TW202035124A - Image display device and method for manufacturing same - Google Patents

Abstract

This image display device comprises a polarizing plate (36) that is attached to the surface of an image display cell (10) through an adhesive layer (39). The polarizing plate comprises a polarizer (31) and a phase difference film (35), wherein the phase difference film is disposed between the polarizer and the image display cell. The in-plane birefringence of the phase difference film at a wavelength of 550 nm is 8 * 10<SP>-3</SP> or more. It is preferable that an absolute value |[Theta]1 - [Theta]2| of a difference between an angle [Theta]1 between an absorption axis direction of the polarizer and a slow axis direction of the phase difference film in a state in which the polarizing plate is attached to the image display cell through the adhesive layer and an angle [Theta]2 between the absorption axis direction of the polarizer and the slow axis direction of the phase difference film when the polarizing plate is peeled from the image display cell is 0.4 DEG or less.

Description

Image display device and manufacturing method thereof

The present invention relates to an image display device provided with a polarizing plate formed by laminating a polarizing element and a retardation film on the surface of an image display unit, and a manufacturing method thereof.

As mobile devices such as mobile phones, smart phones, and tablet terminals; in-vehicle devices such as car navigation devices; various image display devices such as computer monitors and televisions, liquid crystal display devices or organic EL (Electroluminescence, electroluminescence) are widely used. Luminous) display device. According to the display principle of the liquid crystal display device, polarizing elements are arranged on both sides of the liquid crystal cell. A retardation film may be arranged between the liquid crystal cell and the polarizing element for the purpose of optical compensation such as contrast improvement or viewing angle enlargement. In organic EL display devices, in order to prevent external light from being reflected by the metal electrode (cathode), it is sometimes regarded as a mirror surface. A circular polarizing plate (a phase difference between a polarizing element and a retardation of 1/4 wavelength is arranged on the visible side of the cell Film laminate).

The polarizing plate generally has a structure in which a transparent protective film (polarizing element protective film) is bonded to one or both sides of a polarizing element, and a retardation film may be used as the transparent protective film. In addition, sometimes a transparent protective film is attached to the surface of the polarizing element, and a retardation film is attached to it. A polarizing plate formed by laminating a polarizing element and a retardation film is generally bonded to the substrate on the surface of the image display unit through an adhesive.

If the optical properties of the retardation film arranged between the polarizing element and the image display unit are not uniform in the plane, the displayed image will appear uneven. Therefore, the retardation film requires uniformity in film thickness or optical properties. For example, Patent Document 1 discloses a technique for making the optical axis direction of the retardation film uniform.

It is known that if the image display device is exposed to a high-temperature and high-humidity environment, or placed in a sudden environmental change, the display unevenness occurs due to the change of the optical characteristics of the retardation film, or the deterioration of the polarizing element, etc., in order to provide Various methods have been proposed for polarizing plates that are not prone to changes in optical characteristics. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2016-109924

[The problem to be solved by the invention]

In response to the increasing demand for lighter or thinner displays, retardation films with smaller film thicknesses have been used. Since the retardation of the retardation film is the product of the birefringence and the thickness, in order to cope with the thinning, it is necessary to increase the birefringence of the retardation film by using a high birefringence material or increasing the stretching ratio.

In addition to weight reduction or thinning, high brightness and high image quality of displays are being promoted, and subtle shortcomings or unevenness that have not been recognized before are becoming prominent as quality issues. If a polarizing plate is laminated with a polarizing element and a retardation film with a large birefringence and bonded to the image display unit through an adhesive, sometimes the polarizing plate itself has high optical uniformity, as shown in the figure. The visual recognition is uneven in the display image of the image display device.

Such display unevenness is different from the unevenness caused by the unevenness of the optical characteristics, or the unevenness caused by the time-dependent changes in the high temperature and high humidity environment, etc., and there is no related reason or solution. Opinions on policies, etc. In view of the foregoing, an object of the present invention is to provide an image display device with a polarizing plate formed by laminating a phase difference film with high birefringence and a polarizing element, and the unevenness of the displayed image is reduced. [Technical means to solve the problem]

The image display device of the present invention includes a polarizing plate attached to the surface of the image display unit via an adhesive layer. The polarizing plate includes a polarizing element and a retardation film, and the retardation film is arranged between the polarizing element and the image display unit. The in-plane birefringence of the retardation film at a wavelength of 550 nm is 8×10 ^-3 or more.

A phase difference film with an in-plane birefringence of 8×10 ^-3 or more at a wavelength of 550 nm in an area layer of the polarizing element, and an adhesive layer is attached to the phase difference film. The polarizing plate is attached to the image display unit to form an image display device. In the polarizing plate with adhesive, the retardation film can also be connected to the adhesive layer.

In the adhesive layer provided on the retardation film, the value G'/D obtained by dividing the shear storage modulus G'at a temperature of 25°C by the thickness D can also be 5 kPa/μm or more. The thickness of the adhesive layer can also be 25 μm or less.

The lamination pressure when attaching the polarizing plate with the adhesive to the image display unit is preferably 0.05 to 0.4 MPa.

The in-plane retardation of the retardation film can also be 200 nm or more. The retardation film may satisfy the refractive index nx in the slow axis direction in the plane, the refractive index ny in the advancing axis direction in the plane, and the refractive index nz in the thickness direction satisfying nx>nz>ny. In the retardation film, when tension is applied to the direction of 45° with respect to the slow axis direction, the amount of change with respect to the tension slow axis may be 0.1°/N/10 mm or more.

In the adhesive-attached polarizing plate before being attached to the image display unit, the angle θ ₀ formed by the absorption axis direction of the polarizing element and the retardation axis direction of the retardation film, and the adhesive-attached polarizing plate and The absolute value of the difference of the angle θ ₁ formed by the absorption axis direction of the polarizing element and the retardation axis direction of the retardation film after the image display unit is attached |θ ₁ -θ ₀ | is preferably 0.4° or less. In addition, the absolute value of the angle θ ₂ formed by the absorption axis direction of the polarizing element and the retardation axis direction of the retardation film when the polarizing plate with the adhesive is peeled off from the image display unit and θ ₁ |θ ₁ -Θ ₂ | is preferably 0.4° or less. θ ₁ can also be within the range of 0±0.4° or 90±0.4°. [Effects of Invention]

Even when a retardation film with a small thickness and a large birefringence is used, it is possible to obtain an image display device that is less prone to display unevenness and has excellent display quality.

The image display device of the present invention includes a polarizing plate attached to the surface of the image display unit via an adhesive layer. The polarizing plate includes a polarizing element and a retardation film arranged on one surface of the polarizing element, and the retardation film is arranged between the polarizing element and the image display unit. As an image display device in which a phase difference film is arranged between a polarizing element and an image display unit, a liquid crystal display device and an organic EL display device can be mentioned.

[Construction of liquid crystal display device] FIG. 1 is a cross-sectional view of the structure of a liquid crystal display device according to an embodiment. The liquid crystal display device 201 includes a liquid crystal panel 100 and a light source 105. In the liquid crystal panel 100, a first polarizing plate 36 is provided on the visible side surface of the liquid crystal cell 10, and a second polarizing plate 56 is provided on the light source 105 side of the liquid crystal cell 10.

