KR20210071999A - Polarizing plate with retardation layer and image display device using same - Google Patents

Abstract

The present invention provides a polarizing plate with a retardation layer that is thin, has excellent handleability, and has excellent optical properties. A polarizing plate with a retardation layer of the present invention includes a polarizing film and a polarizing plate including a protective layer on at least one side of the polarizing film, and a retardation layer. The polarizing film is composed of a polyvinyl alcohol-based resin film containing a dichroic substance, and the thickness thereof is 8 μm or less, and the orthogonal absorbance per 1 μm in thickness at a wavelength of 210 nm is 1.00 or less. Re(550) of the retardation layer is 100 nm to 190 nm, and Re(450)/Re(550) is 0.8 or more and less than 1. The angle between the slow axis of the retardation layer and the absorption axis of the polarizing film is 40° to 50°.

Description

Polarizing plate with retardation layer and image display device using same

The present invention relates to a polarizing plate with a retardation layer and an image display device using the same.

BACKGROUND ART In recent years, an image display device typified by a liquid crystal display device and an electroluminescent (EL) display device (eg, an organic EL display device, an inorganic EL display device) has spread rapidly. A polarizing plate and a retardation plate are typically used for an image display apparatus. Practically, a polarizing plate with a retardation layer in which a polarizing plate and a retardation plate are integrated is widely used (for example, Patent Document 1). this is getting stronger Moreover, in recent years, the demand for a curved image display device and/or a bendable or bendable image display device is increasing, and further thinning and further softening of the thickness of the polarizing plate and the polarizing plate with a retardation layer are required. For the purpose of reducing the thickness of a polarizing plate with a retardation layer, a protective layer of a polarizing film having a large contribution to the thickness and a thickness reduction of the retardation film are progressing. However, when a protective layer and retardation film are made thin, the influence of the shrinkage|contraction of a polarizing film becomes relatively large, and the problem of the curvature of an image display apparatus and fall of the operability of a polarizing plate with a retardation layer arises.

In order to solve the above problems, it is necessary to reduce the thickness of the polarizing film as well. However, if the thickness of the polarizing film is only made thin, the optical properties will be deteriorated. More specifically, one or both of the polarization degree and the single transmittance, which are in a trade-off relationship, decrease to a practically unacceptable level. As a result, the optical properties of the polarizing plate with a retardation layer also become insufficient.

Japanese Patent Publication No. 3325560

The present invention has been made in order to solve the above conventional problems, and its main object is to provide a polarizing plate with a retardation layer which is thin, has excellent handleability, and has excellent optical properties.

A polarizing plate with a retardation layer of the present invention includes a polarizing film, a polarizing plate including a protective layer on at least one side of the polarizing film, and a retardation layer. The polarizing film is composed of a polyvinyl alcohol-based resin film containing a dichroic substance, has a thickness of 8 µm or less, and has an orthogonal absorbance of 1.00 or less per 1 µm in thickness at a wavelength of 210 nm. Re(550) of the retardation layer is 100nm to 190nm, Re(450)/Re(550) is 0.8 or more and less than 1, and the angle between the slow axis of the retardation layer and the absorption axis of the polarizing film is 40° to 50 is °.

In one embodiment, the said protective layer is comprised from the base material whose elasticity modulus is 3000 MPa or more.

In one embodiment, the total thickness of the said polarizing plate with a retardation layer is 90 micrometers or less, a front reflection hue is 3.5 or less, and the said protective layer is comprised from the resin film whose elasticity modulus is 3000 MPa or more.

In one embodiment, the protective layer is composed of a triacetyl cellulose-based resin film.

In one embodiment, the said polarizing plate contains the said polarizing film and the said protective layer arrange|positioned only on one side of the said polarizing film, and the said retardation layer is bonded to the said polarizing film via an adhesive layer.

In one embodiment, the said retardation layer is comprised from a polycarbonate-type resin film.

In one embodiment, the retardation layer is composed of a polycarbonate-based resin film having a thickness of 40 µm or less.

In one embodiment, the ratio (A ₄₇₀ /A _{600 ) of the orthogonal absorbance (A 470} ) at a wavelength of 470 nm to the orthogonal absorbance (A ₆₀₀ ) at a wavelength of 600 nm of the polarizing film is 0.7 to 2.00.

In one embodiment, the orthogonal b value of the polarizing film is greater than -10 and less than or equal to +10.

In one embodiment, the iodine concentration of the polarizing film is 3.0% by weight or more.

In one embodiment, the single transmittance|permeability of the said polarizing film is 42.5% or more.

In one embodiment, the polarizing plate with a retardation layer further includes another retardation layer outside the retardation layer, and the refractive index characteristic of the other retardation layer shows a relationship of nz>nx=ny.

In one embodiment, the said polarizing plate with a retardation layer further contains the isotropic base material with a conductive layer or a conductive layer on the outer side of the said retardation layer.

In one embodiment, the polarizing plate with a retardation layer has a long picture shape, the polarizing film has an absorption axis in a long direction, and the retardation layer has a slow axis in a direction forming an angle of 40° to 50° with respect to the long direction. to be. In one embodiment, the said polarizing plate with retardation layer is wound in roll shape.

According to another aspect of the present invention, an image display apparatus is provided. This image display apparatus is equipped with said polarizing plate with a retardation layer.

In one embodiment, the said image display apparatus is an organic electroluminescent display apparatus or an inorganic electroluminescent display apparatus.

According to the present invention, a combination of halide (typically potassium iodide) addition to a polyvinyl alcohol (PVA)-based resin, two-stage stretching including aerial assisted stretching and underwater stretching, and drying and shrinkage by heating rolls are combined. By employing the polarizing film as a thin film, it is possible to obtain a polarizing film having extremely excellent optical properties. By using such a polarizing film, it is thin and is excellent in handleability, and the polarizing plate with a retardation layer excellent in optical characteristics can be implement|achieved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the polarizing plate with retardation layer which concerns on one Embodiment of this invention.
2 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another embodiment of the present invention.
3 : is schematic which shows an example of the drying shrinkage process using the heating roll in the manufacturing method of the polarizing film used for the polarizing plate with retardation layer of this 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 the present 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 maximized (ie, the slow axis direction), 'ny' is the refractive index in the direction orthogonal to the slow axis in the plane (ie, the fast axis direction), and 'nz' is It is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

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

(3) retardation in thickness direction (Rth)

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

(4) Nz coefficient

The Nz coefficient can be calculated|required by Nz=Rth/Re.

(5) angle

When referring to an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Thus, for example, '45°' means ±45°.

A. Overall configuration of polarizing plate with retardation layer

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the polarizing plate with retardation layer which concerns on one Embodiment of this invention. The polarizing plate 100 with a retardation layer of this embodiment contains the polarizing plate 10 and the retardation layer 20. As shown in FIG. The polarizing plate 10 includes a polarizing film 11 , a first protective layer 12 disposed on one side of the polarizing film 11 , and a second protective layer 13 disposed on the other side of the polarizing film 11 . ) is included. Depending on the purpose, one of the first protective layer 12 and the second protective layer 13 may be omitted. For example, when the retardation layer 20 can also function as a protective layer of the polarizing film 11, the second protective layer 13 may be omitted. In the embodiment of the present invention, the polarizing film is composed of a polyvinyl alcohol-based resin film containing a dichroic substance. The thickness of the polarizing film is 8 μm or less, and the orthogonal absorbance per 1 μm in thickness at a wavelength of 210 nm (hereinafter referred to as unit absorbance) is 1.00 or less.

As shown in FIG. 2 , in the polarizing plate 101 with a retardation layer according to another embodiment, another retardation layer 50 and/or an isotropic substrate 60 with a conductive layer or a conductive layer may be provided. The other retardation layer 50 and the conductive layer or the isotropic substrate 60 with a conductive layer are typically provided outside the retardation layer 20 (opposite to the polarizing plate 10). The other retardation layers typically exhibit the relationship of refractive index characteristics of nz>nx=ny. The other retardation layer 50 and the conductive layer or the isotropic substrate 60 with a conductive layer are typically provided in this order from the retardation layer 20 side. The other retardation layer 50 and the conductive layer or the isotropic base material 60 with a conductive layer are arbitrary layers typically provided as needed, and either one or both may be abbreviate|omitted. In addition, for convenience, the retardation layer 20 is referred to as a first retardation layer, and the other retardation layer 50 is referred to as a second retardation layer in some cases. In addition, when a conductive layer or an isotropic substrate with a conductive layer is provided, the polarizing plate with a retardation layer has a built-in touch sensor between the image display cell (eg, organic EL cell) and the polarizing plate, so-called inner touch panel type input display can be applied to the device.

In the embodiment of the present invention, Re(550) of the first retardation layer 20 is 100 nm to 190 nm, and Re(450)/Re(550) is 0.8 or more and less than 1. In addition, the angle between the slow axis of the first retardation layer 20 and the absorption axis of the polarizing film 11 is 40° to 50°.

The above embodiments may be appropriately combined, and modifications apparent in the art may be added to the constituent elements of the above embodiments. For example, even if the configuration in which the isotropic substrate 60 with a conductive layer is provided outside the second phase difference layer 50 is replaced with an optically equivalent configuration (eg, a laminate of the second phase difference layer and the conductive layer) do.

The polarizing plate with a retardation layer which concerns on embodiment of this invention may further contain the other retardation layer. Other optical characteristics (eg, refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, and the like of the retardation layer may be appropriately set according to the purpose.

The polarizing plate with retardation layer of this invention may be single-leaf shape, or long picture shape may be sufficient as it. As used herein, the term 'long shape' means an elongate shape having a sufficiently long length with respect to the width, and includes, for example, an elongated shape with a length of 10 times or more, preferably 20 times or more with respect to the width. The elongate polarizing plate with retardation layer can be wound in roll shape. When the polarizing plate with retardation layer is elongate shape, a polarizing plate and retardation layer are also elongate shape. In this case, the polarizing film preferably has an absorption axis in the long direction. The first retardation layer is preferably an obliquely stretched film having a slow axis in a direction forming an angle of 40° to 50° with respect to the long direction. If a polarizing film and a 1st retardation layer are such a structure, a polarizing plate with a retardation layer can be produced with a roll-to-roll.

Practically, an adhesive layer (not shown) is provided on the opposite side to the polarizing plate of the retardation layer, and the polarizing plate with a retardation layer can be affixed to an image display cell. Moreover, it is preferable that the peeling film is temporarily attached to the surface of an adhesive layer until the polarizing plate with retardation layer is provided for use. By temporarily adhering a peeling film, while protecting an adhesive layer, roll formation is attained.

The front reflection hue (√(a ^*2 +b ^*2 )) of the polarizing plate with a retardation layer becomes like this. Preferably it is 3.5 or less, More preferably, it is 3.0 or less. As a result of suppressing undesired coloring etc. as a front reflection hue is in the said range, the polarizing plate with retardation layer excellent in reflection characteristics can be obtained.

The total thickness of the polarizing plate with a retardation layer is preferably 140 µm or less, more preferably 120 µm or less, still more preferably 100 µm or less, still more preferably 90 µm or less, still more preferably 85 µm or less. The lower limit of the total thickness may be, for example, 30 μm. According to the embodiment of the present invention, an extremely thin polarizing plate with a retardation layer can be realized in this way. Such a polarizing plate with a retardation layer may have extremely excellent flexibility and bending durability. Such a polarizing plate with a retardation layer can be especially suitably applied to a curved image display apparatus and/or a bendable or bendable image display apparatus. In addition, the total thickness of the polarizing plate with a retardation layer means the sum of the thicknesses of all the layers constituting the polarizing plate with a retardation layer, except for the pressure-sensitive adhesive layer for making the polarizing plate with a retardation layer in close contact with an external adherend such as a panel or glass ( That is, the total thickness of the polarizing plate with a retardation layer does not include a pressure-sensitive adhesive layer for affixing the polarizing plate with a retardation layer to an adjacent member such as an image display cell and the thickness of a release film that can be temporarily attached to the surface thereof).

Hereinafter, the components of a polarizing plate with a retardation layer are demonstrated in detail.

