WO2020080173A1

WO2020080173A1 - Polarizing plate with phase difference layer, and image display device using this

Info

Publication number: WO2020080173A1
Application number: PCT/JP2019/039580
Authority: WO
Inventors: 後藤　周作; 寛教柳沼; 寛友久; 清水　享
Original assignee: 日東電工株式会社
Priority date: 2018-10-15
Filing date: 2019-10-08
Publication date: 2020-04-23

Abstract

A polarizing plate with a phase difference layer is provided which is thin, has excellent handling, and excellent optical characteristics. The polarizing plate with a phase difference layer comprises a polarizing plate, which includes a polarizing film, and a protection layer on at least one side of the polarizing film, and a phase difference layer. The polarizing film is configured from a polyvinyl alcohol-base resin film containing a dichroic substance, and is at most 8 μm thick, and the orthogonal absorbance per 1 μm thickness at the wavelength 210 nm is less than or equal to 1.00. Re(550) of the phase difference layer is 100-190 nm, and Re(450)/Re(550) is greater than or equal to 0.8 and less than 1. The angle formed between the slow axis of the phase difference layer and the absorption axis of the polarizing membrane is 40°-50°.

Description

Polarizing plate with retardation layer and image display device using the same

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

In recent years, image display devices represented by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices and inorganic EL display devices) have rapidly become popular. A polarizing plate and a retardation plate are typically used for the image display device. 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), and recently, there is a strong demand for thinner image display devices. Accordingly, there is an increasing demand for thinner polarizing plates with retardation layers. Further, in recent years, there has been an increasing demand for a curved image display device and / or an image display device that can be bent or bent, and thus a polarizing plate and a polarizing plate with a retardation layer are required to be thinner and more flexible. ing. For the purpose of reducing the thickness of the polarizing plate with a retardation layer, the thickness of the protective layer of the polarizing film and the retardation film, which make a large contribution to the thickness, has been reduced. However, when the protective layer and the retardation film are made thin, the influence of the shrinkage of the polarizing film becomes relatively large, which causes the problems of warpage of the image display device and deterioration of the operability of the polarizing plate with the retardation layer.

▽ In order to solve the above problems, it is necessary to make the polarizing film thinner as well. However, if the thickness of the polarizing film is simply reduced, the optical characteristics will deteriorate. More specifically, one or both of the polarization degree and the single-body transmittance, which are in a trade-off relationship, are reduced to a practically unacceptable level. As a result, the optical characteristics of the polarizing plate with the retardation layer are also insufficient.

Japanese Patent No. 3325560

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

The polarizing plate with a retardation layer of the present invention has a polarizing plate including a polarizing film, 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, has a thickness of 8 μm or less, and has an orthogonal absorbance of 1.00 or less per 1 μm of thickness at a wavelength of 210 nm. 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, and the slow axis of the retardation layer and the absorption axis of the polarizing film. The angle formed by and is 40 ° to 50 °.
In one embodiment, the protective layer is composed of a base material having an elastic modulus of 3000 MPa or more.
In one embodiment, the polarizing plate with a retardation layer has a total thickness of 90 μm or less, a front reflection hue of 3.5 or less, and the protective layer is made of a resin film having an elastic modulus of 3000 MPa or more. Composed.
In one embodiment, the protective layer is composed of a triacetyl cellulose resin film.
In one embodiment, the polarizing plate includes the polarizing film and the protective layer arranged only on one side of the polarizing film, and the retardation layer includes the polarizing film via an adhesive layer. Are pasted together.
In one embodiment, the above-mentioned retardation layer comprises a polycarbonate 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 and 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 +10 or less.
In one embodiment, the iodine concentration of the polarizing film is 3.0% by weight or more.
In one embodiment, the single transmittance of the polarizing film is 42.5% or more.
In one embodiment, the polarizing plate with a retardation layer further has another retardation layer outside the retardation layer, and the refractive index characteristic of the another retardation layer is nz> nx = ny. Show the relationship.
In one embodiment, the above-mentioned polarizing plate with a retardation layer further has a conductive layer or an isotropic substrate with a conductive layer outside the above-mentioned retardation layer.
In one embodiment, the polarizing plate with a retardation layer is elongated, the polarizing film has an absorption axis in the longitudinal direction, and the retardation layer is 40 ° to 40 ° with respect to the longitudinal direction. It is an obliquely stretched film having a slow axis in a direction forming an angle of 50 °. In one embodiment, the polarizing plate with a retardation layer is wound in a roll shape.
According to another aspect of the present invention, an image display device is provided. This image display device includes the above polarizing plate with a retardation layer.
In one embodiment, the image display device is an organic electroluminescence display device or an inorganic electroluminescence display device.

According to the present invention, addition of a halide (typically potassium iodide) to a polyvinyl alcohol (PVA) -based resin, two-stage stretching including auxiliary stretching in air and stretching in water, and drying and shrinking with a heating roll. By adopting in combination, it is possible to obtain a polarizing film that is thin and has extremely excellent optical characteristics. By using such a polarizing film, it is possible to realize a polarizing plate with a retardation layer, which is thin, has excellent handleability, and has excellent optical characteristics.

1 is a schematic sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another embodiment of the present invention. It is a schematic diagram showing an example of dry shrinkage processing using a heating roll in a manufacturing method of a polarizing film used for a polarizing plate with a phase contrast layer of the present invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

(Definition of terms and symbols)
The 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 maximum (that is, the slow axis direction), and “ny” is the direction in the plane that is orthogonal to the slow axis (that is, the fast axis direction). , And "nz" is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
“Re (λ)” is an 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) is calculated by the formula: Re (λ) = (nx−ny) × d, where d (nm) is the thickness of the layer (film).
(3) Phase difference in the thickness direction (Rth)
“Rth (λ)” is a phase difference in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. For example, “Rth (550)” is a phase difference in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Rth (λ) is calculated by the formula: Rth (λ) = (nx−nz) × d, where d (nm) is the thickness of the layer (film).
(4) Nz coefficient The Nz coefficient is calculated by Nz = Rth / Re.
(5) Angle When an angle is referred to in this specification, the angle includes both clockwise and counterclockwise rotations with respect to the reference direction. Therefore, for example, “45 °” means ± 45 °.

A. Overall Configuration of Polarizing Plate with Retardation Layer FIG. 1 is a schematic sectional view of a polarizing plate with a retardation layer according to an embodiment of the present invention. The polarizing plate 100 with a retardation layer of this embodiment includes a polarizing plate 10 and a retardation layer 20. The polarizing plate 10 includes a polarizing film 11, a first protective layer 12 arranged on one side of the polarizing film 11, and a second protective layer 13 arranged on the other side of the polarizing film 11. . 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 for 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 (hereinafter referred to as unit absorbance) per 1 μm thickness at a wavelength of 210 nm is 1.00 or less.

As shown in FIG. 2, a retardation layer-attached polarizing plate 101 according to another embodiment may be provided with another retardation layer 50 and / or a conductive layer or an isotropic substrate 60 with a conductive layer. Another retardation layer 50 and the conductive layer or the isotropic substrate 60 with a conductive layer are typically provided outside the retardation layer 20 (on the side opposite to the polarizing plate 10). Another retardation layer typically has a refractive index characteristic of nz> nx = ny. Another 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 different retardation layer 50 and the conductive layer or the isotropic substrate 60 with a conductive layer are typically arbitrary layers provided as needed, and either one or both may be omitted. Note that, for convenience, the retardation layer 20 may be referred to as a first retardation layer, and another retardation layer 50 may be referred to as a second retardation layer. When a conductive layer or an isotropic base material with a conductive layer is provided, the polarizing plate with a retardation layer is a so-called inner layer in which a touch sensor is incorporated between an image display cell (for example, an organic EL cell) and the polarizing plate. It can be applied to a touch panel type input display 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. Further, the angle formed by the slow axis of the first retardation layer 20 and the absorption axis of the polarizing film 11 is 40 ° to 50 °.

The above-described embodiments may be combined as appropriate, and the components in the above-described embodiments may be modified as is obvious in the art. For example, the configuration in which the isotropic substrate 60 with a conductive layer is provided outside the second retardation layer 50 is replaced with an optically equivalent configuration (for example, a laminate of the second retardation layer and the conductive layer). Good.

The polarizing plate with a retardation layer according to the embodiment of the present invention may further include another retardation layer. Other optical properties of the retardation layer (for example, refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position and the like can be appropriately set according to the purpose.

The polarizing plate with a retardation layer of the present invention may have a sheet-like shape or a long shape. In the present specification, "long shape" means an elongated shape having a length sufficiently longer than the width, and for example, an elongated shape having a length 10 times or more, preferably 20 times or more the width. Including. The long polarizing plate with a retardation layer can be wound into a roll. When the polarizing plate with a retardation layer is elongated, the polarizing plate and the retardation layer are also elongated. In this case, the polarizing film preferably has an absorption axis in the longitudinal 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 lengthwise direction. If the polarizing film and the first retardation layer have such a configuration, the polarizing plate with the retardation layer can be produced by roll-to-roll.

In practice, an adhesive layer (not shown) is provided on the opposite side of the retardation layer to the polarizing plate, and the polarizing plate with retardation layer can be attached to the image display cell. Further, it is preferable that a release film is temporarily attached to the surface of the pressure-sensitive adhesive layer until the polarizing plate with a retardation layer is used. By temporarily attaching the release film, the pressure-sensitive adhesive layer can be protected and the roll can be formed.

The front reflection hue (√ (a ^{* 2} + b ^{* 2} )) of the polarizing plate with a retardation layer is preferably 3.5 or less, more preferably 3.0 or less. When the front reflection hue is within the above range, undesired coloring is suppressed, and as a result, a polarizing plate with a retardation layer having excellent 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, even more preferably 100 μm or less, even more preferably 90 μm or less, still more preferably 85 μm or less. is there. The lower limit of the total thickness can 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 can have extremely excellent flexibility and bending durability. Such a polarizing plate with a retardation layer can be particularly suitably applied to a curved image display device and / or a bendable or bendable image display device. It should be noted that the total thickness of the polarizing plate with a retardation layer constitutes the polarizing plate with a retardation layer except for an adhesive layer for adhering the polarizing plate with a retardation layer to an external adherend such as a panel or glass. It means the total thickness of all layers (that is, the total thickness of the polarizing plate with a retardation layer is a pressure-sensitive adhesive layer for sticking the polarizing plate with a retardation layer to an adjacent member such as an image display cell and its surface. Does not include the thickness of the release film that can be applied).

The constituent elements of the polarizing plate with retardation layer will be described in more detail below.

