KR102408789B1 - Polarizer - Google Patents

Abstract

It is excellent in the adhesiveness of a resin layer and a polarizer, and suppresses generation|occurrence|production of the crack with respect to a polarizer. The polarizing plate 10 has a retardation layer 3 and a polarizer 1, and the retardation layer 3 and the polarizer 1 are laminated with an easily adhesive layer 2 interposed therebetween, and at 85° C. of the easily adhesive layer 2 has a storage modulus of 1.0×10 ⁶ Pa to 1.0×10 ⁷ Pa.

Description

Polarizer

The present invention relates to a polarizing plate.

As a manufacturing method of a polarizing plate used for a liquid crystal display device and an organic EL display device, a polarizer obtained by stretching and dyeing a polyvinyl alcohol-based resin film is affixed to a film constituting a resin layer such as a retardation layer or a protective layer, a polarizing plate How to do it is known. Moreover, as another manufacturing method of a polarizing plate, the method of forming a polyvinyl alcohol-type resin layer on a resin base material, and making this polyvinyl alcohol-type resin layer into a polarizer by extending|stretching and dyeing this laminated body has been proposed.

As described above, the polarizer may be used in a state of being laminated on a resin layer such as a retardation layer or a protective layer. Therefore, it is calculated|required that a polarizer and a resin layer have sufficient adhesive force so that a polarizer may not peel from a resin layer at the time of use of a polarizing plate.

In Patent Document 1, in a manufacturing method for obtaining a polarizing plate from a laminate of a resin substrate and a polyvinyl alcohol-based resin layer, in order to secure sufficient adhesion between the resin substrate and the polyvinyl alcohol-based resin layer, the resin substrate and the polyvinyl alcohol-based resin layer It has been proposed to laminate the resin layer via an easily adhesive layer containing a polyvinyl alcohol-based material.

Japanese Patent Publication No. 4950357

However, the polarizing plate manufactured by the method of patent document 1 has insufficient adhesiveness between a polarizer and a resin layer (resin base material).

This invention is made|formed in view of said subject, The objective is to provide the polarizing plate which is excellent in the adhesiveness of a resin layer and a polarizer, and can suppress generation|occurrence|production of the crack with respect to a polarizer.

The polarizing plate of the present invention has a resin layer and a polarizer, the resin layer and the polarizer are laminated through an easily adhesive layer, and the storage elastic modulus at 85°C of the easily adhesive layer is 1.0×10 ⁶ Pa to 1.0×10 ⁷ Pa to be.

In one embodiment, the storage elastic modulus in 85 degreeC of the said easily adhesive layer after heating under the conditions of 80 degreeC and 500 hours in crosslinking agent presence is 1.0x10 ⁶ Pa - ^1.0x107 Pa.

In one embodiment, the said easily adhesive layer contains a polyolefin-type component and a polyvinyl alcohol-type component.

In one embodiment, the mass ratio of the said polyolefin-type component and the said polyvinyl alcohol-type component is 98:2 - 90:10.

In one embodiment, the thickness of the said easily bonding layer is 500 nm - 1 micrometer.

In one embodiment, the said easily bonding layer and the said polarizer are bonded together through the adhesive agent containing polyvinyl alcohol-type resin.

In one embodiment, the said resin layer is a retardation layer which has an in-plane retardation.

In one embodiment, the in-plane retardation Re(550) of the retardation layer is 100 nm to 180 nm, and the relation of Re(450)<Re(550) is satisfied.

In one embodiment, the angle between the absorption axis of the polarizer and the slow axis of the retardation layer is 38° to 52°.

In one embodiment, the said resin layer is a protective layer which has optical isotropy.

ADVANTAGE OF THE INVENTION According to this invention, it is excellent in the adhesiveness of a resin layer and a polarizer, and the polarizing plate which can suppress generation|occurrence|production of the crack with respect to a polarizer is provided.

1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described, this invention is not limited to these embodiment.

(Definition of terms and symbols)

Definitions of terms and symbols in this specification are as follows.

(1) refractive index (nx, ny, nz)

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

(2) In-plane phase difference (Re)

'Re(λ)' is an in-plane retardation measured with light having a wavelength of λ nm at 23°C. Re(λ) can be obtained by the formula: Re=(nx-ny)×d when the thickness of the layer (film) is d(nm). For example, 'Re(550)' is an in-plane retardation measured with light having a wavelength of 550 nm at 23°C.

A. Polarizer

The polarizing plate of this invention has a resin layer and a polarizer, and the resin layer and a polarizer are adhere|attached through an easily adhesive layer. The polarizing plate has a storage elastic modulus at 85° C. of the easily adhesive layer of 1.0×10 ⁶ Pa or more. Thereby, it can be set as the polarizing plate which is excellent in the adhesiveness of a resin layer and a polarizer, and can suppress generation|occurrence|production of the crack with respect to a polarizer.

In one embodiment of the present invention, the resin layer is a retardation layer having an in-plane retardation. In another embodiment of the present invention, the resin layer may be a protective layer (a protective film or inner protective layer described later) of the polarizer. Hereinafter, a polarizing plate in which the resin layer is a retardation layer will be mainly described.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of the polarizing plate which concerns on one Embodiment of this invention. As shown in FIG. 1 , the polarizing plate 10 has a retardation layer 3 as a resin layer, and the retardation layer 3 and the polarizer 1 are laminated through an easily adhesive layer 2 . In addition, the polarizing plate 10 may have a protective film (not shown) on the opposite side to the retardation layer 3 of the polarizer 1 .

B. Polarizer

As the polarizer 1, any suitable polarizer may be employed. For example, a single-layered resin film may be sufficient as the resin film which forms a polarizer, and the laminated body of two or more layers may be sufficient as it.