B. Polarizer

B-1. Polarizing film

As described above, the polarizing film 11 has a thickness of 8 μm or less, and a unit absorbance of 1.00 or less at a wavelength of 210 nm. The polarizing film used in the present invention has a very small unit absorbance at a wavelength of 210 nm as compared to a typical thin polarizing film. This means that the content ratio of uncomplexed iodine ions (having absorption in the ultraviolet region around 210 nm) with PVA in the polarizing film is very small. In the polarizing film, iodine can be roughly divided into an iodine ion having absorption in the ultraviolet region and a PVA-iodine complex having absorption in visible light. Among them, it is the PVA-iodine complex that contributes to the polarization properties of the polarizing film. Since the amount of iodine that can be contained in the polarizing film is finite, a decrease in iodine ions leads to an increase in the PVA-iodine complex. That is, it becomes possible to improve optical properties by reducing iodine ions in a thin polarizing film having a thickness of 8 µm or less. This tendency becomes remarkable especially in the polarizing film which is thin and the iodine concentration in a film|membrane becomes high. The unit absorbance at a wavelength of 210 nm is preferably 0.80 or less, and more preferably 0.60 or less. The lower limit of the unit absorbance at a wavelength of 210 nm may be, for example, 0.20. Absorbance units can be calculated by dividing the orthogonal absorbance A _210, which is available by the following on the basis of the perpendicular transmittance Tc of the polarizing plate to be measured when the obtained degree of polarization to be described later expression in thickness. In addition, the unit absorbance of the polarizing plate substantially corresponds to the unit absorbance of the polarizing film.

Orthogonal absorbance=log10(100/Tc)

It is one of the characteristics of the present invention to use a thin polarizing film having such characteristics. In addition, in relation to the polarizing film having the unit absorbance as described above, the ratio of the orthogonal absorbance (A ₅₅₀ ) at a wavelength of 550 nm to the orthogonal absorbance (A ₂₁₀ ) at a wavelength of 210 nm (A ₅₅₀ /A ₂₁₀ ) is preferably 1.4 It is more than, More preferably, it is 1.8 or more, More preferably, it is 2.0 or more, Especially preferably, it is 2.2 or more. The upper limit of the ratio (A ₅₅₀ /A ₂₁₀ ) may be, for example, 3.5. This means that the content ratio of iodine ions in the polarizing film decreased and the content ratio of the PVA-I ₅ ⁻ complex having absorption near 600 nm increased.

The thickness of the polarizing film is preferably 1 µm to 8 µm, more preferably 1 µm to 7 µm, still more preferably 2 µm to 5 µm, particularly preferably 2 µm to 4 µm, especially preferably Preferably, it is 2 μm to 3 μm.

The polarizing film preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizing film is preferably 49.0% or less, and more preferably 48.0% or less. On the other hand, the single transmittance is preferably 41.5% or more, more preferably 42.0% or more, still more preferably 42.5% or more. The polarization degree of the polarizing film is preferably 99.990% or more, and preferably 99.998% or less. The single transmittance is typically measured using an ultraviolet/visible light spectrophotometer, and is a Y value obtained by correcting visibility. The polarization degree can be obtained by the following formula, based on the parallel transmittance (Tp) and the orthogonal transmittance (Tc), which are typically measured using an ultraviolet/visible light spectrophotometer and corrected for visibility.

Polarization degree (%)={(Tp-Tc)/(Tp+Tc)} ^1/2 × 100

In one embodiment, the transmittance of a thin polarizing film of 8 µm or less is typically measured by using a laminate of a polarizing film (refractive index of surface: 1.53) and a protective film (refractive index: 1.50) as a measurement target, and ultraviolet/visible light It is measured using a spectrophotometer. Depending on the refractive index of the surface of the polarizing film and/or the refractive index of the surface in contact with the air interface of the protective film, the reflectance at the interface of each layer changes, and as a result, the measured value of the transmittance may change. Therefore, for example, when a protective film having a refractive index other than 1.50 is used, the measured value of transmittance may be corrected according to the refractive index of the surface of the protective film in contact with the air interface. Specifically, the correction value C of the transmittance is expressed by the following formula using the reflectance _{R 1} (transmission axis reflectance) of polarized light parallel to the transmission axis at the interface between the protective film and the air layer.

C=R ₁ -R ₀

R ₀ =((1.50-1) ² /(1.50+1) ² )×(T ₁ /100)

R ₁ =((n ₁ -1) ² /(n ₁ +1) ² )×(T ₁ /100)

Here, R ₀ is the transmittance reflectance when the protective film having a refractive index of 1.50 _{is used, n 1} is the refractive index of the protective film to be used, and T ₁ is the transmittance of the polarizing film. For example, when a substrate having a surface refractive index of 1.53 (a cycloolefin-based film, a film with a hard coat layer, etc.) is used as the protective film, the correction amount (C) is about 0.2%. In this case, by adding 0.2% to the transmittance obtained by the measurement, it is possible to convert the polarizing film having a surface refractive index of 1.53 to the transmittance in the case of using a protective film having a refractive index of 1.50. In addition, according to the calculation based on the above formula, _{the amount of change in the correction value (C) when the transmittance (T 1} ) of the polarizing film is changed by 2% is 0.03% or less, and the transmittance of the polarizing film affects the value of the correction value (C) The impact is limited. In addition, when the protective film has absorption other than surface reflection, appropriate correction can be performed according to the amount of absorption.

Preferably, the polarizing film has a ratio (A ₄₇₀ /A _{600 ) of the orthogonal absorbance (A 470} ) at a wavelength of 470 nm to the orthogonal absorbance (A ₆₀₀ ) at a wavelength of 600 nm is 0.7 or more, more preferably 0.75 or more, and further Preferably it is 0.80 or more, Especially preferably, it is 0.85 or more. Ratio ( _A470 / _A600 ) becomes like this. Preferably it is 2.00 or less, More preferably, it is 1.33 or less. If the ratio (A ₄₇₀ /A _{600 ) is within such a range, the content ratio of the PVA-I 3} ^- complex having absorption in the vicinity of 480 nm can be maintained without significantly reducing it. As a result, good polarization performance can be realized over the entire visible light range. While the amount of iodine in the thin polarizing film is limited _{, it was difficult to set both the above unit absorbance and the ratio (A 470} /A ₆₀₀ ) in a desired range with the prior art, but the polarizing film used in the present invention has these Both can be made into a desired range.

The orthogonal b value of the polarizing film is, for example, greater than -10, preferably -7 or more, and more preferably -5 or more. The orthogonal b value is preferably +10 or less, more preferably +5 or less. The orthogonal b value represents the color when the polarizing film (finally, a polarizing plate with a retardation layer) is arranged in an orthogonal state, and the larger the absolute value of this value, the more the orthogonal color (black display in the image display device) is colored. means to be seen For example, when the orthogonal b value is as low as -10 or less, the black display looks blue, and the display performance deteriorates. That is, according to the embodiment of the present invention, it is possible to obtain a polarizing plate with a retardation layer capable of realizing an excellent color in black display. In addition, the orthogonal b value can be measured by a spectrophotometer represented by V-7100.

The iodine concentration of the polarizing film is preferably 3% by weight or more, more preferably 4% by weight or more, and still more preferably 6% by weight or more. The upper limit of the iodine concentration may be, for example, 12% by weight. When the iodine concentration is within such a range, the effect by reducing the unit absorbance is remarkable. In other words, the above effect is remarkable in the thin polarizing film in which the iodine concentration becomes high in this way.

Any suitable polarizing film may be employed as the polarizing film. The polarizing film may be typically manufactured using a laminate of two or more layers.

As a specific example of the polarizing film obtained using a laminated body, the polarizing film obtained using the laminated body of the resin base material and the PVA-type resin layer apply|coated to the said resin base material is mentioned. A polarizing film obtained 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, drying it, and forming a PVA-based resin layer on the resin substrate to form a resin obtaining a laminate of a base material and a PVA-based resin layer; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizing film; In this embodiment, extending|stretching typically includes extending|stretching by immersing a laminated body in boric-acid aqueous solution. In addition, the stretching may further include aerial stretching of 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 / polarizing film may be used as it is (that is, the resin substrate may be used as a protective layer of the polarizing film), or the resin substrate is peeled from the laminate of the resin substrate / polarizing film, Any suitable protective layer may be laminated and used. Details of the method for manufacturing such a polarizing film are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. This publication is incorporated herein by reference in its entirety.

The manufacturing method of a polarizing film typically forms a polyvinyl alcohol-type resin layer containing a halide and a polyvinyl alcohol-type resin on one side of a long thermoplastic resin base material to make a laminate, and aerial auxiliary stretching treatment on the laminate. and dyeing treatment, underwater stretching treatment, and drying shrinkage treatment of shrinking 2% or more in the width direction by heating while conveying in the longitudinal direction in this order. Accordingly, a polarizing film having a thickness of 8 μm or less and a unit absorbance of 1.00 or less at a wavelength of 210 nm and having excellent optical properties can be provided. That is, by introducing auxiliary stretching, even when PVA is applied on a thermoplastic resin, it becomes possible to increase the crystallinity of PVA, and it becomes possible to achieve high optical properties. In addition, by increasing the orientation of PVA in advance at the same time, it is possible to prevent problems such as a decrease in orientation and dissolution of PVA when immersed in water in a subsequent dyeing process or stretching process, and it is possible to achieve high optical properties do. In addition, in the case where the PVA-based resin layer is immersed in a liquid, as compared to the case in which the PVA-based resin layer does not contain a halide, disorder in the orientation of polyvinyl alcohol molecules and a decrease in orientation can be suppressed. Thereby, the optical characteristic of the polarizing film obtained through the processing process performed by immersing a laminated body in a liquid, such as a dyeing process and an underwater extending|stretching process, can be improved. Moreover, an optical characteristic can be improved by shrinking|contracting a laminated body in the width direction by dry shrinkage process.

B-2. protective layer

The first protective layer 12 and the second protective layer 13 are each formed of any suitable film usable as a protective layer of the polarizing film. 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 transparent resins such as polysulfone-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based and acetate-based resins. Moreover, thermosetting resins, such as (meth)acrylic type, a urethane type, a (meth)acrylic urethane type, an epoxy type, a silicone type, or ultraviolet curable resin, etc. are mentioned. In addition to this, for example, a glassy polymer such as a siloxane-based polymer may also be mentioned. Moreover, the polymer film described in Unexamined-Japanese-Patent No. 2001-343529 (WO01/37007) can also be used. As a material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in a 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. In one embodiment, the protective layer (particularly, the protective layer on the visual side) contains TAC-type resin. By using the TAC-based resin film as the protective layer, bending durability can be improved.

The polarizing plate with a retardation layer of this invention is typically arrange|positioned on the visual recognition side of an image display apparatus so that it may mention later, and the 1st protective layer 12 is typically arrange|positioned at the visual recognition side. Accordingly, the first protective layer 12 may be subjected to a surface treatment such as a hard coat treatment, an antireflection treatment, an antistick treatment, or an antiglare treatment, if necessary. In addition/or, treatment for improving visibility when visually recognized through polarized sunglasses (typically, imparting a (other) circular polarization function, imparting a super-high phase difference) to the first protective layer 12 if necessary may be performed. By performing such a process, excellent visibility can be implement|achieved even when a display screen is visually recognized through polarizing lenses, such as polarized sunglasses. Therefore, the polarizing plate with a retardation layer can be suitably applied also to the image display apparatus which can be used outdoors.

The thickness of the first protective layer is preferably 5 µm to 80 µm, more preferably 10 µm to 40 µm, still more preferably 10 µm to 35 µm. In addition, when surface treatment is performed, the thickness of an outer side protective layer is the thickness including the thickness of a surface treatment layer.

It is preferable that the 2nd protective layer 13 is optically isotropic in one embodiment. 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. The second protective layer 13 may be a retardation layer having any suitable retardation value in one embodiment. In this case, the in-plane retardation Re(550) of the retardation layer is, for example, 110 nm to 150 nm. The thickness of the second protective layer is preferably 5 µm to 80 µm, more preferably 10 µm to 40 µm, still more preferably 10 µm to 30 µm. Preferably, the second protective layer may be omitted from the viewpoint of reducing the thickness and weight.