B. Polarizing plate B-1. Polarizing Film As described above, the polarizing film 11 has a thickness of 8 μm or less and a unit absorbance at a wavelength of 210 nm of 1.00 or less. The polarizing film used in the present invention has an extremely small unit absorbance at a wavelength of 210 nm as compared with a normal thin polarizing film. This means that the content ratio of iodine ions (having absorption in the ultraviolet region near 210 nm) not forming a complex with PVA in the polarizing film is extremely small. In the polarizing film, iodine is roughly classified into iodine ions having absorption in the ultraviolet region and PVA-iodine complex having absorption in visible light. Among these, it is the PVA-iodine complex that contributes to the polarization characteristics 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 PVA-iodine complex. That is, in a thin polarizing film having a thickness of 8 μm or less, it is possible to improve the optical characteristics by reducing iodine ions. This tendency becomes remarkable especially in a polarizing film having a small thickness and a high iodine concentration in the film. The unit absorbance at a wavelength of 210 nm is preferably 0.80 or less, more preferably 0.60 or less. The lower limit of the unit absorbance at the wavelength of 210 nm can be, for example, 0.20. The unit absorbance is obtained by dividing the orthogonal absorbance A ₂₁₀ obtained by the following formula based on the orthogonal transmittance Tc of the polarizing plate measured when obtaining the polarization degree described later by the thickness. The unit absorbance of the polarizing plate substantially corresponds to the unit absorbance of the polarizing film.
Orthogonal absorbance = log10 (100 / Tc)
The use of a thin polarizing film having such characteristics is one of the features of the present invention. In addition, the polarizing film has a unit absorbance as described above, and the ratio (A ₅₅₀ / A ₂₁₀ ) of the orthogonal absorbance A ₅₅₀ at a wavelength of ₅₅₀ nm and the orthogonal absorbance A ₂₁₀ at a wavelength of 210 nm is preferably 1 or less. It is at least 0.4, more preferably at least 1.8, even more preferably at least 2.0, and particularly preferably at least 2.2. The upper limit of the ratio (A ₅₅₀ / A ₂₁₀ ) may be 3.5, for example. This, in the polarizing film, decreasing the content ratio of iodine ion, PVA-I ₅ having an absorption in the vicinity of 600 nm ^- means that the content ratio of the complex is increased.

The thickness of the polarizing film is preferably 1 μm to 8 μm, more preferably 1 μm to 7 μm, further preferably 2 μm to 5 μm, particularly preferably 2 μm to 4 μm, and particularly preferably 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, more preferably 48.0% or less. On the other hand, the simple substance transmittance is preferably 41.5% or more, more preferably 42.0% or more, and further 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-piece transmittance is typically a Y value measured using an ultraviolet-visible spectrophotometer and subjected to luminosity correction. The polarization degree is typically obtained by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc measured by using an ultraviolet-visible spectrophotometer and subjected to the visibility correction.
Polarization degree (%) = {(Tp-Tc) / (Tp + Tc)} ^1/2 × 100

In one embodiment, the transmittance of a thin polarizing film having a thickness of 8 μm or less is typically obtained by laminating a polarizing film (refractive index of surface: 1.53) and a protective film (refractive index: 1.50). It is measured using an ultraviolet-visible spectrophotometer with the body as the measurement target. Depending on the refractive index of the surface of the polarizing film and / or the refractive index of the surface of the protective film in contact with the air interface, the reflectance at the interface of each layer may change, and as a result, the measured transmittance may change. . Therefore, for example, when using a protective film whose refractive index is not 1.50, the measured value of the transmittance may be corrected according to the refractive index of the surface of the protective film in contact with the air interface. Specifically, the transmittance correction value C is expressed by the following equation 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 transmission axis reflectance when a protective film having a refractive index of 1.50 is used, n ₁ is the refractive index of the protective film used, and T ₁ is the transmittance of the polarizing film. Is. For example, when a substrate having a surface refractive index of 1.53 (such as a cycloolefin film and a film with a hard coat layer) is used as a protective film, the correction amount C is about 0.2%. In this case, by adding 0.2% to the transmittance obtained by the measurement, the transmittance when the protective film having a refractive index of 1.50 is used for the polarizing film having a surface refractive index of 1.53. It can be converted into a rate. According to the calculation based on the above formula, the change amount of 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 is the correction value C. The effect on the value of is limited. 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 and the orthogonal absorbance A ₆₀₀ at a wavelength of 600 nm of 0.7 or more, more preferably 0.75 or more, It is more preferably 0.80 or more, and particularly preferably 0.85 or more. The ratio (A ₄₇₀ / A ₆₀₀ ) is preferably 2.00 or less, more preferably 1.33 or less. When the ratio (A ₄₇₀ / A ₆₀₀ ) is in such a range, the content ratio of the PVA-I3-complex having absorption near 480 nm can be maintained without being significantly reduced. 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 was limited, it was difficult for the prior art to set both the unit absorbance and the ratio (A ₄₇₀ / A ₆₀₀ ) in the desired range. The polarizing film used can have both of these in desired ranges.

Further, the orthogonal b value of the polarizing film is, for example, larger 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 shows the hue when the polarizing film (finally, the polarizing plate with the retardation layer) is arranged in the orthogonal state. The larger the absolute value of this numerical value, the orthogonal hue (black in the image display device). (Indication) means that it looks tint. For example, when the orthogonal b value is as low as −10 or less, the black display looks blue and the display performance is deteriorated. That is, according to the embodiment of the present invention, it is possible to obtain a polarizing plate with a retardation layer that can realize an excellent hue during black display. 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 further preferably 6% by weight or more. The upper limit of iodine concentration may be, for example, 12% by weight. When the iodine concentration is in such a range, the effect of reducing the unit absorbance becomes remarkable. In other words, the above effect is remarkable in the thin polarizing film having such a high iodine concentration.

Any suitable polarizing film can be adopted as the polarizing film. The polarizing film can be typically manufactured by using a laminate of two or more layers.

A specific example of the polarizing film obtained by using the laminated body is a polarizing film obtained by using a laminated body of a resin base material and a PVA-based resin layer formed by coating on the resin base material. A polarizing film obtained by using a laminate of a resin base material and a PVA-based resin layer applied and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying it. A PVA-based resin layer is formed thereon to obtain a laminate of a resin substrate and a PVA-based resin layer; the laminate is stretched and dyed to form the PVA-based resin layer as a polarizing film. obtain. In the present embodiment, the stretching typically includes dipping the laminate in a boric acid aqueous solution and stretching. Further, the stretching may further include optionally stretching the laminate in air at a high temperature (for example, 95 ° C. or higher) before stretching in the aqueous boric acid solution. The obtained resin base material / polarizing film laminate may be used as it is (that is, the resin base material may be used as a protective layer of the polarizing film), or the resin base material is peeled from the resin base material / polarizing film laminate. However, any appropriate protective layer may be laminated and used on the peeled surface depending on the purpose. Details of the method for producing such a polarizing film are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. The entire description of the publication is incorporated herein by reference.

The method for manufacturing a polarizing film is typically a laminate of a polyvinyl alcohol resin layer containing a halide and a polyvinyl alcohol resin on one side of a long thermoplastic resin substrate. And subjecting the laminate to an in-air auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment of shrinking 2% or more in the width direction by heating while conveying in the longitudinal direction in this order. including. This can provide a polarizing film having excellent optical characteristics, having a thickness of 8 μm or less and a unit absorbance at a wavelength of 210 nm of 1.00 or less. That is, by introducing the auxiliary stretching, the crystallinity of PVA can be increased and high optical characteristics can be achieved even when PVA is applied onto the thermoplastic resin. At the same time, by preliminarily enhancing the orientation of PVA, it is possible to prevent problems such as reduction in orientation and dissolution of PVA when immersed in water in the subsequent dyeing step or stretching step, and high optical characteristics. Can be achieved. Furthermore, when the PVA-based resin layer is dipped in a liquid, the disorder of the alignment of the polyvinyl alcohol molecules and the deterioration of the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This can improve the optical characteristics of the polarizing film obtained through a treatment process such as a dyeing treatment and an underwater stretching treatment performed by immersing the laminate in a liquid. Further, the optical characteristics can be improved by shrinking the laminate in the width direction by the dry shrinking treatment.

B-2. Protective Layer The first protective layer 12 and the second protective layer 13 are each formed of any suitable film that can be used as a protective layer of a polarizing film. Specific examples of the material serving as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyimide resins, polyether sulfone resins, and polysulfone resins. , Polystyrene-based, polynorbornene-based, polyolefin-based, (meth) acrylic-based, acetate-based transparent resins and the like. Further, a thermosetting resin such as a (meth) acrylic resin, a urethane resin, a (meth) acrylic urethane resin, an epoxy resin, a silicone resin, or an ultraviolet curable resin can be used. In addition to these, for example, a glassy polymer such as a siloxane polymer may be used. Further, the polymer film described in JP 2001-343529 A (WO 01/37007) can also be used. Examples of the material of this film include a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. Can be used, and examples thereof include a resin composition having an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The polymer film can be, for example, an extruded product of the resin composition. In one embodiment, the protective layer (particularly, the protective layer on the viewing side) includes a TAC resin. By using the TAC resin film as the protective layer, the bending durability can be improved.

The polarizing plate with a retardation layer of the present invention is typically arranged on the viewing side of the image display device as described later, and the first protective layer 12 is typically arranged on the viewing side. Therefore, the first protective layer 12 may be subjected to surface treatment such as hard coat treatment, antireflection treatment, sticking prevention treatment, and antiglare treatment, if necessary. Further / or, if necessary, the first protective layer 12 is processed to improve the visibility when viewed through polarized sunglasses (typically, a (elliptical) circular polarization function is added, (Giving an ultrahigh phase difference) may be applied. By performing such a process, excellent visibility can be realized even when the display screen is viewed through a polarizing lens such as polarized sunglasses. Therefore, the polarizing plate with a retardation layer can be suitably applied to an image display device that 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. When the surface treatment is applied, the thickness of the outer protective layer is the thickness including the thickness of the surface treated layer.

The second protective layer 13 is preferably 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 thickness direction retardation Rth (550) is −10 nm to +10 nm. Say. The second protective layer 13 may be a retardation layer having any appropriate 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. From the viewpoint of reduction in thickness and weight, the second protective layer can be preferably omitted.

