JP7238328B2 - Polarizing plate and image display device using the same - Google Patents

Description

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

It has been known that when a birefringent film such as a polyester film is used under the environment of a fluorescent lamp or a cold cathode tube light source, iridescence caused by retardation occurs. Therefore, optically isotropic cellulose-based films have been used as protective films for polarizers used in liquid crystal displays and the like.

Recently, a technique has been proposed to eliminate iridescence by combining a film having a high retardation with a white light source having a continuous emission spectrum (e.g., Patent Document 1, Patent Document 2, etc.), which is compatible with polarized sunglasses. It has been put to practical use as a depolarizing film or a polarizer protective film in liquid crystal displays and the like. However, this technology is improved when using a light source with a sharp emission peak in the red region of the emission spectrum, such as a cold cathode tube light source or a KSF phosphor (a phosphor in which Mn is added to K ₂ SiF ₆ crystal). There was room for In addition, the film needs to be thick in order to ensure a high retardation, and there is a fear that it will not be able to sufficiently cope with the thinning of image display devices in recent years.

As a depolarizing film for a liquid crystal display using a light source with a steep emission peak, by providing unevenness on the surface of the film having birefringence, it is possible to locally reduce the wavelength to λ/4 or more within a region smaller than the level visible to the naked eye. A film in which retardation is generated has been proposed (for example, Patent Document 3). However, such prior art has problems such as poor image definition, low contrast, and in a strong external light environment, the screen becomes white and the image is difficult to see.

JP 2011-215646 A WO2011/162198 JP 2017-161599 A

The present invention has been made against the background of such problems of the prior art. That is, an object of the present invention is to provide a polarizing plate capable of suppressing iridescence and ensuring high transparency and image clarity when used in an environment of a light source having a steep emission peak, and an image display using the same. It is to provide a device and the like.

The present inventor has completed the present invention as a result of intensive studies to achieve this object.
That is, the present invention includes the following aspects.
Section 1.
A polarizing plate in which a polarizer having a thickness of 30 μm or less and a laminated film are laminated, wherein the laminated film has a base film and an optically isotropic layer and has all of the following characteristics.
(a) At least one surface of the substrate film is uneven, and the arithmetic mean roughness (Ra) of the uneven surface is 0.2 to 10 μm.
(b) The refractive index anisotropy (Bfnx-Bfny) of the base film is from 0.04 to 0.2.
(c) An optically isotropic layer is provided on the uneven surface of the base film, and the refractive index of the optically isotropic layer is from Bfny−0.15 to Bfnx+0.15.
(However, the refractive index in the slow axis direction of the base film is Bfnx, and the refractive index in the fast axis direction is Bfny.)
Section 2.
Item 2. The polarizing plate according to Item 1, wherein the polarizer is a polarizer in which a dichroic dye is adsorbed to polyvinyl alcohol.
Item 3.
Item 2. The polarizing plate according to Item 1, wherein the polarizer is a polarizer obtained by blending a dichroic dye with a liquid crystalline compound.
Section 4.
An image display device comprising the polarizing plate according to any one of Items 1 to 3.

The polarizing plate of the present invention can suppress iridescence and ensure high transparency and image clarity when used in an environment of a light source having a sharp emission peak.

The polarizing plate of the present invention preferably comprises a laminate of a polarizer and a laminated film having a thickness of 30 μm or less. The laminated film preferably has an optically isotropic layer on the uneven surface of the substrate film having the uneven surface (roughened surface). In addition, when it is simply called a laminated film below, this shall be meant.
(Base film)
First, the base film will be explained.

At least the base film is not particularly limited as long as it can have refractive index anisotropy, and examples thereof include polyester, polyamide, polystyrene, syndiotactic polystyrene, polyamide, and polycarbonate. Among them, polyester is preferable because a film having high refractive index anisotropy can be easily obtained. Examples of polyester include polyethylene terephthalate, polyethylene naphthalate, polytetramethylene terephthalate, polytrimethylene terephthalate, etc. Among them, polyethylene terephthalate and polyethylene naphthalate are preferred. These polyesters include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, and ethylene glycol, as long as they do not impair the mechanical properties, heat resistance, and dimensional stability of the film (for example, 10 mol % or less). . For example, in the case of a polyethylene terephthalate polymer, 1 to 2 mol of diethylene glycol, which is a by-product, is usually copolymerized during polymerization, and such a by-product may be contained.

The base film has birefringence. The lower limit of the slow axis refractive index (Bfnx) of the base film is preferably 1.65, more preferably 1.66, still more preferably 1.67, and particularly preferably 1.68. The upper limit of the slow axis direction refractive index (Bfnx) of the base film is preferably 1.73, more preferably 1.72, still more preferably 1.71, and particularly preferably 1.7.

The lower limit of the fast axis refractive index (Bfny) of the base film is preferably 1.53, more preferably 1.55, still more preferably 1.56, and particularly preferably 1.57. The upper limit of the fast axis direction refractive index (Bfny) of the base film is preferably 1.62, more preferably 1.61, still more preferably 1.6.

The lower limit of the refractive index anisotropy (ΔBfNxy=Bfnx−Bfny) of the substrate film is preferably 0.04, more preferably 0.05, still more preferably 0.06, and particularly preferably 0.07. When the lower limit is 0.04 or more, iridescence can be eliminated more effectively. The upper limit of the refractive index anisotropy of the substrate film is preferably 0.2, more preferably 0.18, still more preferably 0.17, and particularly preferably 0.16. When the upper limit is 0.2 or less, the mechanical strength in the fast axis direction can be adjusted within a practical range, and production is facilitated. The refractive index of the base film is a value measured under the condition of a wavelength of 589 nm.

The lower limit of the thickness of the base film before providing the uneven surface (before roughening) is preferably 15 μm, more preferably 20 μm, and still more preferably 25 μm. If the lower limit is 15 μm or more, excellent mechanical strength is obtained even if the thickness is reduced when the unevenness is imparted. The upper limit of the thickness of the base film before the uneven surface is provided is preferably 100 μm, more preferably 80 μm, still more preferably 70 μm, particularly preferably 60 μm, and most preferably 50 μm. If the upper limit is 100 μm or less, it is excellent in handleability and suitable for thinning (for example, for use in thin image display devices).

The lower limit of the in-plane retardation (Re) of the base film before the uneven surface is provided is preferably 1500 nm, more preferably 2000 nm, still more preferably 2300 nm, and particularly preferably 2500 nm. When the lower limit is 1500 nm or more, iridescence can be eliminated more effectively. The upper limit of the in-plane retardation (Re) of the substrate film before imparting the uneven surface is preferably 10000 nm, more preferably 8000 nm, still more preferably 7000 nm, particularly preferably 6000 nm, and most preferably 5000 nm. is. When the upper limit is 10000 nm or less, it is suitable for thinning.

The lower limit of the ratio (Re/Rth) between the in-plane retardation (Re) and the thickness direction retardation (Rth) of the base film before the uneven surface is imparted is preferably 0.2, more preferably 0.5, and even more preferably. is 0.6. When the lower limit is 0.2 or more, iridescence can be eliminated more effectively. The upper limit of Re/Rth of the base film before the rough surface is provided is preferably 2, more preferably 1.5, still more preferably 1.2, and particularly preferably 1 from the viewpoint of mechanical strength.

The lower limit of the Nz coefficient of the base film is preferably 1.3, more preferably 1.4, still more preferably 1.45. When the lower limit is 1.3 or more, the mechanical strength in the fast axis direction is also excellent. The upper limit of the Nz coefficient of the base film is preferably 2.5, more preferably 2.2, even more preferably 2, particularly preferably 1.8, most preferably 1.7. When the upper limit is 2.5 or less, iridescence can be more effectively eliminated.

The lower limit of the plane orientation degree ΔP of the substrate film is preferably 0.08, more preferably 0.09, and still more preferably 0.1. When the lower limit is 0.08 or more, not only can iridescence be effectively eliminated, but also thickness unevenness of the film can be reduced. The upper limit of the plane orientation degree ΔP of the substrate film is preferably 0.15, more preferably 0.14, and still more preferably 0.13. When the upper limit is 0.15 or less, the refractive index anisotropy can be kept higher.

The substrate film is preferably uniaxially oriented in order to have refractive index anisotropy. Orientation can be carried out by a normal method suitable for each resin. For example, if the melted resin is extruded on a cooling roll to form a sheet, the cooling roll is set to a speed higher than the speed of the extruded resin, and the unstretched film that has been melted and extruded is heated. Examples include a method of stretching and orienting the film in the longitudinal direction with a group of rolled rolls, and a method of stretching and orienting the unstretched film melted and extruded in the transverse direction or oblique direction by heating in a tenter.

Among these, the method of orienting the base film includes a method of stretching and orienting a melted and extruded unstretched film in the longitudinal direction with a group of heated rolls, and a method of stretching the melted and extruded unstretched film. A method of orientation by heating in a tenter and stretching in a horizontal direction or an oblique direction is preferred. The draw ratio in the longitudinal direction is preferably 2.5 to 10 times, more preferably 3 to 8 times, and particularly preferably 3.3 to 7 times. The draw ratio in the transverse direction or oblique direction is preferably 2.5 to 10 times, more preferably 3 to 8 times, and particularly preferably 3.3 to 7 times.

In addition, even in the case of orientation in the machine direction, it is weak (about 2.2 times or less) before stretching in the machine direction in order to increase the mechanical strength in the direction perpendicular to the orientation direction and to adjust the shrinkage characteristics. 2) transverse stretching may be added, or weak transverse stretching (about 1.5 times or less) may be added after longitudinal stretching. Similarly, even in the case of orientation in the transverse direction, a weak (about 2.2 times (less than 1.5 times) or weaker (less than about 1.5 times) stretching in the machine direction may be added after the stretching in the transverse direction. Further, in order to further increase the orientation in the orientation direction, the film may be slightly shrunk in the machine direction during or after stretching in the transverse direction. The width after shrinkage is preferably from 0.7 to 0.995 times, more preferably from 0.8 to 0.99 times, particularly preferably from 0.9 to 0.98 times the width during stretching. The stretching in the longitudinal direction and the stretching in the transverse direction may be performed by a tenter-type simultaneous biaxial stretching machine.

The stretching temperature (and preheating temperature) is preferably 80 to 150° C. both in the machine direction and in the transverse direction. Moreover, after stretching, in order to ensure the heat resistance of the base film, it is preferable to heat set at a temperature higher than the heating temperature during stretching. The heat setting temperature is preferably 150 to 250°C, more preferably 170 to 245°C.

The base film preferably has a light transmittance of 20% or less at a wavelength of 380 nm. The light transmittance at a wavelength of 380 nm is more preferably 15% or less, even more preferably 10% or less, and particularly preferably 5% or less. The light transmittance at a wavelength of 380 nm is measured in the direction perpendicular to the plane of the film, and can be measured using a spectrophotometer (for example, Hitachi U-3500).

