the optical film 5 (thickness 52 µm) side of the polarizing plate 110 was peeled off, and the optical film 9 (thickness 21 µm) was bonded on the pressure-sensitive adhesive layer on the side. The separator film was peeled off, and one end region including the corner of the concave portion was cut out to a length of 1 mm (1000 µm) toward the inside of the polarizing plate with a width of 100 µm to obtain a measurement sample (200). The measurement sample 200 includes an optical film 201 (thickness 52 μm), an adhesive layer 202 (thickness 1 μm), a polarizer 203 (thickness 8 μm), an adhesive layer 204 (thickness 1 μm), and an optical film (205) (thickness of 21 micrometers), it had the adhesive layer 206 (thickness of 20 micrometers) in this order. The ion beam is irradiated while scanning the measurement region 207 in the longitudinal direction (1000 μm) side of the measurement sample 200 to obtain a two-dimensional distribution of the signal intensity of borate ions in this side surface, A portion corresponding to the side surface of the polarizer was cut out from the dimensional distribution, the integrated value of the signal intensity was plotted with respect to the longitudinal direction of the measurement sample 200, and a profile of the boric acid concentration with respect to the longitudinal direction was obtained. The conditions of the time-of-flight secondary ion mass spectrometry (TOF-SIMS) are shown below.

In addition, although the measurement of boric acid concentration was performed in the state of a polarizing plate, it can be considered that the obtained boric acid concentration is the boric acid concentration of a polarizer.

Device name: Product name: PHI TRIFT V nano TOF (Ulbak Pi Co., Ltd.)

Primary ion irradiated: Au ₃ ⁺

Primary ion acceleration voltage: 30 kV

Spatial resolution of the ion beam: 1 μm × 1 μm

Area of measurement area: 200 μm×200 μm

From the obtained boric acid concentration profile, the average value of the boric acid ion strength in the range of 30 µm or more and 60 µm or less from the end is obtained, and from the end to the position where the boric acid ion strength is the average value is defined as the low boric acid concentration site, The length (length of the low boric acid concentration site|part) of the area|region in which the boric-acid low concentration site|part from the edge part of a polarizing plate is formed was measured.

[Iodine missing]

The base-treated portion of the polarizing plate was observed with transmitted light under an optical microscope, the optical microscope image was taken in a personal computer, and as follows, the length of the region where the low iodine concentration site is formed from the polarizing plate end (the length of the low iodine concentration site) length) was measured.

In the optical microscope image taken on the personal computer, the region with low iodine concentration appears bright and the inner region appears dark with the naked eye. Image processing is performed on the optical microscope image, so that the brightness of the low iodine concentration part becomes 180-220 and the brightness of the inner region becomes 100-140, so that it is converted into a black-and-white image of 256 gradations (brightness 255 is white and 0 is black), , the region (white) having a brightness of 180 or more was used as a low iodine concentration region, and it was confirmed whether a low iodine concentration region existed.

[A polarizer with a thickness of 8 μm]

A polyvinyl alcohol film with a thickness of 20 µm (average degree of polymerization of about 2,400, degree of saponification of 99.9 mol% or more) was uniaxially stretched to about 4.9 times by dry stretching, and immersed in pure water at 60°C for 1 minute while maintaining the tension state. After that, it was immersed in an aqueous solution having a weight ratio of iodine/potassium iodide/water of 0.05/5/100 at 28° C. for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 at 72° C. for 300 seconds. Subsequently, after washing|cleaning for 20 second with 26 degreeC pure water, it dried at 65 degreeC, and obtained the 8-micrometer-thick polarizer in which the iodine adsorption orientation is carried out to the polyvinyl alcohol film.

[Polarizer with a thickness of 12 μm]

A polarizer having a thickness of 12 µm was obtained in the same manner as a polarizer having a thickness of 8 µm, except that a polyvinyl alcohol film having a thickness of 30 µm was used and uniaxially stretched to about 5.0 times by dry stretching to obtain a polarizer having a thickness of 12 µm.

