KR20220044425A - Polarizing plate and organic el display device - Google Patents

Abstract

The present invention provides a novel polarizing plate capable of increasing the lifespan of a display device even when the polarizing plate is used together with an organic EL display panel. A linear polarizing plate includes a polarizer. The absorbance A_450 at a wavelength of 450 nm satisfies the following relation (1), and the absorbance A_750 at a wavelength of 750 nm satisfies the following relational expression (2), wherein 1.6 <= A_450 <= 2.7 (1) and 0.7 <= A_750 <= 2.3 (2).

Description

Polarizing plate and organic EL display device {POLARIZING PLATE AND ORGANIC EL DISPLAY DEVICE}

The present invention relates to a polarizing plate and an organic EL display including the polarizing plate.

BACKGROUND ART An organic electroluminescence (organic EL) display device is a self-luminous thin display device, and has advantages in display performance such as high visibility and little viewing angle dependence as compared with a liquid crystal display device. Moreover, in addition to the advantage of being able to reduce the weight and thickness of an image display apparatus (display), since a flexible image display apparatus can be implement|achieved, it has the possibility that an image display apparatus different from the past can be implement|achieved.

However, since an organic EL display device uses a metal material having high reflectance as an electrode (metal electrode) in some cases, external light is reflected at the interface of the metal electrode, and there is a problem of reflection due to a decrease in contrast or internal reflection. may occur (external light reflection).

In order to suppress the bad influence by external light reflection, the proposal of using a linearly polarizing plate and the circularly-polarizing plate containing (lambda) / 4 phase difference layer as an antireflection plate is made|formed (for example, refer patent document 1, 2).

Patent Document 1: Japanese Patent Laid-Open No. Hei 7-142170 Patent Document 2: Japanese Patent Laid-Open No. Hei 9-127885

In an organic EL display panel, the lifetime of a blue light emitting element may be short compared with the lifetime of the light emitting element of another color. An object of the present invention is to provide a novel polarizing plate capable of increasing the lifespan of a display device even when used together with an organic EL display panel, and an organic EL display device including the polarizing plate.

The present invention provides the following polarizing plate and organic EL display device.

[1] including a polarizer,

Absorbance A ₄₅₀ at a wavelength of 450 nm satisfies the following relational expression (1),

A polarizing plate whose absorbance A ₇₅₀ at a wavelength of 750 nm satisfies the following relational expression (2).

1.6≤A ₄₅₀ ≤2.7 (1)

0.7≤A ₇₅₀ ≤2.3 (2)

[2] The polarizing plate according to [1], wherein the absorbance A ₇₀₀ at a wavelength of 700 nm satisfies the following relational expression (3).

1.7≤A ₇₀₀ ≤4.5 (3)

[3] The polarizing plate according to [1] or [2], wherein the b-value of the orthogonal hue is -1.5 or less.

[4] The polarizing plate according to [3], wherein the b-value of the orthogonal hue is -20 or more.

[5] The polarizing plate according to any one of [1] to [4], wherein the polarizer has a thickness of 7 µm or more and 30 µm or less.

[6] The polarizing plate according to any one of [1] to [5], further comprising a protective film bonded to at least one surface of the polarizer.

[7] The polarizing plate according to any one of [1] to [6], further comprising a λ/4 retardation layer.

[8] The polarizing plate according to [7], wherein the polarizing plate is used by being disposed on the viewing-side surface of the organic EL display panel.

[9] An organic EL display device comprising an organic EL display panel and the polarizing plate according to [8].

ADVANTAGE OF THE INVENTION According to the polarizing plate of this invention, even when used together with an organic electroluminescent display panel, lifetime improvement of a display apparatus can be aimed at.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows an example of the layer structure of the polarizing plate which concerns on this invention.
It is a schematic sectional drawing which shows another example of the layer structure of the polarizing plate which concerns on this invention.
3 is a cross-sectional view showing an example of a method for manufacturing a polarizer according to the present invention.
Fig. 4 is a schematic cross-sectional view showing an example of a layer configuration of a circularly polarizing plate as one embodiment of the polarizing plate according to the present invention.
Fig. 5 is a schematic cross-sectional view showing another example of the layer configuration of a circularly polarizing plate that is one embodiment of the polarizing plate according to the present invention.

<Polarizer and Polarizer>

(1) Basic configuration of polarizing plate

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows an example of the layer structure of the polarizing plate which concerns on this invention. Like the polarizing plate 1 shown in FIG. 1, the polarizing plate of this invention is the 1st protective film 3 laminated|stacked through the polarizer 5 and the 1st adhesive bond layer 6 on the one surface, and another It may be provided with a second protective film (4) laminated on the other side with a second adhesive layer (7) interposed therebetween. The polarizing plate 1 may further have another optical function layer, an adhesive layer, etc. laminated|stacked on the 1st protective film 3 and/or the 2nd protective film 4 .

Moreover, like the polarizing plate 2 shown in FIG. 2, the polarizing plate of this invention is equipped with the polarizer 5 and the 1st protective film 3 laminated|stacked through the 1st adhesive bond layer 6 on the one surface. A polarizing plate having a single-sided protective film may be used. The polarizing plate 2 may further have another optical function layer, an adhesive layer, etc. laminated|stacked on the 1st protective film 3 and/or the polarizer 5.

(2) Absorbance characteristics of polarizing plate

The polarizing plate of the present invention contains a polarizer, and the absorbance A ₄₅₀ at a wavelength of 450 nm satisfies the following relational expression (1), and the absorbance A ₇₅₀ at a wavelength of 750 nm satisfies the following relation (2).

1.6≤A ₄₅₀ ≤2.7 (1)

0.7≤A ₇₅₀ ≤2.3 (2)

Here, "absorbance A ₇₅₀ " and "absorbance A ₄₅₀ " of the polarizing plate indicate the absorbance in the skirt of the absorption band on the long wavelength side (red region) and the absorbance in the skirt of the absorption band on the short wavelength side (blue region), respectively. . In general, since the absorption bands on the long and short wavelength sides of a polarizing plate are very large, the intensity of the absorption bands on the long and short wavelength sides is often saturated and cannot be grasped by the ultraviolet and visible spectrophotometer. It was sufficiently correlated with "absorbance A ₇₅₀ " and "absorbance A ₄₅₀ ", and it was found that the intensity of the absorption bands on the long-wavelength side and short-wavelength side can be evaluated by "absorbance _A750 " and "absorbance _A450 ", respectively.

In the polarizing plate of the present invention satisfying the above relational expressions (1) and (2), the absorbance A ₄₅₀ at a wavelength of 450 nm correlated with the absorption band in the blue region is the absorbance at a wavelength of 750 nm that is correlated with the absorption band on the long wavelength side Since it is higher than or equal to that of A ₇₅₀ , even if the amount of light of the blue light emitting element in the organic EL display panel is reduced, blue light can be sufficiently transmitted, which may cause shortening of the life of the organic EL display element. It suppresses shortening of a blue light emitting element which can be made possible, and further contributes to life extension of an organic electroluminescent display apparatus.

In addition, the polarizing plate of the present invention exhibiting the above light absorption characteristics, the reason is not completely clear, by setting the transmittance in the blue region to an appropriate range, and improving the stability of the iodine complex in the polarizer, the degree of polarization even when subjected to a heat resistance test change can be suppressed. The fact that the change in polarization degree can be suppressed even when subjected to a heat resistance test means that even when subjected to a heat resistance test, absorbance A _{450 correlated} with the absorption band in the blue region is higher ( or equivalent) state can be maintained, and even if the organic EL display device is used in a high-temperature environment, shortening of the blue light-emitting element is suppressed and the lifespan of the organic EL display device is contributed.

As for the polarizing plate of this invention, it is preferable that the absorbance A700 in wavelength _700nm satisfy|fills the following relational expression (3).

1.7≤A ₇₀₀ ≤4.5 (3)

The b-value of the orthogonal hue of the polarizing plate is preferably -1.5 or less, more preferably -3.0 or less from the viewpoint of efficiently transmitting light having a short wavelength. Further, the b-value of the orthogonal hue of the polarizing plate is preferably -20 or more, more preferably -19 or more, from the viewpoint that the hue is too blue and visibility deteriorates. The b-value of the orthogonal color is measured according to the description of the section of Examples to be described later.

The absorbance A ₄₅₀ , the absorbance A ₇₅₀ , and the absorbance A ₇₀₀ of the polarizing plate can be measured using a light absorption spectrometer such as an ultraviolet and visible spectrophotometer. Natural light is used for the incident light. When the incident light intensity is T ₀ and the transmitted light intensity is T, the absorbance (absorbance A ₄₅₀ , absorbance A ₇₅₀ and absorbance A ₇₀₀ ) is obtained by the following formula:

It is obtained according to absorbance=-log(T/T ₀ ).