As a specific example of the polarizer composed of a single-layer resin film, a polyvinyl alcohol (PVA)-based film, a partially formalized PVA-based film, an ethylene/vinyl acetate copolymer-based partially saponified film, etc. polyene-based oriented films such as those subjected to dyeing treatment and stretching treatment with a dichroic substance of PVA, dehydration treatment products of PVA and dehydrochloric acid treatment products of polyvinyl chloride. Preferably, from the viewpoint of excellent optical properties, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching is used.

The dyeing with iodine is made by, for example, immersing a PVA-based film in an aqueous iodine solution. Preferably the draw ratio of the said uniaxial stretching is 3-7 times. Extending|stretching may be performed after a dyeing process, and may be performed, dyeing|staining. Moreover, you may dye|dye after extending|stretching. If necessary, the PVA-based film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, and the like. For example, by immersing the PVA-based film in water and washing with water before dyeing, it is possible to not only wash the surface of the PVA-based film from contamination and anti-blocking agent, but also to swell the PVA-based film to prevent staining of dyeing.

As a specific example of a polarizer obtained using a laminate, a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and a PVA-based resin layer coated on the resin substrate The polarizer obtained using a laminated body is mentioned. A polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate is applied, for example, by applying a PVA-based resin solution to the resin substrate and drying the resin substrate to form a PVA-based resin layer on the resin substrate. obtaining a laminate of a base material and a PVA-based resin layer; It can be produced by; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer. In this embodiment, extending|stretching includes extending|stretching by immersing a laminated body in boric-acid aqueous solution typically. In addition, the stretching may further include air stretching the laminate at a high temperature (eg, 95° C. or higher) before stretching in an aqueous boric acid solution, if necessary. The obtained laminate of the resin substrate/polarizer may be used as it is (that is, the resin substrate may be an inner protective layer provided between the retardation layer and the polarizer), or the laminate of the resin substrate/polarizer may be used as a resin substrate ( The resin layer) may be peeled off, and any appropriate protective layer according to the purpose may be laminated on the peeled surface as an inner protective layer to be used. The detail of the manufacturing method of such a polarizer is described in Unexamined-Japanese-Patent No. 2012-73580, for example. This publication is incorporated herein by reference in its entirety. In addition, when using a resin base material as an inner side protective layer provided between a retardation layer and a polarizer, you may provide an easily adhesive layer between a resin base material and a PVA-type resin layer. In addition, when peeling a resin base material and laminating|stacking any suitable protective layer according to the objective on the said peeling surface as an inner side protective layer, you may provide an easily adhesive layer between an inner side protective layer and a polarizer.

The thickness of the polarizer can be appropriately designed according to the purpose and use, and is preferably 3 µm to 25 µm.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizer is preferably 42.0% to 46.0%, more preferably 44.5% to 46.0%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.

C. retardation layer

The retardation layer 3 may be composed of a retardation film having any suitable optical and/or mechanical properties depending on the purpose. The retardation layer 3 typically has a slow axis. In one embodiment, the angle θ between the slow axis of the retardation layer 3 and the absorption axis of the polarizer 1 is preferably 38° to 52°, more preferably 42° to 48°, , more preferably about 45°. If the angle θ is within such a range, the polarizing plate 10 having extremely excellent circular polarization characteristics can be obtained by using the retardation layer 3 as a λ/4 plate.

The retardation layer 3 preferably exhibits a relationship of refractive index characteristics of nx>ny≥nz. The retardation layer 3 is typically provided in order to impart antireflection properties to the polarizing plate, and can function as a λ/4 plate in one embodiment. In this case, the in-plane retardation Re(550) of the retardation layer 3 is preferably 80 nm to 200 nm, more preferably 100 nm to 180 nm, still more preferably 110 nm to 170 nm. In addition, 'ny=nz' includes not only the case where ny and nz are completely the same, but also the case where 'ny=nz' is substantially the same. Therefore, there may be a case where ny<nz is not impaired in the effect of the present invention.

The birefringence (Δn _xy ) of the retardation layer 3 is, for example, 0.0025 or more, and preferably 0.0028 or more. On the other hand, the upper limit of the birefringence (Δn _xy ) is, for example, 0.0060, preferably 0.0050. By optimizing the birefringence in such a range, it is possible to obtain the retardation layer 3 which is thin and has desired optical properties.

The Nz coefficient of the retardation layer 3 is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3. By satisfying such a relationship, when the obtained polarizing plate is used for an image display apparatus, the very excellent reflection color can be achieved.

The retardation layer 3 may exhibit an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, or may exhibit a positive wavelength dispersion characteristic in which the phase difference value decreases according to the wavelength of the measurement light, and the phase difference value is the wavelength of the measurement light It may exhibit a flat wavelength dispersion characteristic which hardly changes even with this. In one embodiment, the retardation layer 3 exhibits an inverse dispersion wavelength characteristic. In this case, the retardation layer 3 satisfies the relationship of Re(450)<Re(550), and Re(450)/Re(550) of the retardation layer 3 is preferably 0.8 or more and less than 1. Preferably it is 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection properties can be realized. In another embodiment, the retardation layer 3 shows a flat wavelength dispersion characteristic. In this case, Re(450)/Re(550) of the retardation layer 3 is preferably 0.99 to 1.03, and Re(650)/Re(550) is preferably 0.98 to 1.02. In this case, the retardation layer 3 may have a stacked structure. Specifically, by arranging the retardation film functioning as the λ/2 plate and the retardation film functioning as the λ/4 plate at a predetermined axial angle (eg, 50° to 70°, preferably about 60°), the ideal reverse wavelength It is possible to obtain a characteristic close to the dispersion characteristic, and as a result, an extremely excellent antireflection characteristic can be realized.

