JP2019124909A - Laminated film and polarizing plate produced using the same - Google Patents

Abstract

To provide a laminated film which suppresses rainbow spots when used in an environment with a light source having a steep emission peak, secures high transparency and capability to present clear images, and minimizes external light reflection.SOLUTION: A laminated film is provided, which satisfies all the features below, comprises a base material film and an optically isotropic layer, and has an anti-reflection surface with a moth-eye structure on at least one side thereof. (a) The base material film has a rugged surface having an arithmetic mean roughness (Ra) in a range of 0.2-10 μm provided on at least one side thereof. (b) The base material film has a refractive index anisotropy (Bfnx-Bfny) in a range of 0.04-0.2. (c) An optically isotropic layer having a refractive index in a range of Bfny-0.15 to Bfnx+0.15 is provided on top of the rugged surface of the base material film, where Bfnx represents a refractive index of the base material film in a slow axis direction and Bfny represents a refractive index in a fast axis direction.SELECTED DRAWING: None

Description

  The present invention relates to a laminated film and a polarizing plate using the same.

  It has been known that when a film having birefringence, such as a polyester film, is used in the environment of a fluorescent lamp or a cold cathode tube light source, rainbow marks due to retardation occur. Therefore, a cellulose-based film having optical isotropy has been used as a protective film of a polarizer used for a liquid crystal display or the like.

Recently, a technique has been proposed for eliminating rainbow marks by combining a film having high retardation with a white light source having a continuous emission spectrum (for example, Patent Document 1, Patent Document 2 etc.), and it corresponds to polarized sunglasses. It has been put to practical use in liquid crystal displays and the like as a depolarizing film or a polarizer protective film. However, this technique is improved when using a light source having a sharp emission peak in the red region of the emission spectrum such as a cold cathode tube light source or a KSF phosphor (phosphor obtained by adding Mn to K ₂ SiF ₆ crystal). There was room for In addition, in order to ensure high retardation, the film needs to have a thickness, and there is a possibility that it can not sufficiently cope with the recent thinning of the image display apparatus.

  As a depolarizing film of a liquid crystal display using a light source having a sharp emission peak, unevenness is provided on the surface of the film having birefringence, so that λ / 4 or more is locally within a region smaller than the level visible to the naked eye. A film in which a phase difference is generated has been proposed (for example, Patent Document 3). However, such conventional techniques have a problem that the screen becomes white and the image is difficult to see in a strong external light environment where the image contrast is low.

JP, 2011-215646, A International Publication No. 2011/162198 JP, 2017-161599, A

  The present invention has been made on the background of the problems of the prior art. That is, an object of the present invention is to suppress rainbow marks, secure high transparency and vivid image displayability, and suppress reflection by external light when used in an environment of a light source having a sharp emission peak, etc. An object of the present invention is to provide a laminated film that can be used, a polarizing plate using the same, and the like.

As a result of intensive investigations to achieve such an object, the present inventor has completed the present invention.
That is, the present invention includes the following aspects.
Item 1.
A laminated film having a base film and an optically isotropic layer having all the following features, wherein at least one surface of the laminated film is an antireflective surface having a moth-eye structure.
(A) At least one surface of the base film is an uneven surface, and the arithmetic average roughness (Ra) of the uneven surface is 0.2 to 10 μm.
(B) The refractive index anisotropy (Bfnx-Bfny) of a base film is 0.04-0.2.
(C) The optically isotropic layer is provided on the uneven surface of the base film, and the refractive index of the optically isotropic layer is Bfny-0.15 to Bfnx + 0.15.
(However, let the refractive index in the slow axis direction of the base film be Bfnx and the refractive index in the fast axis direction be Bfny)
Item 2.
Item 2. A polarizing plate using the laminated film according to item 1 as a polarizer protective film.
Item 3.
The image display apparatus containing the polarizing plate of claim 2.

  The laminated film of the present invention suppresses rainbow marks, secures high transparency and vivid image displayability, and suppresses reflection by external light when used under an environment of a light source having a sharp emission peak. be able to.

The laminated film of the present invention preferably has an optically isotropic layer on the uneven surface of the base film having the uneven surface (roughened surface), and at least one of the surfaces is a reflection preventing surface having a moth-eye structure. . In addition, when only calling it a laminated | multilayer film or an anti-reflective film hereafter, this shall be meant.
(Base film)
First, the substrate film will be described.

  There is no particular limitation on at least the base film as long as it can give refractive index anisotropy, and polyester, polyamide, polystyrene, syndiotactic polystyrene, polyamide, polycarbonate and the like can be mentioned. Above all, polyester is preferable in that a film having a high refractive index anisotropy can be easily obtained. Examples of the polyester include polyethylene terephthalate, polyethylene naphthalate, polytetramethylene terephthalate, polytrimethylene terephthalate, etc. Among them, polyethylene terephthalate and polyethylene naphthalate are preferable. These polyesters are terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, ethylene glycol as long as mechanical properties, heat resistance and dimensional stability as a film are not impaired (for example, 10 mol% or less). Diethylene glycol, trimethylene glycol, tetramethylene glycol, and ethylene oxide (EO) 1-2 mole adduct of cyclohexanedimethanol bisphenol A may be copolymerized. For example, in the case of a polymer of polyethylene terephthalate, 1 to 2 moles of a by-product diethylene glycol is usually copolymerized during polymerization, but such a by-product may be contained.

  The base film has birefringence. The lower limit of the slow axis direction 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 axial direction 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 axial direction refractive index (Bfny) of the base film is preferably 1.62, more preferably 1.61, and still more preferably 1.6.

  The lower limit of the refractive index anisotropy (ΔBfNxy = Bfnx−Bfny) of the base 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, rainbow spots 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. If the upper limit is 0.2 or less, the mechanical strength in the fast axis direction can be adjusted to the practical range, and the manufacture is also facilitated. In addition, the refractive index of a base film is a value measured on the conditions of wavelength 589 nm.

  The lower limit of the thickness of the base film before the provision of the uneven surface (before the roughening) is preferably 15 μm, more preferably 20 μm, and still more preferably 25 μm. If the said minimum is 15 micrometers or more, even if thickness reduces at the time of uneven | corrugated provision, it has the outstanding mechanical strength. The upper limit of the thickness of the substrate film prior to the application of the uneven surface is preferably 200 μm, more preferably 150 μm, still more preferably 100 μm, particularly preferably 90 μm, and most preferably 80 μm. If the said upper limit is 200 micrometers or less, it is excellent in the handling property and suitable for making it thin (example: it uses for a thin image display apparatus).

  The lower limit of the in-plane retardation (Re) of the substrate film before the application of the uneven surface is preferably 2000 nm, more preferably 2500 nm, still more preferably 3000 nm, particularly preferably 3500 nm, most preferably 4000 nm. It is. Rainbow spots can be eliminated more effectively if the lower limit is 2000 nm or more. The upper limit of the in-plane retardation (Re) of the substrate film before the application of the uneven surface is preferably 30000 nm, more preferably 20000 nm, still more preferably 15000 nm, still more preferably 12000 nm, particularly preferably It is 10000 nm, more particularly preferably 9000 nm, most preferably 8000 nm and most particularly preferably 7500 nm. When the upper limit is 30000 nm or less, it is suitable for thinning.

  The lower limit of the ratio (Re / Rth) of the in-plane retardation (Re) to the retardation (Rth) in the thickness direction of the substrate film prior to the application of the uneven surface is preferably 0.2, more preferably 0.5, and still more preferably Is 0.6. When the lower limit is 0.2 or more, rainbow marks can be eliminated more effectively. The upper limit of Re / Rth of the substrate film before the provision of the uneven surface is preferably 2 in view of mechanical strength, more preferably 1.5, still more preferably 1.2, and particularly preferably 1.

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

  The lower limit of the plane orientation degree ΔP of the base film is preferably 0.08, more preferably 0.09, and still more preferably 0.1. If the lower limit is 0.08 or more, it is possible not only to eliminate rainbow marks more effectively, but also to reduce thickness unevenness of the film. The upper limit of the plane orientation degree ΔP of the base film is preferably 0.15, more preferably 0.14, and still more preferably 0.13. Refractive index anisotropy can be kept higher as the upper limit is 0.15 or less.

  The substrate film is preferably uniaxially oriented in order to impart refractive index anisotropy. As an orientation method, it can carry out by the usual method according to each resin. For example, in the case of extruding a molten resin in the form of a sheet on a cooling roll, a method of orienting the cooling roll by setting it at a speed equal to or higher than the speed of the extruded resin, heating an unstretched film melted and extruded. The method of stretching and orienting in the longitudinal direction with the group of rolls, and the method of heating and stretching the molten and extruded unstretched film in the tenter and stretching and orienting in the transverse direction or in the oblique direction may be mentioned.

