CN111869324B - Electroluminescent display device - Google Patents

Abstract

An electroluminescent display device, comprising: an electroluminescent element, and a circularly polarizing plate disposed on the visual side of the electroluminescent element, wherein the circularly polarizing plate comprises a retardation layer, a polarizing plate, and a base film in this order, (1) the base film has an in-plane retardation of 3000 to 30000nm, (2) there is no free-standing film between the polarizing plate and the retardation layer, or there is only 1 free-standing film (the retardation layer itself is included between the polarizing plate and the retardation layer), and (3) the retardation layer comprises a 1/2 wavelength layer and a 1/4 wavelength layer.

Description

Electroluminescent display device

Technical field

The present invention relates to electroluminescent (EL) display devices.

Background technique

In an EL display device, there is a problem that external light is reflected on the surface of the component materials such as image display elements and touch sensors, and on these wiring portions, thereby reducing visibility. In order to solve these problems, a method has been proposed to reduce the reflection of external light by arranging an optical laminate on the exit surface of the image display device. This optical laminate usually uses a circularly polarizing plate in which a linear polarizing plate and a quarter-wavelength retardation plate are laminated.

As a polarizing plate protective film for a polarizing plate, a polyester film having an in-plane retardation of 3000 to 30000 nm has been proposed (for example, see Patent Document 1). Compared with cellulose-based or acrylic-based films, polyester films have lower moisture permeability, excellent mechanical properties (high impact resistance and high elastic modulus), and further excellent chemical properties (solvent resistance, etc.), so they are suitable for use. in image display devices. However, the polyester film has birefringence and therefore has the disadvantage of easily generating iris spots. Therefore, in order to use a polyester film, suppress iris spots and provide sufficient in-plane retardation, the film needs to be thickened.

Furthermore, in order to suppress the influence of the wavelength dispersion of the refractive index and obtain a circularly polarizing plate with better color reproducibility, a technology that combines a quarter-wavelength plate and a half-wavelength plate has been proposed (Patent Document 2). However, when a plurality of such phase difference plates are stacked on a polarizing plate, the above-mentioned thickness problem becomes more obvious. In addition, the circularly polarizing plate is laminated with a plurality of films. Therefore, when the circularly polarizing plate is rolled up and stored during the manufacturing process, it is prone to curling, which may make it difficult to handle in the subsequent bonding process with the EL element. Especially in large image display devices such as those exceeding the 40-inch type (the diagonal length of the display section is 40 inches), the circular polarizing plate also becomes larger, and the problem of curling is likely to occur.

In addition, in recent years, flexible image display devices have been proposed that have a wide display surface and can be folded into a V-shape, Z-shape, W-shape, double-door shape, etc. when carried, or can be rolled into a roll. EL display device. If a circular polarizing plate is used in such a foldable (foldable) or rollable (rollable) EL display device, there are problems such as insufficient bending performance cannot be obtained due to its thickness; repeated bending operations or placement on In high-temperature places such as the interior of a car, the film is easily peeled off and is prone to bend marks and other problems.

existing technical documents

patent documents

Patent Document 1: Japanese Patent Application Publication No. 2012-256057

Patent document 2: Japanese Patent Application Laid-Open No. 10-68816

Contents of the invention

Invent the problem to be solved

The present invention was made against the background of the above-mentioned prior art problems. That is, an object of the present invention is to provide a member that can be thinned while ensuring visibility, is less likely to cause trouble in the manufacturing process, and is a flexible EL display device that can be laminated when repeatedly bent or left in a high temperature state. An EL display device that is not easily peeled off or creased.

solutions to problems

In order to develop a flexible EL display device that can be thinned while ensuring visibility and is less likely to cause trouble in the manufacturing process, the laminated members cannot be bent repeatedly or placed in a high temperature state. As a result of in-depth research on EL display devices that are less likely to be peeled off and less prone to creases, it was found that using a base film with a specific in-plane retardation can make the self-standing film between the polarizer and the retardation layer more flexible. The above object can be achieved by using a circularly polarizing plate having a 1/2 wavelength layer and a 1/4 wavelength layer as a phase difference plate with a quantity of 1 or less. The present invention was completed based on such findings.

That is, the present invention relates to the EL display device shown in Items 1 to 4.

Item 1.

An electroluminescent display device, which is provided with: an electroluminescent element, and a circular polarizing plate arranged closer to the visible side than the electroluminescent element,

The aforementioned circular polarizing plate has a phase difference layer, a polarizing plate and a base film in sequence,

(1) The in-plane retardation of the base film is 3000~30000nm;

(2) There is no self-standing film between the polarizing plate and the retardation layer, or there is only one self-standing film (the retardation layer itself is also included between the polarizing plate and the retardation layer); and,

(3) The phase difference layer has a 1/2 wavelength layer and a 1/4 wavelength layer.

Item 2.

The electroluminescent display device according to the above item 1, wherein the thickness of the polarizing plate is 12 μm or less.

Item 3.

The electroluminescent display device according to the above item 1 or 2, wherein the polarizing plate is formed of a polymerizable liquid crystal compound and a dichroic dye.

Item 4.

The electroluminescent display device according to any one of the above items 1 to 3, wherein at least one of the 1/2 wavelength layer and the 1/4 wavelength layer is formed of a liquid crystal compound.

Effect of the invention

The EL display device of the present invention uses a base film with an in-plane retardation of 3000 to 30000 nm, sets the number of self-standing films between the polarizing plate and the retardation layer to one or less, and uses a 1/2 wavelength layer and Since the circularly polarizing plate of the 1/4 wavelength layer serves as the retardation layer, it has excellent visibility (suppression of rainbow spots), can be thinned, and is less likely to cause trouble in the manufacturing process.

In addition, in the case of a flexible EL display device, the laminated members are not easily peeled off from each other after being repeatedly bent or left in a high-temperature state, and are less likely to be creased.

Detailed ways

The EL display device of the present invention includes an EL element and a circular polarizing plate arranged closer to the viewing side than the EL element. By arranging the circular polarizing plate on the visible surface of the EL display device, it is possible to reduce visibility degradation caused by external light reflected on the EL element surface or wiring. In addition, the EL display device of the present invention is thin. The circularly polarizing plate has a phase difference layer, a polarizing plate and a base film in sequence.

First, the circularly polarizing plate used in the present invention will be described. The circularly polarizing plate has a retardation layer, a polarizing plate and a base film in sequence. In this circularly polarizing plate, the retardation layer, the polarizing plate, and the base film are basically laminated in order, but this concept also includes the case where another layer exists between each layer.

A.Circular polarizing plate

1.Substrate film

First, the base film of the circularly polarizing plate will be described. This circularly polarizing plate has a base film on the visible side of the polarizing plate.

(Material of base film)

The resin of the base film used in the present invention can be used without particular limitation as long as it generates birefringence due to orientation. Since the retardation amount can be increased, polyester, polycarbonate, polystyrene, etc. are preferable, and polyester is more preferable. Preferred polyesters include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polynaphthalenedicarboxylic acid. Ethylene glycol ester (PEN) and the like, among which PET and PEN are more preferred. By using a polyester film as the base film, an EL display device having a circularly polarizing plate excellent in moisture permeability resistance, dimensional stability, mechanical strength, and chemical stability can be obtained.

In the case of PET, the intrinsic viscosity (IV) of the resin constituting the base film is preferably 0.58 to 1.5 dL/g. The lower limit of IV is more preferably 0.6dL/g, further preferably 0.65dL/g, and particularly preferably 0.68dL/g. The upper limit of IV is more preferably 1.2 dL/g, further preferably 1 dL/g. If the IV of PET is less than 0.58 dL/g, bending marks may be easily formed by repeated bending. If the IV of PET exceeds 1.5 dL/g, film production may become difficult. In addition, as the intrinsic viscosity (IV) in the present invention, a value obtained by mixing phenol and 1,1,2,2-tetrachloroethane as a solvent in a mass ratio of 6:4 is used. , and the value measured at a temperature of 30°C.

The light transmittance of the base film at a wavelength of 380 nm is desirably 20% or less. The light transmittance at a wavelength of 380 nm is more preferably 15% or less, further preferably 10% or less, and particularly preferably 5% or less. If the light transmittance is 20% or less, it is possible to suppress deterioration of iodine or dichroic dyes in the polarizing plate due to ultraviolet rays. It should be noted that the transmittance in the present invention is measured in a direction perpendicular to the plane of the film, and can be measured using a spectrometer (for example, Hitachi U-3500 model).

In order to make the light transmittance of the base film at a wavelength of 380 nm 20% or less, it can be achieved by the following methods: adding an ultraviolet absorber to the base film; applying a coating liquid containing the ultraviolet absorber to the surface of the base film ; Suitably adjust the type or concentration of ultraviolet absorber and the thickness of the base film; etc. In the present invention, substances known in the technical field can be used as ultraviolet absorbers. Examples of ultraviolet absorbers include organic ultraviolet absorbers and inorganic ultraviolet absorbers. From the viewpoint of transparency, organic ultraviolet absorbers are preferred.

The organic ultraviolet absorber can be used without particular limitation as long as it can reduce the light transmittance of the base film at a wavelength of 380 nm to 20% or less. Examples of such organic ultraviolet absorbers include benzotriazole-based, benzophenone-based, cyclic iminoester-based, and the like, and combinations thereof.

In addition, in order to improve the sliding properties of the base film, it is preferable to add particles with an average particle diameter of 0.05 to 2 μm. Examples of particles include titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, calcium phosphate, mica, hectorite, zirconium oxide, tungsten oxide, and lithium fluoride. , calcium fluoride and other inorganic particles; styrene, acrylic, melamine, benzoguanamine, silicone and other organic polymer particles, etc. The average particle diameter is calculated by observing particles in a cross section of the film using a scanning electron microscope. Specifically, 100 particles in the cross section of the film were observed using a scanning electron microscope, the diameter (d) of each particle was measured, and their average value was used as the average particle diameter.

These particles can be added to the entire base film. Alternatively, the substrate can also be formed into a skin-core co-extruded multilayer structure, with particles added only to the skin layer.

(In-plane retardation of base film)

The base film has an in-plane retardation of 3000 to 30000 nm. One of the features of the EL display device of the present invention is to use a substrate film having an in-plane retardation of 3000 to 30000 nm as a circular polarizing plate. If the in-plane retardation of the base film is less than 3000 nm, good visibility may not be ensured when viewed from an oblique direction with respect to the normal direction. In addition, when the in-plane retardation of the base film is less than 3000 nm for the purpose of preventing dizziness or coloration when observing images with polarized sunglasses, rainbow spots may be observed. A preferable lower limit of the in-plane retardation is 4500 nm, and a more preferable lower limit is 6000 nm.

On the other hand, the upper limit of the in-plane retardation is preferably 30,000 nm. Even if the base film has a retardation exceeding the above, substantially no further improvement effect on visibility can be obtained, and the thickness of the base film becomes considerably thicker, thereby reducing the handleability as an industrial material. In order to reduce the thickness of the film and ensure thinning or flexibility, the upper limit of the in-plane retardation is more preferably 15,000 nm or less, further preferably 11,000 nm, and particularly preferably 9,000 nm or less.

The retardation of the base film can be determined by measuring the refractive index and thickness in the biaxial direction, or can be determined using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Scientific Instruments Co Ltd.). In addition, the refractive index is a value measured at the wavelength of sodium D ray (589 nm).

For the base film, the ratio of the in-plane retardation (Re) to the thickness direction retardation (Rth) is preferably within a specific range. The thickness direction retardation refers to the average retardation obtained by multiplying two birefringences (ΔNxz and ΔNyz) by the film thickness d when the film is viewed cross-sectionally in the thickness direction. The smaller the difference between the in-plane retardation and the thickness direction retardation, the more isotropic the effect of birefringence due to the observation angle, and therefore the change in the retardation due to the observation angle becomes smaller. Therefore, it is considered that rainbow-shaped color spots caused by the viewing angle become less likely to occur.

The ratio of the in-plane retardation to the thickness direction retardation (Re/Rth) of the base film is preferably 0.2 or more, more preferably 0.5 or more, and still more preferably 0.6 or more. The greater the ratio of the above-mentioned in-plane retardation to the thickness direction retardation (Re/Rth), the more isotropic the effect of birefringence, making it less likely to cause iridescent color spots depending on the viewing angle. Furthermore, in a completely uniaxial (uniaxially symmetric) film, the ratio of the above-mentioned in-plane retardation to the thickness direction retardation (Re/Rth) becomes 2. However, as mentioned above, as the film approaches a complete uniaxiality (uniaxial symmetry), the mechanical strength in the direction orthogonal to the orientation direction significantly decreases.

