CN111869323B

CN111869323B - Electroluminescent display device

Info

Publication number: CN111869323B
Application number: CN201980019195.5A
Authority: CN
Inventors: 柴野博史; 山下达郎; 村田浩一; 中瀬胜贵; 早川章太; 佐佐木靖; 本乡有记; 西尾正太郎
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2018-03-23
Filing date: 2019-03-22
Publication date: 2023-07-25
Anticipated expiration: 2039-03-22
Also published as: TW201940906A; WO2019182120A1; KR20200133786A; CN111869323A; TWI814797B; JP2019169470A; JP7259452B2

Abstract

An electroluminescent display device, comprising: an electroluminescent element, and a circularly polarizing plate disposed on the visual side of the electroluminescent element, the circularly polarizing plate comprising a retardation layer, a polarizing plate, and a base film in this order, (1) the refractive index ny of the base film in the fast axis direction is 1.568 or more and 1.63 or less; (2) There is no independent film or only 1 independent film between the polarizer and the retardation layer (here, the retardation layer itself is also included between the polarizer and the retardation layer); and, (3) the transmission axis of the polarizer is substantially parallel to the fast axis of the substrate film.

Description

Electroluminescent display device

Technical Field

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

Background

In the EL display device, external light is reflected on the surface of a constituent material such as an image display element and a touch sensor, and on these wiring portions, and the visibility is lowered. For these problems, the following methods have been proposed: an optical laminate is disposed on the exit surface of the image display device to reduce reflection of external light. The optical laminate is generally a circular polarizing plate in which a linear polarizing plate and a 1/4 wavelength retardation plate are laminated.

As a polarizer protective film for a polarizing plate, a polyester film having an in-plane retardation of 3000 to 30000nm has been proposed (for example, see patent document 1). Polyester films are suitable for use in image display devices because they have lower moisture permeability, excellent mechanical properties (high impact resistance and high elastic modulus), and further excellent chemical properties (solvent resistance, etc.) than cellulose-based or acrylic films. However, the polyester film has birefringence, and thus has a disadvantage that rainbow spots are easily generated. Thus, in order to use a polyester film, suppress rainbow unevenness and provide a sufficient in-plane retardation, it is necessary to thicken the film.

Further, in order to obtain a circularly polarizing plate having better color reproducibility by suppressing the influence of the wavelength dispersibility of the refractive index, a technique of combining a 1/4 wavelength plate and a 1/2 wavelength plate has been proposed (patent document 2). However, when such a plurality of retardation plates are laminated on the polarizing plate, the problem of the thickness becomes more remarkable. Further, since a plurality of films are laminated on a circular polarizing plate, when the circular polarizing plate is wound and stored in a manufacturing process, curling is easily applied, and handling in a subsequent bonding process with an EL element is sometimes difficult.

In this way, the circularly polarizing plate in which the retardation plate is laminated on the polarizing plate having the base film with high retardation as the protective film has a thickness, and therefore, there is a problem that it is not sufficient to cope with the recent demand for thinning and trouble is likely to occur in the manufacturing process. In particular, in a large-sized image display device of more than 40 types (40 inches in length along the diagonal line of the display portion), the circularly polarizing plate is also large, and curling is likely to occur.

In recent years, as an image display device, a flexible EL display device has been proposed which has a wide display surface and is folded in a V-shape, a zigzag shape, a W-shape, a double door shape, or the like when carried, or which can be wound in a roll shape. In such a foldable (foldable) or reelable (rollable) EL display device, if a circularly polarizing plate is used, there are the following problems: sufficient bending performance cannot be obtained due to the thickness thereof; the film is easily peeled off when the bending operation is repeated or the film is placed in a high temperature place such as the interior of an automobile; the bending trace is easily given.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2012-256057

Patent document 2: japanese patent laid-open No. 10-68816

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above-described problems of the prior art. That is, an object of the present invention is to provide: an EL display device which is thin, hardly causes trouble in the manufacturing process, and is flexible, and in which members laminated by repeated bending or by being placed in a high temperature state are hardly peeled off from each other, and crease is hardly given, while ensuring visibility.

Solution for solving the problem

The present inventors have conducted intensive studies to develop an EL display device which is thin while ensuring visibility, is less likely to cause trouble in the production process, is flexible, and is less likely to cause peeling of members laminated when the EL display device is repeatedly bent or placed in a high temperature state, and is less likely to cause creases, and as a result, have found that: the above object can be achieved by using a circularly polarizing plate in which a base film having a refractive index ny in the fast axis direction of a specific value is used, and the number of independent films existing between a polarizing plate and a retardation layer is 1 or less, and the light transmission axis of the polarizing plate and the fast axis of the base film are substantially parallel. The present invention has been completed based on such an insight.

That is, the present invention relates to the EL display device shown in the items 1 to 6.

Item 1.

An electroluminescent display device, comprising: an electroluminescent element, and a circularly polarizing plate disposed on the visible side of the electroluminescent element,

the circular polarizing plate comprises a retardation layer, a polarizing plate and a base film in this order,

(1) The refractive index ny of the substrate film in the fast axis direction is 1.568 or more and 1.63 or less;

(2) There is no independent film or only 1 independent film between the polarizer and the retardation layer (here, the retardation layer itself is also included between the polarizer and the retardation layer); and, a step of, in the first embodiment,

(3) The transmission axis of the polarizer is substantially parallel to the fast axis of the substrate film.

Item 2.

The electroluminescent display device according to item 1, wherein the in-plane birefringence Δnxy of the base material film is 0.06 or more and 0.2 or less.

Item 3.

The electroluminescent display device according to item 1 or 2, wherein the lower of the tear strength in the slow axis direction and the fast axis direction of the base film by the rectangular tearing method has a value of 250N/mm or more.

Item 4.

The electroluminescent display device according to any one of the above items 1 to 3, wherein the thickness of the polarizing plate is 12 μm or less.

Item 5.

The electroluminescent display device according to any one of the above items 1 to 4, wherein the polarizing plate is formed of a polymerizable liquid crystal compound and a dichroic dye.

Item 6.

The electroluminescent display device according to any one of the above items 1 to 5, wherein the retardation layer is formed of a liquid crystal compound.

ADVANTAGEOUS EFFECTS OF INVENTION

In the EL display device of the present invention, a base film having a refractive index ny in the fast axis direction of 1.568 or more and 1.63 or less is used as a circularly polarizing plate, and the number of the self-supporting films existing between the polarizing plate and the retardation layer is 1 or less, and the light transmission axis of the polarizing plate and the fast axis of the base film are substantially parallel to each other, so that the visibility is excellent (suppression of rainbow unevenness) and the thickness can be reduced, and trouble is not easily caused in the manufacturing process.

In addition, in the case of a flexible EL display device, the members laminated by repeated bending or by being placed in a high temperature state are not easily peeled off from each other, and a crease is not easily given.

Detailed Description

An EL display device of the present invention includes: an EL element, and a circularly polarizing plate disposed on the visible side of the EL element. By disposing the circularly polarizing plate on the viewing surface of the EL display device, it is possible to reduce the possibility of reducing visibility by external light reflected on the surface of the EL element or on the wiring. The EL display device of the present invention is thin. The circularly polarizing plate has a retardation layer, a polarizing plate, and a base film in this order.

First, a circular 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 this order. In this circularly polarizing plate, the retardation layer, the polarizing plate, and the base film are basically laminated in this order, but the concept of having other layers between the layers is also included.

A. Circular polarizing plate

1. Substrate film

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

(Material of base film)

The resin used in the base film of the present invention is not particularly limited as long as it is oriented to cause birefringence. In terms of increasing the retardation, polyester, polycarbonate, polystyrene, and the like are preferable, and polyester is more preferable. Preferred polyesters include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), and among these, PET and PEN are more preferred. By using a polyester film as a base film, an EL display device having a circularly polarizing plate excellent in moisture permeation 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 1.5dL/g. The lower limit of IV is more preferably 0.6dL/g, still more preferably 0.65dL/g, particularly preferably 0.68dL/g. The upper limit of IV is more preferably 1.2dL/g, still more preferably 1dL/g. If the IV of PET is less than 0.58dL/g, bending marks may be easily imparted by repeated bending. If the IV of PET exceeds 1.5dL/g, the film may be difficult to manufacture. The Intrinsic Viscosity (IV) used in the present invention was the value obtained as follows: will be described as 6:4, and a value measured at a temperature of 30 ℃ while mixing phenol with 1, 2-tetrachloroethane as a solvent.

The light transmittance of the substrate film at a wavelength of 380nm is desirably 20% or less. The transmittance at a wavelength of 380nm is more preferably 15% or less, still more preferably 10% or less, particularly preferably 5% or less. If the light transmittance is 20% or less, deterioration of iodine or a dichroic dye in the polarizing plate due to ultraviolet rays can be suppressed. The transmittance in the present invention is measured in a direction perpendicular to the plane of the film, and may be measured using a spectrometer (for example, japanese U-3500 type).

In order to achieve a light transmittance of 20% or less at a wavelength of 380nm of the base film, the following method is used: adding an ultraviolet absorber into the substrate film; coating a coating liquid containing an ultraviolet absorber on the surface of a substrate film; the type or concentration of the ultraviolet absorber and the thickness of the substrate film are properly adjusted; etc. In the present invention, a substance known in the art can be used as the ultraviolet absorber. Examples of the ultraviolet absorber include organic ultraviolet absorbers and inorganic ultraviolet absorbers. From the viewpoint of transparency, an organic ultraviolet absorber is preferable.

The organic ultraviolet absorber is not particularly limited as long as the transmittance of the substrate film at 380nm is 20% or less. Examples of such an organic ultraviolet absorber include: benzotriazole, benzophenone, cyclic imino ester, and the like, and combinations thereof.

In order to improve slidability, it is preferable to add particles having an average particle diameter of 0.05 to 2. Mu.m. Examples of the particles include inorganic particles such as titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, calcium phosphate, mica, hectorite, zirconium oxide, tungsten oxide, lithium fluoride, and calcium fluoride; and organic polymer particles such as styrene-based, acrylic-based, melamine-based, benzoguanamine-based, and silicone-based. The average particle diameter was calculated by observing particles having a cross section of a thin film with a scanning electron microscope. Specifically, 100 particles in a cross section of the film were observed by a scanning electron microscope, and the diameters (d) of the respective particles were measured, and the average value thereof was taken as the average particle diameter.

These particles may be added to the whole substrate film. Alternatively, the substrate may be formed into a sheath-core co-extruded multilayer structure with particles added only to the sheath.

The lower limit of the refractive index ny in the fast axis direction of the base film is preferably 1.568, more preferably 1.578, further preferably 1.584, particularly preferably 1.588. The upper limit of the refractive index ny in the fast axis direction of the substrate film is preferably 1.63, more preferably 1.62, further preferably 1.615, particularly preferably 1.61. In the case of the PET film, ny is close to the perfect uniaxiality (uniaxial symmetry) if it is less than 1.58, and therefore, the mechanical strength in the direction parallel to the orientation direction is significantly lowered. In addition, in the film with ny of more than 1.62, rainbow-like color spots are easily observed when viewed from an oblique direction.

In general, a polyvinyl alcohol or a polymerizable liquid crystal compound is used as a matrix material for a polarizing plate. In the above case, although it is uncertain, the reason why rainbow unevenness is not easily observed is that the refractive index of these polarizers in the light transmission axis direction is close to the refractive index of the base film, and reflection at the interface is suppressed.

The in-plane birefringence Δnxy of the substrate film is preferably 0.06 or more and 0.2 or less, more preferably 0.07 or more and 0.19 or less, and still more preferably 0.08 or more and 0.18 or less. If Δnxy is less than 0.06, rainbow-like color spots are easily observed when viewed from an oblique direction. Further, in the film having Δnxy of more than 0.2, rainbow-like color spots are not generated, but as described above, the film is nearly completely uniaxial (uniaxially symmetric), and therefore, the mechanical strength in the direction parallel to the orientation direction is significantly reduced.

The in-plane birefringence Δnxy is the absolute value of the difference between the refractive index (nx) in the slow axis direction and the refractive index (ny) in the fast axis direction. The refractive index measurement wavelength was 589nm.