  Among these, as a method for orienting the base film, there is a method of stretching and orienting the unstretched film which has been melted and extruded in the longitudinal direction with a heated roll group, and the unstretched film which has been melted and extruded. Preferred is a method of heating in a tenter and stretching in a lateral direction or an oblique direction for orientation. 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 lateral 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 orienting in the longitudinal direction, it is weak before stretching in the longitudinal direction (about 2.2 times or less to increase mechanical strength in the direction perpendicular to the orientation direction or adjust shrinkage characteristics. ) After stretching in the longitudinal direction, or after stretching in the longitudinal direction, weak (about 1.5 times or less) transverse stretching may be added. Similarly, even in the case of transverse orientation, it is weak before stretching in the transverse direction (about 2.2 times) in order to increase the mechanical strength in the direction perpendicular to the orientation direction or to adjust the shrinkage characteristics. The following longitudinal stretching may be added, or a weak (about 1.5 times or less) longitudinal stretching may be added after the transverse stretching. In order to further increase the orientation in the orientation direction, the film may be slightly shrunk in the longitudinal direction during or after the transverse stretching. The width after contraction is preferably 0.7 to 0.995 times, more preferably 0.8 to 0.99 times, and particularly preferably 0.9 to 0.98 times the width at the time of drawing. 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 temperature at the time of stretching (and the temperature of the preheating) is preferably 80 to 150 ° C. in both the longitudinal direction and the transverse direction. Moreover, after extending | stretching, in order to ensure the heat resistance of a base film, it is preferable to heat-set at high temperature from the heating temperature at the time of extending | stretching. As a heat setting temperature, 150-250 degreeC is preferable, More preferably, it is 170-245 degreeC.

  The base film desirably 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, further 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 make the light transmittance at a wavelength of 380 nm of the base film 20% or less, it is desirable to appropriately adjust the type, concentration, and thickness of the base film of the ultraviolet absorber blended in the base film. As a ultraviolet absorber used by this invention, an organic type ultraviolet absorber and an inorganic type ultraviolet absorber are mentioned. From the viewpoint of transparency, organic UV absorbers are preferred. Examples of the organic ultraviolet absorber include benzotriazole type, benzophenone type, cyclic imino ester type and the like, and combinations thereof, but there is no particular limitation as long as it is within the above-mentioned range of light transmittance. From the viewpoint of durability, benzotriazoles and cyclic imino esters are particularly preferred. When two or more types of ultraviolet absorbers are used in combination, ultraviolet rays of different wavelengths can be absorbed simultaneously, so that the ultraviolet absorption effect can be further improved.

It is also preferable to add various additives to the base film, as long as the effects of the present invention are not impaired, in addition to the ultraviolet light absorber. Additives include, for example, inorganic particles, heat resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, light stabilizers, flame retardants, thermal stabilizers, antioxidants, antigelling agents And surfactants. These additives can be used alone or in combination of two or more.
Moreover, in order to exhibit high transparency, it is also preferable not to contain particle | grains in a base film substantially. The phrase "does not substantially contain particles" means, for example, in the case of inorganic particles, 50 ppm or less, preferably 10 ppm or less, particularly preferably the detection limit or less, when the inorganic element in the substrate film is quantified by fluorescent X-ray analysis. Mean the content of

(Surface irregularities)
In the present invention, an uneven surface is provided on at least one side of the substrate film. The uneven surface may be provided on only one side of the substrate film, or may be provided on both sides. In addition, the base film which has an uneven surface may be called the roughened base film.

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

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

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

  The lower limit of the maximum height (Ry) of the rough surface of the roughened base film is preferably 2.0 μm, more preferably 3.0 μm, still more preferably 4.0 μm, and particularly preferably 4.5 μm. And most preferably 5.0 μm. The upper limit of the Ry is preferably 20 μm, more preferably 17 μm, still 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. is there. The upper limit of the Rp is preferably 15 μm, more preferably 12 μm, still more preferably 10 μm, and particularly preferably 8 μm.

  The lower limit of the maximum valley depth (Rv) 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. It is. The upper limit of the Rv is preferably 15 μm, more preferably 12 μm, still 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 limit, rainbow marks can be eliminated more effectively.
When the values of Ra, Rq, Rz, Ry, Rp, and Rv are the upper limit or more, the productivity is excellent.
Ra, Rq, Rz, Ry, Rp, and Rv are calculated from the roughness curve measured using a contact-type roughness meter in accordance with JIS B0601-1994 or JIS B0601-2001.

  By providing unevenness (roughening) on the surface of the substrate film, a retardation difference is provided in a very small area, and although coloring (rainbow spots) due to retardation in each area is made, the coloring is visually obscured be able to. The retardation difference ΔRe can be expressed 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, and most preferably 100 nm. Rainbow spots can be eliminated more effectively if the lower limit is 30 nm or more. The upper limit of ΔRe is preferably 1500 nm, more preferably 1000 nm, still more preferably 800 nm, particularly preferably 500 nm, and most preferably 300 nm. When the upper limit is 1,500 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. It 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, and most preferably 300 μm. It is. When the upper limit is 500 μm or less, it is possible to prevent the coloring or flickering due to the retardation of each of the minute regions.
Sm is calculated from a roughness curve measured using a contact-type roughness meter in accordance with JIS B0601-1994.

The base film may be thinner than the original thickness by providing the unevenness and roughening. The lower limit of the thickness of the roughened substrate film is preferably 10 μm, more preferably 15 μm, still more preferably 20 μm, particularly preferably 25 μm, and most preferably 30 μm. The intensity | strength as a protective film can fully be ensured as the said minimum is 10 micrometers or more. The upper limit of the thickness of the roughened substrate film is preferably 150 μm, more preferably 120 μm, still more preferably 100 μm, particularly preferably 90 μm, and most preferably 80 μm. The upper limit of 150 μm or less is suitable for thinning.
The roughened base film is embedded by embedding the roughened base film in an epoxy resin, and cutting a section of the cross section for microscopic observation, and the uneven surface is based on the center of the convex portion and the concave portion of the field of view The thickness of 10 points is measured at equal intervals, and it is calculated as the average value.

  The lower limit of the in-plane retardation (Re) of the roughened substrate film is preferably 2000 nm, more preferably 2500 nm, still more preferably 3000 nm, particularly preferably 3500 nm, and most preferably 4000 nm. is there. Rainbow spots can be eliminated more effectively if the lower limit is 2000 nm or more. The upper limit of the in-plane retardation (Re) of the roughened base film is preferably 30000 nm, more preferably 20000 nm, still more preferably 15000 nm, still more preferably 12000 nm, particularly preferably 10000 nm. More preferably, it is 9000 nm, most preferably 8000 nm, and most preferably 7500 nm. When the upper limit is 30000 nm or less, it is suitable for thinning.

There are no particular limitations on the method for providing the surface asperity, and there may be mentioned conventionally known methods of surface roughening. For example, sand blasting treatment, sand paper or file, treatment with grindstone etc., treatment with sander (orbital sander, random sander, delta sander, belt sander, disc sander, roll sander etc), treatment with metal brush etc, chemical etching, mold And molding by pressing at Among these, sand blast treatment, treatment with a sander, and chemical etching are preferable.
The sandblasting process may be, for example, a method of supplying a roll-like base film to a centrifugal blast machine and projecting an abrasive 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 rotary blade, and the like. Moreover, a sandblasting process may be the method of affixing a base film to a glass plate, setting to air blast, and spraying an abrasives on a base film surface. In this case, the roughness can be adjusted by the type of abrasive, the size of the abrasive, the blowing pressure, the processing time, and the like.
The processing by the sander is, for example, a method of guiding a roll-like base film to a conveyance device having a roll of sanding paper attached to the roll surface of a part of the film conveyance roll (roll sander). Good. In this case, the roughness can be adjusted by the type of sanding paper, the number of revolutions of the roll sander, the transport speed of the film, and the like. Also, the processing direction can be adjusted by the holding angle between the roll sander and the film, the number of rotations of the roll sander, the transport speed of the film, and the like.
In the sander processing, a urethane foam is attached to a glass plate, and a base film is further attached thereon, and the base film surface is vertically, horizontally, and diagonally (45 degrees, 135 degrees) in a total of four directions using a sander. It may be a method of processing from. The roughness can be adjusted depending on the type of sanding disc, processing time, etc.
In the sander treatment and sandblast treatment, the treated surface may be further polished with sand paper or the like in order to remove local protrusions.
The chemical etching may be a method in which the film is dipped in an acid or alkaline solution and washed with water, and then the masking film is peeled off and dried. The roughness can be adjusted by the immersion time or the like. Although chemical etching is basically double-sided processing, in the case of processing only one side, for example, a masking film is attached to one side of the base film.

(Optical isotropic layer)
It is preferable that the optically isotropic layer is 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 which can not be detected optically, preferably 100 nm or less, more preferably 50 nm or less, and particularly preferably 20 nm or less. If the easily bonding layer satisfies the range of the refractive index of the following optically isotropic layer, the easily bonding layer and the optically isotropic layer provided thereon are regarded as one optically isotropic layer. be able to. In addition, if the easily bonding layer has a sufficient thickness as an optically isotropic layer, the easily bonding layer may be regarded as an optically isotropic layer. By providing the optically isotropic layer, irregular reflection due to the unevenness of the surface of the base film can be reduced, and transparency can be ensured. In addition, the preferable refractive index of the easily bonding layer is the same as the range of the preferable refractive index of the following optical isotropic layer, and the adjustment method of 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, still more preferably Bfny-0.1, still more preferably Bfny-0.08, 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, still more preferably Bfnx + 0.1, still more preferably Bfnx + 0.08, particularly preferably It is Bfnx, most preferably Bfnx-0.02.
By setting the above-mentioned range, it is possible to maintain the contrast or the sharpness of the image and to suppress the phenomenon that the screen becomes whitish when strong external light is received.