On the other hand, the ratio of the in-plane retardation to the thickness direction retardation (Re/Rth) of the base film is preferably 1.5 or less, more preferably 1.2 or less, and still more preferably 1 or less. In order to completely suppress the occurrence of rainbow-shaped color spots due to the observation angle, the ratio of the above-mentioned in-plane retardation amount to the thickness direction retardation amount (Re/Rth) does not need to be 2, and it is sufficient to be 1.5 or less, or 1.2 or less. In addition, if the above ratio is 1 or less, the viewing angle characteristics required for the EL display device (approximately 180 degrees left and right, and approximately 120 degrees up and down) can be fully satisfied.

(Nz coefficient)

The base film preferably has an Nz coefficient represented by |ny-nz|/|ny-nx| of 1.7 or less. The Nz coefficient can be found as follows. The orientation axis direction of the film was determined using a molecular orientation meter (MOA-6004 molecular orientation meter manufactured by Oji Scientific Instruments Co Ltd.), and the wavelength was measured using an Abbe refractometer (NAR-4T manufactured by ATAGO CO., LTD. 589nm), the refractive index (ny, nx, where ny>nx) of the biaxial direction of the orientation axis and the direction orthogonal thereto, and the refractive index (nz) of the thickness direction were obtained. The Nz coefficient can be obtained by substituting the nx, ny and nz obtained in this way into the equation shown by |ny-nz|/|ny-nx|.

If the Nz coefficient of the base film exceeds 1.7, when the EL display device is viewed from an oblique direction, rainbow spots may occur depending on the angle. The Nz coefficient is more preferably 1.65 or less, further preferably 1.63 or less. The lower limit of Nz coefficient is 1.2. This is because it is difficult to obtain a film with an Nz coefficient lower than 1.2 due to manufacturing technology. In addition, in order to maintain the mechanical strength of the film, the lower limit value of the Nz coefficient is preferably 1.3 or more, more preferably 1.4 or more, and still more preferably 1.45 or more.

(degree of plane orientation)

The base film preferably has a plane orientation degree represented by (nx+ny)/2-nz that is equal to or less than a specific value. Here, the values of nx, ny, and nz can be obtained using the same method as the Nz coefficient. The degree of plane orientation of the base film is preferably 0.13 or less, more preferably 0.125 or less, and even more preferably 0.12 or less. If the plane orientation degree exceeds 0.13, rainbow spots may be observed depending on the angle when the EL display device is viewed from an oblique direction. If the plane orientation degree is less than 0.08, the film thickness may fluctuate, and the retardation value may become uneven within the film surface.

(Method for manufacturing base film)

By stretching the film serving as the base material, a predetermined in-plane retardation can be provided. As long as the properties can be obtained by stretching, it may be uniaxial stretching or biaxial stretching. The slow axis of the base film may be the length direction of the base film, a direction orthogonal to the length direction, or an oblique direction. It should be noted that the length direction here refers to the traveling direction when the film is continuously produced. The angle between the longitudinal direction of the base film and the slow axis is preferably 10 degrees or less, and particularly preferably 7 degrees or less when the slow axis is the longitudinal direction of the base film. When the slow axis of the base film is perpendicular to the longitudinal direction, the angle between the longitudinal direction of the base film and the slow axis is preferably 80 to 100 degrees, particularly preferably 83 to 97 degrees. When the slow axis of the base film is in an inclined direction, the angle between the longitudinal direction of the base film and the slow axis is preferably in the range of 35 to 55 degrees.

Taking a PET base film having a slow axis in a direction orthogonal to the longitudinal direction as an example, the stretching conditions will be specifically explained.

The melted PET is extruded onto a cooling roll, and both ends of the resulting unstretched billet are fixed with clamps and introduced into a tenter. After preheating, the billet is stretched in the transverse direction while heating. It should be noted that before stretching in the transverse direction, a continuous roller can be used to stretch in the longitudinal direction. In addition, simultaneous biaxial stretching can also be performed. The longitudinal stretching temperature and the transverse stretching temperature are preferably 80 to 130°C, particularly preferably 90 to 120°C. The longitudinal stretch ratio is preferably 1 to 3.5 times, and particularly preferably 1 to 3 times. In addition, the transverse stretch ratio is preferably 2.5 to 6 times, and particularly preferably 3 to 5.5 times. In order to control the retardation amount within the above range, it is preferable to control the ratio of the longitudinal draw ratio and the transverse draw ratio. If the difference between the longitudinal and transverse stretch ratios is too small, it becomes difficult to increase the retardation amount. In addition, setting the stretching temperature low is a preferable solution in terms of increasing the retardation amount. In the subsequent heat treatment, the treatment temperature is preferably 100 to 250°C, particularly preferably 180 to 245°C.

In order to obtain a base film having a slow axis in the longitudinal direction, it is preferable to perform longitudinal stretching using a continuous roll. Before the longitudinal stretching process, transverse stretching may also be performed.

In addition, the angle between the main orientation axis of the base film and the longitudinal direction or a direction orthogonal to the longitudinal direction is preferably 20 degrees or less, more preferably 15 degrees or less, further preferably 10 degrees or less, and particularly preferably 5 degrees or less. If the angle between the main orientation axis of the base film and the longitudinal direction or a direction orthogonal to the longitudinal direction exceeds 20 degrees, the change in brightness due to the angle will become larger when viewed through polarized sunglasses or the like. It should be noted that when stretching in the longitudinal direction, the main orientation direction becomes the longitudinal direction. Therefore, let the angle between the main axis of the main orientation and the longitudinal direction be the angle. When stretching in the width direction, let it be the main angle. The angle between the main axis of orientation and the direction orthogonal to the length direction.

The thickness of the base film is preferably 30 to 150 μm, more preferably 40 to 100 μm, and even more preferably 50 to 80 μm. When the thickness of the base film is less than 30 μm, it becomes difficult to achieve a high in-plane retardation. When it exceeds 150 μm, handling becomes difficult and it becomes difficult to cope with thinning or ensure flexibility.

The base film can be subjected to treatments such as corona treatment, flame treatment, and plasma treatment to improve adhesion.

(Easy bonding layer)

In order to improve the adhesiveness with a polarizing film or an alignment layer described later, an easy-adhesion layer (easy-adhesion layer P1) may be provided on the base film.

Examples of the resin used in the easy-adhesion layer include polyester resin, polyurethane resin, polyester urethane resin, polycarbonate resin, polycarbonate urethane resin, acrylic resin, and the like. Among these, polyester resin, Polyester urethane resin, polycarbonate urethane resin and acrylic resin. The easy-adhesion layer is preferably crosslinked. Examples of crosslinking agents include isocyanate compounds, melamine compounds, epoxy resins, and oxazoline compounds. In addition, in order to improve the adhesion, it is also useful to add resins similar to those used in the alignment layer or polarizing film, such as polyvinyl alcohol, polyamide, polyimide, and polyamide-imide.

The easy-adhesion layer can be provided by forming a water-based paint to which these resins, crosslinking agents, particles, etc. are added as necessary, and then being applied to a base film and dried. Examples of particles include users of the above base materials.

The easy-adhesion layer may be provided on the stretched base film offline, or may be provided online during the film production process. The easy-adhesion layer is preferably provided in-line during the film forming process. When the easy-adhesion layer is provided on the line, it may be before longitudinal stretching or before transverse stretching. Particularly preferably, the water-based paint is applied immediately before transverse stretching, preheated and heated using a tenter, and dried and cross-linked in the heat treatment step to provide an easy-adhesion layer online. In addition, when in-line coating is performed using a roller immediately before longitudinal stretching, it is preferable to apply the aqueous coating material, dry it in a vertical dryer, and then introduce it to a stretching roller.

The coating amount of the water-based paint is preferably 0.01 to 1.0 g/m ² , more preferably 0.03 to 0.5 g/m ² .

(functional layer)

It is also a preferred embodiment to provide functional layers such as a hard coat layer, an anti-reflection layer, a low-reflection layer, an anti-glare layer, and an antistatic layer on the side of the base film opposite to the surface on which the polarizing film is laminated.

The thickness of these functional layers can be set appropriately, but is preferably 0.1 to 50 μm, more preferably 0.5 to 20 μm, and even more preferably 1 to 10 μm. It should be noted that these layers can have multiple layers.

When providing a functional layer, an easy-adhesion layer (easy-adhesion layer P2) may be provided between the functional layer and the base film. In the easy-adhesion layer P2, the resin, crosslinking agent, etc. mentioned in the said easy-adhesion layer P1 can be suitably used. In addition, the easy-adhesion layer P1 and the easy-adhesion layer P2 may have the same composition or may have different compositions.

The easy-adhesion layer P2 is also preferably provided in-line. The easy-adhesion layer P1 and the easy-adhesion layer P2 can be formed by sequentially applying and drying. In addition, it is also a preferred method to simultaneously coat the easy-adhesion layer P1 and the easy-adhesion layer P2 on both sides of the base film.

In the following description, the term "base film" includes not only the case where the easy-adhesion layer is not provided, but also the case where the easy-adhesion layer is provided. Similarly, those provided with functional layers are also included in the base film.

2.Polarizer

In the circularly polarizing plate used in the present invention, a polarizing plate is provided on the base film.

As the polarizing plate, for example, a polarizing film can be used. The polarizing film may be directly provided on the base film, or an alignment layer may be provided on the base film and the polarizing film may be provided on the base film. It should be noted that in the present invention, the alignment layer and the polarizing film may be collectively referred to as a polarizing plate. In addition, when the orientation layer is not provided on the base film but a polarizing film is provided, the polarizing film can be called a polarizing plate.

(Polarizing film)

The polarizing film has the function of allowing polarized light to pass only in one direction. The polarizing film can be used without particular limitation: a stretched film such as polyvinyl alcohol (PVA) containing iodine or a dichroic pigment, a dichroic pigment film or a polymerizable liquid crystal compound containing a dichroic pigment Coating films obtained from pigments, polyene stretched films, wire grids, etc.

Among them, a polarizing film in which iodine is adsorbed into PVA and a polarizing film in which a dichroic dye is blended into a polymerizable liquid crystal compound are preferred examples.

First, a polarizing film in which iodine is adsorbed in PVA will be described.

A polarizing film with iodine adsorbed in PVA can usually be obtained by immersing an unstretched PVA film in a bath containing iodine and then uniaxially stretching it, or by immersing the uniaxially stretched film in a bath containing iodine, and then It can be obtained by cross-linking in a boric acid bath.

The thickness of the polarizing film obtained by the above method is preferably 1 to 30 μm, more preferably 1.5 to 20 μm, and even more preferably 2 to 15 μm. If the thickness of the polarizing film is less than 1 μm, sufficient polarizing characteristics cannot be expressed, and if it is too thin, it may become difficult to handle. If the thickness of the polarizing film exceeds 30 μm, it does not meet the purpose of being thin or ensuring flexibility.

When laminating a polarizing film in which iodine is adsorbed into PVA and a base film, it is preferable to bond the base film and the polarizing film. As an adhesive for pasting, it can be used by existing users without restrictions. Among these, PVA-based aqueous adhesives, ultraviolet curable adhesives, etc. are preferred examples, and ultraviolet curable adhesives are more preferred.

In this way, the polarizing film in which iodine is adsorbed in PVA can be used as a separate film as a polarizing plate and can be laminated with the base film. Alternatively, it may be laminated by using a method in which a mold-releasing support base material is coated with PVA and stretched in this state, and a polarizing plate is laminated on the mold-releasing supporting base material (mold-releasing supporting base material). Support the base material and stack the polarizing film), and transfer the polarizing film to the base film. This method of laminating by transfer is also preferable as a method of laminating the polarizing plate and the base film, as is the above-mentioned method of pasting. When this transfer method is used, the thickness of the polarizing plate is preferably 12 μm or less, more preferably 10 μm or less, further preferably 8 μm or less, and particularly preferably 6 μm or less. Even such a very thin polarizing plate is easy to handle because it is a releasable supporting base material, and the polarizing plate can be easily laminated on the base film. By using such a thin polarizing plate, it is possible to further reduce the thickness and ensure flexibility.