The retardation layer 3 has a water absorption of 3% or less, preferably 2.5% or less, and more preferably 2% or less. By satisfying such a water absorption rate, it is possible to suppress a change in display characteristics with the passage of time. In addition, water absorption can be calculated|required based on JISK7209.

The retardation layer 3 has an absolute value of the photoelastic coefficient of preferably 2×10 ^-11 m ² /N or less, more preferably 2.0×10 ^-13 m ² /N to 1.6×10 ^-11 m ² /N contains resin. If the absolute value of the photoelastic coefficient is within such a range, a phase difference change is unlikely to occur when a shrinkage stress during heating occurs. As a result, thermal non-uniformity of the obtained image display apparatus can be prevented favorably.

The thickness of the retardation layer 3 is, for example, 70 µm or less, preferably 40 µm to 60 µm. If it is such a thickness, suitable mechanical strength can be provided as a protective layer of a polarizer.

The retardation layer 3 may be composed of any suitable resin film capable of satisfying the above characteristics. Representative examples of such resins include cyclic olefin-based resins, polycarbonate-based resins, cellulose-based resins, polyester-based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, and polystyrene-based resins. , and acrylic resins. When the retardation layer 3 is made of a resin film exhibiting reverse dispersion wavelength characteristics, a polycarbonate-based resin may be preferably used.

Any suitable polycarbonate resin can be used as said polycarbonate resin, as long as the effect of this invention can be acquired. Preferably, the polycarbonate resin comprises a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and an alicyclic diol, alicyclic dimethanol, di, tri or polyethylene glycol. and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alkylene glycol or spiroglycol. Preferably, the polycarbonate resin has a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from alicyclic dimethanol and/or di, tri or a structural unit derived from polyethylene glycol; More preferably, a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di, tri or polyethylene glycol are included. Polycarbonate resin may contain the structural unit derived from another dihydroxy compound as needed. In addition, details of the polycarbonate resin that can be preferably used in the present invention are described in, for example, Japanese Patent Application Laid-Open Nos. 2014-10291 and 2014-26266, the description of which is incorporated herein by reference. is used as

In one embodiment, a polycarbonate-based resin including a unit structure derived from a dihydroxy compound represented by the following formula (1) may be used.

[Formula (1)]

(In the formula (1), R ₁ to R ₄ are each independently a hydrogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 cycloalkyl group, or a substituted or an unsubstituted C6-C20 aryl group, X is a substituted or unsubstituted C2-C10 alkylene group, a substituted or unsubstituted C6-C20 cycloalkylene group, or a substituted or unsubstituted represents an arylene group having 6 to 20 carbon atoms, and m and n are each independently an integer of 0 to 5.)

Specific examples of the dihydroxy compound represented by the formula (1) include 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9,9 -bis(4-hydroxy-3-ethylphenyl)fluorene, 9,9-bis(4-hydroxy-3-n-propylphenyl)fluorene, 9,9-bis(4-hydroxy-3- Isopropylphenyl)fluorene, 9,9-bis(4-hydroxy-3-n-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3-sec-butylphenyl)fluorene, 9 ,9-bis(4-hydroxy-3-tert-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3-cyclohexylphenyl)fluorene, 9,9-bis(4-hydroxyl -3-phenylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-methylphenyl ) Fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isopropylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-iso Butylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)- 3-cyclohexylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy) -3,5-dimethylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butyl-6-methylphenyl)fluorene, 9,9-bis(4-( 3-hydroxy-2,2-dimethylpropoxy)phenyl)fluorene etc. are mentioned.

The polycarbonate-based resin is isosorbide, isomannide, isoidide, spiro glycol, dioxane glycol, diethylene glycol (DEG), triethylene glycol (TEG), polyethylene in addition to the structural unit derived from the dihydroxy compound. The structural unit derived from dihydroxy compounds, such as glycol (PEG) and bisphenol, may be included.

Details of the polycarbonate-based resin including a structural unit derived from a dihydroxy compound are described in, for example, Japanese Patent No. 5204200, Japanese Patent Application Laid-Open No. 2012-67300, Japanese Patent No. 3325560, WO2014/061677, etc. have. The description of this patent document is incorporated herein by reference.

In one embodiment, a polycarbonate-based resin including an oligofluorene structural unit may be used. Examples of the polycarbonate-based resin containing an oligofluorene structural unit include a resin containing a structural unit represented by the following general formula (2) and/or a structural unit represented by the following general formula (3).

[Formula (2)]

[Formula (3)]

(In the formulas (2) and (3), R ₅ and R ₆ are each independently a direct bond, a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms (preferably, 2 to 3 carbon atoms in the main chain) alkylene group).R ₇ is a direct bond, substituted or unsubstituted alkylene group having 1 to 4 carbon atoms (preferably an alkylene group having 1 to 2 carbon atoms on the main chain). R ₈ to R ₁₃ are each independently; A hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms (preferably 1 to 4, more preferably 1 to 2), or a substituted or unsubstituted alkyl group having 4 to 10 carbon atoms (preferably 4 to 8, more preferably 4 to 8 carbon atoms) Preferably 4-7) aryl group, substituted or unsubstituted C1-C10 (preferably 1-4, more preferably 1-2) acyl group, substituted or unsubstituted C1-C10 (preferably Preferably 1 to 4, more preferably 1 to 2) an alkoxy group, a substituted or unsubstituted aryloxy group having 1 to 10 carbon atoms (preferably 1 to 4, more preferably 1 to 2), a substituted or An unsubstituted C1-C10 (preferably 1-4, more preferably 1-2) acyloxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted C1-C10 (preferably 1-C10) 4) a vinyl group, a substituted or unsubstituted ethynyl group having 1 to 10 (preferably 1 to 4) carbon atoms, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group or a cyano group. At least two adjacent groups among ₈ to R ₁₃ may be bonded to each other to form a ring.)