The lower of the tear strength in the slow axis direction and the fast axis direction of the base film by the rectangular tearing method has a value of preferably 250N/mm or more, more preferably 280N/mm or more, still more preferably 300N/mm or more. In the film having a high value of Δnxy, the value of tear strength in the slow axis direction tends to be smaller than that in the fast axis direction. When the tear strength is less than 250N/mm, the film is easily broken, and the stability at the time of film formation or processing is lowered. On the other hand, the higher the tear strength, the more stable the film is formed or processed, but the higher the biaxial properties (biaxial symmetry) become, and the iridescent stain is generated. Therefore, the tear strength is preferably improved within a range where iridescent stains are not generated, and in reality, 500N/mm or less is preferable.

The tear strength was as follows: the tear strength (N/mm) per film thickness was determined by measuring according to the Right angle tear method (JISK-7123).

The Nz coefficient of the base film is preferably 1.5 or more and 2.5 or less, more preferably 1.6 or more and 2.3 or less, and still more preferably 1.7 or more and 2.1 or less. The smaller the Nz coefficient, the less likely the iridescent stain is generated by the observation angle. In addition, in the completely uniaxial (uniaxially symmetric) film, the Nz coefficient becomes 1. However, as described above, the mechanical strength tends to decrease in the direction parallel to the orientation direction with the approach to a completely uniaxial (uniaxially symmetric) film.

The Nz coefficient can be obtained as follows. The orientation major axis direction (slow axis direction) of the film was determined by a molecular orientation meter (model MOA-6004, manufactured by Oji Scientific Instruments Co ltd.) and the biaxial refractive index (slow axis direction refractive index nx, fast axis direction refractive index ny, where nx > ny) and the thickness direction refractive index (nz) of the orientation major axis direction and the direction orthogonal thereto (fast axis direction) were determined by an abbe refractive index meter (ATAGO co., manufactured by ltd., NAR-4T, measurement wavelength 589 nm). The thus obtained nx, ny and Nz are substituted into the expression of |nx-nz|/|nx-ny| to obtain the Nz coefficient. The refractive index measurement wavelength was 589nm.

From the viewpoint of further reducing the rainbow unevenness, the base film preferably has a retardation of 1500 to 9000nm. The lower limit of the retardation is preferably 2000nm, more preferably 2500nm.

On the other hand, the upper limit of the retardation is preferably 9000nm. Even if a base film having a retardation exceeding that is used, not only is a further improvement effect of visibility substantially not obtained in organic EL display devices widely used in flexible image display devices, but also the thickness of the base film becomes thick, and the operability as a circularly polarizing plate for thin flexible image display devices is lowered, or crease may be easily imparted by repeated folding operations caused by long-time use. The preferable upper limit of the retardation amount is 8000nm, more preferable upper limit is 6000nm, further preferable upper limit is 5500nm, and most preferable upper limit is 5000nm.

The birefringence may be obtained by measuring the refractive index in the 2-axis direction, or may be obtained by using a commercially available automatic birefringence measuring apparatus such as KOBRA-21ADH (Oji Scientific Instruments Co ltd.). The refractive index measurement wavelength was 589nm.

The base film used in the present invention can be obtained by a general method for producing a film from each raw material. Hereinafter, a case where the base film is polyester will be described as an example. A polyester base film (hereinafter, may be simply referred to as a base film) can be produced by a general method for producing a polyester film. Examples of the method for producing the polyester film include the following: the polyester resin is melted, extruded into a sheet shape and molded to obtain an unoriented polyester, and the unoriented polyester obtained is stretched in the machine direction and the transverse direction at a temperature equal to or higher than the glass transition temperature, and subjected to heat treatment.

The base film may be a uniaxially stretched film or a biaxially stretched film. When a biaxially stretched film is used as a base film, if the biaxially properties are increased, no rainbow-like color spots are observed from directly above the film surface, but rainbow-like color spots are sometimes observed when the film is observed from an oblique direction, and therefore, attention is required.

This phenomenon is caused as follows: the biaxially stretched film is composed of refractive index ellipsoids having different refractive indices in the advancing direction, the width direction and the thickness direction, and there is a direction in which the retardation becomes zero (the viewing refractive index ellipsoids are perfect circles) depending on the transmitting direction of light at the inside of the film, thereby causing this. Therefore, if the display screen is viewed from a specific direction of the oblique direction, there is a case where a point where the retardation becomes zero is generated, and the rainbow-like color spots are generated concentrically around the point. When the angle from the position directly above (in the normal direction) the film surface to the position where the iridescent stain is visible is defined as θ, the angle θ increases as the birefringence in the film surface increases, and the iridescent stain is less visible. In the biaxially stretched film, the angle θ tends to be smaller, and therefore, it is preferable in that it is difficult to observe iridescent stains as compared with the uniaxially stretched film.

However, a completely uniaxial (uniaxially symmetric) film is not preferable because the mechanical strength in the direction perpendicular to the orientation direction is significantly reduced. In the present invention, it is preferable that the liquid crystal display device has biaxial properties (biaxial symmetry) in a range where substantially no iridescent stains are generated or in a range where iridescent stains are not generated in a viewing angle range required for a liquid crystal display screen.

The main orientation axis (slow axis in the case of polyester) of the base film may be the advancing direction (longitudinal direction, MD direction) of the film, or may be a direction perpendicular to the longitudinal direction (perpendicular direction, TD direction).

The film forming conditions of the base film may be sequential biaxial stretching or simultaneous biaxial stretching. First, a film forming method in sequential biaxial stretching will be described.

First, when the slow axis is in the orthogonal direction, the molten PET is extruded onto a cooling roll, and the obtained unstretched preform is longitudinally stretched by a continuous roll. Then, both ends of the film were fixed with a jig and introduced into a tenter, and after preheating, stretching was performed in the transverse direction while heating. In the case where the slow axis is the longitudinal direction, the same procedure as described above is possible, but it is preferable to stretch the unstretched blank in the transverse direction in the tenter and then to stretch it longitudinally with continuous rolls.

The longitudinal stretching temperature and the transverse stretching temperature are preferably 80 to 130 ℃, more preferably 90 to 120 ℃. The stretching ratio in the direction perpendicular to the main orientation direction to be first performed is preferably 1.2 to 3 times, more preferably 1.8 to 2.5 times. The stretching ratio in the main orientation direction is preferably 2.5 to 6 times, more preferably 3 to 5.5 times.

In general, in sequential biaxial stretching, longitudinal stretching is roll stretching, and therefore scratches are easily imparted to a film. Therefore, from the viewpoint of preventing scratches at the time of stretching, simultaneous biaxial stretching without using rolls is preferable. When the conditions for simultaneous biaxial stretching are specifically described, the longitudinal stretching temperature and the transverse stretching temperature are preferably 80 to 150 ℃, more preferably 90 to 140 ℃. When the slow axis direction is the longitudinal direction, the longitudinal stretching ratio is preferably 5.5 to 7.5 times, more preferably 6 to 7 times, particularly preferably 6.5 to 7 times. The lateral stretching ratio is preferably 1.5 to 3 times, more preferably 1.8 to 2.8 times. When the slow axis direction is orthogonal, the longitudinal stretching ratio and the transverse stretching ratio are opposite to each other.

In the case of uniaxial stretching, stretching may be performed only in the slow axis direction in the above.

In addition, from the viewpoint of making it difficult to impart scratches to the film and from the viewpoint of enabling the use of general stretching equipment, it may be monoaxial stretching only in the transverse direction by a tenter.

In order to control the slow axis direction, Δnxy, nz coefficient, and tear strength to the above ranges, it is preferable to control the respective magnifications of the longitudinal stretching magnification and the transverse stretching magnification. If the difference in longitudinal and lateral stretching ratios is too small, it becomes difficult to increase Δnxy. In addition, setting the stretching temperature lower is also preferable in terms of increasing Δnxy.

In order to improve the tear strength, it is preferable to appropriately impart biaxial properties under the condition that Δnxy satisfies the range defined in the present specification, as compared with a completely uniaxial film.

In the subsequent heat treatment, the treatment temperature is preferably 100 to 250 ℃, more preferably 180 to 245 ℃.

The thickness of the base film is arbitrary, preferably in the range of 15 to 90. Mu.m, more preferably in the range of 15 to 80. Mu.m. In the base film having a thickness of less than 15 μm, the mechanical properties of the film are remarkably reduced, and breakage, cracking, and the like are liable to occur, which tends to remarkably reduce the practical applicability. The particularly preferred lower limit of the thickness is 20. Mu.m. On the other hand, if the upper limit of the thickness of the base film exceeds 90. Mu.m, the thickness of the circularly polarizing plate becomes thick, which is not preferable. Further, since marks are easily provided by repeated bending with a small radius, the upper limit of the thickness is preferably 80 μm, more preferably 70 μm, still more preferably 60 μm, and particularly preferably 50 μm.

In the above thickness range, in order to control Δnxy, nz coefficient and tear strength to the ranges of the present invention, polyethylene terephthalate is suitable as the polyester for the base film.

In addition, as a method of compounding an ultraviolet absorber into the polyester film in the present invention, a known method may be used in combination. For example, an ultraviolet absorber may be compounded in a polyester film by the following method or the like: the dried ultraviolet absorber is blended with the polymer raw material in advance by a kneading extruder to prepare a master batch in advance, and the master batch and the polymer raw material are mixed at a predetermined ratio at the time of film formation.

In the above case, the concentration of the ultraviolet absorber in the master batch is preferably 5 to 30 mass% in order to uniformly disperse and economically blend the ultraviolet absorber. As the conditions for producing the master batch, it is preferable to use a kneading extruder and extrude the master batch at a temperature of not less than the melting point of the polyester raw material and not more than 290℃for 1 to 15 minutes. If the extrusion temperature exceeds 290 ℃, the reduction in the amount of the ultraviolet absorber is large, and the viscosity of the master batch is also reduced. If the extrusion time is less than 1 minute, uniform mixing of the ultraviolet absorber becomes difficult. In this case, a stabilizer, a color tone regulator, an antistatic agent, and the like may be added as necessary.

In the present invention, it is preferable that the film has a multilayer structure of at least 3 layers, and an ultraviolet absorber is added to the intermediate layer of the film. Specifically, a film having a 3-layer structure in which the intermediate layer contains an ultraviolet absorber can be produced as follows. Pellets of polyester were used alone as the outer layer, and a master batch containing an ultraviolet absorber for the intermediate layer and pellets of polyester were mixed at a predetermined ratio, dried, fed into a known extruder for melt lamination, extruded from a slit die into a sheet form, and cooled and solidified on a casting roll to obtain an unstretched film. That is, the film layers constituting the two outer layers and the film layer constituting the intermediate layer are laminated by using 2 or more extruders, a 3-layer manifold or a junction block (for example, a junction block having a square junction), 3-layer sheet is extruded from a die head, and cooled on a casting roll to obtain an unstretched film. In the present invention, it is preferable to perform high-precision filtration at the time of melt extrusion in order to remove foreign matters contained in the polyester as a raw material which causes optical defects. The filter medium used for high-precision filtration of the molten resin preferably has a filter particle size (initial filtration efficiency 95%) of 15 μm or less. By setting the filter medium to have a filter particle size of 15 μm or less, foreign matter having a particle size of 20 μm or more can be sufficiently removed.

The base film may be subjected to a treatment for improving adhesion such as corona treatment, flame treatment, and plasma treatment.

(easy adhesive layer)

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

Examples of the resin used for the easy-to-adhere layer include polyester resins, polyurethane resins, polyester polyurethane resins, polycarbonate polyurethane resins, and acrylic resins, and among these, polyester resins, polyester polyurethane resins, polycarbonate polyurethane resins, and acrylic resins are preferable. The easy-to-adhere layer is preferably crosslinked. Examples of the crosslinking agent include isocyanate compounds, melamine compounds, epoxy resins, and oxazoline compounds. In addition, in order to improve adhesion, a resin similar to the resin used for the alignment layer or the polarizing film, such as polyvinyl alcohol, polyamide, polyimide, and polyamideimide, is also useful means.