In order to keep the light transmittance of the base film at a wavelength of 380 nm to 20% or less, it is desirable to appropriately adjust the type and concentration of the ultraviolet absorber to be blended in the base film, and the thickness of the base film. The ultraviolet absorbent used in the present invention includes organic ultraviolet absorbents and inorganic ultraviolet absorbents. From the viewpoint of transparency, organic UV absorbers are preferred. Examples of organic UV absorbers include benzotriazole-based, benzophenone-based, cyclic iminoester-based, and combinations thereof, but are not particularly limited as long as the light transmittance is within the range described above. From the viewpoint of durability, benzotriazole-based and cyclic iminoester-based are particularly preferable. When two or more ultraviolet absorbers are used in combination, ultraviolet rays of different wavelengths can be absorbed at the same time, so that the ultraviolet absorption effect can be further improved.

In addition to the ultraviolet absorber, it is also preferable to incorporate various additives into the substrate film within a range that does not impair the effects of the present invention. Examples of additives include inorganic particles, heat-resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, light stabilizers, flame retardants, heat stabilizers, antioxidants, and anti-gelling agents. , surfactants, and the like. These additives can be used alone or in combination of two or more.
Moreover, in order to achieve high transparency, it is also preferred that the base film does not substantially contain particles. The term "substantially contains no particles" means, for example, in the case of inorganic particles, when the inorganic elements in the base film are quantified by fluorescent X-ray analysis, 50 ppm or less, preferably 10 ppm or less, particularly preferably less than the detection limit. means a content of

(Improvement of surface unevenness)
In the present invention, at least one surface of the substrate film has an uneven surface. The uneven surface may be provided only on one side of the base film, or may be provided on both sides. A substrate film having an uneven surface may be referred to as a roughened substrate film.

The lower limit of the arithmetic mean roughness (Ra) of the uneven surface of the roughened substrate film is preferably 0.2 μm, more preferably 0.4 μm, even more preferably 0.6 μm, and particularly preferably 0.7 μm. and most preferably 0.8 μm. The upper limit of Ra is preferably 10 μm, more preferably 7 μm, even more preferably 5 μm, particularly preferably 4 μm, most preferably 3 μm.

The lower limit of the root-mean-square roughness (Rq) of the uneven surface of the roughened substrate film is preferably 0.3 μm, more preferably 0.5 μm, still more preferably 0.7 μm, and particularly preferably 0.9. μm, most preferably 1 μm. The upper limit of Rq is preferably 13 μm, more preferably 10 μm, even more preferably 7 μm, particularly preferably 5 μm, most preferably 4 μm.

The lower limit of the ten-point average roughness (Rz) of the uneven surface of the roughened substrate film is preferably 1.0 μm, more preferably 2.0 μm, still more preferably 3.0 μm, and particularly preferably 3.5. μm, most preferably 4.0 μm. The upper limit of Rz is preferably 15 μm, more preferably 12 μm, even more preferably 10 μm, and particularly preferably 8 μm.

The lower limit of the maximum height (Ry) of the uneven surface of the roughened substrate film is preferably 2.0 μm, more preferably 3.0 μm, still more preferably 4.0 μm, and particularly preferably 4.5 μm. Yes, most preferably 5.0 μm. The upper limit of Ry is preferably 20 μm, more preferably 17 μm, even more preferably 15 μm, and particularly preferably 13 μm.

The lower limit of the maximum peak height (Rp) of the uneven surface of the roughened base film is preferably 1.0 μm, more preferably 1.5 μm, still more preferably 2.0 μm, and particularly preferably 2.5 μm. be. The upper limit of Rp is preferably 15 μm, more preferably 12 μm, even more preferably 10 μm, particularly preferably 8 μm.

The lower limit of the maximum valley depth (Rv) of the uneven surface of the roughened substrate film is preferably 1.0 μm, more preferably 1.5 μm, even more preferably 2.0 μm, and particularly preferably 2.5 μm. is. The upper limit of Rv is preferably 15 μm, more preferably 12 μm, even more preferably 10 μm, and particularly preferably 8 μm.

When the values of Ra, Rq, Rz, Ry, Rp, and Rv are at least the lower limits, iris spots can be eliminated more effectively.
Productivity is excellent when the values of Ra, Rq, Rz, Ry, Rp, and Rv are at least the upper limits.
Ra, Rq, Rz, Ry, Rp, and Rv are calculated from roughness curves measured using a contact roughness meter in accordance with JIS B0601-1994 or JIS B0601-2001.

By providing unevenness (roughening) on the surface of the base film, a retardation difference is provided in a minute area, and although there is coloring (rainbow spots) due to retardation in each area, the coloring is visually invisible. be able to. This retardation difference ΔRe can be represented by ΔRe=Ra×ΔBfNxy. The lower limit of ΔRe is preferably 30 nm, more preferably 50 nm, still more preferably 70 nm, particularly preferably 90 nm, most preferably 100 nm. When the lower limit is 30 nm or more, iridescence can be eliminated more effectively. The upper limit of ΔRe is preferably 1500 nm, more preferably 1000 nm, still more preferably 800 nm, particularly preferably 500 nm, most preferably 300 nm. When the upper limit is 1500 nm or less, productivity is also excellent.

The lower limit of the average spacing (Sm) of the unevenness of the roughened substrate film is preferably 5 µm, more preferably 10 µm, still more preferably 15 µm, particularly preferably 20 µm, and most preferably 25 µm. is. When the lower limit is 5 μm or more, the slope of the unevenness becomes gentle, and the image becomes clearer. The upper limit of the average spacing (Sm) of the unevenness of the roughened substrate film is preferably 500 μm, more preferably 450 μm, still more preferably 400 μm, particularly preferably 350 μm, most preferably 300 μm. is. When the upper limit is 500 μm or less, it is possible to prevent a feeling of coloring or a feeling of flickering due to the retardation of each minute region.
Sm is calculated from a roughness curve measured using a contact roughness meter in accordance with JIS B0601-1994.

The base film may become thinner than the original thickness by providing unevenness and roughening the surface. The lower limit of the thickness of the roughened substrate film is preferably 10 μm, more preferably 13 μm, even more preferably 15 μm, particularly preferably 18 μm, most preferably 20 μm. When the lower limit is 10 μm or more, sufficient strength as a protective film can be ensured. The upper limit of the thickness of the roughened substrate film is preferably 90 μm, more preferably 80 μm, even more preferably 70 μm, particularly preferably 60 μm, and most preferably 50 μm. When the upper limit is 90 μm or less, it is suitable for thinning.
The thickness of the roughened base film is determined by embedding the roughened base film in epoxy resin, cutting out a section of the cross section, and observing it under a microscope. , the thickness is measured at 10 points at equal intervals, and the average value is calculated.

The lower limit of the in-plane retardation (Re) of the roughened substrate film is preferably 1000 nm, more preferably 1300 nm, even more preferably 1500 nm, particularly preferably 1800 nm, and most preferably 2000 nm. be. When the lower limit is 1000 nm or more, iridescence can be more effectively eliminated. The upper limit of the in-plane retardation (Re) of the roughened base film is preferably 9000 nm, more preferably 7000 nm, even more preferably 6000 nm, particularly preferably 5000 nm, most preferably 4500 nm. be. When the upper limit is 9000 nm or less, it is suitable for thinning.

The method for providing unevenness is not particularly limited, and conventionally known methods for surface roughening treatment can be used. For example, sandblasting, sandpaper or file, treatment with a whetstone, etc., treatment with a sander (orbital sander, random sander, delta sander, belt sander, disc sander, roll sander, etc.), treatment with a metal brush, etc., chemical etching, mold Examples include shaping by pressing with. Of these, sandblasting, sanding, and chemical etching are preferred.
Sandblasting may be, for example, a method in which a roll-shaped base film is supplied to a centrifugal blast machine and an abrasive is projected onto the base film surface. In this case, the roughness can be adjusted by the type of abrasive, the size of the abrasive, the processing time, the speed of the rotor blades, and the like. Further, the sandblasting treatment may be a method in which a substrate film is attached to a glass plate, set in air blasting, and an abrasive is blown onto the surface of the substrate film. In this case, the roughness can be adjusted by the type of abrasive, the size of the abrasive, the spraying pressure, the treatment time, and the like.
The treatment with a sander is, for example, a method in which a roll-shaped base film is guided to a conveying device having a roll sander attached to a part of the roll surface of the film conveying roll (roll sander). good. In this case, the roughness can be adjusted by the type of sanding paper, the rotation speed of the roll sander, the transport speed of the film, and the like. Also, the processing direction can be adjusted by the angle between the roll sander and the film, the rotation speed of the roll sander, the transport speed of the film, and the like.
In addition, sanding is performed by attaching urethane foam to a glass plate, then attaching a base film on top of it, and sanding the surface of the base film in four directions: vertical, horizontal, and diagonal (45 degrees, 135 degrees). It may be a method of processing from. Roughness can be adjusted by the type of sanding disk of the sander, processing time, and the like.
In addition, after sanding and sandblasting, the treated surface may be further polished with sandpaper or the like in order to remove local projections.
Chemical etching may be a method of immersing in an acid or alkaline solution, washing with water, peeling off the masking film, and drying. Roughness can be adjusted by immersion time or the like. Chemical etching is basically a double-sided treatment, but in the case of single-sided treatment, for example, a masking film is adhered to one side of the substrate film.

(optical isotropic layer)
An optically isotropic layer is preferably provided on the uneven surface of the base film. The optically isotropic layer is preferably provided in contact with the uneven surface. "Provided in contact with" means that it is provided in direct contact with the uneven surface without interposing another layer. However, an easy-adhesion layer may be provided to improve the adhesion between the uneven surface and the optically isotropic layer. The thickness of the easy-adhesion layer is preferably a thickness that is not optically detectable, preferably 100 nm or less, more preferably 50 nm or less, and particularly preferably 20 nm or less. If the easy-adhesion layer satisfies the refractive index range of the optical isotropic layer described below, the easy-adhesion layer and the optically isotropic layer provided thereon together are regarded as one optically isotropic layer. be able to. Moreover, if the easy-adhesion layer has a sufficient thickness as an optically isotropic layer, the easy-adhesion layer may be regarded as an optically isotropic layer. By providing the optically isotropic layer, it is possible to reduce diffused reflection due to unevenness on the surface of the base film and ensure transparency. The preferable refractive index of the easy-adhesion layer is the same as the preferable refractive index range of the optically isotropic layer described below, and the method of adjusting the refractive index is also the same.