In addition, the technique of laminating a polarizing plate and a base film is well-known, for example, it can refer to Japanese Patent Application Laid-Open No. 2001-350021, Japanese Patent Application Laid-Open No. 2009-93074, etc.

A method of laminating a polarizing plate and a base film by transfer will be specifically described. First, PVA is coated on a thermoplastic resin release support base material that is unstretched or uniaxially stretched perpendicularly to the length direction, and the resulting thermoplastic resin release support base material is placed along the laminate of PVA. The length direction is stretched to 2 to 20 times, preferably 3 to 15 times. The stretching temperature is preferably 80 to 180°C, more preferably 100 to 160°C. Next, the stretched laminate is immersed in a bath containing a dichroic dye to adsorb the dichroic dye. Examples of dichroic dyes include iodine, organic dyes, and the like. When using iodine as a dichroic dye, it is preferable to use an aqueous solution containing iodine and potassium iodide as a dyeing bath. Next, it is immersed in an aqueous solution of boric acid for treatment, washed with water, and then dried. It should be noted that before adsorption of the dichroic dye, stretching of 1.5 to 3 times may be performed as pre-stretching. It should be noted that the above method is an example, and the dichroic dye may be adsorbed before stretching, or treatment with boric acid may be performed before the dichroic dye is adsorbed. Stretching may also be performed in a bath containing a dichroic dye or in a bath containing a boric acid aqueous solution. In addition, these steps can be divided into multiple stages and performed in combination.

As the releasable support base material (release film) for the thermoplastic resin, polyester films such as polyethylene terephthalate, polyolefin films such as polypropylene and polyethylene, polyamide films, polyurethane films, and the like can be used. The release force of the thermoplastic resin releasable support base material (release film) can be adjusted by corona treatment, release coating, easy-adhesion coating, etc.

A laminate of a base film and a polarizing plate can be obtained by pasting the polarizing plate surface of the polarizing plate laminated on the releasable supporting base material to the base film with an adhesive or an adhesive agent, and then peeling off the releasable supporting base material. . The thickness of adhesives commonly used is 5 to 50 μm, while adhesives are 1 to 10 μm. In order to reduce the thickness, it is preferable to use an adhesive, and among these, it is more preferable to use an ultraviolet curable adhesive. It is also preferable to use an adhesive from the viewpoint of a process that does not require special equipment.

Next, a polarizing film in which a dichroic dye is blended into a polymerizable liquid crystal compound will be described.

A dichroic dye is a dye having a property in which the absorbance in the long axis direction of the molecule is different from the absorbance in the short axis direction.

The dichroic dye preferably has an absorption maximum wavelength (λMAX) in the range of 300 to 700 nm. Examples of such dichroic dyes include organic dichroic dyes such as acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes. Among them, azo dyes are preferred. Examples of azo dyes include monoazo dyes, disazo dyes, trisazo dyes, tetrasazo dyes, and stilbeneazo dyes. Among them, disazo dyes and trisazo dyes are preferred. The dichroic pigments may be used alone or in combination. In order to adjust the (achromatic) color tone, it is preferable to combine two or more types, and it is more preferable to combine three or more types. It is particularly preferable to use three or more azo compounds in combination.

Preferable azo compounds include dyes described in Japanese Patent Application Laid-Open Nos. 2007-126628, 2010-168570, 2013-101328, 2013-210624, etc. .

It is also a preferred embodiment that the dichroic dye is a dichroic dye polymer introduced into a side chain of a polymer such as acrylic. Examples of these dichroic dye polymers include polymers listed in Japanese Patent Application Laid-Open No. 2016-4055 and polymers obtained by polymerizing compounds [Chemical 6] to [Chemical 12] in Japanese Patent Laid-Open No. 2014-206682. of polymers, etc.

The content of the dichroic dye in the polarizing film is preferably 0.1 to 30 mass%, more preferably 0.5 to 20 mass%, and even more preferably 1.0 to 15 mass% in the polarizing film from the viewpoint of improving the orientation of the dichroic dye. %, particularly preferably 2.0 to 10% by mass.

In order to improve film strength, polarization degree, film homogeneity, etc., the polarizing film contains a polymerizable liquid crystal compound. It should be noted that the polymerizable liquid crystal compound also includes those polymerized in the form of a film.

A polymerizable liquid crystal compound refers to a compound that has a polymerizable group and exhibits liquid crystallinity.

The polymerizable group refers to a group that participates in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can undergo a polymerization reaction by an active radical generated by a photopolymerization initiator described below, an acid, or the like. Examples of the polymerizable group include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, and ethylene oxide groups. , oxetanyl, etc. Among these, an acryloxy group, a methacryloyloxy group, an vinyloxy group, an oxirane group, and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The compound exhibiting liquid crystallinity may be a thermotropic liquid crystal or a lyotropic liquid crystal, and may be a nematic liquid crystal or a smectic liquid crystal among the thermotropic liquid crystals.

In terms of obtaining higher polarization characteristics, the polymerizable liquid crystal compound is preferably a smectic liquid crystal compound, and more preferably a higher-order smectic liquid crystal compound. If the liquid crystal phase formed by the polymerizable liquid crystal compound is a higher-order smectic phase, a polarizing film with higher orientation order can be produced.

Specific examples of preferred polymerizable liquid crystal compounds include Japanese Patent Application Laid-Open No. 2002-308832, Japanese Patent Application Laid-Open No. 2007-16207, Japanese Patent Application Laid-Open No. 2015-163596, and Japanese Patent Application Publication No. 2007-510946. , substances described in Japanese Patent Application Publication No. 2013-114131, WO2005/045485, Lub et al. Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996), etc.

From the viewpoint of improving the orientation of the polymerizable liquid crystal compound, the content ratio of the polymerizable liquid crystal compound in the polarizing film is preferably 70 to 99.5% by mass, more preferably 75 to 99% by mass, and even more preferably 80 to 97% by mass. %, particularly preferably 83 to 95% by mass.

A polarizing film containing a polymerizable liquid crystal compound and a dichroic dye can be formed by coating the polarizing film composition.

In addition to the polymerizable liquid crystal compound and the dichroic dye, the polarizing film composition may further include a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a cross-linking agent, and the like.

As the solvent, any solvent can be used without limitation as long as it dissolves the polymerizable liquid crystal compound. Specific examples of the solvent include water; alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, ethylene glycol, propylene glycol, and cellosolve; and ester-based solvents such as ethyl acetate, butyl acetate, and γ-butyrolactone. ; Ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone; aromatic hydrocarbon solvents such as toluene and xylene; ether solvents such as tetrahydrofuran and dimethoxyethane, etc. These solvents can be used alone or in combination.

The polymerization initiator can be used without limitation as long as it polymerizes the polymerizable liquid crystal compound. As the polymerization initiator, a photopolymerization initiator that generates active radicals by light is preferred. Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts, sulfonium salts, and the like.

As the sensitizer, a photosensitizer is preferred. Examples of the photosensitizer include xanthone compounds, anthracene compounds, phenothiazine, rubrene, and the like.

Examples of polymerization inhibitors include hydroquinones, catechols, and thiophenols.

Examples of the leveling agent include various known surfactants.

As the polymerizable non-liquid crystal compound, one copolymerized with a polymerizable liquid crystal compound is preferred. For example, when the polymerizable liquid crystal compound has a (meth)acryloyloxy group, examples of the polymerizable non-liquid crystal compound include (meth)acrylates. (Meth)acrylates may be monofunctional or polyfunctional. By using polyfunctional (meth)acrylates, the strength of the polarizing film can be improved. When using a polymerizable non-liquid crystal compound, it is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and even more preferably 3 to 7% by mass in the polarizing film. If the content of the polymerizable non-liquid crystal compound exceeds 15% by mass, the degree of polarization may decrease.

Examples of the crosslinking agent include compounds capable of reacting with functional groups of polymerizable liquid crystal compounds and polymerizable non-liquid crystal compounds. Specific examples of the crosslinking agent include isocyanate compounds, melamine, epoxy resins, and oxazoline compounds.

A polarizing film can be provided by directly applying the composition for a polarizing film onto a base film or an alignment layer, drying it as necessary, and heating and curing the composition.

As the coating method, known methods such as coating methods such as gravure coating, die coating, rod coating, and applicator methods; and printing methods such as the flexographic method can be used.

Drying is performed as follows: introducing the coated base film into a hot air dryer, an infrared dryer, etc., and performing the drying at preferably 30 to 170°C, more preferably 50 to 150°C, and even more preferably 70 to 130°C. The drying time is preferably 0.5 to 30 minutes, more preferably 1 to 20 minutes, even more preferably 2 to 10 minutes.

Heating can be performed in order to orient the dichroic dye and the polymerizable liquid crystal compound in the polarizing film more firmly. The heating temperature is preferably a temperature range in which the polymerizable liquid crystal compound forms a liquid crystal phase.

Since the composition for polarizing films contains a polymerizable liquid crystal compound, it is preferable to harden it. Examples of curing methods include heating and light irradiation, and light irradiation is preferred. The dichroic dye can be fixed in a state in which the dichroic dye is oriented by curing. The curing is preferably performed in a state where a liquid crystal phase is formed in the polymerizable liquid crystal compound. Alternatively, the polymerizable liquid crystal compound may be cured by irradiating light at a temperature at which the liquid crystal phase is expressed.

Examples of light used in light irradiation include visible light, ultraviolet light, laser beam, etc. In terms of ease of operation, ultraviolet light is preferred.

The irradiation intensity varies depending on the type or amount of the polymerization initiator or resin (monomer). For example, it is preferably 100 to 10000 mJ/cm ² based on 365 nm, and more preferably 200 to 5000 mJ/cm ² .

Polarizing Film The polarizing film composition is applied to an alignment layer provided as necessary, so that the pigment is oriented along the alignment direction of the alignment layer. As a result, the polarizing film has a polarized light transmission axis in a predetermined direction. When the polarizing film composition is directly applied to the base material without providing an alignment layer, the polarizing film can be oriented by irradiating polarized light to cure the polarizing film composition. It is further preferable to perform heat treatment afterwards so that the dichroic dye can be firmly aligned in the alignment direction of the polymeric liquid crystal.

The thickness of the polarizing film at this time is usually 0.1 to 5 μm, preferably 0.3 to 3 μm, and more preferably 0.5 to 2 μm.

When laminating a polarizing film containing a polymerizable liquid crystal compound and a dichroic dye and a base film, not only the method of directly providing the polarizing film on the base film and laminating it is preferable, but also the method described above on another release film is preferable. A method of setting a polarizing film and transferring it to a base film. As a release film, a release support base material used in a laminated polarizing plate laminated with the release support base material mentioned above can be mentioned as a preferable example, and a polyester film, a polypropylene film can be mentioned. etc. as a particularly preferred release film. The release film can be subjected to corona treatment, release coating, easy-adhesion coating, etc. to adjust the peeling force.

The method of transferring the polarizing film to the base film is also the same as the method in the case where the polarizing plate is laminated on the releasable support base material and is laminated on the releasable support base material.

(orientation layer)

As mentioned above, the polarizing plate used in the present invention may not only be a polarizing film, but may also be a combination of a polarizing film and an alignment layer.

The orientation layer is used to control the orientation direction of the polarizing film. By providing the orientation layer, a polarizing plate with a higher degree of polarization can be provided.

As the alignment layer, any alignment layer may be used as long as the polarizing film can be brought into a desired alignment state. Examples of methods for providing an alignment state to the alignment layer include brushing of the surface, oblique evaporation of an inorganic compound, formation of a layer with micro-grooves, and the like. Furthermore, a method of forming a photo-alignment layer that produces an alignment function by irradiating polarized light is also preferred.

Hereinafter, two examples of the brushing treatment of the alignment layer and the photo-alignment layer will be described.

Brushing treatment of orientation layer

As the polymer material used in the alignment layer formed by brushing treatment, polyvinyl alcohol and its derivatives, polyimide and its derivatives, acrylic resin, polysiloxane derivatives, etc. are preferably used.

First, a coating liquid for a brushed alignment layer containing the above polymer material is applied onto a substrate film, and then heated and dried to obtain an alignment layer before brushing. The coating liquid for the alignment layer may contain a crosslinking agent. Examples of crosslinking agents include compounds containing multiple isocyanate groups, epoxy groups, oxazoline groups, vinyl groups, acryloyl groups, carbodiimide groups, alkoxysilyl groups, and the like; amides such as melamine compounds; Resin; phenolic resin, etc.

