JP2017124621A - Multi-layered laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a UV cut multi-layered laminated film made of polyester, achieving low bleeding out properties with a thin film thickness, with iridescent fluctuation being prevented.SOLUTION: The multi-layered laminated film includes 51 or more layers of alternately laminated polyester resin A and polyester resin B, having a total light transmittance of 85% or more, a light transmittance at a wavelength of 380 nm of 40% or less, and a phase difference of 3000 nm or more.SELECTED DRAWING: None

Description

  The present invention relates to a multilayer laminated film.

  Polyester films having a UV cut function have been used for window glass of buildings and vehicles. Here, since such a polyester film is produced by biaxial stretching, it has a medium phase difference, and thus there is a problem that strong rainbow unevenness is seen when viewed through a polarizer such as polarized sunglasses. Even when not wearing polarized sunglasses, sunlight may be polarized due to scattering in the air or reflection from an object, and light from a light source such as a fluorescent lamp may be polarized due to reflection from the object. In such a case, the rainbow unevenness may be seen even with the naked eye, and the stronger rainbow unevenness will be seen through the polarized sunglasses.

  In recent years, there has been a demand for a polyester film having a UV cut function for a polarizing plate constituting a liquid crystal display device.

  A polarizing plate constituting a liquid crystal display device has a structure in which a polarizer and a polarizer protective film are laminated on both sides thereof, and has good adhesion and optical characteristics with the polarizer. A film made of a cellulose ester typified by acetyl cellulose (TAC) has been used. However, since the cellulose ester film has high moisture permeability, warping occurs in the polarizing plate in a high temperature and high humidity environment, causing problems such as display unevenness of the liquid crystal display device, and handling properties due to a decrease in mechanical strength when thinned. There is a problem that the UV cut property is lowered.

Instead of cellulose ester films, acrylic films and cyclic olefin films have begun to be used. However, the acrylic film still has high moisture permeability, and it has been difficult to completely eliminate warping of the polarizing plate. In addition, both acrylic films and cyclic olefin films have problems such as reduction in handling properties and UV cutability due to a decrease in mechanical strength when thinned.
In recent years, miniaturization of liquid crystal display devices has been desired, but for the purpose of thinning the polarizing plate for miniaturization of the device, if the film is thinned, the moisture permeability, handling properties, and UV-cutting properties deteriorate and the device is deteriorated. Miniaturization was difficult.
On the other hand, the stretched polyester film has low moisture permeability and has a characteristic of having sufficient mechanical strength even when it is thinned, and has an advantage for these problems. However, since a medium phase difference is developed by stretching, there is a problem that rainbow unevenness is visually recognized when the liquid crystal display device is viewed from a specific direction when the liquid crystal display device is turned on. Further, by balancing the longitudinal and lateral stretching, the front phase difference can be reduced, but it is difficult to reduce the thickness direction retardation.
As a method for solving such a problem, a method for suppressing rainbow unevenness by stretching polyester in a uniaxial direction to increase the phase difference has been proposed (Patent Document 1).
The UV-cutting means for cellulose-based, acrylic-based, cyclic olefin-based, and polyester-based films described above is based on the addition of an ultraviolet absorber, and when the film is made thin, the concentration of the ultraviolet absorber increases, so ultraviolet absorption There is a problem of bleeding out of the agent.

International Publication No. 2011-162198 Pamphlet

  An object of the present invention is to provide a UV-cut multilayer laminated film that suppresses rainbow unevenness and achieves thinning and low bleed-out properties while being a polyester film.

In order to solve the above problems, the present invention has the following configuration.
A multilayer laminated film of 51 or more layers in which a polyester resin A and a polyester resin B are alternately laminated, wherein the total light transmittance is 85% or more, the transmittance at a wavelength of 380 nm is 40% or less, and the phase difference is 3000 nm or more. A multilayer laminated film characterized by being:

  According to the present invention, it is possible to obtain a UV-cut multilayer laminated film that suppresses rainbow unevenness and achieves thinning and low bleed out properties.

The example of the in-plane refractive index distribution of A layer and B layer of the biaxial stretching multilayer laminated film of a conventional method. The example of the in-plane refractive index distribution of A layer and B layer of the biaxially-stretched multilayer laminated film stretched | stretched in the longitudinal direction of the conventional method strongly or the longitudinal direction. The preferable example of the in-plane refractive index distribution of A layer and B layer of the multilayer laminated film of this invention. The preferable example of the in-plane refractive index distribution of A layer and B layer of the multilayer laminated film of this invention. The more preferable example of the in-plane refractive index distribution of A layer and B layer of the multilayer laminated film of this invention. The figure explaining the relationship between the incident angle and phase difference of the multilayer laminated film of this invention. Diagram explaining azimuth The figure explaining the installation relationship of the polarizing plate or polarizer installed in the visual recognition side of the multilayer laminated film of this invention, and a display apparatus An example of a spectral spectrum of the multilayer laminated film of the present invention An example of a spectral spectrum of the multilayer laminated film of the present invention An example of the spectrum of a polarizing plate Example of liquid crystal display device Example of organic EL display device

  The present inventors are 51 or more multilayer laminated films in which polyester resin A and polyester resin B are alternately laminated, and the total light transmittance is 85% or more and the transmittance at a wavelength of 380 nm is 40% or less. It was found that by using a multilayer laminated film characterized in that the phase difference is 3000 nm or more, rainbow unevenness can be suppressed, thinning and low bleed-out properties can be achieved. This will be described in detail below.

  The polyester that can be used in the multilayer laminated film according to the present invention is preferably a polyester obtained using an aromatic dicarboxylic acid or aliphatic dicarboxylic acid and a diol or a derivative thereof. Here, as the aromatic dicarboxylic acid, for example, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyl Examples thereof include dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, and the like. Examples of the aliphatic dicarboxylic acid include adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexanedicarboxylic acid and ester derivatives thereof. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred. These acid components may be used alone or in combination of two or more thereof, and further may be partially copolymerized with oxyacids such as hydroxybenzoic acid.

  Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis (4- Hydroxyethoxyphenyl) propane, isosorbate, spiroglycol and the like. Of these, ethylene glycol is preferably used. These diol components may be used alone or in combination of two or more.

  Among the above polyesters, polyethylene terephthalate and copolymers thereof, polyethylene naphthalate and copolymers thereof, polybutylene terephthalate and copolymers thereof, polybutylene naphthalate and copolymers thereof, and polyhexamethylene terephthalate and copolymers thereof. Preference is given to using polymers and polyesters selected from polyhexamethylene naphthalate and copolymers thereof.

  In the multilayer laminated film of the present invention, at least two kinds of polyester resins are used, and the two kinds of polyester resins have different properties. The property here means that crystallinity / amorphous property, optical property, thermal property, or physical property is different. By laminating polyester resins having different properties, it is possible to give the film a function that cannot be achieved by a single layer film of each polyester resin.

  Moreover, as a preferable combination of the polyester resins having different properties used for the multilayer laminated film of the present invention, the absolute value of the difference in glass transition temperature of each polyester resin is preferably 20 ° C. or less. This is because if the absolute value of the difference in glass transition temperature is greater than 20 ° C., poor stretching is likely to occur when a multilayer laminated film is produced.