The lower limit of the refractive index of the optically isotropic layer is preferably Bfny-0.15, more preferably Bfny-0.12, even more preferably Bfny-0.1, even more preferably Bfny-0.08, and particularly preferably Bfny, most preferably Bfny+0.02.
The upper limit of the refractive index of the optically isotropic layer is preferably Bfnx+0.15, more preferably Bfnx+0.12, even more preferably Bfnx+0.1, even more preferably Bfnx+0.08, and particularly preferably Bfnx, most preferably Bfnx-0.02.
Within the above range, the contrast or sharpness of the image can be maintained, and the phenomenon that the screen becomes whitish when exposed to strong external light can be suppressed.

The lower limit of the refractive index of the optically isotropic layer is preferably 1.44, more preferably 1.47, even more preferably 1.49, even more preferably 1.51, and particularly preferably 1.53, more particularly preferably 1.55, most preferably 1.57, most particularly preferably 1.59. The upper limit of the refractive index of the optically isotropic layer is preferably 1.85, more preferably 1.83, even more preferably 1.80, still more preferably 1.78, and particularly preferably 1.76, more particularly preferably 1.74, most preferably 1.72, still most preferably 1.70, most particularly preferably 1.68. By setting the ratio within the above range, the contrast or the sharpness of the image can be maintained, and the phenomenon that the screen becomes whitish when exposed to strong external light can be suppressed. The refractive index of the optically isotropic layer is also a value measured under the condition of a wavelength of 589 nm.

Although the composition of the optically isotropic layer is not particularly limited, acrylic, polystyrene, polyester, polycarbonate, polyurethane, epoxy resin, thioepoxy resin and the like are preferable. By appropriately adjusting the composition, it is possible to set the refractive index within the above range. For example, PMMA (polymethyl methacrylate) generally has a refractive index of about 1.49. In acrylic pressure-sensitive adhesives, a long-chain or branched alkyl group is often introduced, further lowering the refractive index. In order to increase the refractive index, it is effective to copolymerize an acrylic monomer having an aromatic group or copolymerize styrene.
Introducing a sulfur, bromine, fluorene group or the like into a polymer or resin is also a preferred method for increasing the refractive index. A thioepoxy resin or the like is preferable as the high refractive index resin.

Adding highly refractive fine particles to a polymer or resin is also a suitable method for adjusting the refractive index.
The refractive index of the high refractive fine particles is preferably 1.60 to 2.74. Fine particles of TiO ₂ , ZrO ₂ , CeO ₂ , Al ₂ O ₃ , BaTiO ₃ , Nb ₂ O ₅ , SnO ₂ and the like can be used as high refractive particles. The high-refractive fine particles preferably have an average primary particle size of 3 nm to 100 nm as observed by TEM (transmission electron microscope). These high refractive fine particles may be used singly or in combination of two or more.
In the specification, "average primary particle size" or "average particle size of primary particles" refers to a 50% volume cumulative particle size. More specifically, 200 primary particles of the particles are observed under a microscope at an appropriate magnification, the diameter of each is measured, the volume is calculated, and the 50% particle size of the cumulative volume is taken as the average primary particle size. do.

The optically isotropic layer is preferably crosslinked and cured. The curing method is not particularly limited, and radiation curing such as heat curing, ultraviolet rays, and electron beams is preferred. Cross-linking agents for curing include isocyanate compounds, epoxy compounds, carbodiimides, oxazoline compounds, amino resins such as melamine, polyfunctional acrylates, and the like.

The optical isotropic layer is produced by applying a coating agent comprising the above components to the uneven surface of the base film, applying the release film to the uneven surface of the base film, and transferring the optical isotropic layer to the uneven surface of the base film. The optically isotropic layer provided on the film can be laminated by a method such as bonding to the uneven surface of the substrate film. In this case, the coating agent is preferably dissolved or diluted with a solvent so as to have a viscosity that facilitates coating. Moreover, the coating agent may be solventless as long as it is a radiation curing type coating agent such as acrylic.

For example, a radiation-curing type coating agent such as acrylic usually contains a photopolymerizable compound.

Photopolymerizable compounds include photopolymerizable monomers, photopolymerizable oligomers, and photopolymerizable polymers, and these can be appropriately adjusted and used. The photopolymerizable compound is preferably a combination of a photopolymerizable monomer and a photopolymerizable oligomer or photopolymerizable polymer.

Photopolymerizable Monomer Photopolymerizable monomers are those having a weight average molecular weight of less than 1000. As the photopolymerizable monomer, a polyfunctional monomer having two (that is, bifunctional) or more photopolymerizable functional groups is preferable. As used herein, "weight average molecular weight" is a value obtained by dissolving in a solvent such as THF and converting to polystyrene by a conventionally known gel permeation chromatography (GPC) method.

Examples of polyfunctional monomers include tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, di Pentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol Penta(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, isocyanurate tri(meth)acrylate, isocyanurate di(meth)acrylate, polyester tri(meth)acrylate, polyester di( meth)acrylate, bisphenol di(meth)acrylate, diglycerin tetra(meth)acrylate, adamantyl di(meth)acrylate, isobornyl di(meth)acrylate, dicyclopentane di(meth)acrylate, tricyclodecane di(meth)acrylate, Those modified with PO, EO or the like can be mentioned.

Among these, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPPA) and the like are preferable from the viewpoint of obtaining a functional layer with high hardness.

Photopolymerizable Oligomer The photopolymerizable oligomer has a weight average molecular weight of 1,000 or more and less than 10,000. As the photopolymerizable oligomer, a bifunctional or higher polyfunctional oligomer is preferable. Polyfunctional oligomers include polyester (meth)acrylate, urethane (meth)acrylate, polyester-urethane (meth)acrylate, polyether (meth)acrylate, polyol (meth)acrylate, melamine (meth)acrylate, and isocyanurate (meth)acrylate. Acrylate, epoxy (meth)acrylate, and the like.

Photopolymerizable Polymer The photopolymerizable polymer has a weight average molecular weight of 10,000 or more, preferably 10,000 or more and 80,000 or less, more preferably 10,000 or more and 40,000 or less. If the weight-average molecular weight exceeds 80,000, the resulting laminated film may have poor appearance due to poor coating suitability due to its high viscosity. As the photopolymerizable polymer, a polyfunctional polymer having two or more functionalities is preferable. Polyfunctional polymers include urethane (meth)acrylate, isocyanurate (meth)acrylate, polyester-urethane (meth)acrylate, epoxy (meth)acrylate and the like.

The coating agent may contain a polymerization initiator, a cross-linking agent catalyst, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a leveling agent, a surfactant, and the like, in addition to the above components.

Alternatively, the melted optically isotropic layer composition is extruded and laminated on the uneven surface of the base film, or the melted optically isotropic layer composition is extruded between the uneven surface of the base film and another film. A method such as lamination is also preferred.

The optically isotropic layer has a function of reducing irregular reflection on the uneven surface by being provided on the uneven surface, but may also have other functions. The optically isotropic layer may have functions such as a hard coat layer, an antireflection layer, an antiglare layer, and an antistatic layer. Also, the optically isotropic layer may be another film or sheet, a pressure-sensitive adhesive layer or an adhesive layer for bonding to a constituent member of a device.

The lower limit of the thickness of the optically isotropic layer is preferably 0.5 μm, more preferably 1.0 μm, still more preferably 2 μm, particularly preferably 3 μm, most preferably 4 μm. When the thickness is 0.5 μm or more, the unevenness of the substrate film can be flattened, the haze can be reduced, and the sharpness can be improved.
The upper limit of the thickness of the optically isotropic layer is preferably 30 μm, more preferably 25 μm, still more preferably 20 μm, particularly preferably 15 μm, most preferably 10 μm. When the thickness is 30 μm or less, it is suitable for thinning.
The thickness of the optically isotropic layer is the value obtained by subtracting the thickness of the roughened base film from the thickness of the laminated film described later.

The upper limit of the in-plane retardation of the optically isotropic layer is preferably 50 nm, more preferably 30 nm, even more preferably 10 nm, and particularly preferably 5 nm, from the viewpoint of suppressing the occurrence of iridescence.

The upper limit of the refractive index difference between the refractive index in the direction of the highest refractive index and the refractive index in the direction of the lowest refractive index of the optically isotropic layer is preferably 0.01, and more It is preferably 0.007, more preferably 0.005, particularly preferably 0.003, most preferably 0.002.

(Laminated film)
The lower limit of the thickness of the laminated film is preferably 11 µm, more preferably 15 µm, even more preferably 18 µm, and particularly preferably 20 µm. When the lower limit is 12 μm or more, the strength of the laminated film is excellent, and handling in production or subsequent processing is facilitated.
The upper limit of the thickness of the laminated film is preferably 90 μm, more preferably 80 μm, even more preferably 70 μm, particularly preferably 60 μm, most preferably 50 μm. When the upper limit is 90 μm or less, it is suitable for thinning in various applications.
The thickness of the laminated film is calculated by embedding the laminated film in an epoxy resin, cutting out a section of the cross section, observing the section with a microscope, measuring the thickness at 10 points at equal intervals, and calculating the average value.

In the laminated film, only one side of the base film may be an uneven surface, but if the ΔRe of the base film is relatively low, or if the roughness of the uneven surface is relatively small, iridescence can be effectively suppressed. Therefore, it is preferable to make both surfaces of the base film uneven and to provide the optically isotropic layers on both surfaces.

The upper limit of the haze of the laminated film is preferably 10%, more preferably 7%, still more preferably 5%, particularly preferably 4%, most preferably 3%, and most preferably is 2.5%, most preferably 2%. When the upper limit is 10% or less, it is possible to more effectively suppress a decrease in contrast and a screen from becoming whitish when exposed to strong external light.

The laminated film may have two or more substrate films having an uneven surface (roughened surface), may have two or more optically isotropic layers, and may have an uneven surface (roughened surface). ) and a film or layer other than the optically isotropic layer.
Examples of lamination include types 1 to 4 below.
(Type 1) Base film (uneven surface)/optical isotropic layer (adhesive or adhesive)/Other film (Type 2) Base film (uneven surface)/optical isotropic layer (adhesive or adhesive) / (Uneven surface) Base film (type 3) Base film (uneven surface) / Optical isotropic layer (adhesive or adhesive) / Other film / Optical isotropic layer (adhesive or adhesive) / (Uneven Surface) Base film (Type 4) Other film/Optical isotropic layer (adhesive or adhesive)/(Uneven surface) Base film (uneven surface)/Optical isotropic layer (adhesive or adhesive)/Other Film When the ΔBfNxy of the base film with refractive index anisotropy is relatively small or the roughness of the unevenness is relatively small, it is preferable to adopt the configuration of type 2 to type 4. In the following description, the term "laminated film" includes the configurations of types 1 to 4 described above. In the case of Types 2 and 3, the slow axes of the two substrate films are preferably parallel or perpendicular to each other, preferably parallel from the viewpoint of ease of production. Here, "parallel or perpendicular" is allowed from 0 degree or 90 degrees, preferably ±10 degrees, further ±7 degrees, particularly ±5 degrees.