As the solvent of the coating liquid for the brushing treatment alignment layer, any solvent can be used without limitation as long as it dissolves the polymer material. Specific examples of the solvent include water; alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, ethylene glycol, propylene glycol, and cellosolve; and ester-based solvents such as ethyl acetate, butyl acetate, and γ-butyrolactone. ; Ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone; aromatic hydrocarbon solvents such as toluene and xylene; ether solvents such as tetrahydrofuran and dimethoxyethane, etc. These solvents can be used alone or in combination.

The concentration of the coating liquid for the brushing treatment alignment layer can be appropriately adjusted depending on the type of polymer, the thickness of the alignment layer to be produced, etc., and is preferably 0.2 to 20 mass%, more preferably 0.3 to 0.3% in terms of solid content concentration. 10 mass% range.

As a coating method, known methods such as coating methods such as gravure coating, die coating, rod coating, and applicator methods; and printing methods such as flexographic printing methods can be used.

The temperature of heat drying also depends on the base film. In the case of PET, the range of 30 to 170°C is preferred, the range of 50 to 150°C is more preferred, and the range of 70 to 130°C is still more preferred. If the drying temperature is too low, a longer drying time may be required, which may result in poor productivity. If the drying temperature is too high, it will affect the orientation state of the base film, reduce the retardation, or increase the thermal shrinkage of the base film. Therefore, the designed optical functions cannot be achieved, and problems such as poor planarity may occur. The heat drying time is usually 0.5 to 30 minutes, preferably 1 to 20 minutes, more preferably 2 to 10 minutes.

The thickness of the orientation layer subjected to brushing treatment is preferably 0.01 to 10 μm, more preferably 0.05 to 5 μm, and even more preferably 0.1 to 1 μm.

Brushing treatment can usually be performed by rubbing the surface of the polymer layer with paper or cloth in a constant direction. Usually, the surface of the orientation film is brushed using a brushing roller made of a fleece cloth made of fibers such as nylon, polyester, acrylic, etc.

In order to provide a polarizing film having a light transmission axis in a predetermined direction with respect to the length direction of the long base film, the brushing direction of the alignment layer also needs to form an angle consistent with this. The adjustment of the angle can be performed by adjusting the angle between the brushing roller and the base film, adjusting the conveying speed of the base film, the rotation speed of the roller, etc.

It should be noted that the base film can also be directly brushed so that the surface of the base film functions as an alignment layer. The above-mentioned cases are also included in the scope of protection of the present invention.

Photo alignment layer

The photo-alignment layer refers to an alignment film in which a coating liquid containing a polymer or monomer having a photoreactive group and a solvent is applied to a base film, and polarized light, preferably polarized ultraviolet light, is irradiated to impart an alignment regulating force. . The photoreactive group refers to a group that generates liquid crystal alignment ability by light irradiation. Specifically, it is a photoreaction that is the origin of liquid crystal alignment ability, such as orientation induction of molecules caused by irradiation of light or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photodecomposition reaction. Among the photoreactive groups, those that cause a dimerization reaction or a photocrosslinking reaction are preferable in terms of maintaining the smectic liquid crystal state of the polarizing film with excellent orientation. As the above photoreactive group capable of generating a reaction, an unsaturated bond is preferred, a double bond is particularly preferred, and a group selected from the group consisting of C=C bond, C=N bond, N=N bond and C=O bond is particularly preferred. at least one of the groups.

Examples of the photoreactive group having a C=C bond include a vinyl group, a polyalkenyl group, a stilbene group, a stilbazolyl group, a stilbazolium group, a chalcone group, a cinnamoyl group, and the like. Examples of the photoreactive group having a C=N bond include groups having structures such as aromatic SchiFF bases and aromatic hydrazones. Examples of the photoreactive group having an N=N bond include an azophenyl group, an azonaphthyl group, an aromatic heterocyclic azo group, a disazo group, a formazan group, and an oxyazo group. Benzene (azoxybenzene), etc. are the basic structures. Examples of the photoreactive group having a C=O bond include a benzophenone group, a coumarin group, an anthraquinone group, a maleimide group, and the like. These groups may have substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonate, and haloalkyl groups.

Among them, photoreactive groups that can cause a photodimerization reaction are preferable, and cinnamoyl groups and chalcone groups can easily obtain photoalignment with a small amount of polarized light irradiation required for photoalignment and excellent thermal stability or time-lapse stability. layer, so it is preferred. Furthermore, as a polymer having a photoreactive group, a polymer having a cinnamoyl group such that the terminal portion of the polymer side chain has a cinnamic acid structure is particularly preferred. Examples of the main chain structure include polyimide, polyamide, (meth)acrylic, polyester, and the like.

Specific examples of the alignment layer include Japanese Patent Application Laid-Open No. 2006-285197, Japanese Patent Application Laid-Open No. 2007-76839, Japanese Patent Application Laid-Open No. 2007-138138, Japanese Patent Application Laid-Open No. 2007-94071, and Japanese Patent Application Laid-Open No. 2007-94071. Japanese Patent Application Publication No. 2007-121721, Japanese Patent Application Publication No. 2007-140465, Japanese Patent Application Publication No. 2007-156439, Japanese Patent Application Publication No. 2007-133184, Japanese Patent Application Publication No. 2009-109831, Japanese Patent Application Publication No. 2002-229039 , Japanese Patent Application Publication No. 2002-265541, Japanese Patent Application Publication No. 2002-317013, Japanese Patent Application Publication No. 2003-520878, Japanese Patent Application Publication No. 2004-529220, Japanese Patent Application Publication No. 2013-33248, Japanese Patent Application Publication No. 2015 -The alignment layer described in Publication No. 7702, Japanese Patent Application Laid-Open No. 2015-129210, etc.

The solvent of the coating liquid for forming the photo-alignment layer can be used without limitation as long as it can dissolve the polymer and monomer having a photoreactive group. Specific examples of the solvent include those listed for brushing the alignment layer. If necessary, a photopolymerization initiator, a polymerization inhibitor, various stabilizers, etc. may be added to the coating liquid for forming a photo-alignment layer. In addition, a polymer having a photoreactive group and a polymer other than the monomer, and a polymer that does not have a photoreactive group that can be copolymerized with the monomer having a photoreactive group may be added to the coating liquid for forming the photo-alignment layer. Group monomers, etc.

The concentration of the coating liquid for forming the photo-alignment layer, the coating method, the drying conditions, etc. can be exemplified by brushing the alignment layer. The thickness of the photo-alignment layer is also the same as the preferred thickness of the brush-processed alignment layer.

By irradiating the pre-oriented photo-alignment layer thus obtained with polarized light in a predetermined direction with respect to the longitudinal direction of the base film, it is possible to obtain an orientation regulating force in a predetermined direction with respect to the longitudinal direction of the elongated base film. Photo-alignment layer.

The polarized light can be directly irradiated on the photo-alignment layer before alignment, or can be irradiated through the base film.

The wavelength of the polarized light is preferably in a wavelength range in which the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, ultraviolet rays with a wavelength in the range of 250 to 400 nm are preferred.

Examples of polarized light sources include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF. Preferred are high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps.

Polarized light can be obtained, for example, by passing light from the aforementioned light source through a polarizing plate. By adjusting the polarization angle of the polarizer, the direction of polarized light can be adjusted. Examples of the polarizing plate include polarizing filters; polarizing prisms such as Glan-Thompson and Glan-Taylor; and wire grid polarizing plates. The polarized light is preferably substantially parallel light.

By adjusting the angle of the polarized light to be irradiated, the direction of the orientation restricting force of the photo-alignment layer can be adjusted arbitrarily.

The irradiation intensity varies depending on the type or amount of the polymerization initiator or resin (monomer). For example, it is preferably 10 to 10000 mJ/cm ² based on 365 nm, and more preferably 20 to 5000 mJ/cm ² .

(The angle between the transmission axis of the polarizer and the slow axis of the base film)

The angle between the transmission axis of the polarizing plate and the slow axis of the base film is not particularly limited. In order to prevent dizziness or coloration when observing images with polarized sunglasses, the range of 30 to 60 degrees is preferable, and the range of 35 to 55 degrees is more preferable. In order to reduce minute iridescence when viewed from a shallow oblique direction with the naked eye, it is preferable to set it to 10 degrees or less, further to 7 degrees or less, or to 80 to 100 degrees, or further to 83 to 97 degrees. These angles can be adjusted by the angle at which the base film and the polarizing plate are bonded, the stretching direction of the base film by oblique stretching, or the orientation control angle of the alignment layer.

3. Phase difference layer

In the circularly polarizing plate used in the present invention, a retardation layer is present on the opposite side of the polarizing plate to the base film surface. That is, this circularly polarizing plate has a retardation layer on the electroluminescence (EL) element side of the polarizing plate. A state in which there is no self-standing film or only one self-standing film between the polarizer and the retardation layer (the retardation layer itself is also included between the polarizer and the retardation layer) is the EL display of the present invention. One of the features of the device. Here, the self-standing film refers to a form that exists independently in the form of a film in terms of the process.

In addition, the "retardation layer" here refers to a layer having a function as a circularly polarizing plate, and specifically refers to a 1/4 wavelength layer, a 1/2 wavelength layer, a C plate layer, etc.

The absence of a self-supporting film between the polarizing plate and the retardation layer means that the retardation layer is directly laminated on the polarizing plate instead of the self-supporting film. Here, "directly" means that there is no layer present between the polarizing plate and the retardation layer and between the retardation layers, or even if it exists, it is only an adhesive layer or a bonding layer.

The case where one self-supporting film exists between the polarizing plate and the retardation layer means that only one of the polarizing plate protective film and all the retardation layers is a self-supporting film.

The phase difference layer has a 1/2 wavelength layer and a 1/4 wavelength layer.

The 1/2 wavelength layer can be made by pasting a separately prepared 1/2 wavelength layer with a coating type described below on an oriented film (self-standing film) such as polycarbonate or cycloolefin or a triacetyl cellulose (TAC) film. A retardation film (self-supporting film) with two wavelength layers is obtained. However, from the viewpoint of thinning or ensuring flexibility, it is preferable to provide a coating-type 1/2-wavelength layer directly on the polarizing plate.

The coating-type 1/2-wavelength layer refers to a 1/2-wavelength layer in which the 1/2-wavelength layer itself is formed by coating and does not become an independent state. Examples of methods for providing a 1/2-wavelength layer include coating a polarizing plate with a retardation compound; and separately providing a 1/2-wavelength layer on a releasable base material and converting it to Methods of printing onto polarizing plates, etc. As the 1/2 wavelength layer, a layer formed of a liquid crystal compound is preferred. Examples of the liquid crystal compound include rod-shaped liquid crystal compounds, polymeric liquid crystal compounds, liquid crystal compounds having reactive functional groups, and the like. As a method of coating the polarizing plate with a retardation compound, it is preferable to brush the polarizing plate, or to provide the above-mentioned orientation layer on the polarizing plate to have an orientation control force and then apply the liquid crystal compound.

In the method of separately providing a coating type 1/2 wavelength layer on a releasable base material and transferring it to a polarizing plate, it is preferable to brush the releasable base material, or to apply the releasable base material to the polarizing plate. The above-mentioned alignment layer is provided on the material to have alignment control force, and then a liquid crystal compound (1/2 wavelength layer) is applied.

As a transfer method, a method of coating a releasable base material with a birefringent resin and stretching the base material together to form a 1/2 wavelength layer is also preferred.

The transfer-type 1/2-wavelength layer thus obtained is adhered to a polarizing plate using an adhesive or adhesive, and then the releasable base material is peeled off. In order to reduce the thickness, it is preferable to use an adhesive, especially an ultraviolet curable adhesive. It is also preferable to use an adhesive in terms of a process that does not require special equipment.

Since the polarizing plate is less susceptible to the influence of the coating solvent of the 1/2 wavelength layer, the following method is preferred: separately providing a coating type 1/2 wavelength layer on a release base material and transferring it to the polarizing plate. .

The front retardation of the 1/2 wavelength layer is preferably 200 to 360 nm, more preferably 240 to 300 nm.