In one embodiment, the fluorene ring contained in the oligofluorene structural unit has a structure in which all of R ₈ to R ₁₃ are hydrogen atoms, or R ₈ and/or R ₁₃ is a halogen atom, an acyl group; It is any one selected from the group which consists of a nitro group, a cyano group, and a sulfo group, and has a structure in which R< ₉ >-R< ₁₂ > is a hydrogen atom.

Details of the polycarbonate-based resin including the oligofluorene structural unit are described in, for example, Japanese Patent Application Laid-Open No. 2015-212816. The description of this patent document is incorporated herein by reference.

It is preferable that the glass transition temperature of the said polycarbonate resin is 110 degreeC or more and 150 degrees C or less, More preferably, they are 120 degreeC or more and 140 degrees C or less. When the glass transition temperature is excessively low, heat resistance tends to deteriorate, there is a possibility that a dimensional change is caused after film forming, and the image quality of the image display device obtained may be lowered. When the glass transition temperature is excessively high, the molding stability at the time of film molding may deteriorate, and the transparency of the film may be impaired. In addition, a glass transition temperature can be calculated|required according to JISK7121 (1987).

The molecular weight of the polycarbonate resin may be expressed as reduced viscosity. Reduced viscosity is measured by using methylene chloride as a solvent, precisely preparing polycarbonate concentration to 0.6 g/dL, and using an Uberode viscosity tube at a temperature of 20.0°C±0.1°C. As for the lower limit of reduced viscosity, 0.30 dL/g is preferable normally, More preferably, it is 0.35 dL/g or more. As for the upper limit of reduced viscosity, 1.20 dL/g is preferable normally, More preferably, it is 1.00 dL/g, More preferably, it is 0.80 dL/g. When the reduced viscosity is smaller than the lower limit, a problem may arise that the mechanical strength of the molded article becomes small. On the other hand, when the reduced viscosity is larger than the upper limit, the fluidity at the time of molding decreases, and there are cases where a problem occurs that productivity and moldability decrease.

A commercially available film may be used as the polycarbonate-based resin film. Specific examples of the 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.

The retardation layer 3 is obtained, for example, by stretching a film formed of the polycarbonate-based resin. As a method for forming a film from a polycarbonate-based resin, any suitable molding processing method may be employed. Specific examples include a compression molding method, a transfer molding method, an injection molding method, an extrusion molding method, a blow molding method, a powder molding method, an FRP molding method, a cast coating method (such as a casting method), a calender molding method, and a hot pressing method. An extrusion molding method or a cast coating method is preferable. It is because the smoothness of the film obtained can be improved and favorable optical uniformity can be acquired. Molding conditions can be appropriately set according to the composition or type of the resin used, characteristics desired for the retardation layer 3, and the like. In addition, as mentioned above, since many film products are marketed as for polycarbonate-type resin, you may use the said commercial film for a extending|stretching process as it is.

The thickness of the resin film (unstretched film) may be set to any appropriate value depending on the desired thickness of the retardation layer, desired optical properties, stretching conditions described later, and the like. Preferably it is 50 micrometers - 300 micrometers.

For the above stretching, any suitable stretching method and stretching conditions (eg, stretching temperature, stretching ratio, stretching direction) may be employed. Specifically, it is possible to use various stretching methods such as free-end stretching, fixed-end stretching, free-end contraction, fixed-end contraction, etc. alone, simultaneously or sequentially. The stretching direction can also be carried out in various directions or dimensions, such as the longitudinal direction, the width direction, the thickness direction, and the oblique direction. It is preferable that the temperature of extending|stretching is Tg-30 degreeC - Tg+60 degreeC with respect to the glass transition temperature (Tg) of a resin film, More preferably, they are Tg-10 degreeC - Tg+50 degreeC.

By appropriately selecting the stretching method and stretching conditions, a retardation film having the desired optical properties (eg, refractive index characteristic, in-plane retardation, Nz coefficient) can be obtained.

In one embodiment, retardation film is produced by uniaxially stretching a resin film or fixed-end uniaxial stretching. As a specific example of fixed-end uniaxial stretching, the method of extending|stretching in the width direction (transverse direction) is mentioned, running a resin film in a longitudinal direction. The draw ratio is preferably 1.1 to 3.5 times.

In another embodiment, the retardation film can be produced by continuously obliquely stretching a long resin film in the direction of the above-mentioned angle θ with respect to the longitudinal direction. By adopting oblique stretching, a long stretched film having an orientation angle of an angle θ (slow axis in the direction of angle θ) with respect to the longitudinal direction of the film can be obtained, for example, roll-to-roll when laminating with a polarizer This makes it possible to simplify the manufacturing process. Also, the angle θ may be an angle between the absorption axis of the polarizer and the slow axis of the retardation layer in the polarizing plate. As described above, the angle θ is preferably 38° to 52°, more preferably 42° to 48°, and still more preferably about 45°.

D. Easy-to-adhesive layer

The easily adhesive layer 2 is provided in the surface of the phase difference layer 3 by the polarizer 1 side. The polarizing plate 10 is typically manufactured by bonding the retardation layer 3 in which the easily bonding layer 2 was formed on the surface, and a polarizer through an adhesive agent.