B-3. Method for manufacturing polarizing film The polarizing film is, for example, a polyvinyl alcohol resin layer (PVA resin layer) containing a halide and a polyvinyl alcohol resin (PVA resin) on one side of a long thermoplastic resin substrate. To form a laminated body, and the laminated body is subjected to an in-air auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and drying for shrinking 2% or more in the width direction by heating while conveying in the longitudinal direction. The shrinkage treatment and the shrinkage treatment may be performed in this order. 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 dry shrinkage treatment is preferably 2% or more. According to such a manufacturing method, the polarizing film described in the above section B-1 can be obtained. In particular, a laminate including a PVA-based resin layer containing a halide is prepared, and the laminate is stretched in multiple stages including in-air auxiliary stretching and underwater stretching, and the laminated laminate is heated with a heating roll. It is possible to obtain a polarizing film having excellent optical characteristics (typically, single transmittance and unit absorbance at a wavelength of 210 nm).

B-3-1. Preparation of Laminate As a method of preparing a laminate of the thermoplastic resin substrate and the PVA-based resin layer, any suitable method can be adopted. Preferably, a PVA-based resin layer is formed on the thermoplastic resin substrate by applying a coating liquid containing a halide and a PVA-based resin on the surface of the thermoplastic resin substrate and drying the coating liquid. 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 appropriate method can be adopted as the method for applying the application liquid. For example, a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a knife coating method (a comma coating method, etc.) and the like can be mentioned. The coating / drying temperature of the coating liquid is preferably 50 ° C. or higher.

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

Before the PVA-based resin layer is formed, the thermoplastic resin substrate may be subjected to surface treatment (for example, corona treatment), or the easily adhesive layer may be formed on the thermoplastic resin substrate. By performing such a treatment, the adhesion between the thermoplastic resin base material and the PVA-based resin layer can be improved.

B-3-1-1. Thermoplastic resin substrate 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 μm, it may be difficult to form the PVA-based resin layer. If it exceeds 300 μm, it may take a long time for the thermoplastic resin substrate to absorb water in the below-described underwater stretching treatment, and an excessive load may be required for stretching.

The thermoplastic resin base material preferably has a water absorption of 0.2% or more, and more preferably 0.3% or more. The thermoplastic resin base material absorbs water, and the water acts as a plasticizer and can be plasticized. As a result, the stretching stress can be significantly reduced, and stretching can be performed at a high ratio. 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, it is possible to prevent problems such as the dimensional stability of the thermoplastic resin base material being significantly reduced during production, and the appearance of the polarizing film obtained being deteriorated. In addition, it is possible to prevent the base material from breaking during the underwater stretching and the PVA-based resin layer from peeling off from the thermoplastic resin base material. The water absorption of the thermoplastic resin substrate can be adjusted, for example, by introducing a modifying group into the constituent material. The water absorption rate is a value determined according to JIS K7209.

The glass transition temperature (Tg) of the thermoplastic resin base material is preferably 120 ° C. or lower. By using such a thermoplastic resin substrate, it is possible to sufficiently secure the stretchability of the laminate while suppressing the crystallization of the PVA-based resin layer. Further, in consideration of good plasticization of the thermoplastic resin substrate with water and favorable underwater stretching, the temperature is preferably 100 ° C. or lower, and more preferably 90 ° C. or lower. 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 base material, the thermoplastic resin base material may be deformed (for example, unevenness, wrinkles, wrinkles, etc.) when the coating liquid containing the PVA-based resin is applied and dried. It is possible to satisfactorily produce a laminated body by preventing the above problems. Moreover, the PVA-based resin layer can be stretched well at a suitable temperature (for example, about 60 ° C.). The glass transition temperature of the thermoplastic resin substrate can be adjusted, for example, by introducing a modifying group into the constituent material and heating it with a crystallization material. The glass transition temperature (Tg) is a value determined according to JIS K7121.

Any suitable thermoplastic resin can be adopted as the constituent material of the thermoplastic resin base material. Examples of the thermoplastic resin include ester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins such as norbornene-based resins, olefin-based resins such as polypropylene, polyamide-based resins, polycarbonate-based resins, and copolymer resins thereof. Is mentioned. Among these, norbornene-based resins and amorphous polyethylene terephthalate-based resins are preferable.

In one embodiment, an amorphous (non-crystallized) polyethylene terephthalate resin is preferably used. Among them, an amorphous (hard to crystallize) polyethylene terephthalate 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 a dicarboxylic acid, and a copolymer further containing cyclohexanedimethanol or diethylene glycol as a glycol.

In a preferred embodiment, the thermoplastic resin base material is composed of a polyethylene terephthalate resin having an isophthalic acid unit. This is because such a thermoplastic resin substrate has extremely excellent stretchability and can suppress crystallization during stretching. It is considered that this is because the main chain is largely bent by introducing the isophthalic acid unit. The polyethylene terephthalate resin has a terephthalic acid unit and an ethylene glycol unit. The content ratio of the isophthalic acid unit is preferably 0.1 mol% or more, more preferably 1.0 mol% or more based on the total of all repeating units. This is because a thermoplastic resin substrate having extremely excellent stretchability can be obtained. On the other hand, the content ratio of the isophthalic acid unit is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total of all repeating units. By setting such a content ratio, the crystallinity can be favorably increased in the drying shrinkage treatment described below.

The thermoplastic resin substrate may be stretched in advance (before forming the PVA-based resin layer). In one embodiment, the elongated thermoplastic resin substrate is stretched in the lateral direction. The lateral direction is preferably a direction orthogonal to the stretching direction of the laminate described below. In addition, in this specification, the term "orthogonal" includes the case of being substantially orthogonal. Here, “substantially orthogonal” includes the case of 90 ° ± 5.0 °, preferably 90 ° ± 3.0 °, and more preferably 90 ° ± 1.0 °.

The stretching temperature of the thermoplastic resin substrate is preferably Tg-10 ° C to Tg + 50 ° C with respect to the glass transition temperature (Tg). The stretch ratio of the thermoplastic resin substrate is preferably 1.5 to 3.0 times.

Any appropriate method can be adopted as a method for stretching the thermoplastic resin substrate. Specifically, it may be fixed-end stretching or free-end stretching. The stretching method may be dry or wet. Stretching of the thermoplastic resin substrate may be performed in one stage or in multiple stages. When performing in multiple stages, the above-mentioned draw ratio is a product of the draw ratio of each stage.

B-3-1-2. Coating liquid The coating liquid contains a halide and a PVA-based resin as described above. The coating liquid is typically a solution prepared by dissolving the halide and the PVA resin in a solvent. Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These can be used alone or in combination of two or more. Of these, water is preferable. The PVA-based resin concentration of the solution is preferably 3 to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, it is possible to form a uniform coating film in close contact with the thermoplastic resin substrate. The content of the halide in the coating liquid is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin.

Additives may be added to the coating liquid. Examples of the additive include a plasticizer and a surfactant. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. Examples of the surfactant include nonionic surfactants. 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 can be adopted as the PVA-based resin. Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer can be obtained by saponifying an 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%. . The degree of saponification can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a saponification degree, a polarizing film having excellent durability can be obtained. If the degree of saponification is too high, gelation may occur.

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

Any suitable halide can be adopted as the above-mentioned halide. Examples include iodide and sodium chloride. Examples of iodides include potassium iodide, sodium iodide, and lithium iodide. Among these, potassium iodide is preferable.

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

Generally, when the PVA-based resin layer is stretched, the orientation of the polyvinyl alcohol molecules in the PVA-based resin increases, but when the stretched PVA-based resin layer is immersed in a liquid containing water, the polyvinyl alcohol molecules The orientation may be disturbed and the orientation may be deteriorated. In particular, when a laminate of a thermoplastic resin base material and a PVA-based resin layer is stretched in boric acid water, the laminate is heated in boric acid water at a relatively high temperature in order to stabilize the stretching of the thermoplastic resin base material. In the case of stretching, the above-mentioned tendency of decreasing the degree of orientation is remarkable. For example, while stretching of a PVA film alone in boric acid water is generally performed at 60 ° C., stretching of a laminate of A-PET (thermoplastic resin base material) and PVA-based resin layer is performed. It is carried out at a high temperature of around 70 ° C. In this case, the orientation of PVA in the initial stage of stretching may be lowered in a stage before being raised by the underwater stretching. On the other hand, by forming a laminate of a PVA-based resin layer containing a halide and a thermoplastic resin substrate, and stretching the laminate at high temperature in air (auxiliary stretching) before stretching in boric acid water. The crystallization of the PVA-based resin in the PVA-based resin layer of the laminate after the auxiliary stretching can be promoted. As a result, when the PVA-based resin layer is immersed in the liquid, the disorder of the alignment of the polyvinyl alcohol molecules and the deterioration of the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This can improve the optical characteristics of the polarizing film obtained through a treatment process such as a dyeing treatment and an underwater stretching treatment performed by immersing the laminate in a liquid.

B-3-2. In-air auxiliary stretching treatment In order to obtain particularly high optical characteristics, a two-stage stretching method is selected in which dry stretching (auxiliary stretching) and boric acid in-water stretching are combined. By introducing auxiliary stretching like two-stage stretching, it is possible to perform stretching while suppressing crystallization of the thermoplastic resin substrate, and excessive crystallization of the thermoplastic resin substrate in subsequent boric acid underwater stretching. Thereby, the problem that the stretchability is lowered can be solved, and the laminate can be stretched at a higher ratio. Furthermore, in the case of applying the PVA-based resin on the thermoplastic resin base material, in order to suppress the influence of the glass transition temperature of the thermoplastic resin base material, compared with the case of applying the PVA-based resin on a normal metal drum. Therefore, it is necessary to lower the coating temperature, and as a result, the crystallization of the PVA-based resin becomes relatively low, which may cause a problem that sufficient optical characteristics cannot be obtained. On the other hand, by introducing the auxiliary stretching, the crystallinity of the PVA-based resin can be increased even when the PVA-based resin is applied on the thermoplastic resin, and high optical characteristics can be achieved. Become. Further, at the same time, by preliminarily enhancing the orientation of the PVA-based resin, it is possible to prevent problems such as deterioration of the orientation of the PVA-based resin and dissolution when the PVA-based resin is immersed in water in the subsequent dyeing step or stretching step. It becomes possible to achieve high optical characteristics.

The stretching method for the in-air auxiliary stretching may be fixed-end stretching (for example, a stretching method using a tenter stretching machine) or free-end stretching (for example, a uniaxial stretching method in which a laminate is passed between rolls having different peripheral speeds). Although good, free-end stretching can be positively adopted in order to obtain high optical characteristics. In one embodiment, the in-air stretching treatment includes a heating roll stretching step of stretching the laminate by the difference in peripheral speed between the heating rolls while conveying the laminate in the longitudinal direction. The in-air stretching treatment typically includes a zone stretching step and a heating roll stretching step. The order of the zone stretching step and the heating roll stretching step is not limited, and the zone stretching step may be performed first or the heating roll stretching step may be performed first. The zone stretching step may be omitted. In one embodiment, the zone stretching step and the heated roll stretching step are performed in this order. Further, in another embodiment, in the tenter stretching machine, stretching is performed by gripping the film end portion and widening the distance between the tenter in the flow direction (expansion of the distance between the tenter is the stretching ratio). At this time, the distance of the tenter in the width direction (direction perpendicular to the flow direction) is set to be arbitrarily close. Preferably, it can be set so as to be closer to the free end stretching with respect to the stretching ratio in the machine direction. In the case of free end drawing, the shrinkage ratio in the width direction is calculated by (1/1 / drawing ratio) ^1/2 .