For these methods and retardation layers, for example, Japanese Patent Application Laid-Open No. 2008-149577, Japanese Patent Application Laid-Open No. 2002-303722, WO2006/100830, Japanese Patent Application Laid-Open No. 2015-64418, etc. can be referred to.

Preferred raw materials, forms, manufacturing methods, lamination methods, etc. of the 1/4 wavelength layer are the same as those of the above 1/2 wavelength layer. Preferably, the 1/4 wavelength layer is provided on the 1/2 wavelength layer by coating, or the 1/4 wavelength layer is provided on the 1/2 wavelength layer by transfer.

The front retardation of the 1/4 wavelength layer is preferably 100 to 180 nm, more preferably 120 to 150 nm.

The angle (θ) between the orientation axis (slow axis) of the 1/2 wavelength layer and the transmission axis of the polarizing plate is preferably 5 to 20 degrees, and more preferably 7 to 17 degrees. The angle between the orientation axis (slow axis) of the 1/2 wavelength layer and the orientation axis (slow axis) of the 1/4 wavelength layer is preferably in the range of 2θ + 45 degrees ± 10 degrees, and more preferably 2θ + 45 degrees ± 5 degrees. The range is more preferably 2θ+45 degrees ±3 degrees.

When an oriented film is pasted, these angles can be adjusted based on the pasting angle, the stretching direction of the oriented film, etc.

In the case of coating-type 1/4 wavelength layer and 1/2 wavelength layer, the brushing angle, the irradiation angle of polarized ultraviolet rays, etc. can be controlled.

In the method of providing a coating-type 1/4-wavelength layer on a base material and transferring it to a polarizing plate, when applying it by roller-to-roller, it is preferable to use the brushing angle or the irradiation angle of polarized ultraviolet rays in advance. Control it to a prescribed angle.

In addition, when an oriented film is used or when a birefringent resin is coated on a base film and stretched together with the base material, it is preferable to stretch in an oblique direction so that it becomes prescribed when pasting with roller to roller. angle.

Furthermore, in order to reduce changes in coloration when viewed from an angle, it is also preferable to provide a C plate layer on the 1/4 wavelength layer. Among the C-plate layers, positive or negative C-plate layers can be used depending on the characteristics of the 1/4-wavelength layer or the 1/2-wavelength layer. The C plate layer is preferably a liquid crystal compound layer. The C plate layer can be directly applied to the 1/4 wavelength layer with a coating liquid that becomes the C plate layer, or a separately prepared C plate layer can be transferred.

As these lamination methods, various methods can be adopted. For example, the following method can be mentioned.

·A method of forming a 1/2-wavelength layer on a polarizing plate by transfer, and further forming a 1/4-wavelength layer on the polarizing plate by transfer.

·A method of sequentially placing a 1/4 wavelength layer and a 1/2 wavelength layer on a release film and transferring them to a polarizing plate.

·A method of forming a 1/2 wavelength layer on a polarizing plate by coating and forming a 1/4 wavelength layer by transfer.

·A method of preparing a film-like 1/2-wavelength layer, depositing a 1/4-wavelength layer on it by coating or transfer, and attaching it to a polarizing plate.

In addition, when stacking C plate layers, various methods can be used. For example, the following methods can be cited: a method of providing a C plate layer by coating or transfer on a 1/4 wavelength layer provided on a polarizing plate; and a method of pre-stacking a C plate layer on the 1/4 wavelength layer to be transferred or pasted. methods etc.

In the present invention, when there is a C plate layer between the polarizing plate and the 1/4 wavelength layer (including the 1/4 wavelength layer), it is preferable that all the layers from the polarizing plate to the C plate layer (including the C plate layer) are coating layer. This means that there is no self-standing film on the side of the polarizing plate opposite to the base film. Specifically, it means any one in which only an adhesive layer, a pressure-sensitive adhesive layer, a protective coating layer, an orientation layer, and a coating-type retardation layer are present on the opposite side of the polarizing plate from the base film. combination. By forming such a structure, it is possible to reduce the thickness of the circularly polarizing plate or to ensure flexibility.

Specific preferred examples of lamination between the polarizing plate and the quarter-wavelength layer include:

Polarizing plate/1/2 wavelength layer/adhesive layer/1/4 wavelength layer,

Polarizing plate/adhesive layer/1/2 wavelength layer/adhesive layer/1/4 wavelength layer,

Polarizing plate/protective coating layer/1/2 wavelength layer/adhesive layer/1/4 wavelength layer,

Polarizing plate/protective coating layer/adhesive layer/1/2 wavelength layer/adhesive layer/1/4 wavelength layer, etc.

It should be noted that the above-mentioned middle adhesive layer may be an adhesive layer. In addition, the 1/4 wavelength layer and the 1/2 wavelength layer may include an alignment layer on either side thereof.

As the adhesive layer, adhesives such as rubber-based, acrylic-based, urethane-based, olefin-based, silicone-based, etc. can be used without limitation. Among these, acrylic adhesives are preferred. The adhesive can be applied to an object, for example, the polarizing plate surface of a polarizing plate. A preferred method is to form an adhesive layer by peeling off the release film on one side of a substrate-free optically transparent adhesive (release film/adhesive layer/release film) and attaching it to the polarizing plate surface. . As the adhesive, it is preferable to use ultraviolet curing type, urethane type and epoxy type.

The adhesive layer or pressure-sensitive adhesive layer is used for bonding a polarizing plate, a protective coating layer, a coating-type retardation layer, or an image display element.

In addition, in the above, the retardation layer (1/4 wavelength layer and 1/2 wavelength layer) may be provided in a laminate of a base film and a polarizing plate and then attached to the object. However, it may be formed in advance. A retardation layer (a quarter-wavelength layer and a half-wavelength layer) is provided on the object in advance, and a laminate of a base film and a polarizing plate is bonded thereto. The same goes for setting up the C plate layer.

The thickness of the circularly polarizing plate obtained in this way is preferably 130 μm or less, more preferably 100 μm or less, further preferably 90 μm or less, particularly preferably 85 μm or less.

Furthermore, a circularly polarized light reflection layer made of a liquid crystal compound may be provided on the retardation layer of the circularly polarizing plate (the surface opposite to the polarizing plate). The circularly polarized light reflecting layer is preferably a cholesteric liquid crystal layer. The cholesteric liquid crystal layer may be one layer, but the cholesteric liquid crystal layer has wavelength selectivity in reflection characteristics. Therefore, in order to form uniform reflection characteristics in a wide range of visible light, it is preferable to provide a plurality of cholesteric liquid crystal layers. The cholesteric liquid crystal layer is more preferably two or more layers, and further preferably three or more layers. The number of cholesteric liquid crystal layers is preferably 7 or less layers, more preferably 6 or less layers, and particularly preferably 5 or less layers.

The circularly polarized light reflective layer is preferably provided by coating or transferring a circularly polarized light reflective layer containing a liquid crystal compound with a paint.

Examples of the liquid crystal compound used in the circularly polarized light reflecting layer include the liquid crystal compound used in the aforementioned polarizing film or retardation layer.

Furthermore, in order to orient the circularly polarized light reflective layer to cholesteric liquid crystal, it is preferable that the coating material for the circularly polarized light reflective layer contains a chiral agent. By containing a chiral agent, the helical structure of the cholesteric liquid crystal phase is induced, making it easier to obtain the cholesteric liquid crystal phase.

The chiral agent is not particularly limited, and known chiral agents can be used. Examples of chiral agents include Liquid Crystal Equipment Handbook, Chapter 3, Section 4-3, TN (Twisted Nematic), STN (Super-twisted nematic display) chiral agents, page 199, Japan Society for the Promotion of Science, Committee 142 Compounds described in 1989, isosorbide, isomannitol derivatives, etc. The chiral agent preferably has a polymerizable group. The compounding amount of the chiral agent is preferably 1 to 10 parts by mass relative to 100 parts by mass of the liquid crystal compound.

When the circularly polarized light reflective layer is provided on the retardation layer by coating, it may be directly coated on the retardation layer, or an orientation layer may be provided and coated thereon. When the circularly polarized light reflective layer is provided by transfer, it may be directly coated on a releasable base material, or an orientation layer may be provided on a releasable base material and a coating material for a circularly polarized light reflective layer may be applied thereon. You may also provide a circularly polarized light reflection layer and a phase difference layer in order on a releasable base material, and transfer it to a polarizing plate. Alternatively, a circularly polarized light reflection layer and a part of the retardation layer may be provided in this order on a releasable base material, and the other part of the retardation layer may be provided on a separate polarizing plate, and the retardation layer may be transferred to the retardation layer. As the alignment layer, the above-mentioned alignment layer is preferably used.

Examples of the circularly polarized light reflecting layer include Japanese Patent Application Publication No. 1-133003, Japanese Patent Application Publication No. 3416302, Japanese Patent Application Publication No. 3363565, Japanese Patent Application Publication No. 8-271731, International Publication No. 2016/194497, and Japanese Patent Application Publication No. 2018. -10086, etc., please refer to these.

The thickness of the circularly polarized light reflecting layer is preferably 2.0 to 150 μm, more preferably 5.0 to 100 μm. In addition, even when there are multiple circularly polarized light reflecting layers, the total thickness is preferably within the above range.

By combining the circularly polarized light reflection layer with the circularly polarizing plate, it is possible to reduce the decrease in brightness when the antireflection circularly polarizing plate is provided in the EL display device. Further, the polarizing plate, the phase difference layer and the circularly polarized light reflecting layer are provided by coating or transferring, and by forming between the polarizing plate and the circularly polarized light reflecting layer (including the polarizing plate itself and the circularly polarized light reflecting layer) there is no self-standing The structure of the thin film makes it possible to reduce the thickness of the circular polarizing plate, making it easier to cope with the thinning of EL display devices. In addition, such a structure is optimal as a flexible EL display device that can be folded, rolled, or the like.

B.EL element

The EL display device of the present invention includes the above-mentioned circular polarizing plate on the viewing side closer to the EL element. Known EL elements can be used without limitation. Among them, organic EL elements are preferred because they are thin. The EL element and the circular polarizing plate are preferably bonded with an adhesive.

The EL display device of the present invention uses a base film with a specific in-plane retardation, sets the number of self-standing films between the polarizer and the retardation layer to one or less, uses a 1/2 wavelength layer and 1 The /4 wavelength layer circular polarizing plate serves as a phase difference plate, so it has excellent visibility (suppresses rainbow spots), can be thinned, and is less likely to cause trouble in the manufacturing process. It is particularly suitable for use in large EL display devices of type 40 or above (the diagonal length of the display part is 40 inches) and type 50 or above (the diagonal length of the display part is 50 inches).

In addition, when a flexible EL display device is formed, the laminated members are not easily peeled off from each other and creases are not easily formed when the EL display device is repeatedly bent or left in a high-temperature state.

As a flexible EL display device, it is preferable to use an EL display device that can be folded into a V-shape, a Z-shape, a W-shape, a double door shape, etc. when being carried (folding type EL display device), or that can be rolled up into a roll. Any of the EL display devices (roll-type EL display devices).

When the foldable EL display device has a display unit on the folded inner surface side, the bending radius of the circular polarizing plate in the folded state becomes small. In the case of such an EL display device, the occurrence of creases caused by repeated folding operations can be effectively reduced by arranging the main orientation direction of the base film perpendicular to the folding direction (the direction of the folding operation). It should be noted that in the vertical direction, the angle between the main orientation direction of the base film and the folding direction is preferably 75 to 105 degrees, more preferably 80 to 100 degrees, and even more preferably 83 to 97 degrees.

The reason why the occurrence of creases can be reduced is considered to be because the base film is stretched by repeated folding operations, or the direction of stretching is perpendicular to the main orientation direction of molecules, so the base film becomes easier to elongation. The flexible image display device of the present invention can be suitably used in a foldable image display device having a bending radius of 5 mm or less, further 4 mm or less, and particularly 3 mm.

When the foldable EL display device has a display unit on the folded outer surface of the device, when the bending radius is not small even when it is on the inner surface, or when it is a roll-type image display device, it may be used without any particular restrictions. Use the main orientation direction of the base film. However, in such a case, it is also preferable to make the main orientation direction of the base film parallel to the folding direction. By forming parallel elements, the flatness of the entire image display device when expanded tends to become better. In the above case, the angle between the main orientation direction of the base film and the folding direction is preferably 15 degrees or less, more preferably 10 degrees or less, and still more preferably 7 degrees or less.