The easy-to-adhere layer may be provided as follows: the aqueous coating material to which these resins, and if necessary, a crosslinking agent, particles, and the like are added is formed, and the aqueous coating material is applied to a base film and dried, thereby providing the aqueous coating material. As the particles, the user in the above-mentioned base material can be exemplified.

The easy-to-adhere layer may be provided on the stretched base film off-line, or on-line in the film forming step. The easy-to-adhere layer is preferably provided in-line in the film-forming step. When the easy-to-adhere layer is provided in-line, it may be either before longitudinal stretching or before transverse stretching. In particular, it is preferable that the water-based paint is applied immediately before the transverse stretching, preheated and heated by a tenter, and dried and crosslinked in the heat treatment step, so that the adhesive layer is provided in-line. In the case of performing in-line coating immediately before longitudinal stretching by a roll, it is preferable that the aqueous coating material is applied, dried in a vertical dryer, and then introduced into a stretching roll.

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

(functional layer)

It is also preferable to provide a functional layer such as a hard coat layer, an antireflection layer, a low reflection layer, an antiglare layer, or an antistatic layer on the side of the base film opposite to the side on which the polarizing film is laminated.

The thickness of the functional layer can be suitably set, and is preferably 0.1 to 50. Mu.m, more preferably 0.5 to 20. Mu.m, and still more preferably 1 to 10. Mu.m. It should be noted that these layers may be provided in a plurality of layers.

In the case of providing the functional layer, an easy-to-adhere layer (easy-to-adhere layer P2) may be provided between the functional layer and the base film. The adhesive layer P2 may be suitably formed of a resin, a crosslinking agent, or the like listed in the adhesive layer P1. The easy-to-adhere layer P1 and the easy-to-adhere layer P2 may have the same composition or may have different compositions.

The easy-to-adhere layer P2 is also preferably provided in-line. The easy-to-adhere layer P1 and the easy-to-adhere layer P2 may be formed by sequentially coating and drying them. It is also preferable to apply the easy-to-adhere layer P1 and the easy-to-adhere layer P2 simultaneously on both sides of the base film.

In the following description, the term "substrate film" includes not only the case where the easy-to-adhere layer is not provided but also the case where the easy-to-adhere layer is provided. Similarly, the substrate film is also provided with a functional layer.

2. Polarizing plate

In the circularly polarizing plate used in the present invention, a polarizing plate is provided on a 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 a polarizing film may be provided thereon. In the present invention, the alignment layer and the polarizing film may be collectively referred to as a polarizing plate. In the case where the polarizing film is provided without an alignment layer on the base film, the polarizing film may be referred to as a polarizing plate.

(polarizing film)

The polarizing film has a function of passing polarized light only in one direction. The polarizing film may be used without particular limitation: a stretched film such as polyvinyl alcohol (PVA) and the like, a film obtained by blending iodine or a dichroic dye with a stretched film, a dichroic dye film or a polymerizable liquid crystal compound, a coated film obtained by blending a dichroic dye with a stretched film of polyene, a wire grid, and the like.

Among them, a polarizing film having iodine adsorbed on PVA and a polarizing film having a dichroic dye blended in a polymerizable liquid crystal compound are preferable.

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

The polarizing film having iodine adsorbed in PVA can be generally obtained as follows: the uniaxially stretched film of PVA may be obtained by immersing the film in a bath containing iodine and then uniaxially stretching the film, or by immersing the uniaxially stretched film in a bath containing iodine and then crosslinking the film in a boric acid bath.

The thickness of the polarizing film obtained by the above method is preferably 1 to 30. Mu.m, more preferably 1.5 to 20. Mu.m, still more preferably 2 to 15. Mu.m. If the thickness of the polarizing film is less than 1 μm, sufficient polarizing characteristics cannot be exhibited, and too thin may become difficult to handle. If the thickness of the polarizing film exceeds 30. Mu.m, the object of the thickness reduction is not satisfied.

When the polarizing film having iodine adsorbed in PVA is laminated on the base film, the base film is preferably bonded to the polarizing film. As the adhesive for adhesion, a conventional adhesive for use by a user can be used without limitation. Among them, PVA-based aqueous adhesives, ultraviolet-curable adhesives, and the like are preferable, and ultraviolet-curable adhesives are more preferable.

In this way, the polarizing film having iodine adsorbed to PVA can be laminated with the base film using a film alone as a polarizing plate. Alternatively, the layers may be laminated by: a polarizing film was transferred to a substrate film using a polarizing plate (a polarizing plate laminated to a release support substrate) laminated to a release support substrate obtained by applying PVA to the release support substrate and stretching the PVA in this state. The lamination method by transfer is also preferable as a lamination method of a polarizing plate and a base film, in the same manner as the above-described adhesion method. In the case of using this transfer method, the thickness of the polarizing plate is preferably 12 μm or less, more preferably 10 μm or less, still more preferably 8 μm or less, particularly preferably 6 μm or less. Even in such a very thin polarizing plate, since the polarizing plate is a releasable support substrate, handling is easy, and the polarizing plate can be easily laminated on a substrate film. By using such a thin polarizing plate, the thickness can be further reduced, and flexibility can be ensured.

Techniques for laminating a polarizing plate and a base film are known, and for example, refer to japanese patent application laid-open No. 2001-350021, japanese patent application laid-open No. 2009-93074, and the like.

A method of laminating a polarizing plate and a base film by transfer printing will be specifically described. First, PVA is coated on a releasable supporting substrate of a thermoplastic resin which is not stretched or is uniaxially stretched perpendicular to the longitudinal direction, and a laminate of the obtained releasable supporting substrate of a thermoplastic resin and PVA is stretched to 2 to 20 times, preferably 3 to 15 times in the longitudinal direction. The stretching temperature is preferably 80 to 180℃and more preferably 100 to 160 ℃. Next, the stretched laminate is immersed in a bath containing a dichroic dye, and the dichroic dye is adsorbed. Examples of the dichroic dye include iodine and organic dyes. When iodine is used as the dichroic dye, an aqueous solution containing iodine and potassium iodide is preferably used as the dyeing bath. Then, the aqueous solution immersed in boric acid is treated, washed with water, and dried. The stretching may be performed 1.5 to 3 times before the adsorption of the dichroic dye as the pre-stretching. The above-described method is an example, and the adsorption of the dichroic dye may be performed before the stretching, or the treatment with boric acid may be performed before the adsorption of the dichroic dye. Stretching may be performed in a bath containing a dichroic dye or in a bath of an aqueous boric acid solution. The steps may be performed in a combination of multiple stages.

As the release support substrate (release film) for the thermoplastic resin, a polyester film such as polyethylene terephthalate, a polyolefin film such as polypropylene and polyethylene, a polyamide film, a polyurethane film, and the like can be used. The release force can be adjusted by subjecting the release support substrate (release film) of the thermoplastic resin to corona treatment, or providing release coating, easy-to-adhere coating, or the like.

The polarizing plate surface of the polarizing plate is laminated with a releasable supporting substrate, and then the releasable supporting substrate is peeled off to obtain a laminate of the polarizing plate and the substrate film. The thickness of the adhesive used is usually 5 to 50 μm and the adhesive is 1 to 10. Mu.m. For the purpose of thickness reduction, an adhesive is preferably used, and among them, an ultraviolet-curable adhesive is more preferably used. From the standpoint of the process without requiring a special device, it is also preferable to use an adhesive.

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

The dichroic dye is a dye having a property that 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 a dichroic dye include organic dichroic dyes such as acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes, and among them, azo dyes are preferable. The azo dye may be a monoazo dye, a disazo dye, a trisazo dye, a tetrazo dye, a stilbene azo dye, or the like, and among them, a disazo dye and a trisazo dye are preferable. The dichroic dye may be used alone or in combination. In order to adjust the (achromatic) color tone, 2 or more combinations are preferable, and 3 or more combinations are more preferable. In particular, 3 or more azo compounds are preferably used in combination.

Preferred azo compounds include pigments described in Japanese patent application laid-open No. 2007-126628, japanese patent application laid-open No. 2010-168870, japanese patent application laid-open No. 2013-101328, japanese patent application laid-open No. 2013-210624, and the like.

The dichroic dye is also a preferable mode of a dichroic dye polymer introduced into a side chain of a polymer such as an acrylic. Examples of the dichroic dye polymers include polymers described in JP 2016-4055, and polymers obtained by polymerizing compounds of [ chemical formulae 6] to [ chemical formulae 12] of JP 2014-206682.

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

In order to improve film strength, polarization degree, film homogeneity, and the like, a polymerizable liquid crystal compound is contained in the polarizing film. The polymerizable liquid crystal compound also includes a substance polymerized in the form of a film.

The polymerizable liquid crystal compound is a compound having a polymerizable group and exhibiting liquid crystallinity.

The polymerizable group is a group participating in polymerization reaction, and is preferably a photopolymerizable group. The photopolymerizable group is a group that can undergo polymerization reaction by a living radical, an acid, or the like generated by a photopolymerization initiator described later. Examples of the polymerizable group include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, oxiranyl, oxetanyl, and the like. Among them, acryloyloxy, methacryloyloxy, ethyleneoxy, ethyleneoxide, and oxetanyl groups are preferable, and acryloyloxy is more preferable. The compound exhibiting liquid crystallinity may be a thermotropic liquid crystal or a lyotropic liquid crystal, or may be a nematic liquid crystal or a smectic liquid crystal among thermotropic liquid crystals.

The polymerizable liquid crystal compound is preferably a smectic liquid crystal compound, and more preferably a higher order smectic liquid crystal compound, in terms of obtaining higher polarization characteristics. If the liquid crystal phase formed by the polymerizable liquid crystal compound is a higher order smectic phase, a polarizing film having a higher alignment order can be produced.

Specific examples of the preferable polymerizable liquid crystal compound include those described in JP-A2002-308832, JP-A2007-16207, JP-A2015-163596, JP-A2007-510946, JP-A2013-114131, WO2005/045485, lub et al recl. Trav. Chim. Pays-Bas,115, 321-328 (1996), and the like.

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, still more preferably 80 to 97% by mass, and particularly preferably 83 to 95% by mass in the polarizing film, from the viewpoint of improving the alignment property of the polymerizable liquid crystal compound.

The polarizing film containing the polymerizable liquid crystal compound and the dichroic dye can be provided by coating a composition for polarizing film.

The composition for polarizing film may further contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a crosslinking agent, and the like in addition to the polymerizable liquid crystal compound and the dichroic dye.

The solvent may be used without limitation as long as the polymerizable liquid crystal compound is dissolved. Specific examples of the solvent include water; alcohol solvents such as methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, cellosolve, and the like; ester 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. These solvents may be used alone or in combination.

The polymerization initiator may be used without limitation as long as it polymerizes the polymerizable liquid crystal compound. As the polymerization initiator, a photopolymerization initiator that generates a living radical by light is preferable. Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkyl phenone compounds, acyl phosphine oxide compounds, triazine compounds, iodonium salts, sulfonium salts, and the like.

As the sensitizer, a photosensitizing agent is preferable. Examples of the photosensitizing agent include xanthone compounds, anthracene compounds, phenothiazine, rubrene, and the like.

Examples of the polymerization inhibitor include hydroquinones, catechols and thiophenols.

Examples of the leveling agent include various known surfactants.

The polymerizable non-liquid crystal compound is preferably a copolymer with a polymerizable liquid crystal compound. For example, when the polymerizable liquid crystal compound has a (meth) acryloyloxy group, the polymerizable non-liquid crystal compound may be (meth) acrylic esters. The (meth) acrylic acid esters may be monofunctional or polyfunctional. By using a multifunctional (meth) acrylate, the strength of the polarizing film can be improved. When the polymerizable non-liquid crystal compound is used, the content of the polymerizable non-liquid crystal compound in the polarizing film is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and still more preferably 3 to 7% by mass. If the content of the polymerizable non-liquid crystal compound exceeds 15 mass%, the degree of polarization may be lowered.

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

The composition for a polarizing film may be directly coated on a base film or an alignment layer, and then dried, heated and cured as needed, thereby providing a polarizing film.