As described above, the easily adhesive layer 2 has a storage elastic modulus at 85°C of 1.0×10 ⁶ Pa to 1.0×10 ⁷ Pa. The storage elastic modulus in 85 degreeC of the easily bonding layer 2 becomes like this. Preferably it is 2.0x10 ^{6 Pa - 7.0x10 6 Pa} . Thereby, it can be set as the polarizing plate 10 which is excellent in the adhesiveness of the phase difference layer 3 and the polarizer 1, and can suppress generation|occurrence|production of the crack with respect to the polarizer 1. Hereinafter, it demonstrates concretely. By use of the polarizing plate in a heating environment, the whole resin layer expands, and when a polarizer shrink|contracts, a shear force may be applied to an easily bonding layer. When the storage elastic modulus in 85 degreeC of an easily adhesive layer is less than 1.0x10 ⁶ Pa, an easily adhesive layer is soft and the deformation|transformation with respect to the applied stress is large. Therefore, when a shearing force is applied to an easily bonding layer, the adhesive fall in the interface with the polarizer 1 or the cohesive failure of an easily bonding layer may generate|occur|produce. In particular, when the easily adhesive layer is peeled off at the interface with the polarizer, there may be a problem that the polarizer is exposed and cracks occur in the polarizer. Moreover, when the storage elastic modulus in 85 degreeC of an easily bonding layer is less than 1.0x10 ⁶ Pa, progress of the fine crack which generate|occur|produced in a polarizer may not be suppressed. When the storage elastic modulus in 85 degreeC of an easily bonding layer is larger than 1.0x10 ⁷ Pa, an easily bonding layer is soft, and the function of stress relaxation by an easily bonding layer is insufficient. Therefore, when a shear force is applied to an easily adhesive layer, the adhesive force between a retardation layer and a polarizer falls, As a result, destruction of the retardation layer and/or cohesive failure of an easily adhesive layer may occur. On the other hand, when the storage elastic modulus in 85 degreeC of the easily adhesive layer 2 is 1.0x10 ⁶ Pa to ^1.0x107 Pa, it is excellent in the adhesive force between the retardation layer 3 and the polarizer 1, and retardation layer The polarizing plate 10 which suppressed the fracture|rupture of (3) and/or the cohesive fracture of the easily bonding layer 2 can be obtained.

The storage elastic modulus at 85 degreeC of the easily adhesive layer 2 after heating on conditions of 80 degreeC and 500 hours in crosslinking agent presence becomes like this. Preferably it is 1.0x10< ⁶ >Pa - ^1.0x107Pa . Preferably, the easily adhesive layer 2 has a storage elastic modulus of 1.0×10 ⁶ Pa to 1.0×10 ⁷ Pa before heating at 80° C. for 500 hours at 80° C. in the presence of a cross-linking agent, and at 80° C. for 500 hours in the presence of a cross-linking agent. The storage elastic modulus at 85°C after heating is 1.0×10 ⁶ Pa to 1.0×10 ⁷ Pa. That is, Preferably, in the easily adhesive layer 2, the change amount of the storage elastic modulus in 85 degreeC before and behind heating at 80 degreeC and 500 hours in crosslinking agent presence is 9.0x10< ⁶ >Pa or less. In the case of using a conventional easily adhesive layer made of a polyvinyl alcohol-based component when bonding the retardation layer 3 and the polarizer 1 through an adhesive containing a polyvinyl alcohol-based resin as a main component, the influence of the crosslinking agent contained in the adhesive is By this, crosslinking of the polyvinyl alcohol-based component contained in the easily adhesive layer proceeds, and as a result, the storage elastic modulus of the easily adhesive layer increases over time, and the adhesion between the retardation layer and the polarizer may decrease. On the other hand, by using the easily adhesive layer 2 whose amount of change of the storage elastic modulus in 85 degreeC before and behind 80 degreeC and 500 hours heating in the presence of a crosslinking agent is 9.0x10 ⁶ Pa or less, the retardation layer 3 and the polarizer 1 are attached The temporal raise of the storage elastic modulus of the easily bonding layer 2 after combining can be reduced, and the fall of the adhesiveness of the phase difference layer 3 and the polarizer 1 can be suppressed.

As a constituent material of the easily adhesive layer 2, any suitable material which can make the storage elastic modulus in 85 degreeC within the said range can be employ|adopted. The easily adhesive layer 2 typically contains a polyolefin-based component and a polyvinyl alcohol-based component. In this case, the mass ratio of the polyolefin-based component to the polyvinyl alcohol-based component is preferably 86:14 to 99:1, more preferably 90:10 to 98:2. By adjusting the mass ratio of the polyolefin-based component and the polyvinyl alcohol-based component, the storage elastic modulus at 85° C. of the easily adhesive layer 2 (substantially, the easily adhesive composition forming the easily adhesive layer 2) can be controlled.

The easily adhesive layer 2 is typically formed by apply|coating an easily adhesive agent composition to one side of the retardation layer 3, and drying it. Any suitable method can be employ|adopted as a coating method of the constituent material of an easily bonding layer. For example, the bar coat method, the roll coat method, the gravure coat method, the rod coat method, the slot orifice coat method, the curtain coat method, the fountain coat method etc. are mentioned. As a drying temperature, it is 50 degreeC or more typically, Preferably it is 70 degreeC or more, More preferably, it is 90 degreeC or more. By making the drying temperature into such a range, the polarizing plate excellent in color resistance (in particular under high temperature, high humidity) can be provided. The drying temperature is preferably 120°C or lower, more preferably 100°C or lower.

The thickness of the easily bonding layer 2 can be set to arbitrary appropriate values. The thickness of the easily adhesive layer 2 becomes like this. Preferably it is 500 nm - 1 micrometer, More preferably, it is 700 nm - 800 nm. By setting in such a range, it can be excellent in adhesiveness with the polarizer 1, and it can suppress that retardation is expressed in the easily bonding layer 2.

E. Adhesive layer

The retardation layer 3 and the polarizer 1 are typically bonded together via the adhesive bond layer formed on the easily bonding layer 2 . The adhesive layer may be composed of any suitable adhesive. The thickness of the adhesive layer is preferably 10 nm to 300 nm, more preferably 10 nm to 200 nm, particularly preferably 20 nm to 150 nm.