  A preferred combination of polyester resins having different properties used for the multilayer laminated film of the present invention is that the absolute value of the difference in SP value (also referred to as solubility parameter) of each polyester resin is 1.0 or less. Is preferable. When the absolute value of the difference in SP value is 1.0 or less, delamination hardly occurs. More preferably, the polymers having different properties are preferably composed of a combination provided with the same basic skeleton. The basic skeleton here is a repeating unit constituting the resin. For example, when polyethylene terephthalate is used as one polyester resin, it is the same as polyethylene terephthalate from the viewpoint of easily realizing a highly accurate laminated structure. It is preferable to contain ethylene terephthalate which is a basic skeleton. When the polyester resins having different optical properties are resins containing the same basic skeleton, the lamination accuracy is high, and delamination at the lamination interface is difficult to occur.

  In order to have the same basic skeleton and different properties, a copolymer is desirable. That is, for example, when one resin is polyethylene terephthalate, the other resin is an embodiment using a resin composed of an ethylene terephthalate unit and another repeating unit having an ester bond. The proportion of other repeating units (sometimes referred to as copolymerization amount) is preferably 5% or more because of the need to obtain different properties. On the other hand, since the difference in adhesion between layers and thermal fluidity is small, each layer The thickness is preferably 90% or less because of excellent thickness accuracy and thickness uniformity. More preferably, it is 10% or more and 80% or less. It is also desirable that the A layer and the B layer are used by blending or alloying a plurality of types of polyester resins. By blending or alloying a plurality of types of polyester resins, performance that cannot be obtained with one type of polyester resin can be obtained.

In the multilayer laminated film of the present invention, 51 layers or more of layers made of polyester resin A (layer A) and layers made of polyester resin B having different properties from the resin constituting layer A (layer B) are alternately laminated. It is necessary that the total light transmittance is 85% or more and the transmittance at a wavelength of 380 nm is 40% or less.
The total light transmittance is preferably 90% or more, more preferably 92% or more, and the wavelength 380 nm transmittance is preferably 20% or less. The average transmittance at a wavelength of 240 nm to 380 nm is preferably 5% or less, more preferably 1% or less.
The following formula (1) is a formula representing the reflection wavelength determined from the refractive index and the layer thickness of the adjacent A layer and B layer. By designing the resin and layer thickness of the A layer and the B layer so as to satisfy the following formula (1), optical characteristics with a total light transmittance of 85% or more and a transmittance of 40% or less at a wavelength of 380 nm can be obtained. .

Here, λ is the reflection wavelength, n _A is the in-plane refractive index of the A layer, d _A is the thickness of the A layer, n _B is the in-plane refractive index of the B layer, and d _B is the thickness of the B layer.
The thickness of each suitable layer which satisfy | fills Formula (1) is 60 nm or less. The multilayer laminated film of the present invention is characterized in that light having a wavelength of 380 nm and a wavelength in the ultraviolet region is cut by reflection when the thickness of each layer is 60 nm or less. As a result, the amount of the UV absorber added is smaller than that of the conventional UV cut film, and the film thickness is reduced and the bleed-out property is excellent.
The method for adjusting the reflectance in the desired wavelength range is the in-plane refractive index difference between layer A and layer B, the number of layers, the layer thickness distribution, and the film forming conditions (for example, the stretching ratio, stretching speed, stretching temperature, heat treatment temperature, heat treatment time). ) Adjustment and the like. Since the reflectivity increases and the number of stacked layers can be reduced, the in-plane refractive index difference between the A layer and the B layer is preferably 0.02 or more, more preferably 0.04 or more, and further preferably 0.08 or more.

  The layer thickness distribution increases or decreases from one side of the film surface to the opposite surface, the layer thickness distribution decreases after the layer thickness increases from one of the film surfaces toward the film center, and the film A layer thickness distribution or the like that increases after the layer thickness decreases from one of the surfaces toward the center of the film is preferable. Layer thickness distribution can be changed continuously, such as linear, geometric ratio, difference series, or 10 to 50 layers have almost the same layer thickness, and the layer thickness is stepped. Those that change are preferred. The higher the number of stacked layers, the higher the ultraviolet reflectance can be realized and the reflection bandwidth can be expanded, but the upper limit is about 4001 layers from the viewpoint of stacking accuracy and increase in the size of the stacking apparatus.

  The multilayer laminated film of the present invention preferably has a color tone C value of reflected light of 3 or less, more preferably 1 or less. As a method of setting the color tone C value of reflected light to 3 or less, the layer thickness design is such that the interference wavelength is 380 nm or less based on Equation 1, the surface layer is thickened, or the surface layer and the layer near the surface layer are thinned. The method of doing is mentioned.

  As a method for thickening the surface layer, a layer having a layer thickness of 3 μm or more can be preferably provided as a protective layer on the surface layer of the multilayer laminated film. The thickness of the protective layer is preferably 5 μm or more. By increasing the thickness of the protective layer, it is possible to obtain a flat spectral spectrum in which ripples in the transmittance / reflectance spectrum in visible light are suppressed, and the color tone C value of the reflected light can be lowered. When the thickness of the protective layer is 3 μm or more, it can be handled as a layer that does not affect the formula (1). Other effects of the protective layer include suppression of flow marks, lamination with other films and molded bodies, suppression of deformation of the thin film layer in the multilayer laminated film after the lamination, and pressure resistance.

As a method of thinning the surface layer and the layer in the vicinity of the surface layer, the layer thickness is preferably 60 nm or less, more preferably 50 nm or less over at least 30 layers from the film surface toward the opposite surface. When the layer near the surface layer is 60 nm or less, the reflected light spectrum of visible light becomes flat, and coloring of reflected light can be suppressed.
Moreover, the protective layer thickness of both surface layers may be asymmetric. For example, by increasing the thickness of the protective layer on the surface laminated with another film or molded body to 3 μm or more, the deformation of the thin film layer in the multilayer laminated film is suppressed, and the layer thickness in the vicinity of the opposite surface is 60 nm or less. It is also possible to make it. In this case, it is preferable to laminate a hard coat layer or a support such as glass that is difficult to deform on the opposite surface.
As a method for increasing the total light transmittance, it is preferable to provide a primer layer, a hard coat layer, and an antireflection layer on the surface of the multilayer film of the present invention. The total light transmittance can be increased by providing a layer having a lower refractive index than the resin on the surface of the multilayer film.
The multilayer laminated film of the present invention preferably has a haze value of 3% or less, more preferably 1.5% or less, and still more preferably 1.0% or less. Since the haze value is small, it is possible to clearly see the scenery and video through the multilayer laminated film.

The multilayer laminated film of the present invention needs to have a retardation of 3000 nm or more. The phase difference here refers to a phase difference obtained by a measurement method described later when the incident angle is 0 °. When the phase difference is 3000 nm or more, rainbow unevenness when the polarized light that has passed through the multilayer laminated film of the present invention is visually recognized can be suppressed.
The retardation of the multilayer laminated film is represented by the following formula (2).

Where R is the phase difference, Δn _A is the birefringence index in the film plane of the A layer, Σd _A is the sum of the thicknesses of the A layer in the multilayer laminated film, Δn _B is the birefringence index in the film plane of the B layer, Σd _B is the sum total of B layer thickness in a multilayer laminated film.

