JP2019124916A - Laminated film and polarizing plate using the same - Google Patents

Abstract

To provide a laminate which suppresses rainbow spots when used in an environment with a light source having a steep emission peak, and secures high transparency and capability to present clear images.SOLUTION: A laminate is provided, comprising a birefringent, transparent resin molded body laminated on a laminated film having features (a)-(c) below and comprising a base material film and an optically isotropic layer. (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) The 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.

  Liquid crystal display devices and organic EL display devices are often used for instruments of vehicles such as automobiles, motorcycles, ships, airplanes, etc. Furthermore, a monitor by a camera has been proposed as a substitute for backlights and door mirrors. Such instruments and monitors are provided with a transparent resin molded body cover. In addition, a digital signage or the like is often provided with a transparent resin cover sheet for protection or installed in a window frame in which the transparent resin sheet is inserted. These transparent resin molding covers and transparent resin sheets are often birefringent resins such as polycarbonate and styrene resin, and when viewed in polarized sunglasses, rainbow spots are caused by the orientation of the resin, making it difficult to see the display contents Was a problem. It has been proposed to combine films with high retardation to this problem, but even in this case, it has not been possible to sufficiently cope with a light source having a sharp peak or thinning.

  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 with low contrast.

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, the object of the present invention is to use a transparent laminate capable of suppressing rainbow marks and ensuring high transparency and vivid image displayability when used under an environment of a light source having a sharp emission peak, etc. Providing a display device.

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.
The laminated body by which the birefringent transparent resin molding was laminated | stacked on the laminated film which has a base film and an optical isotropic layer which have the characteristics of following (a)-(c).
(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.
A display device comprising the laminate according to item 1.
Item 3.
3. The display device according to item 2, wherein the laminate is a front cover plate of the display device.

  By using the transparent laminate of the present invention, when used under an environment of a light source having a sharp emission peak, rainbow blotches can be suppressed and high transparency can be secured.

In the laminate, a transparent resin molding is laminated on at least one surface of a laminate film having a substrate film of refractive index anisotropy having an uneven surface (rough surface) and an optically isotropic layer. Hereinafter, simply referred to as a laminated film means a laminated film of a substrate film of refractive index anisotropy having an uneven surface (roughened surface) and an optically isotropic layer. In one embodiment, the laminated body is provided as a cover for protecting the image display device on the viewing side of the display screen of the image display device that emits polarized light, and the laminated film is an image display device and a transparent resin molded body Provided between The image display device having such a configuration is also referred to as a “image display device with a molded body cover”. The observer of the image is configured to view the image through the transparent resin adult and the laminated film.
(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. 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 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.
In the specification, “average primary particle size” or “average particle size of primary particles” refers to 50% particle size of volume accumulation. More specifically, 200 primary particles are observed with an appropriate magnification by microscopic observation, each diameter is measured to calculate its volume, and 50% particle diameter of its volume accumulation is taken as the average primary particle diameter. Do.

  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.

  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.

  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 unevenness is relatively small and the rainbow spots are not sufficiently eliminated Preferably, the uneven surface and the optically isotropic layer are provided on both sides.

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 4, 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 a pressure-sensitive adhesive or a pressure-sensitive adhesive layer is used, a target is coated with a coating agent for pressure-sensitive adhesive and crosslinked or dried, or a substrate-less pressure-sensitive adhesive sheet is transferred. I mean one.

<Transparent resin molding>
A transparent resin molded product can be manufactured by appropriately selecting a known method from a thermoplastic resin having transparency. Examples of the raw material resin of the transparent resin molding include polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polystyrene (PS), acrylic resin, vinyl chloride resin, polymethylpentene (PMP) and the like. .

  The transparent resin molded product may have any shape as long as it has an image viewing part (display part) of the image display device installed in the opposite direction of the visible side and the transparent resin molded product, for example, a film or sheet , A curved surface, a housing or part of a housing.

  In the transparent resin molding, it is preferable that a portion having a retardation of 150 nm to 3500 nm, preferably 300 nm to 3000 nm, more preferably 500 to 2800 nm is typically present in the display portion.

  The thickness of the display portion of the transparent resin molding is arbitrary. For example, the thickness of the display portion is 0.1 to 5 mm, preferably 0.3 to 3 mm, and more preferably 0.5 to 2 mm.

  The manufacturing method of a transparent resin molding is not specifically limited, The molding method generally employ | adopted about the thermoplastic resin composition can be employ | adopted arbitrarily. For example, when the transparent molded product is an unstretched sheet, melt extrusion, calendar molding, injection molding, sheet press molding, vacuum molding, pressure forming, etc. may be mentioned. In addition, these unstretched sheets may be uniaxially or biaxially stretched. The transparent molded body may be a multilayer, and may be a stretched or unstretched film which is formed by in-mold molding, insert molding or the like. Moreover, when it has a complicated shape, it may be injection-molded.