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

The composition of the optically isotropic layer is not particularly limited, but 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, in the case of PMMA (polymethyl methacrylate), the refractive index is generally about 1.49. Acrylic pressure sensitive adhesives often introduce long chain or branched alkyl groups, and the refractive index is further lowered. In order to increase the refractive index, it is effective to copolymerize an acrylic monomer having an aromatic group or to copolymerize styrene.
Introduction of sulfur, bromine, fluorene group or the like into a polymer or resin is also a preferable method for raising the refractive index, and an acrylic copolymerized with a monomer containing these, a fluorene group-containing polyester, a fluorene group-containing polycarbonate, A thioepoxy resin is preferable as the high refractive index resin.

Further, addition of high refractive fine particles in a polymer or resin is also a suitable method of adjusting the refractive index.
The refractive index of the high refractive fine particles is preferably 1.60 to 2.74. Examples of the high refractive particles include fine particles of TiO ₂ , ZrO ₂ , CeO ₂ , Al ₂ O ₃ , BaTiO ₃ , Nb ₂ O ₅ , and SnO ₂ . The high refractive fine particles preferably have an average primary particle diameter of 3 nm to 100 nm as measured by TEM (transmission electron microscopy). These high refractive particles may be used alone or in combination of two or more.

  The optically isotropic layer is preferably crosslinked and cured. The curing method is not particularly limited, and thermal curing, radiation curing such as ultraviolet light, electron beam and the like are preferable. Examples of the crosslinking agent for curing include isocyanate compounds, epoxy compounds, carbodiimides, oxazoline compounds, amino resins such as melamine, polyfunctional acrylates, and the like.

  The optically isotropic layer is formed by applying a coating agent comprising the above components to the irregular surface of the substrate film, transferring an optically isotropic layer prepared by applying to a release film to the irregular surface of the substrate film, or the like The optically isotropic layer provided on the film of (1) can be laminated by a method such as bonding to the uneven surface of the base film. In this case, the coating agent is preferably dissolved or diluted with a solvent to have a viscosity that facilitates coating. The coating agent may be a non-solvent as long as it is a radiation curing type coating agent such as acrylic.

  For example, acrylic or other radiation curing type coating agents usually contain a photopolymerizable compound.

  As a photopolymerizable compound, a photopolymerizable monomer, a photopolymerizable oligomer, and a photopolymerizable polymer are mentioned, These can be adjusted suitably and can be used. As the photopolymerizable compound, a combination of a photopolymerizable monomer and a photopolymerizable oligomer or a photopolymerizable polymer is preferable.

Photopolymerizable Monomer The photopolymerizable monomer is one having a weight average molecular weight of less than 1000. As the photopolymerizable monomer, a polyfunctional monomer having two or more (that is, bifunctional) photopolymerizable functional groups is preferable. In the present specification, the "weight average molecular weight" is a value obtained by dissolving in a solvent such as THF and the like, and converting to polystyrene by a gel permeation chromatography (GPC) method known to date.

  Examples of the polyfunctional monomer include tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and 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, iso Anuric acid tri (meth) acrylate, isocyanuric acid di (meth) acrylate, polyester tri (meth) acrylate, polyester di (meth) acrylate, bisphenol di (meth) acrylate, diglycerin tetra (meth) acrylate, adamantyl di (meth) Acrylate, isoboronyl di (meth) acrylate, dicyclopentadi (meth) acrylate, tricyclodecane di (meth) acrylate, and those obtained by modifying these with PO, EO or the like.

  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 having high hardness.

Photopolymerizable Oligomer The photopolymerizable oligomer is one having a weight average molecular weight of 1,000 or more and less than 10,000. As a photopolymerizable oligomer, a bifunctional or higher polyfunctional oligomer is preferable. As a polyfunctional oligomer, polyester (meth) acrylate, urethane (meth) acrylate, polyester-urethane (meth) acrylate, polyether (meth) acrylate, polyol (meth) acrylate, melamine (meth) acrylate, isocyanurate (meth) Acrylate, epoxy (meth) acrylate, etc. are mentioned.

Photopolymerizable Polymer The photopolymerizable polymer has a weight average molecular weight of 10000 or more, and the weight average molecular weight is preferably 10000 or more and 80000 or less, and more preferably 10000 or more and 40000 or less. When the weight average molecular weight exceeds 80000, the coating suitability is lowered because the viscosity is high, and the appearance of the obtained laminated film may be deteriorated. As the photopolymerizable polymer, a bifunctional or higher polyfunctional polymer is preferable. As a polyfunctional polymer, urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, epoxy (meth) acrylate etc. are mentioned.

  The coating agent may contain, in addition to the components described above, a polymerization initiator, a catalyst for a crosslinking agent, a polymerization inhibitor, an antioxidant, an ultraviolet light absorber, a leveling agent, a surfactant, and the like.

  In addition, the optical isotropic layer composition is extruded and laminated on the irregular surface of the substrate film, and the optical isotropic layer composition is melted and extruded between the irregular surface of the substrate film and another film. And laminating are also preferable.

  The optically isotropic layer has the function of reducing irregular reflection of the uneven surface by being provided on the uneven surface, but may have other functions as well. The optically isotropic layer may have, for example, functions of a hard coat layer, an antireflective layer, an antiglare layer, an antistatic layer, and the like. The optically isotropic layer may be another film or sheet, a pressure-sensitive adhesive layer for bonding to a component of the apparatus, or an adhesive layer.

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, and most preferably 4 μm. The unevenness | corrugation of a base film can be planarized, a haze can be reduced as the said thickness is 0.5 micrometer or more, and 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, and most preferably 10 μm. It is suitable for thickness reduction that the said thickness is 30 micrometers or less.
The thickness of the optically isotropic layer is a 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, still more preferably 10 nm, particularly preferably 5 nm, from the viewpoint of suppressing the occurrence of rainbow marks.

  The upper limit of the refractive index difference between the refractive index in the direction of the highest refractive index of the optically isotropic layer and the refractive index in the direction of the lowest refractive index is preferably 0.01 from the viewpoint of suppressing the occurrence of rainbow marks Preferably it is 0.007, more preferably 0.005, particularly preferably 0.003 and most preferably 0.002.

(Laminated film)
The lower limit of the thickness of the laminated film is preferably 12 μm, more preferably 15 μm, still 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 the handling of production or subsequent processing becomes easy.
The upper limit of the thickness of the laminated film is preferably 180 μm, more preferably 150 μm, still more preferably 120 μm, particularly preferably 100 μm, and most preferably 90 μm. When the upper limit is 180 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 under a microscope, measuring the thickness of 10 points at regular intervals, and calculating the average value thereof.

  In the laminated film, only one side of the substrate film may be an uneven surface, but when the ΔRe of the substrate film is relatively low or the roughness of the uneven surface is relatively small, etc., the rainbow is more effective. In order to suppress a spot, it is preferable to make both surfaces of a base film into an uneven surface, and to provide an optical isotropic layer 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 the reduction in contrast and the whitening of the screen when strong external light is received.

The laminated film of the present invention may have two or more base films having an irregular surface (rough surface), may have two or more optically isotropic layers, and may have an irregular surface (rough You may have films or layers other than the base film which has a planarizing surface, and an optical isotropic layer.
Examples of lamination include the following types 1 to 4 and the like.
(Type 1) base film (concave / convex surface) / optical isotropic layer (adhesive or pressure sensitive adhesive) / other film (type 2) base film (concave / convex surface) / optical isotropic layer (adhesive or pressure sensitive adhesive) / (Concave surface) base film (type 3) base film (concave surface) / optical isotropic layer (adhesive or pressure sensitive adhesive) / other film / optical isotropic layer (adhesive or pressure sensitive adhesive) / (concave or convex surface Surface) Base film (Type 4) Other film / Optical isotropic layer (adhesive or pressure sensitive adhesive) / (concave / convex surface) Base film (concave / convex surface) / Optical isotropic layer (adhesive or pressure sensitive adhesive) / others When the ΔBfNxy of the substrate film of 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 addition, in description of the use of the laminated film of the following this invention, etc., when calling it a laminated film, the structure of said type 1-4 shall also be included. In the case of type 2 to type 3, the slow axes of the two base films are preferably parallel or perpendicular to each other, and preferably parallel for ease of production. Here, “parallel or perpendicular” is acceptable from 0 degrees or 90 degrees to preferably ± 10 degrees, further ± 7 degrees, particularly ± 5 degrees.