The flexible EL display device of the present invention will not be peeled off even if it is repeatedly bent or left in a high temperature state, is less likely to be creased, and has excellent visibility. When a polyester film is further used as the base film of the circularly polarizing plate, an EL display device having a circularly polarizing plate excellent in moisture permeability resistance, dimensional stability, mechanical strength, and chemical stability can be provided.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. It can also be implemented with appropriate modifications within the scope that conforms to the gist of the present invention, and these are all included in the protective scope of the present invention.

The evaluation method of physical properties in the Examples is as follows.

(1) Delay amount (Re)

The retardation is a parameter defined by the product (ΔNxy×d) of the orthogonal biaxial refractive index anisotropy (ΔNxy=|nx-ny|) on the film and the film thickness d (nm), It is a scale expressing optical isotropy and anisotropy. The biaxial refractive index anisotropy (ΔNxy) was determined by the following method. Using a molecular orientation meter (MOA-6004 molecular orientation meter manufactured by Oji Scientific Instruments Co Ltd.), the orientation axis direction of the film was determined, and the film was cut into a 4 cm × 2 cm rectangle so that the orientation axis direction became the long side, and was used as a measurement sample. For this sample, the refractive index (nx, ny) of the orthogonal biaxial axis and the refractive index (nz) of the thickness direction were measured using an Abbe refractometer (NAR-4T, manufactured by ATAGOCO., LTD., measurement wavelength 589 nm). , the absolute value of the difference in the biaxial refractive index (|nx-ny|) is defined as the refractive index anisotropy (ΔNxy). The thickness d (nm) of the film was measured with an electronic micrometer (Millitron 1245D manufactured by Fine Ryuf Co., Ltd.), and the unit was converted into nm. The retardation (Re) is calculated from the product (ΔNxy×d) of the refractive index anisotropy (ΔNxy) and the thickness d (nm) of the film.

(2)Nz coefficient

Use the value obtained from |ny-nz|/|ny-nx| as the Nz coefficient. Among them, the values of ny and nx are selected so that ny>nx.

(3) Degree of plane orientation (ΔP)

Let the value obtained by (nx+ny)/2-nz be the plane orientation degree (ΔP).

(4) Thickness direction retardation (Rth)

The thickness direction retardation is the retardation obtained by multiplying the two birefringences ΔNxz (=|nx-nz|) and ΔNyz (=|ny-nz|) by the film thickness d when viewed cross-sectionally in the film thickness direction. average parameters. Using the same method as the measurement of retardation, determine nx, ny, nz and film thickness d (nm), calculate the average value of (△Nxz×d) and (△Nyz×d), and calculate the thickness direction retardation ( Rth).

(5)Light transmittance at wavelength 380nm

Using a spectrometer (U-3500 model manufactured by Hitachi, Ltd.), the light transmittance of each film in the wavelength range of 300 to 500 nm was measured using the air layer as a standard, and the light transmittance at a wavelength of 380 nm was determined.

Each characteristic of the above-mentioned base film was sampled at three points in the width direction (three points at the center and both ends), and the average value was obtained.

(6) The angle between the main axis of film orientation and the length direction or a direction orthogonal to the length direction

The orientation main axis direction of the film was determined using a molecular orientation meter (MOA-6004 molecular orientation meter manufactured by Oji Scientific Instruments Co., Ltd.) and expressed as an angle with the longitudinal direction or a direction orthogonal to the longitudinal direction.

(7) Thickness of base film and circular polarizing plate

Use a commercially available digital thickness meter to measure the thickness of the base film and circular polarizing plate.

(8) Based on the thickness of each layer applied

The thickness of each coating layer is as follows: under the same coating conditions, a PET film (PET that has been subjected to an easy-adhesion treatment if necessary) is coated with epoxy resin and cut into slices. , observe with a microscope. Microscopes include optical microscopes, transmission electron microscopes, and scanning electron microscopes depending on the thickness.

(9) Operability

The produced circular polarizing plate was cut into an A5 equivalent, and a paper tube with an outer diameter of 6 inches was rolled up together with a biaxially stretched PET film with a thickness of 50 μm so that the length direction became the winding direction. The winding was performed as follows: when the PET film had been wound for 3 m, the circular polarizing plate sample was inserted, and the PET film was further wound for 7 m. In addition, as a blank, one in which only the base film was wound was prepared. These were stored at 40° C. for 3 days, returned to room temperature, and then uncoiled with the curled convex portion upward, placed on a glass plate, and observed the curled state after 30 minutes. Also, press it from above to see if it flattens easily. The evaluation criteria are as follows.

◎: Basically the same as blank, and basically no curl.

○: Compared with the blank, the curl is slightly stronger, but it is easy to flatten.

△: Compared with the blank, the curl is stronger, but it can be flattened.

×: The curl is quite strong compared to the blank and is difficult to flatten.

(10)Polarized sunglasses response

Instead of removing the circular polarizing plate (arranged on the organic EL display) from a commercially available organic EL display (organic EL TV C6P 55 inches manufactured by LG Corporation), the circular polarizing plate obtained below was placed in an organic EL display so that the PET film was placed on the visible side. The EL element is also close to the circular polarizing plate on the viewing side). The absorption axis of the polarizing plate is arranged so that it is the same as the absorption axis of the polarizing plate of the original circularly polarizing plate.

Wear polarized sunglasses to view the monitor. The evaluation criteria are as follows.

○: No iridescent spots are observed, and the image is visible (the slow axis direction of the base film and the absorption axis direction of the polarizer are approximately 45 degrees)

×: An angle at which the image becomes blurred and becomes invisible (the slow axis direction of the base film is orthogonal or parallel to the absorption axis direction of the polarizing plate)

(11)Anti-reflective effect

The anti-reflection effect of the EL display device used in the evaluation of (10) above was visually confirmed.

○: It was confirmed that the anti-reflection effect is basically the same as that of the original circular polarizing plate.

×: No anti-reflection effect is confirmed.

(12)r=3 bending resistance

A circular polarizing plate sample with a size of 50 mm×100 mm was prepared, and the bending radius was set to 3 mm using a non-loaded U-shaped telescopic testing machine (DLDMLH-FS manufactured by Yuasa System Co., Ltd.), and the sample was bent 100,000 times at a speed of 1 time/second. At this time, for the sample, the positions of 10 mm from both ends of the long side were fixed, and the bent part was set to 50 mm × 80 mm. The inside of the bend was the base film side, and the slow axis of the base film was orthogonal to the bending direction. . After the bending process is completed, place the sample on a flat surface with the bent inner side facing down, and conduct a visual inspection. The evaluation criteria are as follows.

◎: Deformation of the sample cannot be confirmed.

○: There is deformation of the sample, but when placed horizontally, the maximum floating height is less than 5 mm.

×: There are creases in the sample, or when placed horizontally, the maximum floating height is more than 5 mm.

(13)r=5 bending resistance

The bending radius was set to 5 mm, the outside of the bend became the base film side, and the slow axis of the base film was parallel to the bending direction. The same procedure as the r=3 bending resistance test was performed.

(14)Heat bending resistance

With the base film surface on the inside, bend a 50mm×100mm sample at 180 degrees along the long side so that the bending radius becomes 3mm, fix it with a jig, and leave it for 3 hours at a temperature of 60°C and RH65%. Then remove the fixture at room temperature and observe the state after 1 hour. Make the slow axis of the base film orthogonal to the bending direction. The evaluation criteria are as follows.

◎: Basically restored to flat surface

○: In a slightly curved state (less than 20 degrees)

×: In a bent state (more than 20 degrees)

<Manufacture of easy-adhesion layer components>

(Polymerization of polyester resin)

Into a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial reflux condenser, 194.2 parts by mass of dimethyl terephthalate, 184.5 parts by mass of dimethyl isophthalate, and 5-5 parts by mass of dimethyl isophthalate were placed. 14.8 parts by mass of sodium sulfonate, 233.5 parts by mass of diethylene glycol, 136.6 parts by mass of ethylene glycol, and 0.2 parts by mass of tetra-n-butyl titanate were subjected to a transesterification reaction at a temperature of 160°C to 220°C for 4 hours. Next, the temperature of the mixture was raised to 255°C, and the pressure of the reaction system was gradually reduced, and then the reaction was carried out under a reduced pressure of 30 Pa for 1 hour and 30 minutes to obtain a copolymerized polyester resin. The obtained copolymerized polyester resin was light yellow and transparent. The reduced viscosity of the copolymerized polyester resin was measured and found to be 0.70 dl/g. In addition, the reduced viscosity is a value obtained by using 25 mL of a mixed solvent of phenol (60 mass %) and 1,1,2,2-tetrachloroethane (40 mass %) for 0.1 g of resin as the solvent. , value measured at 30°C. The glass transition temperature based on DSC is 40°C.

(Preparation of polyester aqueous dispersion)

In a reactor equipped with a stirrer, a thermometer, and a reflux device, 30 parts by mass of polyester resin and 15 parts by mass of ethylene glycol n-butyl ether were placed, and the resin was stirred while heating at 110° C. to dissolve the resin. After the resin was completely dissolved, the polyester solution was stirred, and 55 parts by mass of water was slowly added. After the addition, the mixture was stirred and cooled to room temperature to obtain a milky white polyester aqueous dispersion with a solid content of 30% by mass.

(Preparation of polyvinyl alcohol aqueous solution)

90 parts by mass of water was put into a container equipped with a stirrer and a thermometer, and 10 parts by mass of polyvinyl alcohol resin (manufactured by Kuraray, degree of polymerization 500, degree of saponification 74%) was slowly added while stirring. After the addition is completed, the mixture is heated to 95°C while stirring to dissolve the resin. After the resin was dissolved, the mixed solution was cooled to room temperature while stirring, to obtain a polyvinyl alcohol aqueous solution with a solid content of 10% by mass.

(Polymerization of the blocked polyisocyanate cross-linking agent used in the easy-adhesion layer P1)

Into a flask equipped with a stirrer, a thermometer, and a reflux condenser, 100 parts by mass of a polyisocyanate compound having an isocyanurate structure (manufactured by Asahi Kasei Chemicals Corporation, Duranate TPA) using hexamethylene diisocyanate as a raw material, and propylene glycol were placed. 55 parts by mass of monomethyl ether acetate and 30 parts by mass of polyethylene glycol monomethyl ether (average molecular weight 750) were maintained at 70° C. for 4 hours in a nitrogen atmosphere. Thereafter, the temperature of the reaction solution was lowered to 50° C., and 47 parts by mass of methyl ethyl ketoxime was added dropwise. The infrared spectrum of the reaction liquid was measured, and it was confirmed that the absorption of the isocyanate group disappeared, and a blocked polyisocyanate aqueous dispersion with a solid content of 75% by mass was obtained.

(Preparation of coating liquid for easy-bonding layer P1)

Mix the following raw materials to prepare a coating liquid.

(Polymerization of urethane resin used in easy-adhesion layer P2)

A urethane resin containing an aliphatic polycarbonate polyol as a constituent component was produced according to the following procedure. In a four-necked flask equipped with a mixer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube and a thermometer, 43.75 parts by mass of 4,4-diphenylmethane diisocyanate, 12.85 parts by mass of dimethylol butyric acid, and a few 153.41 parts by mass of polyhexamethylene carbonate diol with an average molecular weight of 2000, 0.03 parts by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent were stirred at 75°C for 3 hours in a nitrogen atmosphere, and it was confirmed that The reaction solution reaches the specified amine equivalent. Next, after lowering the temperature of the reaction solution to 40° C., 8.77 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 g of water was added to a reaction vessel equipped with a homogeneous disperser capable of high-speed stirring, and the temperature was adjusted to 25°C. The polyurethane prepolymer solution was added and dispersed while stirring and mixing the water for 2000 min ^-1 . Thereafter, acetone and part of water were removed from the mixed liquid under reduced pressure to prepare a water-soluble polyurethane resin with a solid content of 35%. The glass transition point temperature of the obtained polyurethane resin containing aliphatic polycarbonate polyol as a constituent component was -30°C.