Increasing the phase difference is achieved by increasing the birefringence of each layer and increasing the thickness of each layer.
As an example of the manufacturing method of the multilayer laminated film of the present invention, the polyester resin of the A layer and the B layer is melted and laminated, and an unstretched polyester film extruded into a sheet is longitudinally stretched at a temperature equal to or higher than the glass transition point. The method of extending | stretching and heat-processing to a horizontal direction after extending | stretching to a direction is mentioned.
The method for increasing the birefringence is achieved by uniaxial stretching in one of the longitudinal direction or the transverse direction, or biaxial stretching strongly stretched in either the longitudinal direction or the transverse direction. It is preferable to use a resin having a high birefringence, such as phthalate, for the A layer.

In order to increase the reflectance in the conventional biaxially stretched multilayer laminated film, a crystalline polyester is used for the A layer resin, and a crystalline polyester having a melting point lower than that of the A layer resin by −20 ° C. or more is used for the B layer resin. As shown in FIG. 1, the in-plane refractive indices of the A layer and the B layer are obtained by a method of applying a heat treatment temperature of the B layer resin or more and the A layer resin or less, or a method using an amorphous resin that is difficult to be stretched and oriented in the B layer resin. Difference 5 was increased.
However, in the conventional method, when uniaxial stretching performed to increase the phase difference or biaxial stretching performed strongly in one direction is performed, for example, as shown in FIG. Although the in-plane refractive index difference increases, the in-plane refractive index difference in the width direction between the A layer and the B layer decreases. For this reason, there is a problem that large unevenness occurs in the reflectance in the film plane.

  The in-plane refractive indexes of the A layer and the B layer of the multilayer laminated film of the present invention preferably have distributions as shown in FIGS. 3, 4, and 5 as preferable examples.

  In order to obtain the in-plane refractive index distribution shown in FIG. 3, a crystalline polyester is used for the A layer resin, and the B layer resin has a higher refractive index than the A layer resin in the in-plane refractive index in an unstretched state. Is preferably used.

  For the in-plane refractive index shown in FIG. 4, a crystalline polyester is used for the A-layer resin, and the B-layer resin has a lower refractive index than the A-layer resin in the in-plane refractive index in an unstretched state. Is preferably used.

  In order to obtain the in-plane refractive index distribution shown in FIG. 5, both the A layer resin and the B layer resin use a resin that exhibits a birefringence by stretching, and the B layer resin has a lower in-plane refractive index than the A layer resin. Is preferably selected. For example, by using a crystalline polyester for the A layer and a layer obtained by copolymerizing or blending an amorphous polyester with the crystalline polyester used for the A layer, the B layer has birefringence. The internal refractive index can be made lower than that of the A layer.

  In the method of FIGS. 1 to 4, the B layer resin is almost non-oriented and the birefringence takes a value close to zero. Therefore, only the A layer contributes to the retardation of the multilayer laminated film. On the other hand, since the B layer also has birefringence in the method of FIG. 5, both the A layer and the B layer contribute to the retardation of the multilayer laminated film, and the retardation can be further increased.

  The relationship between the incident angle and the phase difference of the multilayer laminated film of the present invention will be described with reference to FIG. In the figure, the slow axis 10 is the direction in which the average refractive index of the A layer and the B layer is highest in the film plane, and the fast axis 11 is the average refraction of the A layer and the B layer in the film plane. It is the direction with the lowest rate. The average refractive index referred to here is obtained by averaging the refractive indexes in the film in-plane direction of the A layer and the B layer by the layer thicknesses of the A layer and the B layer. When the incident angle of light is 0 ° (the following equation (3)), when the incident angle of light is inclined in the direction from 0 ° to 12 (the following equation (4)), the incident angle of the light is 0 ° to 13 Respective phase differences when tilted in the direction (the following formula (5)) are shown in formulas (3) to (5).

Here, R is the phase difference, Σd _A and Σd _B are the total thicknesses of the A layer and B layer in the multilayer laminated film, respectively, and n _Aα and n _Bα are the refractions in the slow axis direction of the A layer and B layer, respectively. , N _Aβ and n _Bβ are the refractive indexes in the _fast axis direction of the A layer and B layer, respectively, θ _A and θ _B are the refraction angles of the light traveling through the A layer and B layer, and n _Aβγ and n _Bβγ are respectively A The refractive index obtained by averaging the refractive index in the _fast axis direction and the refractive index in the thickness direction of the layer and the B layer by the refraction angle, n _Aαγ and n _Bαγ are the refractive index and the thickness direction in the slow axis direction of the A layer and the B layer, respectively. Is a refractive index obtained by averaging the refractive indexes of the above by the refraction angle. Further, the refractive indexes obtained by averaging the thickness direction refractive indexes in the slow axis direction and the fast axis direction of each of the A layer and the B layer are n _Aγ and n _Bγ .
Relationship of the refractive index of the A layer and the B layer in one embodiment of the multilayer laminate film of the present _{invention, n Aα> n Aβ >> n} Aγ _{and, n Bα = n Bβ = n} Bγ, become. In this case, when the incident angle is inclined in the direction of 12 with respect to the phase difference with an incident angle of 0 °, the phase difference increases as the incident angle increases from the equation (4). On the other hand, when the incident angle is inclined in the direction of 13, the phase difference decreases as the incident angle increases from the equation (5). Therefore, even if rainbow unevenness is not seen in the multilayer laminated film at an incident angle of 0 °, rainbow unevenness may be seen when the multilayer laminated film is viewed from 13 directions. Also, one of the alternative _{embodiment, n Aα> n Aβ >> n} Aγ _and, n Bα> n Bβ >> See multilayer laminate film from the same direction as the 13 even in the case of n _Biganma the rainbow stains There is a risk of seeing. This is because when the resin having positive birefringence is used as the polyester-based resin for the multilayer laminated film of the present invention, the refractive index in the thickness direction becomes smaller than the refractive index in the film in-plane direction by stretching. is there. Therefore, the multilayer laminated film of the present invention preferably has a phase difference of 3000 nm or more over a range of incident angles from 0 ° to 50 °, which is a general viewing angle. More preferably, the phase difference is 3000 nm or more over an angle range of incident angles of 0 ° to 60 °, and still more preferably, the phase difference is 3000 nm or more over an angle range of incident angles of 0 ° to 80 °. In this way, even if the incident angle is increased, the rainbow unevenness cannot be seen, so that a wide viewing angle can be obtained. One way to achieve this is to make the phase difference at an incident angle of 0 ° greater than 3000 nm. If the phase difference at an incident angle of 0 ° is larger than 3000 nm, the incident angle increases, and even when the phase difference decreases, the phase difference of 3000 nm or more can be maintained. Another method is to control the refractive index in the thickness direction. When the refractive index in the thickness direction is increased, the degree of decrease in retardation can be reduced, and when it is higher than in the film plane, even when the incident angle is tilted in the direction of 13, the phase difference is increased as the incident angle is increased. Can do. Suitable resins include bulky skeletons that suppress plane orientation and polyester resins having side chains.

  In the multilayer laminated film of the present invention, it is preferable that either one or both of polyester resin A and polyester resin B contains naphthalenedicarboxylic acid as a dicarboxylic acid component. Since naphthalenedicarboxylic acid has absorption in the UV region on the long wavelength side, the UV cut property of the multilayer laminated film can be improved. More preferably, the polyester resin A is a crystalline polyester obtained by copolymerizing polyethylene naphthalate or naphthalenedicarboxylic acid. Crystalline polyester having a naphthalenedicarboxylic acid component has high birefringence and is effective for increasing the phase difference.