In addition, if the incident light incident on the sample (polarizing plate) has polarization properties, the obtained absorbance value may fluctuate depending on the orientation when the sample is set in a light absorption spectrometer. For example, depending on the absorption spectrometer, some polarization occurs in the incident light due to the influence of a mirror or optical element between the light source and the sample, or a polarization separating element such as a prism is included in some cases. Caution is needed. In the case of using such a light absorption spectrometer, the polarizing plate is measured at a certain angle (meaning a certain orientation around the optical axis), then measured again at the orientation rotated by 90 degrees, and the absorbance is calculated from the average transmitted light intensity. The influence of the polarization property of the incident light can be eliminated.

(3) Polarization characteristics of polarizing plate

The polarization performance of the polarizing plate can be mainly expressed by numerical values called single transmittance and polarization degree, and each of the following formulas:

Single transmittance (λ)=0.5×(Tp(λ)+Tc(λ))

Polarization degree (λ)=100×(Tp(λ)-Tc(λ))/(Tp(λ)+Tc(λ))

is defined as

Here, Tp(λ) is the transmittance (%) of the polarizing plate measured by the relationship between the incident linearly polarized light having a wavelength of λ nm and parallel Nicols, and Tc(λ) is the difference between the incident linearly polarized light having a wavelength of λ nm and crossed Nicols. It is the transmittance|permeability (%) of the polarizing plate measured by the relationship, and all are measured values obtained by the polarization|polarized-light ultraviolet-visible absorption spectrum measurement with a spectrophotometer. In addition, to the single transmittance (λ) and polarization degree (λ) obtained for each wavelength, to which a sensitivity correction called visibility correction is added is called visibility correction single transmittance (Ty) and visibility correction polarization degree (Py), respectively. The values of these Ty and Py can be easily measured with, for example, an absorption photometer (model number: V7100) manufactured by Nippon Bunko Co., Ltd. or the like.

In order to ensure good clarity of an image when the polarizing plate is applied to a display device, the polarizing plate or polarizer according to the present invention has a visibility correction single transmittance (Ty) of 40.0% or more, preferably 42.0% or more, and 44.0% It is more preferable that it is more than it, and it is still more preferable that it is 45.0 % or more. It is preferable that visibility correction|amendment polarization degree (Py) is 99 % or more.

(4) Polarizer

The polarizer 5 may be a uniaxially stretched polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and oriented. In this invention, the thickness of the polarizer 5 is 7 micrometers or more and 30 micrometers or less, for example, More preferably, they are 10 micrometers or more and 30 micrometers or less, More preferably, they are 12 micrometers or more and 25 micrometers or less. By using the polarizer 5 of such a thickness, it is easy to obtain the polarizing plate which satisfy|fills said relational formula (1) and (2).

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). As a typical polarizer, a dichroic dye is adsorbed and oriented to a uniaxially stretched polyvinyl alcohol-based resin film. Such a polarizer is, for example, a step of uniaxially stretching a polyvinyl alcohol-based resin film; The step of adsorbing a dichroic dye by dyeing a polyvinyl alcohol-type resin film with a dichroic dye (dyeing process); a step of treating the polyvinyl alcohol-based resin film to which the dichroic dye has been adsorbed with a crosslinking solution such as an aqueous boric acid solution (crosslinking treatment); and a process (washing treatment) of washing with water after treatment with a crosslinking solution.

As polyvinyl alcohol-type resin, what saponified polyvinyl acetate-type resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and other copolymerizable monomers. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

In this specification, "(meth)acryl" means at least one chosen from acryl and methacryl. It is the same also in "(meth)acryloyl", "(meth)acrylate", etc.

The saponification degree of polyvinyl alcohol-type resin is 85-100 mol% normally, and 98 mol% or more is preferable. The polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The average degree of polymerization of polyvinyl alcohol-type resin is 1000-10000 normally, and 1500-5000 are preferable. The average degree of polymerization of polyvinyl alcohol-type resin can be calculated|required based on JISK6726.

The examples of the commercial item of the polyvinyl alcohol-type resin used suitably in this invention are all brand names, "PVA124" (saponification degree: 98.0-99.0 mol%) by Kuraray Co., Ltd., "PVA117" (saponification degree) : 98.0-99.0 mol%), "PVA624" (saponification degree: 95.0-96.0 mol%), "PVA617" (saponification degree: 94.5-95.5 mol%); "AH-26" (saponification degree: 97.0 to 98.8 mol%), "AH-22" (saponification degree: 97.5 to 98.5 mol%), "NH-18" (saponification degree: 97.5 to 98.5 mol%) manufactured by Nippon Kosei Chemicals Co., Ltd. : 98.0-99.0 mol%), "N-300" (saponification degree: 98.0-99.0 mol%); "JC-33" (saponification degree: 99.0 mol% or more), "JM-33" (saponification degree: 93.5-95.5 mol%), "JM-26" (saponification degree: 95.5 mol%) manufactured by Nippon Sakubi Poval Co., Ltd. -97.5 mol%), "JP-45" (saponification degree: 86.5-89.5 mol%), "JF-17" (saponification degree: 98.0-99.0 mol%), "JF-17 L" (saponification degree: 98.0- 99.0 mol%) and "JF-20" (saponification degree: 98.0-99.0 mol%).

What produced such a polyvinyl alcohol-type resin into a film is used as a raw film for polarizer manufacture (polyvinyl alcohol-type resin film). The method of manufacturing a film|membrane of polyvinyl alcohol-type resin will not be limited if it is a method which can obtain the polarizer which comprises the polarizing plate of this invention which satisfy|fills said relational formula (1) and (2). Moreover, it is preferable that a polarizer satisfy|fills the said relational formulas (1) and (2), and it is more preferable that it further satisfy|fills Formula (3).

Uniaxial stretching of a polyvinyl alcohol-type resin film may be performed before the dyeing process by a dichroic dye, may be performed simultaneously with the said dyeing process, and may be performed after a dyeing process. When uniaxial stretching is performed after the dyeing treatment, such uniaxial stretching may be performed before the crosslinking treatment or during the crosslinking treatment. Moreover, you may divide and perform uniaxial stretching into a plurality of times in these plurality of processing steps.

In uniaxial stretching, when a long polyvinyl alcohol-based resin film is used, for example, the polyvinyl alcohol-based resin film is placed over a roll, and the circumferential speed of the roll is varied so that it may be uniaxially stretched between the rolls. , may be uniaxially stretched using a hot roll. The uniaxial stretching may be dry stretching in the air, or wet stretching in which the polyvinyl alcohol-based resin film is swelled using a solvent or water. A draw ratio is 3 to 8 times normally. When extending|stretching a polyvinyl alcohol-type resin film by uniaxial stretching of multiple times, it is made so that the draw ratio compared with the original length may be set to 3 to 8 times normally. In addition, this draw ratio can be selected so that the finally obtained polarizer may become a desired thickness.

As a method of dyeing a polyvinyl alcohol-type resin film with a dichroic dye (dyeing process), the method of immersing this polyvinyl alcohol-type resin film in the aqueous solution containing a dichroic dye is typically employ|adopted. As the dichroic dye, iodine and dichroic organic dye are used. Moreover, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

As a crosslinking process after the dyeing process with a dichroic dye, the method of immersing the dyed polyvinyl alcohol-type resin film in boric-acid containing aqueous solution, etc. are usually employ|adopted. When using an iodine as a dichroic dye, it is preferable that this boric-acid containing aqueous solution contains potassium iodide.

The dichroic dye contained in the polarizer (adsorption orientation) may be iodine or a dichroic organic dye. Specific examples of the dichroic organic dye include Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet. B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Direct Sky blue, direct first orange S, and first black. A dichroic dye may be used individually by 1 type, and may use 2 or more types together.

A polarizer may be manufactured from the polyvinyl alcohol-type resin film, and may be manufactured from the laminated body (polyvinyl alcohol-type resin laminated body) which formed the polyvinyl alcohol-type resin layer on the base material. The polyvinyl alcohol-based resin laminate can be obtained by, for example, a method of applying a coating liquid containing a polyvinyl alcohol-based resin to a substrate, a method of laminating a polyvinyl alcohol-based resin on a substrate, and the like. The process of uniaxially stretching a polyvinyl alcohol-type resin laminated body for a polyvinyl alcohol-type resin laminated body; a step of adsorbing a dichroic dye by dyeing the uniaxially stretched polyvinyl alcohol-based resin laminate with a dichroic dye; a step of treating the polyvinyl alcohol-based resin laminate to which the dichroic dye has been adsorbed with a crosslinking solution such as an aqueous boric acid solution; and the process of washing with water after the process by a crosslinking liquid, etc. are provided, and a polarizer is manufactured.