  In the specification, when the term "pressure-sensitive adhesive" or "pressure-sensitive adhesive layer" is used, a target is coated with a coating agent for pressure-sensitive adhesive and crosslinked or dried, or a substrateless optical pressure-sensitive adhesive is transferred. Means

(Anti-reflection surface)
In the present invention, it is preferable that at least one surface of the laminated film is an antireflective surface with a moth-eye structure (or a fine uneven structure).
The moth-eye structure usually means a concavo-convex structure with an average period shorter than the visible light wavelength as seen on the surface of the eyelids. In the moth-eye structure, the reflection of the interface is effectively prevented by the pseudo refractive index changing continuously from the top (the apex of the convex portion) to the deepest portion (the bottom point of the recess) of the uneven structure. Can.
When a laminated film with both sides smooth is used for the surface of a display device, a show window, etc., external light such as lighting and scenery may be reflected, and it may be difficult to see the display contents and the displayed items inside. In the case of a laminated film in which the surface is an antireflective surface having a moth-eye structure, the reflectance of the film surface can be reduced, and these reflections can be suppressed to reduce glare.

  The antireflective surface (or the fine uneven structure surface) may be the surface of the substrate film surface or the surface of the optically isotropic layer, but a separate layer (antireflection layer or moth-eye layer) on the substrate film or the optically isotropic layer Or when providing a fine concavo-convex structure layer, it may be the surface of the layer.

  In the anti-reflection surface, the concavo-convex structure may be a convex structure in which a convex portion is present in a plane, a concave structure in which a concave portion is present in a plane, or a structure provided with both a concave portion and a convex portion. It may be a waved structure without a plane.

In the antireflection surface, the height of the unevenness is preferably 100 nm to 1000 nm, more preferably 120 nm to 700 nm, still more preferably 150 nm to 500 nm, and particularly preferably 150 nm to 350 nm.
In addition, the height of unevenness | corrugation means the distance of the average of the deepest part, and the average of the highest part. The height of the unevenness is measured, for example, by the following measurement method.
(Measuring method)
The laminated film was embedded and cured in liquid silicone for molding, cooled with liquid nitrogen, and the uneven surface was cut vertically with a microtome. The silicone was peeled off and observed from a diagonally upper upper side (about 30 to 60 degrees with respect to the normal direction of the concavo-convex surface) to the cut surface by a scanning electron microscope. From the observation image, those in which the cut surface reaches the top of the concavo-convex structure are straight lines connected as the longest part line, and those in which the cut surface reaches the deepest part of the concavo-convex structure are straight lines connected as the deepest part line . The longest part line and the deepest part line are visually adjusted to be parallel, the distance between the longest part line and the deepest part line is measured, and a correction corresponding to the angle viewed obliquely is added to the value. Do this at 10 points, and let the average be the height of the unevenness.

  In the antireflection surface, the average aspect ratio represented by the ratio of the height of the unevenness to the average period of the unevenness is preferably 0.5 to 3.0. The average aspect ratio is more preferably 1.0 or more, particularly preferably 1.5 or more.

In the anti-reflection surface, it is preferable that the unevenness be present at an average period of 50 nm or more and 400 nm or less at least in a predetermined direction. 70 nm or more is preferable, 100 nm or more is more preferable, 120 nm or more is especially preferable, and 150 nm or more is still more preferable. The average period is preferably 350 nm or less, more preferably 300 nm or less, and particularly preferably 270 nm or less. The asperities may be randomly arranged or regularly arranged.
Note that the distance between convex portions (or the distance between concave portions) from the highest peak (or deepest point) in the convex portion (or concave portion) to the highest peak (or deepest point) of the adjacent convex portions (or concave portions) is this average value As the average period.

As a method for producing an antireflective surface (or a fine uneven surface), typically, a method by nanoimprinting, a method of applying a composition for an antireflective layer containing fine particles and a binder resin, and the like can be mentioned.
First, the method by nanoimprinting will be described.
The method by nanoimprinting is usually a method of transferring the pattern of this mold to the surface using a mold (mold) corresponding to the fine relief structure.
More specifically, (a) a method of putting a curable resin composition containing a monomer, an oligomer, a resin, etc. in a mold, crosslinking or polymerizing and curing it, (b) putting a molten resin in the mold, or melting it The method of pressing a mold to the resin which is carried out, cooling and hardening it, the method of pressing the heated mold on resin, etc. are mentioned. Among these, the method (a) is preferred. Further, among the methods (a), a method of curing with ultraviolet light using a photocurable resin composition is preferable.

As a photopolymerizable compound used for a photocurable resin composition, a photopolymerizable monomer, a photopolymerizable oligomer, and a photopolymerizable polymer are mentioned, These can be adjusted suitably and can be used.
As a photopolymerizable compound, various things, such as an acryl type, an epoxy resin type, a thio epoxy resin type, are used, and what is marketed as resin for nanoimprints can also be used suitably.
As specific acrylic photopolymerizable compounds, those mentioned for the optical isotropic layer are preferably used.

  The photocurable resin composition contains a polymerization initiator, a mold release agent, fine particles, a solvent, a binder resin, an antioxidant, an ultraviolet light absorber, a light stabilizer, an antifoamer, a lubricant, a leveling agent, etc. Can.

  Examples of the polymerization initiator include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides and the like. The polymerization initiator is preferably added in an amount of 0.3 to 5% by mass in the photocurable resin composition.

  As a mold release agent, surfactant of a silicone type and a fluorine type is preferable. The release agent is preferably added in an amount of 0.3 to 2% by mass in the photocurable resin composition.

  The viscosity of the photocurable resin composition at 24 ° C. is preferably 3 to 1000 mPa · s in order to accurately reproduce the pattern following the uneven surface of the mold.

As fine particles, oxide fine particles (for example, SiO ₂ fine particles, Al ₂ O ₃ fine particles, ZrO ₂ fine particles, TiO ₂ fine particles) are mentioned as preferable examples, and improvement of the hardness and toughness of the antireflection layer, adjustment of refractive index And so on. The particles may be surface treated.

  The average particle size of the microparticles is preferably 1 to 20 nm. The fine particles are preferably added in an amount of 5 to 30% by mass in the photocurable resin composition.

The refractive index of the antireflective layer (the moth-eye layer or the fine uneven structure layer) is different from the refractive index of the optical isotropic layer when provided on the optical isotropic layer surface, and the surface of the base film when provided on the substrate film surface. The difference with the inner average refractive index is preferably 0.2 or less, more preferably 0.15 or less, and particularly preferably 0.12 or less.
In addition, the refractive index of a reflection prevention layer is a value measured on the conditions of wavelength 589 nm.

As a method of transferring the pattern of the mold to the surface, for example, the following method is appropriately adopted.
After coating the photocurable resin composition on an object (substrate film, optically isotropic layer, etc.), the solvent is removed if necessary, the mold is superposed, and ultraviolet rays are irradiated to cure.
-After coating the photocurable resin composition on the mold, the solvent is removed if necessary, and the mold is superposed on a target (substrate film, optically isotropic layer, etc.) and irradiated with ultraviolet light to be cured.
-A photocurable resin composition is injected between a mold and a target (substrate film, optically isotropic layer, etc.), and is irradiated with ultraviolet rays to be cured.
When the mold is in the form of a roll, continuous production can also be performed on a long film.
The same method can be employed when the surface of the optically isotropic layer is a reflection preventing surface.

Next, a method of applying the composition for an antireflection layer containing fine particles and a binder resin will be described.
As the fine particles, particles having an average primary particle size of 100 to 300 nm are preferable, particles having an average primary particle size of 120 to 270 nm are more preferable, and particles having an average primary particle size of 150 to 250 nm are particularly preferable.
In the specification, “average primary particle size” refers to 50% particle size of volume accumulation. More specifically, 200 primary particles of the particles are observed at an appropriate magnification (about 5000 times) by SEM (scanning electron microscope) observation, each diameter is measured to calculate its volume, and its volume accumulation The 50% particle size of is taken as the average primary particle size.

0.1 to 10% is preferable and 0.1 to 5% of the dispersion degree (CV value) of the primary particle diameter of microparticles | fine-particles is more preferable. The CV value is a value calculated by the following equation.
CV value = ([standard deviation of average primary particle size] / [average particle size]) × 100

  Examples of the fine particles include metal oxide fine particles and resin fine particles. Examples of metal oxide particles include silica particles, titanium oxide particles, and alumina particles. Examples of the resin fine particles include acrylic fine particles, polystyrene fine particles, and melamine fine particles. The fine particles are preferably spherical in order to obtain a uniform fine uneven structure. The metal oxide fine particles are preferably surface-treated with a silane compound or the like.

  20-90 mass% is preferable in a reflection prevention layer, and, as for content of microparticles | fine-particles, 30-80 mass% is more preferable. Although depending on the specific gravity of the fine particles, when the content of the fine particles is too small, the fine particles may be buried in the binder resin and a favorable uneven structure may not be obtained. When the content of the fine particles is too large, the bonding force of the fine particles with the binder resin becomes weak, the fine particles may be separated by a slight stimulation, and may be scratched or difficult to handle.

  As a binder resin, the photopolymerizable compound mentioned by the optical isotropic layer is used preferably. In this case, the antireflective layer can be formed by curing the photopolymerizable compound.