  The polyester resin A contains polyethylene terephthalate as the main component, the polyester resin B contains terephthalic acid as the dicarboxylic acid component, and ethylene glycol as the diol component, and naphthalenedicarboxylic acid and cyclohexanedicarboxylic acid as the dicarboxylic acid component. The diol component is preferably a polyester mainly comprising at least one copolymer component among cyclohexanedimethanol, spiroglycol and isosorbide. In the above resin configuration, since the difference in refractive index between the polyester resin A and the polyester resin B becomes large, it is possible to have a high UV cut property due to UV reflection.

The multilayer laminated film of the present invention preferably comprises an ultraviolet absorber. Since the multilayer laminated film of the present invention has a UV cut function by UV reflection, there is an advantage that the concentration of the absorbent added is small compared to a film having the same thickness that does not have the UV reflection function. The addition of the ultraviolet absorbent to the multilayer laminated film is preferably adjusted by adjusting the concentration of the ultraviolet absorbent, the thickness of the multilayer laminated film, and the thickness of the layer to which the ultraviolet absorbent is added. In particular, it is preferable to add an ultraviolet absorber other than the surface layer of the multilayer laminated film, more preferably the B layer.
Examples of the ultraviolet absorber include an organic ultraviolet absorber and an inorganic ultraviolet absorber, and an organic ultraviolet absorber is preferable from the viewpoint of transparency. Examples of the ultraviolet absorber include benzotriazole, benzophenone, triazine, and benzoxazinone. The addition amount of the ultraviolet absorber is preferably in the range of 0.1 wt% to 10.0 wt%, more preferably in the range of 0.1 wt% to 4.0 wt%, and more preferably in the range of 0.1 wt% to 2.0 wt%. .
Moreover, it is also preferable to add a hindered amine light stabilizer (HALS) in the range of 0.1 wt% to 3.0 wt%, and more preferably in the range of 0.1 wt% to 1.0 wt%.

  The multilayer laminated film of the present invention preferably contains a triazine-based ultraviolet absorber, and more preferably has a molecular weight of 600 or more. The triazine-based ultraviolet absorber is excellent in heat resistance and bleed-out suppression effect. Therefore, there is little process contamination at the time of multilayer laminated film manufacture. Moreover, precipitation of the UV absorber in the reliability test such as heat resistance and heat resistance of the multilayer laminated film is suppressed, and the stability of the optical characteristics is excellent.

  It is also preferable to use a blend of a triazine-based ultraviolet absorber and another ultraviolet absorber. Even if it is only one type, even if it is an ultraviolet absorber with bad bleed-out property and precipitation property, bleed-out property and precipitation property can be improved by blending with a triazine type.

The film thickness of the multilayer laminated film of the present invention can be in the range of 15 μm to 200 μm, for example. Among these, the range of 15 μm to 60 μm is preferable. Moreover, if it is a polarizer protection use, the range of 15 micrometers-100 micrometers is preferable, More preferably, it is the range of 15 micrometers-40 micrometers.
The multilayer laminated film of the present invention has a primer layer, a hard coat layer, an abrasion resistant layer, an anti-scratch layer, an antireflection layer, a color correction layer, an ultraviolet absorption layer, a light stabilization layer (HALS) heat ray absorption on the film surface. It is preferable that functional layers such as a layer, a printing layer, a gas barrier layer, and an adhesive layer are formed. These layers may be one layer or multiple layers, and one layer may have a plurality of functions.

  In addition, the multilayer laminated film of the present invention is preferably formed into a laminate by further providing a layer containing an ultraviolet absorber. It is preferable to provide an ultraviolet absorbing layer on at least one film surface. The form of the ultraviolet absorbing layer is not particularly limited, but a form in which an ultraviolet absorber is contained in the hard coat layer or the adhesive layer is preferable. It is also preferable to provide a hard coat layer on one surface of the multilayer laminated film and an adhesive layer on the other surface. In this case, the ultraviolet absorber may be contained in one or both layers, and not only one type of ultraviolet absorber but also a plurality of types of ultraviolet absorbers may be used. It is also preferable to change the number and content. By providing the ultraviolet absorbing layer on the surface of the multilayer laminated film, it is possible to enhance the UV cut property of the entire film. Moreover, when laminating a multilayer laminated film on a window member or a display, the reflective color of UV to visible light by the multilayer laminated film can be suppressed by making the viewing side a layer provided with an ultraviolet absorber. The absorption wavelength of the ultraviolet absorber preferably absorbs a wavelength of 380 nm or less, absorbs a wavelength of 420 nm or less, and does not absorb a wavelength of 421 nm or more, particularly 430 nm or more.

The multilayer laminated film of the present invention is preferably used for a display device. Among these, it is preferably used for a display device having a polarizing plate and / or a polarizer satisfying the following formula (6), and satisfying the following formulas (7) and (8).
0 ° ≦ | Φ1-Φ2 | <45 ° (6)
Rmax ≧ 20% (7)
Rmax−Rmin> 5% (8)
(Where Φ1 is the azimuth angle taking Rmax in the plane of the multilayer laminated film, and Φ2 is the azimuth angle of the transmission axis of the polarizing plate or polarizer placed on the viewing side of the display device. The laminated film is irradiated with linearly polarized light at an incident angle of 0 °, and with the incident optical axis of the multilayer laminated film as the center, the arbitrary azimuth direction on the multilayer laminated film surface is 0 °, and linearly polarized light at intervals of 5 ° up to 180 °. Is the maximum value of the maximum reflectance in the wavelength range of 381 nm to 420 nm at each azimuth angle measured by half-rotating the azimuth angle, and Rmin is the maximum in the wavelength range of 381 nm to 420 nm at the azimuth angle orthogonal to Φ1. Reflectivity.)
The azimuth angle will be described with reference to the drawings. FIG. 7 is a top view of the surface of the multilayer laminated film or display device. Here, 17 and 18 in FIG. 7 are arbitrary directions having a right angle relationship. If the vibration direction of linearly polarized light incident on the multilayer laminated film at an incident angle of 0 ° or the direction of the transmission axis of the polarizing plate or polarizer installed on the viewing side of the display device is 20, the azimuth is the direction 20 And an angle 21 between the direction 18 and the direction 18.

  FIG. 8 shows a preferable installation relationship between the multilayer laminated film of the present invention and a polarizing plate or a polarizer installed on the viewing side of the display device. The multilayer laminated film 22 of the present invention is installed on the viewing side with respect to the polarizing plate or the polarizer 24 installed on the viewing side of the display device, and has an azimuth angle (Φ1) 23 ′ taking Rmax in the multilayer laminated film plane. The polarizing plate or the polarizer installed on the viewing side of the display device is installed so as to satisfy Expression (6) with respect to the azimuth angle (Φ2) 25 ′ of the transmission axis. Preferably, Φ1 and Φ2 are installed so as to be substantially parallel, and 0 ° ≦ | Φ1-Φ2 | <30 ° is preferable, and more preferably 0 ° ≦ | Φ1-Φ2 | <15 °. Yes, the most effective installation orientation is | Φ1-Φ2 | = 0 °.