A polarizer may be used as a polarizing plate by the structure which bonded together the protective film on the single side|surface or both surfaces of a polarizer, as shown in FIG.1 and FIG.2, and may use it independently as a polarizing plate.

(5) first and second protective films

Each of the first protective film 3 and the second protective film 4 is formed of a thermoplastic resin such as a polyolefin-based resin such as a chain polyolefin-based resin (polypropylene-based resin, etc.) or a cyclic polyolefin-based resin (norbornene-based resin, etc.). profit; Cellulose ester-based resins such as cellulose triacetate and cellulose diacetate; polyester-based resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate-based resin; (meth)acrylic resin; Or it may be a transparent resin film including a mixture or copolymer thereof. The 1st protective film 3 and the 2nd protective film 4 may be mutually the same kind of protective film, and a different kind of protective film may be sufficient as them.

Cyclic polyolefin-based resin is a generic name for resins polymerized using cyclic olefin as a polymerization unit, and for example, Japanese Patent Application Laid-Open No. Hei 1-240517, Japanese Unexamined Patent Publication No. Hei 3-14882, and Japanese Patent Application Laid-Open No. Hei3-122137 and resins described in publications and the like. Specific examples of the cyclic polyolefin-based resin include a ring-opened (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a copolymer of a cyclic olefin and a chain olefin such as ethylene and propylene (typically a random copolymer) and unsaturated Graft polymers modified with carboxylic acids or derivatives thereof, hydrides thereof, and the like. Among them, norbornene-based resins using norbornene-based monomers such as norbornene and polycyclic norbornene-based monomers are preferably used as cyclic olefins.

As for the cyclic polyolefin resin, various products are marketed. Examples of commercially available cyclic polyolefin resins are all brand names, and "Topas" (manufactured by Topas Advanced Polymers GmbH, available from Poly Replastics Co., Ltd.), "Aton" (manufactured by JSR Co., Ltd.), " ZEONOR" (manufactured by Nippon Zeon Co., Ltd.), "ZEONEX" (manufactured by Nippon Zeon Co., Ltd.), and "Apel" (manufactured by Mitsui Chemicals Co., Ltd.) are included.

In addition, all of these are brand names, and "Sucina" (manufactured by Sekisui Chemical Co., Ltd.), "SCA40" (manufactured by Sekisui Chemical Co., Ltd.), "Zeonor Film" (manufactured by Nippon Zeon Co., Ltd.) A commercially available cyclic polyolefin-based resin film produced as a film may be used as a protective film.

Cellulose ester-type resin is ester of a cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Moreover, these copolymers and those in which a part of hydroxyl groups were modified with other substituents can also be used. Among these, cellulose triacetate (triacetyl cellulose: TAC) is especially preferable. Cellulose triacetate has many products on the market and is advantageous also in terms of availability and cost. Examples of commercial products of cellulose triacetate are all brand names, "Fujitack TD80" (manufactured by Fujifilm Co., Ltd.), "Fujitack TD80UF" (manufactured by Fujifilm Co., Ltd.), "Fujitack TD80UZ" (Fujifilm ( Manufactured by Co., Ltd.), "Fujitac TD40UZ" (manufactured by Fujifilm Co., Ltd.), "KC8UX2M" (manufactured by Konica Minolta Opto Co., Ltd.), and "KC4UY" (manufactured by Konica Minolta Opto Co., Ltd.) are included.

The 1st protective film 3 and/or the 2nd protective film 4 may be a protective film which has optical functions like retardation film and a brightness improvement film together. For example, by stretching (uniaxial stretching or biaxial stretching, etc.) a transparent resin film containing the above material, or forming a liquid crystal layer or the like on the film, a retardation film to which an arbitrary retardation value is imparted can be obtained.

On the surface on the opposite side to the polarizer 5 of the 1st protective film 3 and/or the 2nd protective film 4, surface treatment layers (coating layer) such as a hard-coat layer, a glare-proof layer, an antireflection layer, an antistatic layer, and an antifouling layer. ) can also be formed. The method of forming a surface treatment layer on the protective film surface is not specifically limited, A well-known method can be used.

As for the thickness of the 1st and 2nd protective films 3 and 4, 5-90 micrometers or less are preferable, More preferably, it is 5-60 micrometers, More preferably, it is 5-50 micrometers.

(6) first and second adhesive layers

As the adhesive for forming the first and second adhesive layers 6 and 7, a water-based adhesive or a photocurable adhesive can be used. The adhesive agent which forms the 1st adhesive bond layer 6 and the adhesive agent which forms the 2nd adhesive bond layer 7 may be of the same type or different types may be sufficient as them.

Examples of the water-based adhesive include an adhesive containing a polyvinyl alcohol-based resin aqueous solution, a water-based two-part type urethane-based emulsion adhesive, and the like. Especially, the aqueous adhesive agent containing polyvinyl alcohol-type resin aqueous solution is used suitably.

As the polyvinyl alcohol-based resin, in addition to a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, a polyvinyl alcohol-based copolymer obtained by saponifying a copolymer of vinyl acetate and another monomer copolymerizable therewith. , or a modified polyvinyl alcohol-based polymer in which these hydroxyl groups are partially modified can be used. The water-based adhesive may contain additives such as polyhydric aldehydes, water-soluble epoxy compounds, melamine-based compounds, zirconia compounds, and zinc compounds. When a water-based adhesive is used, the thickness of the adhesive bond layer obtained after that is 1 micrometer or less normally.

The bonding method of the polarizer 5 and the protective film using the water-based adhesive is not particularly limited, and the water-based adhesive is uniformly applied or flowed on one bonding surface, and the other side is overlapped on the application surface and bonded by a roll, etc., and dried. method and the like. Usually, a water-based adhesive agent is apply|coated under the temperature of 15-40 degreeC after the preparation, and bonding temperature is the range of 15-30 degreeC normally.

When using a water-based adhesive agent, it is preferable to perform the drying process of drying in order to remove the water contained in a water-system adhesive agent after bonding. Drying can be performed by introduce|transducing the film after bonding into a drying furnace, for example. Drying temperature (temperature of a drying furnace) becomes like this. Preferably it is 30-90 degreeC. There exists a tendency for a protective film to become easy to peel from the polarizer 5 as it is less than 30 degreeC. Moreover, when a drying temperature exceeds 90 degreeC, there exists a possibility that the polarization|polarized-light performance of the polarizer 5 may deteriorate with a heat|fever. Drying time can be made into 10-1000 second, for example.

After the drying step, a curing step of curing for 12 to 600 hours at room temperature or a temperature slightly higher than that, for example, at a temperature of 20 to 45°C may be provided. The curing temperature is generally set lower than the drying temperature.

The photocurable adhesive refers to an adhesive that is cured by irradiating active energy rays such as ultraviolet rays, and includes, for example, a polymerizable compound and a photopolymerization initiator, a photoreactive resin, a binder resin, and a photoreactive crosslinking agent. to do, etc. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers and photocurable urethane monomers, and oligomers derived from photopolymerizable monomers. As a photoinitiator, the thing containing the substance which generate|occur|produces active species like a radical, an anion, and a cation by irradiation of active energy rays, such as an ultraviolet-ray, is mentioned. As a photocurable adhesive agent containing a polymerizable compound and a photoinitiator, what contains a photocurable epoxy-type monomer and a photocationic polymerization initiator can be used preferably.

The bonding method of the polarizer 5 and the protective film using the photocurable adhesive is not particularly limited, and for example, a casting method, a Meyer bar coating method, a gravure coating method, a comma coater method, a doctor plate method, and a die According to a coating method, a dip coating method, a spraying method, etc., the method of apply|coating a photocurable adhesive agent to one bonding surface, superposing|polymerizing both, sandwiching it with a nip roll etc. and bonding is mentioned. The casting method is a method of flowing and spreading an adhesive on the bonding surface while moving the coated object in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between both. It is preferable that the thickness before drying or hardening of the adhesive bond layer after bonding using a nip roll etc. is 5 micrometers or less and 0.01 micrometer or more.