  The composition for forming an antireflective layer may further contain a solvent, a polymerization initiator, a dispersant for particles, a leveling agent, an antifouling agent, and the like.

(Hard coat layer)
The hard coat layer may be provided on the substrate film and / or the optically isotropic layer directly or through another film or layer (for example, an easy adhesion layer). The hard coat layer may be a layer inside the antireflective layer.
The hard coat layer may further have other functions and may be an optically isotropic layer.
The hard coat layer preferably has a pencil hardness of H or more, more preferably 2H or more. The hard coat layer can be provided, for example, by applying and curing a composition solution of a thermosetting resin or a radiation curable resin.

  As a thermosetting resin, an acrylic resin, a urethane resin, a phenol resin, a urea melamine resin, an epoxy resin, an unsaturated polyester resin, a silicone resin, a combination thereof, and the like can be mentioned. In the thermosetting resin composition, a curing agent is added to these curable resins as needed.

  The radiation curable resin is preferably a compound having a radiation curable functional group, and as the radiation curable functional group, an ethylenic unsaturated bond group such as (meth) acryloyl group, vinyl group, allyl group, epoxy group And oxetanyl groups. Among these, as the ionizing radiation-curable compound, a compound having an ethylenically unsaturated bond group is preferable, and a compound having two or more ethylenically unsaturated bond groups is more preferable, and in particular, two ethylenically unsaturated bond groups The polyfunctional (meth) acrylate compound having the above is more preferable. The polyfunctional (meth) acrylate compound may be a monomer, an oligomer or a polymer.

As specific examples of these, those mentioned as the binder resin of the antireflection layer are used.
In order to achieve the hardness as a hard coat, the compound having a radiation curable functional group preferably contains 50% by mass or more of a bifunctional or higher monomer, and more preferably 70% by mass or more. Furthermore, in the compound having a radiation curable functional group, the content of the trifunctional or higher monomer is preferably 50% by mass or more, and particularly preferably 70% by mass or more.
The compound which has the said radiation curable functional group can be used 1 type or in combination of 2 or more types.

  The thickness of the hard coat layer is preferably in the range of 0.1 to 100 μm, and more preferably in the range of 0.8 to 20 μm.

The refractive index of the hard coat layer is more preferably 1.45 to 1.70, and still more preferably 1.50 to 1.60.
The refractive index of the hard coat layer is a value measured under the condition of wavelength 589 nm.

In order to adjust the refractive index of the hard coat layer, there are mentioned a method of adjusting the refractive index of the resin, and a method of adjusting the refractive index of the particles when adding the particles.
Examples of the particles include those exemplified as particles of the optical isotropic layer or the antireflective layer.

(Antistatic layer)
It is also a preferable form to separately provide an antistatic layer. The antistatic layer is formed between the substrate film and the antireflective layer, between the optically isotropic layer and the antireflective layer, between the substrate film and the hard coat layer, between the optically isotropic layer and the hard coat layer. It is preferable to provide on the surface etc. in which the reflection preventing surface of laminated | multilayer film is not formed. The antistatic layer preferably comprises an antistatic agent and a binder resin.
Examples of antistatic agents include quaternary ammonium salts, conductive polymers such as polyaniline and polythiophene, needle-like metal fillers, conductive high refractive index fine particles such as tin-doped indium oxide fine particles, and antimony-doped tin oxide fine particles, and combinations thereof Be
As the binder resin, polyester, polyurethane, polyamide, acrylic or the like is used.
In addition, an antistatic agent may be added to a hard-coat layer, and a hard-coat layer may function as an antistatic layer. As the antistatic agent to be added to the hard coat layer, conventionally known ones can be used. For example, cationic antistatic agents such as quaternary ammonium salt, fine particles such as tin-doped indium oxide (ITO), conductive polymer Etc. can be used. It is preferable that content of the said antistatic agent is 1-30 mass% with respect to the total mass of the total solid of a hard-coat layer.

  The laminated film of the present invention may further have various functional layers in accordance with each application. As various functional layers, an antiglare layer, other antireflective layers (for example, a combination of a high refractive index layer and a low refractive index layer), a low reflective layer, a conductive layer, a colored layer, an ultraviolet absorbing layer, an antifouling layer And an adhesive layer.

(Use of laminated film)
The laminated film of the present invention is not only an optical polarizer film such as a polarizer protective film or a depolarizing film, a transparent conductive substrate film such as a touch panel, an anti-scattering film, a surface design-imparting film, etc. It can be used in various fields such as films and films for decoration.

First, the polarizing plate which used the said laminated film as a polarizer protective film which is a typical application example is demonstrated.
(Lamination of polarizer and laminated film)
As a polarizer used for a polarizing plate, for example, one obtained by adsorbing iodine or an organic dichroic dye to uniaxially stretched polyvinyl alcohol (PVA), one obtained by aligning a liquid crystal compound and an organic dichroic dye Alternatively, a liquid crystalline polarizer comprising a liquid crystalline dichroic dye, a wire grid type, or the like can be used without particular limitation.

  In the case of a film-like polarizer in which iodine or an organic dichroic dye is adsorbed to uniaxially stretched polyvinyl alcohol (PVA), the laminated film of the present invention is laminated on at least one side of the polarizer to make a polarizing plate be able to. At the time of lamination, an adhesive such as PVA-based or UV-curable or an adhesive can be used. In addition, the uneven surface of the base film and the polarizer may be bonded together with an adhesive or a pressure-sensitive adhesive having a property corresponding to the optical isotropic layer in the present invention. In this case, the base film and the adhesive or the adhesive form a laminated film having the base film and the optically isotropic layer in the present invention. The thickness of the polarizer of this type is preferably 5 to 50 μm, more preferably 10 to 30 μm, and particularly preferably 12 to 25 μm. The thickness of the adhesive or pressure-sensitive adhesive is preferably 1 to 10 μm, more preferably 2 to 5 μm.

  In addition, a polarizer is also preferably used in which PVA is coated on an unstretched substrate such as PET or polypropylene and uniaxially stretched with the substrate to adsorb iodine or an organic dichroic dye. In the case of this polarizer, the polarizer surface (surface on which the substrate is not laminated) of the polarizer laminated on the substrate and the laminated film of the present invention are bonded with an adhesive or a pressure-sensitive adhesive, and then the polarizer is By peeling the base material used at the time of preparation, it can be set as a polarizing plate. Also in this case, the uneven surface of the base film and the polarizer may be bonded with an adhesive or a pressure-sensitive adhesive having a property corresponding to the optical isotropic layer in the present invention. The thickness of this type of polarizer is preferably 1 to 10 μm, more preferably 2 to 8 μm, and particularly preferably 3 to 6 μm. The thickness of the adhesive or pressure-sensitive adhesive is preferably 1 to 10 μm, more preferably 2 to 5 μm.

In the case of a liquid crystalline polarizer, the laminated film of the present invention is laminated with a polarizer having a liquid crystal compound and an organic dichroic dye oriented, or the laminated film of the present invention is liquid crystalline. After a coating solution containing a dichroic dye is applied, it is dried and cured by light or heat to laminate a polarizer, whereby a polarizing plate can be obtained. Examples of a method of orienting a liquid crystalline polarizer include a method of rubbing the surface of an object to be coated, a method of irradiating while applying polarized ultraviolet light and orienting and curing a liquid crystalline polarizer. The surface of the laminated film of the present invention may be directly rubbed to apply a coating solution, or the coating film may be directly applied to the laminated film and irradiated with polarized ultraviolet light. In addition, it is also preferable to provide an orientation layer on the laminated film of the present invention (that is, to laminate a liquid crystalline polarizer on the laminated film of the present invention via the orientation layer) before providing a liquid crystalline polarizer. is there. As a method of providing an orientation layer,
· A method of applying polyvinyl alcohol and its derivative, polyimide and its derivative, acrylic resin, polysiloxane derivative and the like, rubbing the surface thereof to form an alignment layer (rubbing alignment layer),
・ A method of applying a coating solution containing a polymer or monomer having a photoreactive group such as cinnamoyl group and chalcone group and a solvent, and performing alignment curing by irradiating polarized ultraviolet rays to form an alignment layer (photo alignment layer) Can be mentioned.
In addition, a rubbing alignment layer having characteristics corresponding to the optical isotropic layer in the present invention may be provided on the uneven surface of the base film, and the base film and the rubbing alignment layer may be used as the laminated film of the present invention.

A liquid crystalline polarizer is provided on a film having releasability according to the above method, the liquid crystal polarizer surface and the laminated film of the present invention are bonded with an adhesive or a pressure sensitive adhesive, and then releasability is exhibited. By peeling the film, a polarizing plate can be obtained. Also in this case, the uneven surface of the base film and the polarizer may be bonded together with an adhesive or pressure-sensitive adhesive having a property corresponding to the optical isotropic layer in the present invention.
The thickness of the liquid crystalline polarizer is preferably 0.1 to 7 μm, more preferably 0.3 to 5 μm, and particularly preferably 0.5 to 3 μm. The thickness of the adhesive or pressure-sensitive adhesive is preferably 1 to 10 μm, more preferably 2 to 5 μm.