B-3. Method for manufacturing a polarizing film

The polarizing film is, for example, a laminate by forming a polyvinyl alcohol-based resin layer (PVA-based resin layer) containing a halide and a polyvinyl alcohol-based resin (PVA-based resin) on one side of a long thermoplastic resin substrate, and lamination It can be produced by a method comprising subjecting the sieve to an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment for shrinking 2% or more in the width direction by heating while conveying in the longitudinal direction in this order. have. The content of the halide in the PVA-based resin layer is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin. The drying shrinkage treatment is preferably performed using a heating roll, and the temperature of the heating roll is preferably 60°C to 120°C. The shrinkage ratio in the width direction of the laminate by the drying shrinkage treatment is preferably 2% or more. According to such a manufacturing method, the polarizing film described in the section B-1 above can be obtained. In particular, by producing a laminate including a PVA-based resin layer containing a halide, stretching the laminate in multi-step stretching including air-assisted stretching and underwater stretching, and heating the laminate after stretching with a heating roll, excellent optics A polarizing film having characteristics (typically, single transmittance and unit absorbance at a wavelength of 210 nm) can be obtained.

B-3-1. Fabrication of laminates

Any suitable method can be employed as a method for producing a laminate of the thermoplastic resin substrate and the PVA-based resin layer. Preferably, the PVA-based resin layer is formed on the thermoplastic resin substrate by applying a coating solution containing a halide and a PVA-based resin to the surface of the thermoplastic resin substrate and drying. As described above, the content of the halide in the PVA-based resin layer is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin.

Any suitable method can be employ|adopted as a coating method of a coating liquid. For example, the roll coat method, the spin coat method, the wire bar coat method, the dip coat method, the die coat method, the curtain coat method, the spray coat method, the knife coat method (comma coat method, etc.) etc. are mentioned. The coating/drying temperature of the coating liquid is preferably 50°C or higher.

The thickness of the PVA-based resin layer is preferably 3 µm to 40 µm, more preferably 3 µm to 20 µm.

Before forming the PVA-based resin layer, the thermoplastic resin substrate may be subjected to surface treatment (eg, corona treatment, etc.), or an easily adhesive layer may be formed on the thermoplastic resin substrate. By performing such a process, the adhesiveness of a thermoplastic resin base material and a PVA-type resin layer can be improved.

B-3-1-1. Thermoplastic base material

The thickness of the thermoplastic resin substrate is preferably 20 µm to 300 µm, more preferably 50 µm to 200 µm. If it is less than 20 micrometers, there exists a possibility that formation of a PVA-type resin layer may become difficult. When it exceeds 300 micrometers, while extending|requires a long time for a thermoplastic resin base material to absorb water, for example in the below-mentioned extending|stretching process in water, there exists a possibility that it may require excessive load for extending|stretching.

The thermoplastic resin substrate preferably has a water absorption of 0.2% or more, more preferably 0.3% or more. The thermoplastic resin substrate can be plasticized by absorbing water and causing the water to perform a plasticizer motion. As a result, the stretching stress can be significantly reduced and stretching can be performed at a high magnification. On the other hand, the water absorption of the thermoplastic resin substrate is preferably 3.0% or less, more preferably 1.0% or less. By using such a thermoplastic resin base material, the dimensional stability of a thermoplastic resin base material falls remarkably at the time of manufacture, and the problem, such as the external appearance of the polarizing film obtained deteriorates, can be prevented. Moreover, it can prevent that a base material fracture|ruptures at the time of extending|stretching in water, or a PVA-type resin layer peels from a thermoplastic resin base material. In addition, the water absorption of a thermoplastic resin base material can be adjusted by introduce|transducing a modifier into a constituent material, for example. Water absorption is a value which can be calculated|required according to JISK7209.

The glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 120° C. or less. By using such a thermoplastic resin base material, the stretchability of a laminated body can fully be ensured, suppressing crystallization of a PVA-type resin layer. Moreover, considering plasticization of the thermoplastic resin base material by water and extending|stretching in water favorably, it is 100 degrees C or less, Furthermore, it is more preferable that it is 90 degrees C or less. On the other hand, the glass transition temperature of the thermoplastic resin substrate is preferably 60°C or higher. By using such a thermoplastic resin substrate, when the coating liquid containing the PVA-based resin is applied and dried, problems such as deformation (eg, unevenness, sagging, wrinkles, etc.) of the thermoplastic resin substrate are prevented and good A laminate can be manufactured. Moreover, extending|stretching of a PVA-type resin layer can be performed favorably at suitable temperature (for example, about 60 degreeC). In addition, the glass transition temperature of a thermoplastic resin base material can be adjusted by heating using the crystallization material which introduce|transduces a modifier into a constituent material, for example. A glass transition temperature (Tg) is a value which can be calculated|required according to JISK7121.

Any suitable thermoplastic resin may be employed as the constituent material of the thermoplastic resin substrate. Examples of the thermoplastic resin include ester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins such as norbornene-based resins, olefinic resins such as polypropylene, polyamide-based resins, polycarbonate-based resins, copolymer resins thereof, etc. can be heard Among these, preferred are norbornene-based resins and amorphous polyethylene terephthalate-based resins.

In one embodiment, an amorphous (not crystallized) polyethylene terephthalate-type resin is used preferably. Among them, amorphous (hard-to-crystallize) polyethylene terephthalate-based resin is particularly preferably used. Specific examples of the amorphous polyethylene terephthalate resin include a copolymer further containing isophthalic acid and/or cyclohexanedicarboxylic acid as dicarboxylic acid, and a copolymer further containing cyclohexanedimethanol or diethylene glycol as glycol. can

In a preferred embodiment, the thermoplastic resin substrate is composed of a polyethylene terephthalate-based resin containing an isophthalic acid unit. This is because such a thermoplastic resin substrate is extremely excellent in stretchability and crystallization at the time of stretching can be suppressed. This is considered to be by providing a large bending|flexion to a main chain by introduce|transducing an isophthalic acid unit. The polyethylene terephthalate-based resin contains a terephthalic acid unit and an ethylene glycol unit. Preferably the content rate of an isophthalic acid unit is 0.1 mol% or more with respect to the total of all repeating units, More preferably, it is 1.0 mol% or more. This is because a thermoplastic resin substrate having extremely excellent stretchability can be obtained. On the other hand, the content rate of the isophthalic acid unit is preferably 20 mol% or less, more preferably 10 mol% or less with respect to the total of all repeating units. By setting it to such a content ratio, the degree of crystallinity can be favorably increased in the drying shrinkage process mentioned later.

The thermoplastic resin substrate may be stretched in advance (before forming the PVA-based resin layer). In one embodiment, it is extended|stretched in the transverse direction of an elongate thermoplastic resin base material. The transverse direction is preferably a direction orthogonal to the stretching direction of the laminate to be described later. In addition, in this specification, "orthogonal" also includes the case where it is substantially orthogonal. Here, "substantially orthogonal" includes the case of 90°±5.0°, preferably 90°±3.0°, more preferably 90°±1.0°.

Preferably the extending|stretching temperature of a thermoplastic resin base material is Tg-10 degreeC - Tg+50 degreeC with respect to a glass transition temperature (Tg). The draw ratio of the thermoplastic resin substrate is preferably 1.5 to 3.0 times.

As a method of stretching the thermoplastic resin substrate, any suitable method may be employed. Specifically, fixed-end stretching may be used or free-end stretching may be sufficient. A dry type may be sufficient as an extending|stretching method, and a wet type may be sufficient as it. Extending|stretching of a thermoplastic resin base material may be performed in one step, and may be performed in multiple steps. When carrying out in multiple steps, the above-mentioned draw ratio is the product of the draw ratio of each step.

B-3-1-2. coating liquid

The coating solution contains a halide and a PVA-based resin as described above. The coating solution is typically a solution in which the halide and the PVA-based resin are dissolved in a solvent. Examples of the solvent include water, dimethylsulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. have. These can be used individually or in combination of 2 or more types. Among these, water is preferable. The concentration of the PVA-based resin in the solution is preferably 3 parts by weight to 20 parts by weight based on 100 parts by weight of the solvent. If it is such a resin density|concentration, the uniform coating film closely_contact|adhered to a thermoplastic resin base material can be formed. The content of the halide in the coating liquid is preferably 5 to 20 parts by weight based on 100 parts by weight of the PVA-based resin.

You may mix|blend an additive with a coating liquid. As an additive, a plasticizer, surfactant, etc. are mentioned, for example. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. As surfactant, a nonionic surfactant is mentioned, for example. These can be used for the purpose of further improving the uniformity, dyeability, and stretchability of the obtained PVA-based resin layer.

Any suitable resin may be employed as the PVA-based resin. Examples include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer is obtained by saponifying the ethylene-vinyl acetate copolymer. The degree of saponification of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. Saponification degree can be calculated|required according to JISK6726-1994. By using the PVA-type resin of such a saponification degree, the polarizing film excellent in durability can be obtained. When the degree of saponification is too high, there is a possibility of gelation.

The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average degree of polymerization is usually from 1000 to 10000, preferably from 1200 to 4500, more preferably from 1500 to 4300. In addition, an average degree of polymerization can be calculated|required according to JISK6726-1994.

Any suitable halide may be employed as the halide. Examples include iodide and sodium chloride. Examples of the iodide include potassium iodide, sodium iodide and lithium iodide. Among these, potassium iodide is preferable.

The amount of the halide in the coating liquid is preferably 5 to 20 parts by weight based on 100 parts by weight of the PVA-based resin, and more preferably 10 to 15 parts by weight based on 100 parts by weight of the PVA-based resin. When the amount of the halide with respect to 100 parts by weight of the PVA-based resin exceeds 20 parts by weight, the halide may bleed out and the finally obtained polarizing film may become cloudy.

In general, when the PVA-based resin layer is stretched, the orientation of the polyvinyl alcohol molecules in the PVA-based resin is increased, but when the PVA-based resin layer after stretching is immersed in a liquid containing water, the orientation of the polyvinyl alcohol molecules is disturbed and the orientation is may be lowered. In particular, in the case of stretching a laminate of a thermoplastic resin substrate and a PVA-based resin layer in boric acid water, when stretching the laminate in boric acid water at a relatively high temperature in order to stabilize the stretching of the thermoplastic resin substrate, the orientation degree decreases The trend of For example, in general, stretching of a PVA film alone in boric acid water is performed at 60°C, whereas stretching of a laminate of A-PET (thermoplastic resin substrate) and a PVA-based resin layer is performed at a high temperature of around 70°C. It is carried out at a temperature, and in this case, the orientation of the PVA at the initial stage of stretching may be lowered at a stage before being raised by stretching in water. On the other hand, by producing a laminate of a PVA-based resin layer containing a halide and a thermoplastic resin substrate, and stretching the laminate at a high temperature in air (auxiliary stretching) before stretching the laminate in boric acid water, PVA of the laminate after auxiliary stretching Crystallization of the PVA-based resin in the resin-based layer can be promoted. As a result, in the case where the PVA-based resin layer is immersed in the liquid, the disorder of the orientation of the polyvinyl alcohol molecules and the decrease in the orientation can be suppressed as compared to the case where the PVA-based resin layer does not contain a halide. Thereby, the optical characteristic of the polarizing film obtained through the processing process performed by immersing a laminated body in a liquid, such as a dyeing process and an underwater stretching process, can be improved.