In the case of using a photocurable adhesive, after performing the above-described bonding, a drying step is performed as necessary (when the photocurable adhesive contains a solvent, etc.), followed by a curing step of curing the photocurable adhesive by irradiating active energy rays do The light source of the active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable, and specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a chemical lamp, a black light lamp, a micro A wave-excited mercury lamp, a metal halide lamp, etc. are used preferably.

The light irradiation intensity to the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive, and is preferably set so that the irradiation intensity in the wavelength region effective for activation of the polymerization initiator is 0.1 to 6000 mW/cm 2 . When the irradiation intensity is 0.1 mW/cm2 or more, the reaction time does not become too long, and when it is 6000 mW/cm2 or less, yellowing of the photocurable adhesive or deterioration of the polarizer due to heat radiated from the light source and heat generated during curing of the photocurable adhesive is less likely to cause

The light irradiation time to the photocurable adhesive is also appropriately determined depending on the composition of the photocurable adhesive, and is preferably set so that the accumulated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 10000 mJ/cm 2 . When the accumulated light amount is 10 mJ/cm 2 or more, a sufficient amount of active species derived from the polymerization initiator can be generated to more reliably advance the curing reaction, and when it is 10000 mJ/cm 2 or less, the irradiation time is not excessively long, and good productivity is maintained. can

Moreover, the thickness of the adhesive bond layer after active energy ray irradiation is 0.01-5 micrometers normally, Preferably it is 0.01-2 micrometers, More preferably, it is 0.01-1 micrometer.

<Method for manufacturing polarizer>

One aspect of the manufacturing method of the polarizer used for the polarizing plate of this invention is demonstrated. In this aspect, as a starting material of polarizer manufacture, thickness becomes like this. Preferably it is 80 micrometers or less, More preferably, it is 60 micrometers or less, Preferably it is 10 micrometers or more, More preferably, it is an unstretched polyvinyl alcohol-type resin film of 15 micrometers or more. (fabric film) is used. The width of the raw film is not particularly limited, and may be, for example, 400 to 6000 mm. A raw film is prepared, for example as a roll (raw roll) of a long unstretched polyvinyl alcohol-type resin film.

The polarizer is continuously conveyed along the film conveying path of the polarizer manufacturing apparatus while unwinding the elongated raw film from the roll roll, immersed in the treatment solution accommodated in the treatment tank (hereinafter also referred to as “treatment bath”) and then pulled out After performing a predetermined processing process, it can manufacture continuously as a long polarizer by performing a drying process. In addition, the treatment process is not limited to a method of immersing the film in a treatment bath as long as it is a method of treating the film by contacting the treatment liquid, and the film is treated by attaching the treatment liquid to the film surface by spraying, dripping, dripping, etc. It might be a good way When the treatment step is performed according to a method of immersing the film in a treatment bath, the treatment bath for performing one treatment step is not limited to one, and even if one treatment step is completed by sequentially immersing the film in two or more treatment baths good.

Examples of the treatment liquid include a swelling liquid, a dyeing liquid, a crosslinking liquid, a complementary color liquid, and a washing liquid. And, as the treatment step, a swelling step of performing a swelling treatment by contacting the raw film with a swelling solution, a dyeing step of performing a dyeing treatment by contacting the dyeing solution with the film after the swelling treatment, and a crosslinking solution in contact with the film after the dyeing treatment Examples include a crosslinking step of performing crosslinking treatment with a crosslinking treatment, a complementary color step of performing a complementary color treatment by contacting a complementary color solution to the film after crosslinking treatment, and a cleaning step of performing a cleaning treatment by contacting the complementary color treatment film with a cleaning solution. In addition, between these series of treatment steps (that is, before and after any one or more treatment steps and/or during any one or more treatment steps), the uniaxial stretching treatment is performed in a wet or dry manner. You may add another treatment process as needed.

Hereinafter, an example of the manufacturing method of the polarizer which concerns on this invention is demonstrated in detail, referring FIG. 3 : is sectional drawing which shows typically an example of the manufacturing method of the polarizer which concerns on this embodiment invention, the manufacturing method of the polarizer used for it, and a manufacturing apparatus. The polarizer manufacturing apparatus shown in FIG. 3 conveys the raw material (unstretched) film 10 containing a polyvinyl alcohol-type resin along the film conveyance path while continuously unwinding from the raw material roll 11, On the film conveyance path A swelling bath (swelling solution accommodated in a swelling tank) 13, a dyeing bath (dyeing solution accommodated in a dyeing tank) 15, a crosslinking bath (crosslinking solution accommodated in a crosslinking tank) 17a, a complementary color bath (complementary color bath) provided in The complementary color liquid) 17b and the washing bath (cleaning liquid accommodated in the washing tank) 19 are sequentially passed through, and finally, the drying furnace 21 is passed through. The obtained polarizer 23 can be conveyed to the next polarizing plate preparation process (process of bonding a protective film on the single side|surface or both surfaces of the polarizer 23) as it is, for example. The arrow in FIG. 3 has shown the conveyance direction of a film.

In the description of FIG. 3 , "treatment tank" is a generic term including a swelling tank, a dyeing tank, a crosslinking tank, a complementary color tank, and a washing tank, and "treatment liquid" is a swelling liquid, a dyeing liquid, a crosslinking liquid, and a complementary color liquid. and washing liquid, and "treatment bath" is a general term including a swelling bath, a dyeing bath, a crosslinking bath, a complementary color bath, and a washing bath.

The film conveyance path of a polarizer manufacturing apparatus presses and pinches|supports the film conveyed other than the said process bath, or guide roll 30-48, 60, 61 which can also change a film conveyance direction, and a conveyed film. It can be constructed by arranging the nip rolls 50 to 55 capable of providing the film with a driving force accompanying the rotation or changing the film conveying direction at an appropriate position. A guide roll and a nip roll can be arrange|positioned in front and back of each process bath, or in a process bath, and can perform introduction/immersion of the film to a process bath, and extraction|take-out from a process bath by this [refer FIG. 3]. For example, a film can be immersed in each treatment bath by providing one or more guide rolls in each treatment bath, and conveying a film along these guide rolls.

As for the polarizing film manufacturing apparatus shown in FIG. 3, nip rolls are arrange|positioned before and behind each process bath (nip rolls 50-54), and by this, in any one or more process baths, between the nip rolls arrange|positioned before and behind it. It has become possible to perform extending|stretching between rolls which perform longitudinal uniaxial stretching with a circumferential speed difference. Hereinafter, each process is demonstrated.

(swelling process)

A swelling process is performed for the objective, such as foreign material removal on the surface of the raw film 10, the plasticizer removal in the raw film 10, provision of dichromaticity, and plasticization of the raw film 10. Treatment conditions are determined within a range that can achieve the above object, and within a range that does not cause problems such as extreme dissolution or devitrification of the raw film 10 .

Referring to FIG. 3 , in the swelling process, the raw film 10 is continuously released from the raw roll 11 , and transported along the film transport path, and the raw film 10 is immersed in the swelling bath 13 for a predetermined time. Then, it can be carried out by withdrawing. In the example of FIG. 3 , from unrolling the raw film 10 to being immersed in the swelling bath 13 , the raw film 10 is formed by the guide rolls 60 , 61 and the nip roll 50 . It is conveyed along the established film conveyance path. In a swelling process, it is conveyed along the film conveyance path built with the guide rolls 30-32 and the nip roll 51.

As the swelling liquid of the swelling bath 13, in addition to pure water, boric acid (Japanese Patent Application Laid-Open No. Hei 10-153709), chloride (Japanese Patent Application Laid-Open No. Hei 06-281816), inorganic acids, inorganic salts, water-soluble organic solvents, and alcohols It is also possible to use an aqueous solution added in an amount of about 0.01 to 10% by weight.

The temperature of the swelling bath 13 is 10-50 degreeC, for example, Preferably it is 10-40 degreeC, More preferably, it is 15-30 degreeC. The immersion time of the raw film 10 becomes like this. Preferably it is 10-300 second, More preferably, it is 20-200 second. Moreover, when the raw film 10 is the polyvinyl alcohol-type resin film stretched|stretched in base|substrate beforehand, the temperature of the swelling bath 13 is 20-70 degreeC, for example, Preferably it is 30-60 degreeC. The immersion time of the raw film 10 becomes like this. Preferably it is 30 to 300 second, More preferably, it is 60 to 240 second.