The liquid crystal cell 10 includes a liquid crystal layer 11 between two substrates 13 and 15. The substrates 13 and 15 are transparent substrates such as glass substrates or plastic substrates. In a general configuration, a color filter and a black matrix are provided on one substrate, and a switching element for controlling the electro-optical characteristics of the liquid crystal is provided on the other substrate.

The liquid crystal layer 11 contains liquid crystal molecules aligned in a specific direction in an electroless state. When a voltage is applied, the alignment direction (director) of the liquid crystal molecules changes. For example, in an in-plane switching (IPS, In-Plane Switching) liquid crystal cell, the liquid crystal molecules of the liquid crystal layer 11 are aligned parallel and uniformly with respect to the substrate plane in the absence of an electric field (horizontal alignment), and if a voltage is applied, The director rotates in the plane of the substrate. The alignment direction of the liquid crystal molecules in the IPS mode liquid crystal cell in the electroless state can also be slightly inclined relative to the substrate plane. In the liquid crystal cell of the IPS method, the angle (pretilt angle) formed by the substrate plane in the electroless state and the alignment direction of the liquid crystal molecules is generally 10° or less.

The first polarizing plate 36 is attached to the visible side substrate 13 of the liquid crystal cell 10 via the first adhesive layer 39. A second polarizing plate 56 is attached to the light source side substrate 15 of the liquid crystal cell 10 via the second adhesive layer 59.

The polarizing plates 36 and 56 include polarizing elements 31 and 51, respectively. The polarizing elements 31 and 51 absorb the vibrating light in the direction of the absorption axis, and transmit (eject) the vibrating light in the direction of the transmission axis in the form of linear polarization. The polarizing element 31 of the first polarizing plate 36 and the polarizing element 51 of the second polarizing plate 56 are arranged such that their absorption axis directions are orthogonal to each other.

Examples of polarizing elements include hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, ethylene-vinyl acetate copolymer-based partially saponified films, iodine or dichroic dyes, etc. Dichroic substances are adsorbed and uniaxially stretched; polyene-based alignment films such as dehydrated polyvinyl alcohol or dehydrochlorinated polyvinyl chloride.

Among them, in terms of having a higher degree of polarization, it is preferable to use a polyvinyl alcohol film, such as polyvinyl alcohol or partially formalized polyvinyl alcohol, to adsorb and align dichroic substances such as iodine or dichroic dyes. Polyvinyl Alcohol (PVA) made in a specific direction is a polarizing element. For example, by performing iodine dyeing and stretching with a polyvinyl alcohol-based film, a PVA-based polarizing element can be obtained.

A thin polarizer with a thickness of 10 μm or less can also be used as the PVA-based polarizer. As the thin polarizing element, for example, Japanese Patent Laid-Open No. 51-069644, Japanese Patent Laid-Open No. 2000-338329, WO2010/100917 Manual, Japanese Patent No. 4693205, Japanese Patent No. 4751481 Thin polarizing film described in etc. Such a thin polarizing element is obtained by, for example, stretching the PVA-based resin layer and the resin substrate for stretching in the state of a laminate, and performing iodine dyeing.

In the first polarizing plate 36, transparent protective films 33 and 35 are attached to both surfaces of the polarizing element 31. In the second polarizing plate 56, transparent protective films 53 and 55 are attached to both sides of the polarizing element 51.

The thickness of the transparent protective films 33, 35, 53, 55 is, for example, about 5 to 200 μm. As the resin material constituting the protective film, a polymer having excellent transparency, mechanical strength, and thermal stability is preferably used. Specific examples of such polymers include: cellulose resins such as acetyl cellulose, polyester resins, polycarbonate resins, polyamide resins, polyimide resins, and maleic resins. Diimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (nor ene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins , Polymeric resins, and their mixtures or copolymers, etc.

The polarizing elements 31, 51 and the transparent protective films 33, 35, 53, 55 are bonded via an adhesive or an adhesive (not shown). As the adhesive or adhesive used for bonding the polarizing element and the transparent protective film, acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, poly Vinyl ether, vinyl acetate/vinyl chloride copolymer, modified polyolefin, epoxy-based polymer, fluorine-based polymer, rubber-based polymer, etc. are used as the base polymer.

In FIG. 1, in the first polarizer 36 and the second polarizer 56, transparent protective films are provided on both sides of the polarizing elements 31 and 51, but the polarizing plates may be provided with transparent protective films only on one side of the polarizing element. In addition, two or more transparent protective films may be attached to one surface of the polarizing element.

As the adhesive constituting the adhesive layers 39 and 59, acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, vinyl acetate can be selected as appropriate. Rubber-based polymers such as vinyl chloride copolymers, modified polyolefins, epoxy-based, fluorine-based, natural rubber, and synthetic rubber are used as base polymers. In particular, acrylic adhesives are preferably used in terms of excellent optical transparency, and exhibiting suitable adhesive properties such as wettability, aggregation and adhesion. The thickness of the adhesive layers 39 and 59 is about 5-50 μm.

In the formation of the liquid crystal display device, the polarizing element and the transparent protective film are attached in advance to form the polarizing plates 36 and 56. The adhesive layers 39 and 59 are attached to the surfaces of the polarizing plates 36 and 56 to produce the polarizing plate with adhesive . Using a laminating machine such as a roller laminator, the polarizing plate with the adhesive is bonded to the liquid crystal cell 10.

[Retardation film] In the liquid crystal display device of one embodiment, the transparent protective film 35 of the first polarizing plate 36 is a retardation film. The retardation film 35 arranged between the polarizing element 31 and the liquid crystal cell 10 can achieve optical compensation such as contrast improvement or viewing angle enlargement. For example, in an IPS type liquid crystal display device, when viewing from a tilted direction at an angle of 45 degrees (azimuth angle of 45 degrees, 135 degrees, 225 degrees, 315 degrees) with respect to the absorption axis of the polarizing element, the black display leaks light Larger, lower contrast or color shift is likely to occur. By disposing a retardation film with an in-plane retardation of 1/2 of the wavelength λ and an Nz coefficient of 0.5 between the liquid crystal cell and the polarizing element, the black brightness in the oblique direction can be reduced and the contrast can be improved.

Furthermore, regarding the Nz coefficient of the retardation film, the in-plane refractive index in the slow axis direction is nx, the refractive index in the advancing axis direction is ny, and the thickness direction refractive index is nz, which is defined as Nz=(nx-nz)/(nx-ny). The in-plane retardation Re of the retardation film is expressed as Re=(nx-ny)×d. d is the thickness of the retardation film.