  In the case of the wire grid system, fine conductive wires may be provided on the laminated film of the present invention. When a fine groove is required to provide a fine conductive wire, a layer for providing a groove may be separately provided, or a layer for providing a groove may be an optical isotropic layer in the present invention.

  The angle between the transmission axis of the polarizer and the slow axis of the laminated film is not particularly limited, but the laminated film is used as a polarizer protective film of a polarizing plate for converting ordinary transmitted light into linearly polarized light. Are preferably parallel or perpendicular. “Parallel or vertical” is acceptable from 0 ° or 90 ° to preferably ± 10 °, even ± 7 °, in particular ± 5 °.

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

  In the above, the surface on which the polarizer of the laminated film of the present invention is laminated may be either a substrate film surface or an optically isotropic layer surface. When the optically isotropic layer is a layer having a function of a polarizing plate surface such as a hard coat layer or an antireflective layer, it is preferable to provide a polarizer on the base film surface.

  The other surface of the polarizer of the polarizing plate obtained in this manner can take various forms depending on the purpose. As a layer laminated on the other side of the polarizer, for example, glass, a polarizer protective film without birefringence, an optical compensation film, a λ / 4 retardation film, a λ / 2 retardation film, retardation (optical Compensation) A coating layer, a protective coating layer, a thing without these protective layers, an adhesive layer etc. are mentioned. The layer laminated on the other side of the polarizer may be the laminated film of the present invention.

As a polarizer protective film without birefringence, a TAC film, an acrylic film, a cyclic olefin film, a polypropylene film and the like can be mentioned.
Examples of the optical compensation film include those having positive or negative A plate, C plate characteristics, etc., and those obtained by stretching the above film or polycarbonate film, and coated with a rod-like liquid crystal compound or discotic liquid crystal compound on the surface such as TAC film. And the like. These are suitably selected according to the characteristic of the liquid crystal cell as a polarizing plate of a liquid crystal display device.
The λ / 4 retardation film and the λ / 2 retardation film can be obtained by the same method as the optical compensation film. These are used, for example, for a circularly polarizing plate, and are suitable for an antireflective film such as an organic EL display device. The thickness thereof is preferably 10 to 80 μm, and more preferably 20 to 60 μm.

As an application of thickness reduction of an image display apparatus, a phase difference (optical compensation) coating layer, a protective coating layer, a thing without these protective layers, an adhesive layer etc. are mentioned.
The retardation (optical compensation) coating layer can be formed by a method of coating a liquid crystal compound on a polarizer, a method of separately providing a retardation layer on a releasable film, and transferring the same. In particular, in the case of thinning the polarizing plate, it is suitably combined with a substrate liquid crystalline polarizer or a polarizer for transferring a polarizer laminated on a substrate.

(Display device)

  The above-mentioned polarizing plate is suitably used on either side of the light source side polarizing plate or the viewing side polarizing plate of the display device, and it is also a preferable embodiment to use both of them. In addition, it is preferable to use the laminated | multilayer film of this invention as a polarizer protective film on the opposite surface to a display cell.

  Backlights of liquid crystal display devices include blue light emitting diode and yellow fluorescent light source, blue-green red light emitting diode light source, blue light emitting diode, green fluorescent light and red fluorescent light source, wavelength conversion light source by quantum dots, semiconductor A laser light source, a cold cathode tube, etc. can be used without particular limitation.

  The polarizing plate using the laminated film of the present invention as a polarizer protective film is reduced to a level at which iridescence can not be recognized even in a liquid crystal display device having a light source having a sharp emission peak, and A combination with a light source with a narrow half-width is a more preferable form. The half width of the light emission peak having the narrowest half width is preferably 25 nm or less, more preferably 20 nm or less, still more preferably 15 nm or less, particularly preferably 10 nm or less. The lower limit of the half bandwidth is 0.5 nm in terms of realistic values or resolution of the measuring instrument. Specifically, a QD (quantum dot) light source and a light source using a KSF phosphor for the red region are mentioned as preferable light sources, and the most preferable light source is one using a KSF phosphor.

  When the laminated film of the present invention is used as a polarizer protective film in accordance with recent thinning, the thickness of the laminated film of the present invention is also preferably 12 to 60 μm, more preferably 15 to 50 μm. In the case of such a thin image display device, the light source is preferably a light source of blue light emitting diode and yellow phosphor, a light source using a KSF phosphor, a QD light source or the like.

  Moreover, the laminated film of this invention can be used suitably also as a polarizer protective film of the circularly-polarizing plate for reflection prevention of an organic electroluminescence display.

Hereinafter, the present invention will be more specifically described with reference to examples. The present invention is not limited to the following examples, and can be implemented with appropriate modifications as long as they are compatible with the spirit of the present invention. These are all included in the technical scope of the present invention.
The evaluation method of the physical property in an Example is as follows.

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

(2) Thickness d of original film
The thickness at five points was measured using an electric micrometer (Filt Luff, Millitron 1245D), and the average value was determined.

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

(4) Nz coefficient The value obtained by | Bfnx-Bfnz | / | Bfnx-Bfny |

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

(6) Thickness direction retardation (Rth)
The thickness direction retardation is obtained by multiplying the film thickness d by two birefringence ΔBfNxz (= | Bfnx-Bfnz |) and ΔBfNyz (= | Bfny-Bfnz |) as viewed from the cross section in the film thickness direction. It is a parameter which shows the average of the retardation obtained. Find Bfnx, Bfny, Bfnz and film thickness d (nm) by the same method as above, calculate the average value of (ΔBfNxz × d) and (ΔBfNyz × d), and calculate the thickness direction retardation (Rth) Obtained: Rth = (ΔBfNxz × d + ΔBfNyz × d) / 2.

(7) Surface roughness of the uneven surface of the base film (Ra, Rq, Rz, Ry, Rp, Rv, Sm)
Each parameter of surface roughness was measured from a roughness curve measured using a contact roughness meter (Mitutoyo SJ-410, detector: 178-396-2, stylus: standard stylus 122 AC 731 (2 μm)). I asked. The setting was as follows.
Curve: R
Filter: GAUSS
λc: 0.8 mm
λs: 2.5 μm
Measurement length: 5 mm
Measurement speed: 0.5 mm / s
In addition, Rq was calculated | required based on JISB0601-2001 and others based on JISB0601-1994.

(8) Thickness of Optically Isotropic Layer The thickness of the roughened base film and laminated film is as follows: embedded each film in an epoxy resin, cut out a section of the cross section, and observe with a microscope to obtain 10 points at equal intervals. The thickness was measured and taken as the average value. In addition, when the interface was hard to see, a polarization microscope was used. Moreover, 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 the optically anisotropic layer on the uneven surface of the mold release film, the thickness is about 20 μm, and the refractive index of the sample peeled from the mold release film It measured by carrying out similarly to the base film. It was confirmed that nx, ny and nz had the same value.

(10) Average Period of Irregularities of Moss Eye Layer From the image observed from the upper side of the irregular surface with a scanning electron microscope (SEM), randomly select 50 convex portions (the highest vertex) and 50 concave portions (the deepest point) and randomly approach each other The distance between the highest points (or the deepest points) was measured, and the average value was taken as the average period. In addition, when a convex part exists in a plane, when it has a recessed part in a plane, it was set as 100 points only at the highest point or only the deepest point.

(Production of easy adhesion layer components)
(Polymerization of polyester resin)
In a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial reflux condenser, 194.2 parts by mass of dimethyl terephthalate, 184.5 parts by mass of dimethyl isophthalate, 14.8 parts by mass of dimethyl-5-sodium sulfoisophthalate Then, 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 performed at a temperature of 160 ° C. to 220 ° C. for 4 hours. Then, the temperature was raised to 255 ° C., and the reaction system was gradually depressurized, and then reacted under a reduced pressure of 30 Pa for 1 hour and 30 minutes to obtain a copolyester resin. The resulting copolyester resin was pale yellow and transparent. The reduced viscosity of the copolyester resin was measured and found to be 0.70 dl / g. The glass transition temperature by DSC was 40.degree.

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

(Polymerization of block polyisocyanate type crosslinking agent used in easy adhesion layer)
100 parts by mass of polyisocyanate compound having isocyanurate structure (Duranate TPA, manufactured by Asahi Kasei Chemicals Corp.) having hexamethylene diisocyanate as a raw material in a flask equipped with a stirrer, thermometer, and reflux condenser, 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 maintained at 70 ° C. for 4 hours under a nitrogen atmosphere. Thereafter, the reaction solution temperature was lowered to 50 ° C., and 47 parts by mass of methyl ethyl ketoxime was dropped. The infrared spectrum of the reaction solution was measured to confirm that the absorption of the isocyanate group disappeared, and a block polyisocyanate water dispersion having a solid content of 75% by mass was obtained.