In a swelling process, it is easy to produce the problem that the raw film 10 swells in the width direction, and wrinkles enter a film. As one means for conveying the film while removing the wrinkles, a roll having a widening function such as an expander roll, a spiral roll, or a crown roll is used for the guide rolls 30, 31 and/or 32, or a cross guider, bend The use of other widening devices such as bars and tenter clips may be mentioned. Another means for suppressing the occurrence of wrinkles is to apply a stretching treatment. For example, the uniaxial stretching process can be implemented in the swelling bath 13 using the circumferential speed difference of the nip roll 50 and the nip roll 51. As shown in FIG.

In the swelling treatment, since the film swells and expands also in the conveying direction of the film, if active stretching is not performed on the film, in order to eliminate the slack of the film in the conveying direction, for example, it is disposed before and after the swelling bath 13 It is preferable to take measures, such as controlling the speed of the nip rolls 50 and 51. In addition, for the purpose of stabilizing the film transport in the swelling bath 13, the water flow in the swelling bath 13 is controlled by an underwater shower, or an EPC device (Edge Position Control device: detects the end of the film to prevent meandering of the film) It is also useful to use or use a device to prevent it).

In the example shown in FIG. 3, the film taken out from the swelling bath 13 passes through the guide roll 32, the nip roll 51, and the guide roll 33 in order, and is introduce|transduced into the dyeing bath 15.

(dyeing process)

A dyeing process is performed for the objective of adsorb|sucking and orientating a dichroic dye to the polyvinyl alcohol-type resin film after a swelling process. Treatment conditions are determined within a range that can achieve the above object, and within a range in which problems such as extreme dissolution and devitrification of the film do not occur. Referring to FIG. 3, the dyeing process is carried out along a film transport path constructed by the nip roll 51, guide rolls 33 to 36, and the nip roll 52, and the film after swelling treatment is transferred to the dye bath 15 ) (processing liquid accommodated in a dyeing tank) for a predetermined period of time, followed by extraction. In order to increase the dyeability of the dichroic dye, the film provided in the dyeing process is preferably a film subjected to at least uniaxial stretching treatment, or instead of the uniaxial stretching treatment before the dyeing treatment, or in addition to the uniaxial stretching treatment before the dyeing treatment, dyeing It is preferable to perform a uniaxial stretching process at the time of a process.

When iodine is used as the dichroic dye, for example, an aqueous solution having a concentration of iodine/potassium iodide/water = about 0.003 to 0.3/about 0.1 to 10/100 in a weight ratio can be used as the dyeing solution in the dyeing bath 15 . Instead of potassium iodide, other iodides such as zinc iodide may be used, or potassium iodide and other iodides may be used in combination. In addition, you may make it coexist with compounds other than iodide, for example, boric acid, zinc chloride, cobalt chloride, etc. When boric acid is added, it is distinguished from the crosslinking treatment described later in that it contains iodine, and if the aqueous solution contains about 0.003 parts by mass or more of iodine with respect to 100 parts by weight of water, it can be regarded as the dyeing bath 15. can The temperature of the dye bath 15 at the time of immersing a film is 10-45 degreeC normally, Preferably it is 10-40 degreeC, More preferably, it is 20-35 degreeC, The immersion time of a film is 30-600 normally. second, preferably 60 to 300 seconds.

When a water-soluble dichroic dye is used as the dichroic dye, for example, an aqueous solution having a concentration of dichroic dye/water = about 0.001 to 0.1/100 in weight ratio can be used for the dyeing solution in the dyeing bath 15 . In this dyeing bath 15, a dyeing aid etc. may be made to coexist, and inorganic salts, such as sodium sulfate, surfactant, etc. may be contained, for example. A dichroic dye may be used individually by 1 type, and may use 2 or more types of dichroic dye together. The temperature of the dyeing bath 15 at the time of immersing a film is, for example, 20-80 degreeC, Preferably it is 30-70 degreeC, and the immersion time of a film is 30-600 second normally, Preferably it is 60-300 second. .

As described above, in the dyeing step, the film can be uniaxially stretched in the dyeing bath 15 . Uniaxial stretching of a film can be performed according to the method, such as providing a circumferential speed difference between the nip roll 51 and the nip roll 52 arrange|positioned before and behind the dyeing bath 15.

Also in the dyeing treatment, in the same manner as in the swelling treatment, in order to convey the polyvinyl alcohol-based resin film while removing the wrinkles of the film, the guide rolls 33, 34, 35 and/or 36 are provided with expander rolls, spiral rolls, crown rolls and A roll having the same widening function may be used, or another widening device such as a cross guider, bend bar, or tenter clip may be used. Another means for suppressing the generation of wrinkles is to perform an stretching treatment similar to the swelling treatment.

In the example shown in FIG. 3, the film taken out from the dyeing bath 15 passes through the guide roll 36, the nip roll 52, and the guide roll 37 in order, and is introduce|transduced into the crosslinking bath 17a.

(crosslinking process)

A bridge|crosslinking process is a process performed for the objective of the waterproofing by bridge|crosslinking. Referring to Fig. 3, in the crosslinking process, the crosslinking bath 17a (accommodated in the crosslinking bath) is transported along the film transport path constructed by the nip roll 52, guide rolls 37 to 40, and the nip roll 53a. It can carry out by immersing the film after a dyeing process in a crosslinking liquid) for a predetermined time, and then withdrawing it.

As a crosslinking liquid, the solution which melt|dissolved the crosslinking agent in the solvent can be used. As a crosslinking agent, boron compounds, such as boric acid and borax, glyoxal, glutaraldehyde, etc. are mentioned, for example. These may be one type and may use two or more types together. As the solvent, for example, water can be used, and an organic solvent compatible with water may be included. Although the density|concentration of the crosslinking agent in a crosslinking solution is not limited to this, It is preferable to exist in the range of 1-20 mass %, and it is more preferable that it is 3-15 mass %.

The crosslinking solution may be an aqueous solution containing, for example, about 1 to 10 parts by mass of boric acid with respect to 100 parts by mass of water. When the dichroic dye used in the dyeing treatment is iodine, the crosslinking solution preferably contains iodide in addition to boric acid, and the amount thereof can be, for example, 1 to 30 parts by mass relative to 100 parts by mass of water. Potassium iodide, zinc iodide, etc. are mentioned as an iodide. In addition, you may make it coexist with compounds other than iodide, for example, zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate, etc.

In the crosslinking treatment, the concentrations of boric acid and iodide and the temperature of the crosslinking bath 17a can be appropriately changed. The crosslinking solution may be, for example, an aqueous solution having a concentration of boric acid/iodide/water = 3 to 10/1 to 20/100 in a mass ratio. If necessary, other crosslinking agents may be used instead of boric acid, or boric acid and other crosslinking agents may be used in combination. The temperature of the crosslinking bath 17a at the time of immersing a film is 40-70 degreeC normally, Preferably it is 50-65 degreeC, The immersion time of a film is 10-600 second normally, Preferably it is 20-300 second, More preferably, it is 20 to 200 second.

The crosslinking treatment may be performed multiple times, and is usually performed 2 to 5 times. In this case, the composition and temperature of each crosslinking bath to be used may be the same as long as they are within the said range, and may differ.

The uniaxial stretching process can also be performed in the crosslinking bath 17a using the circumferential speed difference of the nip roll 52 and the nip roll 53a.

Also in the crosslinking treatment, in order to convey the polyvinyl alcohol-based resin film while removing the wrinkles of the film in the same way as in the swelling treatment, a roll having a widening function such as an expander roll, a spiral roll, a crown roll is used as a guide roll, or a cross Other widening devices such as guiders, bend bars or tenter clips may be used or may be used. Another means for suppressing the generation of wrinkles is to perform a stretching treatment similar to the swelling treatment.

In the example shown in FIG. 3, the film taken out from the crosslinking bath 17a passes through the guide roll 49 and the nip roll 53a in order, and is introduce|transduced into the complementary color bath 17b.

(Complementary color process)

The complementary color process is a process performed for the purpose of color adjustment. Referring to Fig. 3, in the complementary color process, the nip roll 53a, guide rolls 41 to 44, and the nip roll 53b are conveyed along the film conveying path, and the complementary color bath 17b (in the complementary color tone) is conveyed. It can carry out by immersing the film after a bridge|crosslinking process in the accommodated complementary liquid) for a predetermined time, and then taking it out.

As a complementary color liquid, the solution which melt|dissolved the crosslinking agent in the solvent can be used. As a crosslinking agent, boron compounds, such as boric acid and borax, glyoxal, glutaraldehyde, etc. are mentioned, for example. One type may be sufficient as these, and they may use 2 or more types together. As the solvent, for example, water can be used, but an organic solvent compatible with water may also be included. Although the density|concentration of the crosslinking agent in a complementary color solution is not limited to this, It is preferable to exist in the range of 1-20 mass %, and it is more preferable that it is 6-15 mass %.