In order to make a thin retardation film with a small thickness (for example, 35 μm or less) to exhibit an in-plane retardation of λ/2 for light at a wavelength near 550 nm with high visual sensitivity, the in-plane retardation film is required The birefringence Δn=(nx-ny) is 8×10 ^-3 or more. Such a retardation film with a small thickness and large birefringence is described in, for example, Japanese Patent Laid-Open No. 2005-181451, Japanese Patent Laid-Open No. 2011-227430, Japanese Patent Laid-Open No. 2016-109924, etc. It can be formed by coating the resin solution on the support film, drying the solvent, and extending the laminate of the support and the resin coating film. By treating the retardation film with a small thickness as a laminate with the support film, the operability can be improved. A heat-shrinkable film is used as a support film, and the laminate is shrunk in a direction orthogonal to the stretching direction during stretching, thereby obtaining a retardation film having refractive index anisotropy of nx>nz>ny. In addition to the support film, a heat-shrinkable film may be attached separately to impart shrinkage force in a specific direction.

The manufacturing method of the retardation film is not limited to the above, and various well-known methods can be adopted. In addition, the refractive index anisotropy or retardation of the retardation film can be appropriately selected according to the type of liquid crystal cell and the like. The retardation film can also be positive A plate (nx>ny=nz), negative B plate (nx>ny>nz), negative A plate (nz=nx>ny), or positive B plate (nz>nx>ny) .

It is preferable to use a polymer having a positive intrinsic birefringence in the production of a retardation film having a refractive index anisotropy of nx>nz>ny, a positive A plate, and a negative B plate. A polymer with a positive inherent birefringence refers to a case where the refractive index of the alignment direction becomes relatively larger when the polymer is aligned by stretching or the like. As a polymer with positive intrinsic birefringence, for example, polycarbonate resin, polyester resin such as polyethylene terephthalate or polyethylene naphthalate; polyarylate resin, poly Sulfide resins such as polyether sulfide; sulfide resins such as polyphenylene sulfide; polyimide resins, cyclic polyolefin (polynorene) resins, polyamide resins, polyethylene or poly Polyolefin resins such as propylene; cellulose esters, etc. In addition, liquid crystal materials can also be used as materials with positive intrinsic birefringence.

In the production of the negative A plate and the positive B plate, it is preferable to use a polymer having a negative inherent birefringence. A polymer with negative inherent birefringence refers to a case where the refractive index of the alignment direction becomes relatively small when the polymer is aligned by stretching or the like. As a polymer having a negative inherent birefringence, for example, a chemical bond or functional group having a large polarization anisotropy such as an aromatic or a carbonyl group is introduced into the side chain of the polymer. Specifically, it can be exemplified : Acrylic resin, styrene resin, maleimide resin, fumarate resin, etc. In addition, liquid crystal materials can also be used as materials with negative inherent birefringence. For example, a negative A plate can be obtained from a disc-type liquid crystal aligned perpendicularly to the film surface.

In the case of using a polymer as the material of the retardation film, the retardation film can be formed by extending the polymer film to improve the molecular orientation in a specific direction. The stretching method of the polymer film may, for example, be a longitudinal uniaxial stretching method, a horizontal uniaxial stretching method, a vertical and horizontal successive biaxial stretching method, and a vertical and horizontal simultaneous biaxial stretching method. As the stretching mechanism, any appropriate stretching machine, such as a roll stretching machine, a tenter stretching machine, a zooming machine, or a linear motor type biaxial stretching machine, can be used. As described above, the shrinkage force of the heat shrinkable film can also be used to control the refractive index anisotropy during stretching. A laminate formed by forming a liquid crystal layer on a substrate can be used directly as a retardation film, or can be transferred to other films.

As described above, in order to achieve a small thickness and a large in-plane retardation (for example, 200 nm or more), the in-plane birefringence Δn=(nx-ny) of the retardation film is preferably 8×10 ^-3 or more. The in-plane birefringence Δn of the retardation film may be 1.0×10 ^-2 or more, 1.2×10 ^-2 or more, or 1.3×10 ^-2 or more.

From the viewpoint of thinning, the thickness of the retardation film is preferably 35 μm or less. The thickness of the retardation film may also be 30 μm or less, 25 μm or less, or 20 μm or less. The thickness of the retardation film is generally 1 μm or more, and may be 3 μm or more, 5 μm or more, or 7 μm or more. As described above, by extending the resin coating film integrally with the film substrate, a retardation film with a small thickness can be produced without impairing handleability.

[Polarizing plate with adhesive] By bonding the retardation film as the transparent protective film 35 on one side of the polarizing element 31, a polarizing plate can be obtained. It is also possible to bond an optically isotropic film as a transparent protective film 35 on the polarizing element 31, and bond the retardation film to the transparent protective film 35 via an appropriate adhesive or adhesive. A transparent protective film 33 is attached to the other surface of the polarizing element 31. The transparent protective film 33 may also be omitted. When the transparent protective film 33 is omitted, the polarizing plate 36 is provided with the transparent protective film 35 only on one side of the polarizing element.

In the polarizing plate used in the IPS type liquid crystal display device, the polarizing element and the retardation film are bonded so that the absorption axis direction of the polarizing element and the retardation axis direction of the retardation film become parallel or orthogonal. In order to improve the accuracy of the optical axis, the bonding of the polarizing element and the retardation film is preferably implemented in a roll-to-roll manner. Polarizing elements generally have an absorption axis in the longitudinal direction (extending direction). Therefore, when the absorption axis direction of the polarizing element is parallel to the retardation axis direction of the retardation film, it is preferable to use a retardation film having a retardation axis in the longitudinal direction, and the absorption axis direction of the polarizing element is the same as the retardation film. When the direction of the late axis is orthogonal, it is preferable to use a retardation film having a late axis in the width direction.

By attaching the adhesive layer 39 to the surface of the retardation film 35, an adhesive-attached polarizing plate with an adhesive layer 39 attached to the surface of the polarizing plate 36 can be obtained. The bonding of the adhesive layer is also preferably implemented in a roll-to-roll manner.

In the period until the polarizing plate is attached to the image display unit, it is preferable to temporarily adhere the release film (separator) to the exposed surface of the adhesive layer 39 attached to the surface of the polarizing plate in advance. As the release film, for example, one obtained by peeling off the surface of the plastic film is used.

[Lamination of the polarizing plate with adhesive facing the image display unit] A polarizing plate with an adhesive having a retardation film 35 between the polarizing element 31 and the adhesive layer 39 is attached to the substrate 13 of the liquid crystal cell 10 to form a liquid crystal panel. On the substrate 15 on the light source side of the liquid crystal cell, an adhesive-attached polarizing plate formed by attaching an adhesive layer 59 to the surface of the polarizing plate 56 is attached. The polarizing plates 36 and 56 on the front and back sides can be attached at the same time or attached to the liquid crystal cell 10 successively.

In bonding using an adhesive layer, from the viewpoint of improving the adhesion in the bonding interface and preventing the mixing or peeling of bubbles, pressure is applied. As the pressure bonding method, a roller type or a tumbler type may be mentioned.

As shown in the embodiments described later, a retardation film with high birefringence is liable to change the direction of the optical axis due to tension (stress). The change in the optical axis direction of the retardation film due to tension is determined as follows: The retardation film is cut into short strips with a width of 10 mm at an angle of 45° with respect to the slow axis direction. Tension is applied to the long side direction, and the slow axis direction is measured in this state. Take the tension as the horizontal axis and the angle (the amount of change) of the slow axis as the vertical axis to draw. The slope of the straight line obtained by the least square method is the amount of change relative to the tension axis (unit: °/N/ 10 mm).