Assisted stretching in the air may be performed in one stage or in multiple stages. When performing in multiple stages, the draw ratio is the product of the draw ratios in each stage. The stretching direction in the in-air auxiliary stretching is preferably substantially the same as the stretching direction in the underwater stretching.

The draw ratio in the in-air auxiliary drawing is preferably 2.0 to 3.5 times. The maximum draw ratio when the in-air auxiliary drawing and the underwater drawing are combined is preferably 5.0 times or more, more preferably 5.5 times or more, and further preferably 6.0 times, with respect to the original length of the laminate. That is all. In the present specification, the "maximum stretch ratio" means a stretch ratio immediately before the laminated body breaks, and separately confirms the stretch ratio at which the laminated body breaks, and means a value 0.2 lower than the value.

The stretching temperature of the in-air 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 the glass transition temperature (Tg) or higher of the thermoplastic resin substrate, more preferably the glass transition temperature (Tg) + 10 ° C. or higher of the thermoplastic resin substrate, and particularly preferably Tg + 15 ° C. or higher. On the other hand, the upper limit of the stretching temperature is preferably 170 ° C. By stretching at such a temperature, it is possible to suppress rapid crystallization of the PVA-based resin and suppress defects due to the crystallization (for example, to prevent orientation of the PVA-based resin layer due to stretching). it can. The crystallization index of the PVA-based resin after the in-air auxiliary 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, 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 ).
However,
I _C: intensity _{I R} of 1141cm ^-1 when measured by the incident measurement light: the intensity of 1440cm ^-1 when measured by the incident measurement light.

B-3-3. Insolubilization treatment If necessary, an insolubilization treatment is performed after the in-air auxiliary stretching treatment and before the underwater stretching treatment or the dyeing treatment. The insolubilization treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By applying the insolubilization treatment, it is possible to impart water resistance to the PVA-based resin layer and prevent the orientation of PVA from being lowered when immersed in water. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilizing bath (boric acid aqueous solution) is preferably 20 ° C to 50 ° C.

B-3-4. Dyeing Treatment The above dyeing treatment is typically performed by dyeing the PVA-based resin layer with a dichroic material (typically iodine). Specifically, it is performed by adsorbing iodine on the PVA resin layer. Examples of the adsorption method include a method of immersing the PVA-based resin layer (laminate) in a dyeing solution containing iodine, a method of applying the dyeing solution to the PVA-based resin layer, and a method of applying the dyeing solution to the PVA-based resin layer. Examples include a method of spraying. A preferred method is to immerse the laminate in a dyeing solution (dyeing bath). This is because iodine can be favorably adsorbed.

The dye solution is preferably an iodine aqueous solution. The iodine content is preferably 0.05 to 0.5 parts by weight with respect to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add iodide to the aqueous iodine 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, and titanium iodide. Etc. Among these, potassium iodide is preferable. The content of iodide is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 5 parts by weight, based on 100 parts by weight of water. The temperature of the dyeing solution during dyeing is preferably 20 ° C. to 50 ° C. in order to suppress dissolution of the PVA-based resin. When the PVA-based resin layer is immersed in the dyeing solution, the immersion time is preferably 5 seconds to 5 minutes, more preferably 30 seconds to 90 seconds in order to secure the transmittance of the PVA-based resin layer.

The dyeing conditions (concentration, liquid temperature, immersion time) can be set so that the single transmittance of the finally obtained polarizing film and the unit absorbance at a wavelength of 210 nm have desired values. As such a dyeing condition, preferably, an iodine aqueous solution is used as the dyeing solution, and the ratio of the contents of iodine and potassium iodide in the iodine aqueous 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. As a result, a polarizing film having the above optical characteristics can be obtained.

When the dyeing treatment is continuously performed after the treatment of dipping the laminate in a treatment bath containing boric acid (typically, the insolubilization treatment), the boric acid contained in the treatment bath is mixed in the dyeing bath. The concentration of boric acid in the dyeing bath may change with time, resulting in unstable dyeability. In order to suppress the destabilization of the dyeability as described above, the upper limit of the boric acid concentration in the dyeing bath is preferably 4 parts by weight, more preferably 2 parts by weight, relative to 100 parts by weight of water. Adjusted. On the other hand, the lower limit of the concentration of boric acid in the dyeing bath is preferably 0.1 part by weight, more preferably 0.2 part by weight, still more preferably 0.5 part by weight, relative to 100 parts by weight of water. Is. In one embodiment, the dyeing process is performed using a dyeing bath in which boric acid is preliminarily blended. This can reduce the rate of change in boric acid concentration when boric acid in the treatment bath is mixed in the dyeing bath. The amount of boric acid blended in the dyeing bath in advance (that is, the content of boric acid not derived from the treatment bath) is preferably 0.1 part by weight to 2 parts by weight with respect to 100 parts by weight of water. , And more preferably 0.5 to 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 cross-linking treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing the cross-linking treatment, it is possible to impart water resistance to the PVA-based resin layer and prevent the PVA from being lowered in orientation when it is immersed in high-temperature water in the subsequent underwater stretching. The concentration of the aqueous boric acid solution is preferably 1 part by weight to 5 parts by weight with respect to 100 parts by weight of water. Further, when the crosslinking treatment is performed after the dyeing treatment, it is preferable to further add iodide. By blending iodide, elution of iodine adsorbed on the PVA-based resin layer can be suppressed. The iodide content is preferably 1 to 5 parts by weight with respect to 100 parts by weight of water. Specific examples of 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 crystallized. It is possible to stretch at a high magnification while suppressing the above. As a result, a polarizing film having excellent optical properties can be manufactured.

Any appropriate method can be adopted as the stretching method of the laminate. Specifically, it may be fixed-end stretching or free-end stretching (for example, a method of uniaxially stretching by passing a laminate between rolls having different peripheral speeds). Preferably, free end stretching is selected. Stretching of the laminate may be performed in one stage or in multiple stages. When performing in multiple stages, the stretching ratio (maximum stretching ratio) of the laminate to be described later is the product of the stretching ratios in each stage.

The underwater stretching is preferably performed by immersing the laminate in a boric acid aqueous solution (boric acid underwater stretching). By using an aqueous boric acid solution as the stretching bath, the PVA-based resin layer can be provided with rigidity that can withstand the tension applied during stretching and water resistance that does not dissolve in water. Specifically, boric acid can generate a tetrahydroxyborate anion in an aqueous solution to crosslink with a PVA-based resin by hydrogen bond. As a result, the PVA-based resin layer can be imparted with rigidity and water resistance, can be favorably stretched, and a polarizing film having excellent optical characteristics can be manufactured.

The boric acid aqueous solution is preferably obtained by dissolving boric acid and / or borate in water as a solvent. The boric acid concentration is preferably 1 part by weight to 10 parts by weight, more preferably 2.5 parts by weight to 6 parts by weight, particularly preferably 3 parts by weight to 5 parts by weight, relative to 100 parts by weight of water. Is. By setting the concentration of boric acid to 1 part by weight or more, dissolution of the PVA-based resin layer can be effectively suppressed, and a polarizing film with higher characteristics 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 added to the above stretching bath (boric acid aqueous solution). By blending iodide, elution of iodine adsorbed on the PVA-based resin layer can be suppressed. Specific examples of iodide are as described above. The concentration of iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight with respect to 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. At such a temperature, the PVA-based resin layer can be stretched at a high magnification while suppressing the dissolution. 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, if the stretching temperature is lower than 40 ° C., it may not be possible to stretch well even if the plasticization of the thermoplastic resin substrate by water is taken into consideration. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin layer, and there is a possibility that excellent optical characteristics may not be obtained. The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.

Draw ratio by underwater drawing is preferably 1.5 times or more, more preferably 3.0 times or more. The total draw ratio of the laminated body is preferably 5.0 times or more, more preferably 5.5 times or more, with respect to the original length of the laminated body. By achieving such a high draw ratio, a polarizing film having extremely excellent optical characteristics can be manufactured. Such a high draw ratio can be achieved by adopting an underwater drawing method (boric acid underwater drawing).

B-3-7. Drying Shrinkage Treatment The drying shrinkage treatment may be performed by zone heating performed by heating the entire zone, or may be performed by heating the transport roll (using a so-called heating roll) (heating roll drying method). Both are preferably used. By drying using a heating roll, it is possible to efficiently suppress the curling of the laminate by heating and to produce a polarizing film having an excellent appearance. Specifically, by drying the laminate along a heating roll, the crystallization of the thermoplastic resin substrate can be efficiently promoted to increase the crystallinity, which is relatively low. Even at the drying temperature, the crystallinity of the thermoplastic resin substrate can be satisfactorily increased. As a result, the rigidity of the thermoplastic resin base material increases, and the thermoplastic resin base material can withstand the shrinkage of the PVA-based resin layer due to drying, and curling is suppressed. Further, by using the heating roll, the laminate can be dried while being kept flat, so that not only curling but also wrinkling can be suppressed. At this time, the laminated body can be improved in optical characteristics by shrinking in the width direction by a drying shrinkage treatment. This is because the orientation of PVA and the PVA / iodine complex can be effectively enhanced. The shrinkage ratio in the width direction of the laminate by the dry shrinkage treatment is preferably 1% to 10%, more preferably 2% to 8%, and particularly preferably 4% to 6%. By using the heating roll, the laminate can be continuously contracted in the width direction while being conveyed, and high productivity can be realized.

FIG. 3 is a schematic diagram showing an example of the drying shrinkage treatment. In the drying shrinkage treatment, the laminate 200 is dried while being transported by the transport rolls R1 to R6 heated to a predetermined temperature and the guide rolls G1 to G4. In the illustrated example, the transport 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. However, for example, one surface of the laminate 200 (for example, thermoplastic The transport rolls R1 to R6 may be arranged so that only the resin substrate surface) is continuously heated.

The drying conditions can be controlled by adjusting the heating temperature of the transfer rolls (heating roll temperature), the number of heating rolls, the contact time with the heating rolls, and the like. 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 of the thermoplastic resin can be favorably increased, curling can be favorably suppressed, and an optical laminate having extremely excellent durability can be manufactured. The temperature of the heating roll can be measured with a contact thermometer. In the illustrated example, six transport rolls are provided, but there is no particular limitation as long as there are multiple transport rolls. The number of transport rolls is usually 2 to 40, preferably 4 to 30. 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 further preferably 1 to 10 seconds.