In addition, when referring to an adhesive or an adhesive layer in the specification, a coating agent for an adhesive is applied to an object and crosslinked or dried, or a substrate-less optical adhesive is transferred. means

The laminated film may further have various functional layers according to each application. Examples of various functional layers include a hard coat layer, an antiglare layer, an antireflection layer, a low reflection layer, a conductive layer, an antistatic layer, a colored layer, an ultraviolet absorption layer, an antifouling layer, and an adhesive layer.

(Application of laminated film)
The laminated film can be suitably used as a polarizer protective film or a depolarizing film.

(Polarizer)
First, the polarizing plate in which the laminated film and the polarizer are laminated will be described.
(Polarizer)
The polarizer can be a polyvinyl alcohol (PVA) compounded with a dichroic dye, a dichroic dye film or a coating film compounded with a liquid crystal compound with a dichroic dye, a stretched polyene film, or a wire grid type polarizer. There is no particular limitation such as a polarizer.
Among them, a polarizer in which a dichroic dye is adsorbed to PVA and a coated polarizer in which a dichroic dye is mixed with a liquid crystalline compound are preferable examples. In addition, in terms of being able to be made thin, a releasing supporting substrate laminated polarizer and a coating type polarizer described below are preferable.

In recent years, a thin polarizing plate has been demanded, and in order to cope with the thinning, the thickness of the polarizer is preferably 30 μm or less, more preferably 20 μm or less, still more preferably 15 μm or less, particularly preferably 10 μm or less, and most preferably 10 μm or less. is 8 μm or less. The thickness of the polarizer is preferably 0.1 μm or more, more preferably 0.3 μm or more, and still more preferably 0.5 μm or more.

(Polarizer in which dichroic dye is adsorbed on PVA)
First, a polarizer in which a dichroic dye is adsorbed on PVA will be described. A polarizer in which a dichroic dye is adsorbed on PVA is generally produced by immersing an unstretched PVA film in a bath containing a dichroic dye and then uniaxially stretching it, or by adding a dichroic dye to a uniaxially stretched PVA film. , followed by cross-linking in a boric acid bath.

The thickness of the polarizer using the PVA film is preferably 1-30 μm, more preferably 1.5-20 μm. More preferably, it is 2 to 15 μm. When it is 1 μm or more, it has sufficient polarization characteristics and is easy to handle. A thickness of 30 μm or less is suitable for thinning.

(Lamination of polarizer and laminated film)
As for the method of laminating the polarizer and the laminated film, if the polarizer is a polarizer in which a dichroic dye is adsorbed to PVA, it is preferable to bond the laminated film and the polarizer together. The adhesive for bonding is not particularly limited, and for example, conventionally used adhesives can be used without limitation. Among them, PVA-based water-based adhesives and UV-curable adhesives are preferable examples, and UV-curable adhesives are particularly preferable. Moreover, it is also preferable to use an adhesive.

A polarizer in which iodine is adsorbed on PVA may be used as a film as a single polarizer. A method of transferring a polarizer to a laminated film by using a polarizer laminated on a substrate (releasable supporting substrate-laminated polarizer) is also a preferred method. In this case, the thickness of the polarizer is preferably 15 μm or less, more preferably 10 μm or less, particularly preferably 8 μm or less, most preferably 6 μm or less. Even such a very thin polarizer can be easily handled because of the presence of the releasable supporting substrate, and the polarizer can be easily laminated on the laminated film. By using such a thin polarizer, it is possible to further reduce the thickness.
This technique has been introduced in many publications such as Japanese Patent Application Laid-Open No. 2001-350021 and Japanese Patent Application Laid-Open No. 2009-93074.

To give a specific example, first, PVA is applied to a releasable support substrate of a thermoplastic resin that is unstretched or uniaxially stretched perpendicularly to the longitudinal direction, and then the thermoplastic resin coated with PVA is released. The laminate of the moldable support substrate and PVA is stretched 2 to 20 times, preferably 3 to 15 times in the longitudinal direction. The stretching temperature is preferably 80 to 180°C, more preferably 100 to 160°C. The stretched laminate is immersed in a bath containing a dichroic dye to adsorb the dichroic dye. Dichroic dyes include, for example, iodine and organic dyes. When iodine is used, an aqueous solution of iodine and potassium iodide is preferred. It is preferable that the laminate to which the dichroic dye is adsorbed is immersed in an aqueous solution of boric acid for treatment, washed with water, and then dried. It should be noted that the film may be stretched 1.5 to 3 times as a preliminary stretch before adsorption of the dichroic dye. The above is an example, and the dichroic dye may be adsorbed before stretching, and the treatment with boric acid may be performed before the dichroic dye is adsorbed. It may be stretched in a medium or in a bath of boric acid solution. Also, these steps may be divided into multiple stages and combined.

Examples of the releasable supporting substrate include thermoplastic resins, preferably polyesters such as polyethylene terephthalate, polyolefins such as polypropylene and polyethylene, polyamides, and polyurethanes. The releasable support substrate may be subjected to corona treatment, or provided with a release coat layer or an easy-adhesion coat layer to adjust the release force.

A laminate of the laminated film and the polarizer is obtained by laminating the polarizer surface of the laminated polarizer with the releasable supporting substrate to the laminated film with an adhesive or pressure-sensitive adhesive, and then peeling off the releasable supporting substrate. may Generally used adhesives have a thickness of 3 to 30 μm, while adhesives have a thickness of 1 to 10 μm. For thinning, it is preferable to use an adhesive, especially an ultraviolet curable adhesive.

(Polarizer in which a dichroic dye is added to a liquid crystalline compound)
Next, a polarizer in which a liquid crystalline compound is mixed with a dichroic dye will be described.
(Orientation layer)
In the present invention, a polarizer (polarizing film) may be provided directly on the laminated film, or an orientation layer may be provided on the laminated film and the polarizing film may be provided thereon. The alignment film and the polarizing film may be collectively referred to as a polarizer, and when the polarizing film is provided on the laminated film without providing the alignment film, the polarizing film alone may be referred to as the polarizer.
The orientation layer controls the orientation direction of the polarizing film and can provide a polarizing film with a higher degree of polarization.
As the alignment layer, any alignment layer may be used as long as it can bring the polarizing film into the desired alignment state. Methods for imparting an orientation state to the orientation layer include, for example, rubbing the surface, oblique vapor deposition of an inorganic compound, formation of a layer having microgrooves, and the like. Further, a method of forming a photo-alignment layer in which molecules are aligned by irradiating polarized light to produce an alignment function is also preferable.
Two examples of a rubbing treatment alignment layer and a photo-alignment layer, which are preferable alignment layers, will be described below.

(Rubbing treatment orientation layer)
Polyvinyl alcohol and its derivatives, polyimide and its derivatives, acrylic resins, polysiloxane derivatives and the like are preferably used as the polymer material used for the rubbing treatment alignment layer.

First, the rubbing treatment alignment layer coating liquid containing the above polymer material and solvent is applied onto a base material, and then heat drying or the like is performed to obtain a rubbing treatment alignment layer precursor. The alignment layer coating solution may further contain a cross-linking agent.

As the solvent for the rubbing treatment alignment layer coating solution, any solvent that dissolves the polymer material can be used without limitation. Specific examples include alcohols such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol and cellosolve; ester solvents such as ethyl acetate, butyl acetate and gamma butyrolactone; ketone solvents; 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 rubbing treatment alignment layer coating solution can be appropriately adjusted depending on the type of polymer and the thickness of the alignment layer to be produced. A range of 3 to 10% by weight is particularly preferred.
As the coating method, known methods such as coating methods such as the gravure coating method, die coating method, bar coating method and applicator method, and printing methods such as the flexographic method are employed.
Although it depends on the base material, heat drying is preferably performed at a temperature in the range of 30°C to 170°C in the case of PET, more preferably 50°C to 150°C, and even more preferably 70°C to 130°C. If the drying temperature is low, it may be necessary to take a long drying time, resulting in poor productivity. If the drying temperature is too high, it will affect the orientation of the base material, reduce the retardation, increase the heat shrinkage of the base material, prevent the optical function from being achieved as designed, or deteriorate the flatness. There is The heat drying time may be, for example, 0.5 to 30 minutes, more preferably 1 to 20 minutes, and even more preferably 2 to 10 minutes.

The rubbing treatment can generally be carried out by rubbing the surface of the rubbing-treated alignment layer precursor in one direction with paper or cloth. In general, the surface is rubbed with a rubbing roller made of a fabric made of nylon, polyester, acrylic, or the like.
In order to provide a polarizing film having a transmission axis in a predetermined direction oblique to the longitudinal direction of the long base material, it is preferable that the rubbing direction of the rubbing treatment orientation layer also has an angle corresponding thereto. The adjustment of the angle can be carried out by adjusting the angle between the rubbing roller and the base material, and by adjusting the conveying speed of the base material and the rotational speed of the roller.

The thickness of the rubbed alignment layer is preferably 0.01 to 8 μm, more preferably 0.05 to 5 μm, especially 0.1 to 1 μm.

It is also possible to apply a rubbing treatment directly to the substrate film of the laminated film so that the surface of the substrate film has an orientation layer function, and this case is also included in the technical scope of the present invention.

(Photo-alignment layer)
The photo-alignment layer is, for example, a coating liquid containing a polymer or monomer having a photoreactive group and a solvent, applied to the laminated film, and irradiated with polarized light, preferably polarized ultraviolet light, thereby imparting alignment control force. Membrane. The photoreactive group generally means a group that exhibits liquid crystal alignment ability upon irradiation with light. Specifically, the photoreactive group is the origin of the liquid crystal alignment ability, such as orientation induction or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photodegradation reaction of molecules caused by irradiation with light. A photoreaction occurs. Among the photoreactive groups, those that cause a dimerization reaction or a photocrosslinking reaction are preferable from the viewpoint of excellent orientation and maintaining the smectic liquid crystal state of the polarizing film. As the photoreactive group capable of causing the above reaction, a group having an unsaturated bond, particularly a double bond is preferable, and consists of a C=C bond, a C=N bond, an N=N bond and a C=O bond. Groups having at least one selected from the group are particularly preferred.

Photoreactive groups having a C═C bond include, for example, vinyl groups, polyene groups, stilbene groups, stilbazole groups, stilbazolium groups, chalcone groups and cinnamoyl groups. Photoreactive groups having a C═N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, formazan groups, and groups having azoxybenzene as a basic structure. Photoreactive groups having a C=O bond include benzophenone, coumarin, anthraquinone and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups and halogenated alkyl groups.
Among them, a photoreactive group capable of causing a photodimerization reaction is preferable, and a cinnamoyl group and a chalcone group are preferable. It is preferable because it is easy to obtain. Furthermore, as a polymer having a photoreactive group, a polymer having a cinnamoyl group having a cinnamic acid structure at the end of the polymer side chain is particularly preferable. Examples of the structure of the polymer main chain include polyimide, polyamide, (meth)acryl, polyester and the like.