  A polarizing plate installed on the viewing side of the display device so that the multilayer laminated film of the present invention satisfies the formulas (7) and (8) and the multilayer laminated film of the present invention satisfies the formula (6); By using it installed in a polarizer, long wavelength UV light in a wavelength range of 381 nm to 420 nm entering the display device from the outside (viewing side) of the display device can be sufficiently cut. On the other hand, since reflection of long-wavelength UV light can be suppressed as compared with the conventional multilayer laminated film, it is possible to suppress coloring and glare of the screen due to reflected light. While performing sufficient long wavelength UV light cut, it demonstrates using a figure about suppressing reflection of long wavelength UV light rather than the conventional multilayer laminated film. 9 and 10 show an example of the spectrum of the multilayer laminated film of the present invention, and FIG. 11 shows an example of the spectrum of the polarizing plate. In order to increase the retardation, the multilayer laminated film of the present application is uniaxially stretched in one direction of the longitudinal direction or the transverse direction, or biaxially stretched strongly in either the longitudinal direction or the transverse direction. The long wavelength UV light cutting property in the direction is excellent, while the long wavelength UV light cutting property in the Rmin direction is insufficient. On the other hand, the polarizing plate is excellent in the long wavelength UV light cutting property in the absorption axis direction, but lacks the long wavelength UV light cutting property in the transmission axis direction. As described above, the long wavelength UV cut property in one azimuth angle direction is excellent, while the other, generally, the long wavelength UV cut property in the orthogonal direction is insufficient. By laminating such a multilayer laminated film and a polarizing plate so as to satisfy 0 ° ≦ | Φ1−Φ2 | <45 °, the direction in which the long wavelength UV light cut property is excellent is the long wavelength UV light cut property. In order to compensate for the UV cut in the shortage direction, it is possible to have a sufficient cut property for long wavelength UV light in each azimuth direction. Light (external light) that enters the display device from the outside (viewing side) of the display device is generally elliptically polarized light. The reflectance with respect to external light of the multilayer laminated film of the present application is an average of the Rmax orientation and the Rmin orientation in FIG. 9, and the reflectance is suppressed more than Rmax. On the other hand, the reflectance with respect to the external light of the multilayer laminated film which biaxially stretched equally in both the vertical and horizontal directions is a reflectance close to that in FIG. 9 (Rmax orientation). Therefore, the multilayer laminated film of the present application has a lower reflectance with respect to external light than before, and as a result, it is possible to suppress the coloring and glare of the screen due to the reflected light. From the viewpoint of sufficient long-wavelength UV light cutability, Rmax is more preferably 40% or more, further preferably 60% or more, and particularly preferably 90% or more. Moreover, in the azimuth angle which takes Rmax, it is preferable that the average reflectance of wavelength 400nm -420nm is 20% or more, More preferably, it is 40% or more, More preferably, it is 60% or more. The difference between Rmax and Rmin is more preferably 10% or more, further preferably 20% or more, and particularly preferably 40% or more from the viewpoint of suppressing reflectance with respect to external light. Further, the value of Rmin is preferably 15% or less, more preferably 10% or less, and further preferably 5% or less. Rmin / Rmax, which is the ratio of Rmin to Rmax, is also preferably 0.9 or less, more preferably 0.7 or less, and still more preferably 0.4 or less.

  The most preferable mode is to install it so that | Φ1-Φ2 | = 0 °, and set Rmin = 0%. By setting it so that | Φ1-Φ2 | = 0 °, the long-wavelength UV light cutting performance can be most exhibited. By setting Rmin = 0%, the reflectance of external light is higher than that of the conventional method. Can be halved. By sufficiently cutting long-wavelength UV light in the wavelength range of 381 nm to 420 nm, it is possible to prevent deterioration in the display device, and it is particularly suitable for preventing deterioration of the light emitting element of the organic EL display device. In general, the azimuth angle taking Rmax and the azimuth angle taking Rmin are orthogonal, and the azimuth angle taking the transmission axis and the azimuth angle taking the absorption axis are orthogonal.

  While it is preferable to sufficiently cut long wavelength UV light in the wavelength range of 381 nm to 420 nm, the transmittance at a wavelength of 440 nm is preferably 50% or more, more preferably 60% or more from the viewpoint of sufficiently transmitting light emitted from the display device. More preferably, it is 70% or more, and particularly preferably 80% or more.

  The multilayer laminated film or laminate of the present invention is preferably used for a liquid crystal display device or an organic EL display device. Examples of a display device using the multilayer laminated film or laminate of the present invention are shown in FIGS. As the use of the multilayer laminated film or laminate of the present invention, it is a liquid crystal display device comprising at least a first polarizing plate, a liquid crystal layer, a second polarizing plate, and an LED light source in this order. Examples thereof include a liquid crystal display device in which a film or a laminate is laminated as a viewer-side polarizer protection of the first polarizing plate or laminated on the viewer side of the first polarizing plate. When laminating | stacking on the visual recognition side rather than a 1st polarizing plate, using the film of this invention as a screen protective film bonded together to a cover glass and the touchscreen base film which forms a transparent conductive layer is mentioned. Another application of the multilayer laminated film or laminate of the present invention includes an organic EL display device equipped with a polarizing plate, and the multilayer laminated film or laminate of the present invention is laminated as a polarizer for viewing side polarizer protection. Alternatively, it may be laminated on the viewing side with respect to the polarizing plate. When laminating | stacking on the visual recognition side rather than a polarizing plate, using the multilayer laminated film or laminated body of this invention as a screen protection film bonded to a cover glass and the touchscreen base film which forms a transparent conductive layer is mentioned.

  The example of the specific aspect which manufactures the multilayer laminated film of this invention is described below. The laminated structure of 51 layers or more in the multilayer laminated film of the present invention can be produced by the following method. A thermoplastic resin is supplied from two extruders A corresponding to the A layer and an extruder B corresponding to the B layer, and the polymer from each flow path is a known multi-manifold type feed block, Laminate 51 layers or more by using a square mixer or a comb type feed block, and then melt extrude the melt into a sheet using a T-type die, and then cool it on a casting drum. The method of solidifying and obtaining an unstretched multilayer laminated film is mentioned. As a method for increasing the stacking accuracy of the A layer and the B layer, methods described in Japanese Patent Application Laid-Open No. 2007-307893, Japanese Patent No. 4619910, and Japanese Patent No. 4816419 are preferable. If necessary, it is also preferable to dry the thermoplastic resin used for the A layer and the thermoplastic resin used for the B layer.

Subsequently, the unstretched multilayer laminated film is subjected to stretching and heat treatment. The stretching method is preferably biaxially stretched by a known uniaxial stretching method, sequential biaxial stretching method, or simultaneous biaxial stretching method.
In the uniaxial stretching method, stretching is preferably performed in one direction of the longitudinal method, the width direction, and the intermediate direction (oblique direction) between the longitudinal direction and the width direction.
In the biaxial stretching method, it is preferable to stretch strongly in any one of the longitudinal method, the width direction, and the intermediate direction (oblique direction) between the longitudinal direction and the width direction, and weakly stretch in the other direction. Moreover, you may perform extending | stretching to each direction combining several times.

  The stretching temperature is preferably within the range of the glass transition temperature of the unstretched multilayer laminated film to the glass transition temperature + 80 ° C. or less. In the case of performing stretching several times, it is preferable to gradually increase the stretching temperature.