(Preparation of coating solution for easy adhesion layer)
The following coating agents were mixed to prepare a P1 coating solution.
Water 50.00 mass%
Isopropanol 33.00 mass%
Polyester water dispersion 12.00 mass%
Blocked isocyanate type crosslinking agent 0.80 mass%
Particles 1.40% by mass
(Silica sol with an average particle size of 100 nm, solid concentration 40% by mass)
Catalyst (Organotin-based compound solid concentration 14% by mass) 0.30% by mass
0.50 mass% of surfactant
(Silicone, solid content 10% by mass)

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

  After completion of the polycondensation reaction, filtration treatment is carried out with a Naslon (registered trademark) filter with a 95% cut diameter of 5 μm, extruded in a strand form from a nozzle, and cooling water subjected to filtration treatment (pore diameter: 1 μm or less) It was cooled, solidified, and cut into pellets. The intrinsic viscosity of the obtained polyethylene terephthalate resin (X) was 0.62 dl / g, and substantially no inert particles and internally precipitated particles were contained. (Hereafter, it is abbreviated as PET (X).)

(Production of original film A, B)
The PET (X) resin pellet containing no particles is supplied to an extruder as a raw material for a film, sheeted and extruded from a die, and then wound around a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method. It solidified by cooling and produced the unstretched film. Next, the P1 coating solution is applied to both sides of this unstretched PET film so that the coating amount after drying is 0.12 g / m ² by reverse roll method, and then it is directed to a dryer and dried at 80 ° C. for 20 seconds did.

The unstretched film on which this coated layer was formed was guided to a tenter stretching machine, and while holding the end of the film with a clip, it 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, the film is treated at a temperature of 225 ° C. for 30 seconds, and then both ends of the film cooled to 130 ° C. are cut with a shear blade and a tension of 0.5 kg / mm ² The ear portion was cut off with the above, and wound up to obtain an original film A having a film thickness of 80 μm.

  A film was produced in the same manner as in the raw film A except that the line speed after casting was increased to change the thickness of the unstretched film, and a raw film B having a different film thickness was obtained.

(Production of original film C)
An unstretched film (coated with an easily adhesive layer) prepared 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 having a peripheral speed difference The film was drawn by 2.0 times in the running direction, and then introduced into a hot air zone at a temperature of 135 ° C. by a method similar to that for the raw film A, and then stretched by 4.0 times in the width direction to obtain a raw film C.

(Raw film D)
An unstretched film (coated with an easily adhesive layer) prepared 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 having a peripheral speed difference After stretching 3.5 times in the running direction, the film was introduced into a hot air zone at a temperature of 135 ° C. in the same manner as in the raw film A and stretched 3.5 times in the width direction to obtain a raw film D.

(Production of surface roughened film)
Affix polyurethane foam to a glass plate and affix the periphery of the original film A with a double-sided tape on top of that, and use this hand-held belt sander (sanding belt # 320) to hold the original film surface vertically, horizontally or diagonally The surface roughened film A1 was obtained by processing from a total of 4 directions of 45 degrees and 135 degrees.
The periphery of the raw film A was attached to a glass plate with a double-sided tape, set in a dry sand blaster, and treated by blowing an abrasive (sand blast treatment) to obtain a surface roughened film A2.
A masking film made of polypropylene film is laminated on one side of the raw film A, dipped in a 38% aqueous potassium hydroxide solution (95 ° C.) (chemical etching), washed with water, peeled off and dried. The surface roughened film A4 was obtained.
The surface roughened films shown in Table 2 are obtained from the raw films A, B, C, and D by changing the conditions of the belt sander (type of the sanding belt, etc.) and the conditions of the sand blast (particle diameter of the abrasive). The
The # 320 sanding belt was used for the production of B1 and C1, and the # 180 sanding belt was used for the production of A3 and D1. Moreover, the abrasives of the sand blaster used a large thing in order of A5, A6, B2, and A2.
In the belt sander treatment and sand blast treatment, the treated surface was lightly polished with # 400 sandpaper to remove the influence of local protrusions.

(Manufacturing of optically isotropic layer laminated film)
(Preparation of coating agent for optically isotropic layer)
What was shown in Table 3 as a coating agent for optical isotropic layers was prepared.

  A surface of the surface roughening film A1 of 20 cm × 30 cm is coated with a four-fold diluted solution of the above-mentioned easy adhesion layer with a solution of water / isopropanol = 2/1 and dried, and the adhesion is about 30 nm A layer was provided. Furthermore, after coating agent a for optically isotropic layers with an applicator, it was made to harden | cure from a coated surface with a high pressure mercury lamp, and optically isotropic layer laminated film F1 was obtained.

  Optical isotropic layer laminated films F2 to F16 were obtained in the same manner as described above except that the type of the surface roughened film and / or the coating agent was changed. The optically isotropic layer laminated film F14 was provided with optically isotropic layers on both sides.

A solution of Byron (registered trademark) 200 (RV 200) (manufactured by Toyobo Co., Ltd.) in a 20% toluene / methyl ethyl ketone mixed solvent is applied to the uneven surface of a 20 cm × 30 cm roughened film B2 and then dried. Provided. The optically isotropic layer surfaces of the obtained two optically isotropic layer laminated films are overlapped, passed between rolls heated to 100 ° C., and passed between two rolls of the optically isotropic layer laminated film, and the optically isotropic layer laminated film I got F17. In addition, in the case of bonding, it bonded together so that the slow axis of roughening film B2 might become parallel. The refractive index of the Byron 200 is 1.55.
The configuration of each optically isotropic layer laminated film is shown in Table 4.

(Manufacture of laminated film (antireflection film))
The following were prepared as a composition for moth-eye layer.
(Composition for moth eye layer)
Polyethylene glycol # 1000 diacrylate 40 parts by mass Urethane prepolymer 50 parts by mass
(Reaction product of dipentaerythritol pentaacrylate and hexamethylene diisocyanate)
Irgacure 184 5 parts by mass

(Production of laminated film having moth-eye layer on optically isotropic layer surface)
Examples 1 to 13 and Comparative Examples 1 to 3
The composition for moth-eye layer was dropped on the center of the optically isotropic layer surface. Cover with a moth-eye layer mold [HT-AR-05A (Inox Co., average height 300 nm, peak-to-peak distance 290 nm)] to spread the moth-eye layer composition, irradiate with ultraviolet rays and cure, and then moth eye layer It formed, and laminated film MIF1c-MIF16c were obtained.
As a result of observation with a scanning electron microscope, a concavo-convex pattern was transferred. That is, the height of the unevenness of the surface of the moth eye layer was 300 nm, and the average period was 290 nm.

(Preparation of laminated film having moth-eye layer on base film)
Examples 14 to 26 and Comparative Examples 4 to 6
Pertron (trademark) A-2005 (made by Pelnox Co., Ltd.) was coated on the base film surface, and the ultraviolet-ray was irradiated and the hard-coat layer was provided. The thickness of the hard coat layer was 5 μm.
Furthermore, a moth-eye layer was formed on the hard coat layer in the same manner as in Example 1 to obtain laminated films MF1 b to MF16 b.

(Production of a laminated film in which the optically isotropic layer is a moth-eye layer)
Example 27
The coating agent e for the optical isotropic layer was dropped to the center of the uneven surface of the surface roughened film A1. Thereafter, in the same manner as in Example 1, a moth-eye structure was directly formed on the surface of the optically isotropic layer to obtain a laminated film MIFA 1 d.

(Evaluation of laminated film)
(Observation of rainbow blotches)
The laminated film is placed between two polarizing plates arranged in cross nicol so that the slow axis is 45 degrees to the transmission axis of the polarizing plate on the light source side, and transmitted light from the front about 60 cm away from the polarizing plate on the viewing side The condition of was observed, and the presence or absence of rainbow marks was evaluated according to the following criteria. In addition, the light source used the cold cathode tube.
○: Rainbow spots were not observed Δ: Slight rainbow spots were observed ×: Rainbow spots were observed

(Whitening)
The laminated film was irradiated with a halogen lamp from below, and the degree of whitening of the laminated film was observed from the direction of 45 degrees obliquely upward. In addition, the moth-eye layer surface was turned up.
◎: Almost no whitening was observed.
○: A slight whitening was observed, but the transparency was high.
Δ: Whitening was observed, and the transparency was somewhat inferior.
X: Whitening occurred and transparency was low.
In Examples 28 to 33, evaluation was performed using a polarizing plate.

(Anti-reflection evaluation)
The laminated film was placed on a landscape print, and the fluorescent lamp was illuminated from 45 degrees diagonally above, and observed from 45 degrees above the opposite side of the fluorescent lamp.
:: The reflection was effectively suppressed and the printed matter was clearly seen.
○: The reflection was suppressed and the printed matter was seen.
X: There was almost no effect of suppressing reflection.
In Examples 28 to 33, evaluation was performed using a polarizing plate.

(Manufacture of polarizing plate)
(Manufacture of polarizer)
A polyvinyl alcohol resin film having a degree of saponification of 99.9% was introduced into a roll having a peripheral speed difference, and uniaxial stretching was performed at 100 ° C. and tripled. The resulting stretched polyvinyl alcohol stretched film is dyed in a mixed aqueous solution of potassium iodide (0.3%) and iodine (0.05%) and then 1.8 in a 10% aqueous solution of boric acid at 72 ° C. It was uniaxially stretched to double. Thereafter, the resultant was washed with ion-exchanged water, further immersed in a 6% aqueous potassium iodide solution, removed with an air knife, and then dried at 45 ° C. to obtain a polarizer. The thickness of the polarizer was 18 μm.