The complementary color solution may be an aqueous solution containing, for example, about 1 to 10 parts by mass of boric acid with respect to 100 parts by mass of water. When the dichroic dye used in the dyeing treatment is iodine, the complementary color solution preferably contains iodide in addition to boric acid, and the amount thereof can be, for example, 1 to 30 parts by weight with respect to 100 parts by mass of water. Potassium iodide, zinc iodide, etc. are mentioned as an iodide. In addition, you may make it coexist with compounds other than iodide, for example, zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate, etc.

When iodine is used as the dichroic dye in the complementary color solution, for example, as the complementary color solution, a concentration of boric acid/iodide/water = 1 to 5/0.5 to 30/100 in a weight ratio can be used. The temperature of the complementary color bath 17b at the time of immersing a film is 10-45 degreeC normally, and the immersion time of a film is 1-300 second normally, Preferably it is 2-100 second.

The uniaxial stretching process can also be performed in the complementary color bath 17b using the circumferential speed difference of the nip roll 53a and the nip roll 53b.

Also in the complementary color treatment, in order to convey the polyvinyl alcohol-based resin film while removing the wrinkles of the film in the same way as in the swelling treatment, a roll having a widening function such as an expander roll, a spiral roll, a crown roll is used as a guide roll, or a cross Other widening devices such as guiders, bend bars or tenter clips may be used or may be used. Another means for suppressing the generation of wrinkles is to perform a stretching treatment similar to the swelling treatment.

In the example shown in FIG. 3, the film taken out from the complementary color bath 17b passes through the guide roll 44 and the nip roll 53b in order, and is introduce|transduced into the washing|cleaning bath 19.

(cleaning process)

In the example shown in FIG. 3, the washing|cleaning process after a complementary color process is included. A washing process is performed for the purpose of removing chemical|medical agents, such as excess boric acid and iodine, adhering to the polyvinyl alcohol-type resin film. The washing step is performed, for example, by immersing the polyvinyl alcohol-based resin film subjected to the complementary color treatment in the washing bath 19 . In addition, instead of the process of immersing a film in the washing|cleaning bath 19, the washing|cleaning process can also be performed by spraying a washing|cleaning liquid as a shower with respect to the film, or by combining immersion in the washing|cleaning bath 19 and spraying of a washing|cleaning liquid.

Fig. 3 shows an example in which the polyvinyl alcohol-based resin film is immersed in the washing bath 19 to perform the washing treatment. The temperature of the washing|cleaning bath 19 in a washing|cleaning process is 2-40 degreeC normally, and the immersion time of a film is 2-120 second normally.

Also in the washing treatment, for the purpose of conveying the polyvinyl alcohol-based resin film while removing wrinkles, a roll having a widening function such as an expander roll, a spiral roll, or a crown roll is used as a guide roll, or a cross guider, a bend bar Alternatively, other widening devices such as tenter clips may be used. Moreover, in a film washing process, in order to suppress generation|occurrence|production of wrinkles, you may perform an extending|stretching process.

(Stretching process)

As described above, the raw film 10 is subjected to a wet or dry uniaxial stretching treatment during the series of treatment steps (ie, before and after any one or more treatment steps and/or during any one or more treatment steps). A specific method of the uniaxial stretching treatment is, for example, inter-roll stretching in which longitudinal uniaxial stretching is performed with a circumferential speed difference between two nip rolls constituting a film transport path (eg, two nip rolls disposed before and after a treatment bath), Japan It may be a hot roll stretching, a tenter stretching, etc. as described in Patent No. 2731813, Preferably it is roll-to-roll stretching. A uniaxial stretching process can be implemented over multiple times during the time of obtaining the polarizer 23 from the raw film 10. As mentioned above, an extending|stretching process is advantageous also for suppression of generation|occurrence|production of the wrinkles of a film.

The final cumulative draw ratio of the polarizing film 23 on the basis of the raw film 10 is 4.5-7 times normally, Preferably it is 5-6.5 times. An extending process may be performed by any treatment process, and also when extending|stretching by two or more treatment processes, an extending process may be performed by any treatment process.

(drying process)

It is preferable to perform the process of drying a polyvinyl alcohol-type resin film after a washing|cleaning process. Although drying in particular of a film is not restrict|limited, Like the example shown in FIG. 3, it can perform using the drying furnace 21. As shown in FIG. The drying furnace 21 can be provided with a hot air dryer, for example. The drying temperature is, for example, 30 to 100°C, and the drying time is, for example, 30 to 600 seconds. The process of drying a polyvinyl alcohol-type resin film can also be performed using a far-infrared heater. The thickness of the polarizer 23 obtained by making it above is 7 micrometers or more and 30 micrometers or less, for example.

The obtained polarizer may be wound up sequentially on a winding roll, and it may be made into roll form, and it can also provide to a polarizing plate manufacturing process (a process of laminating|stacking a protective film etc. on the single side|surface or both surfaces of a polarizer) as it is without winding up.

<Control of absorbance characteristics of polarizing plate>

When the polarizer 5 is obtained according to the above manufacturing methods, and then the polarizing plate 1 which has a double-sided protective film or the polarizing plate 2 which has a single-sided protective film is produced, various processes in the said manufacturing method contains several factors affecting the absorbance A ₄₅₀ and absorbance A ₇₅₀ of the polarizing plates 1 and 2 and suppression of the change in the degree of polarization before and after the heat resistance test. The main example is in the manufacturing method of the polarizer 5

a) the concentration of potassium iodide in the crosslinking solution used for the crosslinking treatment;

b) the concentration of potassium iodide in the complementary color solution used for the complementary color treatment;

c) the draw ratio of the polyvinyl alcohol-based resin film, the neck-in ratio at the time of stretching, the stretching temperature,

d) the temperature of the washing bath in the washing process, the immersion time in the washing bath,

e) drying temperature in the drying process, drying time,

and the like.

Among the above, in particular, b) and e) exert an influence on the absorbance _A450 and absorbance _A750 of the polarizing plates 1 and 2, and suppression of the change in the degree of polarization before and after the heat resistance test.

Specifically, with respect to b), the concentration of potassium iodide in the complementary color solution is preferably 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight, still more preferably based on 100 parts by weight of water. 1.5 to 2.5 parts by mass. Moreover, with respect to said e), Preferably the drying temperature is 70-100 degreeC, More preferably, it is 80-100 degreeC. In addition, the thickness of the polarizer also exerts an influence on the absorbance A ₄₅₀ and the absorbance A ₇₅₀ of the polarizing plates 1 and 2 and suppression of the change in the degree of polarization before and after the heat resistance test.

<Circular Polarizer>

(1) Basic composition of circular polarizer

4 is one embodiment of the polarizing plate of the present invention. The polarizing plate (hereinafter, sometimes referred to as circularly polarizing plate 1') described in FIG. 4 is on the opposite side to the polarizer 5 of the second protective film 4 in addition to the element of the polarizing plate 1 shown in FIG. 1 . It further has a stacked first retardation layer (8). The 2nd protective film 4 and the 1st retardation layer 8 may be joined through an adhesive bond layer, and description of the above-mentioned 1st and 2nd adhesive bond layer is used as an adhesive bond layer used here.

5 : is one form of the polarizing plate of this invention. The polarizing plate (hereinafter, sometimes referred to as circularly polarizing plate 2') described in FIG. 5 is on the opposite side to the first protective film 10 of the polarizer 5 in addition to the elements of the polarizing plate 2 shown in FIG. 2 . It further has a first retardation layer 30 laminated on the . The polarizer 5 and the 1st retardation layer 30 may be bonded together via an adhesive bond layer, and description of the 1st and 2nd adhesive bond layer mentioned above is used as an adhesive bond layer used here.

Definitions of terms and symbols used in the description of the circularly polarizing plate in this specification are as follows.

(refractive index (nx, ny, nz))

"nx" is the refractive index in the direction (ie, slow axis direction) in which the in-plane refractive index is maximum, "ny" is the direction orthogonal to the slow axis in the plane, and "nz" is the refractive index in the thickness direction.

(In-plane phase difference value)

The in-plane retardation value Re(λ) refers to the in-plane retardation value of the film at 23°C and a wavelength λ (nm). Re(λ) is when the thickness of the film is d(nm),

Re(λ)=(nx-ny)×d

saved according to Re(550) represents the in-plane retardation value of the film in light with a wavelength of 550 nm.