The adhesive preferably has transparency and optical isotropy. Any suitable one may be employed as the form of the adhesive. Specific examples include water-based adhesives, solvent-based adhesives, emulsion-based adhesives, solvent-free adhesives, active energy ray-curable adhesives, and thermosetting adhesives. Examples of the active energy ray curing adhesive include an electron beam curing adhesive, an ultraviolet curing adhesive, and a visible ray curing adhesive. A water-based adhesive can be preferably used.

Specific examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex-based adhesive, a water-based polyurethane, and an aqueous polyester. Preferably, it is a polyvinyl alcohol-type adhesive agent, such as polyvinyl alcohol or modified polyvinyl alcohol, More preferably, it is an adhesive agent containing polyvinyl alcohol which has an acetoacetyl group as a main component. Such an adhesive is marketed, and the Nippon Synthetic Chemical Co., Ltd. product (brand name "Kosefaimer Z") is mentioned as a specific example of a commercial item.

F. Protective film

The protective film is formed of any suitable film that can be used as a protective film of a polarizer. Specific examples of the material used as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyethersulfone, and polysulfone. Transparent resins, such as a phone type, polystyrene type, polynorbornene type, polyolefin type, (meth)acrylic type, acetate type, etc. are mentioned. Moreover, thermosetting resins, such as (meth)acrylic type, a urethane type, a (meth)acryl urethane type, an epoxy type, a silicone type, or ultraviolet curable resin, etc. are mentioned. In addition to this, for example, glassy polymers, such as a siloxane type polymer, are also mentioned. Further, the polymer film described in Japanese Patent Application Laid-Open No. 2001-343529 (WO01/37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used, for example, isobutene and N- and a resin composition comprising an alternating copolymer composed of methylmaleimide and an acrylonitrile/styrene copolymer. The polymer film may be, for example, an extrusion molding of the resin composition.

The polarizing plate of this invention is typically arrange|positioned on the visual recognition side of an image display apparatus, and the protective film is typically arrange|positioned at the visual recognition side. Accordingly, the protective film may be subjected to surface treatment such as a hard coat treatment, an antireflection treatment, an antistick treatment, and an antiglare treatment, if necessary.

The thickness of the protective film may be any suitable thickness as long as the effect of the present invention can be obtained. The thickness of a protective film is 10 micrometers - 100 micrometers, for example, Preferably they are 30 micrometers - 90 micrometers. In addition, when surface treatment is performed, the thickness of a protective film is the thickness including the thickness of a surface treatment layer.

G. Different protective layers

Another protective layer (inner protective layer) disposed as needed is also formed of any suitable film usable as a protective layer of the polarizer. The material used as the main component of the film is the same as described in the above F item for the protective film. The thickness of the inner protective layer is, for example, 15 µm to 35 µm, preferably 20 µm to 30 µm. The inner protective layer is preferably optically isotropic. In the present specification, "optically isotropic" means that the in-plane retardation Re (550) is 0 nm to 10 nm, and the retardation Rth (550) in the thickness direction is -10 nm to +10 nm.

H. Other

As described above, as an embodiment of the present invention, the polarizing plate 10 in which the resin layer is the retardation layer 3 has been described as an example, but the embodiment of the present invention is not limited thereto. That is, in the polarizing plate of another embodiment of the present invention, the resin layer may be an inner protective layer that can be installed on the retardation layer 3 side of the polarizer 1, and the polarizer 1 and the inner protective layer have an easily adhesive layer interposed therebetween. and may be adhered. In addition, in the polarizing plate of another embodiment of the present invention, the resin layer may be a protective film that can be installed on the opposite side of the retardation layer 3 of the polarizer 1, and the polarizer 1 and the protective film have an easily adhesive layer. You may adhere|attach through it.

I. INDICATORS

The polarizing plate described in the item A to the item H may be applied to a display device such as a liquid crystal display device and an organic EL display device. Accordingly, the present invention includes a display device using the polarizing plate. A display device according to an embodiment of the present invention includes a display element and the polarizing plate according to item A to item H, which is disposed on the viewer side of the display element. The polarizing plate is arrange|positioned so that the retardation layer may become a display element side.

[Example]

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.

<Example 1>

1. Fabrication of polarizer

A polymer film (manufactured by Kuraray Co., Ltd., trade name 'VF-PE #6000') containing a polyvinyl alcohol-based resin having a thickness of 60 µm as a main component was placed in five baths under the conditions (1) to (5) below. It was immersed while applying tension in the longitudinal direction of the film, and stretched so that the final draw ratio was 6.2 times the original length of the film. The polarizer was produced by drying this stretched film for 1 minute in 40 degreeC air circulation type drying oven.

<condition>

(1) Swelling bath: 30 degree pure water.

(2) Dyeing bath: An aqueous solution at 30 degrees containing 0.035 parts by weight of iodine and 0.2 parts by weight of potassium iodide based on 100 parts by weight of water with respect to 100 parts by weight of water.

(3) 1st crosslinking bath: 40 degreeC aqueous solution containing 3 weight% of potassium iodide and 3 weight% of boric acid.

(4) Second crosslinking bath: an aqueous solution at 60 degrees containing 5% by weight of potassium iodide and 4% by weight of boric acid.

(5) Water washing bath: A 25 degree aqueous solution containing 3% by weight of potassium iodide.