  If the stretching ratio is uniaxial stretching, the range of 3 to 10 times is preferable, and the range of 4 to 6 times is more preferable.

  In the case of biaxial stretching, a range of 3 to 7 times is preferable in the direction of strong stretching, and a range of 1.1 to 3 times is preferable in the direction of weak stretching. Moreover, when extending | stretching to the same direction in multiple times, it is preferable to make magnification smaller than the 1st time for the extending | stretching after the 2nd time.

  The stretching in the longitudinal direction is preferably performed by utilizing a speed change between the longitudinal stretching machine rolls. The stretching in the width direction uses a known tenter method. That is, it conveys while holding both ends of a multilayer laminated film with a clip, and extends | stretches in the width direction by widening the clip space | interval of both ends of a multilayer laminated film. Stretching in the middle direction (diagonal direction) between the longitudinal direction and the width direction can be achieved by gradually changing the orientation of the longitudinal stretching roll, or by moving the clips at both ends of the multilayer laminated film within the tenter. And a stretching method.

  Moreover, it is also preferable to perform simultaneous biaxial stretching for stretching with a tenter. The case where simultaneous biaxial stretching is performed will be described. Unstretched multilayer laminated film cast on chill roll is guided to a simultaneous biaxial tenter and conveyed while holding both ends of the multilayer laminated film with clips, and stretched in the longitudinal and width directions simultaneously and / or stepwise To do. Stretching in the longitudinal direction is achieved by increasing the distance between the clips of the tenter and in the width direction by increasing the distance between the rails on which the clips run. The tenter clip subjected to stretching and heat treatment in the present invention is preferably driven by a linear motor system. In addition, there are a pantograph method, a screw method, etc. Among them, the linear motor method is excellent in that the stretching ratio can be freely changed because the degree of freedom of each clip is high.

It is preferable to perform heat treatment after stretching. The heat treatment temperature is preferably in the range from the stretching temperature to the melting point of the multilayer laminated film −10 ° C. or less, and after the heat treatment, the cooling step in the range from the glass transition temperature of the multilayer laminated film to the heat treatment temperature −30 ° C. or less. It is also preferable to go through. Moreover, it is also preferable to perform the heat treatment immediately after the drawing and after cooling to the drawing temperature or lower. By lowering the temperature of the multilayer laminated film after stretching to give rigidity, bowing that occurs in the multilayer laminated film in the heat treatment step can be suppressed, and a uniform phase difference can be obtained over a wide range in the width direction of the multilayer laminated film. An orientation angle can be obtained.
It is also preferable to perform stretching by 2% or more and 20% or less immediately after the heat treatment step. By performing such stretching, the retardation of the multilayer laminated film can be further increased, the generated bowing can be suppressed, and the uniform retardation and orientation can be achieved over a wide range in the width direction of the multilayer laminated film. You can get a corner.
In order to reduce the thermal shrinkage rate of the film, it is also preferable to shrink (relax) the film in the width direction and / or the longitudinal direction during the heat treatment step or the cooling step. The relaxation rate is preferably in the range of 1% to 10%, more preferably in the range of 1 to 5%. In order to suppress the bowing and reduce the thermal shrinkage rate, the film is stretched in the width direction and / or during the heat treatment step or after the heat treatment step or after the stretching of 2% or more and 20% or less immediately after the heat treatment step. Or it is preferable to shrink in the longitudinal direction.
Finally, the multilayer laminated film of the present invention is produced by winding the film with a winder.
As a use of the multilayer laminated film of the present invention, it is preferably used as a window or window member of a building or vehicle, or a polarizer protective film.

Hereinafter, the multilayer laminated film of the present invention will be described with reference to specific examples. Even when a polyester resin other than the polyester resin specifically exemplified below is used, the multilayer laminated film of the present invention can be obtained in the same manner by taking into consideration the description of the present specification including the following examples. .
[Methods for measuring physical properties and methods for evaluating effects]
The physical property value evaluation method and the effect evaluation method are as follows.

(1) Transmittance and reflectance A 12 ° specular reflection accessory device P / N134-0104 attached to a spectrophotometer (U-4100 Spectrophotometer) manufactured by Hitachi, Ltd. is attached, and a wavelength of 240 to 240 at an incident angle φ = 12 degrees is attached. The absolute reflectance and transmittance at 800 nm were measured. Measurement conditions: The slit was 2 nm (visible) / automatic control (infrared), the gain was set to 2, and the scanning speed was 600 nm / min. A sample was cut out at 4 cm × 4 cm from the center of the film width and measured. From these results, the transmittance and reflectance at a wavelength of 380 nm and the transmittance at a wavelength of 440 nm were determined.

  Rmax and Rmin were measured as follows. The attached Grande Taylor polarizer was installed, and the absolute reflectance at a wavelength of 240 to 800 nm was measured at each azimuth angle in which the polarization component was rotated in increments of 5 ° at an azimuth angle of 0 ° to 180 °. From these measurement results, the maximum reflectance in a wavelength range of 381 nm to 420 nm at each azimuth angle was obtained, and the largest reflectance among them was defined as Rmax, and the azimuth angle was defined as Φ1. The maximum reflectance in the wavelength range of 381 nm to 420 nm in the azimuth angle direction where the azimuth angle formed with Φ1 is 90 ° was defined as Rmin. Moreover, the average reflectance of wavelength 400nm -420nm in the azimuth angle which takes Rmax, and the average reflectance of wavelength 400nm -420nm in the azimuth angle which takes Rmin were measured.

(2) Total light transmittance It measured based on JISK7361-1 using the Nippon Denshoku Industries Co., Ltd. product haze meter (NDH5000). A sample was cut out at 4 cm × 4 cm from the center of the film width and measured.

(3) Phase difference A phase difference measuring device (KOBRA-21ADH) manufactured by Oji Scientific Instruments was used. A sample was cut out from the central part in the film width direction at 3.5 cm × 3.5 cm and measured. In each of the slow axis direction and the fast axis direction, the phase difference at a wavelength of 590 nm was measured at incident angles of 0 °, 10 °, 20 °, 30 °, 40 °, and 50 °. In Table 1, R (0 °) is a phase difference at an incident angle of 0 °, and Rmin is an incident angle of 0 °, 10 °, 20 °, 30 °, 40 ° in each of the slow axis direction and the fast axis direction. , The minimum value of the phase difference measured at 50 °.

(Resin used for multilayer laminated film)
Resin A: Polyethylene terephthalate resin with IV = 0.65 B: Polyethylene naphthalate resin with IV = 0.66 C: Copolymer of polyethylene terephthalate with IV = 0.72 (cyclohexanedicarboxylic acid component 20 mol%, spiroglycol component 20 mol % Copolymerized polyethylene terephthalate)
Resin D: Polyethylene terephthalate copolymer with IV = 0.73 (polyethylene terephthalate copolymerized with 33 mol% of cyclohexanedimethanol component)
(Ultraviolet absorber (UVA) used for multilayer laminated film)
UVA_A: 2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol], molecular weight 659
UVA_B: 2,4,6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine, molecular weight 700
(Mixture of resin and UV absorber)
The following amount of resin and ultraviolet absorber were mixed using an extruder.
Resin E: Resin C / UVA_A (90 wt% / 10 wt%)
Resin F: Resin C / UVA_B (90 wt% / 10 wt%)
Resin G: Resin D / UVA_B (90 wt% / 10 wt%)
Method for Measuring IV (Intrinsic Viscosity) Orthochlorophenol was used as a solvent, dissolved at a temperature of 100 ° C. for 20 minutes, and then calculated from the solution viscosity measured at 25 ° C. using an Ostwald viscometer.