The heating roll may be provided in a heating furnace (for example, an oven) or may be provided in a normal production line (under room temperature environment). Preferably, it is provided in a heating furnace equipped with a blowing means. By using the drying with the heating roll and the hot air drying together, a sharp temperature change between the heating rolls can be suppressed and the shrinkage in the width direction can be easily controlled. The temperature of hot air drying is preferably 30 ° C to 100 ° C. The hot air drying time is preferably 1 to 300 seconds. The wind speed of the hot air is preferably about 10 m / s to 30 m / s. The wind speed is the wind speed in the heating furnace, and can be measured by a mini vane type digital anemometer.

B-3-8. Other Treatments Preferably, a washing treatment is performed after the underwater stretching treatment and before the drying shrinkage treatment. The cleaning 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 appropriate optical property and / or mechanical property depending on the purpose. The first retardation layer 20 typically has a slow axis. In one embodiment, the angle θ formed by 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, preferably 42 ° to 48 °. And more preferably about 45 °. If the angle θ is in such a range, by using the λ / 4 plate as the first retardation layer as described later, very excellent circular polarization characteristics (as a result, very excellent antireflection characteristics) A polarizing plate with a retardation layer having is obtained.

The first retardation layer preferably has a refractive index characteristic of nx> ny ≧ nz. The first retardation layer is typically provided to impart antireflection characteristics to the polarizing plate, and can function as a λ / 4 plate in one embodiment. In this case, the in-plane retardation Re (550) of the 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. Here, “ny = nz” includes not only the case where ny and nz are completely equal but also the case where they are substantially equal. Therefore, ny <nz may be satisfied as long as the effect of the present invention is not impaired.

The Nz coefficient of the first retardation layer is preferably 0.9 to 3, more preferably 0.9 to 2.5, further preferably 0.9 to 1.5, particularly preferably 0.9 to 1. It is 3. By satisfying such a relationship, a very excellent reflective hue can be achieved when the obtained polarizing plate with a retardation layer is used in an image display device.

The first retardation layer may exhibit an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, and a positive wavelength dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. It may be shown, or may exhibit a flat wavelength dispersion characteristic in which the phase difference value hardly changes even with the wavelength of the measurement light. 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, it is possible to realize a very excellent antireflection characteristic.

The absolute value of the photoelastic coefficient of the first retardation layer is preferably 2 × 10 ⁻¹¹ m ² / N or less, more preferably 2.0 × 10 ⁻¹³ m ² / N to 1.5 × 10 ^−11. m ² / N, more preferably from ^{^{^{1.0 × 10 -12 m 2 /N~1.2×10 -11}}} m 2 / N resin. When the absolute value of the photoelastic coefficient is in such a range, it is difficult for the phase difference to change when contraction stress occurs during heating. As a result, heat unevenness of the obtained image display device can be favorably prevented.

The first retardation layer is typically composed of a stretched film of a resin film. In one embodiment, the thickness of the first retardation layer is preferably 70 μm or less, more preferably 45 μm to 60 μm. When the thickness of the first retardation layer is within such a range, curl during heating can be suppressed well, and curl during bonding can be adjusted well. Further, as described later, in the embodiment in which the first retardation layer is composed of a polycarbonate resin film, the thickness of the first retardation layer is preferably 40 μm or less, more preferably 10 μm to 40 μm. And more preferably 20 μm to 30 μm. When the first retardation layer is formed of the polycarbonate resin film having such a thickness, curling can be suppressed and the bending durability and the reflection hue can be improved.

The first retardation layer 20 may be composed of any appropriate resin film that can satisfy the above characteristics. Typical 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, polyamide resins. , A polyimide resin, a polyether resin, a polystyrene resin, and an acrylic resin. These resins may be used alone or in combination (for example, blending or copolymerization). When the first retardation layer is composed of a resin film exhibiting reverse dispersion wavelength characteristics, a polycarbonate resin or a polyester carbonate resin (hereinafter sometimes simply referred to as a polycarbonate resin) can be preferably used.

As the polycarbonate resin, any appropriate polycarbonate resin can be used as long as the effects of the present invention can be obtained. For example, a polycarbonate-based resin is 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 polyethylene glycol, and an alkylene. A structural unit derived from at least one dihydroxy compound selected from the group consisting of glycols or spiroglycols. Preferably, the polycarbonate-based resin is 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 an alicyclic dimethanol and / or di, tri or polyethylene glycol. And 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 a di-, tri-, or polyethylene glycol. . The polycarbonate-based resin may include a structural unit derived from another dihydroxy compound, if necessary. Details of the polycarbonate-based resin that can be preferably used in the present invention are described in, for example, JP-A-2014-10291, 2014-26266, JP-A-2015-212816, and JP-A-2015-212817. , Japanese Patent Application Laid-Open No. 2015-212818, which description is incorporated herein by reference.

The glass transition temperature of the polycarbonate resin is preferably 110 ° C. or higher and 150 ° C. or lower, and more preferably 120 ° C. or higher and 140 ° C. or lower. If the glass transition temperature is excessively low, the heat resistance tends to be poor, dimensional change may occur after film formation, and the image quality of the obtained organic EL panel may be deteriorated. If the glass transition temperature is excessively high, the molding stability during film molding may be deteriorated, and the transparency of the film may be impaired. The glass transition temperature is calculated according to JIS K 7121 (1987).

The molecular weight of the polycarbonate resin can be represented by reduced viscosity. The reduced viscosity is measured using a Ubbelohde viscosity tube at a temperature of 20.0 ° C. ± 0.1 ° C. by precisely adjusting the polycarbonate concentration to 0.6 g / dL using methylene chloride as a solvent. The lower limit of the reduced viscosity is usually preferably 0.30 dL / g, more preferably 0.35 dL / g or more. The upper limit of the reduced viscosity is usually preferably 1.20 dL / g, more preferably 1.00 dL / g, further preferably 0.80 dL / g. If the reduced viscosity is smaller than the lower limit, there may occur a problem that the mechanical strength of the molded product becomes small. On the other hand, when the reduced viscosity is higher than the upper limit value, the fluidity at the time of molding may be lowered, and the productivity and the moldability may be lowered.

A commercially available film may be used as the polycarbonate resin film. Specific examples of commercially available products include Teijin's product names “Pure Ace WR-S”, “Pure Ace WR-W”, “Pure Ace WR-M”, and Nitto Denko's product name “NRF”. To be

The first retardation layer 20 is obtained, for example, by stretching a film formed of the above polycarbonate resin. Any appropriate molding method can be adopted as a method of forming a film from the polycarbonate-based resin. Specific examples include compression molding method, transfer molding method, injection molding method, extrusion molding method, blow molding method, powder molding method, FRP molding method, cast coating method (for example, casting method), calender molding method, hot press. Law etc. are mentioned. An extrusion molding method or a cast coating method is preferable. This is because the smoothness of the obtained film can be improved and good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition and type of the resin used, the characteristics desired for the retardation layer, and the like. As described above, since many film products of the polycarbonate-based resin are commercially available, the commercially available film may be directly subjected to the stretching treatment.

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 characteristics, stretching conditions described below, and the like. The thickness is preferably 50 μm to 300 μm.

Any appropriate stretching method and stretching conditions (for example, stretching temperature, stretching ratio, stretching direction) can be adopted for the above stretching. Specifically, various stretching methods such as free-end stretching, fixed-end stretching, free-end contraction, and fixed-end contraction can be used alone or simultaneously or sequentially. The stretching direction can also be performed in various directions and dimensions such as the length direction, the width direction, the thickness direction, and the oblique direction. The stretching temperature is preferably Tg-30 ° C. to Tg + 60 ° C., more preferably Tg-10 ° C. to Tg + 50 ° C., with respect to the glass transition temperature (Tg) of the resin film.

By appropriately selecting the stretching method and stretching conditions, it is possible to obtain a retardation film having the desired optical characteristics (eg, refractive index characteristics, in-plane retardation, Nz coefficient).

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

In another embodiment, the retardation film can be produced by continuously stretching a long resin film in the direction of the angle θ with respect to the longitudinal direction. By adopting oblique stretching, a long stretched film having an orientation angle of θ with respect to the longitudinal direction of the film (a slow axis in the direction of angle θ) can be obtained. Roll-to-roll is possible, and the manufacturing process can be simplified. The angle θ may be an angle formed by the absorption axis of the polarizing film and the slow axis of the retardation layer in the polarizing plate with the retardation layer. The angle θ is, as described above, preferably 40 ° to 50 °, more preferably 42 ° to 48 °, and further preferably about 45 °.

As a stretching machine used for oblique stretching, for example, a tenter type stretching machine capable of applying a feeding force or a pulling force or a pulling force at different speeds in the lateral and / or longitudinal directions can be mentioned. Examples of the tenter type stretching machine include a horizontal uniaxial stretching machine and a simultaneous biaxial stretching machine, but any appropriate stretching machine may be used as long as a long resin film can be continuously stretched obliquely.

By appropriately controlling the left and right speeds in the stretching machine, respectively, the retardation layer having the desired in-plane retardation and having a slow axis in the desired direction (substantially long Phase-difference film) can be obtained.

The stretching temperature of the above-mentioned 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 stretching 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, the first retardation layer having suitable properties in the present invention can be obtained. In addition, Tg is a glass transition temperature of the constituent material of the film.

D. Second Retardation Layer As described above, the second retardation layer may be a so-called positive C plate whose refractive index characteristics show a relationship of nz> nx = ny. By using the positive C plate as the second retardation layer, it is possible to favorably prevent reflection in an oblique direction, and it is possible to widen the viewing angle of the antireflection function. 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, further preferably −90 nm to −200 nm, particularly preferably -100 nm to -180 nm. Here, “nx = ny” includes not only the case where nx and ny are exactly 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 appropriate material. The second retardation layer preferably comprises a film containing a liquid crystal material fixed in homeotropic alignment. 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 method of forming the liquid crystal compound and the retardation layer include the liquid crystal compound and the method of forming the retardation layer described in JP-A-2002-333642, [0020] to [0028]. 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 further preferably 0.5 μm to 5 μm.

E. Conductive Layer or Isotropic Substrate with Conductive Layer The conductive layer is formed by any appropriate film formation method (eg, vacuum deposition method, sputtering method, CVD method, ion plating method, spray method, etc.). It may be formed by depositing a metal oxide film thereon. Examples of the metal oxide include indium oxide, tin oxide, zinc oxide, indium-tin complex oxide, tin-antimony complex oxide, zinc-aluminum complex oxide, and indium-zinc complex oxide. Of these, indium-tin composite oxide (ITO) is preferable.