In a retardation film with an in-plane birefringence of 8×10 ^-3 or more, the amount of change with respect to the slow axis of tension may become 0.1°/N/10 mm or more. The retardation film with smaller thickness and larger in-plane birefringence tends to change with respect to the retardation axis of tension, and the change of optical axis with respect to tension can be 0.2°/N/ Above 10 mm or above 0.3°/N/10 mm.

In this way, sometimes if a polarizing plate with a retardation film whose direction of the optical axis is easily changed is attached to the image display unit, the bonding angle of the polarizing element and the retardation film will be shifted, which is regarded as displaying an image The optical unevenness.

The amount of change (offset) between the direction of the absorption axis of the polarizing element 31 and the direction of the optical axis (delay axis or advance axis) of the retardation film 35 is preferably 0.4° or less, more preferably 0.3° or less . The amount of change in the axis angle is the angle θ ₁ formed by the absorption axis direction of the polarizing element 31 and the retardation axis direction of the retardation film 35 in a state where the polarizing plate 36 is attached to the image display unit via the adhesive layer 39, The difference between the angle θ ₀ between the two before lamination. The amount of change in the shaft angle can also be 0.2° or less or 0.1° or less. If the offset of the axis angle is 0.4° or less, even when the birefringence of the retardation film 35 is large, the generation of optical unevenness can be suppressed. The smaller the offset, the unevenness Produce the tendency to be more restrained.

When the polarizing plate is attached to the image display unit via the adhesive layer, the angle between the absorption axis direction of the polarizing element and the optical axis direction of the retardation film is preferably 0.4° or less, more preferably 0.3° or less , And more preferably 0.2° or less. When the absorption axis direction of the polarizing element is parallel to the retardation axis direction of the retardation film, θ _{1 is} preferably in the range of 0±0.4°, more preferably in the range of 0±0.3°, and more preferably 0 Within ±0.2°. When the absorption axis direction of the polarizing element is orthogonal to the retardation axis direction of the retardation film, θ _{1 is} preferably within the range of 90±0.4°, more preferably within the range of 90±0.3°, and more preferably Within the range of 90±0.2°.

The greater the thickness of the adhesive layer 39 used for bonding the polarizing plate 36 (retardation film 35) and the image display unit 10, and the softer the adhesive, the difference between the axis angles of the polarizing element 31 and the retardation film 35 The greater the deviation. The shear storage modulus G'at normal temperature (25°C) can be used as an index of the hardness of the adhesive. The larger the G', the harder the adhesive system, and the smaller the G', the softer.

The shear storage modulus G'of the adhesive layer 39 at a temperature of 25°C divided by the thickness D is the larger G'/D (the harder and thinner the adhesive layer), the more the polarizer passes through the adhesive layer When it is attached to the image display unit, the deviation of the axis angle tends to be smaller. In the adhesive layer 39, G'/D is preferably 5.0 kPa/μm or more, more preferably 5.2 kPa/μm or more. When G'/D is too large, the subsequent retention may decrease, and there may be poor bonding such as air bubbles being mixed into the bonding interface. Therefore, in the adhesive layer 39, G'/D is preferably 28 kPa/μm or less, and more preferably 25 kPa/μm or less.

The thickness D of the adhesive layer 39 is preferably 5-25 μm, more preferably 7-20 μm. The shear storage modulus G′ of the adhesive layer 39 at 25° C. is preferably 50 kPa or more, more preferably 60-250 kPa, and still more preferably 70-200 kPa.

In addition to the physical properties of the adhesive used for bonding the polarizer and the image display unit, the bonding pressure (lamination pressure) when bonding the polarizer with the adhesive to the image display unit may also affect The deviation of the axis angle between the polarizing element and the retardation film has an influence. The higher the lamination pressure, the greater the deviation of the axis angle between the polarizing element and the retardation film. When attaching a polarizing plate with a retardation film with a large birefringence and a large optical axis change with respect to the value of the tension to the image display unit, the lamination pressure is preferably 0.4 MPa or less, More preferably, it is 0.3 MPa or less. On the other hand, if the lamination pressure is too low, adhesion failures such as air bubbles mixing into the bonding interface may occur. Therefore, the lamination pressure is preferably 0.05 MPa or more, more preferably 0.1 MPa or more.

As described above, when the birefringence of the retardation film is large, the axis angle change (offset) caused by the bonding is likely to occur. Because of this, the displayed image may appear optically uneven. However, by adjusting the thickness and hardness of the adhesive layer, and/or the lamination pressure during bonding, the unevenness can be suppressed.

The physical properties and lamination pressure of the adhesive layer 59 when the polarizing plate 56 on the other side is bonded to the liquid crystal cell 10 are not particularly limited. The thickness and shear storage modulus of the adhesive layer 59 may be the same as or different from the adhesive layer 39. The lamination pressure when the polarizing plate 56 is attached may be the same as or different from the lamination pressure when the polarizing plate 36 is attached.

<Estimation mechanism of uneven generation and reduction> As described above, in an image display device where display unevenness occurs, the angle between the absorption axis direction of the polarizing element and the retardation axis direction of the retardation film is between before and after lamination The amount of change |θ ₁ -θ ₀ | is relatively large. If the polarizing plate is peeled off from the image display device with uneven display (secondary processing), the angle θ ₂ formed by the absorption axis direction of the polarizing element and the retardation axis direction of the retardation film is measured, and it becomes the bonding The previous value is roughly equal. That is, the angle θ ₀ formed by the absorption axis direction of the polarizing element before bonding the polarizing plate and the image display unit and the retardation axis direction of the retardation film, and the polarizing plate with the adhesive and the image display unit The angle θ ₂ formed by the absorption axis direction of the polarizing element after the bonding and secondary processing and the retardation axis direction of the retardation film are approximately equal. In addition, if the polarizing plate after the secondary processing is reattached to the image display unit with a low lamination pressure, the change in the axis angle is small, and there is no unevenness.

Therefore, the change in the axis angle when the polarizing plate is attached to the image display unit can be described as a reversible change. It is considered that the display unevenness caused by the change of the reversible axis angle is caused by the residual strain caused by the pressure when the polarizing plate is attached. For example, if lamination is performed with a high lamination pressure, the adhesive layer with a lower elastic modulus will deform compared with the film, and elastic strain will occur. It is considered that since pressure is applied from the direction of the normal line of the bonding surface when the roller laminator or drum laminator is used for laminating, the adhesive layer accumulates strain due to pressure from various directions.

If the pressure is released after bonding, the adhesive layer will return to its original shape. However, since the adhesive layer is bonded to the substrate of the image display unit, the degree of freedom of deformation is low compared to before bonding. Therefore, the adhesive layer cannot be completely restored to its original shape, and part of the strain caused by the pressure applied from various directions during bonding remains inside the adhesive layer. It is considered that the strain is the main cause of strain in the bonding interface with the retardation film attached to the adhesive layer, which changes the optical axis of the retardation film.