Example 1
Resin A was used as the polyester-based resin constituting the A layer, and resin C was used as the polyester-based resin constituting the B layer. Resin A and Resin C were each melted at 280 ° C. with an extruder, passed through five FSS type leaf disk filters, and then discharged with a gear pump (lamination ratio) of resin A / resin B = 27 / While being measured to be 1, the 51-layer feed block (26 layers for A layer and 25 layers for B layer) was alternately joined. Next, after being supplied to a T-die and molded into a sheet, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic application voltage of 8 kV with a wire to obtain an unstretched multilayer laminated film It was. This unstretched multi-layer laminated film was guided to a tenter that grips both ends with clips, and was stretched transversely at 100 ° C. and 5.0 times, followed by heat treatment at 230 ° C. for 10 seconds and 5% widthwise relaxation for 10 seconds. After cooling at 0 ° C., a multilayer laminated film having a thickness of 40 μm (both surface layers 18.5 μm, second layer to 50th layer 59 nm) was obtained.

(Example 2)
Resin A was used as the polyester-based resin constituting the A layer, and resin C was used as the polyester-based resin constituting the B layer. Resin A and Resin C were each melted at 280 ° C. with an extruder, passed through five FSS type leaf disk filters, and then discharged with a gear pump (lamination ratio) of resin A / resin B = 27 / While being measured to be 1, the 51-layer feed block (26 layers for A layer and 25 layers for B layer) was alternately joined. Next, after being supplied to a T-die and molded into a sheet, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic application voltage of 8 kV with a wire to obtain an unstretched multilayer laminated film It was. This unstretched multilayer laminated film was guided to a longitudinal stretching machine, stretched at 100 ° C. and 5.0 times, heat-treated at 230 ° C. for 10 seconds with a tenter, cooled at 100 ° C. for 10 seconds, and then 40 μm thick (both surface layers 18 each). 0.5 μm, 2nd layer to 50th layer 59 nm) was obtained.

(Example 3)
A multilayer laminated film was obtained in the same manner as in Example 1 except that the thickness was 80 μm (both surface layers 38.6 μm, the second layer to the 50th layer 59 nm).

Example 4
Resin A was used as the polyester-based resin constituting the A layer, and resin C was used as the polyester-based resin constituting the B layer. Resin A and Resin C were each melted at 280 ° C. with an extruder, passed through five FSS type leaf disk filters, and then discharged with a gear pump (lamination ratio) of resin A / resin B = 1 / While weighing to be 1, the 267-layer feed block (A layer is 134 layers and B layer is 133 layers) is merged alternately, and then using a 3-layer pinol, the lamination ratio is resin A / resin The A layer was joined to both surface layers so that B = 8.6 / 1. The other conditions were the same as in Example 1. The thickness was 63 μm (both surface layers were 25 μm, the layer thickness was increased from 40 nm to 60 nm in a geometric sequence from the second layer to the 134th layer, To 266th layer to obtain a multilayer laminate film having a geometric progression from 60 nm to 40 nm).

(Example 5)
Resin B was used as the polyester resin constituting the A layer, and Resin D was used as the polyester resin constituting the B layer. Resin A and Resin D were melted at 290 ° C. and 280 ° C. respectively with an extruder, passed through 5 sheets of FSS type leaf disc filters, and the discharge ratio (lamination ratio) was resin A / resin B with a gear pump. While being measured so as to be = 28/1, 51 layer feed blocks (26 layers for A and 25 layers for B) were alternately joined. Next, after being supplied to a T-die and molded into a sheet, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic application voltage of 8 kV with a wire to obtain an unstretched multilayer laminated film It was. This unstretched multilayer laminated film was guided to a tenter that grips both ends with clips, and was stretched transversely at 140 ° C. and 5.0 times, followed by heat treatment at 160 ° C. for 10 seconds and 5% widthwise relaxation for 100 seconds for 10 seconds. After cooling at 0 ° C., a multilayer laminated film with a thickness of 40 μm (both surface layers 18.6 μm, second layer to 50th layer 56 nm) was obtained.

(Example 6)
A multilayer laminated film was obtained in the same manner as in Example 5 except that the thickness was 30 μm (both surface layers were 13.6 μm and the second to 50th layers were 56 nm).

(Example 7)
A multilayer laminated film was obtained in the same manner as in Example 1 except that 80 wt% / 20 wt% of resin C / resin E was used as the polyester-based resin constituting the B layer.
(Example 8)
A multilayer laminated film was obtained in the same manner as in Example 1 except that 80 wt% / 20 wt% of resin C / resin F was used as the polyester resin constituting the B layer.

Example 9
A multilayer laminated film was obtained in the same manner as in Example 4 except that 80% by weight / 20% by weight of resin C / resin E was used as the polyester-based resin constituting the B layer.

(Example 10)
A multilayer laminated film was obtained in the same manner as in Example 4 except that 80% by weight / 20% by weight of resin C / resin F was used as the polyester resin constituting the B layer.

(Example 11)
A multilayer laminated film was obtained in the same manner as in Example 5 except that 95% by weight / 5% by weight of resin D / resin G was used as the polyester resin constituting the B layer.

(Comparative Example 1)
Resin A was melted at 280 ° C. with an extruder, passed through five FSS type leaf disk filters, supplied to a T-die, molded into a sheet, and then subjected to an electrostatic applied voltage of 8 kV with a wire. Then, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. to obtain an unstretched multilayer laminated film. This unstretched multi-layer laminated film was guided to a tenter that grips both ends with clips, and was stretched transversely at 100 ° C. and 5.0 times, followed by heat treatment at 230 ° C. for 10 seconds and 5% widthwise relaxation for 10 seconds. After cooling at 0 ° C., a film having a thickness of 80 μm was obtained.

(Comparative Example 2)
Resin A was used as the polyester-based resin constituting the A layer, and resin C was used as the polyester-based resin constituting the B layer. Resin A and Resin C were each melted at 280 ° C. with an extruder, passed through five FSS type leaf disk filters, and then discharged with a gear pump (lamination ratio) of resin A / resin B = 27 / While being measured to be 1, the 51-layer feed block (26 layers for A layer and 25 layers for B layer) was alternately joined. Next, after being supplied to a T-die and molded into a sheet, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic application voltage of 8 kV with a wire to obtain an unstretched multilayer laminated film It was. This unstretched multilayer laminated film was stretched by 90 ° C and 3.3 times with a longitudinal stretching machine, led to a tenter that grips both ends with clips, and then stretched at 100 ° C and 3.5 times, then at 230 ° C for 10 seconds. After heat treatment and 5% widthwise relaxation and cooling at 100 ° C. for 10 seconds, a multilayer laminated film having a thickness of 40 μm (both surface layers 18.5 μm, second layer to 50th layer 59 nm) was obtained.