When the conductive layer contains a metal oxide, the thickness of the conductive layer is preferably 50 nm or less, more preferably 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 above-mentioned base material to the first retardation layer (or the second retardation layer, if present), and the conductive layer alone may serve as the constituent layer of the polarizing plate with the retardation layer. Of course, it may be laminated on the first retardation layer (or the second retardation layer, if present) as a laminate with the substrate (substrate with conductive layer). Preferably, the above-mentioned substrate is optically isotropic, so that the conductive layer can be used as a isotropic substrate with a conductive layer in a polarizing plate with a retardation layer.

As the optically isotropic substrate (isotropic substrate), any suitable isotropic substrate can be adopted. Examples of the material forming the isotropic substrate include, for example, a material having a resin having no conjugated system such as norbornene-based resin or olefin-based resin as a main skeleton, and a cyclic structure such as a lactone ring or a glutarimide ring of an acrylic resin. Materials included in the main chain are included. When such a material is used, it is possible to suppress the development of retardation due to the orientation of the molecular chains when forming the isotropic substrate. The thickness of the isotropic substrate is preferably 50 μm or less, 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 required. By patterning, conductive parts and insulating parts can be formed. As a result, electrodes can be formed. The electrodes may function as touch sensor electrodes that sense a touch on the touch panel. Any appropriate method can be adopted as the 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 described in the above items A to E can be applied to an image display device. Therefore, the present invention includes an image display device using such a polarizing plate with a retardation layer. Typical examples of the image display device include a liquid crystal display device and an electroluminescence (EL) display device (for example, an organic EL display device and an inorganic EL display device). The image display device according to the embodiment of the present invention includes the polarizing plate with a retardation layer described in the above items A to E on the viewing side. The polarizing plate with a retardation layer is laminated such that the retardation layer is on the image display cell (for example, liquid crystal cell, organic EL cell, inorganic EL cell) side (the polarizing film is on the viewing side). In one embodiment, the image display device has a curved shape (substantially a curved display screen) and / or is bendable or foldable. In such an image display device, the effect of the polarizing plate with a retardation layer of the present invention becomes remarkable.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples. The measuring method of each characteristic is as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight.
(1) Thickness The thickness of 10 μm or less was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., 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 cross absorbance The single transmittances of the polarizing plates (protective film / polarizing film) of Examples and Comparative Examples were measured by using an ultraviolet-visible spectrophotometer (V-7100 manufactured by JASCO Corporation). Ts, parallel transmittance Tp, and orthogonal transmittance Tc were set as Ts, Tp, and Tc of the polarizing film, respectively. These Ts, Tp and Tc are Y values measured by the 2 degree visual field (C light source) of JIS Z8701 and subjected to the luminosity correction. The refractive index of the protective film was 1.50, and the refractive index of the surface of the polarizing film opposite to the protective film was 1.53.
The orthogonal absorbance A ₂₁₀ was determined from the orthogonal transmittance Tc ₂₁₀ measured at a measurement wavelength of 210 nm using UV-3150 manufactured by Shimadzu Corporation according to the following formula, and divided by the thickness to obtain a unit absorbance. Further, an orthogonal absorbance _{A 470} from the perpendicular transmittance _{Tc 470} for measuring wavelength 470 nm, and, an orthogonal absorbance _{A 600} from the perpendicular transmittance _{Tc 600} for measuring wavelength 600 nm, respectively determined using a Nippon Bunko V-7100.
Orthogonal absorbance = log10 (100 / Tc)
For A ₄₇₀ and A ₆₀₀ , the same measurement can be performed using LPF-200 manufactured by Otsuka Electronics Co., Ltd.
(3) Iodine Concentration Regarding the polarizing films obtained in Examples and Comparative Examples, fluorescent X-ray intensity (measurement diameter: ψ10 mm, manufactured by Rigaku Corporation, trade name “ZSX-PRIMUS II”) was used. kcps) was measured. The iodine concentration (% by weight) was determined from the obtained fluorescent X-ray intensity and thickness using the following formula.
(Iodine concentration) = 20.5 × (fluorescent X-ray intensity) / (film thickness)
The coefficient for calculating the concentration differs depending on the measuring device, but the coefficient can be obtained using an appropriate calibration curve. In this example, a plurality of samples were prepared by adding KI (I: K = 1: 1 (molar ratio)) to PVA at an arbitrary value, and the samples were measured to obtain a calibration curve.
(4) Orthogonal b value The polarizing plates used in Examples and Comparative Examples were measured using an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, product name "V7100"), and the hue in the crossed Nicols state was obtained. . It is shown that the lower the orthogonal b value is (the negative value is and the larger the absolute value is), the more the hue is blue instead of neutral.
(5) Warpage The polarizing plate with a retardation layer obtained in each of Examples and Comparative Examples was cut out into a size of 110 mm × 60 mm. At this time, the polarizing film was cut out so that the absorption axis direction was the long side direction. The cut out polarizing plate with a retardation layer was attached to a glass plate of 120 mm × 70 mm size and 0.2 mm thickness via an adhesive to give a test sample. The test sample was placed in a heating oven maintained at 85 ° C. for 24 hours, and the amount of warp after taking out was measured. When the test sample was allowed to stand on a flat surface with the glass plate facing down, the height of the highest portion from the flat surface was defined as the amount of warpage.
(6) Bending durability The polarizing plates with retardation layers obtained in Examples and Comparative Examples were cut into a size of 50 mm x 100 mm. At this time, the polarizing film was cut out so that the absorption axis direction was the short side direction. Using a folding tester with a constant temperature and constant humidity chamber (CL09 type-D01 manufactured by YUASA), the cut out polarizing plate with a retardation layer was subjected to a bending test under the condition of 20 ° C. and 50% RH. Specifically, the polarizing plate with a retardation layer, so that the retardation layer side is the outer side, repeatedly bent in a direction parallel to the absorption axis direction, such as cracks that cause display defects, peeling or film breakage, etc. The number of times of bending before occurrence was measured and evaluated according to the following criteria (bending diameter: 2 mmφ).
<Evaluation criteria>
Less than 10,000 times: Poor 10,000 times or more and less than 30,000 times: Good 30,000 times or more: Excellent (7) Front reflection hue The polarizing plates with retardation layers obtained in Examples and Comparative Examples have no ultraviolet absorption function. Reflector using acrylic adhesive (trade name "DMS-X42" manufactured by Toray Films Co., Ltd .; reflectance 86%, reflection hue without polarizing plate a ^* =-0.22, b ^* = 0.32) A measurement sample was prepared by pasting on top. At this time, the polarizing plate with a retardation layer was attached such that the retardation layer side faced the reflection plate. The measurement sample was measured by the SCE method using a spectrocolorimeter (CM-2600d manufactured by Konica Minolta), and the values of a ^* and b ^* were substituted into √ (a ^{* 2} + b ^{* 2} ). , The front reflection hue was determined.
(8) Elastic Modulus The film to be measured is formed into a tensile test dumbbell having a parallel part width of 10 mm and a length of 40 mm based on JIS K6734: 2000, and a tensile test is performed according to JIS K7161: 1994 to determine the tensile elastic modulus. I asked. Here, the length direction usually coincides with the stretching direction of the polarizing film.

[Example 1]
1. Preparation of Polarizing Film As the thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) having a long shape, a water absorption of 0.75% and a Tg of about 75 ° C. was used. Corona treatment was applied to one surface 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 "Gosephimmer Z410") in a ratio of 9: 1 100 weight of PVA-based resin To 13 parts by weight, 13 parts by weight of potassium iodide was added and dissolved in water to prepare a PVA aqueous 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, and a laminate was prepared.
The obtained laminated body was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130 ° C. (in-air auxiliary stretching treatment).
Next, the laminated body was immersed in an insolubilizing bath having a liquid temperature of 40 ° C. (boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Then, a dyeing bath having a liquid temperature of 30 ° C. (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1: 7 with respect to 100 parts by weight of water) was added to the finally obtained polarizing film. Immersion was carried out for 60 seconds while adjusting the concentration so that the simple substance transmittance (Ts) and the unit absorbance at a wavelength of 210 nm were desired values (dyeing treatment).
Then, it was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40 ° C. (boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water). (Crosslinking treatment).
Then, while the laminate was immersed in an aqueous boric acid solution (boric acid concentration 4.0% by weight) having a liquid temperature of 70 ° C., the total draw ratio was 5.5 in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds. Uniaxial stretching was performed so as to double the length (underwater stretching treatment).
After that, the laminate was immersed in a cleaning bath having a liquid temperature of 20 ° C. (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
Then, while being dried in an oven kept at 90 ° C., it was brought into contact with a SUS heating roll whose surface temperature was kept at 75 ° C. for about 2 seconds (dry shrinkage treatment). The shrinkage ratio in the width direction of the laminate due to the dry shrinkage treatment was 2.5%.
In this way, a polarizing film having a thickness of 3.4 μm was formed on the resin base material.

2. Production of Polarizing Plate On the surface of the polarizing film obtained above (the surface opposite to the resin substrate), a cycloolefin film with a hard coat layer (refractive index 1.53) as a protective layer (thickness: 28 μm, elasticity Rate: 2100 MPa) were bonded via an ultraviolet curable adhesive. Specifically, the curable adhesive was applied so that the total thickness was 1.0 μm, and the curable adhesive was pasted using a roll machine. Then, UV rays were irradiated from the protective layer side to cure the adhesive. Next, after slitting both ends, the resin substrate was peeled off to obtain a long-sized polarizing plate (width: 1300 mm) having a structure of protective layer / adhesive layer / polarizing film. 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 Resin Polymerization was carried out using a batch polymerization apparatus comprising two vertical reactors equipped with a stirring blade and a reflux condenser controlled to 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 parts by mass (0.139 mol), diphenyl carbonate (DPC) 63.77 parts by mass (0.298 mol) and calcium acetate monohydrate as a catalyst 1.19 × 10 ⁻² parts by mass (6.78 × 10 ^{−) 5} mol) was charged. After the inside of the reactor was replaced with nitrogen under reduced pressure, heating was performed with a heating medium, and stirring was started when the internal temperature reached 100 ° C. After 40 minutes from the start of temperature increase, the internal temperature was made to reach 220 ° C., the temperature was controlled so as to be kept at the same time, and the depressurization was started at the same time. Phenol vapor produced as a by-product with the polymerization reaction was introduced into a reflux condenser at 100 ° C., a monomer component slightly contained in the phenol vapor was returned to the reactor, and uncondensed phenol vapor was introduced into a condenser at 45 ° C. and recovered. After introducing nitrogen into the first reactor to restore the pressure to atmospheric pressure once, the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature rise and pressure reduction in the second reactor were started, and the internal temperature was set to 240 ° C. and the pressure was set to 0.2 kPa in 50 minutes. Then, the polymerization was allowed to proceed until a predetermined stirring power was obtained. When the predetermined power was reached, nitrogen was introduced into the reactor to restore the pressure, the produced polyester carbonate resin was extruded into water, and the strands were cut to obtain pellets.