  By providing the above-described laminated film between the display portion of the transparent resin molded product and the image display device, or on the viewing side of the display portion of the transparent resin molded product, iridescent spots and coloring that occur when viewed under polarized sunglasses Can be effectively reduced and eliminated. Among them, it is preferable to provide a laminated film between the display portion of the transparent resin molded product and the image display device in view of effectively reducing and eliminating rainbow stains and coloring. In the case where the laminated film is put on the viewing side of the display portion of the transparent resin molding, rainbow marks and coloring may occur depending on the angle when the head is inclined (angle of polarized sunglasses).

  When a laminated film is provided, the angle between the transmission axis direction of the polarizer of the most visible side polarizing plate of the display device and the slow axis or fast axis of the base film of the laminated film is preferably 20 to 45 degrees . The angle is more preferably 25 to 45 degrees, still more preferably 30 to 45 degrees, and particularly preferably 35 to 45 degrees. If the above range is exceeded, the change in brightness may be large when viewed with the head tilted. In particular, in the case where linearly polarized light is incident on the laminated film, the above-mentioned angle is preferable.

  In addition, when the transmission axis of the visual recognition side polarizer of an image display apparatus is about 45 degrees with respect to the short side of an image display apparatus, when installing a laminated film in the visual recognition side of a transparent resin molding, the basis of laminated film The angle between the slow axis or fast axis of the material film and the transmission axis of the polarizer is preferably 20 degrees or less, more preferably 15 degrees or less, and still more preferably 10 degrees or less.

  As a method of providing a lamination film between the display part of a transparent resin molding, and an image display device, if a lamination film exists between both, there will be no restriction in particular. For example, they may be attached to the viewing side of the image display device, or may be attached to the side opposite to the viewing side of the transparent resin molding. It may be a method of simply placing or hanging the laminated film at a desired position. When the laminated film is disposed, the transparent resin molded body side of the laminated film may be an optically isotropic surface or a substrate film surface. In the case of bonding, an adhesive or a pressure-sensitive adhesive is usually used. As described above, the adhesive or the adhesive may be an optically isotropic layer.

  When the transparent resin molded product is in the form of a sheet, it is also preferable to prepare a depolarizing laminate in which the sheet and the laminated film are bonded in advance. It is possible to cut the depolarizing laminate into a required size and provide it on the viewing side of the image display device, or fit it into the housing housing the image display device, the necessary part of the cover, and the window.

  The laminated film of the present invention may be provided with various functional layers on the surface according to each application. The various functional layers include a hard coat layer, an antiglare layer, an antireflective layer, a low reflection layer, a conductive layer, an antistatic layer, a colored layer, an ultraviolet absorbing layer, an antifouling layer, an adhesive layer and the like.

(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.

(Image display device)
The image display apparatus may emit linearly polarized light or elliptically polarized light. However, it is preferable to emit linearly polarized light because it can more effectively reduce iridescence and coloring. . In the case of an image display device that emits elliptically polarized light, rainbow marks and coloring may occur depending on the angle when the head is tilted (angle of polarized sunglasses). In a display device that emits linearly polarized light, the viewing side of the polarizer is usually a film with almost no retardation (100 nm or less), or even if the film has retardation, its fast axis or slow axis is of the polarizer. It is substantially parallel (less than 5 degrees) to the transmission axis. On the other hand, for those that emit elliptically polarized light, a film (greater than 100 nm) with retardation on the viewing side of the polarizer is provided, and its fast axis or slow axis is at least 5 degrees to the transmission axis of the polarizer There is.

  Examples of such an image display device include a liquid crystal display device and an organic EL display device provided with a circularly polarizing plate for reflection prevention on the surface. When the display device is elliptically polarized, a polyester film is often used as a substrate film of a touch panel or a scattering prevention film on the viewing side of a polarizer.

  In the case of a liquid crystal display device or an organic EL display device of a VA system or an IPS system, the transmission axis of the viewing side polarizer is generally parallel or perpendicular to the vertical direction (short side direction) of the screen. In such a case, the slow axis of the laminated film is preferably disposed at about 45 degrees (45 degrees ± 10 degrees or less) with the transmission axis of the polarizer. Moreover, it is preferable to arrange | position laminated | multilayer film in the light source side rather than a molded object. With such an arrangement, even when the user is looking at the screen by tilting the neck while wearing polarized sunglasses, rainbow unevenness hardly occurs. In addition, even if the polarized light emitted from the display device is linearly polarized light, elliptically polarized light (birefringent film such as PET as a touch panel substrate or scattering prevention film between the display device-molded product laminate film and λ / 4 retardation) The same applies to the case where a layer is provided.

  On the other hand, in the case of a liquid crystal display device of the TN type, generally, the transmission axis of the viewing side polarizer is approximately 45 degrees in the vertical direction (short side direction) of the screen. When the polarized light emitted from the display device is linearly polarized light, the laminated film is disposed closer to the light source than the molded body, and the slow axis of the laminated film is approximately 45 degrees (45 degrees ± 10 degrees or less) with the transmission axis of the polarizer. It is preferred to be arranged. If the laminated film is disposed on the visible side of the molded product, the slow axis of the laminated film is substantially parallel (0 degrees ± 10 degrees or less) or substantially perpendicular (90 degrees ± 10 degrees or less) to the transmission axis of the polarizer. Is preferred. The arrangement of the former is preferable in that the rainbow unevenness hardly occurs even when the user views the screen by tilting his / her head in a state of wearing polarized sunglasses. When the polarized light emitted from the display device is linear polarized light, the slow axis of the laminated film may be at any angle with the transmission axis of the polarizer as long as the laminated film is disposed on the light source side of the molded body . However, the rainbow unevenness can not be completely eliminated, and some rainbow unevenness may remain. If the laminated film is disposed on the visible side of the molded product, the slow axis of the laminated film is substantially parallel (0 degrees ± 10 degrees or less) or substantially perpendicular (90 degrees ± 10 degrees or less) to the transmission axis of the polarizer. Is preferred.