2. Preparation of retardation film constituting retardation layer

(Production of polycarbonate resin film)

38.06 parts by weight (0.059 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane and 53.73 parts by weight (0.368 mol) of isosorbide (manufactured by Rocket Fleureth, trade name 'POLYSORB') With 1,4-cyclohexanedimethanol (cis and trans mixture, manufactured by SK Chemicals) 9.64 parts by weight (0.067 mol) and diphenyl carbonate (made by Mitsubishi Chemical) 81.28 parts by weight (0.379 mol) and calcium acetate monohydrate as a catalyst 3.83×10 ⁻⁴ parts ^by weight (2.17×10 ⁻⁶ mol) was charged into the reaction vessel, and the inside of the reaction apparatus was purged with reduced pressure nitrogen. The raw material was dissolved while stirring for about 10 minutes at 150°C in a nitrogen atmosphere. As the first step of the reaction, the temperature was raised to 220° C. over 30 minutes, and the reaction was carried out at atmospheric pressure for 60 minutes. Then, the pressure was reduced from normal pressure to 13.3 kPa over 90 minutes and maintained at 13.3 kPa for 30 minutes to remove the generated phenol out of the reaction system. Subsequently, as a step of the second stage of the reaction, the pressure was reduced to 0.10 kPa or less over 15 minutes while the temperature of the heat medium was raised to 240° C. over 15 minutes, and the generated phenol was taken out of the reaction system. After reaching a predetermined stirring torque, the reaction was stopped by returning the pressure to normal pressure with nitrogen, and the resulting polyester carbonate was extruded in water to cut the strands to obtain polycarbonate resin pellets.

(Production of retardation film)

Retardation film (thickness: 57 μm, photoelastic coefficient: 16 × 10 ^-12 Pa, Re (450): 120 nm, Re (550): 140 nm, Re (450) / Re(550): 0.86) was obtained. In that case, the extending|stretching direction was made into 45 degrees with respect to the longitudinal direction of a film. In addition, the draw ratio was adjusted to 2-3 times so that the retardation film obtained might express the retardation of (lambda)/4. In addition, the extending|stretching temperature was 148 degreeC (namely, Tg+5 degreeC of unstretched modified polycarbonate film).

3. Formation of an easily adhesive layer

8 parts by weight of a modified polyolefin resin (manufactured by Unitica, trade name 'Arrow Base SE-1030N') and a polyvinyl alcohol-based resin such that the mass ratio of the polyolefin-based component and the polyvinyl alcohol-based component is 98:2 (The Nippon Kosei Chemical Industry Co., Ltd. make, brand name 'Kose-Faimer Z200') was mixed with 0.9 weight part of aqueous solution and 27.0 weight part of pure waters, and the easily adhesive composition was obtained.

Using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, trade name 'RSA-G2'), the load mode was set to the tensile mode, the temperature increase rate was 10°C/min, the frequency was 1 Hz, and the obtained easy-adhesive composition was stored at 0.1% initial strain. The elastic modulus was measured. The storage elastic modulus in 85 degreeC of the obtained easily adhesive agent composition was 2.4x10 ⁶ Pa. Moreover, the storage elastic modulus in 85 degreeC of the easily adhesive agent composition after heating on conditions of 80 degreeC and 500 hours in crosslinking agent presence was 6.7x10 ⁶ Pa.

The obtained easily adhesive composition was apply|coated on one side of retardation film with a bar coater (#6) so that the thickness after drying might be set to 500 nm. Thereafter, an easily adhesive layer (thickness 500 nm) was formed on one side of the retardation film by putting the polycarbonate-based resin film in a hot air dryer (90° C.) and drying the easily adhesive composition for about 5 minutes.

4. Fabrication of polarizing plate

The polarizer was bonded to the easily-adhesive layer-forming surface of the retardation film via a water-soluble adhesive having a polyvinyl alcohol-based resin as a main component (manufactured by Nippon Kosei Chemical Industry Co., Ltd., trade name 'Kosefaimer Z200'). In addition, the polarizer and the retardation film were pasted together so that the angle which the absorption axis of a polarizer and the slow axis of retardation film make may be set to 45 degrees. Next, on the surface opposite to the retardation layer of the polarizer, a TAC film (manufactured by Dainippon Printing, trade name 'DSG-03', thickness 70 µm) as a protective film is applied to a water-soluble adhesive (Nippon Kosei Chemical) containing a polyvinyl alcohol-based resin as a main component. The polarizing plate was obtained by bonding together through the industrial company make, brand name "Kosefimer Z200").

<Example 2>

A polarizing plate was prepared in the same manner as in Example 1, except that an easily adhesive composition was obtained by mixing the modified polyolefin resin, the polyvinyl alcohol-based resin, and pure water so that the mass ratio of the polyolefin-based component and the polyvinyl alcohol-based component was 90:10. . Moreover, the storage elastic modulus in 85 degreeC of the obtained easily adhesive agent composition was 6.4x10 ⁶ Pa. Moreover, the storage elastic modulus in 85 degreeC of the easily adhesive composition after heating on conditions of 80 degreeC and 500 hours in crosslinking agent presence was 8.2x10 ⁶ Pa.

<Comparative Example 1>

In the same manner as in Example 1, except that an easily adhesive composition was obtained by mixing a modified polyolefin resin and pure water without using a polyvinyl alcohol-based resin so that the mass ratio of the polyolefin-based component and the polyvinyl alcohol-based component was 10:0. Thus, a polarizing plate was manufactured. Moreover, the storage elastic modulus in 85 degreeC of the obtained easily adhesive agent composition was 8.8x10 ⁵ Pa. Moreover, the storage elastic modulus in 85 degreeC of the easily adhesive composition after heating under the conditions of 80 degreeC and 500 hours in crosslinking agent presence was 8.9x10 ⁵ Pa.

<Comparative Example 2>

A polarizing plate was prepared in the same manner as in Example 1, except that an easily adhesive composition was obtained by mixing the modified polyolefin resin, the polyvinyl alcohol-based resin, and pure water so that the mass ratio of the polyolefin-based component and the polyvinyl alcohol-based component was 85:15. did Moreover, the storage elastic modulus in 85 degreeC of the obtained easily adhesive agent composition was 1.6x10 ⁷ Pa. Moreover, the storage elastic modulus in 85 degreeC of the easily adhesive composition after heating under the conditions of 80 degreeC and 500 hours in crosslinking agent presence was 8.2x10< ⁸ >Pa.