3-2. Preparation of retardation film The obtained polyester carbonate-based resin (pellet) was vacuum dried at 80 ° C for 5 hours, then a single-screw extruder (Toshiba Kikai Co., Ltd., cylinder setting temperature: 250 ° C), T-die (width 200 mm). , Setting temperature: 250 ° C.), a chill roll (setting temperature: 120 to 130 ° C.) and a film forming apparatus equipped with a winder were used to prepare a long resin film having a thickness of 130 μm. The obtained long resin film was stretched while being adjusted so as to obtain a predetermined retardation 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. The Re (550) of the obtained retardation film was 141 nm, the Re (450) / Re (550) was 0.86, and the Nz coefficient was 1.12.

4. Preparation of Polarizing Plate with Retardation Layer 2. On the surface of the polarizing film of the polarizing plate obtained in step 3, above. The retardation film obtained in (1) was attached via an acrylic pressure-sensitive adhesive (thickness 5 μm). At this time, they were laminated so that the absorption axis of the polarizing film and the slow axis of the retardation film formed an angle of 45 °. In this way, a polarizing plate with a retardation layer having a structure of protective layer / adhesive layer / polarizing film / adhesive layer / retarder was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 85 μm. The obtained polarizing plate with a retardation layer was subjected to the above evaluations (5) to (6). The results are shown in Table 1.

[Example 2-1]
1. Preparation of Polarizing Film The thickness of the polarizing film obtained by changing the coating thickness of the PVA aqueous solution (coating liquid) to 13 μm was set to 4.6 μm, and the concentration of the dyeing bath was adjusted to obtain the single transmittance of the polarizing film ( A polarizing film was formed on the resin substrate in the same manner as in Example 1 except that Ts) was set to 43.0%.

2. Preparation of polarizing plate 1. A polarizing plate having a structure of protective layer / adhesive layer / polarizing film was prepared in the same manner as in Example 1 except that the polarizing film obtained in (2) was used. The single transmittance of the polarizing plate (essentially, the polarizing film) was 43.0%, and the polarization degree was 99.995%. Furthermore, 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. Production of Retardation Film A long polyester carbonate resin film having a thickness of 130 μm obtained in the same manner as in Example 1 was stretched in the width direction while adjusting so as to obtain a predetermined retardation, and a thickness of 48 μm was measured. A phase difference film was obtained. The Re (550) of the obtained retardation film was 144 nm.

4. Production of Polarizing Plate with Retardation Layer In the same manner as in Example 1, the above 2. On the surface of the polarizing film of the polarizing plate obtained in 3. above. The retardation film obtained in (1) was attached to prepare a polarizing plate with a retardation layer having a constitution of protective layer / adhesive layer / polarizer / adhesive layer / retardation layer. The total thickness of the obtained polarizing plate with a retardation layer was 87 μm. The obtained polarizing plate with a retardation layer was subjected to the above evaluations (5) to (7). The results are shown in Table 1.

[Example 2-2]
1. Production of Polarizing Film Polarizing on a resin substrate was performed 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%. A film was formed.

2. Preparation of polarizing plate 1. A polarizing plate having a structure of protective layer / adhesive layer / polarizing film was prepared in the same manner as in Example 1 except that the polarizing film obtained in (2) was used. The single transmittance of the polarizing plate (substantially, the polarizing film) was 44.0%, and the polarization degree was 99.96%. Furthermore, 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. Production of Polarizing Plate with Retardation Layer In the same manner as in Example 1, the above 2. The retardation film obtained in the same manner as in Example 2-1 is attached to the surface of the polarizing film of the polarizing plate obtained in the above to have a constitution of protective layer / adhesive layer / polarizer / adhesive layer / retardation layer. A polarizing plate with a retardation layer was produced. The total thickness of the obtained polarizing plate with a retardation layer was 87 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluations as in Example 2-1. The results are shown in Table 1.

[Example 3-1]
1. Production of Polarizing Film A polarizing film having a thickness of 4.6 μm was formed on the resin substrate in the same manner as in Example 2-1.

2. Preparation of polarizing plate 1. Except that the polarizing film obtained in 1. was used and that a triacetyl cellulose (TAC) film with a hard coat layer (hard coat layer thickness 7 μm, TAC thickness 25 μm, elastic modulus: 3600 MPa) was used as a protective layer. In the same manner as in Example 1, a polarizing plate having a structure of protective layer / adhesive layer / polarizing film was produced.

3. Preparation of Retardation Film Constituting Retardation Layer Polyester carbonate resin (pellet) obtained in the same manner as in Example 1 except that 0.7 part by mass of PMMA was melt-kneaded was vacuum dried at 80 ° C. for 5 hours. After that, it is equipped with a single-screw extruder (Toshiba Machinery Co., Ltd., cylinder setting temperature: 250 ° C), T-die (width 200 mm, setting temperature: 250 ° C), chill roll (setting temperature: 120-130 ° C), and winder. Using the film forming apparatus, a long resin film having a thickness of 105 μm was produced. The obtained long resin film was stretched 2.8 times in the width direction at 138 ° C. while adjusting so as to obtain a predetermined retardation to obtain a retardation film having a thickness of 38 μm. The Re (550) of the obtained retardation film was 144 nm, and the Re (450) / Re (550) was 0.86.

4. Preparation of Polarizing Plate with Retardation Layer 2. On the surface of the polarizing film of the polarizing plate obtained in step 3, above. The retardation film obtained in (1) was attached via an acrylic pressure-sensitive adhesive (thickness 5 μm). At this time, they were laminated so that the absorption axis of the polarizing film and the slow axis of the retardation film formed an angle of 45 °. In this way, a polarizing plate with a retardation layer having a structure of protective layer / adhesive layer / polarizing film / adhesive layer / retarder was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 81 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluations as in Example 2-1. The results are 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 as to obtain a predetermined retardation to obtain a retardation film having a thickness of 38 μm. Obtained. The Re (550) of the obtained retardation film was 140 nm.
A polarizing plate with a retardation layer having a constitution of protective layer / adhesive layer / polarizing film / adhesive layer / retardation layer in the same manner as in Example 3-1 except that the above retardation film was used as a retardation layer. Got The total thickness of the obtained polarizing plate with a retardation layer was 81 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluations as in Example 2-1. The results are 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 as to obtain a predetermined retardation to obtain a retardation film having a thickness of 38 μm. Obtained. The Re (550) of the obtained retardation film was 149 nm.
A polarizing plate with a retardation layer having a constitution of protective layer / adhesive layer / polarizing film / adhesive layer / retardation layer in the same manner as in Example 3-1 except that the above retardation film was used as a retardation layer. Got The total thickness of the obtained polarizing plate with a retardation layer was 81 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluations as in Example 2-1. The results are shown in Table 1.

[Example 4-1]
1. Production of Polarizing Film A polarizing film having a thickness of 4.6 μm was formed on the resin substrate in the same manner as in Example 2-2.

2. Preparation of polarizing plate 1. A polarizing plate having a structure of protective layer / adhesive layer / polarizing film was produced in the same manner as in Example 3-1 except that the polarizing film obtained in step 1 was used.

3. Production of Polarizing Plate with Retardation Layer A retardation film produced in the same manner as in Example 3-1 was prepared as in 2. It was attached to the surface of the polarizing film of the polarizing plate obtained in the same manner as in Example 3-1. In this way, a polarizing plate with a retardation layer having a structure of protective layer / adhesive layer / polarizing film / adhesive layer / retarder was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 81 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluations as in Example 2-1. The results are shown in Table 1.

[Example 4-2]
1. Production of Polarizing Film A polarizing film having a thickness of 4.6 μm was formed on the resin substrate in the same manner as in Example 2-2.

3. Production of Polarizing Plate with Retardation Layer A retardation film produced in the same manner as in Example 3-2 was prepared as in 2. It was attached to the surface of the polarizing film of the polarizing plate obtained in the same manner as in Example 3-1. In this way, a polarizing plate with a retardation layer having a structure of protective layer / adhesive layer / polarizing film / adhesive layer / retarder was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 81 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluations as in Example 2-1. The results are shown in Table 1.

[Example 5]
The polycarbonate resin film obtained in the same manner as in Example 1 was obliquely stretched by a method according to Example 2 in JP-A-2014-194483 to obtain a retardation film having a thickness of 58 μm. The Re (550) of the obtained retardation film was 144 nm, the Re (450) / Re (550) was 0.86, the Nz coefficient was 1.21, and the orientation angle (the direction of the slow axis). Was 45 ° with respect to the longitudinal direction. This retardation film and the polarizing plate of Example 2-2 were laminated by a roll-to-roll method with an acrylic pressure-sensitive adhesive (thickness 5 μm) interposed between the protective layer / adhesive layer / polarizing film / adhesive layer / retardation layer. A polarizing plate with a retardation layer having the constitution was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 97 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluations as in Example 2-1. The results are shown in Table 1.

[Comparative Example 1]
1. Production of Polarizer A polyvinyl alcohol-based resin film having an average polymerization degree of 2,400, a saponification degree of 99.9 mol% and a thickness of 30 μm was prepared. The polyvinyl alcohol film was dipped in a swelling bath (water bath) at 20 ° C. for 30 seconds between rolls having different peripheral speed ratios and stretched 2.4 times in the transport direction while swelling (swelling step). Dyeing is performed by dipping in a dyeing bath at 30 ° C (an aqueous solution having an iodine concentration of 0.03% by weight and a potassium iodide concentration of 0.3% by weight) so that the single transmittance after the final stretching becomes a desired value. On the other hand, the original polyvinyl alcohol film (polyvinyl alcohol film which was not stretched at all in the transport direction) was stretched 3.7 times in the transport direction (dyeing step). The immersion time at this time was about 60 seconds. Then, while dipping the dyed polyvinyl alcohol film in a crosslinking bath at 40 ° C. (an aqueous solution having a boric acid concentration of 3.0 wt% and a potassium iodide concentration of 3.0 wt%), the original polyvinyl alcohol film was immersed. It was stretched to 4.2 times in the transport direction based on the standard (crosslinking step). Further, the obtained polyvinyl alcohol film was immersed in a stretching bath at 64 ° C. (an aqueous solution having a boric acid concentration of 4.0% by weight and a potassium iodide concentration of 5.0% by weight) for 50 seconds to obtain the original polyvinyl alcohol. After being stretched to 6.0 times in the transport direction based on the alcohol film (stretching step), it was immersed in a washing bath at 20 ° C. (aqueous solution having a potassium iodide concentration of 3.0% by weight) for 5 seconds (washing). Process). The washed polyvinyl alcohol film was dried at 30 ° C. for 2 minutes to prepare a polarizer (thickness 12 μm).