[A polarizer with a thickness of 28 μm]

A polarizer having a thickness of 28 µm was obtained in the same manner as a polarizer having a thickness of 8 µm, except that a polyvinyl alcohol film having a thickness of 75 µm was used and uniaxially stretched to about 4 times by dry stretching to obtain a polarizer having a thickness of 28 µm.

[optical film]

COP: A 23-micrometer-thick cycloolefin resin film (made by Nippon Zeon Corporation).

TAC: Triacetyl cellulose film with a thickness of 20 µm (manufactured by Konica Minolta Co., Ltd.).

[Water-Based Adhesive]

With respect to 100 parts of water, 3 parts of carboxyl group-modified polyvinyl alcohol (KL-318 manufactured by Kuraray Co., Ltd.) is dissolved, and in the aqueous solution, a polyamide epoxy-based additive (Sumika Chemtex Co., Ltd.), which is a water-soluble epoxy compound, is dissolved. Sumirez Resin (registered trademark) 650 (30), an aqueous solution having a solid content concentration of 30%] was added to 1.5 parts to obtain a water-based adhesive.

[Example 1]

An optical film (COP film) subjected to corona discharge treatment was bonded to both surfaces of an 8 µm polarizer through a water-based adhesive. An adhesive was apply|coated to the surface on the opposite side to the polarizer of one optical film, the adhesive layer was formed, and the separate film was bonded together on it. This separate film was peelable from the adhesive layer. The protection film was bonded together on the opposite side to the polarizer of the optical film other than the optical film in which the adhesive layer was formed. This protection film was peelable from an optical film. The polarizing plate obtained in this way was chip-cut to 5.5 cm in width and height, and the mold release process which forms the 6mm diameter through-hole using a punching blade was performed.

The humidification process which hold|maintained the obtained polarizing plate continuously for 2 hours in the gaseous phase of the temperature of 85 degreeC and 85% of relative humidity was performed. In this way, the polarizing plate of Example 1 was obtained. A result is shown in Table 1. In addition, in this polarizing plate, light leakage accompanying iodine leakage did not generate|occur|produce, and the length from the edge part of the low iodine concentration site|part was 0 micrometers.

[Example 2]

Except having changed the conditions of a humidification process into the conditions shown in Table 1, it carried out similarly to Example 1, and produced the polarizing plate of Example 2. A result is shown in Table 1. Moreover, the measurement result of the boric acid concentration with respect to the distance from the edge part of a polarizing plate is shown in FIG. Moreover, the observation result of iodine loss is shown in FIG.

[Example 3]

Except having changed the conditions of a humidification process into the conditions shown in Table 1, it carried out similarly to Example 1, and produced the polarizing plate of Example 3. A result is shown in Table 1.

[Comparative Example 1]

Except having changed the conditions of a humidification process into the conditions shown in Table 1, it carried out similarly to Example 1, and produced the polarizing plate of Comparative Example 1. A result is shown in Table 1.

[Comparative Example 2]

Except having changed the conditions of a humidification process into the conditions shown in Table 1, it carried out similarly to Example 1, and produced the polarizing plate of the comparative example 2. A result is shown in Table 1.

[Comparative Example 3]

A polarizing plate of Comparative Example 3 was produced in the same manner as in Example 1 except that it was immersed in hot water at a temperature of 74°C for 16 minutes instead of performing the humidification treatment. A result is shown in Table 1. The observation result of iodine depletion is shown in FIG. In this polarizing plate, the low iodine concentration site|part due to iodine loss|extraction generate|occur|produced, and the length was about 250 micrometers.

[Example 4]

An optical film COP subjected to corona discharge treatment is bonded to one side of a 12 μm polarizer through a water-based adhesive, and an optical film TAC subjected to corona discharge treatment is bonded to the other side through a water-based adhesive to produce a polarizing plate did The obtained polarizing plate was chip-cut to 5.5 cm in width and height, and the mold release process which forms a 6-mm diameter through hole was performed.

The humidification process which hold|maintained the obtained polarizing plate in the gaseous phase of 85 degreeC of temperature and 85% of relative humidity for 2 hours was performed. In this way, the polarizing plate of Example 4 was obtained. A result is shown in Table 2.