As a specific photo-alignment layer, for example, JP-A-2006-285197, JP-A-2007-76839, JP-A-2007-138138, JP-A-2007-94071, JP-A-2007-121721 , JP 2007-140465, JP 2007-156439, JP 2007-133184, JP 2009-109831, JP 2002-229039, JP 2002-265541, Patent JP 2002-317013, JP 2003-520878, JP 2004-529220, JP 2013-33248, JP 2015-7702, the light described in JP 2015-129210 Orientation layers may be mentioned.

As the solvent for the coating solution for forming the photo-alignment layer, any solvent can be used without limitation as long as it dissolves the polymer and monomer having a photoreactive group. As specific examples, those mentioned in the rubbing treatment orientation layer can be exemplified. It is also preferable to add a photopolymerization initiator, a polymerization inhibitor, various stabilizers, a combination thereof, or the like to the coating solution for forming the photo-alignment layer. Further, a polymer other than a polymer and a monomer having a photoreactive group or a monomer having no photoreactive group that can be copolymerized with a monomer having a photoreactive group may be added.

The concentration, coating method, and drying conditions of the coating liquid for forming the photo-alignment layer can also be exemplified by those mentioned for the rubbing treatment alignment layer. The thickness is also the same as the preferred thickness of the rubbing treatment alignment layer.

The thus-obtained photo-alignment layer precursor (a coating layer made of a coating solution for forming a photo-alignment layer) is, for example, irradiated with polarized light in a predetermined oblique direction with respect to the longitudinal direction of the substrate. Thus, it is possible to obtain a photo-alignment layer in which the direction of the alignment regulating force is oblique to the longitudinal direction of the long substrate.

Polarized light may be directly applied to the photo-alignment layer precursor, or may be applied through the laminated film.

The wavelength of the polarized light is preferably in a wavelength range in which the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, ultraviolet light with a wavelength in the range of 250 to 400 nm is preferred.
The polarized light source includes a xenon lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, an ultraviolet light laser such as KrF and ArF, and is selected from a high-pressure mercury lamp, an ultra-high-pressure mercury lamp and a metal halide lamp. is preferred.

Polarized light is obtained, for example, by passing light from the light source through a polarizer. For example, the direction of polarization can be adjusted by adjusting the polarization angle of the polarizer. Examples of the polarizer include polarizing filters, polarizing prisms such as Glan-Thompson and Glan-Taylor, and wire grid type polarizers. Preferably, the polarized light is substantially parallel light (collimated light).

For example, by adjusting the angle of polarized light for irradiation, the direction of the alignment regulating force of the photo-alignment layer can be arbitrarily adjusted.

^The irradiation intensity varies depending on the type and ^amount of the polymerization initiator and the polymer or monomer having a photoreactive group.

(polarizing film)
The polarizing film has a function of transmitting polarized light in only one direction, and preferably contains a dichroic dye.

(Dichroic dye)
A dichroic dye is a dye that has different absorbances in the long-axis direction and the short-axis direction of the molecule.

The dichroic dye preferably has an absorption maximum wavelength (λMAX) in the range of 300-700 nm. Such dichroic dyes include, for example, acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes and anthraquinone dyes, with azo dyes being preferred. Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakis azo dyes and stilbenazo dyes, preferably bisazo dyes and/or trisazo dyes. The dichroic dyes may be used alone or in combination, but it is preferable to combine two or more of them in order to adjust the color tone (achromatic color). It is more preferable to combine three or more types. In particular, it is preferable to combine three or more kinds of azo dyes.

Preferred azo dyes include dyes described in JP-A-2007-126628, JP-A-2010-168570, JP-A-2013-101328 and JP-A-2013-210624.

It is also a preferred form that the dichroic dye is a dichroic dye polymer introduced into the side chain of a polymer such as acryl. Examples of these dichroic dye polymers include polymers mentioned in JP-A-2016-4055 and polymers obtained by polymerizing the compounds of [Chemical 6] to [Chemical 12] of JP-A-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, in the polarizing film from the viewpoint of improving the orientation of the dichroic dye. , more preferably 1.0 to 15% by mass, particularly preferably 2.0 to 10% by mass.

The polarizing film preferably further contains a polymerizable liquid crystal compound in order to improve film strength, degree of polarization, and film homogeneity. The polarizing film may contain a polymer of a polymerizable liquid crystal compound.

(Polymerizable liquid crystal compound)
A polymerizable liquid crystal compound is a compound having a polymerizable group and exhibiting liquid crystallinity.
A polymerizable group means a group that participates in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group means a group capable of undergoing a polymerization reaction with an active radical generated from a photopolymerization initiator described below, an acid, or the like. Examples of the polymerizable group include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group and oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group and an oxetanyl group are preferred, and an acryloyloxy group is more preferred.
A compound exhibiting liquid crystallinity may be, for example, a thermotropic liquid crystal or a lyotropic liquid crystal, and may be a nematic liquid crystal or a smectic liquid crystal in a thermotropic liquid crystal.

The polymerizable liquid crystal compound is preferably a smectic liquid crystal compound, and more preferably a high-order smectic liquid crystal compound, in that higher polarizing properties can be obtained. When the liquid crystal phase formed by the polymerizable liquid crystal compound is a high-order smectic phase, a polarizing film with a higher degree of orientational order can be produced.

Specific preferred polymerizable liquid crystal compounds include, for example, JP-A-2002-308832, JP-A-2007-16207, JP-A-2015-163596, JP-A-2007-510946, JP-A-2013-114131. WO 2005/045485, Lub et al. Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996) and the like.

The content of the polymerizable liquid crystal compound in the polarizing film is preferably 70 to 99.5% by mass, more preferably 75 to 99% by mass, and further preferably 70 to 99.5% by mass in the polarizing film from the viewpoint of increasing the orientation of the polymerizable liquid crystal compound. It is preferably 80 to 97% by mass, particularly preferably 83 to 95% by mass.

The polarizing film can be provided, for example, by applying a polarizing film composition paint.
The polarizing film composition paint may contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a cross-linking agent, a combination thereof, and the like.

As the solvent, those mentioned as the solvent for the alignment layer coating solution are preferably used.

The polymerization initiator is not limited as long as it polymerizes the polymerizable liquid crystal compound, but is preferably a photopolymerization initiator that generates active radicals upon exposure to light. Examples of polymerization initiators include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts and sulfonium salts.

The sensitizer is preferably a photosensitizer, and examples thereof include xanthone compounds, anthracene compounds, phenothiazine, rubrene and the like.

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

As the polymerizable non-liquid crystal compound, one that is copolymerized with the polymerizable liquid crystal compound is preferable. (Meth)acrylates may be monofunctional or polyfunctional. By using polyfunctional (meth)acrylates, the strength of the polarizing film can be improved. When a polymerizable non-liquid crystal compound is used, it is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, particularly preferably 3 to 7% by mass, in the polarizing film. If it exceeds 15% by mass, the degree of polarization may decrease.

Examples of the cross-linking agent include compounds capable of reacting with functional groups of polymerizable liquid crystal compounds and polymerizable non-liquid crystal compounds, such as isocyanate compounds, melamine, epoxy resins, and oxazoline compounds.

A polarizing film can be obtained by directly applying a polarizing film composition paint onto a substrate film or an orientation layer, and optionally drying, heating and curing.

As a coating method, a coating method such as a gravure coating method, a die coating method, a bar coating method and an applicator method, or a known method such as a printing method such as a flexographic method is employed.

Drying is performed, for example, by guiding the base film after coating to a warm air dryer, an infrared dryer, or the like. The drying temperature is, for example, 30 to 170°C, more preferably 50 to 150°C, still more preferably 70 to 130°C. The drying time is preferably 0.5 to 30 minutes, more preferably 1 to 20 minutes, even more preferably 2 to 10 minutes.

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

When the polarizing film composition coating contains a polymerizable liquid crystal compound, it is preferably cured. Curing methods include heating and light irradiation, and light irradiation is preferred. Curing can fix the dichroic dye in an oriented state. Curing is preferably performed in a state in which a liquid crystal phase is formed in the polymerizable liquid crystal compound, and curing may be performed by light irradiation at a temperature exhibiting a liquid crystal phase.
Light for light irradiation includes visible light, ultraviolet light, and laser light. Ultraviolet light is preferred because it is easy to handle.

The irradiation intensity varies depending on the type and amount of the polymerization initiator, polymerizable liquid crystal compound, polymerizable non-liquid crystal compound, etc., but is preferably 100 to 10,000 mJ/cm ² , more preferably 200 to 5,000 mJ/cm ² at 365 nm.

In the polarizing film, for example, by applying a polarizing film composition paint on the alignment layer, the dichroic dye is oriented along the alignment direction of the alignment layer and has a polarization transmission axis in a predetermined direction. When the substrate is directly coated without providing a layer, the polarizing film can be oriented by irradiating polarized light to cure the polarizing film-forming composition. In this case, it is preferable to align the dichroic dye firmly along the alignment direction of the polymer liquid crystal by irradiating polarized light oblique to the longitudinal direction of the base material and heat-treating the base material.

The thickness of the polarizing film is, for example, 0.1 to 5 μm, preferably 0.3 to 3 μm, more preferably 0.5 to 2 μm.

The thickness of the coating type polarizer is preferably 0.1 to 10 μm, more preferably 0.3 to 7 μm, even more preferably 0.5 to 5 μm, and particularly preferably 0.5 to 3 μm.

(Lamination of polarizer and laminated film)
In addition to the method of directly providing an orientation layer or a polarizing layer on a laminated film and laminating, it is also a preferred method to provide a polarizing layer on a release film according to the above method and transfer this to the laminated film. Preferable examples of the release film include the release support substrate used in the above-described release support substrate laminated polarizer, and particularly preferable examples include a polyester film and a polypropylene film. The release film may be subjected to corona treatment, or may be provided with a release coat layer or an easy-adhesion coat layer to adjust the release force.

The method of transferring the polarizing layer to the laminated film is also the same as the above-described method for the releasable supporting substrate laminated polarizer.

(Angle between the transmission axis of the polarizer and the slow axis of the base film)
The angle formed by the transmission axis of the polarizer and the slow axis of the base film is not particularly limited. Vertical is preferred. Parallel or perpendicular is allowed from 0 or 90 degrees, preferably ±10 degrees, further ±7 degrees, especially ±5 degrees.

Further, when used as a polarizing plate that emits depolarized light such as when used on the viewing side of an image display device, the angle formed by the transmission axis of the polarizer and the slow axis of the base film is preferably 20 to 20. It is 70 degrees, more preferably 25 to 65 degrees, still more preferably 30 to 60 degrees, and particularly preferably 35 to 55 degrees.