As the coating method, a coating method such as a gravure coating method, a die coating method, a bar coating method, and an applicator method can be used; printing methods such as flexographic method and the like.

Drying is performed as follows: the coated substrate film is introduced into a hot air dryer, an infrared dryer, or the like, and is preferably carried out at 30 to 170 ℃, more preferably 50 to 150 ℃, and still more preferably 70 to 130 ℃. The drying time is preferably 0.5 to 30 minutes, more preferably 1 to 20 minutes, still more preferably 2 to 10 minutes.

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

The composition for polarizing film contains a polymerizable liquid crystal compound, and is therefore preferably cured. The curing method includes heating and light irradiation, and light irradiation is preferable. The fixing may be performed in a state where the dichroic dye is aligned by curing. The curing is preferably performed in a state where a liquid crystal phase is formed in the polymerizable liquid crystal compound, or may be performed by irradiation with light at a temperature at which the liquid crystal phase is exhibited.

Examples of the light to be irradiated include visible light, ultraviolet light, and laser beam. Ultraviolet light is preferable in terms of ease of operation.

The irradiation intensity varies depending on the kind or amount of the polymerization initiator or the resin (monomer), and is preferably 100 to 10000mJ/cm based on 365nm ² More preferably 200 to 5000mJ/cm ² 。

The polarizing film is formed by applying the composition for a polarizing film to an alignment layer provided as needed, and the pigment is aligned in the alignment direction of the alignment layer, and as a result, a polarizing transmission axis having a predetermined direction is obtained. When the composition for a polarizing film is directly applied to a substrate without providing an alignment layer, the composition for a polarizing film may be cured by irradiation with polarized light, so that the polarizing film may be aligned. It is further preferable that the dichroic dye is then heat treated to firmly orient the dichroic dye in the orientation direction of the polymer liquid crystal.

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

When a polarizing film containing a polymerizable liquid crystal compound and a dichroic dye is laminated on a base film, it is preferable to provide the polarizing film not only directly on the base film but also on another releasable film according to the above method, and transfer the polarizing film to the base film. The release film may be a release support substrate used in a release support substrate laminated polarizing plate laminated with the release support substrate, and particularly preferable examples thereof include a polyester film, a polypropylene film, and the like. The release film may be corona-treated, or release coated, or an easy-to-adhere coating may be provided, so that the release force may be adjusted.

The method of transferring the polarizing film to the substrate film is similar to the method of laminating a polarizing plate with a releasable supporting substrate as described above.

(alignment layer)

The polarizing plate used in the present invention may be constituted by combining a polarizing film and an alignment layer, as described above, in addition to a polarizing film.

The alignment layer is used for controlling the alignment direction of the polarizing film, and by providing the alignment layer, a polarizing plate having a higher degree of polarization can be provided.

The alignment layer may be any alignment layer as long as the polarizing film can be brought into a desired alignment state. Examples of a method for providing an alignment layer with an alignment state include: brushing and grinding the surface, oblique vapor deposition of inorganic compounds, forming a layer with micro grooves, and the like. Further, a method of forming a photoalignment layer that imparts an alignment function to molecular alignment by irradiation with polarized light is also preferable.

Hereinafter, 2 examples of the brushing treatment of the alignment layer and the photo-alignment layer will be described.

Brushing and grinding the alignment layer

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

First, a coating liquid for brushing the alignment layer containing the polymer material is coated on a substrate film, and then, the substrate film is subjected to heat drying or the like to obtain an alignment layer before brushing. The coating liquid for the alignment layer may have a crosslinking agent. Examples of the crosslinking agent include compounds containing a plurality of isocyanate groups, epoxy groups, oxazoline groups, vinyl groups, acryl groups, carbodiimide groups, alkoxysilyl groups, and the like; amide resins such as melamine compounds; phenolic resins, and the like.

The solvent used for the coating liquid for the alignment layer to be treated by brushing is not limited as long as the polymer material is dissolved. Specific examples of the solvent include water; alcohol solvents such as methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, cellosolve, and the like; ester 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. These solvents may be used alone or in combination.

The concentration of the coating liquid for the alignment layer to be subjected to brushing treatment may be appropriately adjusted depending on the kind of polymer, the thickness of the alignment layer to be produced, and the like, and is preferably in the range of 0.2 to 20% by mass, more preferably 0.3 to 10% by mass, as expressed as the solid content concentration.

As a method of performing the coating, a coating method such as a gravure coating method, a die coating method, a bar coating method, and an applicator method can be used; printing methods such as flexographic method and the like.

The temperature of the heat drying depends also on the substrate film and, in the case of PET, is preferably in the range of 30 to 170 ℃, more preferably in the range of 50 to 150 ℃, still more preferably in the range of 70 to 130 ℃. If the drying temperature is too low, a longer drying time is required, and the productivity is sometimes poor. If the drying temperature is too high, the orientation state of the base film is affected, the retardation is reduced, or the thermal shrinkage of the base film is increased, so that the optical function according to the design cannot be achieved, and the flatness is deteriorated. The heating and drying time is usually 0.5 to 30 minutes, preferably 1 to 20 minutes, more preferably 2 to 10 minutes.

The thickness of the brush-treated alignment layer is preferably 0.01 to 10. Mu.m, more preferably 0.05 to 5. Mu.m, still more preferably 0.1 to 1. Mu.m.

The brushing treatment may be generally performed by rubbing the surface of the polymer layer with paper or cloth in a constant direction. Generally, the surface of the alignment film is brushed using a brush roll of a napped cloth of fibers such as nylon, polyester, and acrylic.

In order to provide a polarizing film having a transmission axis in a predetermined direction with respect to the longitudinal direction of the long-sized base film, the rubbing direction of the alignment layer also needs to be formed at an angle corresponding thereto. The angle can be adjusted by adjusting the angle between the brush roller and the base film, the conveying speed of the base film, the rotational speed of the roller, and the like.

The substrate film may be directly subjected to a brushing treatment so that the surface of the substrate film has an alignment layer function. The above-mentioned cases are also included in the scope of the present invention.

Photo-alignment layer

The photo-alignment layer is an alignment film obtained by applying a coating liquid containing a polymer or monomer having a photoreactive group or a solvent to a base film, and applying polarized light, preferably polarized ultraviolet light, to the base film. The photoreactive group refers to a group that generates liquid crystal aligning ability by light irradiation. Specifically, the orientation of molecules generated by irradiation with light induces a photoreaction, such as an isomerization reaction, a dimerization reaction, a photocrosslinking reaction, or a photodecomposition reaction, which is the origin of the liquid crystal orientation ability. Among the photoreactive groups, those causing dimerization reaction or photocrosslinking reaction are preferable in terms of maintaining the smectic liquid crystal state of the polarizing film excellent in orientation. As the above photoreactive group capable of generating a reaction, an unsaturated bond is preferable, a double bond is particularly preferable, and a group having at least one selected from the group consisting of a c=c bond, a c=n bond, an n=n bond, and a c=o bond is particularly preferable.

Examples of the photoreactive group having a c=c bond include a vinyl group, a polyalkenyl group, a stilbene azole salt (stillbazolium) group, a chalcone group, and a cinnamoyl group. Examples of the photoreactive group having a c=n bond include groups having a structure such as an aromatic SchiFF base and an aromatic hydrazone. Examples of the photoreactive group having an n=n bond include those having an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a disazo group, a formazan (formazan) group, an oxazobenzene (azoxybenzene) group, and the like as basic structures. Examples of the photoreactive group having a c=o bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, and haloalkyl.

Among them, a photoreactive group capable of causing a photodimerization reaction is preferable, and a cinnamoyl group and a chalcone group are preferable because a photoalignment layer having a small amount of polarized light irradiation required for photoalignment and excellent thermal stability or temporal stability can be easily obtained. Further, as the polymer having a photoreactive group, those having a cinnamoyl group such as a cinnamic acid structure at the terminal of the side chain of the polymer are particularly preferable. Examples of the structure of the main chain include polyimide, polyamide, (meth) acrylic, polyester, and the like.

Specific examples of the alignment layer include: an alignment layer described in 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, japanese patent application laid-open No. 2007-121721, japanese patent application laid-open No. 2007-140465, japanese patent application laid-open No. 2007-156439, japanese patent application laid-open No. 2007-133184, japanese patent application laid-open No. 2009-109831, japanese patent application laid-open No. 2002-229039, japanese patent application laid-open No. 2002-265541, japanese patent application laid-open No. 2002-317013, japanese patent application laid-open No. 2003-520878, japanese patent application laid-open No. 2004-529320, japanese patent application laid-open No. 2013-33248, japanese patent application laid-open No. 2015-7702, japanese patent application laid-open No. 2015-129210, and the like.

The solvent of the coating liquid for forming a photo-alignment layer may be any solvent that can dissolve a polymer having a photoreactive group and a monomer. As specific examples of the solvent, those listed in the brushing treatment of the alignment layer can be exemplified. To the coating liquid for forming the photo-alignment layer, a photopolymerization initiator, a polymerization inhibitor, various stabilizers, and the like may be added as necessary. In addition, a polymer having a photoreactive group, a polymer other than a monomer, a monomer having no photoreactive group copolymerizable with the monomer having a photoreactive group, or the like may be added to the coating liquid for forming a photoalignment layer.

The concentration of the coating liquid for forming the photo-alignment layer, the coating method, the drying conditions, and the like can be exemplified as those listed for the brushing treatment of the alignment layer. The thickness of the photo-alignment layer is also the same as the preferred thickness of the brush-treated alignment layer.

By irradiating the photo-alignment layer before alignment thus obtained with polarized light in a predetermined direction with respect to the longitudinal direction of the base film, a photo-alignment layer in which the direction of the alignment regulating force is in a predetermined direction with respect to the longitudinal direction of the long base film can be obtained.

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

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

Examples of the light source of the polarized light include ultraviolet light lasers such as xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, krF, arF, etc., and high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are preferable.

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 polarizing plate, the direction of polarized light can be adjusted. The polarizing plate may be a polarizing filter; polarizing prisms such as Glan-Thompson, glan-Taylor; wire grid type polarizer. The polarized light is preferably substantially parallel light.

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

The irradiation intensity varies depending on the kind or amount of the polymerization initiator or the resin (monomer), and is preferably 10 to 10000mJ/cm based on 365nm ² More preferably 20 to 5000mJ/cm ² 。

(angle of transmission axis of polarizer and fast axis of substrate film)

The transmission axis of the polarizer is preferably substantially parallel to the fast axis of the substrate film. The term "substantially parallel" as used herein means that the transmission axis of the polarizer and the fast axis of the substrate film form an angle of 10 degrees or less. The angle between the transmission axis of the polarizing plate and the fast axis of the base film is preferably 7 degrees or less, more preferably 5 degrees or less. If the angle between the transmission axis of the polarizing plate and the fast axis of the base film exceeds 10 degrees, rainbow spots are likely to be visible when viewed from an oblique direction.

In the case of a polarizing plate obtained by stretching polyvinyl alcohol, the polarizing plate is usually stretched in the longitudinal direction, and the light transmission axis direction is orthogonal to the longitudinal direction. Therefore, a substrate film having a slow axis in the longitudinal direction (in the case of polyester, a main orientation axis in the longitudinal direction) is a suitable combination in terms of productivity. On the other hand, in the case of a polarizing plate obtained by aligning a polymerized liquid crystal compound, the light transmission axis direction of the polarizing plate can be adjusted in the brushing direction or the polarization direction of ultraviolet rays, and therefore, a combination is suitable in which the substrate film has a slow axis in either the longitudinal direction or the orthogonal direction.

A protective coating may be provided on the opposite side of the polarizing plate from the base film in order to prevent scratches from being applied in the subsequent step, and to prevent deterioration of the polarizing plate due to an adhesive or an adhesive, a coating solvent for a retardation layer, or the like. The protective coating layer may be suitably selected from PVA, other resins, ultraviolet curable resins, and the like within a range that does not adversely affect the polarizing plate. The thickness of the protective coating layer is preferably 0.01 to 10. Mu.m, more preferably 0.1 to 5. Mu.m.