If the lamination pressure during lamination is reduced, the strain accumulated in the adhesive layer 39 is smaller, so the strain remaining in the adhesive layer after lamination is also smaller, and the strain in the lamination interface with the retardation film Also becomes smaller. In addition, when the thickness D of the adhesive layer 39 is small and the shear storage modulus G'is large, the amount of deformation of the adhesive layer caused by pressure is small, so the strain remaining in the adhesive layer 39 If it is smaller, the strain in the bonding interface with the retardation film also becomes smaller. Therefore, if a thinner and harder adhesive is used for bonding at a low lamination pressure, it is difficult to accumulate the strain that causes the change of the optical axis direction of the retardation film. The amount of change of the optical axis|θ _1- θ ₀ | is small, so it is estimated that the occurrence of unevenness is suppressed.

[Other optical components] The liquid crystal panel 100 in which polarizing plates 36 and 56 are attached to both sides of the liquid crystal cell 10 is combined with the light source 105 to form a liquid crystal display device. The liquid crystal display device may also include optical layers or other members other than the above. For example, a brightness enhancement film (not shown) may be provided between the liquid crystal panel 100 and the light source 105. The brightness enhancement film may be laminated with the polarizing plate 56 on the light source side.

For the purpose of imparting scratch resistance, etc., a hard coat layer can be provided on the transparent protective film 33 on the visible side. In addition, an anti-reflection layer may be provided on the transparent protective film 33. Furthermore, a touch panel sensor, a cover window, etc. may be arranged on the viewing side of the polarizing plate 36 on the viewing side.

In the above example, the example in which the polarizing plate 36 arranged on the visible side of the liquid crystal cell 10 includes the phase difference film 35 with high birefringence is described. The film 55 arranged on the liquid crystal cell side of the polarizing plate 56 on the light source side may also be High birefringence retardation film. In this case, by using the larger G'/D as the adhesive layer 59 for bonding the polarizing plate 56 and the liquid crystal cell 10, and/or reducing the lamination pressure during bonding, unevenness can be suppressed The production.

The absorption axis direction of the polarizing element and the retardation axis direction of the retardation film can also be arranged at non-parallel and non-orthogonal angles. Even when the polarizing element and the retardation film are laminated at a non-parallel and non-orthogonal angle between the optical axes of the two, the polarizer and the image display unit can be bonded by using the larger G'/D The adhesive layer and/or reduce the lamination pressure during lamination, so that the deviation of the optical axis before and after lamination is small, and the unevenness can be suppressed.

[Organic EL display device] As an image display device provided with a polarizing plate in which a polarizing element and a retardation film are laminated at a non-parallel and non-orthogonal angle of the optical axis, in addition to a liquid crystal display device, an organic EL display device can be exemplified. The organic EL display device 202 shown in FIG. 2 includes a bottom emission type organic EL unit 70 in which a transparent electrode 72, an organic light-emitting layer 71, and a metal electrode 74 are sequentially provided on a transparent substrate 73.

As the transparent substrate 73, a glass substrate or a plastic substrate is used. The organic EL light-emitting layer 71 may include an electron transport layer, a hole transport layer, etc., in addition to an organic layer that itself functions as a light-emitting layer. The transparent electrode 72 is a metal oxide layer or a metal thin film, which transmits light from the organic light-emitting layer 71. Therefore, the light (image light) from the organic light emitting layer 71 is transmitted through the transparent electrode 72 and the substrate 73, and is extracted by the visible side.

The metal electrode 74 is light reflective. Therefore, if external light enters the inside of the organic EL unit from the substrate 73, the light is reflected by the metal electrode 74, and the reflected light from the outside is regarded as a mirror surface. From the viewpoint of preventing the reflected light from being re-emitted to the outside through the metal electrode 74 and improving the visibility and design of the display device, a circular polarizing plate 37 is attached to the visible side surface of the organic EL unit 70 via an adhesive layer 39.

The circular polarizing plate 37 has a structure in which transparent protective films 33 and 34 are layered on two areas of the polarizing element 31, and the transparent protective film 34 disposed between the polarizing element 31 and the organic EL unit 70 is a retardation film. When the retardation film 34 has a retardation of λ/4, and the angle formed by the slow axis direction of the retardation film 34 and the absorption axis direction of the polarizing element 31 is 45°, the laminated body of the polarizing element and the retardation film ( The polarizing plate 37) functions as a circular polarizing plate. The retardation film 34 is a quarter-wavelength plate, and the angle formed by the retardation film 34 and the optical axis of the polarizing element 31 is 45°. The structure of the polarizing plate 37 is the same as the above-mentioned polarizing plate 36 except for this.

In addition, the retardation film constituting the circular polarizing plate may be formed by laminating two or more layers. For example, by stacking the polarizing element, the λ/2 plate, and the λ/4 plate in such a way that the optical axis of each is at a specific angle, it is possible to obtain a wide band across visible light that functions as a circular polarizer. Circular polarizer.

By bonding the polarizing element 31 and the retardation film 34 through an appropriate adhesive or adhesive, the circular polarizing plate 37 can be obtained. The optically isotropic film may be bonded to the polarizing element 31, and the retardation film may be bonded to the optically isotropic film. A transparent protective film 33 may also be attached to the other side of the polarizing element 31.

An organic EL display device is formed by bonding an adhesive-attached polarizing plate having a retardation film 34 between the polarizing element 31 and the adhesive layer 39 to the substrate 73 of the organic EL unit 70. Regarding the implementation of the liquid crystal display device, similar to the above, by using the larger G'/D as the adhesive layer 39 for bonding the organic EL unit to the polarizing plate, and/or reducing the lamination pressure during bonding Therefore, even if the retardation film 34 has high birefringence, the amount of change |θ ₁ -θ ₂ | of the axial angle before and after bonding can be set to 0.4° or less to suppress the occurrence of unevenness.

In the foregoing, an example of the bottom emission type organic EL unit 70 has been described, and the organic EL unit may be a top emission type. In general, a top-emission organic EL unit is provided with a metal electrode, an organic light-emitting layer, and a transparent electrode in sequence on a substrate. A sealing substrate is arranged on the transparent electrode layer, and a circular polarizing plate is attached to the sealing substrate. The organic EL display device may further include a touch panel sensor, a cover window, or the like on the viewing side of the circular polarizer 37. [Example]

Hereinafter, examples are given to explain the present invention in more detail, but the present invention is not limited by the following examples.

[Adhesive Sheet] ＜Preparation of adhesive composition＞ (Adhesive composition P) In the reaction vessel, make butyl acrylate (BA): 99 parts by weight and 4-hydroxybutyl acrylate (4HBA): 1 part by weight as monomers, and 2,2'-azobisisobutyronitrile (AIBN): As a polymerization initiator, 0.3 part was added together with ethyl acetate and reacted at 60°C for 4 hours under a nitrogen stream. After that, ethyl acetate was added to the reaction solution to obtain a solution of an acrylic polymer with a weight average molecular weight of 1.65 million. In this solution, benzyl peroxide ("Nyper BMT" manufactured by NOF Corporation): 0.3 parts by weight and trimethylolpropane xylylene diisocyanate (Mitsui Chemicals The manufactured "Takenate D110N"): 0.1 parts by weight as a crosslinking agent and a silane coupling agent ("A-100" manufactured by Soken Chemicals) to obtain an adhesive composition A.