B-3-2. Aerial Auxiliary Stretch Treatment

In particular, in order to obtain high optical properties, a method of two-stage stretching in which dry stretching (auxiliary stretching) and stretching in boric acid water are combined is selected. By introducing auxiliary stretching as in two-stage stretching, it is possible to stretch while suppressing crystallization of the thermoplastic resin substrate, and to solve the problem of a decrease in stretchability due to excessive crystallization of the thermoplastic resin substrate in subsequent stretching in boric acid water, thereby producing a laminate It can extend at a higher magnification. Furthermore, when applying the PVA-based resin on the thermoplastic resin substrate, in order to suppress the influence of the glass transition temperature of the thermoplastic resin substrate, it is necessary to lower the application temperature compared to the case of applying the PVA-based resin on a conventional metal drum. As a result, the crystallization of the PVA-based resin becomes relatively low, which may cause a problem that sufficient optical properties cannot be obtained. On the other hand, by introducing auxiliary stretching, even when the PVA-based resin is applied on the thermoplastic resin, it becomes possible to increase the crystallinity of the PVA-based resin, and it becomes possible to achieve high optical properties. At the same time, by increasing the orientation of the PVA-based resin in advance, problems such as a decrease in the orientation and dissolution of the PVA-based resin when immersed in water in a subsequent dyeing process or stretching process can be prevented, and high optical properties are achieved it becomes possible to do

The stretching method of the aerial assisted stretching may be either fixed-end stretching (eg, stretching using a tenter-type stretching machine) or free-end stretching (eg, uniaxial stretching by passing a laminate between rolls having different circumferential speeds). However, free-end stretching can be actively employed in order to obtain high optical properties. In one embodiment, the aerial stretching process includes a heating roll stretching step of stretching the laminated body by a difference in circumferential speed between heating rolls while conveying the laminate in its longitudinal direction. The aerial stretching process typically includes a zone stretching process and a hot roll stretching process. In addition, the order of a zone extending|stretching process and a heated roll extending process is not limited, A zone extending|stretching process may be performed first, and a hot roll extending|stretching process may be performed first. The zone stretching step may be omitted. In one embodiment, the zone stretching process and the heated roll stretching process are performed in this order. Moreover, in another embodiment, it is extended|stretched by holding|gripping the film edge part in a tenter type stretching machine, and extending the distance between tenters in a flow direction (extension of the distance between tenters becomes a draw ratio). At this time, the distance of the tenter in the width direction (direction perpendicular to the flow direction) is set so as to be arbitrarily close. Preferably, with respect to the draw ratio in the flow direction, it may be set to be close to the free end drawing. In the case of free-end stretching, it is calculated as the shrinkage ratio in the width direction = (1/stretch ratio) ^1/2.

Aerial assisted stretching may be performed in one step or may be performed in multiple steps. When carrying out in multiple steps, the draw ratio is the product of the draw ratios of each step. The stretching direction in the aerial assisted stretching is preferably substantially the same as the stretching direction in the underwater stretching.

The draw ratio in the aerial auxiliary drawing is preferably 2.0 to 3.5 times. Preferably the maximum draw ratio in the case of combining aerial auxiliary drawing and underwater drawing is 5.0 times or more with respect to the original length of a laminated body, More preferably, it is 5.5 times or more, More preferably, it is 6.0 times or more. In the present specification, the term 'maximum draw ratio' refers to a draw ratio just before the laminate is broken, and refers to a value 0.2 lower than that value by separately checking the draw ratio at which the laminate is broken.

The stretching temperature of the aerial auxiliary stretching can be set to any appropriate value depending on the forming material of the thermoplastic resin substrate, the stretching method, and the like. The stretching temperature is preferably at least the glass transition temperature (Tg) of the thermoplastic resin substrate, more preferably at least the glass transition temperature (Tg) of the thermoplastic resin substrate +10°C, particularly preferably at least Tg+15°C. On the other hand, the upper limit of extending|stretching temperature becomes like this. Preferably it is 170 degreeC. By stretching at such a temperature, it is possible to suppress the rapid progress of crystallization of the PVA-based resin, thereby suppressing problems due to the crystallization (eg, hindering the orientation of the PVA-based resin layer by stretching). The crystallization index of the PVA-based resin after air-assisted stretching is preferably 1.3 to 1.8, more preferably 1.4 to 1.7. The crystallization index of the PVA-based resin can be measured by the ATR method using a Fourier transform infrared spectrophotometer. Specifically, the measurement is performed using polarized light as the measurement light, and the crystallization index is calculated according to the following formula using the intensities of ^{1141 cm -1} and 1440 cm ^{-1 of the obtained spectrum.}

Crystallization index=(I _C /I _R )

only,

I _C : The intensity ^{of 1141 cm -1} when measured by incident light

I _R: the intensity of the 1440cm ^-1 as measured by the measurement light incident

to be.

B-3-3. insolubilization treatment

If necessary, insolubilization treatment is performed after the aerial auxiliary stretching treatment and before the underwater stretching treatment or dyeing treatment. The insolubilization treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By giving an insolubilization process, water resistance can be provided to a PVA-type resin layer, and the orientation fall of PVA at the time of being immersed in water can be prevented. The concentration of the aqueous boric acid solution is preferably 1 part by weight to 4 parts by weight based on 100 parts by weight of water. The liquid temperature of the insolubilization bath (boric acid aqueous solution) is preferably 20°C to 50°C.

B-3-4. dyeing treatment

The dyeing treatment is typically performed by dyeing the PVA-based resin layer with a dichroic substance (typically iodine). Specifically, it is carried out by adsorbing iodine to the PVA-based resin layer. As the adsorption method, for example, a method of immersing a PVA-based resin layer (laminate) in a dyeing solution containing iodine, a method of coating the dyeing solution on a PVA-based resin layer, and spraying the dyeing solution onto a PVA-based resin layer method and the like. Preferably, it is the method of immersing a laminated body in a dyeing solution (dyeing bath). It is because iodine can adsorb|suck favorably.

The dyeing solution is preferably an aqueous iodine solution. The blending amount of iodine is preferably 0.05 to 0.5 parts by weight with respect to 100 parts by weight of water. In order to improve the solubility of iodine in water, it is preferable to mix|blend iodide with iodine aqueous solution. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, and the like. Among these, potassium iodide is preferable. The blending amount of the iodide is preferably 0.1 part by weight to 10 parts by weight, more preferably 0.3 part by weight to 5 parts by weight with respect to 100 parts by weight of water. The liquid temperature at the time of the dyeing|dyeing of a dyeing liquid is 20-50 degreeC preferably in order to suppress dissolution of a PVA-type resin. In the case of immersing the PVA-based resin layer in the dyeing solution, the immersion time is preferably 5 seconds to 5 minutes, more preferably 30 seconds to 90 seconds, in order to ensure the transmittance of the PVA-based resin layer.

Dyeing conditions (concentration, liquid temperature, immersion time) can be set so that the single transmittance of the polarizing film finally obtained and the unit absorbance at a wavelength of 210 nm become desired values. As such dyeing conditions, preferably, an aqueous iodine solution is used as the dyeing solution, and the ratio of the content of iodine and potassium iodide in the aqueous iodine solution is 1:5 to 1:20. The ratio of the contents of iodine and potassium iodide in the aqueous iodine solution is preferably 1:5 to 1:10. Accordingly, a polarizing film having the above optical properties can be obtained.

When the dyeing process is continuously performed after the treatment of immersing the laminate in a treatment bath containing boric acid (typically, insolubilization treatment), the boric acid contained in the treatment bath is mixed into the dyeing bath, so that the concentration of boric acid in the dyeing bath decreases over time. changes, and as a result, the dyeability may become unstable. In order to suppress the destabilization of dyeability as described above, the upper limit of the concentration of boric acid in the dyeing bath is preferably adjusted to 4 parts by weight, more preferably 2 parts by weight, based on 100 parts by weight of water. On the other hand, the lower limit of the concentration of boric acid in the dyeing bath is preferably 0.1 parts by weight, more preferably 0.2 parts by weight, and still more preferably 0.5 parts by weight with respect to 100 parts by weight of water. In one embodiment, the dyeing process is performed using the dyeing bath previously mix|blended with boric acid. Thereby, the ratio of the change in the concentration of boric acid when boric acid in the treatment bath is mixed into the dyeing bath can be reduced. The amount of boric acid previously blended in the dyeing bath (that is, the content of boric acid not derived from the treatment bath) is preferably 0.1 parts by weight to 2 parts by weight, more preferably 0.5 parts by weight to 100 parts by weight of water. 1.5 parts by weight.

B-3-5. crosslinking treatment

If necessary, a crosslinking treatment is performed after the dyeing treatment and before the underwater stretching treatment. The crosslinking treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing a crosslinking process, water resistance is provided to a PVA-type resin layer, and the orientation fall of PVA at the time of immersing in high temperature water by subsequent underwater extending|stretching can be prevented. The concentration of the aqueous boric acid solution is preferably 1 part by weight to 5 parts by weight based on 100 parts by weight of water. Moreover, when performing a crosslinking process after the said dyeing process, it is preferable to further mix|blend an iodide. By mix|blending an iodide, the elution of the iodine made to adsorb|suck to the PVA-type resin layer can be suppressed. The blending amount of the iodide is preferably 1 part by weight to 5 parts by weight based on 100 parts by weight of water. Specific examples of the iodide are as described above. The liquid temperature of the crosslinking bath (boric acid aqueous solution) is preferably 20°C to 50°C.

B-3-6. Underwater stretching treatment

The underwater stretching treatment is performed by immersing the laminate in a stretching bath. According to the underwater stretching treatment, stretching can be performed at a temperature lower than the glass transition temperature (typically about 80° C.) of the thermoplastic resin substrate or the PVA-based resin layer, and the PVA-based resin layer is stretched at a high magnification while suppressing its crystallization. can do. As a result, a polarizing film having excellent optical properties can be manufactured.

Any suitable method can be employ|adopted for the extending|stretching method of a laminated body. Specifically, fixed-end stretching may be used or free-end stretching (for example, a method of uniaxial stretching by passing a laminate between rolls having different circumferential speeds) may be employed. Preferably free-end stretching is selected. Extending|stretching of a laminated body may be performed in one step, and may be performed in multiple steps. When carrying out in multiple steps, the draw ratio (maximum draw ratio) of the laminated body mentioned later is the product of the draw ratio of each step.

Stretching in water is preferably performed by immersing the laminate in an aqueous boric acid solution (stretching in boric acid water). By using an aqueous boric acid solution as the stretching bath, it is possible to impart rigidity to the PVA-based resin layer to withstand the tension applied during stretching and water resistance insoluble in water. Specifically, boric acid can be crosslinked by hydrogen bonding with the PVA-based resin by generating a tetrahydroxyboric acid anion in an aqueous solution. As a result, rigidity and water resistance are provided to the PVA-based resin layer, so that it can be stretched favorably, and a polarizing film having excellent optical properties can be manufactured.

The aqueous boric acid solution is preferably obtained by dissolving boric acid and/or a borate salt in water as a solvent. The concentration of boric acid is preferably 1 part by weight to 10 parts by weight, more preferably 2.5 parts by weight to 6 parts by weight, and particularly preferably 3 parts by weight to 5 parts by weight with respect to 100 parts by weight of water. By making boric acid concentration into 1 weight part or more, melt|dissolution of a PVA-type resin layer can be suppressed effectively and a polarizing film of a higher characteristic can be manufactured. In addition to boric acid or borate, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde or the like in a solvent can also be used.

Preferably, iodide is mix|blended with the said stretching bath (boric acid aqueous solution). By mix|blending an iodide, the elution of the iodine made to adsorb|suck to the PVA-type resin layer can be suppressed. Specific examples of the iodide are as described above. The concentration of iodide is preferably 0.05 parts by weight to 15 parts by weight, more preferably 0.5 parts by weight to 8 parts by weight based on 100 parts by weight of water.

The stretching temperature (liquid temperature of the stretching bath) is preferably 40°C to 85°C, more preferably 60°C to 75°C. If it is such a temperature, it can extend|stretch at a high magnification, suppressing melt|dissolution of a PVA-type resin layer. Specifically, as described above, the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 60°C or higher in relation to the formation of the PVA-based resin layer. In this case, when extending|stretching temperature is less than 40 degreeC, even if it considers plasticization of the thermoplastic resin base material by water, there exists a possibility that extending|stretching may not be satisfactory. On the other hand, as the temperature of the stretching bath becomes high, the solubility of the PVA-based resin layer increases, and there is a fear that excellent optical properties cannot be obtained. The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.

The draw ratio by extending|stretching in water becomes like this. Preferably it is 1.5 times or more, More preferably, it is 3.0 times or more. The total draw ratio of the laminate is preferably 5.0 times or more, more preferably 5.5 times or more with respect to the original length of the laminate. By achieving such a high draw ratio, a polarizing film having extremely excellent optical properties can be manufactured. Such a high draw ratio can be achieved by employing an underwater stretching method (boric acid underwater stretching).