2. Preparation of Polarizing Plate As an adhesive, a polyvinyl alcohol resin containing an acetoacetyl group (average polymerization degree: 1,200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 mol%) and methylolmelamine were used. The containing aqueous solution was used. This adhesive was used so that the thickness of the adhesive layer was 0.1 μm, and a triacetyl cellulose (TAC) film with a hard coat layer (hard coat layer thickness 7 μm, on one surface of the polarizer obtained above) A TAC film having a thickness of 25 μm and an elastic modulus of 3600 MPa was attached to the other surface of the polarizer with a TAC film having a thickness of 25 μm by a roll laminating machine, and then dried by heating in an oven (temperature: 60 ° C., time: 5 minutes). Then, a polarizing plate having a structure of protective layer 1 (thickness 32 μm) / adhesive layer / polarizer / adhesive layer / protective layer 2 was prepared.

3. Preparation of Polarizing Plate with Retardation Layer 2. A retardation film was attached to the surface of the protective layer 2 of the polarizing plate obtained in 1. in the same manner as in Example 1, and protective layer 1 / adhesive layer / polarizer / adhesive layer / protective layer 2 / adhesive layer / position A polarizing plate with a retardation layer having a constitution of a retardation layer was produced. The total thickness of the obtained polarizing plate with a retardation layer was 122 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluations as in Example 2-1.

[Comparative Example 2]
1. Production of Polarizer A polarizer (thickness: 12 μm) was produced in the same manner as in Comparative Example 1.

2. Production of Polarizing Plate In the same manner as in Comparative Example 1, a polarizing plate having a constitution of protective layer 1 (thickness 32 μm) / adhesive layer / polarizer / adhesive layer / protective layer 2 (thickness 25 μm) was produced.

3. Preparation of First Alignment Solidification Layer and Second Alignment Solidification Layer Constituting 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): A liquid crystal composition (coating liquid) was prepared by dissolving 3 g of a photopolymerization initiator (manufactured by BASF: trade name “Irgacure 907”) for the polymerizable liquid crystal compound in 40 g of toluene.

The surface of the polyethylene terephthalate (PET) film (thickness 38 μm) was rubbed with a rubbing cloth for orientation treatment. The direction of the orientation treatment was set to be 15 ° with respect to the direction of the absorption axis of the polarizer when it was attached to the polarizing plate, as viewed from the viewing side. The liquid crystal coating liquid was applied to the surface of the alignment treatment by a bar coater, and the liquid crystal compound was aligned by heating and drying at 90 ° C. for 2 minutes. The liquid crystal layer thus formed was irradiated with light of 1 mJ / cm ² using a metal halide lamp to cure the liquid crystal layer, thereby forming a liquid crystal alignment solidified layer A on the PET film. The thickness of the liquid crystal alignment fixed layer A was 2.5 μm, and the in-plane retardation Re (550) was 270 nm. Further, the liquid crystal alignment fixed layer A had a refractive index distribution of nx> ny = nz.
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 the direction of 75 ° with respect to the absorption axis direction of the polarizer when viewed from the viewing side. A liquid crystal alignment fixed layer B was formed. The thickness of the liquid crystal alignment fixed layer B was 1.5 μm, and the in-plane retardation Re (550) was 140 nm. Furthermore, the liquid crystal alignment fixed layer B had the refractive index distribution of nx> ny = nz. Further, Re (450) / Re (550) of the liquid crystal alignment fixed layers A and B was 1.11.

4. Preparation of Polarizing Plate with Retardation Layer 2. On the protective layer 2 side surface of the polarizing plate obtained in above, the above 3. The liquid crystal alignment solidified layer A and the liquid crystal alignment solidified layer B obtained in 1. were transferred in this order. At this time, the angle between the absorption axis of the polarizer and the slow axis of the alignment solidification layer A is 15 °, and the angle between the absorption axis of the polarizer and the slow axis of the alignment solidification layer B is 75 °. Transfer (bonding) was performed. In addition, each transfer (bonding) was performed through an ultraviolet curable adhesive (thickness 1 μm). In this way, the constitution of protective layer 1 / adhesive layer / polarizer / adhesive layer / protective layer 2 / adhesive layer / retardation layer (first orientation solidification layer / adhesion layer / second orientation solidification layer) is provided. A polarizing plate with a retardation layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 75 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluations as in Example 2-1. The results are shown in Table 1.

[Comparative Example 3]
1. Production of Polarizing Film A polarizing film having a thickness of 4.6 μm was formed on the resin substrate in the same manner as in Example 2-1.

2. Preparation of Polarizing Plate An acrylic film (surface refractive index 1.50, 20 μm) as a protective layer was provided on the surface of the polarizing film obtained above (the surface opposite to the resin substrate) with an ultraviolet curable adhesive. Pasted through. Specifically, the curable adhesive was applied so that the total thickness was 1.0 μm, and the curable adhesive was pasted using a roll machine. Then, UV rays were irradiated from the protective layer side to cure the adhesive. Next, after slitting both ends, the resin substrate was peeled off to obtain a long-sized polarizing plate (width: 1300 mm) having a structure of protective layer / adhesive layer / polarizing film.

3. Production of Polarizing Plate with Retardation Layer The same as in 2. The liquid crystal alignment fixed layer A and the liquid crystal alignment fixed layer B obtained in the same manner as in Comparative Example 2 were transferred in this order to the polarizing film surface of the polarizing plate obtained in the above. In this way, a polarizing plate with a retardation layer having a structure of protective layer / adhesive layer / polarizing film / adhesive layer / retardation layer (first alignment solidified layer / adhesive layer / second alignment solidified layer) is obtained. It was The total thickness of the obtained polarizing plate with a retardation layer was 32 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluations as in Example 2-1. The results are shown in Table 1.

[Comparative Example 4]
No potassium iodide was 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 no heating roll was used in the drying shrinkage treatment. A polarizing film and a polarizing plate were prepared in the same manner as in Example 1 except that the shrinkage in the width direction was set to 0.1% or less, and the single transmittance of the polarizing film was adjusted by adjusting the concentration of the dyeing bath. Was produced. 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. A polarizing plate with a retardation layer was produced in the same manner as in Example 1 except that this polarizing plate was used.

[Evaluation]
As is clear from the comparison between Example 1 and Comparative Examples 1, 2 and 4, the polarizing film produced by the predetermined method shows excellent optical characteristics while being thin. By using such a polarizing film, a polarizing plate with a retardation layer, which is thin, has excellent optical characteristics, and is significantly suppressed in warpage after a heating test (as a result, is excellent in handleability) It can be seen that Moreover, it is understood that an excellent reflection hue can be obtained by using in combination with a retardation layer composed of a polycarbonate resin (including a polyester carbonate resin) film. In addition, by reducing the thickness of the polycarbonate resin to 40 μm or less, the total thickness of the polarizing plate with a retardation layer to 85 μm or less, and further using a substrate having an elastic modulus of 3000 MPa or more, preferably a TAC film as a protective layer, The folding characteristics can be further improved. On the other hand, the polarizing plate with a retardation layer of Comparative Example 3 is thin, has excellent optical characteristics, and is significantly suppressed in warpage after a heating test, but has a large reflective hue and has a display characteristic. I was not satisfied with it.

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

Reference Signs List 10 polarizing plate 11 polarizing film 12 first protective layer 13 second protective layer 20 retardation layer 100 retardation layer-attached polarizing plate 101 retardation layer-attached polarizing plate

Claims

A polarizing plate including a polarizing film and 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 thereof is 8 μm or less, and the orthogonal absorbance per 1 μm of 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,
The angle formed by the slow axis of the retardation layer and the absorption axis of the polarizing film is 40 ° to 50 °,
Polarizing plate with retardation layer.
The polarizing plate with a retardation layer according to claim 1, wherein the protective layer is composed of a base material having an elastic modulus of 3000 MPa or more.
The total thickness is 90 μm or less,
The front reflection hue is 3.5 or less,
The polarizing plate with a retardation layer according to claim 1, wherein the protective layer is composed of a resin film having an elastic modulus of 3000 MPa or more.
The polarizing plate with a retardation layer according to any one of claims 1 to 3, wherein the protective layer is made of a triacetyl cellulose resin film.
The polarizing plate includes the polarizing film and the protective layer disposed only on one side of the polarizing film,
The polarizing plate with a retardation layer according to claim 1, wherein the retardation layer is attached to the polarizing film via an adhesive layer.
The polarizing plate with a retardation layer according to any one of claims 1 to 5, wherein the retardation layer is composed of a polycarbonate resin film.
The polarizing plate with a retardation layer according to claim 1, wherein the retardation layer is composed of a polycarbonate resin film having a thickness of 40 μm or less.
8. The ratio (A 470 / A 600 ) of the orthogonal absorbance A 470 at a wavelength of 470 nm and the orthogonal absorbance A 600 at a wavelength of 600 nm of the polarizing film (A 470 / A 600 ) is 0.7 to 2.00. Polarizing plate with retardation layer.
The polarizing plate with a retardation layer according to any one of claims 1 to 8, wherein the orthogonal b value of the polarizing film is more than -10 and +10 or less.
The polarizing plate with a retardation layer according to any one of claims 1 to 9, wherein the iodine concentration of the polarizing film is 3.0% by weight or more.
The polarizing plate with a retardation layer according to claim 1, wherein the single transmittance of the polarizing film is 42.5% or more.
The position according to any one of claims 1 to 11, further comprising another retardation layer outside the retardation layer, and the refractive index characteristics of the another retardation layer exhibit a relationship of nz> nx = ny. Polarizing plate with retardation layer.
The polarizing plate with a retardation layer according to any one of claims 1 to 12, further comprising a conductive layer or an isotropic substrate with a conductive layer outside the retardation layer.
Long shape,
The polarizing film has an absorption axis in the longitudinal direction,
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 the lengthwise direction,
The polarizing plate with a retardation layer according to any one of claims 1 to 13.
The polarizing plate with a retardation layer according to claim 14, which is wound in a roll shape.
An image display device comprising the polarizing plate with a retardation layer according to any one of claims 1 to 13.
The image display device according to claim 16, which is an organic electroluminescence display device or an inorganic electroluminescence display device.