  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 display device including the laminate film of the present invention is reduced to a level at which iridescence can not be recognized even when it has a light source having a sharp emission peak, and the half value width of the emission peak of each color is narrow 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.

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 (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.

(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.

(Production of laminated films F1 to F17)
(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 optical isotropic layers with an applicator with an applicator, it was made to harden | cure from a coated surface with a high pressure mercury lamp, and laminated film F1 was obtained.

  Laminated films F2 to F16 were obtained in the same manner as in Example 1 except that the type of the surface roughened film and / or the coating agent was changed. In addition, the laminated film F14 provided the optically isotropic layer on both surfaces.

  A solution of Byron (registered trademark) 200 (RV 200) (made 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 and physical properties of the laminated films F1 to F17 are shown in Table 4.

Examples 1 to 26 and Comparative Examples 1 to 6
A commercially available adhesive sheet for optics was attached to one side of each of the laminated films F1 to F17, and an injection-molded product (10 cm × 10 cm × 1 mm) made of polycarbonate was further attached to obtain a laminate. The injection molded body has a gate portion at the center, and the orientation by resin flow remains from the center to the periphery.

Example 27
After coating the adhesive agent coating agent i (Arakawa Chemical Beamset OCA-6; after curing, refractive index 1.49) as an optically isotropic layer on the uneven surface of the surface roughened film A1 with an applicator, the coated surface Then, the resultant was cured with a high-pressure mercury lamp, and the above-mentioned molded body was bonded thereon, to obtain a laminate.

Example 28
A laminate was obtained in the same manner as in Example 27, except that the pressure-sensitive adhesive coating agent i was replaced by the following pressure-sensitive adhesive coating agent k, and drying was performed at 100 ° C.

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. The refractive index of the adhesive coating agent k after curing is 1.56.

Examples 29, 30, 31
After coating the coating agent b (Example 29), e (Example 30), or f (Example 31) for the optically isotropic layer on the irregular surface of the surface roughened film A1 with an applicator, from the coated surface It was made to harden | cure with a high pressure mercury lamp, the said molded object was bonded on it, and the laminated body was obtained.

(Evaluation of laminate)
(Observation of rainbow blotches)
Place the laminate so that the molded body is on the viewing side between the two polarizing plates arranged in cross nicol, and the slow axis of the base film is 45 degrees to the transmission axis of the polarizing plate on the light source side The state of transmitted light was observed from the front about 60 cm away from the polarizing plate on the viewing side, 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)
With the molded body of the laminate at the top, the halogen lamp was irradiated from below, and the degree of whitening of the laminate was evaluated from the direction of 45 degrees obliquely upward according to the following criteria.
◎: 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.

(Evaluation of liquid crystal display)
On the viewing side of a liquid crystal display (Legza Z20X manufactured by Toshiba Corporation) having a KSF light source, with the molded product of the obtained laminate facing up, and the slow axis direction of the base film of the laminate from the liquid crystal display The direction of the linearly polarized light emitted was set to be 45 degrees, and rainbow blotches and image contrast were observed.

(Observation of Rainbow Spots on Liquid Crystal Display)
The display on the liquid crystal display device was all white, and was put on polarized sunglasses, and the presence of rainbow marks was confirmed from the front and the oblique direction.
○: Rainbow spots were not observed Δ: Slight rainbow spots were observed ×: 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: Scattered light made the image difficult to see

  Table 5 shows the structure, physical properties and evaluation results of the laminate.

１＊：積層フィルム番号
２＊：粗面化フィルム番号
３＊：凹凸面
４＊：光学等方性層コート剤
５＊：光学等方層屈折率
６＊：成形体を積層した表面
７＊：接着層
８＊：虹斑評価
９＊：白化評価
１０＊：画像コントラスト
１１＊：虹斑

1 *: laminated film No. 2 *: roughened film No. 3 *: uneven surface 4 *: optical isotropic layer coating agent 5 *: optical isotropic layer refractive index 6 *: surface laminated with a molded body 7 *: Adhesive layer 8 *: rainbow mark evaluation 9 *: whitening evaluation 10 *: image contrast 11 *: rainbow mark

  The laminate of the present invention can suppress rainbow marks, secure high transparency, and / or vivid image display with high contrast when used under an environment of a light source having a sharp peak.

Claims (2)

The laminated body by which the birefringent transparent resin molded object was laminated | stacked on the laminated film which has a base film and an optical isotropic layer which has following characteristic (a)-(c).
(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) An image display apparatus comprising the molded body according to claim 1.