B-3-7. dry shrinkage treatment

The drying shrinkage treatment may be performed by zone heating performed by heating the entire zone, or may be performed by heating a conveyance roll (using a so-called heating roll) (heating roll drying method). Preferably, both are used. By drying using a heating roll, the heating curl of a laminated body can be suppressed efficiently, and the polarizing film excellent in an external appearance can be manufactured. Specifically, by drying in a state in which the laminate is poured on a heating roll, the crystallization of the thermoplastic resin substrate can be efficiently promoted to increase the crystallinity, and even at a relatively low drying temperature, the crystallinity of the thermoplastic resin substrate can be favorably increased. can As a result, the rigidity of the thermoplastic resin base material increases and becomes a state that can withstand the shrinkage of the PVA-based resin layer due to drying, and curling is suppressed. Moreover, by using a heating roll, since a laminated body can be dried, maintaining a flat state, generation|occurrence|production of not only curl but wrinkles can be suppressed. At this time, the optical properties can be improved by shrinking the laminate in the width direction by drying shrinkage treatment. It is because the orientation of PVA and a PVA/iodine complex can be improved effectively. The shrinkage ratio in the width direction of the laminate by the drying shrinkage treatment is preferably 1% to 10%, more preferably 2% to 8%, and particularly preferably 4% to 6%. By using a heating roll, it can shrink|contract in the width direction continuously, conveying a laminated body, and high productivity can be implement|achieved.

3 is a schematic diagram showing an example of a drying shrinkage treatment. In the drying shrinkage treatment, the laminate 200 is dried while being conveyed by the conveying rolls R1 to R6 and the guide rolls G1 to G4 heated to a predetermined temperature. In the illustrated example, the conveying rolls R1 to R6 are arranged so as to alternately and continuously heat the surface of the PVA resin layer and the surface of the thermoplastic resin substrate. For example, one surface of the laminate 200 (eg, the surface of the thermoplastic resin substrate) You may arrange|position conveyance rolls R1-R6 so that a bay may be continuously heated.

Drying conditions are controllable by adjusting the heating temperature (temperature of a heating roll) of a conveyance roll, the number of heating rolls, contact time with a heating roll, etc. The temperature of the heating roll is preferably 60°C to 120°C, more preferably 65°C to 100°C, and particularly preferably 70°C to 80°C. The crystallinity degree of a thermoplastic resin can be increased favorably, and while being able to suppress curl favorably, the optical laminated body extremely excellent in durability can be manufactured. In addition, the temperature of a heating roll can be measured with a contact thermometer. Although six conveyance rolls are provided in the example of illustration, if there are several conveyance rolls, there will be no restriction|limiting in particular. 2 to 40 conveyance rolls are provided normally, Preferably 4 to 30 are provided. The contact time (total contact time) between the laminate and the heating roll is preferably 1 second to 300 seconds, more preferably 1 to 20 seconds, and still more preferably 1 to 10 seconds.

The heating roll may be installed in a heating furnace (eg, an oven) or may be installed in a normal production line (under a room temperature environment). Preferably, it is installed in the heating furnace provided with the blowing means. By using together drying by a heating roll and hot air drying, the rapid temperature change between heating rolls can be suppressed and the shrinkage|contraction of the width direction can be controlled easily. The temperature of hot air drying becomes like this. Preferably it is 30 degreeC - 100 degreeC. Further, the hot air drying time is preferably 1 second to 300 seconds. The wind speed of the hot air is preferably about 10 m/s to 30 m/s. In addition, the said wind speed is a wind speed in a heating furnace, and can be measured with a mini vane type digital anemometer.

B-3-8. other processing

Preferably, a washing treatment is performed after the underwater stretching treatment and before the drying shrinkage treatment. The washing treatment is typically performed by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

C. First retardation layer

The first retardation layer 20 may have any suitable optical and/or mechanical properties depending on the purpose. The first retardation layer 20 typically has a slow axis. In one embodiment, the angle θ between the slow axis of the first retardation layer 20 and the absorption axis of the polarizing film 11 is 40° to 50° as described above, and preferably 42° to 48°. °, more preferably about 45 °. If the angle θ is within such a range, a polarizing plate with a retardation layer having very excellent circular polarization characteristics (as a result, very excellent antireflection characteristics) can be obtained by using the first retardation layer as a λ/4 plate as described later. .

The first retardation layer preferably has a refractive index characteristic such that nx>ny≥nz. The first retardation layer is typically provided to impart antireflection properties to the polarizing plate, and may function as a λ/4 plate in one embodiment. In this case, the in-plane retardation Re(550) of the first retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, still more preferably 130 nm to 160 nm. In addition, 'ny=nz' includes not only the case where ny and nz are completely equal, but also the case where 'ny=nz' is substantially equal. Therefore, there may be a case where ny<nz is not impaired in the effect of the present invention.

The Nz coefficient of the first retardation layer 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 with retardation layer is used for an image display apparatus, the very excellent reflection hue can be achieved.

The first phase difference layer may exhibit an inverse dispersion wavelength characteristic in which the phase difference value increases with the wavelength of the measurement light, or a positive wavelength dispersion characteristic in which the phase difference value decreases with the wavelength of the measurement light, and the phase difference value is measured A flat wavelength dispersion characteristic that hardly changes even with the wavelength of light may be exhibited. In one embodiment, the first retardation layer exhibits an inverse dispersion wavelength characteristic. In this case, Re(450)/Re(550) of the retardation layer is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection properties can be realized.

The first retardation layer has an absolute value of the photoelastic coefficient of preferably 2×10 ^-11 m2/N or less, more preferably 2.0×10 ^-13 m2/N to 1.5×10 ^-11 m2/N, still more preferably contains 1.0×10 ^-12 m2/N to 1.2×10 ^-11 m2/N 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 at the time of heating occurs. As a result, thermal unevenness of the resulting image display apparatus can be prevented favorably.

The first retardation layer is typically constituted by a stretched film of a resin film. In one embodiment, the thickness of the first retardation layer is preferably 70 µm or less, and more preferably 45 µm to 60 µm. Curl|Karl at the time of bonding can be adjusted favorably, suppressing the curl at the time of a heating favorably that the thickness of a 1st retardation layer is such a range. In addition, in the embodiment in which the first retardation layer is composed of a polycarbonate-based resin film as described later, the thickness of the first retardation layer is preferably 40 µm or less, more preferably 10 µm to 40 µm, and further Preferably, it is 20 micrometers - 30 micrometers. Since the first retardation layer is composed of a polycarbonate-based resin film having such a thickness, it is possible to contribute to the improvement of bending durability and reflection color while suppressing the occurrence of curl.

The first retardation layer 20 may be made of any suitable resin film that can satisfy the above characteristics. Representative examples of such resins include polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, poly and amide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, and acrylic resins. These resins may be used individually or may be used in combination (for example, blending, copolymerization). When the first retardation layer is composed of a resin film exhibiting reverse dispersion wavelength characteristics, a polycarbonate-based resin or a polyestercarbonate-based resin (hereinafter, simply referred to as a polycarbonate-based resin) may be suitably used.

As said polycarbonate-type resin, any suitable polycarbonate-type resin can be used as long as the effect of this invention is acquired. For example, the polycarbonate-based resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, di, tri, or and a structural unit derived from at least one dihydroxy compound selected from the group consisting of polyethylene glycol, and alkylene glycol or spiroglycol. Preferably, the polycarbonate-based resin has a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from alicyclic dimethanol, and/or containing structural units derived from di, tri or polyethylene glycol; More preferably, it includes 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. Polycarbonate-type resin may contain the structural unit derived from another dihydroxy compound as needed. In addition, the details of polycarbonate-type resin which can be used suitably for this invention are, for example, Unexamined-Japanese-Patent No. 2014-10291, Unexamined-Japanese-Patent No. 2014-26266, Unexamined-Japanese-Patent No. 2015-212816. , Japanese Patent Application Laid-Open No. 2015-212817, Japanese Patent Application Laid-Open No. 2015-212818, the description is incorporated herein by reference.

It is preferable that the glass transition temperature of the said polycarbonate-type resin is 110 degreeC or more and 150 degrees C or less, More preferably, they are 120 degrees C 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 organic EL panel 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-based resin may be expressed as reduced viscosity. The reduced viscosity is measured by using methylene chloride as a solvent, precisely preparing the polycarbonate concentration to 0.6 g/dL, and using an Uberod 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 in that the mechanical strength of the molded article becomes small. On the other hand, when reduced viscosity is larger than the said upper limit, the fluidity|liquidity at the time of shaping|molding falls, and the problem that productivity and moldability fall may arise.

As the polycarbonate-based resin film, a commercially available film may be used. Specific examples of the commercially available products include “Pure Ace WR-S” manufactured by Teijin Corporation, “Pure Ace WR-W”, “Pure Ace WR-M” and “NRF” manufactured by Nitto Denko Corporation.

The first retardation layer 20 is obtained, for example, by stretching a film formed from the polycarbonate-based resin. As a method of 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 (eg, a casting method), a calender molding method, a hot pressing method, and the like. 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 obtained. Molding conditions may be appropriately set according to the composition or type of the resin used, characteristics desired for the retardation layer, and the like. In addition, as for polycarbonate-type resin as mentioned above, since many film products are marketed, you may use the said commercially available film for a extending|stretching process as it is.

The thickness of the resin film (unstretched film) can be set to any appropriate value depending on the desired thickness of the first 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, various stretching methods such as free-end stretching, fixed-end stretching, free-end contraction, and fixed-end contraction may be used alone, simultaneously or sequentially. The stretching direction can also be carried out in various directions and 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, the retardation film is produced by uniaxial stretching or fixed-end uniaxial stretching of a resin film. 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 angle θ with respect to the longitudinal direction. By adopting oblique stretching, an elongated 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 is obtained, for example, when laminating with a polarizing film, roll-to-roll This makes it possible to simplify the manufacturing process. Also, the angle θ may be an angle between the absorption axis of the polarizing film and the slow axis of the retardation layer in the polarizing plate with a retardation layer. As described above, the angle θ is preferably 40° to 50°, more preferably 42° to 48°, and still more preferably about 45°.

Examples of the stretching machine used for diagonal stretching include a tenter type stretching machine capable of applying a feeding force or a tensile force or a pulling force at different speeds in the transverse and/or longitudinal directions. As the tenter-type stretching machine, there are a transverse uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine can be used as long as it can continuously diagonally stretch a long resin film.

By appropriately controlling the left and right speeds in the stretching machine, it is possible to obtain a retardation layer (substantially, a long retardation film) having the desired in-plane retardation and a slow axis in the desired direction.

The stretching temperature of the film may vary depending on the in-plane retardation value and thickness desired for the retardation layer, the type of resin used, the thickness of the film used, the draw ratio, and the like. Specifically, the stretching temperature is preferably Tg-30°C to Tg+30°C, more preferably Tg-15°C to Tg+15°C, and most preferably Tg-10°C to Tg+10°C. By stretching at such a temperature, it is possible to obtain the first retardation layer having suitable characteristics in the present invention. In addition, Tg is the glass transition temperature of the constituent material of a film.

D. Second retardation layer

As described above, the second retardation layer may be a so-called positive C plate having a refractive index characteristic of nz>nx=ny. By using the positive C plate as the second retardation layer, reflection in the oblique direction can be prevented favorably, and a wide viewing angle of the antireflection function can be increased. In this case, the retardation Rth (550) in the thickness direction of the second retardation layer is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, still more preferably -90 nm to -200 nm, particularly preferably is -100 nm to -180 nm. Here, 'nx=ny' includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. That is, the in-plane retardation Re (550) of the second retardation layer may be less than 10 nm.

The second retardation layer having a refractive index characteristic of nz>nx=ny may be formed of any suitable material. The second retardation layer is preferably formed of a film comprising a liquid crystal material fixed in homeotropic orientation. The liquid crystal material (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 retardation layer include the liquid crystal compound described in [0020] to [0028] of Japanese Patent Application Laid-Open No. 2002-333642 and a method for forming the retardation layer. In this case, the thickness of the second retardation layer is preferably 0.5 µm to 10 µm, more preferably 0.5 µm to 8 µm, and still more preferably 0.5 µm to 5 µm.