3. Phase difference layer

In the circularly polarizing plate used in the present invention, a retardation layer is present on the side of the polarizing plate opposite to the surface of the base film. That is, the circularly polarizing plate has a retardation layer on the Electroluminescent (EL) element side of the polarizing plate. The EL display device of the present invention is characterized in that no independent film exists between the polarizer and the retardation layer, or in that only 1 independent film exists (here, the retardation layer itself is also included between the polarizer and the retardation layer). The free-standing film herein means a form in which the film exists independently in the process.

The term "retardation layer" as used herein means a layer having a function as a circularly polarizing plate, specifically, a 1/4 wavelength layer, a 1/2 wavelength layer, a C plate layer, and the like.

The absence of a free-standing film between the polarizer and the retardation layer means a case where the retardation layer is directly laminated on the polarizer instead of the free-standing film. The term "directly" as used herein refers to a case where there is no layer between the polarizing plate and the retardation layer, or between the retardation layers, or there is only an adhesive layer or an adhesive layer if any.

In the case where 1 independent film exists between the polarizer and the retardation layer, it means that only 1 of the polarizer protective film and the entire retardation layer is an independent film.

The 1/4 wavelength layer can be obtained by sticking a retardation film (self-standing film) having a coating type 1/4 wavelength layer (described later) prepared separately on an oriented film (self-standing film) such as polycarbonate or cycloolefin or a triacetyl cellulose (TAC) film. However, in terms of thinning or securing flexibility, it is preferable to provide a coating type 1/4 wavelength layer directly on the polarizing plate.

The coated 1/4 wavelength layer means that the 1/4 wavelength layer itself is formed by coating, and is not in a state of being independent. As a method of providing the 1/4 wavelength layer, the following method can be mentioned: a method of coating a polarizing plate with a retardation compound; and a method in which a 1/4 wavelength layer is provided on a substrate having releasability and transferred to a polarizing plate. As the 1/4 wavelength layer, a layer formed of a liquid crystal compound is preferable. Examples of the liquid crystal compound include rod-like liquid crystal compounds, polymer-like liquid crystal compounds, liquid crystal compounds having reactive functional groups, and the like. As a method of applying a retardation compound to a polarizing plate, it is preferable to apply a liquid crystal compound after subjecting the polarizing plate to a brushing treatment or providing the polarizing plate with the above alignment layer so as to have an alignment controlling force.

In the method of providing a coating type 1/4 wavelength layer on a releasable substrate and transferring it to a polarizing plate, it is preferable to brush-polish the releasable substrate or to apply a liquid crystal compound (1/4 wavelength layer) after providing the releasable substrate with the above alignment layer so as to have an alignment controlling force.

Further, as a method for performing transfer, the following method is also preferable: a substrate having releasability is coated with a birefringent resin, and stretched together with the substrate to form a 1/4 wavelength layer.

The thus obtained transfer-type 1/4 wavelength layer was adhered to a polarizing plate with an adhesive or an adhesive, and then the releasable substrate was peeled off. For the purpose of thickness reduction, it is preferable to adhere the sheet to the sheet with an adhesive, particularly an ultraviolet-curable adhesive.

In terms of the polarizer being less susceptible to the coating solvent of the 1/4 wavelength layer, the following method is preferable: a1/4 wavelength layer is additionally coated on the release substrate, and the coated layer is transferred onto the polarizer.

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

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, and the like can be used as reference for these methods and retardation layers.

When the 1/4 wavelength layer alone is used, the color may not be formed at 1/4 wavelength in a wide wavelength range of visible light. In this case, a 1/2 wavelength layer may be further provided. In the above case, it is preferable to provide a 1/2 wavelength layer between the polarizing plate and the 1/4 wavelength layer.

The preferable materials, morphology, manufacturing method, lamination method, and the like of the 1/2 wavelength layer are the same as those of the above-described 1/4 wavelength layer.

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

When only the 1/4 wavelength layer is used as the retardation layer, the angle between the orientation axis (slow axis) of the 1/4 wavelength layer and the transmission axis of the polarizing plate is preferably 35 to 55 degrees, more preferably 40 to 50 degrees, and even more preferably 42 to 48 degrees.

When the 1/4 wavelength layer and the 1/2 wavelength layer are used in combination as the retardation layer, 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, 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, more preferably in the range of 2θ+45 degrees±5 degrees, and still more preferably in the range of 2θ+45 degrees±3 degrees.

In the case of attaching the oriented film, these angles may be adjusted by the attaching angle, the stretching direction of the oriented film, and the like.

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

In the method of providing a coated 1/4 wavelength layer on a substrate and transferring the layer onto a polarizing plate, when the layer is attached to a roll, it is preferable to control the angle of brushing or the irradiation angle of polarized ultraviolet rays to a predetermined angle in advance.

In the case of using an oriented film or in the case of applying a birefringent resin to a base film and stretching the film together with the base film, it is preferable that the stretching be performed in an oblique direction so that a predetermined angle is formed when the film is attached to a roll.

Further, it is also preferable to provide a C plate layer on the 1/4 wavelength layer in order to reduce the change in coloring when viewed from an oblique direction. Among the C-plate layers, a positive or negative C-plate layer may be used according to 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 may be provided by directly coating a coating liquid to be the C plate layer on the 1/4 wavelength layer, or by transferring a C plate layer separately produced.

As these lamination methods, various methods can be employed. For example, the following methods are mentioned.

A method of disposing a 1/2 wavelength layer on a polarizing plate by transfer printing, and further disposing a 1/4 wavelength layer thereon by transfer printing.

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

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

A method of preparing a film-like 1/2 wavelength layer, applying or transferring the 1/4 wavelength layer thereon, and adhering the layer to a polarizing plate.

In addition, when the C-plate layers are laminated, various methods may be employed. For example, the following methods can be mentioned: a method of disposing a C plate layer by coating or transfer printing on a 1/4 wavelength layer disposed on a polarizing plate; and a method of laminating a C plate layer on a 1/4 wavelength layer to be transferred or pasted in advance.

In the present invention, in the case where a C plate layer is present between the polarizer and the 1/4 wavelength layer (including the 1/4 wavelength layer), the whole layer from the polarizer to the C plate layer (including the C plate layer) is preferably a coating layer. This means that no free-standing film is present on the opposite side of the polarizer from the substrate film. Specifically, it means that only any combination of an adhesive layer, a protective coating layer, an alignment layer, and a coated retardation layer is present on the side of the polarizing plate opposite to the base film. By forming such a structure, the circularly polarizing plate can be thinned or flexibility can be ensured.

Specific preferable examples of the lamination between the polarizer and the 1/4 wavelength layer include:

a polarizer/1/2 wavelength layer/adhesive layer/1/4 wavelength layer,

A polarizer/adhesive layer/1/2 wavelength layer/adhesive layer/1/4 wavelength layer,

Polarizer/protective coating layer/1/2 wavelength layer/adhesive layer/1/4 wavelength layer,

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

The intermediate 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, a rubber-based, acrylic, urethane-based, olefin-based, silicone-based, or like adhesive can be used without limitation. Among them, acrylic adhesives are preferable. The adhesive may be applied to the polarizing plate surface of an object such as a polarizing plate. The following method is preferred: the release film of one side of the transparent adhesive (release film/adhesive layer/release film) for optical use without a base material is peeled off and then stuck to the polarizer surface, thereby providing an adhesive layer. As the adhesive, ultraviolet curable, urethane-based and epoxy-based adhesives are preferably used.

The adhesive layer or the adhesive layer is used for attaching a polarizing plate, a protective coating layer, a coated retardation layer, or an EL element.

In the above, examples of the retardation layers (1/4 wavelength layer and 1/2 wavelength layer) include the following: the retardation layer (1/4 wavelength layer and 1/2 wavelength layer) may be provided on the object in advance, and the laminate of the base film and the polarizing plate may be adhered thereto. The same applies to the case where the C plate layer is provided.

The thickness of the circularly polarizing plate thus obtained is preferably 100 μm or less, more preferably 80 μm or less, still more preferably 70 μm or less, particularly preferably 60 μm or less.

Further, a circularly polarized light reflecting layer formed of a liquid crystal compound may be provided on the phase difference layer (the surface opposite to the polarizing plate) of the circularly polarized light plate. The circularly polarized light reflecting layer is preferably a cholesteric liquid crystal layer. The cholesteric liquid crystal layer may be 1 layer, but since the cholesteric liquid crystal layer has wavelength selectivity in reflection characteristics, it is preferable to provide a plurality of cholesteric liquid crystal layers to form uniform reflection characteristics in a wide region of visible light. The cholesteric liquid crystal layer is more preferably 2 or more layers, still more preferably 3 or more layers. The cholesteric liquid crystal layer is preferably 7 layers or less, more preferably 6 layers or less, particularly preferably 5 layers or less.

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

As the liquid crystal compound used for the circularly polarized light reflecting layer, the liquid crystal compound used for the polarizing film or the retardation layer can be mentioned.

Further, in order to orient the cholesteric liquid crystal in the circularly polarized light reflecting layer, it is preferable that the coating material for the circularly polarized light reflecting layer contains a chiral agent. By containing the chiral agent, a helical structure of the cholesteric liquid crystal phase is induced, and the cholesteric liquid crystal phase is easily obtained.

The chiral agent is not particularly limited, and a known chiral agent can be used. Examples of chiral agents include chiral agents for liquid crystal device manuals, chapter 3, chapter 4-3, TN (Twisted Nematic), STN (Super-twisted nematic display), compounds described in Japanese society of academy of sciences, code 142, 1989, isosorbide, and isomannide derivatives. The chiral agent preferably has a polymerizable group. The amount of the chiral agent to be blended is preferably 1 to 10 parts by mass based on 100 parts by mass of the liquid crystal compound.

In the case where the circularly polarized light reflecting layer is provided on the retardation layer by coating, it may be directly coated on the retardation layer, or an alignment layer may be provided and coated thereon. In the case of providing the circularly polarized light reflecting layer by transfer, it is possible to directly coat on the releasable substrate, or to provide an orientation layer on the releasable substrate and coat the circularly polarized light reflecting layer with a coating material thereon. The circularly polarized light reflecting layer and the retardation layer may be sequentially provided on the releasable substrate, and transferred to the polarizing plate. A part of the circularly polarized light reflecting layer and a part of the retardation layer may be sequentially provided on the releasable substrate, and the other part of the retardation layer may be provided on the separate polarizing plate, and transferred onto the retardation layer. The alignment layer is preferably the alignment layer described above.

The circularly polarized light reflecting layer is described in, for example, JP-A-1-133003, JP-A-3416302, JP-A-3363565, JP-A-8-271731, international publication No. 2016/194497, JP-A-2018-10086, etc., and these are incorporated by reference.

The thickness of the circularly polarized light reflecting layer is preferably 2.0 to 150 μm, more preferably 5.0 to 100 μm. In the case where the circularly polarized light reflecting layer is a plurality of layers, the total thickness is preferably in the above range.

By combining the circularly polarized light reflecting layer with the circularly polarized light plate, the decrease in brightness when the circularly polarized light plate for antireflection is provided in the EL display device can be reduced. Further, by providing the polarizing plate, the retardation layer, and the circularly polarized light reflecting layer by coating or transfer, the circularly polarizing plate can be thinned by forming a structure in which no self-standing film is provided between the polarizing plate and the circularly polarized light reflecting layer (including the polarizing plate itself and the circularly polarized light reflecting layer), and thus, it is easy to cope with thinning of the EL display device. In addition, such a structure is preferable as a flexible EL display device such as a foldable and rollable EL display device.

EL element

The EL display device of the present invention includes the circularly polarizing plate on the visible side of the EL element. The EL element is not limited to a known one, and among them, an organic EL element is preferable in terms of being thin. The EL element and the circularly polarizing plate are preferably bonded with an adhesive.

The EL display device of the present invention uses a circularly polarizing plate which uses a base film having a refractive index Ny in the fast axis direction of 1.568 to 1.63 of the base film, and has a number of independent films existing between a polarizing plate and a retardation layer of 1 sheet or less, and the light transmission axis of the polarizing plate is substantially parallel to the fast axis of the base film, so that the visibility is excellent (suppression of rainbow unevenness) and the thickness can be reduced, and trouble is not easily caused in the manufacturing process. The organic EL display device is particularly suitable for large EL display devices of 40 types (the length of the diagonal line of the display portion is 40 inches) or more, and further 50 types (the length of the diagonal line of the display portion is 50 inches) or more.