(Adhesive composition Q) In the reaction vessel, make BA: 94.9 parts by weight, acrylic acid (AA): 5 parts by weight, 2-hydroxyethyl acrylate (2HEA): 0.1 parts by weight as monomers, and AIBN: 0.1 parts by weight as polymerization initiators, It was put together with ethyl acetate and reacted at 55°C for 8 hours under a nitrogen stream. Thereafter, ethyl acetate was added to the reaction liquid to obtain a solution of an acrylic polymer with a weight average molecular weight of 2.1 million. In this solution, a trimethylolpropane/toluene diisocyanate adduct ("Coronate L" manufactured by Tosoh): 0.6 parts by weight as a crosslinking agent and a silane coupling agent was blended with respect to 100 parts by weight of the polymer ("X-41-1056" manufactured by Shin-Etsu Chemical Industry) 0.2 parts by weight to obtain adhesive composition B.

(Adhesive composition R) In the reaction vessel, make BA: 92 parts by weight, N-acrylomorpholine (ACMO): 5 parts by weight, AA: 2.9 parts by weight, and 2HEA: 0.1 parts by weight as monomers, and AIBN: 0.1 parts by weight as polymerization The initiator was added together with ethyl acetate and reacted at 55°C for 8 hours under a nitrogen stream. Thereafter, ethyl acetate was added to the reaction solution to obtain a solution of acrylic polymer with a weight average molecular weight of 1.78 million. In this solution, Nyper BMT: 0.15 parts by weight and Coronate L: 0.6 parts by weight were blended as a crosslinking agent with respect to 100 parts by weight of the polymer to obtain an adhesive composition C.

＜Making of Adhesive Sheet＞ Apply the above-mentioned adhesive composition A to C on the release treatment surface of a 38 μm thick polyethylene terephthalate film (“MRF38” manufactured by Mitsubishi Chemical Co., Ltd.) after a release treatment, and dry at 150°C And cross-linking treatment to produce adhesive sheets with thicknesses of 5 μm, 10 μm, 15 μm, 20 μm, and 25 μm. Adhesive sheets made with adhesive composition P are used as adhesive sheets P1 to P5, adhesive sheets made with adhesive composition Q are used as adhesive sheets Q1 to Q5, and adhesive composition R is made The adhesive sheets are used as adhesive sheets R1 to R5.

[Experimental example A1] ＜Production of retardation film A＞ In a reaction vessel equipped with a stirring device, 2,2-bis(4-hydroxyphenyl)-4-methylpentane: 54 parts by weight, and benzyltriethylammonium chloride: 12 parts by weight were dissolved in 1 M in sodium hydroxide solution. While stirring this solution, a solution prepared by dissolving 406 parts by weight of chloroterephthalic acid in chloroform was added all at once, and stirred at room temperature for 90 minutes. Thereafter, the polymerization solution was allowed to stand still to separate, the chloroform solution containing the polymer was separated, followed by washing with acetic acid water, and washing with ion-exchanged water, and then poured into methanol to precipitate the polymer. The precipitated polymer was washed twice with distilled water and twice with methanol, and then dried under reduced pressure to obtain a polyarylate resin. The obtained polyarylate resin was dissolved in cyclopentanone to prepare a solution with a solid content of 20%.

Using a biaxially stretched polypropylene film as a support, the above solution was coated so that the film thickness after drying became 15 μm, and dried at 100°C to obtain a polyarylate resin layer laminated on the support film. Chengzhi layered body. The layered body was stretched in the conveying direction and contracted in the width direction using a roll stretcher. In the stretched polyarylate coating film (retardation film A) after the support film was peeled off, the thickness was 17 μm, the in-plane retardation at a wavelength of 550 nm was 250 nm, and the Nz coefficient was 0.5.

＜Production of polarizing plate＞ A biaxially stretched acrylic film with a thickness of 40 μm was applied to one surface of a polyvinyl alcohol-based polarizer with a thickness of 18 μm, and the retardation film A side of the laminate was bonded on the other surface with an ultraviolet curable adhesive. Laminating uses a roller laminator to irradiate ultraviolet rays to harden the adhesive. After that, the polypropylene film used as the support film was peeled off, and the adhesive sheet prepared above was laminated on the retardation film A side to obtain an acrylic film on one side of the polarizing element and a retardation film A on the other side , And an adhesive-attached polarizing plate with an adhesive layer on the side of the retardation film A.

＜Laminating facing the glass plate＞ The above-mentioned polarizing plate with adhesive was placed on an alkali-free glass plate with a thickness of 0.7 μm, and a pressure roller type single-piece laminating device was used to laminate at a lamination pressure of 0.3 MPa to obtain an evaluation sample.

[Experimental Example B1] Instead of retardation film A, a reduced olefin resin film (retardation film B) with a thickness of 132 μm, in-plane retardation of 250 nm, and Nz coefficient of 0.5 is used, and the polarizing plate with adhesive is applied in the same manner as above. Production and bonding facing the glass plate.

[Experimental example C1] A biaxially stretched olefin resin film (retardant film C) with a thickness of 18 μm, an in-plane retardation of 120 nm, and an Nz coefficient of 1.18 was used instead of the retardation film A. In the same manner as above, the adhesive was applied The production of polarizing plates and the bonding of facing glass plates.

[Evaluation] ＜Shear and storage modulus of adhesive film＞ For each of the adhesive sheets P3, Q3, and R3, 100 adhesive sheets were laminated to prepare a test sample. The sample was punched into a disc shape with a diameter of 7.9 mm and clamped by parallel plates. The "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific was used to perform dynamic viscoelasticity under the following conditions Measure and read the shear storage modulus at 25°C. (Measurement conditions) Deformation mode: twist Measuring frequency: 1 Hz Heating rate: 5℃/min Measuring temperature: -40～150℃

<The change of the retardation axis angle of retardation film relative to the value of tension> The retardation film is cut into short strips with a width of 10 mm at an angle of 45° with respect to the slow axis direction to the long side. On the measuring table of the polarized light and phase difference measuring system ("AxoScan" manufactured by Axometrics), fix one of the short sides of the short strip sample, and hang it vertically on the other short side to apply tension to the length of the sample. In this state, the in-plane retardation and the slow axis direction are measured. To change the mass of the vertical, plot the amount of change in the angle of the lagging axis with respect to the value of tension (the standard of the angle of the lagging axis when the tension is 0), and calculate the amount of change in the axis angle with respect to the slope of the straight line The value of tension (shaft change/tension).