[Example 5]

Except having changed the conditions of a humidification process into the conditions shown in Table 2, it carried out similarly to Example 4, and produced the polarizing plate of Example 5. A result is shown in Table 2.

[Comparative Example 4]

Except having changed the conditions of a humidification process into the conditions shown in Table 2, it carried out similarly to Example 4, and produced the polarizing plate of the comparative example 4. A result is shown in Table 2.

[Comparative Example 5]

Except having changed the conditions of a humidification process into the conditions shown in Table 2, it carried out similarly to Example 4, and produced the polarizing plate of the comparative example 5. A result is shown in Table 2.

[Comparative Example 6]

Except having changed the conditions of a humidification process into the conditions shown in Table 2, it carried out similarly to Example 4, and produced the polarizing plate of the comparative example 6. A result is shown in Table 2.

[Comparative Example 7]

The optical film COP subjected to corona discharge treatment is bonded to one side of a 28 μm polarizer through a water-based adhesive, and the optical film TAC subjected to corona discharge treatment is bonded to the other side through a water-based adhesive to produce a polarizing plate. did The obtained polarizing plate was chip-cut to 5.5 cm in width and height, and the mold release process which forms a 6-mm diameter through hole was performed.

The humidification process which hold|maintained the obtained polarizing plate in the gaseous phase of 85 degreeC of temperature and 85% of relative humidity for 2 hours was performed. In this way, the polarizing plate of Comparative Example 7 was obtained. The results are shown in Table 3 together with the results of Examples 1 and 2.

[Comparative Example 8]

Except having changed the conditions of a humidification process into the conditions shown in Table 3, it carried out similarly to the comparative example 7, and produced the polarizing plate of the comparative example 8. The results are shown in Table 3 together with the results of Examples 1 and 2.

1: Polarizer 2, 7: Polarizer
3, 5: First optical film 4, 9: Second optical film
10: 1st laminated body 13: recessed part
14: through hole 15: third optical film
20: image display device 21: polarizing plate
22: camera hall 23: liquid crystal panel
24 cover glass 25 pressure-sensitive adhesive layer
26: polarizer 27: camera
28: light-shielding tape 30: boric acid low concentration area
31: middle region 32: inner region
50: end mill 50e: blade (edge)
100: second laminate 110: polarizing plate
200: measurement samples 201, 205: optical film
202, 204: adhesive layer 203: polarizer
206: pressure-sensitive adhesive layer 207: measurement area
α: twist angle β: cutting angle

Claims (10)

As a manufacturing method of a polarizing plate,
A first lamination step of bonding an optical film to at least one side of a polarizer having a thickness of 15 μm or less to produce a first laminate;
The humidification treatment process of holding a 1st laminated body in the gaseous phase of 75% RH or more of relative humidity in the temperature of 35 degreeC or more.
A method of manufacturing a polarizing plate comprising a. The method for manufacturing a polarizing plate according to claim 1, further comprising a molding process of molding the first laminate before the humidifying process. The manufacturing method of the polarizing plate of Claim 2 which forms a mold part in the said 1st laminated body in the said shaping|molding process. The manufacturing method of the polarizing plate of Claim 2 or 3 further comprising the cutting process of cutting the said 1st laminated body before the said humidification process. The said 1st laminated body is cut in the said cutting process so that the position of the edge part of an optical film and the position of the edge part of a polarizer may become the same in the plan view of the said 1st laminated body. A method for manufacturing a polarizing plate to be processed. A polarizer comprising a resin film containing boric acid and iodine and having a thickness of 15 µm or less,
In the region including the end portion of the polarizer, it has a region containing boric acid at a concentration lower than the concentration of boric acid in regions other than this region;
A polarizer in which iodine loss has not occurred in the region including the edge portion of the polarizer. The polarizing plate which has the polarizer of Claim 6, and the optical film bonded by at least one of the said polarizer. The polarizing plate according to claim 7, wherein the position of the end of the polarizer and the position of the end of the optical film are the same at the end of the polarizing plate in a planar view. The image display apparatus provided with the polarizing plate of Claim 8. The image display device according to claim 9, having a camera hole.

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