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

The flexible EL display device is preferably used for an EL display device which can be folded in a V-shape, a Z-shape, a W-shape, a double door shape, or the like when carried (folding EL display device) or an EL display device which can be wound in a roll shape (winding EL display device).

In the case where the display portion is provided on the folded inner surface side of the folded EL display device, the bending radius of the circularly polarizing plate in the folded state is reduced. In the case of such an EL display device, the main orientation direction of the base film is arranged in a direction perpendicular to the folding direction (direction of folding operation), so that occurrence of creases due to repeated folding operations can be effectively reduced. In the vertical direction, the angle between the main orientation direction and the folding direction of the base film 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 the crease can be reduced is considered that the substrate film is stretched by the repeated folding operation or the direction in which the substrate film is stretched is perpendicular to the main orientation direction of the molecules, and therefore the substrate film is easily stretched. The flexible EL display device of the present invention can be suitably used for a folding EL display device having a bending radius of 5mm or less, further 4mm or less, and particularly 3 mm.

In the case where the display portion is provided on the folded outer surface side of the device, the bending radius does not decrease even when the display portion is provided on the inner surface, or the case of the roll-up type EL display device, the main orientation direction of the base film may be used without particular limitation. 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 the EL display device in parallel, the flatness of the entire EL display device tends to be improved when the EL display device is expanded. In this case, the angle between the main orientation direction and the folding direction of the base film 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 is not peeled off even when repeatedly bent or placed in a high temperature state, is not easy to impart crease, and has excellent visibility. Further, when a polyester film is used as a base film of a circularly polarizing plate, an EL display device having a circularly polarizing plate excellent in moisture permeation resistance, dimensional stability, mechanical strength and chemical stability can be provided.

Examples

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples. And can be modified and implemented as appropriate within the scope of the gist of the present invention, and all of them are included in the scope of the present invention.

The evaluation methods of physical properties in examples are as follows.

(1) Evaluation of the slow and fast axes directions of the film

The evaluation of the film in the axial direction was measured by a molecular orientation meter (model MOA-6004, manufactured by Oji Scientific Instruments Co ltd.).

(2) ΔNxy and delay amount (Re)

The retardation is a parameter defined by the product (Δnxy×d) of the refractive index anisotropy (Δnxy= |nx-ny|) of orthogonal biaxial on the film and the film thickness d (nm), and represents the optical isotropy and anisotropy. The anisotropy of refractive index (Δnxy) of biaxial was determined by the following method. The slow axis direction of the film was determined by a molecular orientation meter (model MOA-6004, manufactured by Oji Scientific Instruments Co Ltd.) and cut into a rectangle of 4 cm. Times.2 cm so that the slow axis direction was parallel to the long side of the sample for measurement, and the sample for measurement was obtained. For this sample, the refractive index of the orthogonal biaxial (refractive index in the slow axis direction: nx, refractive index in the direction orthogonal to the slow axis direction in the plane (i.e., refractive index in the fast axis direction): ny) and refractive index in the thickness direction (nz) were measured by an Abbe refractometer (ATAGO CO., LTD. Co., NAR-4T, measurement wavelength 589 nm), and the absolute value of the difference between the refractive indices of the biaxial (|nx-ny|) was used as the anisotropy of the refractive index (. DELTA.Nxy). The thickness D (nm) of the film was measured by an electronic micrometer (Fine Ryuf co., ltd., millitron 1245D), and the unit was converted to nm. The retardation (Re) was obtained from the product (DeltaNxy×d) of the anisotropy of refractive index (DeltaNxy) and the thickness d (nm) of the film.

(3) Nz coefficient

The values of nx, ny and Nz measured by Abbe refractometer in the above (2) are substituted into |nx-nz|/|nx-ny| to obtain the Nz coefficient.

(4) Rainbow spot observation

The polarizing plate obtained below was placed in an organic EL display so that the PET film was on the visible side instead of the circularly polarizing plate (circularly polarizing plate placed on the visible side of the organic EL element) of a commercially available organic EL display (organic EL television C6P 55 inches manufactured by LG corporation). The presence or absence of occurrence of rainbow unevenness was visually observed from the front side and the oblique direction of the organic EL display, and the presence or absence of occurrence of rainbow unevenness was determined as follows.

O: no iridescence was observed when observed from any direction.

Delta: when viewed from an oblique direction of 60 degrees or more with respect to the normal direction, a shallow rainbow spot can be observed.

X: rainbow spots can be observed when viewed from an oblique direction of 60 degrees or more with respect to the normal direction.

(5) Thickness of base film and circular polarizing plate

The thicknesses of the substrate film and the circularly polarizing plate were measured by a commercially available digital thickness meter.

(6) Based on the thickness of the layers applied

The thicknesses of the layers based on the coating are as follows: under the same coating conditions, the obtained product was coated by embedding a PET film (PET which was subjected to an easy-to-adhere treatment as required) with an epoxy resin, cutting into slices, and observing with a microscope. The microscope is an optical microscope, a transmission electron microscope or a scanning electron microscope depending on the thickness.

(7) Operability of

The circular polarizing plate was cut to a value corresponding to A5, and a paper tube having an outer diameter of 6 inches was wound together with a biaxially oriented PET film having a thickness of 50 μm so that the longitudinal direction became the winding direction. The coiling is performed as follows: a circularly polarizing plate sample was inserted at the time of winding up the PET film 3m, and a 7m PET film was further wound up. In addition, as a blank, only a base film was wound. These were stored at 40℃for 3 days, allowed to return to room temperature, and then unwound, with the curled convex portion upward, placed on a glass plate, and the curled state was observed after 30 minutes. In addition, pressing from above, whether flattening is easy or not is attempted. The evaluation criteria are as follows.

And (3) the following materials: substantially the same as the blank and substantially no curl.

O: curl is slightly stronger than blank, but easily flattened.

Delta: the curl is strong compared to the blank, but can be flattened.

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

(8) Tear strength

The tear strength (N/mm) per film thickness was measured for each film by the Autograph (AG-X plus) manufactured by Shimadzu corporation according to the Right-angle tear method (JIS K-7128-3). The tear strength was measured in 2 directions (i.e., 2 directions of the slow axis direction and the fast axis direction) parallel and perpendicular to the direction of the main axis of orientation (slow axis) of the film, and the smaller number was recorded as the tear strength in table 1. The alignment major axis direction (slow axis direction) was measured by a molecular alignment meter (model MOA-6004 molecular alignment meter manufactured by Oji Scientific Instruments Co ltd.

(9) r=3 bending resistance

A50 mm by 100mm circular polarizing plate sample was prepared, and the sample was bent 10 ten thousand times at a speed of 1 time/second with a bending radius of 3mm using an unloaded U-shaped expansion tester (DLDMLH-FS, manufactured by Yuasa System Co.). At this time, for the sample, the position of 10mm at both ends of the long side was fixed, the bent portion was set to 50mm×80mm, the inside of the bend was set to the substrate film side, and the slow axis of the substrate film was set to be orthogonal to the bending direction. After the bending process was completed, the sample was placed on a flat surface with the inside of the bend downward, and visual inspection was performed. The evaluation criteria are as follows.

And (3) the following materials: deformation of the sample cannot be confirmed.

O: there was deformation of the sample, but the maximum height of the float was below 5mm when placed horizontally.

X: the maximum height of the floating of the sample is more than 5mm when the sample is creased or horizontally placed.

(10) r=5 bending resistance

The bending resistance test was performed in the same manner as in r=3 except that the bending radius was set to 5mm, the outside of the bending was the substrate film side, and the slow axis of the substrate film was parallel to the bending direction.

(11) Resistance to thermal bending

The substrate film surface was set to the inner side, and a sample having a size of 50mm×100mm was bent 180 degrees in the longitudinal direction so that the bending radius became 3mm, and the sample was fixed with a jig and left at a temperature of 60℃and RH65% for 3 hours. Then, the fixture was removed at room temperature, and the state was observed after 1 hour. The slow axis of the base film is perpendicular to the bending direction. The evaluation criteria are as follows.

And (3) the following materials: substantially return to the plane

O: in a slightly bent state (less than 20 DEG)

X: becomes a bent state (more than 20 DEG)

< preparation of easily adhesive layer component >

(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, 14.8 parts by mass of dimethyl isophthalate 5-sodium sulfonate, 233.5 parts by mass of diethylene glycol, 136.6 parts by mass of ethylene glycol and 0.2 part by mass of tetra-n-butyl titanate were charged, and transesterification was carried out at a temperature of 160℃to 220℃for 4 hours. Then, the mixture was heated to 255℃and the reaction system was slowly depressurized, followed by reaction under a reduced pressure of 30Pa for 1 hour and 30 minutes to obtain a copolyester resin. The obtained copolyester resin is light yellow and transparent. The reduced viscosity of the copolyester resin was measured and found to be 0.70dl/g. The reduced viscosity was obtained as follows: for 0.1g of the resin, 25mL of a mixed solvent of phenol (60 mass%) and 1, 2-tetrachloroethane (40 mass%) was used as a solvent, and the value was measured at 30 ℃. The glass transition temperature based on DSC was 40 ℃.

(preparation of aqueous polyester dispersion)

In a reactor equipped with a stirrer, a thermometer and a reflux apparatus, 30 parts by mass of a polyester resin and 15 parts by mass of ethylene glycol n-butyl ether were placed, and the mixture was stirred while being heated at 110 ℃. 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 polyester aqueous dispersion having a solid content of 30 mass%.

(preparation of aqueous polyvinyl alcohol solution)

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

(polymerization of blocked polyisocyanate crosslinking agent used in easy-to-bond layer P1)

100 parts by mass of an isocyanurate-structured polyisocyanate compound (produced by Duranate TPA, asahi Kasei Chemicals Corporation), 55 parts by mass of propylene glycol monomethyl ether acetate, and 30 parts by mass of polyethylene glycol monomethyl ether (average molecular weight 750) were charged into a flask equipped with a stirrer, a thermometer, and a reflux condenser, and the flask was kept at 70℃for 4 hours under a nitrogen atmosphere. After that, the temperature of the reaction solution was lowered to 50℃and 47 parts by mass of methyl ethyl ketoxime was added dropwise. The infrared spectrum of the reaction solution was measured, and it was confirmed that the absorption of isocyanate groups had disappeared, to obtain an aqueous dispersion of blocked polyisocyanate having a solid content of 75% by mass.

(preparation of coating liquid for easy-to-bond layer P1)

The following raw materials were mixed to prepare a coating liquid.

(polymerization of urethane resin used in the easy-to-bond layer P2)

A urethane resin containing an aliphatic polycarbonate polyol as a constituent was produced as follows. 43.75 parts by mass of 4, 4-diphenylmethane diisocyanate and dimethylol were charged into a four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube and a thermometer12.85 parts by mass of hydroxybutyric acid, 153.41 parts by mass of polyhexamethylene carbonate diol having a number average molecular weight of 2000, 0.03 part by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent were stirred under a nitrogen atmosphere at 75℃for 3 hours, and it was confirmed that the reaction solution reached a predetermined amine equivalent. Subsequently, the temperature of the reaction solution was lowered to 40 ℃, and then 8.77 parts by mass of triethylamine was added thereto to obtain a polyurethane prepolymer solution. Then, 450g of water was added to a reaction vessel equipped with a high-speed stirring homogenizer, and the temperature was adjusted to 25℃and the water was stirred for 2000 minutes ^-1 The polyurethane prepolymer solution was added and dispersed while stirring and mixing. Thereafter, a part of acetone and water was removed from the mixed solution under reduced pressure, thereby preparing a water-soluble polyurethane resin having a solid content of 35%. The glass transition point temperature of the polyurethane resin obtained, which contains the aliphatic polycarbonate polyol as a constituent, was-30 ℃.