(Phase difference value in the thickness direction)

The retardation value in the thickness direction (thickness direction retardation value; Rth(λ)) means the retardation value in the thickness direction of the film in light of 23°C and wavelength λ(nm). Rth (λ) is when the thickness of the film is d (nm),

Rth(λ)=((nx+ny)/2-nz)×d

saved according to Rth(550) represents the thickness direction retardation value of the film in the light of wavelength 550nm.

(2) first retardation layer

The first retardation layer (the first retardation layer 8 in Figs. 4 and 5) in the circularly polarizing plates 1' and 2' is a layer that converts linearly polarized light into circularly polarized light. As the in-plane retardation value Re1 (550) of the first retardation layer, one satisfying the following formula (a) is used, and preferably, one satisfying the following formula (a1) is used. The material of the 1st retardation layer is not specifically limited.

110 nm ≤ Re1(550) ≤ 160 nm (a)

120 nm ≤ Re1(550) ≤ 150 nm (a1)

The first retardation layer satisfies the formula (a), and is also referred to as a λ/4 retardation layer. The circularly polarizing plate may be configured to include a λ/2 retardation layer (hereinafter also referred to as a “second retardation layer”) that satisfies the formula (d) described later along with the λ/4 retardation layer. Hereinafter, a circularly polarizing plate having a λ/4 phase difference and not including a λ/2 phase difference layer (hereinafter referred to as a “first aspect”) will be described. A circularly polarizing plate having a λ/2 phase difference layer together with a λ/4 phase difference layer (hereinafter referred to as a “second aspect”) will be described later as another aspect of the circularly polarizing plate.

1st aspect WHEREIN: It is preferable that the angle which the 1st retardation layer makes between the slow axis and the direction of the absorption axis of the polarizer 5 is about 45 degrees. Here, "approximately 45 degrees" is not limited to the case of "45 degrees" strictly, but the case of being in the range of "45 degrees ± 5 degrees" is included.

1st aspect WHEREIN: The 1st retardation layer uses the thing whose wavelength dispersion of in-plane retardation value Re1 (λ) satisfies the following formulas (b) and (c).

Re1(450)/Re1(550)≤1.00 (b)

1.00≤Re1(650)/Re1(550) (c)

As the first retardation layer, a retardation film (commercially available) readily available in the market may be used as it is. Examples of such commercially available products include "Pure Ace WR-S", "Pure Ace WR-W", "Pure Ace WR-M" manufactured by Teijin Corporation, and "NRF" manufactured by Nitto Denko.

Another example of retardation film is a thing containing the hardened|cured material of a polymeric liquid crystal compound (henceforth "liquid crystal retardation film"). Since a liquid crystal retardation film can implement|achieve a thing as thin as 0.2 micrometer - 10 micrometers in thickness normally, it is preferably used from a viewpoint of thinning a circularly polarizing plate.

The polymerizable liquid crystal compound capable of forming a liquid crystal retardation film is, for example, Japanese Patent Application Laid-Open No. 2009-173893, Japanese Patent Application Laid-Open No. 2010-31223, WO2012/147904, WO2014/10325, and WO2017- Those disclosed in the publication No. 43438 are mentioned. The polymerizable liquid crystal compounds described in these publications are capable of forming a liquid crystal retardation film having reverse wavelength dispersion in which polarization can be uniformly converted in a wide wavelength range.

A method of forming the liquid crystal retardation film will be briefly described. First, a suitable support is prepared. If necessary, after forming an alignment film on such a support, a liquid composition containing a polymerizable liquid crystal compound is coated and dried to form a layer containing a polymerizable liquid crystal compound on the support. A liquid crystal retardation film is formed by, for example, irradiating with light to polymerize the polymerizable liquid crystal compound contained in the layer while the polymerizable liquid crystal compound contained in the layer is aligned in a predetermined direction.

(3) third retardation layer

The circularly polarizing plate of the first aspect may further include a third retardation layer having a refractive index characteristic of nz>nx≥ny. By providing the third retardation layer having such a refractive index characteristic, for example, when used as an antireflection polarizing plate, the angular dependence of the effect of absorbing reflected light is reduced, and with respect to the reflected light reflected at various angles, its emission can be prevented. Because it can, it is preferable. The 3rd retardation layer may be laminated|stacked between the 1st retardation layer 8 and the polarizer 5, and may be laminated|stacked on the opposite side to the polarizer 5 side of the 1st retardation layer 8.

3rd retardation layer WHEREIN: The refractive index may show the relationship of nx=ny. Here, "nx=ny" includes not only the case where nx and ny are strictly the same, but also the case where nx and ny are substantially the same. Specifically, it is preferable that Re(550) is less than 10 nm.

-260 nm - -10 nm are preferable, as for the retardation Rth (550) of the thickness direction of a 3rd retardation layer, -230 nm - 15 nm are more preferable, and -215 nm - -20 nm are still more preferable. Since the said effect becomes remarkable by being in such a range, it is preferable.

The third retardation layer may be formed of any suitable material, and is not particularly limited, but is preferably a retardation layer in which a liquid crystal compound is fixed to homeotropic alignment. The liquid crystal compound capable of homeotropic alignment may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the liquid crystal layer include the liquid crystal compound and the method for forming the liquid crystal compound described in [0020] to [0042] of Japanese Patent Application Laid-Open No. 2002-333642. In this case, 0.1 micrometer - 5 micrometers are preferable and, as for thickness, 0.2 micrometer - 3 micrometers are more preferable.

(4) Another aspect of the circularly polarizing plate

About the circularly-polarizing plate of another aspect (2nd aspect), only the point which differs from the circular-polarizing plate of the 1st aspect mentioned above is demonstrated. The circularly polarizing plate of a 2nd aspect has a 2nd retardation layer between the polarizer 5 and the 1st retardation layer 8 in addition to a 1st retardation layer. If the in-plane retardation value of the second retardation layer is Re2(λ), the second retardation layer uses the in-plane retardation value Re2(550) that satisfies the following formula (d), preferably, the following formula (d1) Use what you are satisfied with. The material of the 2nd retardation layer is not specifically limited, For example, the material illustrated by the 1st retardation layer can be used.

210 nm ≤ Re2(550) ≤ 300 nm (d)

220 nm ≤ Re2(550) ≤ 290 nm (d1)

In the second aspect, the angle between the slow axis and the direction of the absorption axis of the polarizer of the second retardation layer is preferably approximately 15°. In the second aspect, the angle between the slow axis of the first retardation layer and the direction of the absorption axis of the polarizer is preferably approximately 75°. Here, “approximately 15°” and “approximately 75°” are not strictly limited to the cases of “15°” and “75°”, and the ranges of “15°±5°” and “75°±5°” Including my case.

<Circular polarizing plate with adhesive>

The circularly-polarizing plate of this invention can be set as the circularly-polarizing plate which provides an adhesive layer on at least any one surface, and has an adhesive layer. Such an adhesive layer is normally used in order to bond the circularly-polarizing plate of this invention to an image display panel. The adhesive which forms this adhesive layer is not specifically limited, A well-known thing can be used.

As said adhesive layer, what is necessary is just to be excellent in optical transparency and to show adhesive characteristics, such as appropriate wettability, cohesiveness, and adhesiveness, However, The thing excellent in durability etc. is used preferably. Specific examples of the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer include a pressure-sensitive adhesive (also referred to as an acrylic pressure-sensitive adhesive or rubber-based pressure-sensitive adhesive) containing an acrylic resin or a rubber-based resin.

Among the pressure-sensitive adhesives capable of forming the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer formed of the preferred acrylic pressure-sensitive adhesive is not particularly limited, but (meth)butyl acrylate, (meth)ethyl acrylate, (meth)acrylate isooctyl and (meth)acrylic acid A (meth)acrylic acid ester-based resin formed by polymerizing (meth)acrylic acid ester such as 2-ethylhexyl, and a copolymer resin using two or more types of these (meth)acrylic acid esters are preferably used as the base polymer. Moreover, the polar monomer may be copolymerized with these resin. As the polar monomer, for example, (meth)acrylic acid, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 2-hydroxyethyl, (meth)acrylamide, 2-N,N-dimethylaminoethyl (meth)acryl The monomer which has polar functional groups, such as a carboxyl group, a hydroxyl group, an amide group, an amino group, and an epoxy group, called rate and glycidyl (meth)acrylate is mentioned. In addition, the base polymer here means the polymer which is a main component among solid content which comprises an acrylic adhesive. In addition, a crosslinking agent is mix|blended with an acrylic resin with an adhesive normally.

In addition to this, various additives may be mix|blended with an adhesive. Suitable additives are silane coupling agents or antistatic agents. A silane coupling agent is effective in improving the adhesive force with glass. An antistatic agent is effective in reducing or preventing generation|occurrence|production of static electricity.