E. Conductive layer or isotropic substrate with conductive layer

The conductive layer may be formed by depositing a metal oxide film on any suitable substrate by any suitable film forming method (eg, vacuum deposition, sputtering, CVD, ion plating, spraying, etc.). Examples of the metal oxide include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Among them, indium-tin composite oxide (ITO) is preferable.

When a conductive layer contains a metal oxide, the thickness of this conductive layer becomes like this. Preferably it is 50 nm or less, More preferably, it is 35 nm or less. The lower limit of the thickness of the conductive layer is preferably 10 nm.

The conductive layer may be transferred from the base material to the first retardation layer (or the second retardation layer if present), and the conductive layer alone may be a constituent layer of a polarizing plate with a retardation layer, or a laminate with a base material (with a conductive layer). As a base material), it may be laminated|stacked on the 1st retardation layer (or 2nd retardation layer if it exists). Preferably, the substrate is optically isotropic, and therefore the conductive layer can be used in a polarizing plate with a retardation layer as an isotropic substrate with a conductive layer.

Any suitable isotropic substrate can be employed as the optically isotropic substrate (isotropic substrate). As the material constituting the isotropic substrate, for example, a material whose main skeleton is a resin not containing a conjugated system, such as a norbornene-based resin or an olefin-based resin, or a cyclic structure such as a lactone ring or a glutarimide ring is incorporated in the main chain of the acrylic resin. and materials containing it. When such a material is used, when an isotropic base material is formed, expression of the phase difference accompanying the orientation of a molecular chain can be suppressed small. The thickness of the isotropic substrate is preferably 50 µm or less, and more preferably 35 µm or less. The lower limit of the thickness of the isotropic substrate is, for example, 20 µm.

The conductive layer and/or the conductive layer of the isotropic substrate with the conductive layer may be patterned as necessary. A conductive portion and an insulating portion may be formed by patterning. As a result, an electrode can be formed. The electrode may function as a touch sensor electrode that senses a contact to the touch panel. Any suitable method can be employ|adopted as a patterning method. Specific examples of the patterning method include a wet etching method and a screen printing method.

F. Image display device

The polarizing plate with a retardation layer as described in the said A to E terms is applicable to an image display apparatus. Accordingly, the present invention includes an image display device using such a polarizing plate with a retardation layer. A liquid crystal display device and an electroluminescent (EL) display device (for example, organic electroluminescent display apparatus, inorganic electroluminescent display apparatus) are mentioned as a representative example of an image display apparatus. The image display apparatus which concerns on embodiment of this invention equips the visual recognition side with the said polarizing plate with a retardation layer as described in the said A to E terms. The polarizing plate with a retardation layer is laminated|stacked so that a retardation layer may become an image display cell (for example, a liquid crystal cell, an organic electroluminescent cell, an inorganic EL cell) side (a polarizing film may become a visual recognition side). In one embodiment, the image display device has a curved shape (substantially a curved display screen), and/or is bendable or bendable. In such an image display apparatus, the effect of the polarizing plate with retardation layer of this invention becomes remarkable.

[Example]

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. The measuring method of each characteristic is as follows. In addition, unless otherwise specified, 'part' and '%' in Examples and Comparative Examples are based on weight.

(1) thickness

The thickness of 10 µm or less was measured using an interference film thickness measuring instrument (manufactured by Otsuka Electronics, product name 'MCPD-3000'). The thickness exceeding 10 μm was measured using a digital micrometer (manufactured by Anritsu Corporation, product name 'KC-351C').

(2) single transmittance, unit absorbance and orthogonal absorbance

For the polarizing plates (protective film / polarizing film) of Examples and Comparative Examples, single transmittance (Ts), parallel transmittance (Tp), orthogonal transmittance ( Tc) was set to Ts, Tp, and Tc of the polarizing film, respectively. These Ts, Tp, and Tc are Y values which were measured by the 2 degree field of view (C light source) of JIS Z8701 and performed visibility correction|amendment. In addition, the refractive index of the protective film was 1.50, and the refractive index of the surface on the opposite side to the protective film of a polarizing film was 1.53.

_{The orthogonal absorbance (A 210} ) was obtained by the following formula from the _{orthogonal transmittance (Tc 210} ) measured at a measurement wavelength of 210 nm using UV-3150 manufactured by Shimadzu Corporation, and divided by the thickness to obtain the unit absorbance. In addition, the orthogonal transmittance (Tc ₄₇₀₎ from the orthogonal absorbance (A ₄₇₀₎ to, and an orthogonal absorbance (A ₆₀₀₎ from the orthogonal transmittance (Tc ₆₀₀₎ of the measurement wavelength 600nm, using each Nippon Bunko Preparation V-7100 in the measurement wavelength 470nm was saved.

Orthogonal absorbance=log10(100/Tc)

In addition, for the A ₄₇₀ and A _600, it is possible to measure the degree equivalent to such Otsuka Denshi produced LPF-200.

(3) iodine concentration

The fluorescence X-ray intensity (kcps) was measured for the polarizing films obtained in Examples and Comparative Examples using a fluorescence X-ray analyzer (manufactured by Rigaku, trade name 'ZSX-PRIMUS II', measurement diameter: φ10 mm). The iodine concentration (weight %) was calculated|required using the following formula from the obtained fluorescent X-ray intensity and thickness.

(iodine concentration)=20.5×(fluorescence X-ray intensity)/(film thickness)

In addition, although the coefficient at the time of calculating a density|concentration differs with a measuring apparatus, the said coefficient can be calculated|required using an appropriate analytical curve. In this Example, a calibration curve was obtained by creating a plurality of samples in which KI (I:K=1:1 (molar ratio)) was added to an arbitrary value in PVA and measuring them.

(4) orthogonal b values

The polarizing plates used in Examples and Comparative Examples were measured using an ultraviolet/visible spectrophotometer (manufactured by Nippon Bunko, product name 'V7100'), and the color in the cross nicol state was obtained. A polarizing plate with a low orthogonal b value (a negative value and a large absolute value) indicates that the color is blue instead of neutral.

(5) Warp

The polarizing plate with retardation layer obtained in the Example and the comparative example was cut out to 110 mm x 60 mm size. At this time, it cut so that the absorption axis direction of a polarizing film might become a long side direction. The cut out polarizing plate with retardation layer was bonded together to the glass plate of 120 mm x 70 mm size and thickness 0.2mm through an adhesive, and it was set as the test sample. The test sample was put into a heating oven maintained at 85°C for 24 hours, and the amount of warpage after taking it out was measured. When the glass plate was turned down and the test sample was left still on a plane, the height of the highest part from the said plane was made into the amount of curvature.

(6) bending durability

The polarizing plate with retardation layer obtained by the Example and the comparative example was cut out to 50 mm x 100 mm size. At this time, it cut so that the absorption axis direction of a polarizing film might become a short side direction. A polarizing plate with a retardation layer cut out under a condition of 20°C and 50%RH using a folding resistance tester with a constant temperature and humidity chamber (manufactured by YUASA, CL09 type-D01) was subjected to a bending test. Specifically, a polarizing plate with a retardation layer is repeatedly bent in a direction parallel to the absorption axis direction so that the retardation layer side is on the outside, and the number of bending until cracks, peeling, film breakage, etc. that cause display defects occur are measured. Thus, it was evaluated according to the following criteria (bending diameter: 2 mmφ).

<Evaluation criteria>

Less than 10,000 cycles: bad

10,000 or more but less than 30,000: Good

30,000 or more: Excellent

(7) front reflection color

The polarizing plate with retardation layer obtained in Examples and Comparative Examples was used as a reflective plate (manufactured by Toray Film Co., Ltd., trade name 'DMS-X42'; reflectance 86%, reflective color without a polarizing plate a ^* = ^{-0.22, b*} =0.32), it bonded on the top, and the measurement sample was produced. At this time, it bonded so that the retardation layer side of a polarizing plate with a retardation layer might oppose a reflecting plate. The measurement sample was measured by the SCE method using a spectrophotometer (CM-2600d manufactured by Konica Minolta), ^{and the values of a *} and b ^* were substituted for √(a ^*2 +b ^*2 ), and the front reflection color was saved.

(8) modulus of elasticity

The film to be measured was molded into a tensile test dumbbell having a parallel portion width of 10 mm and a length of 40 mm based on JIS K6734:2000, and a tensile test was performed in accordance with JIS K7161:1994 to determine the tensile modulus. Here, the longitudinal direction generally coincides with the stretching direction of the polarizing film.

[Example 1]

1. Fabrication of the polarizing film

As the thermoplastic resin substrate, an amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 µm) having a long, water absorption rate of 0.75% and a Tg of about 75°C was used. Corona treatment was performed on one side of the resin substrate.

Polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name 'Gosefaimer Z410') in a ratio of 9: 1 to 100 parts by weight of a PVA-based resin mixed with potassium iodide 13 parts by weight was added and dissolved in water to prepare an aqueous PVA solution (coating solution).

The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer having a thickness of 8 μm to prepare a laminate.

The obtained laminate was uniaxially stretched at the free end by 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds in an oven at 130°C (air-assisted stretching treatment).

Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilization treatment).

Then, the single transmittance (Ts) and wavelength of the polarizing film finally obtained in a dyeing bath (an aqueous solution of iodine obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30° C. It was immersed for 60 seconds while adjusting a density|concentration so that a unit absorbance might become a desired value (dyeing process).

Then, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide with respect to 100 parts by weight of water and 5 parts by weight of boric acid) with a liquid temperature of 40°C for 30 seconds (crosslinking treatment).

Thereafter, while the laminate was immersed in a boric acid aqueous solution (boric acid concentration of 4.0% by weight) at a liquid temperature of 70° C., uniaxial stretching was performed between rolls having different circumferential speeds so that the total draw ratio in the longitudinal direction (longitudinal direction) was 5.5 times. (underwater stretching treatment).

Thereafter, the laminate was immersed in a washing bath (aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) having a liquid temperature of 20°C (washing treatment).

Then, while drying in the oven maintained at 90 degreeC, it was made to contact with the heating roll made from SUS whose surface temperature was maintained at 75 degreeC for about 2 second (dry shrinkage process). The shrinkage ratio in the width direction of the laminate by the drying shrinkage treatment was 2.5%.

In this way, a polarizing film having a thickness of 3.4 µm was formed on the resin substrate.

2. Fabrication of polarizing plate

A cycloolefin-based film (thickness: 28 µm, elastic modulus: 2100 MPa) with a hard coat layer (refractive index: 1.53) as a protective layer is bonded to the surface (surface opposite to the resin substrate) of the polarizing film obtained above via an ultraviolet curable adhesive. did. Specifically, it coated so that the total thickness of a curable adhesive might be set to 1.0 micrometer, and it bonded together using the roll machine. Thereafter, UV rays were irradiated from the protective layer side to cure the adhesive. Next, after slitting both ends, the resin base material was peeled, and the elongate polarizing plate (width: 1300 mm) which has the structure of a protective layer/adhesive layer/polarizing film was obtained. The single transmittance of the polarizing film was 43.5%, the unit absorbance at a wavelength of 210 nm was 0.45, A ₄₇₀ /A ₆₀₀ was 0.76, and the orthogonal b value was -3.6.