(polymerization of oxazoline-based crosslinking agent used in the easy-to-bond layer P2)

A flask equipped with a thermometer, a nitrogen inlet pipe, a reflux condenser, a dropping funnel, and a stirrer was charged with a mixture of 58 parts by mass of ion-exchanged water and 58 parts by mass of isopropyl alcohol as an aqueous medium, and 4 parts by mass of a polymerization initiator (2, 2' -azobis (2-amidinopropane) dihydrochloride). On the other hand, a mixture of 16 parts by mass of 2-isopropenyl-2-oxazoline, which is a polymerizable unsaturated monomer having an oxazoline group, 32 parts by mass of methoxypolyethylene glycol acrylate (average addition mole number of ethylene glycol: 9 moles, manufactured by Xinzhou chemical Co., ltd.), and 32 parts by mass of methyl methacrylate was charged into a dropping funnel, and was added dropwise at 70℃for 1 hour under a nitrogen atmosphere. After the completion of the dropwise addition, the reaction solution was stirred for 9 hours and cooled, whereby a water-soluble resin having an oxazoline group and a solid content concentration of 40 mass% was obtained.

(preparation of coating liquid for easy-to-bond layer P2)

The following raw materials were mixed to prepare a coating liquid for forming a coating layer excellent in adhesion to a functional layer.

< production of polyester resin for substrate film >

PREPARATION EXAMPLE 1-polyester X

The esterification reactor was heated, and 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged at a temperature of 200℃while stirring, and 0.017 parts by mass of antimony trioxide, 0.064 parts by mass of magnesium acetate tetrahydrate, and 0.16 parts by mass of triethylamine were charged as catalysts. Then, the temperature was raised under pressure, the esterification reaction was carried out under pressure at 0.34MPa and 240℃and the pressure was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Further, the temperature was raised to 260℃over 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added thereto. Then, after 15 minutes, the resultant esterification reaction product was transferred to a polycondensation reaction vessel, and after 15 minutes, the polycondensation reaction was carried out at 280℃under reduced pressure.

After the completion of the polycondensation reaction, the mixture was filtered through a 95% cut-off filter made of Naston having a diameter of 5. Mu.m, extruded from a nozzle in the form of strands, cooled and solidified with cooling water previously subjected to filtration (pore diameter: 1 μm or less), and cut into pellets. The obtained polyethylene terephthalate resin (X) had an intrinsic viscosity (intrinsic viscosity) of 0.73dL/g and was substantially free of inactive particles and internal precipitated particles (hereinafter, the polyethylene terephthalate resin (X) was abbreviated as PET (X)).

PREPARATION 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) were mixed and kneaded with a kneading extruder to obtain an ultraviolet absorber-containing polyethylene terephthalate resin (Y) (hereinafter, the polyethylene terephthalate resin (Y) was abbreviated as PET (Y))

(production of substrate film 1)

90 parts by mass of PET (X) resin pellets containing no particles and 10 parts by mass of PET (Y) resin pellets containing an ultraviolet absorber were dried at 135℃under reduced pressure (1 Torr) for 6 hours as raw materials for an intermediate layer of a base film, and then fed to an extruder 2 (for an intermediate layer II), and PET (X) was dried by a conventional method, and fed to an extruder 1 (for an outer layer I layer and an outer layer III layer) respectively, and dissolved at 285 ℃. The 2 polymers were each filtered with a filter medium (nominal filtration accuracy 10 μm particles 95% cut off) of a stainless steel sintered body, laminated in 2 kinds of 3-layer joint blocks, extruded from a pipe head in a sheet form, and then cast by electrostatic casting, wound around a casting drum having a surface temperature of 30℃and cooled and solidified to prepare an unstretched film. At this time, the discharge amount of each extruder was adjusted so that the ratio of thicknesses of the I layer, the II layer, and the III layer became 10:80:10.

Next, a P1 coating solution was applied to one side and a P2 coating solution was applied to the opposite side of the unstretched PET film by a reverse roll method so that the coating amounts after drying became 0.12g/m ² After that, the mixture was introduced into a dryer and dried at 80℃for 20 seconds.

The unstretched film having the coating layer formed thereon was introduced into a simultaneous biaxial stretching machine, and the end of the film was introduced into a hot air zone at 125℃with a jig fixed, and stretched 6.5 times in the advancing direction and 2.2 times in the widthwise direction. Next, the biaxially oriented PET film was subjected to a treatment at 225℃for 30 seconds while maintaining the width stretched in the width direction, to obtain a film thickness of 35. Mu.m. The film is wound into a roll form to form a film roll. The slow axis of the obtained film deviates from the travelling direction by within 3 degrees.

(production of substrate film 2)

The thickness of the unstretched film was changed, and the biaxially oriented PET film having a film thickness of 50 μm was obtained by stretching in the advancing direction and the width direction by the same method as the above-mentioned method for producing the base film 1. The film is wound into a roll form to form a film roll. The slow axis of the obtained film deviates from the travelling direction by within 3 degrees.

(production of substrate film 3)

The thickness of the unstretched film was changed, and the biaxially oriented PET film having a film thickness of 80 μm was obtained by stretching in the advancing direction and the width direction by the same method as the above-mentioned method for producing the base film 1. The film is wound into a roll form to form a film roll. The slow axis of the obtained film deviates from the travelling direction by within 3 degrees.

(production of substrate film 4)

The thickness of the unstretched film was changed, and the biaxially oriented PET film having a film thickness of 35 μm was obtained by stretching 2.2 times in the advancing direction and 6.0 times in the widthwise direction by the same method as the above-mentioned method for producing the base film 1. The film is wound into a roll form to form a film roll. The slow axis of the obtained film deviates from the travelling direction by within 5 degrees.

(production of substrate film 5)

An unstretched film was produced in the same manner as in the production method of the base film 1, and was stretched 6.5 times in the row direction on a roll set having a peripheral speed difference by a sequential biaxial stretching machine, and then stretched 2.2 times in the width direction in a tenter to obtain a biaxially oriented PET film having a film thickness of 35. Mu.m. The film is wound into a roll form to form a film roll. The slow axis of the obtained film deviates from the travelling direction by within 5 degrees.

(production of substrate film 6)

Except for changing the thickness, an unstretched film was produced in the same manner as in the above-mentioned method for producing a base film 1, and stretched 3.6 times in the width direction in a tenter to obtain a biaxially oriented PET film having a film thickness of 35. Mu.m. The film is wound into a roll form to form a film roll. The slow axis of the obtained film deviates from the travelling direction by within 5 degrees.

(production of base film 7)

An unstretched film was produced in the same manner as in the production method of the base film 1 except that the thickness was changed, and the film was stretched 3.8 times in the row direction on a roll set having a peripheral speed difference by a sequential biaxial stretching machine, and then, the film was heat-set in the width direction without stretching in a tenter, to obtain a biaxially oriented PET film having a film thickness of 35 μm. The film is wound into a roll form to form a film roll. The slow axis of the obtained film deviates from the travelling direction by within 5 degrees.

(production of substrate film 8)

The thickness of the unstretched film was changed, and the biaxially oriented PET film having a film thickness of 35 μm was obtained by stretching 4.5 times in the advancing direction and 2.5 times in the width direction by the same method as the above-mentioned method for producing the base film 1. The film is wound into a roll form to form a film roll. The slow axis of the obtained film deviates from the travelling direction by within 5 degrees.

The properties of the obtained base material films 1 to 8 are shown in table 1.

TABLE 1

(lamination of hard coat layers)

A coating solution having a concentration of 40% was prepared by mixing 95 parts by mass of a urethane acrylate hard coating agent (BEAMSET (registered trademark) 577, 100% by solid content, manufactured by Kbac chemical industry Co., ltd.), 5 parts by mass of a photopolymerization initiator (Irgacure (registered trademark) 184, 100% by solid content, manufactured by BASF Japan Co., ltd.) and 0.1 part by mass of a leveling agent (BYK 307, 100% by solid content, manufactured by BYK Japan Co., ltd.) and diluting the mixture with a solvent having toluene/MEK=1/1.

A Meyer rod was used to apply a hard coat coating solution to the pressure-sensitive adhesive layer P2 of the base film so that the film thickness after drying became 5.0. Mu.m, and after drying at 80℃for 1 minute, ultraviolet rays were irradiated (cumulative light amount 200 mJ/cm) ² )。

(lamination of polarizing plates)

As a method of providing a polarizing plate on a base film, the following 4 methods were performed.

(A) A method of providing a brush-polished alignment layer on a base film and providing a polarizing film formed of a liquid crystal compound and a dichroic dye thereon (polarizing plate lamination method A)

(B) A method of providing a base film with a photo-alignment layer thereon and providing a polarizing film formed of a liquid crystal compound and a dichroic dye thereon (polarizing plate laminating method B)

(C) A method of providing a polarizing film formed of PVA/iodine on a thermoplastic substrate and then transferring the polarizing film to a substrate film (polarizing plate laminating method C)

(D) A method of forming a polarizing film composed of PVA/iodine and adhering the polarizing film to a base film (polarizing plate laminating method D)

Details of each method are described below.

Polarizing plate laminating method A

(formation of brush orientation layer)

A coating material for brushing the alignment layer having the following composition was applied to the easy-to-adhere layer P1 of the base film by a bar coater, and dried at 120℃for 3 minutes to form a film having a thickness of 200 nm. Then, the surface of the obtained film was treated with a brush roll around which a nylon-made rag was wound, to obtain a base film having a brush alignment layer laminated thereon. The brushing direction was set to 0 degrees or 90 degrees with respect to the longitudinal direction of the film.

Paint for brushing alignment layer

Completely saponified polyvinyl alcohol molecular weight 800 mass parts

Ion exchange water 100 parts by mass

(Synthesis of polymerizable liquid Crystal Compound)

The compound (1) represented by the following formula (1) and the compound (2) represented by the following formula (2) were synthesized with reference to the description of paragraph [0134] of Japanese patent application laid-open No. 2007-510946 and Lub et al, recl, trav. Chim. Pays-Bas,115, 321-328 (1996).

Pigment (3) represented by the following formula (3) was synthesized with reference to example 1 of Japanese patent application laid-open No. 63-301850.

Pigment (4) represented by the following formula (4) was synthesized with reference to example 2 of Japanese patent publication No. 5-49710.

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

(formation of polarizing film)

A polarizing film coating material comprising 75 parts by mass of the compound (1), 25 parts by mass of the compound (2), 2.5 parts by mass of the dye (3), 2.5 parts by mass of the dye (4), 2.5 parts by mass of the dye (5), 6 parts by mass of Irgacure (registered trademark) 369E (manufactured by BASF corporation) and 250 parts by mass of o-xylene was applied to a base film laminated with a brush alignment layer by a bar coater, and dried at 110 ℃ for 3 minutes to form a film having a thickness of 2 μm. Subsequently, UV light is irradiated, and a polarizing plate is provided on the base film.

Polarizing plate laminating method B

(Synthesis of coating for photo-alignment layer)

Based on the descriptions of example 1, example 2 and example 3 of japanese patent application laid-open publication 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 by a bar coater, and dried at 80℃for 1 minute to form a film having a thickness of 150 nm. Subsequently, polarized light UV light was irradiated to obtain a base film having a photo-alignment layer laminated thereon.

The polarizing film is coated with the coating material on the photo-alignment layer, and the polarizing layer is provided on the substrate film on which the alignment layer is laminated in the same manner.

Polarizing plate laminating method C

(production of substrate-laminated polarizing plate)

An unstretched film having a thickness of 100 μm was produced using polyester X as a thermoplastic resin base material, and an aqueous solution of polyvinyl alcohol having a polymerization degree of 2400 and a saponification degree of 99.9 mol% was applied to one side of the unstretched film and dried to form a PVA layer.

The laminate obtained was stretched to 2 times in the longitudinal direction between rolls having different peripheral speeds at 120℃and wound up. Next, the obtained laminate was treated with a 4% aqueous boric acid solution for 30 seconds, then immersed in a mixed aqueous solution of iodine (0.2%) and potassium iodide (1%) for 60 seconds, and then treated with a mixed aqueous solution of potassium iodide (3%) and boric acid (3%) for 30 seconds.