<Comparative Example 3>

A polarizing plate was prepared in the same manner as in Example 1, except that an easily adhesive composition was obtained by mixing the modified polyolefin resin, polyvinyl alcohol-based resin, and pure water so that the mass ratio of the polyolefin-based component and the polyvinyl alcohol-based component was 70:30. did Moreover, the storage elastic modulus in 85 degreeC of the obtained easily adhesive agent composition was 4.5x10 ⁷ Pa. Moreover, the storage elastic modulus in 85 degreeC of the easily adhesive composition after heating under the conditions of 80 degreeC and 500 hours in crosslinking agent presence was 8.8x10< ⁸ >Pa.

<Comparative Example 4>

In the same manner as in Example 1, except that an easily adhesive composition was obtained by mixing a polyvinyl alcohol-based resin and pure water without using a modified polyolefin resin, so that the mass ratio of the polyolefin-based component and the polyvinyl alcohol-based component was 0:10. Thus, a polarizing plate was manufactured. In addition, the storage elastic modulus in 85 degreeC of the obtained easily adhesive agent composition was 2.3x10< ⁸ >Pa. Moreover, the storage elastic modulus in 85 degreeC of the easily adhesive composition after heating on conditions of 80 degreeC and 500 hours in crosslinking agent presence was 9.5x10< ⁹ >Pa.

<Comparative Example 5>

10 parts by weight of a water-based urethane resin (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., trade name 'Superflex 210') and 1.8 parts by weight of an oxazoline-based crosslinking agent (manufactured by Nippon Shokubai Co., Ltd., trade name 'Epocross WS700') A polarizing plate was prepared in the same manner as in Example 1 except that 83 parts by weight of pure water was mixed and an easily adhesive composition was obtained. The storage elastic modulus in 85 degreeC of the obtained easily adhesive agent composition was 2.0x10< ⁸ >Pa. Moreover, the storage elastic modulus in 85 degreeC of the easily adhesive agent composition after heating on 80 degreeC and the conditions of 500 hours was 4.1x10< ⁸ >Pa.

(evaluation)

The following evaluation was performed about the said Example and the comparative example. An evaluation result is shown in Table 1.

(1) Initial adhesion test

The adhesive was apply|coated to the retardation layer side of the polarizing plate obtained by the said Example and the comparative example, and it bonded together to the glass substrate, and the sample for a measurement was produced. Insert a cut with a cutter knife between the polarizer of this measurement sample and the easily adhesive layer, and set the polarizer and the protective film at an angle of 90° with respect to the surface of the retardation layer, and the force required for peeling at a peeling rate of 3000 mm/min. (Peeling force: N/15 mm) was measured using an angle freedom type adhesion/film peeling analyzer (manufactured by Kyowa Interface Chemical Co., Ltd., trade name 'VPA-2'). In addition, in order to be put to practical use as a polarizing plate, the peeling force needs to be 1N/15mm or more.

(2) Peeling of polarizer after humidification test

After humidifying the polarizing plates obtained in Examples and Comparative Examples at 60° C. and 95% RH for 500 hours, the presence or absence of peeling of the polarizer was observed using an optical microscope.

(3) Crack of polarizer after heat shock test

After repeating 300 times of maintaining the polarizing plates obtained in Examples and Comparative Examples for 30 minutes in a temperature environment of -40°C and 85°C, respectively, the presence or absence of cracks in the polarizer was observed using an optical microscope.

(4) Peeling of polarizer after heating test

After heating the polarizing plates obtained in Examples and Comparative Examples at 80° C. for 500 hours, the presence or absence of peeling of the polarizer was observed using an optical microscope.

[Table 1]

[Industrial Applicability]

The polarizing plate of this invention is used suitably for an image display apparatus, for example. Specifically, it is suitable as a liquid crystal panel for liquid crystal TVs, liquid crystal displays, mobile phones, digital cameras, video cameras, portable game machines, car navigation systems, copiers, printers, fax machines, watches, microwaves, etc., as well as anti-reflection plates for organic EL devices. is used sparingly

1: Polarizer
2: easily adhesive layer
3: Retardation layer (resin layer)
10: polarizer

Claims (10)

It has a resin layer and a polarizer,
The resin layer and the polarizer are laminated with an easily adhesive layer interposed therebetween,
The resin layer is a retardation layer having an in-plane retardation, which is composed of a polycarbonate-based resin film,
The in-plane retardation Re (550) of the retardation layer is 100 nm to 180 nm, and also satisfies the relationship of Re (450) < Re (550),
The storage elastic modulus at 85° C. of the easily adhesive layer is 1.0×10 ⁶ Pa to 1.0×10 ⁷ Pa,
Polarizer:
Here, Re(450) and Re(550) represent the in-plane retardation measured with the light of wavelength 450nm and 550nm in 23 degreeC, respectively. According to claim 1,
The easily adhesive layer is a polarizing plate having a storage elastic modulus of 1.0×10 ⁶ Pa to 1.0×10 ⁷ Pa at 85° C. after heating at 80° C. under the conditions of 500 hours in the presence of a crosslinking agent. 3. The method of claim 1 or 2,
A polarizing plate wherein the easily adhesive layer includes a polyolefin-based component and a polyvinyl alcohol-based component. 4. The method of claim 3,
A polarizing plate having a mass ratio of the polyolefin-based component to the polyvinyl alcohol-based component of 98:2 to 90:10. According to claim 1,
A polarizing plate having a thickness of 500 nm to 1 μm of the easily adhesive layer. According to claim 1,
The polarizing plate by which the said easily adhesive layer and the said polarizer are bonded through the adhesive agent containing a polyvinyl alcohol-type resin. delete delete According to claim 1,
An angle between the absorption axis of the polarizer and the slow axis of the retardation layer is 38° to 52°.

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