The surface of the laminated film of the present invention on which the polarizer is laminated may be either the substrate film surface or the optically isotropic layer surface. When the optically isotropic layer is a layer such as a hard coat layer or an antiglare layer that imparts the function of the surface of the polarizing plate, it is preferable to provide a polarizer on the surface of the substrate film.

The above is a description of the case where the laminated film is used as a polarizer protective film and laminated with a polarizer. You can stick them together with an adhesive. In this case, the base film and the adhesive or pressure-sensitive adhesive constitute the laminate film referred to in the present invention. Also, an orientation layer corresponding to the optically isotropic layer in the present invention may be provided directly (or via an easy-adhesion layer) on the uneven surface of the substrate film.

The other surface of the polarizer of the polarizing plate thus obtained can take various forms depending on its purpose. Examples of the layer laminated on the other side of the polarizer include glass, a polarizer protective film having no birefringence, an optical compensation film, a λ/4 retardation film, a λ/2 retardation film, retardation (optical Compensation) Examples include a coating layer, a protective coat layer, those without these protective layers, and an adhesive layer. Note that the layer laminated on the other surface of the polarizer may be a laminated film. The laminated films laminated on each surface of the polarizer may be the same or different in terms of composition, thickness, and the like.

Examples of non-birefringent polarizer protective films include TAC films, acrylic films, cyclic olefin films, and polypropylene films.
Examples of optical compensation films include those having positive or negative A-plate and C-plate characteristics, and the surfaces of the above films, polycarbonate films, TAC films, etc., coated with rod-like liquid crystal compounds or discotic liquid crystal compounds. and so on. These are appropriately selected as the polarizing plate of the liquid crystal display according to the characteristics of the liquid crystal cell.
λ / 4 retardation film, and λ / 2 retardation film can be obtained by the same method as the optical compensation film, these are used, for example, circularly polarizing plate, suitable for antireflection film such as organic EL display device is. The thickness of these layers is preferably 10-50 μm, more preferably 15-40 μm.

For thinning of the image display device, the film is not used on the other side of the polarizer, and a retardation (optical compensation) coating layer, a protective coating layer, those without these protective layers, an adhesive layer, etc. are used. Used.
As the retardation (optical compensation) coating layer, there is a method of coating a liquid crystal compound on the polarizer, or a method of separately providing a retardation layer on a release film and transferring it. In particular, when thinning the polarizing plate, a liquid crystalline polarizer or a polarizer that transfers a polarizer laminated on a substrate is preferably used.

(Image display device)

The image display device preferably includes the polarizing plate described above.
The image display device preferably has a light source side polarizing plate, an image display cell, and a viewing side polarizing plate in this order.
The above-described polarizing plate is preferably used as either a light source side polarizing plate or a viewer side polarizing plate, and it is also preferable to use both. The laminated film is preferably used as a polarizer protective film on the opposite side of the image display cell.

The light sources (backlights) for liquid crystal display devices include blue light emitting diodes and yellow phosphor light sources, blue, green and red light emitting diode light sources, blue light emitting diodes, green phosphors, and red phosphor light sources, and wavelength conversion using quantum dots. A light source (QD light source), an organic EL light source, a semiconductor laser light source, a cold cathode tube, or the like can be used without particular limitation.

In the case of a polyester polarizer protective film with high retardation, even with a light source with a steep emission peak, or a blue light emitting diode and a yellow phosphor light source, if the thickness of the polarizer protective film is reduced, iridescence may occur. However, in a polarizing plate using a laminate film as a polarizer protective film, even in these cases, the rainbow spots are eliminated to the extent that they cannot be recognized.
A light source preferable for thinning includes a light source using a light emitting diode, and includes a light source using a blue light emitting diode and a yellow phosphor, a QD light source, and a light source using a KSF phosphor for the red region (KSF light source). Moreover, an organic EL light source is also mentioned as a preferable light source.

Also, the image display device may be an organic EL display device. The organic EL display device preferably has a circularly polarizing plate. The circularly polarizing plate is preferably a polarizing plate arranged on the viewing side of the display cell.
The laminated film can also be suitably used as a polarizer protective film for a circularly polarizing plate (especially as a polarizer protective film on the opposite side of the display cell). In particular, it can be made thinner, and is suitably used as a polarizer protective film for a circularly polarizing plate of a flexible type (foldable type) organic EL display device.

Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the following examples, and it is possible to carry out the present invention with appropriate modifications within the scope of the gist of the present invention. All of them are included in the technical scope of the present invention.
Methods for evaluating physical properties in Examples are as follows.

(1) Slow axis refractive index (Bfnx), fast axis refractive index (Bfny), and refractive index anisotropy (ΔBfNxy) of the base film
Using a molecular orientation meter (MOA-6004 type molecular orientation meter manufactured by Oji Keisoku Co., Ltd.), the orientation axis direction of the base film before roughening is determined, and the orientation axis direction is 4 cm so that the long side becomes. A 2 cm x 2 cm rectangle was cut out and used as a measurement sample. The biaxial refractive index (Bfnx, Bfny) and the refractive index (Bfnz) in the thickness direction of this sample were measured using an Abbe refractometer (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm). , and the absolute value of the biaxial refractive index difference (|Bfny−Bfnx|) was defined as the refractive index anisotropy (ΔBfNxy). The refractive index of the roughened substrate film can be measured by polishing the roughened surface with water-resistant emery paper or the like to flatten the roughened surface.

(2) Thickness d of raw film
Using an electric micrometer (Millitron 1245D manufactured by Fineruff Co.), the thickness was measured at five points, and the average value was obtained.

(3) In-plane retardation (Re)
The in-plane retardation (Re) was obtained from the product (ΔBfNxy×d) of the refractive index anisotropy (ΔBfNxy) and the film thickness d (nm).

(4) Nz Coefficient A value obtained by |Bfnx−Bfnz|/|Bfnx−Bfny| was used as the Nz coefficient.

(5) Degree of plane orientation (ΔP)
A value obtained by (Bfnx+Bfny)/2-Bfnz was defined as the degree of planar orientation (ΔP).

(6) Retardation in thickness direction (Rth)
The retardation in the thickness direction is obtained by multiplying the two birefringences ΔBfNxz (=|Bfnx−Bfnz|) and ΔBfNyz (=|Bfny−Bfnz|) when viewed from the cross section in the thickness direction of the film by the film thickness d. is a parameter that indicates the average retardation obtained by Bfnx, Bfny, Bfnz and the film thickness d (nm) are obtained in the same manner as described above, and the average value of (ΔBfNxz×d) and (ΔBfNyz×d) is calculated to calculate the thickness direction retardation (Rth). Calculated: Rth=(ΔBfNxz×d+ΔBfNyz×d)/2.

(7) Surface roughness (Ra, Rq, Rz, Ry, Rp, Rv, Sm)
Each parameter of the surface roughness is obtained from a roughness curve measured using a contact roughness meter (Mitutoyo, SJ-410, detector: 178-396-2, stylus: standard stylus 122AC731 (2 μm)). asked. The settings are as follows.
Curve: R
Filter: GAUSS
λc: 0.8mm
λs: 2.5 µm
Measuring length: 5mm
Measurement speed: 0.5mm/s
Rq was determined according to JIS B0601-2001, and others were determined according to JIS B0601-1994.

(8) Thickness of optically isotropic layer The thickness of the roughened base film and laminated film was determined by embedding each film in epoxy resin, cutting out a section of the cross section, and observing it under a microscope. The thickness was measured and taken as the average value. A polarizing microscope was used when the interface was difficult to see. In addition, the uneven surface of the roughened base film was based on the center of the convex portion and the concave portion in the field of view. The thickness of the optically isotropic layer was determined by subtracting the thickness of the roughened base film from the thickness of the laminated film.

(9) Refractive index of optically isotropic layer Under the same conditions as in the case of providing an optically anisotropic layer on a release film on an uneven surface, the refractive index of a sample peeled off from the release film was measured so as to have a thickness of about 20 μm. It was measured in the same manner as the base film. It was confirmed that nx, ny, and nz are the same value.

(Production of easy-adhesion layer component)
(Polymerization of polyester resin)
194.2 parts by weight of dimethyl terephthalate, 184.5 parts by weight of dimethyl isophthalate, and 14.8 parts by weight of dimethyl-5-sodium sulfoisophthalate were added to a stainless steel autoclave equipped with an agitator, thermometer, and partial reflux condenser. , 233.5 parts by mass of diethylene glycol, 136.6 parts by mass of ethylene glycol, and 0.2 parts by mass of tetra-n-butyl titanate were charged, and transesterification was carried out at a temperature of 160° C. to 220° C. over 4 hours. Then, the temperature was raised to 255° C., and the pressure in the reaction system was gradually reduced, followed by reaction under a reduced pressure of 30 Pa for 1 hour and 30 minutes to obtain a copolymerized polyester resin. The resulting copolymerized polyester resin was pale yellow and transparent. When the reduced viscosity of the copolymerized polyester resin was measured, it was 0.70 dl/g. The glass transition temperature by DSC was 40°C.

(Preparation of polyester aqueous dispersion)
A reactor equipped with a stirrer, a thermometer and a reflux device was charged with 30 parts by mass of a copolymer polyester resin and 15 parts by mass of ethylene glycol n-butyl ether, heated at 110° C. and stirred to dissolve the resin. After the resin was completely dissolved, 55 parts by mass of water was gradually added to the polyester solution with stirring. After the addition, the liquid was cooled to room temperature while stirring to prepare a milky white polyester water dispersion having a solid content of 30% by mass.

(Polymerization of block polyisocyanate-based cross-linking agent used in easy-adhesion layer)
A flask equipped with a stirrer, a thermometer, and a reflux condenser was charged with 100 parts by mass of a polyisocyanate compound having an isocyanurate structure made from hexamethylene diisocyanate (Duranate TPA, manufactured by Asahi Kasei Chemicals) and 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 and held at 70° C. for 4 hours in a nitrogen atmosphere. After that, the temperature of the reaction solution was lowered to 50° C., and 47 parts by mass of methyl ethyl ketoxime was added dropwise. By measuring the infrared spectrum of the reaction solution, it was confirmed that the absorption of isocyanate groups had disappeared, and an aqueous blocked polyisocyanate dispersion having a solid content of 75% by mass was obtained.