3. Preparation of retardation film constituting retardation layer

3-1. Polymerization of polyester carbonate-based resins

Polymerization was carried out using a batch polymerization apparatus including two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100°C. Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane 29.60 parts by mass (0.046 mol), isosorbide (ISB) 29.21 parts by mass (0.200 mol), spiroglycol (SPG) 42.28 mass Parts (0.139 mol), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19×10 ^-2 parts by mass (6.78×10 ^-5 mol) of calcium acetate monohydrate as a catalyst were added. After replacing the inside of the reactor with reduced pressure nitrogen, heating was performed with a heating medium, and stirring was started when the internal temperature reached 100°C. The internal temperature was made to reach 220 degreeC 40 minutes after the start of temperature increase, and while controlling so that this temperature might be maintained, pressure reduction was started, and it was set to 13.3 kPa in 90 minutes after reaching 220 degreeC. The phenol vapor produced by the polymerization reaction was led to a reflux condenser at 100° C., the monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the uncondensed phenol vapor was led to the condenser at 45° C. and recovered. After nitrogen was introduced into the first reactor and the pressure was returned to atmospheric pressure, the oligomerized reaction solution in the first reactor was transferred to the second reactor. Then, the temperature rise and pressure reduction in the 2nd reactor were started, and it was set as the internal temperature of 240 degreeC and the pressure of 0.2 kPa in 50 minutes. Thereafter, polymerization was allowed to proceed until a predetermined stirring power was reached. When a predetermined power was reached, nitrogen was introduced into the reactor and the pressure was restored, and the resulting polyester carbonate-based resin was extruded into water, and the strands were cut to obtain pellets.

3-2. Production of retardation film

After vacuum drying the obtained polyester carbonate-based resin (pellet) at 80 ° C. for 5 hours, a single screw extruder (manufactured by Toshiba Machinery Co., Ltd., cylinder set temperature: 250 ° C), T-die (width 200 mm, set temperature: 250 ° C), A 130-micrometer-thick long resin film was produced using the film film forming apparatus provided with the cooling roll (set temperature: 120-130 degreeC) and the winder. The obtained elongate resin film was stretched while adjusting so that a desired retardation could be obtained to obtain a retardation film having a thickness of 48 µm. The stretching conditions were a stretching temperature of 143°C and a stretching ratio of 2.8 times in the width direction. Re(550) of the obtained retardation film was 141 nm, Re(450)/Re(550) was 0.86, and Nz coefficient was 1.12.

4. Preparation of polarizing plate with retardation layer

The retardation film obtained in said 3. was bonded together on the polarizing film surface of the polarizing plate obtained in said 2. via an acrylic adhesive (5 micrometers in thickness). At this time, it bonded together so that the absorption axis of a polarizing film and the slow axis of retardation film might make an angle of 45 degrees. In this way, a polarizing plate with a retardation layer having the structure of a protective layer/adhesive layer/polarizing film/adhesive layer/retardation layer was obtained. The total thickness of the obtained polarizing plate with retardation layer was 85 micrometers. The obtained polarizing plate with retardation layer was used for evaluation of said (5)-(6). A result is shown in Table 1.

[Example 2-1]

1. Fabrication of the polarizing film

The thickness of the polarizing film obtained by changing the application thickness of the PVA aqueous solution (coating solution) to 13 µm was 4.6 µm, and the concentration of the dyeing bath was adjusted so that the single transmittance (Ts) of the polarizing film was 43.0%. It carried out similarly to Example 1, and formed the polarizing film on the resin base material.

2. Fabrication of polarizing plate

Except having used the polarizing film obtained in said 1., it carried out similarly to Example 1, and produced the polarizing plate which has the structure of a protective layer/adhesive layer/polarizing film. The single transmittance of the polarizing plate (substantially, the polarizing film) was 43.0%, and the polarization degree was 99.995%. In addition, the unit absorbance at a wavelength of 210 nm was 0.70, A ₄₇₀ /A ₆₀₀ was 0.87, and the orthogonal b value was -3.0.

3. Preparation of retardation film

The long 130-micrometer-thick polyester carbonate resin film obtained by carrying out similarly to Example 1 was extended|stretched in the width direction, adjusting so that a predetermined|prescribed retardation might be obtained, and the 48-micrometer-thick retardation film was obtained. Re (550) of the obtained retardation film was 144 nm.

4. Preparation of polarizing plate with retardation layer

In the same manner as in Example 1, the retardation film obtained in the above 3. was bonded to the surface of the polarizing film of the polarizing plate obtained in the above 2. A polarizing plate with a retardation layer having the configuration of a protective layer / adhesive layer / polarizer / adhesive layer / retardation layer was produced did. The total thickness of the obtained polarizing plate with retardation layer was 87 micrometers. The obtained polarizing plate with retardation layer was used for evaluation of said (5)-(7). A result is shown in Table 1.

[Example 2-2]

1. Fabrication of the polarizing film

A polarizing film was formed on the resin substrate in the same manner as in Example 2-1, except that the concentration of the dyeing bath was adjusted so that the single transmittance (Ts) of the polarizing film was 44.0%.

2. Fabrication of polarizing plate

Except having used the polarizing film obtained in said 1., it carried out similarly to Example 1, and produced the polarizing plate which has the structure of a protective layer/adhesive layer/polarizing film. The single transmittance of the polarizing plate (substantially, the polarizing film) was 44.0%, and the polarization degree was 99.96%. In addition, the unit absorbance at a wavelength of 210 nm was 0.50, A ₄₇₀ /A ₆₀₀ was 0.87, and the orthogonal b value was -5.0.

3. Preparation of polarizing plate with retardation layer

In the same manner as in Example 1, the retardation film obtained in the same manner as in Example 2-1 was bonded to the surface of the polarizing film of the polarizing plate obtained in 2. above, and the retardation layer having the configuration of a protective layer/adhesive layer/polarizer/adhesive layer/retardation layer An attached polarizing plate was produced. The total thickness of the obtained polarizing plate with retardation layer was 87 micrometers. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 2-1. A result is shown in Table 1.

[Example 3-1]

1. Fabrication of the polarizing film

It carried out similarly to Example 2-1, and formed the 4.6-micrometer-thick polarizing film on the resin base material.

2. Fabrication of polarizing plate

Example 1, except that the polarizing film obtained in 1. above was used, and a triacetyl cellulose (TAC) film with a hard coat layer (hard coat layer thickness of 7 µm, TAC thickness of 25 µm, elastic modulus: 3600 MPa) was used as a protective layer Similarly, the polarizing plate which has the structure of a protective layer/adhesive layer/polarizing film was produced.

3. Preparation of retardation film constituting retardation layer

After vacuum drying the polyester carbonate-based resin (pellet) obtained in the same manner as in Example 1 at 80° C. for 5 hours except that 0.7 parts by mass of PMMA was melt-kneaded, a single screw extruder (manufactured by Toshiba Machinery, cylinder set temperature: 250 ° C), a T-die (width 200 mm, set temperature: 250 ° C), a cooling roll (set temperature: 120 to 130 ° C), and a film forming apparatus equipped with a winder to prepare a long resin film having a thickness of 105 µm. The obtained elongate resin film was stretched 2.8 times in the width direction at 138°C while adjusting so that a predetermined retardation could be obtained, to obtain a retardation film having a thickness of 38 µm. Re(550) of the obtained retardation film was 144 nm, and Re(450)/Re(550) was 0.86.

4. Preparation of polarizing plate with retardation layer

The retardation film obtained in said 3. was bonded to the polarizing film surface of the polarizing plate obtained in said 2. via the acrylic adhesive (5 micrometers in thickness). At this time, it bonded together so that the absorption axis of a polarizing film and the slow axis of retardation film might make an angle of 45 degrees. In this way, a polarizing plate with a retardation layer having the structure of a protective layer/adhesive layer/polarizing film/adhesive layer/retardation layer was obtained. The total thickness of the obtained polarizing plate with retardation layer was 81 micrometers. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 2-1. A result is shown in Table 1.

[Example 3-2]

A long polyester carbonate resin film having a thickness of 105 µm obtained in the same manner as in Example 3-1 was stretched in the width direction while adjusting so that a predetermined retardation could be obtained to obtain a retardation film having a thickness of 38 µm. Re (550) of the obtained retardation film was 140 nm.

A polarizing plate with a retardation layer having the configuration of a protective layer/adhesive layer/polarizing film/adhesive layer/retardation layer was obtained in the same manner as in Example 3-1 except that the retardation film was used as the retardation layer. The total thickness of the obtained polarizing plate with retardation layer was 81 micrometers. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 2-1. A result is shown in Table 1.

[Example 3-3]

A long polyester carbonate resin film having a thickness of 105 µm obtained in the same manner as in Example 3-1 was stretched in the width direction while adjusting so that a predetermined retardation could be obtained to obtain a retardation film having a thickness of 38 µm. Re (550) of the obtained retardation film was 149 nm.

A polarizing plate with a retardation layer having the configuration of a protective layer/adhesive layer/polarizing film/adhesive layer/retardation layer was obtained in the same manner as in Example 3-1 except that the retardation film was used as the retardation layer. The total thickness of the obtained polarizing plate with retardation layer was 81 micrometers. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 2-1. A result is shown in Table 1.

[Example 4-1]

1. Fabrication of the polarizing film

It carried out similarly to Example 2-2, and formed the 4.6-micrometer-thick polarizing film on the resin base material.

2. Fabrication of polarizing plate

Except having used the polarizing film obtained in 1. above, it carried out similarly to Example 3-1, and produced the polarizing plate which has the structure of a protective layer/adhesive layer/polarizing film.

3. Preparation of polarizing plate with retardation layer

The retardation film produced in the same manner as in Example 3-1 was bonded to the polarizing film surface of the polarizing plate obtained in 2. above in the same manner as in Example 3-1. Thus, the polarizing plate with a retardation layer which has the structure of a protective layer/adhesive layer/polarizing film/adhesive layer/retardation layer was obtained. The total thickness of the obtained polarizing plate with retardation layer was 81 micrometers. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 2-1. A result is shown in Table 1.

[Example 4-2]

1. Fabrication of the polarizing film

It carried out similarly to Example 2-2, and formed the 4.6-micrometer-thick polarizing film on the resin base material.

2. Fabrication of polarizing plate

Except having used the polarizing film obtained in 1. above, it carried out similarly to Example 3-1, and produced the polarizing plate which has the structure of a protective layer/adhesive layer/polarizing film.

3. Preparation of polarizing plate with retardation layer

The retardation film produced by carrying out similarly to Example 3-2 was carried out similarly to Example 3-1 on the polarizing film surface of the polarizing plate obtained in said 2., and was bonded together. Thus, the polarizing plate with a retardation layer which has the structure of a protective layer/adhesive layer/polarizing film/adhesive layer/retardation layer was obtained. The total thickness of the obtained polarizing plate with retardation layer was 81 micrometers. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 2-1. A result is shown in Table 1.

[Example 5]

The polycarbonate resin film obtained by carrying out similarly to Example 1 was diagonally stretched by the method according to Example 2 of Unexamined-Japanese-Patent No. 2014-194483, and the 58-micrometer-thick retardation film was obtained. Re(550) of the obtained retardation film was 144 nm, Re(450)/Re(550) was 0.86, Nz coefficient was 1.21, and the orientation angle (direction of a slow axis) was 45 degrees with respect to a long direction. This retardation film and the polarizing plate of Example 2-2 are laminated by roll-to-roll through an acrylic pressure-sensitive adhesive (thickness of 5 µm), and with a retardation layer having the configuration of a protective layer/adhesive layer/polarizing film/adhesive layer/retardation layer A polarizing plate was obtained. The total thickness of the obtained polarizing plate with retardation layer was 97 micrometers. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 2-1. A result is shown in Table 1.

[Comparative Example 1]

1. Fabrication of polarizer

A polyvinyl alcohol-based resin film having an average degree of polymerization of 2,400, a degree of saponification of 99.9 mol%, and a thickness of 30 μm was prepared. The polyvinyl alcohol film was immersed in a swelling bath (water bath) at 20° C. for 30 seconds between rolls having different circumferential speed ratios, and stretched 2.4 times in the conveying direction while swelling (swelling step), followed by a 30° C. dyeing bath (iodine concentration was The original polyvinyl alcohol film (polyvinyl alcohol film that is not stretched at all in the conveying direction) was immersed in an aqueous solution having a concentration of 0.03% by weight and potassium iodide of 0.3% by weight) so that the single transmittance after final stretching becomes a desired value and dyed. It stretched 3.7 times in the conveyance direction as a reference|standard (dyeing process). The immersion time at this time was about 60 second. Next, while immersing the dyed polyvinyl alcohol film in a crosslinking bath at 40°C (aqueous solution having a boric acid concentration of 3.0% by weight and potassium iodide concentration of 3.0% by weight), 4.2 times in the conveying direction based on the original polyvinyl alcohol film. It was stretched until (crosslinking step). Further, the obtained polyvinyl alcohol film was immersed in a stretching bath at 64° C. (aqueous solution having a boric acid concentration of 4.0% by weight and potassium iodide concentration of 5.0% by weight) for 50 seconds, and 6.0 in the conveying direction based on the original polyvinyl alcohol film. After extending|stretching to twice (stretching process), it was immersed for 5 second in 20 degreeC washing|cleaning bath (aqueous solution with a potassium iodide concentration of 3.0 weight%) (washing process). The wash|cleaned polyvinyl alcohol film was dried at 30 degreeC for 2 minute(s), and the polarizer (12 micrometers in thickness) was produced.