It is preferable that the thickness of the adhesive layer for bonding to an image display panel shall be 3-50 micrometers. More preferably, it is 5-30 micrometers. Moreover, the circularly-polarizing plate of this invention WHEREIN: You may provide the adhesive layer for bonding with a front plate on the opposite side of the adhesive layer for bonding with an image display panel. Thus, when the adhesive layer is provided on both sides of the circularly-polarizing plate of this invention, it is preferable that the thickness of at least one shall be 3-50 micrometers among two adhesive layers. More preferably, it is 5-30 micrometers.

A peeling film may be bonded to an adhesive layer in order to prevent dust and foreign material from adhering to an adhesive layer normally at the time of transportation etc. normally. When peeling this peeling film, the problem that static electricity generate|occur|produces in an adhesive layer may be produced. For the purpose of preventing such a problem, in some cases, the pressure-sensitive adhesive layer is given appropriate conductivity. In the case where the pressure-sensitive adhesive layer has conductivity, the resistance value may be appropriately selected. For example, it is preferably in the range of 1×10 ⁹ to 1×10 ¹¹ Ω/□.

The formation method of the said adhesive layer which may form in the circularly-polarizing plate of this invention can be performed according to a well-known method.

[Image display device]

The polarizing plate of this invention forms an image display device by bonding to an image display panel. Hereinafter, such an image display apparatus is demonstrated.

A well-known thing can be used irrespective of the kind as an image display apparatus. For example, the polarizing plate of this invention can be used suitably for organic electroluminescent display. The polarizing plate of the present invention can be provided on the visual recognition side of the organic EL display panel so that the first retardation layer is disposed on the organic EL display panel side.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by these examples.

<Example 1>

A transparent, unstretched polyvinyl alcohol-based resin film (PE 60, average degree of polymerization 2400, manufactured by KURARAY) with a length and width of 100 cm, a thickness of 30 μm, and a degree of saponification of 99.9 mol% or more was dissolved in water (deionized water) at 25°C for 1 minute. It was immersed for 20 seconds to swell (swelling process). Thereafter, iodine/potassium iodide/boric acid/water = 0.3/1.2/0.3/100 (mass ratio) was immersed in a dyeing solution at 30° C. for 2 minutes and 30 seconds to dye (dyeing treatment). At this time, in the swelling treatment and the dyeing treatment, the stretching was performed at a draw ratio of 1.56 times and 1.64 times, respectively, and the stretching was performed so that the cumulative draw ratio until the dyeing treatment was completed was 2.56 times.

Then, it was immersed for 26 seconds (first crosslinking treatment) in a crosslinking solution at 54° C. containing a ratio of potassium iodide/boric acid/water = 7.1/1.8/100 (mass ratio), and stretched at a draw ratio of 1.5 times while crosslinking. After that, it was immersed (second crosslinking treatment) for 20 seconds in a crosslinking solution at 54° C. contained in a ratio of potassium iodide/boric acid/water = 7/3.4/100 (mass ratio), and stretched at a draw ratio of 1.6 times while crosslinking. Subsequently, in the complementary color process, it extended|stretched 1.01 times, immersing for 10 second in the 40 degreeC aqueous solution for complementary colors contained in the ratio of potassium iodide/boric acid/water=1.5/3.4/100 (mass ratio) (complementary color process). At this time, the total cumulative draw ratio of the swelling treatment, the dyeing treatment, the crosslinking treatment, and the complementary color treatment was made to be 5.9 times.

After completion of the complementary color treatment, water was washed with 6°C pure water for 7 seconds to remove foreign substances adhering to the surface of the polarizer (washing treatment). After water washing was completed, the polarizer was dried at the temperature of Table 1 below (drying process), and the polarizer was manufactured.

The obtained polarizer was subjected to a triacetyl cellulose film (trade name "DSG17Z" manufactured by Dainippon Printing Co., Ltd.) as a first protective film on one side using a water-based adhesive, and a second protective film (manufactured by FUJIFILM Corporation) on the other side. After bonding the triacetyl cellulose film of zero retardation "ZRT"), it was dried at 80° C. for 5 minutes to prepare a polarizing plate.

The said water-based adhesive agent was produced by the following means. Polyvinyl alcohol powder (trade name "KL-318" manufactured by Kuraray Co., Ltd., average degree of polymerization 1800) was dissolved in hot water at 95°C to prepare an aqueous polyvinyl alcohol solution having a concentration of 3 wt%. A crosslinking agent (trade name "Sumirez Resin 650" manufactured by Daoka Chemical Industry Co., Ltd.) was mixed with the obtained aqueous solution in a ratio of 1 part by weight with respect to 2 parts by weight of polyvinyl alcohol powder to obtain a water-based adhesive.

<Example 2, Comparative Example 1>

In Example 2 and Comparative Example 1, the weight part of potassium iodide in 100 parts by weight of water of the complementary color solution used in the complementary color treatment and the temperature in the drying treatment were changed as described in Table 1 below, and the first protection A polarizer and a polarizing plate were manufactured in the same manner as in Example 1, except that a triacetyl cellulose film (manufactured by Dainippon Printing Co., Ltd., reflectance 0.1%, trade name "LQ9") was used as a film.

<Evaluation Test>

(1) Measurement of orthogonal b

After cutting the polarizing plates prepared in Examples and Comparative Examples to a size of 4 cm x 4 cm, orthogonal b was measured with an ultraviolet and visible light spectrometer (V-7100 manufactured by JASC). Table 1 shows the results.

(2) Measurement of polarization degree

After cutting the polarizing plates prepared in Examples and Comparative Examples to a size of 4 cm × 4 cm, the visibility corrected polarization degree and the visibility corrected single transmittance (Ty) were measured by an ultraviolet and visible light spectrometer (V-7100, manufactured by JASC). measured. Thereafter, after being put in an oven at 80° C. for 250 hours, the visibility corrected polarization degree was measured according to the same method. The absolute value of the difference in visibility correction|amendment polarization degree before and behind permeation|transmission through oven was made into (DELTA)Py. From the viewpoint of providing a polarizing plate having excellent heat resistance, ΔPy is preferably 0.3 or less. Table 1 shows the results.

(3) Measurement of absorbance

With respect to the polarizing plates manufactured in Examples and Comparative Examples, using an ultraviolet and visible spectrometer (V-7100 manufactured by JASC), absorbance A ₄₅₀ at a wavelength of 450 nm, absorbance A ₇₀₀ at a wavelength of 700 nm, and a wavelength of 750 nm Absorbance A ₇₅₀ at was measured. Table 1 shows the results.

1, 2 polarizing plates, 1', 2' circularly polarizing plates, 3 first protective film, 4 second protective film, 5 polarizer, 6 first adhesive layer, 7 second adhesive layer, 8 first retardation layer (λ/4 retardation) layer), 10 raw film containing polyvinyl alcohol-based resin, 11 fabric roll, 13 swelling bath, 15 dyeing bath, 17a crosslinking bath, 17b complementary color bath, 19 washing bath, 21 drying furnace, 23 polarizer, 30-48, 60, 61 guide rolls, 50-52, 53a, 53b, 54, 55 nip rolls.

Claims (9)

including a polarizer,
Absorbance A ₄₅₀ at a wavelength of 450 nm satisfies the following relational expression (1),
A polarizing plate whose absorbance A ₇₅₀ at a wavelength of 750 nm satisfies the following relational expression (2).
1.6≤A ₄₅₅ ≤2.7 (1)
0.7≤A ₇₅₀ ≤2.3 (2) The polarizing plate according to claim 1, wherein the absorbance A ₇₀₀ at a wavelength of 700 nm satisfies the following relational expression (3).
1.7≤A ₇₀₀ ≤4.5 (3) The polarizing plate according to claim 1 or 2, wherein the b-value of the orthogonal color is -1.5 or less. The polarizing plate according to claim 3, wherein the orthogonal color has a b-value of -20 or more. The polarizing plate according to any one of claims 1 to 4, wherein the polarizer has a thickness of 7 µm or more and 30 µm or less. The polarizing plate according to any one of claims 1 to 5, further comprising a protective film bonded to at least one surface of the polarizer. The polarizing plate according to any one of claims 1 to 6, further comprising a λ/4 retardation layer. The polarizing plate according to claim 7, wherein the polarizing plate is used by being disposed on the viewer side surface of the organic EL display panel. An organic EL display panel comprising an organic EL display panel and the polarizing plate according to claim 8 .

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