(Preparation of TAC film laminated polarizer)
First, a polarizer and a triacetyl cellulose (TAC) film with a thickness of 60 μm coated with an ultraviolet-curable acrylic adhesive are prepared, and a polarizer is laminated thereon to irradiate a high pressure mercury lamp from the TAC surface. It was cured to obtain a TAC film laminated polarizer.

(Production of Polarizing Plate Using Laminated Films of Examples 1 to 27 and Comparative Examples 1 to 6)
A UV curable acrylic adhesive was applied by an applicator to the surface of the laminated film opposite to the surface on which the moth-eye layer was formed. The polarizer surface of the TAC film laminated polarizer cut into a size of 20 cm × 30 cm was superposed on this coated surface, and the high-pressure mercury lamp was irradiated from the laminated film side to be cured to obtain a polarizing plate. The transmission axis of the polarizer and the slow axis of the base film were parallel to each other.
About the polarizing plate using the laminated film of Example 4, 5, 17, and 18, the polarizing plate which is the same except that the transmission axis of the polarizer and the slow axis of the base film are perpendicular is also manufactured. did.

(Preparation of coating agent for pressure-sensitive adhesive used as optically isotropic layer)
What was shown in Table 5 was used as an adhesive.

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 An ethyl acetate solution (solid content concentration: 30% by mass) of a copolymer (Mw = 400,000) was obtained by reacting 0.25 parts by mass of bisisobutyronitrile in ethyl acetate.

Example 28
A moth-eye layer was provided on the smooth surface of a surface-roughened film A1 of 20 cm × 30 cm in the same manner as in Example 14. Moreover, after apply | coating the coating agent i for adhesives as an optical isotropic layer with an applicator to the uneven surface of surface roughening film A1, it was made to harden | cure with a high pressure mercury lamp from a coated surface, and the laminated film was obtained. The adhesive layer surface of the obtained laminated film and the polarizer surface of the TAC film laminated polarizer cut into 20 cm × 30 cm were bonded to each other to prepare a polarizing plate. The transmission axis of the polarizer and the slow axis of the surface roughened film (substrate film) were parallel to each other.

Example 29
Coating agent for pressure-sensitive adhesive as an optical isotropy layer on the rough surface (surface on which the moth-eye layer is not laminated) of the surface roughened film A1 having the moth-eye layer laminated, which was used for producing the polarizing plate of Example 28 Was coated with an applicator and dried at 100 ° C. to obtain a laminated film, in the same manner as in Example 28, to obtain a polarizing plate.

Examples 30-32
The coating agent b for the optical isotropic layer was applied to the irregular surface (the surface on which the moth-eye layer is not laminated) of the surface roughened film A1 having the moth-eye layer laminated, used in the production of the polarizing plate of Example 28 It coated with. The polarizer surface of the TAC film laminated polarizer cut into a size of 20 cm × 30 cm was superposed on this coated surface, and the surface roughened film A1 was irradiated with a high-pressure mercury lamp to be cured to obtain a polarizing plate.
In addition, a polarizing plate was obtained in the same manner as described above except that the coating agent for the optically isotropic layer was changed to e or f.

(Manufacture of a polarizing plate having a protective film only on one side)
(Manufacture of base laminate polarizer)
A 100 μm thick unstretched film is prepared using PET (X) as a thermoplastic resin substrate, and an aqueous solution of a polyvinyl alcohol having a degree of polymerization of 2400 and a degree of saponification of 99.9 mol% is coated on one side of this unstretched film. And it dried and formed the PVA layer and obtained the laminated body.
The obtained laminate was stretched and wound in the longitudinal direction twice at 120 ° C. between rolls different in peripheral speed.
Next, the obtained laminate is treated with a 4% aqueous boric acid solution for 30 seconds, and then dipped in a mixed aqueous solution of iodine (0.2%) and potassium iodide (1%) for 60 seconds to stain It was then treated with a mixed aqueous solution of potassium iodide (3%) and boric acid (3%) for 30 seconds.
Furthermore, the laminate obtained is uniaxially stretched in the longitudinal direction in a mixed aqueous solution of boric acid (4%) and potassium iodide (5%) at 72 ° C., and subsequently washed with a 4% aqueous solution of potassium iodide, After removing the aqueous solution with an air knife, it was dried in an oven at 80 ° C., and both ends were slit and wound up to obtain a base laminate 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. In addition, the thickness embedded the base material lamination | stacking polarizer in an epoxy resin, cut out the slice, observed and read it with the optical microscope.

Example 33
After bonding the adhesive layer surface of the laminate film used in the production of the polarizing plate of Example 29 to the polarizer surface of the substrate laminate polarizer, the substrate of the substrate laminate polarizer is peeled off, and the single-sided protective film polarizer I got A commercially available optical pressure-sensitive adhesive sheet was laminated on the polarizer surface of this polarizing plate. The transmission axis of the polarizer and the slow axis of the substrate film were parallel to each other.

Example 34
An ultraviolet-curable acrylic adhesive was applied to the surface of the optically isotropic layer of the laminated film MIF5c (Example 5) with an applicator. The polarizer surface of the substrate laminate polarizer is attached to this coated surface, and then light is irradiated from the laminate film side with a high pressure mercury lamp to peel off the substrate laminate polarizer to obtain a single-sided protective film polarizing plate The A commercially available optical pressure-sensitive adhesive sheet was laminated on the polarizer surface of this polarizing plate. The transmission axis of the polarizer and the slow axis of the substrate film were parallel to each other.

Example 35
A single-sided protective film polarizing plate was obtained in the same manner as in Example 33 except that an ultraviolet-curable acrylic adhesive was provided on the surface of the surface-roughened film A1 of the laminated film MIF5b (Example 18). A commercially available optical pressure-sensitive adhesive sheet was laminated on the polarizer surface of this polarizing plate. The transmission axis of the polarizer and the slow axis of the substrate film were parallel to each other.

  Physical properties and evaluations of these polarizing plates obtained from the respective laminated films are summarized in Table 6. Evaluation criteria for rainbow marks and contrast in the liquid crystal display device are as described later.

(Evaluation of liquid crystal display)
The polarizing plate on the viewing side and the light source side mounted on a liquid crystal display device (regza Z20X manufactured by Toshiba Corporation) having a KSF light source was peeled off, and instead, the obtained polarizing plate was bonded. Bonding is performed by laminating a commercially available optical adhesive sheet on the TAC surface in the case of a polarizing plate using a TAC film laminated polarizer, and in the case of a polarizing plate having a protective film on only one side, it is laminated on the polarizer surface The adhesive sheet side was pasted together. The transmission axis of the polarizer was made to be the same as the direction of the original liquid crystal display. In addition, the part of the liquid crystal cell which a polarizing plate can not cover completely was covered with black drawing paper.
Evaluation observed the confirmation of the rainbow mark and the contrast of the image.

(Observation of Rainbow Spots on Liquid Crystal Display)
The display of the liquid crystal display device was made white and the presence of rainbow marks was confirmed by viewing from the front and the oblique direction.
○: Rainbow spots were not observed.
Δ: Slightly iridescent spots were observed.
X: Rainbow spots were observed.

(Observation of contrast)
The display of the liquid crystal display was an image of a landscape, and the fluorescent light from the tabletop was irradiated from above to observe the contrast from the front.
◎: vivid contrast remained.
○: A slight decrease in contrast was observed due to scattered light.
Δ: A decrease in contrast was observed, but observation of the image was possible.
X: The image became difficult to see due to scattered light.

(Manufacture of circularly polarizing plate)
A λ / 4 wavelength plate was bonded to the adhesive layer surface of the single-sided protective film polarizing plate on which the adhesive of Examples 33 to 35 was laminated, to prepare a circularly polarizing plate. The circularly polarizing plate of the smart phone using commercially available organic EL was peeled off, and the circularly polarizing plate prepared instead was bonded to the organic EL cell, and the image was observed. These circularly polarizing plates were usable without any problem.

  In the case of using the laminated film of the present invention in the environment of a light source having a sharp peak, etc., it is possible to suppress rainbow marks, ensure high transparency, vivid image displayability, and suppress reflection by external light. it can.

Claims (3)

A laminated film having a base film and an optically isotropic layer having all the following features, wherein at least one surface of the laminated film is an antireflective surface having a moth-eye structure.
(A) At least one surface of the base film is an uneven surface, and the arithmetic average roughness (Ra) of the uneven surface is 0.2 to 10 μm.
(B) The refractive index anisotropy (Bfnx-Bfny) of a base film is 0.04-0.2.
(C) The optically isotropic layer is provided on the uneven surface of the base film, and the refractive index of the optically isotropic layer is Bfny-0.15 to Bfnx + 0.15.
(However, let the refractive index in the slow axis direction of the base film be Bfnx and the refractive index in the fast axis direction be Bfny) A polarizing plate using the laminated film according to claim 1 as a polarizer protective film. An image display apparatus comprising the polarizing plate according to claim 2.