(Polymerization of the oxazoline cross-linking agent used in the easy-adhesion layer P2)

Into a flask equipped with a thermometer, a nitrogen introduction tube, a reflux condenser, a dropping funnel, and a stirrer, a mixture of 58 parts by mass of ion-exchange water and 58 parts by mass of isopropyl alcohol as an aqueous medium, and a polymerization initiator (2,2 '-Azobis(2-amidinopropane) dihydrochloride) 4 parts by mass. On the other hand, 16 parts by mass of 2-isopropenyl-2-oxazoline, which is a polymerizable unsaturated monomer having an oxazoline group, and methoxy polyethylene glycol acrylate ( The average number of moles of ethylene glycol added: 9 moles, a mixture of 32 parts by mass of Shin-Nakamura Chemical Co., Ltd. and 32 parts by mass of methyl methacrylate was added dropwise at 70° C. over 1 hour in a nitrogen atmosphere. After completion of the dropwise addition, the reaction solution was stirred for 9 hours and cooled to obtain a water-soluble resin having an oxazoline group with a solid content concentration of 40% by mass.

(Preparation of coating liquid for easy-adhesion layer P2)

The following raw materials are mixed to prepare a coating liquid for forming a coating layer with excellent adhesion to the functional layer.

<Manufacturing of polyester resin for base film>

(Manufacturing Example 1-Polyester X)

The esterification reactor was heated up, and when it reached 200°C, 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were added, and 0.017 parts by mass of antimony trioxide and 0.064 parts by mass of magnesium acetate tetrahydrate as catalysts were added while stirring. parts by mass, triethylamine 0.16 parts by mass. Next, the pressure was increased and the temperature was increased. After performing a pressurized esterification reaction under the conditions of 0.34 MPa gauge pressure and 240° C., the esterification reactor was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Furthermore, the temperature was raised to 260°C over 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added. Then, after 15 minutes, a high-pressure disperser was used to perform dispersion treatment. After 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reactor, and a polycondensation reaction was performed at 280° C. under reduced pressure.

After the polycondensation reaction is completed, the product is filtered through a Naslon filter with a 95% cutoff diameter of 5 μm, extruded from the nozzle in a strand shape, and cooled with cooling water that has been filtered in advance (pore size: 1 μm or less). and solidified, cut into pellets. The obtained polyethylene terephthalate resin (X) had an intrinsic viscosity (intrinsic viscosity) of 0.68 dL/g and contained substantially no inactive particles and internal precipitated particles (hereinafter, the polyethylene terephthalate resin will be Alcohol ester resin (X) is abbreviated as PET (X)).

(Manufacturing Example 2-Polyester Y)

10 parts by mass of dried ultraviolet absorber (2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one)) and 90 parts by mass of PET(X) Mix and use a kneading extruder to obtain a polyethylene terephthalate resin (Y) containing an ultraviolet absorber. (Hereinafter, the polyethylene terephthalate resin (Y) will be abbreviated as PET(Y).)

(Manufacture of base film)

As raw materials for the base film intermediate layer, 90 parts by mass of PET (X) resin pellets without particles and 10 parts by mass of PET (Y) resin pellets containing an ultraviolet absorber were dried under reduced pressure at 135°C (1 Torr) 6 Hours later, it is supplied to extruder 2 (for the middle layer II layer). In addition, the PET (X) is dried by a conventional method, and supplied to extruder 1 (for the outer layer I layer and outer layer III) respectively, at 285 °C for dissolution. The two types of polymers were filtered using stainless steel sintered filter media (nominal filtration accuracy: 10 μm particles, 95% cutoff), laminated in two types of three-layered flow blocks, formed into sheets from the tube head, and extruded using Using the electrostatic casting method, the film is wound up into a casting drum with a surface temperature of 30°C, cooled and solidified, and an unstretched film is produced. At this time, the discharge amount of each extruder was adjusted so that the thickness ratio of the I layer, the II layer, and the III layer became 10:80:10.

Next, P1 is applied to one side of the unstretched PET film and P2 coating liquid is applied to the opposite side by the reverse roll method so that the coating amount after drying becomes 0.12 g/m ² , and then introduced into a dryer. , dry at 80°C for 20 seconds.

The unstretched film on which the coating layer was formed was introduced into a tenter stretching machine, and while fixing the ends of the film with a clamp, it was introduced into a hot air zone with a temperature of 135° C., and stretched to 3.8 times in the width direction. Next, the film was processed at a temperature of 225° C. for 30 seconds while maintaining the stretched width in the width direction, and then both ends of the film cooled to 130° C. were cut with a shear blade, and the film was heated to 0.5 kg/mm ² The ears are cut off with a high tension and then rolled up to obtain a uniaxially oriented PET film (TD) with a film thickness of 70 μm. In addition, the intrinsic viscosity of the entire film is 0.65 dL/g. Table 1 shows the characteristics of the obtained uniaxially oriented PET film (TD).

The direction of the orientation main axis (slow axis) of the film was measured at a total of five points at both ends in the longitudinal direction of the film, the middle portion, and the middle portion located between the end portions and the center portion. The orientation main axis is a direction orthogonal to the length direction, and the angle between the orientation main axis and the direction orthogonal to the length direction is 0 degrees as an average of 5 points, and the maximum angle among the 5 points is 5 degrees.

The unstretched film obtained in the same manner was heated to 105°C using a heated roller set and an infrared heater, and then stretched 4 times in the traveling direction on a roller set with a circumferential speed difference. Next, using the reverse roll method, P1 was applied to one side of the longitudinally stretched PET film and P2 coating liquid was applied to the opposite side so that the coating amount after drying became 0.12 g/m ² , and then introduced Go to the tenter stretching machine, fix the end of the film with a clamp, dry it at a temperature of 135°C while maintaining the width, and then treat it at a temperature of 220°C for 30 seconds, then cool to 130°C and wind it up to obtain the film thickness. 70μm uniaxially oriented PET film (MD). Table 1 shows the characteristics of the obtained uniaxially oriented PET film (MD).

The main axis of orientation of the obtained film was the longitudinal direction, and the angle between the main axis of orientation and the longitudinal direction was 0 degrees as an average of 5 points, and the maximum angle among the 5 points was 1 degree.

[Table 1]

Base film Transmittance at 380nm Re Re/Rth Nz ΔP PET film(TD) 1% 7140 0.90 1.60 0.113 PET film(MD) 1% 7070 0.86 1.66 0.118

(Lamination of hard coat)

95 parts by mass of a urethane acrylate hard coating agent (manufactured by Arakawa Chemical Industry Co., Ltd., BEAMSET (registered trademark) 577, solid content concentration 100%), a photopolymerization initiator (manufactured by BASF Japan Co., Ltd., Irgacure (registered trademark) Trademark) 184, solid content concentration 100%) 5 parts by mass and leveling agent (BYK Japan Co., Ltd., BYK307, solid content concentration 100%) 0.1 part by mass were mixed, and diluted with a solvent of toluene/MEK=1/1 , prepare a coating liquid with a concentration of 40%.

Using a Meyer rod, apply the hard coat coating liquid on the easy-adhesion layer P2 surface of the base film so that the film thickness after drying becomes 5.0 μm. After drying at 80°C for 1 minute, irradiate ultraviolet rays (accumulated light intensity: 200 mJ/cm ² ).

(Lamination of polarizing plates)

As a method of providing a polarizing plate on a base film, the following four methods were performed.

(A) A method in which a brushed alignment layer is provided on a base film and a polarizing film composed of a liquid crystal compound and a dichroic dye is provided on the base film (Polarizer lamination method A)

(B) A method in which a photo-alignment layer is provided on a base film, and a polarizing film formed of a liquid crystal compound and a dichroic dye is provided thereon (Polarizer lamination method B)

(C) A method of placing a polarizing film made of PVA/iodine on a thermoplastic base material and then transferring it to a base film (polarizing plate lamination method C)

(D) Method of making a polarizing film composed of PVA/iodine and pasting it to a base film (polarizing plate lamination method D)

Details of each method are described below.

Polarizer stacking method A

(Formation of brushed alignment layer)

Use a bar coater to apply a paint for a brushed alignment layer with the following composition on the easy-adhesion layer P1 surface of the base film, and dry it at 120° C. for 3 minutes to form a film with a thickness of 200 nm. Next, the surface of the obtained film was treated with a brushing roller in which a nylon raised cloth was wound, to obtain a base film on which a brushed orientation layer was laminated. Make the brushing direction 0 degree, 45 degrees or 90 degrees relative to the length direction of the film.

Brushing paint for alignment layer

Completely saponified polyvinyl alcohol molecular weight 800 2 parts by mass

100 parts by mass of ion exchange water

(Synthesis of polymerizable liquid crystal compound)

Using the description of paragraph [0134] of Japanese Patent Publication No. 2007-510946 and Lub et al. Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996) as a reference, the following formula (1) was synthesized The compound (1) shown and the compound (2) represented by the following formula (2).

The pigment (3) represented by the following formula (3) was synthesized with reference to Example 1 of Japanese Patent Application Laid-Open No. Sho 63-301850.

Using Example 2 of Japanese Patent Publication No. 5-49710 as a reference, the pigment (4) represented by the following formula (4) was synthesized.

The pigment (5) represented by the following formula (5) was synthesized with reference to the method for producing the compound of general formula (1) in Japanese Patent Publication No. 63-1357.

(Formation of polarizing film)

Using a bar coater, a mixture containing 75 parts by mass of compound (1), 25 parts by mass of compound (2), 2.5 parts by mass of pigment (3), 2.5 parts by mass of pigment (4), 2.5 parts by mass of pigment (5), and Irgacure (registered 6 parts by mass of polarizing film coating material (trademark) 369E (manufactured by BASF Co., Ltd.) and 250 parts by mass of o-xylene were applied to the base film on which the brushed alignment layer was laminated, and dried at 110°C for 3 minutes to form a 2 μm thick membrane. Next, UV light is irradiated, and a polarizing plate is placed on the base film.

Polarizer stacking method B

(Synthesis of paint for photo-alignment layer)

Based on the description of Example 1, Example 2 and Example 3 of Japanese Patent Application Laid-Open No. 2013-33248, a 5 mass % solution of cyclopentanone of the polymer (6) represented by the following formula (6) was produced.

(Formation of photo alignment layer)

The coating material for the photo-alignment layer having the above composition was applied to one side of the base film using a bar coater, and dried at 80° C. for 1 minute to form a film with a thickness of 150 nm. Next, polarized UV light is irradiated to obtain a base film on which a photo-alignment layer is laminated. The polarization direction of UV light was set to 45 degrees with respect to the length direction of the film.

The aforementioned coating material for polarizing films is applied on the photo-alignment layer, and a polarizing layer is similarly provided on the base film on which the alignment layer is laminated.

Polarizer stacking method C

(Manufacture of base material laminated polarizing plate)

Polyester PVA layer.

The obtained laminate was stretched to twice the length in the length direction between rollers having different circumferential speeds at 120° C., and then wound up. Next, the obtained laminate was treated in a 4% boric acid aqueous solution for 30 seconds, then immersed in a mixed aqueous solution of iodine (0.2%) and potassium iodide (1%) for 60 seconds for dyeing, and then stained in a potassium iodide (3%) solution. ) and boric acid (3%) in a mixed aqueous solution for 30 seconds.

Furthermore, the laminate was uniaxially stretched in the longitudinal direction in a mixed aqueous solution of boric acid (4%) and potassium iodide (5%) at 72°C. The stretched laminate was then washed with a 4% potassium iodide aqueous solution. After removing the aqueous solution with an air knife, it was dried in an oven at 80°C, and both ends were cut and rolled up to obtain a 30cm wide and 1000m long laminate. The polarizing plate 1 is laminated on the base material. The total stretching ratio was 6.5 times, and the thickness of the polarizing plate was 5 μm. In addition, the thickness is as follows: the base material laminated polarizing plate 1 is embedded in epoxy resin, cut into slices, and observed and read with an optical microscope.

(Lamination of polarizing layers)

After the base film is coated with an ultraviolet curable acrylic adhesive, the polarizing plate surface of the base laminated polarizing plate 1 is adhered, ultraviolet rays are irradiated from the base laminated polarizing plate 1 side, and the base laminated film is laminated on the base film. Polarizer 1. Thereafter, the thermoplastic resin base material is peeled off, and a polarizing plate is provided on the base film.