<The amount of change in the optical axis of the polarizing plate> The angle θ ₀ between the absorption axis direction of the polarizing element in the optical film with adhesive and the slow axis direction of the retardation film is measured by the polarization and retardation measurement system. For the sample after bonding the optical film with the adhesive to the glass plate, measure the angle θ ₁ between the absorption axis direction of the polarizing element and the retardation axis direction of the retardation film to obtain the angle before and after bonding The absolute value of the difference (θ ₁ －θ ₀ ).

＜Fitting state＞ Visually observe whether there are bubbles in the bonding interface of the glass plate and the polarizing plate.

＜Optical unevenness＞ Place a standard polarizer (manufactured by Nitto Denko) on both sides of a polyvinyl alcohol-based polarizer with acrylic films as a transparent protective film, and place it on the tracking table, and place the glass plate of the evaluation sample on it Place it so that it becomes the bottom side. Two polarizing plates are arranged in such a way that the absorption axis direction of the standard polarizing plate is orthogonal to the absorption axis direction of the polarizing plate of the evaluation sample (cross-polarizer arrangement). By visually confirming the transmitted light from the tracking station, the unevenness is graded according to the following criteria. ○: Unidentified persons with unevenness (refer to Figure 3A) △: Some unevenness confirmed ×: If obvious unevenness is confirmed (refer to Figure 3B)

＜Evaluation result＞ Table 1 shows the thickness and optical properties of the retardation films A to C, the thickness D of the adhesive sheet, the shear storage modulus G'at 25°C, and the evaluation results of the bonded samples.

[Table 1] Retardation film Adhesive sheet Glass plate bonding products material Thickness (μm) Re (nm) ∆n (×10 ³ ) Nz Shaft change/tension (°/N/10 mm) D (μm) G'(kPa) G'/D (kPa/ μm) Axis change (°) bubble Uneven A Polyarylate 17 250 14.7 0.5 0.47 P1 5 81 16.2 0.08 no ○ P2 10 81 8.1 0.10 no ○ P3 15 81 5.4 0.2 no ○ P4 20 81 4.1 0.6 no X P5 25 81 3.2 1.0 no X Q1 5 120 24.0 0.05 no ○ Q2 10 120 12.0 0.08 no ○ Q3 15 120 8.0 0.10 no ○ Q4 20 120 6.0 0.15 no ○ Q5 25 120 4.8 0.5 no X R1 5 150 30.0 0.04 Have ○ R2 10 150 15.0 0.05 no ○ R3 15 150 10.0 0.05 no ○ R4 20 150 7.5 0.10 no ○ R5 25 150 6.0 0.2 no ○ B Norene 132 250 1.9 0.5 0.01 P4 20 81 4.1 0.05 no ○ P5 25 81 3.2 0.06 no ○ Q5 25 120 4.8 0.05 no ○ C Norene 18 120 6.7 1.2 0.01 P4 20 81 4.1 0.04 no ○ P5 25 81 3.2 0.05 no ○ Q5 25 120 4.8 0.05 no ○

It can be seen that the change in the retardation axis direction of the retardation films B and C is 0.01°/N/10 mm relative to the tension value. On the contrary, the retardation film A with larger birefringence has a relative change rate in the retardation axis direction The value of tension is larger.

In the polarizing plate formed by laminating polarizing elements on the retardation film A, before bonding to the glass plate, the slow axis direction of the retardation film is parallel to the absorption axis direction of the polarizing element (θ ₀ is 0.1° or less). After the polarizing plate with adhesive is attached to the glass plate, the axis deviation occurs, and it can be seen that the greater the thickness D of the adhesive sheet, and the smaller the shear storage modulus G', the greater the axis deviation. . In the sample using the adhesive sheet R1, unevenness was not confirmed, but mixing of air bubbles was seen at the bonding interface between the glass plate and the adhesive layer.

Even when the polarizing plate formed by laminating the retardation film B and the polarizing element is attached to the glass plate through the adhesive sheets P4, P5, Q5 with a large thickness and a small shear storage modulus G', it is not confirmed A clear axis offset is shown without unevenness. The same is true when the retardation film C is used.

[Experimental example A2] It is used for polarizing plate with an acrylic film on one side of the polarizing element, retardation film A on the other side, and an adhesive sheet P3 with a thickness of 15 μm on the area of the retardation film A side. As shown in Table 2, except that the lamination pressure was changed to the range of 0.01 to 1.0 MPa, in the same manner as in Experimental Example A1, the polarizing plate with the adhesive was attached to the alkali-free glass plate to obtain a test for evaluation kind.

[Experimental example B2] Use the polarizing plate with adhesive on the area layer on the B side of the retardation film with the adhesive sheet P3, except that the lamination pressure is changed to 0.7 Pa or 1.0 MPa, the same as in Experimental Example B1 Fitting of glass plates.

[Experimental example C2] Use the polarizing plate with adhesive on the area layer on the side of the retardation film C with the adhesive sheet P3, except that the lamination pressure is changed to 0.7 Pa or 1.0 MPa, and the same as the experimental example C1, the facing Fitting of glass plates.

[Evaluation] For each sample of Experimental Examples A2, B2, and C2, the variation of the optical axis, the bonding state, and the optical unevenness were evaluated. Table 2 shows the thickness and optical properties of the retardation films A to C, and the bonding conditions (laminating pressure) of the polarizing plate with the adhesive to the glass plate and the evaluation results.

[Table 2] Retardation film Glass plate bonding products material Thickness (μm) Re (nm) ∆n (×10 ³ ) Nz Shaft change/tension (°/N/10 mm) Laminating pressure (MPa) Axis change (°) bubble Uneven A Polyarylate 17 250 14.7 0.5 0.47 0.01 0.05 Have ○ 0.1 0.07 no ○ 0.3 0.1 no ○ 0.5 0.45 no △ 0.7 0.7 no × 1.0 1.1 no × B Norene 132 250 1.9 0.5 0.01 0.7 0.05 no ○ 1.0 0.05 no ○ C Norene 18 120 6.7 1.2 0.01 0.7 0.05 no ○ 1.0 0.05 no ○

It can be seen that in the polarizing plate with the adhesive which is formed by laminating the retardation film A and the polarizing element, the greater the lamination pressure when facing the glass plate, the greater the axis deviation tends to be. In the case of bonding at a lamination pressure of 0.5 MPa, unevenness was confirmed in the optical unevenness inspection, and if the lamination pressure was further increased, the unevenness became significant. In the sample bonded with the lamination pressure of 0.01 MPa, unevenness was not confirmed, but the mixing of bubbles can be seen in the bonding interface between the glass plate and the adhesive layer.

In the polarizing plate with adhesive which is formed by laminating retardation film B and polarizing element, even when the lamination pressure at the time of bonding with the glass plate was increased to 1.0 MPa, no clear axis deviation was confirmed , And did not produce unevenness. The same applies to the case of using retardation film C.

As mentioned above, in the sample made by laminating the polarizing element and the retardation film A on the glass plate, the thickness D of the adhesive sheet is larger, and the shear storage modulus G'is smaller (That is, when the adhesive sheet is thicker and softer), and when the lamination pressure at the time of lamination is large, the deviation of the optical axis of the retardation film becomes large, resulting in optical unevenness. On the other hand, in the polarizing plate formed by laminating the polarizing element and the retardation film B or the retardation film C, even if the type of the adhesive sheet or the lamination pressure is changed, no optical unevenness is observed.