(Adjustment of coating liquid for easy adhesion layer)
A P1 coating solution was prepared by mixing the following coating agents.
Water 50.00% by mass
Isopropanol 33.00% by mass
Polyester water dispersion 12.00% by mass
Block isocyanate-based cross-linking agent 0.80% by mass
Particles 1.40% by mass
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (organotin compound solid content concentration 14% by mass) 0.30% by mass
Surfactant 0.50% by mass
(Silicone type, solid content concentration 10% by mass)

(Manufacture of polyester resin for film)
(Production Example 1-Polyester X)
When the temperature of the esterification reactor reaches 200° C., 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol are charged, and 0.017 parts by mass of antimony trioxide as a catalyst is added while stirring. , 0.064 parts by mass of magnesium acetate tetrahydrate, and 0.16 parts by mass of triethylamine were charged. Then, the pressure was increased and the temperature was increased, and the pressure esterification reaction was performed under the conditions of gauge pressure 0.34 MPa and 240° C., then the pressure in the esterification reactor was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. . Furthermore, the temperature was raised to 260° C. over 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added. After 15 minutes, dispersion treatment was performed with a high-pressure disperser. After 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reactor, and polycondensation reaction was performed at 280°C under reduced pressure.

After the polycondensation reaction is completed, filtration is performed with a NASLON (registered trademark) filter having a 95% cut diameter of 5 μm, extruded from the nozzle in strand form, and cooling water that has been pre-filtered (pore size: 1 μm or less) is filtered. It was cooled, solidified and cut into pellets. The resulting polyethylene terephthalate resin (X) had an intrinsic viscosity of 0.62 dl/g and contained substantially no inert particles or internal precipitated particles. (Hereinafter abbreviated as PET (X).)

(Production of raw films A and B)
PET (X) resin pellets containing no particles as a raw material for film are supplied to an extruder, extruded in a sheet form from a nozzle, and then wound around a casting drum with a surface temperature of 30 ° C. using an electrostatic casting method. It was cooled and solidified to produce an unstretched film. Next, the P1 coating liquid was applied to both sides of this unstretched PET film by a reverse roll method so that the coating amount after drying was 0.12 g / m ² , and then led to a dryer and dried at 80 ° C. for 20 seconds. bottom.

The unstretched film with the coating layer formed thereon was guided to a tenter stretching machine, and while holding the ends of the film with clips, was guided to a hot air zone at a temperature of 135° C. and stretched 3.8 times in the width direction. Next, while maintaining the width stretched in the width direction, it was treated at a temperature of 225 ° C. for 30 seconds, and then cut at both ends of the film cooled to 130 ° C. with a shear blade, and a tension of 0.5 kg / mm ² After cutting off the selvages, the film was wound up to obtain a raw film A having a film thickness of 80 μm.

A raw film B having a different film thickness was obtained in the same manner as the raw film A except that the thickness of the unstretched film was changed by increasing the line speed after casting.

(Manufacturing raw film C)
An unstretched film (coated with an easy-adhesion layer) produced by the same method as the raw film A is heated to 105 ° C. using a heated roll group and an infrared heater, and then a roll group with a peripheral speed difference. After being stretched 2.0 times in the running direction in the same manner as the raw film A, it was led to a hot air zone at a temperature of 135° C. and stretched 4.0 times in the width direction to obtain a raw film C.

(Original film D)
An unstretched film (coated with an easy-adhesion layer) produced by the same method as the raw film A is heated to 105 ° C. using a heated roll group and an infrared heater, and then a roll group with a peripheral speed difference. After the film was stretched 3.5 times in the running direction, it was led to a hot air zone at a temperature of 135° C. and stretched 3.5 times in the width direction by the same method as for raw film A, to obtain raw film D.

(Production of surface-roughened film)
Attach urethane foam to a glass plate, and then attach the periphery of the original film A with double-sided tape. 45 degrees and 135 degrees) to obtain a surface-roughened film A1.
The periphery of raw film A was attached to a glass plate with double-sided tape, set in a dry sandblaster, and treated by spraying an abrasive (sandblasting) to obtain surface-roughened film A2.
A masking film made of polypropylene film is attached to one side of the original film A, which is immersed in a 38% potassium hydroxide aqueous solution (95 ° C.) (chemical etching), washed with water, and then the masking film is peeled off and dried. A surface-roughened film A4 was obtained.
Various surface-roughened films shown in Table 2 were obtained from raw films A, B, C, and D by changing the belt sander conditions (sanding belt type, etc.) and sandblasting conditions (abrasive particle size, etc.). rice field.
A #320 sanding belt was used to manufacture B1 and C1, and a #180 sanding belt was used to manufacture A3 and D1. Abrasives of the sand blaster were used in the order of A5, A6, B2 and A2.
In addition, in order to eliminate the influence of local projections, the belt-sanded and sandblasted surfaces were lightly polished with #400 sandpaper.

(Production of laminated film (or polarizer protective film))
(Preparation of coating agent for optically isotropic layer)
As a coating agent for the optically isotropic layer, those shown in Table 3 were prepared.

Example 1
On the uneven surface of the surface roughened film A1 of 20 cm × 30 cm, the above-mentioned easy adhesion layer diluted 4 times with a solution of water / isopropanol = 2/1 is applied and dried to obtain an easy adhesion of about 30 nm. layer was established. Further, the coating agent a for the optically isotropic layer was applied thereon with an applicator, and then cured from the coated surface with a high-pressure mercury lamp to obtain a laminated film F1.

Examples 2-7, 9-14, and Comparative Examples 1-3
Laminated films F2 to F8 and F10 to F17 were obtained in the same manner as in Example 1, except that the type of surface-roughened film and/or coating agent was changed. Note that the laminated film F15 was provided with an optical isotropic layer on both sides.

Example 8
On the uneven surface of the surface roughened film A1 of 20 cm × 30 cm, the above-mentioned easy adhesion layer diluted 4 times with a solution of water / isopropanol = 2/1 is applied and dried to obtain an easy adhesion of about 30 nm. layer was established. Furthermore, after applying the coating agent a for the optically isotropic layer on it with an applicator, a surface nickel-plated metal plate mold having a concave-convex structure provided on the coated surface to provide anti-glare properties is superimposed, and the substrate film is coated. A laminated film F9 having an antiglare property in the optically isotropic layer was obtained by curing from the surface with a high-pressure mercury lamp.

Example 15
A solution of Vylon (registered trademark) 200 (RV200) (manufactured by Toyobo Co., Ltd.) in a 20% toluene/methyl ethyl ketone mixed solvent is applied to the uneven surface of the 20 cm × 30 cm roughened film B2, and then dried to form an optically isotropic layer. was established. The optically isotropic layers of the obtained two laminate films were superimposed and passed between rolls heated to 100° C., and the two laminate films were bonded together so that the slow axes were parallel to each other. Byron 200 has a refractive index of 1.55.

Example 16
The coating agent e for the optically isotropic layer was applied to the uneven surface of the surface-roughened film A1 of 20 cm×30 cm with an applicator to a thickness of 5 μm. A biaxially stretched PET film (E5200, thickness 12 μm, manufactured by Toyobo Co., Ltd.) cut to 20 cm × 30 cm is laminated on this coated surface, irradiated with a high-pressure mercury lamp from the A1 side to cure, and reinforced with a biaxially stretched PET film. A laminated film F19 was obtained.

(Evaluation of laminated film)
(Observation of rainbow spots)
The laminated film is placed between two polarizing plates arranged in crossed Nicols so that the slow axis is at 45 degrees with the transmission axis of the polarizing plate on the light source side, and the transmitted light is viewed from the front about 60 cm away from the polarizing plate on the viewing side. was observed, and the presence or absence of iridescence was evaluated according to the following criteria. A cold cathode tube was used as the light source.
○: No iridescence was observed △: Slight iridescence was observed ×: Iridescence was observed

(character sharpness)
The laminated film was placed at a position 1 cm above the newspaper, and whether characters on the newspaper (about 3.8 mm long and about 3.9 mm wide) could be recognized was evaluated according to the following criteria. In addition, since anti-glare processing has an influence on the anti-glare processing, evaluation was not performed.
A: Characters were clearly recognized.
◯: Slightly blurred, but recognized without problems.
△: Kanji other than kanji with a large number of strokes could be recognized.
x: Recognition was difficult.

Table 4 shows the physical properties and evaluation results of the laminated films of Examples 1 to 16 and Comparative Examples 1 to 3.

(Manufacture of polarizing plate)
(Preparation of coating agent for adhesive used as optical isotropic layer and optical adhesive sheet)
The adhesives and optical adhesive sheets shown in Table 5 were used.

Preparation of high refractive index adhesive k 30 parts by mass of 2-ethylhexyl acrylate, 70 parts by mass of ethoxylated o-phenylphenol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name: A-LEN-10), and azo as a polymerization initiator 0.25 parts by mass of bisisobutyronitrile was reacted in ethyl acetate to obtain an ethyl acetate solution (solid concentration: 30% by mass) of a copolymer (Mw=400,000).

(Manufacture of polarizer)
(Manufacturing of substrate-laminated polarizer)
An unstretched film having a thickness of 100 μm was prepared using PET (X) as a thermoplastic resin substrate, and an aqueous solution of polyvinyl alcohol having a degree of polymerization of 2400 and a degree of saponification of 99.9 mol% was applied to one side of the unstretched film. And dried to form a PVA layer to obtain a laminate.
The resulting laminate was stretched twice in the longitudinal direction between rolls having different peripheral speeds at 120° C. and wound up.
Next, the obtained laminate was treated with a 4% boric acid aqueous solution for 30 seconds, and then immersed in a mixed aqueous solution of iodine (0.2%) and potassium iodide (1%) for 60 seconds for dyeing. and then treated with a mixed aqueous solution of potassium iodide (3%) and boric acid (3%) for 30 seconds.
Furthermore, the obtained laminate was uniaxially stretched in the longitudinal direction in a mixed aqueous solution of boric acid (4%) and potassium iodide (5%) at 72 ° C., followed by washing with a 4% potassium iodide aqueous solution, After removing the aqueous solution with an air knife, the film was dried in an oven at 80° C., slit at both ends, and wound up to obtain a substrate laminated polarizer 1 having a width of 30 cm and a length of 1000 m.
The total draw ratio was 6.5 times, and the thickness of the polarizer was 5 μm. The thickness was read by embedding the base-material-laminated polarizer in an epoxy resin, cutting out a slice, and observing it with an optical microscope.

Example 17
After coating the adhesive coating agent i as an optically isotropic layer on the uneven surface of the 20 cm×30 cm surface-roughened film A1 with an applicator, the coated surface was cured with a high-pressure mercury lamp to form a laminate. After bonding the adhesive layer surface of the laminate and the polarizer surface of the substrate-laminated polarizer cut to 20 cm × 30 cm, the substrate of the substrate-laminated polarizer is peeled off, and the optical adhesive layer is laminated on the polarizer surface. Thus, a single-sided protective film polarizing plate P1 was obtained. The transmission axis of the polarizer and the slow axis of the base film were made parallel.

Comparative example 4
A polarizing plate P3 was obtained in the same manner, except that the optical adhesive sheet j was used as an optically isotropic layer on the uneven surface of the surface-roughened film A1.