Polarizer stacking method D

(Manufacture of single-layer polarizer)

A polyvinyl alcohol resin film with a saponification degree of 99.9% was introduced into a roller with a circumferential speed difference, and uniaxially stretched to 3 times at 100°C. The obtained stretched polyvinyl alcohol stretched film was dyed in a mixed aqueous solution of potassium iodide (0.3%) and iodine (0.05%), and then uniaxially stretched to 1.8 times in a 10% boric acid aqueous solution at 72°C. Thereafter, the film was washed with ion-exchanged water, further immersed in a 6% potassium iodide aqueous solution, and the aqueous solution was removed with an air knife, and then dried at 45° C. to obtain a polarizing plate. The thickness of the polarizing plate is 18 μm.

(Lamination of polarizing plates)

After the base film is coated with an ultraviolet curable acrylic adhesive, a single-layer polarizer is attached, ultraviolet rays are irradiated from the side of the base where the polarizer is laminated, and the polarizer is placed on the base film.

(Lamination of phase difference layers)

As a method of providing a retardation layer on a polarizing plate, the following four methods have been performed.

(F) Method of providing a 1/2 wavelength layer and a 1/4 wavelength layer on a polarizing plate by coating (laminated method of phase difference layer F)

(G) A method of transferring the 1/2-wavelength layer provided on the release film to a polarizing plate, and further transferring the 1/4-wavelength layer provided on the release film (laminated method G of phase difference layer) )

(H) A method of providing a 1/4 wavelength layer and a 1/2 wavelength layer on a release film and transferring them to a polarizing plate (retardation layer stacking method H)

(I) A method in which a 1/2 wavelength layer is provided by coating on the 1/4 wavelength layer, and these 1/2 wavelength layers are adhered to the polarizing plate (phase difference layer stacking method I)

Details of each method are described below.

Phase difference layer stacking method F

A 2 mass% aqueous solution of polyvinyl alcohol (polyvinyl alcohol 1000 completely saponified type (0.2% surfactant)) was applied to the polarizing plate provided on the base film and dried to obtain a polyvinyl alcohol film with a thickness of about 100 nm. Then, The surface of the polyvinyl alcohol film was brushed so that the angle of the brushing became 15 degrees with respect to the absorption axis of the polarizing plate.

Next, a retardation layer forming solution having the following composition was applied to the surface subjected to brushing treatment by a bar coating method. The coated film is dried, subjected to orientation treatment, and then cured by irradiation with ultraviolet rays to form a 1/2 wavelength layer.

Solution for retardation layer formation

LC242 (manufactured by BASF Co., Ltd.) 75 parts by mass

20 parts by mass of the following compound

5 parts by mass of trimethylolpropane triacrylate

Irgacure379 3 parts by mass

Surfactant 0.1 parts by mass

Methyl ethyl ketone 250 parts by mass

Next, a polyvinyl alcohol film was similarly provided on the 1/2 wavelength layer and brushed. The brushing process is performed so that the angle with respect to the absorption axis of the polarizing plate becomes 73 degrees. The solution for forming a retardation layer is applied by a bar coating method and dried. After alignment treatment, the solution is irradiated with ultraviolet rays and cured. During bar coating, adjust the thickness so that it becomes a 1/4 wavelength layer.

Phase difference layer stacking method G

A biaxially stretched polyethylene terephthalate (PET) film with a thickness of 50 μm was brushed. On the brushed surface, a solution for forming a retardation layer is applied by a bar coating method and dried. After orientation treatment, it is irradiated with ultraviolet rays to cure, and is placed on a biaxially stretched polyethylene terephthalate film. 1/2 wavelength layer. Next, an ultraviolet curable adhesive is used to bond the 1/2 wavelength layer to the polarizing plate surface provided on the base film. After that, the biaxially stretched PET film is peeled off. The adhesion is performed at an angle of 15 degrees relative to the absorption axis of the polarizing plate.

Similarly, a 1/4-wavelength layer was provided on the biaxially stretched PET film, and an optically transparent adhesive sheet was used to affix it to the 1/2-wavelength layer. The adhesion is performed at an angle of 75 degrees to the absorption axis of the polarizing plate.

Phase difference layer stacking method H

A biaxially stretched polyethylene terephthalate (PET) film with a thickness of 50 μm was brushed. On the brushed surface, a solution for forming a retardation layer is applied by a bar coating method and dried. After orientation treatment, it is irradiated with ultraviolet rays to cure, and is placed on a biaxially stretched polyethylene terephthalate film. 1/4 wavelength layer. Furthermore, polyvinyl alcohol (a 2 mass% aqueous solution of polyvinyl alcohol 1000 completely saponified type (0.2% surfactant)) was applied to the 1/4 wavelength layer and dried to obtain a polyvinyl alcohol film with a thickness of about 100 nm. Then, The surface of the polyvinyl alcohol film is brushed. On the brushed surface of the PVA, a retardation layer forming solution is applied by a bar coating method and dried. After orientation treatment, ultraviolet rays are irradiated to cure, and 1/2 Wavelength layer. Carry out so that the angle between the brushing direction when the 1/4 wavelength layer is provided and the brushing direction when the 1/2 wavelength layer is provided becomes 60 degrees. Furthermore, use an ultraviolet curable adhesive to make 1 The /2-wavelength layer is pasted on the polarizer surface provided on the base film. Afterwards, the biaxially stretched PET film is peeled off. During the pasting, the absorption axis of the polarizer and the brushing direction of the 1/2-wavelength layer are aligned at 15 degrees. The absorption axis of the sheet and the brushing direction of the 1/4 wavelength layer are 75 degrees.

Phase difference layer stacking method I

Unwind the 1/4-wavelength film from the roll of the 1/4-wavelength film having a slow axis in the length direction, cut it into the desired length, and brush the surface. A 1/2 wavelength layer is provided on the brushed surface using the same method as the stacking method F of the retardation layer. Furthermore, an ultraviolet curable adhesive is used to bond the 1/2 wavelength layer to the polarizing plate surface provided on the base film. It should be noted that the quarter-wavelength film was produced by extruding a propylene-ethylene random copolymer (ethylene content: 5%) into a sheet shape and stretching it with a roller in the longitudinal direction. Manufactured (thickness 20μm). During pasting, the absorption axis of the polarizer and the brushing direction of the 1/2 wavelength layer are 15 degrees, and the absorption axis of the polarizer and the slow axis direction of the 1/4 wavelength layer are 75 degrees.

In addition, the thickness of the retardation layer based on the above-mentioned coating is 1.2 micrometers in a 1/4 wavelength layer, and is 2.3 micrometers in a 1/2 wavelength layer. The thickness of the adhesive layer is 3 μm.

Examples 1 to 18

On the base film shown in Table 2, a polarizing plate and a retardation layer were provided using the method shown in Table 2 to prepare a circularly polarizing plate.

Comparative example 1

After laminating the polarizing plate on the base film using the polarizing plate lamination method D, a TAC film with a thickness of 80 μm was bonded to the polarizing plate using a PVA adhesive to prepare a polarizing plate. Further, a phase difference layer is provided on the TAC film of the polarizing plate using the retardation layer stacking method I to prepare a circularly polarizing plate.

Comparative example 2

After laminating the polarizing plate on the base film using the polarizing plate laminating method A, a 1/2-wavelength film is laminated on the polarizing plate, and a 1/4-wavelength film is further laminated on the polarizing plate. The 1/2 wavelength film was used so that the thickness of the 1/4 wavelength film was doubled, and each lamination was performed according to the lamination method I of the retardation layer. The absorption axis of the 1/2 wavelength plate with respect to the polarizing plate was set to 15 degrees, and the absorption axis of the 1/4 wavelength layer with respect to the polarizing plate was set to 75 degrees.

Table 2 shows the characteristics of the circularly polarizing plates obtained in Examples 1 to 18 and Comparative Examples 1 to 2. In addition, all anti-reflection effects are ○. In addition, when the EL display device used for evaluating the anti-reflection effect was visually observed without using polarized sunglasses, no rainbow spots were observed in the EL display device having the circularly polarizing plate of each example, and good visibility was obtained. .

[Table 2]

Furthermore, Table 3 shows the flexibility characteristics of the circularly polarizing plates obtained in Examples 1 to 18 and Comparative Examples 1 to 2.

[table 3]

(Preparation of coating for circularly polarized light reflective layer)

A methyl ethyl ketone/cyclohexanone (95/5 mass ratio) solution with a solid content concentration of 5% was prepared as follows.

·LC242 (manufactured by BASF Co., Ltd.) 100 parts by mass

·LC756 (manufactured by BASF Co., Ltd.) 5 parts by mass

·Irgacure 819 4 parts by mass

·0.75 parts by mass of the following fluorine-containing compound (1)

·0.075 parts by mass of the following fluorine-containing compound (2)

(Formation of circularly polarized light reflective layer)

The coating material for the circularly polarized light reflecting layer was applied to the phase difference layer of the circularly polarizing plate obtained in the Example using a bar coater, and dried at 85°C. Next, ultraviolet rays were irradiated in an oven at 85° C. to form a circularly polarized light reflective layer.

(Evaluation of circularly polarizing plates laminated with circularly polarized light reflecting layers)

The circularly polarizing plate on which the circularly polarized light reflection layer obtained above was laminated was similarly installed in an EL display and visually observed. The results were compared with the circularly polarizing plate of each example in which the circularly polarized light reflection layer was not laminated. to improve brightness.

In addition, the operability and bending resistance were similarly evaluated, and the results were found to be at the same level as those of the original examples.

The EL display device of the present invention uses a base film with a specific in-plane retardation, sets the number of self-standing films between the polarizer and the retardation layer to one or less, uses a 1/2 wavelength layer and 1 The /4 wavelength layer circular polarizing plate serves as a phase difference plate, so it has excellent visibility (suppresses rainbow spots), can be thinned, and is less likely to cause trouble in the manufacturing process.

In addition, when a flexible EL display device is formed, the laminated members are not easily peeled off from each other and creases are not easily formed when the EL display device is repeatedly bent or left in a high-temperature state.

When a polyester film is further used as the base film of the circularly polarizing plate, an EL display device having a circularly polarizing plate excellent in moisture permeability resistance, dimensional stability, mechanical strength, and chemical stability can be provided.

Claims (11)

1. An electroluminescent display device, comprising: an electroluminescent element, and a circular polarizing plate disposed closer to the visible side than the electroluminescent element, The circular polarizing plate has a phase difference layer, a polarizing plate and a base film in sequence, (1) The base film is a polyethylene terephthalate film with an in-plane retardation of 3000 to 30000 nm; (2) There is no self-standing film between the polarizer and the retardation layer, or there is only one self-standing film. Here, the space between the polarizer and the retardation layer also includes the retardation layer itself; (3) The phase difference layer has a 1/2 wavelength layer and a 1/4 wavelength layer; (4) The thickness of the circularly polarizing plate is 130μm or less; and, (5) The angle between the transmission axis of the polarizing plate and the slow axis of the base film is 10 degrees or less. 2. The electroluminescent display device according to claim 1, wherein the base film has a thickness of 50 to 100 μm. 3. The electroluminescence display device according to claim 1 or 2, wherein the thickness of the circular polarizing plate is 100 μm or less. 4. The electroluminescence display device according to claim 1, wherein the thickness of the polarizing plate is 12 μm or less. 5. The electroluminescence display device according to claim 1 or 2, wherein the polarizing plate is formed of a polymerizable liquid crystal compound and a dichroic dye. 6. The electroluminescent display device according to claim 1 or 2, wherein at least one of the 1/2 wavelength layer and the 1/4 wavelength layer is formed of a liquid crystal compound. 7. The electroluminescent display device according to claim 1 or 2, wherein a self-supporting film is not present between the polarizing plate and the retardation layer. 8. The electroluminescent display device according to claim 7, wherein both the 1/2 wavelength layer and the 1/4 wavelength layer are formed of a liquid crystal compound. 9. The electroluminescent display device according to claim 1 or 2, wherein the electroluminescent display device is a folding type electroluminescent display device or a roll-type electroluminescent display device. 10. The electroluminescent display device according to claim 1 or 2, wherein the electroluminescent display device is a foldable type, The display part is arranged on the inner side of the fold, The angle between the main orientation direction of the base film and the folding direction is 75 to 105 degrees. 11. The electroluminescent display device according to claim 1 or 2, wherein the electroluminescent display device is a foldable type, The display part is arranged on the outer side of the fold, The angle between the main orientation direction of the base film and the folding direction is 15 degrees or less.