2. Fabrication of polarizing plate

As an adhesive, an aqueous solution containing polyvinyl alcohol resin (average degree of polymerization of 1,200, degree of saponification of 98.5 mol%, degree of acetoacetylation of 5 mol%) and methylolmelamine containing an acetoacetyl group was used. This adhesive was used so that the thickness of the adhesive layer was 0.1 µm, and on one side of the polarizer obtained above, a triacetyl cellulose (TAC) film with a hard coat layer (hard coat layer thickness of 7 µm, TAC thickness of 25 µm, elastic modulus: 3600 MPa ) to the other side of the polarizer, after bonding a TAC film having a thickness of 25 μm with a roll bonding machine, heat-drying in an oven (temperature 60° C., time for 5 minutes), protective layer 1 (thickness 32 μm)/adhesive layer/polarizer/adhesive layer/protective layer (2) to prepare a polarizing plate.

3. Preparation of polarizing plate with retardation layer

On the surface of the protective layer (2) of the polarizing plate obtained in the above 2, the retardation film was bonded together in the same manner as in Example 1, and the protective layer (1)/adhesive layer/polarizer/adhesive layer/protective layer (2)/adhesive layer/retardation layer A polarizing plate with a retardation layer having a configuration of was produced. The total thickness of the obtained polarizing plate with retardation layer was 122 micrometers. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 2-1.

[Comparative Example 2]

1. Fabrication of polarizer

It carried out similarly to the comparative example 1, and produced the polarizer (12 micrometers in thickness).

2. Fabrication of polarizing plate

It carried out similarly to the comparative example 1, and produced the polarizing plate which has the structure of the protective layer 1 (32 micrometers in thickness)/adhesive layer/polarizer/adhesive layer/protective layer 2 (25 micrometers in thickness).

3. Preparation of the first alignment-solidified layer and the second alignment-solidified layer constituting the retardation layer

10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name 'Paliocolor LC242', represented by the following formula), and a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF: trade name 'Irgacure 907') 3 g was dissolved in 40 g of toluene to prepare a liquid crystal composition (coating solution).

The surface of a polyethylene terephthalate (PET) film (thickness of 38 µm) was rubbed using a rubbing cloth, followed by orientation treatment. The direction of orientation treatment was made so that it might become a 15 degree direction as seen from the visual recognition side with respect to the direction of the absorption axis of a polarizer when bonding to a polarizing plate. The liquid crystal compound was orientated by coating the said liquid crystal coating liquid on the surface of this orientation treatment with a bar coater, and heating and drying at 90 degreeC for 2 minute(s). The liquid crystal layer formed in this way was irradiated with light of 1 mJ/cm 2 using a metal halide lamp, and the liquid crystal layer was cured to form a liquid crystal alignment solidified layer A on the PET film. The thickness of the liquid-crystal alignment solidification layer A was 2.5 micrometers, and the in-plane retardation Re(550) was 270 nm. Moreover, the liquid-crystal orientation solidification layer A had refractive index distribution of nx>ny=nz.

A liquid-crystal alignment solidification layer B was formed on the PET film in the same manner as above except that the coating thickness was changed and the orientation treatment direction was set to be a 75° direction when viewed from the visual side with respect to the direction of the absorption axis of the polarizer. The thickness of the liquid-crystal alignment solidification layer B was 1.5 micrometers, and in-plane retardation Re(550) was 140 nm. Moreover, the liquid-crystal orientation solidification layer B had refractive index distribution of nx>ny=nz. Moreover, Re(450)/Re(550) of liquid-crystal orientation solidified layers A and B was 1.11.

4. Preparation of polarizing plate with retardation layer

The liquid-crystal orientation-solidified layer A and the liquid-crystal orientation-solidified layer B obtained in said 3. were transcribed in this order to the surface by the side of the protective layer (2) of the polarizing plate obtained in said 2. At this time, transfer (bonding) was performed so that the angle between the absorption axis of the polarizer and the slow axis of the alignment-solidified layer A was 15°, and the angle formed between the absorption axis of the polarizer and the slow axis of the alignment-solidified layer B was 75°. . In addition, each transcription|transfer (bonding) was performed through the ultraviolet curable adhesive (1 micrometer in thickness). In this way, the protective layer (1) / adhesive layer / polarizer / adhesive layer / protective layer (2) / adhesive layer / retardation layer (first alignment solidified layer / adhesive layer / second alignment solidified layer) having the configuration of a polarizing plate with a retardation layer got it The total thickness of the obtained polarizing plate with retardation layer was 75 micrometers. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 2-1. A result is shown in Table 1.

[Comparative Example 3]

1. Fabrication of the polarizing film

It carried out similarly to Example 2-1, and formed the 4.6-micrometer-thick polarizing film on the resin base material.

2. Fabrication of polarizing plate

An acrylic film (surface refractive index 1.50, 20 µm) as a protective layer was bonded to the surface (surface opposite to the resin substrate) of the polarizing film obtained above through an ultraviolet curable adhesive. Specifically, it coated so that the total thickness of a curable adhesive might be set to 1.0 micrometer, and it bonded together using the roll machine. Thereafter, UV rays were irradiated from the protective layer side to cure the adhesive. Next, after slitting both ends, the resin base material was peeled, and the elongate polarizing plate (width: 1300 mm) which has the structure of a protective layer/adhesive layer/polarizing film was obtained.

3. Preparation of polarizing plate with retardation layer

It carried out similarly to Comparative Example 2, and to the polarizing film surface of the polarizing plate obtained in said 2., the liquid-crystal orientation solidified layer A and liquid-crystal orientation solidified layer B obtained by carrying out similarly to Comparative Example 2 were transcribed in this order. In this way, a polarizing plate with a retardation layer having the structure of a protective layer/adhesive layer/polarizing film/adhesive layer/retardation layer (first alignment-solidified layer/adhesive layer/second alignment-solidified layer) was obtained. The total thickness of the obtained polarizing plate with retardation layer was 32 micrometers. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 2-1. A result is shown in Table 1.

[Comparative Example 4]

Potassium iodide was not added to the PVA aqueous solution (coating solution), the thickness of the polarizing film obtained by changing the PVA aqueous solution (coating solution) was 3.3 μm, and the shrinkage rate in the width direction without using a heating roll in the drying shrinkage treatment was A polarizing film and a polarizing plate were produced in the same manner as in Example 1 except that the concentration of the polarizing film was adjusted to 0.1% or less and the concentration of the dyeing bath was adjusted. The single transmittance of the polarizing plate (substantially, the polarizing film) was 43.4% and the unit absorbance at a wavelength of 210 nm was 1.32. Except having used this polarizing plate, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer.

[Table 1]

[evaluation]

As is clear from comparing Example 1 with Comparative Examples 1, 2 and 4, the polarizing film produced by a predetermined method is thin and exhibits excellent optical properties. It turns out that by using such a polarizing film, it is thin, has the outstanding optical characteristic, and the curvature after a heating test was suppressed remarkably (as a result, it was excellent in handleability) that a polarizing plate with a retardation layer is obtained. In addition, it can be seen that an excellent reflection color can be obtained by using in combination with a retardation layer composed of a polycarbonate-based resin (including polyester carbonate-based resin) film. In addition, the thickness of the polycarbonate-based resin is made thin to 40 µm or less, the total thickness of the polarizing plate with a retardation layer is 85 µm or less, and a substrate having an elastic modulus of 3000 MPa or more, preferably a TAC film, is used as a protective layer. This could be further improved. On the other hand, the polarizing plate with a retardation layer of Comparative Example 3 was thin and had excellent optical properties, and the warpage after the heating test was remarkably suppressed, but the reflection color was large and not satisfactory in terms of display properties.

Industrial Applicability

The polarizing plate with retardation layer of this invention is used suitably as a circular polarizing plate for liquid crystal display devices, organic electroluminescent display devices, and inorganic electroluminescent display devices.

10: polarizer
11: Polarizing film
12: first protective layer
13: second protective layer
20: retardation layer
100: polarizing plate with retardation layer
101: polarizing plate with retardation layer

Claims (17)

A polarizing film and a polarizing plate including a protective layer on at least one side of the polarizing film, and a retardation layer,
The polarizing film is composed of a polyvinyl alcohol-based resin film containing a dichroic material, the thickness of which is 8 μm or less, and the orthogonal absorbance per 1 μm in thickness at a wavelength of 210 nm is 1.00 or less,
Re (550) of the retardation layer is 100 nm to 190 nm, Re (450) / Re (550) is 0.8 or more and less than 1,
An angle between the slow axis of the retardation layer and the absorption axis of the polarizing film is 40° to 50°,
Polarizing plate with retardation layer. According to claim 1,
The polarizing plate with a retardation layer in which the said protective layer is comprised from the base material with an elasticity modulus of 3000 MPa or more. 3. The method of claim 1 or 2,
The total thickness is 90 μm or less,
The front reflection color is 3.5 or less,
The polarizing plate with a retardation layer in which the said protective layer is comprised from the resin film whose elasticity modulus is 3000 MPa or more. 4. The method according to any one of claims 1 to 3,
A polarizing plate with a retardation layer, wherein the protective layer is composed of a triacetyl cellulose-based resin film. 5. The method according to any one of claims 1 to 4,
The polarizing plate includes the polarizing film and the protective layer disposed on only one side of the polarizing film,
The polarizing plate with a retardation layer in which the said retardation layer is bonded to the said polarizing film via an adhesive layer. 6. The method according to any one of claims 1 to 5,
A polarizing plate with a retardation layer, wherein the retardation layer is composed of a polycarbonate-based resin film. 7. The method according to any one of claims 1 to 6,
A polarizing plate with a retardation layer, wherein the retardation layer is composed of a polycarbonate-based resin film having a thickness of 40 μm or less. 8. The method according to any one of claims 1 to 7,
A polarizing plate with a retardation layer, wherein the ratio (A ₄₇₀ /A ₆₀₀ ) of the orthogonal absorbance (A ₄₇₀ ) at a wavelength of 470 nm to the orthogonal absorbance (A _{600 ) at a wavelength of 600 nm of the polarizing film is 0.7 to 2.00.} 9. The method according to any one of claims 1 to 8,
A polarizing plate with a retardation layer, wherein the orthogonal b value of the polarizing film is greater than -10 and less than or equal to +10. 10. The method according to any one of claims 1 to 9,
The polarizing plate with a retardation layer, wherein the iodine concentration of the said polarizing film is 3.0 weight% or more. 11. The method according to any one of claims 1 to 10,
A polarizing plate with a retardation layer, wherein the single transmittance of the polarizing film is 42.5% or more. 12. The method according to any one of claims 1 to 11,
A polarizing plate with a retardation layer, further comprising another retardation layer outside the retardation layer, wherein the refractive index characteristic of the other retardation layer exhibits a relationship of nz>nx=ny. 13. The method according to any one of claims 1 to 12,
A polarizing plate with a retardation layer further comprising an isotropic substrate with a conductive layer or a conductive layer on the outside of the retardation layer. 14. The method according to any one of claims 1 to 13,
long,
The polarizing film has an absorption axis in a long direction,
A polarizing plate with a retardation layer, wherein the retardation layer is an obliquely stretched film having a slow axis in a direction forming an angle of 40° to 50° with respect to a long direction. 15. The method of claim 14,
A polarizing plate with a retardation layer wound in roll shape. An image display device provided with the polarizing plate with a retardation layer in any one of Claims 1-13. 17. The method of claim 16,
The image display apparatus which is an organic electroluminescent display apparatus or an inorganic electroluminescent display apparatus.

Images