Further, the laminate was uniaxially stretched in the longitudinal direction in a mixed aqueous solution of boric acid (4%) and potassium iodide (5%) at 72 ℃. The stretched laminate was then washed with a 4% aqueous potassium iodide solution, the aqueous solution was removed by an air knife, and then dried in an oven at 80℃to obtain a base material laminated polarizing plate 1 having a width of 30cm and a length of 1000m by slitting and winding both end portions. The total stretching ratio was 6.5 times, and the thickness of the polarizing plate was 5. Mu.m. The thickness is as follows: the base laminated polarizing plate 1 was embedded in an epoxy resin, cut into slices, and observed and read by an optical microscope.

(lamination of polarizing layers)

After the ultraviolet curable acrylic adhesive is applied to the base film, the polarizer surface of the base laminated polarizer 1 is stuck, ultraviolet light is irradiated from the base laminated polarizer 1 side, and the base laminated polarizer 1 is laminated on the base film. Thereafter, the thermoplastic resin substrate is peeled off, and a polarizing plate is provided on the substrate film.

Polarizing plate laminating method D

(production of Single-layer polarizing plate)

A polyvinyl alcohol resin film having a saponification degree of 99.9% was introduced into a roll having a peripheral speed difference, and uniaxially stretched at 100℃to 3 times. The stretched polyvinyl alcohol stretched film obtained 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% aqueous solution of boric acid at 72 ℃. Then, the polarizing plate was obtained by washing with ion-exchanged water, immersing in a 6% aqueous potassium iodide solution, removing the aqueous solution with an air knife, and drying at 45 ℃. The thickness of the polarizer was 18. Mu.m.

(lamination of polarizing plates)

After an ultraviolet-curable acrylic adhesive is applied to the base film, a single-layer polarizer is attached, ultraviolet light is irradiated from the side of the base film on which the polarizer is laminated, and the polarizer is provided on the base film.

(lamination of phase-difference layers)

As a method of providing a retardation layer on a polarizing plate, the following 4 methods were performed.

(F) Method of providing 1/2 wavelength layer and 1/4 wavelength layer on polarizing plate by coating (lamination method of retardation layer F)

(G) A method of transferring a 1/2 wavelength layer provided on a release film onto a polarizing plate and further transferring a 1/4 wavelength layer provided on the release film thereon (a method of laminating a retardation layer G)

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

(I) A method of providing 1/2 wavelength layers on 1/4 wavelength layers by coating and adhering these 1/2 wavelength layers to a polarizing plate (method of laminating retardation layers I)

Details of each method are described below.

Lamination method F of phase difference layer

A polyvinyl alcohol film having a thickness of about 100nm was obtained by applying a polyvinyl alcohol (a 2% by mass aqueous solution (0.2% of surfactant) of polyvinyl alcohol 1000 having a completely saponified form to a polarizer provided on a base film, and then subjecting the surface of the polyvinyl alcohol film to a brushing treatment, and the surface was subjected to a brushing treatment so that the angle of the brushing treatment became 15 degrees with respect to the absorption axis of the polarizer.

Next, a retardation layer forming solution having the following composition was applied to the surface subjected to the brushing treatment by a bar coating method. The coated film was dried, subjected to alignment treatment, and then irradiated with ultraviolet light to be cured, thereby producing a 1/2 wavelength layer.

Solution for forming retardation layer

LC242 (BASF Co., ltd.) 75 parts by mass

20 parts by mass of the following compound

5 parts by mass of trimethylolpropane triacrylate

Irgacure379 mass parts

0.1 part by mass of a surfactant

Methyl ethyl ketone 250 parts by mass

Next, a polyvinyl alcohol film was formed on the 1/2 wavelength layer in the same manner, and the resultant was subjected to a brushing treatment. The brushing treatment was performed so that the angle was 73 degrees with respect to the absorption axis of the polarizing plate. The retardation layer forming solution was applied by a bar coating method, dried, subjected to alignment treatment, and then irradiated with ultraviolet rays to be cured. In bar coating, the thickness was adjusted to be a 1/4 wavelength layer.

Method G for laminating retardation layer

A biaxially stretched polyethylene terephthalate (PET) film having a thickness of 50 μm was subjected to a brushing treatment. A retardation layer forming solution was applied to the brush-treated surface by a bar coating method, dried, subjected to an orientation treatment, and then irradiated with ultraviolet rays to cure the retardation layer forming solution, and a 1/2 wavelength layer was provided on the biaxially stretched polyethylene terephthalate film. Then, the 1/2 wavelength layer was adhered to the polarizer surface provided on the base film using an ultraviolet curable adhesive. After that, the biaxially stretched PET film was peeled off. The sticking was performed so as to be 15 degrees with respect to the absorption axis of the polarizing plate.

Similarly, a 1/4 wavelength layer was provided on a biaxially oriented PET film, and the 1/2 wavelength layer was adhered with an optically clear adhesive sheet. The sticking was performed so as to be 75 degrees with respect to the absorption axis of the polarizing plate.

Lamination method H of phase difference layer

A biaxially stretched polyethylene terephthalate (PET) film having a thickness of 50 μm was subjected to a brushing treatment. A retardation layer forming solution was applied to the brush-treated surface by a bar coating method, dried, subjected to an orientation treatment, and then irradiated with ultraviolet rays to cure the retardation layer forming solution, and a 1/4 wavelength layer was provided on the biaxially stretched polyethylene terephthalate film. A polyvinyl alcohol film having a thickness of about 100nm was obtained by applying a polyvinyl alcohol (a 2% by mass aqueous solution (0.2% of surfactant) to the 1/4 wavelength layer and drying the same, and then a polyvinyl alcohol film was subjected to a brushing treatment on the surface of the polyvinyl alcohol film, and a solution for forming a retardation layer was applied to the brushing treated surface of PVA by a bar coating method and dried, and then the film was subjected to an orientation treatment, and then irradiated with ultraviolet light to cure the film, thereby providing a 1/2 wavelength layer, and the film was subjected to a brushing direction at the time of providing a 1/4 wavelength layer and a brushing direction at the time of providing a 1/2 wavelength layer at an angle of 60 degrees, and then a biaxially stretched PET film was peeled off from the film by using an ultraviolet curable adhesive, and the film was subjected to a brushing direction of the polarizing film and a brushing direction of the 1/2 wavelength layer at the time of providing a 1/2 wavelength layer at an angle of 75 degrees.

Lamination method I of phase difference layer

The 1/4 wavelength film is unwound from a roll of 1/4 wavelength film having a slow axis in the length direction and cut to a desired length, and the surface is subjected to brushing treatment. A1/2 wavelength layer was provided on the surface to be treated by brushing in the same manner as in the lamination method F of the retardation layer. Further, a 1/2 wavelength layer was adhered to a polarizer provided on the base film using an ultraviolet curable adhesive. The 1/4 wavelength film was produced as follows: the propylene-ethylene random copolymer (ethylene content: 5%) was extruded into a sheet form, and was stretched by a roll in the longitudinal direction to produce a film (thickness: 20 μm). In the sticking, the absorption axis of the polarizer and the brushing direction of the 1/2 wavelength layer were set to 15 degrees, and the absorption axis of the polarizer and the slow axis direction of the 1/4 wavelength layer were set to 75 degrees.

The thickness of the retardation layer applied as described above was 1.2 μm in the 1/4 wavelength layer and 2.3 μm in the 1/2 wavelength layer. The thickness of the adhesive layer was 3. Mu.m.

Examples 1 to 23

A circularly polarizing plate was produced by providing a polarizing plate and a retardation layer on the base film shown in table 2 by the method shown in table 2.

Comparative example 1

A polarizing plate was produced by laminating a polarizing plate on a base film by the polarizing plate laminating method D, and then adhering a TAC film having a thickness of 80 μm to the polarizing plate with a PVA adhesive. Further, a retardation layer was provided on the TAC film of the polarizing plate by lamination method I of the retardation layer, to prepare a circularly polarizing plate.

Comparative example 2

After a polarizing plate was laminated on a base film by the polarizing plate laminating method a, a 1/2 wavelength film was laminated on the polarizing plate, and a 1/4 wavelength film was further laminated thereon. The 1/2 wavelength film was used such that the thickness of the 1/4 wavelength film was 2 times, and each lamination was performed according to the lamination method I of the retardation layer. The 1/2 wavelength plate was set to 15 degrees with respect to the absorption axis of the polarizer, and the 1/4 wavelength layer was set to 75 degrees with respect to the absorption axis of the polarizer.

Comparative examples 3 to 5

The properties of the circularly polarizing plates obtained in examples 1 to 23 and comparative examples 1 to 5 are shown in Table 2.

TABLE 2

The circularly polarizing plate thus obtained was stuck to an organic EL element via an adhesive layer having a thickness of 25. Mu.m, and a folding display of the smart phone type was produced which was foldable in two at the center of the whole having a radius of 3mm corresponding to the bending radius. The circularly polarizing plate is disposed on the surface of 1 display in succession by means of a folded portion, and the hard coat layer is disposed on the surface of the display, and is disposed so that the slow axis of the base film is orthogonal to the folding direction. The evaluation results of the circular polarizing plate used are shown in table 3.

TABLE 3

When the circularly polarizing plate of each embodiment is used, the circularly polarizing plate is folded into two in the central part, so that the portable smart phone is manufactured, the actions and the visibility are met, and no rainbow spots are observed.

(preparation of coating for circularly polarized light reflective layer)

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

LC242 (BASF Co., ltd.) 100 parts by mass

LC756 (BASF Co., ltd.) 5 parts by mass

Irgacure 819 4 parts by mass

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

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

(formation of circularly polarized light reflecting layer)

The circularly polarizing plate obtained in the example was coated with a coating material for a circularly polarizing reflecting layer on a retardation layer by a bar coater, and dried at 85 ℃. Subsequently, ultraviolet rays were irradiated into an oven at 85℃to provide a circularly polarized light reflecting layer.

(evaluation of circularly polarizing plate having circularly polarized light reflecting layer laminated thereon)

The circularly polarizing plate having the circularly polarizing reflecting layer obtained in the above was assembled in an EL display in the same manner and visually observed, and as a result, the effect of improving brightness was confirmed as compared with the circularly polarizing plate of each example having no circularly polarizing reflecting layer.

In addition, the operability and bending resistance were evaluated in the same manner, and the results were at the same level as those of the original examples.

The EL display device of the present invention uses a circularly polarizing plate which uses a base film having a refractive index ny in the fast axis direction of 1.568 to 1.63, and has a number of independent films existing between a polarizing plate and a retardation layer of 1 sheet or less, and the light transmission axis of the polarizing plate is substantially parallel to the fast axis of the base film, so that the visibility is excellent (suppression of rainbow unevenness) and the thickness can be reduced, and trouble is not easily caused in the manufacturing process.

In addition, the flexible EL display device is not peeled off even when repeatedly bent or placed in a high temperature state, and is not easy to be provided with creases, and has excellent visibility.

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

Claims

1. An electroluminescent display device, comprising: an electroluminescent element, and a circularly polarizing plate disposed on the visible side of the electroluminescent element,

the circular polarizing plate is provided with a phase difference layer, a polarizing plate and a base material film in sequence,

(2) The phase difference layer itself is also included between the polarizing plate and the phase difference layer, where no or only 1 self-standing film is present between the polarizing plate and the phase difference layer; and, a step of, in the first embodiment,

2. The electroluminescent display device according to claim 1, wherein the in-plane birefringence Δnxy of the base material film is 0.06 or more and 0.2 or less.

3. The electroluminescent display device according to claim 1 or 2, wherein the smaller of the tear strength in the slow axis direction and the fast axis direction of the base film by the right angle tearing method has a value of 250N/mm or more.

4. An electroluminescent display device according to any one of claims 1 to 3 wherein the thickness of the polarizer is 12 μm or less.

5. The electroluminescent display device according to any one of claims 1 to 4, wherein the polarizing plate is formed of a polymerizable liquid crystal compound and a dichroic dye.

6. The electroluminescent display device according to any one of claims 1 to 5, wherein the phase difference layer is formed of a liquid crystal compound.