Based on these results, it can be seen that the optical unevenness when bonding the polarizing plate with retardation film to the glass plate (the substrate of the image display unit) is a unique problem of the retardation film with large birefringence. The reason is Due to the deformation of the adhesive sheet during bonding, the axis shift of the retardation film occurs. It is considered that when a thinner and harder adhesive is used, or when the pressure during bonding is small, the deformation of the adhesive sheet is small, so the axis deviation of the retardation film is suppressed.

In Experimental Example A2, for the samples with obvious unevenness (the sample with the lamination pressure of 0.7 MPa and the sample with 1.0 MPa), the polarizing plate with the adhesive was peeled from the glass plate (secondary processing) Measure the angle difference θ ₂ between the slow axis direction of the retardation film and the absorption axis direction of the polarizing element, and the result is within 0.1°, and the axis offset is eliminated. In addition, the adhesive-attached polarizing plate after secondary processing was reattached to the glass plate at a lamination pressure of 0.3 MPa, and the presence or absence of optical unevenness was confirmed. As a result, unevenness was not confirmed.

Based on the above results, it is believed that the optical unevenness of the sample obtained by bonding the polarizing plate including the retardation film A and the polarizing element to the glass plate at a high lamination pressure is only due to the pressure during the bonding, which makes the adhesive sheet Deformation occurs, and the strain generated during deformation remains. By reducing the pressure during bonding, the strain is reduced, thereby preventing unevenness. In addition, it is believed that when an adhesive sheet with a small thickness and a small shear storage modulus is used, since the distortion caused by the deformation of the adhesive sheet is small, the axis deviation is not easy to occur, and the unevenness can be suppressed.

10: LCD unit 11: Liquid crystal layer 13: substrate 15: substrate 31: Polarizing element 33: Transparent protective film 34: Transparent protective film (phase difference film) 35: Transparent protective film (phase difference film) 36: Polarizing plate 37: Polarizing plate 39: Adhesive layer 51: Transparent protective film 53: Transparent protective film 55: Transparent protective film 56: Polarizing plate 59: Adhesive layer 70: Organic EL unit 71: organic light emitting layer 72: Transparent electrode 73: substrate 74: Metal electrode 100: LCD panel 105: light source 201: Liquid crystal display device 202: Organic EL display device

FIG. 1 is a cross-sectional view of the structure of a liquid crystal display device. 2 is a cross-sectional view of the structure of an organic EL display device. Fig. 3 is the cross-polarizer observation image of the sample formed by pasting the polarizing plate with adhesive and the glass plate. A is a sample with visually recognized unevenness, and B is a sample with no visually recognized unevenness.

10: LCD unit

11: Liquid crystal layer

13: substrate

15: substrate

31: Polarizing element

33: Transparent protective film

35: Transparent protective film (phase difference film)

36: Polarizing plate

39: Adhesive layer

51: Transparent protective film

53: Transparent protective film

55: Transparent protective film

56: Polarizing plate

59: Adhesive layer

100: LCD panel

105: light source

201: Liquid crystal display device

Claims (15)

An image display device is provided with an image display unit and a polarizing plate attached to the surface of the image display unit via an adhesive layer, and the polarizing plate has a polarizing element and a polarizing element arranged on one surface of the polarizing element A retardation film, the retardation film is arranged between the polarizing element and the image display unit, the retardation film has an in-plane birefringence of 8×10 ^-3 or more at a wavelength of 550 nm, and the polarizing plate passes through the In the state where the adhesive layer is attached to the image display unit, the angle θ ₁ formed by the slow axis direction of the retardation film and the absorption axis direction of the polarizing element and the polarizing plate from the image display unit The absolute value of the difference of the angle θ ₂ formed by the slow axis direction of the retardation film and the absorption axis direction of the polarizing element at the time of peeling |θ ₁ -θ ₂ | is 0.4° or less. The image display device of claim 1, wherein the retardation film, when tension is applied to the direction of 45° with respect to the slow axis direction, the amount of change with respect to the slow axis of tension is 0.1°/N/10 mm or more. The image display device of claim 1 or 2, wherein in the above-mentioned retardation film, the in-plane refractive index nx in the slow axis direction, the in-plane refractive index ny in the advancing axis direction, and the refractive index in the thickness direction nz Satisfy nx>nz>ny. Such as the image display device of claim 1 or 2, wherein the above θ ₁ is within the range of 0±0.4° or 90±0.4°. The image display device of claim 1 or 2, wherein the in-plane retardation of the retardation film is 200 nm or more. The image display device of claim 1 or 2, wherein the retardation film is in contact with the adhesive layer. The image display device of claim 1 or 2, wherein the shear storage modulus G'of the adhesive layer at a temperature of 25°C divided by the thickness D is a value G'/D of 5.0 kPa/μm or more. The image display device of claim 1 or 2, wherein the thickness of the adhesive layer is 25 μm or less. A method of manufacturing an image display device, which is manufactured on the surface of an image display unit, and an image display formed by bonding a polarizing plate with a polarizing element and a retardation film arranged on the surface of the polarizing element through an adhesive layer The method of the device is to prepare a retardation film with an area layer of a polarizing element that has an in-plane birefringence of 8×10 ^-3 or more at a wavelength of 550 nm, and an adhesive layer is attached to the retardation film. For the polarizing plate with adhesive, the above-mentioned polarizing plate with adhesive and the image display unit are bonded at a lamination pressure of 0.05 to 0.4 MPa. The method for manufacturing an image display device according to claim 9, wherein the shear storage modulus G'of the adhesive layer at a temperature of 25°C divided by the thickness D is a value G'/D of 5 kPa/μm or more. The method of manufacturing an image display device of claim 9 or 10, wherein the thickness of the adhesive layer is 25 μm or less. The method for manufacturing an image display device according to claim 9 or 10, wherein in the polarizing plate with adhesive, the angle θ ₀ , formed by the absorption axis direction of the polarizing element and the slow axis direction of the retardation film Absolute value of the difference between the angle θ ₁ formed by the retardation axis direction of the retardation film and the absorption axis direction of the polarizing element after the adhesive-attached polarizing plate and the image display unit are bonded together | θ ₁ －Θ ₀ | is 0.4° or less. The method for manufacturing an image display device according to claim 9 or 10, wherein the in-plane retardation of the retardation film is 200 nm or more. The method for manufacturing an image display device according to claim 9 or 10, wherein the retardation film, when tension is applied to the direction of 45° with respect to the slow axis direction, the amount of change with respect to the slow axis of tension is 0.1°/N /10 mm or more. The method for manufacturing an image display device according to claim 9 or 10, wherein in the above-mentioned retardation film, the refractive index nx in the direction of the slow axis in the plane, the refractive index ny in the direction of the advancing axis in the plane, and the thickness direction The refractive index nz satisfies nx>nz>ny.

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