(Example 12)
Thickness 64 μm (both surface layers 25 μm, the layer thickness increases from 42 nm to 63 nm in a geometric sequence from the second layer to the 134th layer, and 63 nm in the geometric sequence from the 134th layer to the 266th layer. A multilayer laminated film was obtained in the same manner as in Example 4 except that the layer thickness was reduced from 42 to 42 nm.

(Example 13)
Thickness 64 μm (both surface layers 25 μm, the layer thickness increases from 42 nm to 63 nm in a geometric sequence from the second layer to the 134th layer, and 63 nm in the geometric sequence from the 134th layer to the 266th layer. A multilayer laminated film was obtained in the same manner as in Example 10 except that the layer thickness was reduced from 42 to 42 nm.

(Comparative Example 3)
Resin A was used as the polyester-based resin constituting the A layer, and resin C was used as the polyester-based resin constituting the B layer. Resin A and Resin C were each melted at 280 ° C. with an extruder, passed through five FSS type leaf disk filters, and then discharged with a gear pump (lamination ratio) of resin A / resin B = 1 / While weighing to be 1, the 267-layer feed block (A layer is 134 layers and B layer is 133 layers) is merged alternately, and then using a 3-layer pinol, the lamination ratio is resin A / resin The A layer was joined to both surface layers so that B = 8.6 / 1. Next, after being supplied to a T-die and molded into a sheet, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic application voltage of 8 kV with a wire to obtain an unstretched multilayer laminated film It was. This unstretched multilayer laminated film was stretched 3.3 times at 90 ° C with a longitudinal stretching machine, led to a tenter that grips both ends with clips, and transversely stretched at 100 ° C and 3.5 times, with a thickness of 64 µm (both surface layers respectively) The layer thickness increases from 42 nm to 63 nm in a geometric sequence from 25 μm to the second layer to the 134th layer, and the layer thickness increases from 63 nm to 42 nm in the geometric sequence from the 134th layer to the 266th layer. Reduced) multilayer laminated film was obtained.

  The present invention relates to a UV-cut multilayer laminated film that suppresses rainbow unevenness and achieves thinning and low bleed-out properties while being a polyester film, and a method for producing the same. Moreover, the multilayer laminated film of this invention can be used suitably as a touchscreen base film which forms the polarizer protective film, screen protective film, and transparent conductive layer which are used for a liquid crystal display.

1: Longitudinal direction in the film plane.
2: The width direction in the film plane.
3: In-plane refractive index distribution of the A layer.
4: In-plane refractive index distribution of the B layer.
5: In-plane refractive index difference between A layer and B layer.
6: In-plane refractive index difference between the A layer and the B layer in the longitudinal direction.
7: In-plane refractive index difference in the width direction between the A layer and the B layer.
8: Multilayer laminated film 9 of the present invention: Incident light 10: Slow axis 11: Fast axis 12: Slope angle of incident light in the fast axis direction 13: Slope angle of incident light in the slow axis direction 14: Slow axis direction 15: Fast axis direction 16: Thickness direction 17: Arbitrary direction 18 having a relationship perpendicular to the azimuth 18 in the plane of the polarizing plate or polarizer placed on the viewing side of the multilayer laminated film or display device : Arbitrary direction having a relationship perpendicular to the orientation 17 in the plane of the polarizing plate or polarizer placed on the viewing side of the multilayer laminated film or display device 19: Polarized light placed on the viewing side of the multilayer laminated film or display device Plate or polarizer 20: Vibration direction of linearly polarized light or direction of transmission axis of polarizing plate or polarizer placed on the viewing side of the display device 21: Azimuth angle
22: Multilayer laminated film 23 of the present invention: Direction of Rmax in the film plane 23 ': Azimuth angle (Φ1) of Rmax
24: Polarizing plate or polarizer installed on the viewing side of the display device 25: Direction of taking the transmission axis of the polarizing plate or polarizer installed on the viewing side of the display device 25 ′: Installed on the viewing side of the display device Azimuth angle of transmission axis of polarizing plate or polarizer (Φ2)
26: LED light source 27: second polarizing plate 28: liquid crystal layer 29: first polarizing plate 30: polarizer protective film or retardation film 31: polarizer 32: support 33: metal electrode layer 34: organic light emitting layer 35: Transparent electrode layer 36: Transparent support 37: Polarizing plate or circularly polarizing plate 38: Polarizer protective film or retardation film 39: Polarizer 40: Polarizer protective film or retardation film

Claims (13)

A multilayer laminated film of 51 or more layers in which a polyester resin A and a polyester resin B are alternately laminated, wherein the total light transmittance is 85% or more, the transmittance at a wavelength of 380 nm is 40% or less, and the phase difference is 3000 nm or more. A multilayer laminated film characterized by being:   2. The multilayer laminated film according to claim 1, wherein the phase difference is 3000 nm or more over a range of incident angles from 0 ° to 50 °.   3. The multilayer laminated film according to claim 1, wherein either one or both of the polyester resin A and the polyester resin B contains naphthalenedicarboxylic acid as a dicarboxylic acid component. 4.   The multilayer laminated film according to any one of claims 1 to 3, further comprising an ultraviolet absorber.   The multilayer laminated film according to any one of claims 1 to 4, wherein the ultraviolet absorbent is a triazine ultraviolet absorbent.   The multilayer film according to any one of claims 1 to 5, wherein a film thickness is 15 to 60 µm.   It is used as a polarizer protective film, The multilayer laminated film in any one of Claims 1-6 characterized by the above-mentioned.   The polyester resin A is mainly composed of polyethylene terephthalate, the polyester resin B is composed of terephthalic acid as the dicarboxylic acid component, and ethylene glycol as the diol component. The multilayer laminated film according to any one of claims 1 to 7, wherein the main component is a polyester comprising at least one copolymer component among cyclohexanedimethanol, spiroglycol and isosorbide as a component. The multilayer laminated film according to any one of claims 1 to 8, which is used for a display device. It is used for the display apparatus which has a polarizing plate and / or a polarizer which satisfy | fills following formula (6), and satisfies following formula (7) and (8), In any one of Claims 1-9 characterized by the above-mentioned. The multilayer laminated film as described.
0 ° ≦ | Φ1-Φ2 | <45 ° (6)
Rmax ≧ 20% (7)
Rmax−Rmin> 5% (8)
(Where Φ1 is the azimuth angle taking Rmax in the plane of the multilayer laminated film, and Φ2 is the azimuth angle of the transmission axis of the polarizing plate or polarizer placed on the viewing side of the display device. The laminated film is irradiated with linearly polarized light at an incident angle of 0 °, and with the incident optical axis of the multilayer laminated film as the center, the arbitrary azimuth direction on the multilayer laminated film surface is 0 °, and linearly polarized light at intervals of 5 ° up to 180 °. Is the maximum value of the maximum reflectance in the wavelength range of 381 nm to 420 nm at each azimuth angle measured by half-rotating the azimuth angle, and Rmin is the maximum in the wavelength range of 381 nm to 420 nm at the azimuth angle orthogonal to Φ1. Reflectivity.)   The laminated body which provided the layer which contains a ultraviolet absorber in the multilayer laminated film in any one of Claims 1-10.   The liquid crystal display device using the multilayer laminated film in any one of Claims 1-10, or the laminated body of Claim 11.   The organic electroluminescence display using the multilayer laminated film in any one of Claims 1-10, or the laminated body of Claim 11.

Images