Example 18
After coating the uneven surface of the surface-roughened film A1 of 20 cm×30 cm with a pressure-sensitive adhesive coating agent k as an optically isotropic layer using an applicator, it was dried at 100° C. to form a laminate. Polarizing plate P2 was obtained in the same manner as in Example 17.

Examples 19, 20, 21
An applicator was used to apply the coating agent b for the optically isotropic layer onto the uneven surface of the surface-roughened film A1 of 20 cm×30 cm. The polarizer surface of the substrate-laminated polarizer cut to 20 cm×30 cm was superimposed on the coated surface, and after curing by irradiation with a high-pressure mercury lamp from the A1 surface, the substrate of the substrate-laminated polarizer was peeled off. Further, an optical adhesive layer was laminated on the polarizer surface to obtain a polarizing plate polarizing plate P4 provided with a protective film only on one side.
Polarizing plates P5 and P6 were obtained in the same manner, except that e and f were used as the coating agents for the optically isotropic layer.

Table 6 summarizes the physical properties and evaluation of these polarizing plates obtained from each laminated film. Evaluation criteria are as described later.

(Production of polarizing plate using laminated films F1 to F19)
An ultraviolet curable acrylic adhesive was applied to the surfaces of the optically isotropic layers of the laminated films F1 to F8 and F10 to F17 using an applicator. After bonding the polarizer surface of the substrate-laminated polarizer cut to 20 cm × 30 cm to the coated surface, the laminate film surface is irradiated with a high-pressure mercury lamp to cure, and the substrate of the substrate-laminated polarizer is peeled off. Furthermore, an optical adhesive layer was laminated on the polarizer surface to obtain polarizing plates PF1c to PF8c and PF10c to PF17c having a protective film only on one side.
Further, polarizing plates PF1b to PF14b and PF16b to PF19b were obtained in the same manner as described above, except that the base film surfaces of the laminated films F1 to F14 and F16 to F19 were coated with an ultraviolet curable acrylic adhesive.
The transmission axis of the polarizer and the slow axis of the base film were made parallel.

PF4b2 and PF5b2 were obtained in the same manner as in the preparation of PF4b and PF5b, except that the transmission axis of the polarizer and the slow axis of the base film were perpendicular to each other.

Table 7 summarizes the evaluation of these polarizing plates obtained from each laminated film.

(Preparation of polarizing plate using organic dye compound as polarizer)
(Formation of photo-alignment layer)
(Synthesis of paint for photo-alignment layer)
Based on the descriptions of Examples 1, 2, and 3 of JP-A-2013-33248, a 5% by mass cyclopentanone solution of polymer (a) of the following formula (1) was produced.

(Formation of photo-alignment layer)
Laminated film F5 was cut into a size of A4, and the base film surface was coated with the photo-alignment layer paint having the above composition using a bar coater and dried at 80° C. for 1 minute to form a film with a thickness of 150 nm. Subsequently, the film was irradiated with polarized UV light to obtain a laminated film F5 laminated with a photo-alignment layer. The polarized plane of the irradiated UV was made parallel to the slow axis of the substrate.

(Formation of polarizing layer)
(Synthesis of polymerizable liquid crystal compound)
The description in paragraph [0134] of JP-A-2007-510946 and Lub et al. Recl. Trav. Chim. With reference to Pays-Bas, 115, 321-328 (1996), a compound (b) of the following formula (2) and a compound (c) of the following formula (3) were synthesized.

With reference to Example 1 of JP-A-63-301850, a dye (d) of the following formula (4) was synthesized.

A dye (e) of the following formula (5) was synthesized with reference to Example 2 of JP-B-5-49710.

A dye (f) of the following formula (6) was synthesized with reference to the method for producing the compound of general formula (1) in JP-B-63-1357.

(Formation of polarizing layer)
(B) 75 parts by mass, (C) 25 parts by mass, (D) 2.5 parts by mass, (E) 2.5 parts by mass, (F) 2.5 parts by mass, IRGACURE (R) 369E (manufactured by BASF) ) 6 parts by mass and 250 parts by mass of ortho-xylene are applied onto the laminate film F5 laminated with the photo-alignment layer using a bar coater, and dried at 110° C. for 3 minutes to form a film with a thickness of 2 μm. bottom. UV light was subsequently applied. Further, a commercially available optical adhesive sheet was laminated on the polarizer surface to obtain a polarizing plate PF5b-dy1.

A polarizing plate PF5b-dy2 was obtained in the same manner as the polarizing plate PF5b-dy1, except that the direction of polarized light irradiated during formation of the alignment layer was perpendicular to the slow axis of the base film.

Polarizing plates PF5b-dy3 and PF5b-dy4 were obtained in the same manner as the polarizing plates PF5b-dy1 and PF5b-dy2 except that a polarizer was provided on the optically isotropic layer surface of the laminated film F5.

(Formation of rubbing alignment layer)
Laminated film F5 was cut into a size of A4, and the base film surface was coated with a rubbing alignment layer paint having the following composition using a bar coater and dried at 120° C. for 3 minutes to form a film having a thickness of 200 nm. Subsequently, the surface of the obtained film was treated with a rubbing roll wrapped with a nylon raised cloth to obtain a laminated film F5 laminated with a rubbed orientation layer. Rubbing was performed in parallel with the slow axis direction of the substrate film.
Fully saponified polyvinyl alcohol Molecular weight 800 2 parts by mass Ion-exchanged water 100 parts by mass

(Formation of polarizing layer)
A polarizing plate PF5b-dy5 was obtained in the same manner as described above except that the alignment layer of the laminated film F5 laminated with the rubbed alignment layer was coated with the above coating material for the polarizing layer.
A polarizing plate PF5b-dy6 was obtained in the same manner as the polarizing plate PF5b-dy5, except that the rubbing direction was perpendicular to the slow axis direction of the base film.

Laminated film F5 was cut into a size of A4, and the optically isotropic layer surface was rubbed. The rubbing treatment was performed in parallel with the slow axis direction of the substrate film. A polarizing plate PF5b-dy7 was obtained in the same manner as described above except that the above paint for polarizing layer was applied onto the rubbing-treated surface of the laminated film F5.
A polarizing plate PF5b-dy8 was obtained in the same manner as the polarizing plate PF5b-dy7, except that the rubbing direction was perpendicular to the slow axis direction of the base film.

A biaxially stretched PET film having a release layer on its surface was provided with the above photo-alignment layer and a polarizing layer with a dye. The polarizing layer made of this dye is laminated with the adhesive surface of a film obtained by laminating an adhesive layer made of adhesive coating agent k as an optically isotropic layer on the uneven surface of the surface-roughened film A1 used in Example 18, After peeling off the biaxially stretched PET film, a commercially available optical adhesive sheet was laminated to obtain a polarizing plate P7. The transmission axis of the polarizer and the slow axis of the base film were arranged in parallel.

The results are summarized in Table 8.

(Evaluation of liquid crystal display device)
The polarizing plates on the viewing side and the light source side mounted on a liquid crystal display device (REGZA Z20X manufactured by Toshiba Corp.) having a KSF light source were peeled off, and the resulting polarizing plates were bonded instead. In the case of a polarizing plate using a TAC film laminated polarizer, a commercially available optical adhesive sheet is laminated on the TAC surface, and in the case of a polarizing plate having a protective film on only one side, an optical adhesive sheet laminated on the polarizer surface is used. The adhesive sheet surface for the tape was pasted together.
The transmission axis of the polarizer was made to be the same as the direction of the original liquid crystal display device. The portion of the liquid crystal cell that could not be covered by the polarizing plate was covered with black construction paper.
For the evaluation, confirmation of the iridescence and contrast of the image were observed.

(Observation of rainbow spots on liquid crystal display device)
The display of the liquid crystal display device was set to a single white color, and the presence or absence of rainbow spots was confirmed when viewed from the front and oblique directions.
○: No iridescence was observed △: Slight iridescence was observed ×: Iridescence was observed

(observation of contrast)
A landscape image was displayed on the liquid crystal display device, and the contrast from the front was observed by irradiating light from a tabletop fluorescent lamp from above.
⊚: Vivid contrast remained.
Good: A slight reduction in contrast was observed due to scattered light.
Δ: A decrease in contrast was observed, but the image could be observed.
×: Image became difficult to see due to scattered light

(Manufacture of circularly polarizing plate)
A λ/4 wavelength plate was adhered to the adhesive layer surface of the single-sided protective film polarizing plate P2 laminated with the above-described adhesive to prepare a circularly polarizing plate. The circularly polarizing plate of a smartphone using a commercially available organic EL was peeled off, and a circularly polarizing plate prepared instead was attached to the organic EL cell, and the image was observed. These circularly polarizing plates could be used without problems.

The polarizing plate of the present invention can suppress iridescence and ensure high transparency and image clarity when used in an environment of a light source having a steep peak.

Claims (7)

A polarizing plate in which a polarizer having a thickness of 30 μm or less and a laminated film are laminated, wherein the laminated film has a base film and an optically isotropic layer and has all of the following characteristics.
(a) At least one surface of the substrate film is uneven, and the arithmetic mean roughness (Ra) of the uneven surface is 0.4 to 4 μm.
(b) The refractive index anisotropy (ΔBfNxy) of the base film is 0.07 to 0.2.
(c) An optically isotropic layer is provided on the uneven surface of the base film, and the refractive index of the optically isotropic layer is from Bfny−0.15 to Bfnx+0.15 and is 1.57 or more. .
(However, the refractive index in the slow axis direction of the base film is Bfnx, the refractive index in the fast axis direction is Bfny , and ΔBfNxy=Bfnx−Bfny )
(d) The substrate film has a retardation difference (ΔRe) of 90 to 800 nm.
(However, ΔRe=Ra×ΔBfNxy)
(e) the substrate film has an in-plane retardation of 3139 to 9000 nm;
(f) Bfnx of the base film is 1.67 to 1.73.
(g) The base film is a polyester film.
(h) The optically isotropic layer is provided in direct contact with the irregular surface without any other layer interposed therebetween, or is provided only via the easy-adhesion layer. 2. The polarizing plate according to claim 1, wherein the base film has a plane orientation degree (ΔP) of 0.09 to 0.15. 3. The polarizing plate according to claim 1, wherein the optically isotropic layer has a refractive index of Bfny to Bfnx. 4. The polarizing plate according to claim 1, wherein the optically isotropic layer has a refractive index of Bfny+0.02 to Bfnx. 5. The polarizing plate according to any one of claims 1 to 4, wherein the polarizer is a polarizer in which a dichroic dye is adsorbed to polyvinyl alcohol. 5. The polarizing plate according to any one of claims 1 to 4, wherein the polarizer is a polarizer obtained by blending a dichroic dye with a liquid crystalline compound. An image display device comprising the polarizing plate according to any one of claims 1 to 6.