JP2019091040A - Laminated film - Google Patents

Abstract

To provide a laminated film which uses properties of reflection anisotropy while using light reflection of a multilayer laminated structure, is approximately free from coloration of the film, can protect deterioration in a display content over a long period of time, and achieves both high transparency and long-wavelength ultraviolet cut property.SOLUTION: In a laminated film in which 51 or more layers of A layers containing a thermoplastic resin A as a main component and B layers containing a thermoplastic resin B having a different refractive index from the thermoplastic resin A as a main component are alternately laminated, in absolute light transmittance determined by irradiation with linear polarization (X wave) oscillating in a film orientation direction and absolute light transmittance determined by irradiation with linear polarization (Y wave) oscillating in a direction perpendicular to the orientation direction, one absolute light transmittance is 10% or more at a wavelength of 400 nm, is 70% or more at a wavelength of 420 nm, and is 80% or more at a wavelength of 440 nm, and the other absolute light transmittance is less than 10% at the wavelength of 400 nm, is less than 70% at the wavelength of 420 nm and is 80% or more at the wavelength of 440 nm.SELECTED DRAWING: None

Description

  The present invention relates to a highly transparent laminated film in which the reflection hue is suppressed while having long wavelength ultraviolet ray cut properties.

  Thermoplastic resin films, in particular polyester films, have excellent mechanical properties, electrical properties, dimensional stability, transparency, chemical resistance, etc. And are widely used as base films. In particular, in the fields of automobiles, construction materials and electronics, there is a demand for polyester films that cut ultraviolet light.

  A polarizer protective film, retardation film, etc. are used as films for optics in various displays, such as a flat panel display, a touch panel, a car-mounted panel display, and a digital signage. In a liquid crystal display, light from a backlight is converted into linearly polarized light through a uniaxially oriented polarizer (PVA), and is transmitted to the front of the display when liquid crystal molecules are oriented in a certain direction. Since organic molecules such as a polarizer and liquid crystal molecules inside a liquid crystal display are degraded by ultraviolet rays penetrating from the outside, a film positioned on the viewing side of the polarizer is required to have ultraviolet ray cutting properties. Moreover, in organic EL displays, organic molecules corresponding to light emitting elements tend to be decomposed or degraded by receiving light having a wavelength shorter than the wavelength emitted by the molecules. There is a need to cut light in a broad wavelength range, including energy visible light regions.

  In general, a formulation in which a UV absorber is added to a resin is used as a formulation for imparting UV cut properties to a polyester film. (Patent Document 1) However, when achieving ultraviolet cut by the method of adding an ultraviolet absorber, bleed out occurs in the vicinity of a die or a vacuum vent at the time of film deposition depending on the type and addition amount of the ultraviolet absorber. . As a result, film formation process contamination occurs to cause defects in the film, and a problem arises in that the quality of the film itself is impaired, such as a decrease in the concentration of the ultraviolet absorber addition and a reduction in cutting performance. In order to meet the recent needs in the display field such as cost reduction, low power consumption, and long life, thin films showing UV cut properties equal to or higher than current optical films are required, but the absorption performance is not limited to films. High concentration of UV absorbers can not be avoided because it depends on the product of the thickness of the film and the added concentration, and it is due to the significant film deposition equipment contamination or the absorber deposition on the film surface after the endurance test under severe conditions. There is a problem that the deterioration in quality is remarkable.

  A method is used in which light reflection by the laminated film and absorption by the ultraviolet absorber are used in combination as a formulation for achieving the ultraviolet ray cutting property even in a thin film while reducing the amount of the ultraviolet absorber added to the resin. (Patent Documents 2 and 3) As a result, the reflection helps to cut the light beam, and the optical path length of the light beam reflected is increased by the effect of the interference reflection. Therefore, the same absorption performance can be obtained even in the case of low concentration absorber addition. It will be possible to achieve.

Unexamined-Japanese-Patent No. 2013-210598 JP, 2016-215643, A International Publication No. 2016/148141

  However, when the reflection band is shifted to the high energy visible light region at a slightly longer wavelength position than the ultraviolet light region, the light from the high energy visible light region is reflected to the front of the laminated film, so the laminated film itself becomes bluish and transparent And lose the clear display when mounted on the display. In display applications where high image quality is a high-end characteristic, since highly delicate and highly transparent color display is regarded as the most important, unwanted coloration must be avoided.

  As a result of intensive studies by the present inventors, the laminated film exhibiting reflective characteristics is strongly stretched and oriented in an arbitrary direction based on the multilayer laminated structure, and by expressing the reflection anisotropy, while suppressing the reflection hue as much as possible, It has been found that light rays up to the visible short wavelength region on the long wavelength side can be cut sharply. Specifically, the reflection anisotropy refers to the property that the wavelength band to be reflected differs between the case where polarized light vibrating in the orientation direction is irradiated and the case where polarized light vibrating in the direction orthogonal to the orientation direction is irradiated. It has been found that the ray cuttability obtained by irradiating polarized light is steeper than when irradiated with natural light.

  Since light obtained by transmitting through a polarizing plate including a polarizer in which PVA is uniaxially oriented is generally linearly polarized light, it transmits only polarized light in a specific direction. At this time, by arranging the transmission axis direction of the polarizing plate used for the display and the film orientation axis on the viewing side (upper side) of the polarizing plate so as to be parallel or perpendicular, light rays transmitted from the back of the display Show the property of cutting light to longer wavelength side under the influence of On the other hand, since the light beam reflected on the film surface is natural light, the reflection hue can be suppressed more than expected from the wavelength of linearly polarized light.

  Therefore, it is an object of the present invention to provide a highly transparent laminated film without coloring while cutting the light to the high energy visible light region by using the above-described feature of reflection anisotropy by stretching.

The present invention has the following configuration. That is,
A laminated film in which 51 layers or more of a layer A mainly composed of a thermoplastic resin A and a layer B mainly composed of a thermoplastic resin B having a refractive index different from that of the thermoplastic resin A are alternately laminated,
Absolute light transmittance determined by irradiating linearly polarized light (X wave) vibrating in the film orientation direction, and absolute light beam determined by irradiating linearly polarized light (Y wave) vibrating in the direction perpendicular to the orientation direction Among the transmittances, one absolute light transmittance is 10% or more at a wavelength of 400 nm, 70% or more at a wavelength of 420 nm, and 80% or more at a wavelength of 440 nm, and the other absolute light transmittance is 10% at a wavelength of 400 nm The laminated film which is less than 70% at a wavelength of 420 nm and 80% or more at a wavelength of 440 nm.

  In the laminated film of the present invention, the reflection color tone is suppressed while sufficiently cutting light in a wide wavelength range from the ultraviolet region to the high energy visible light region, and when mounted on a display, the image is highly transparent and high quality. There is an effect that can be displayed.

It is a schematic diagram showing the reflection zone of a spectrum reflection spectrum. It is a schematic diagram showing another form of the reflection zone of a spectrum reflection spectrum. It is a schematic diagram which shows the spectral transmission spectrum at the time of irradiating either linearly polarized light of X wave or Y wave with respect to the laminated film which shows reflection anisotropy. It is a schematic diagram which shows the one aspect | mode of a head-up display which has a polarizer which can utilize suitably the laminated | multilayer film of this invention. It is a schematic diagram which shows the one aspect | mode of a head-up display which has a polarizer which can utilize suitably the laminated | multilayer film of this invention.

  Hereinafter, the laminated film of the present invention will be described in detail.

  In the laminated film of the present invention, 51 layers or more of layers A consisting mainly of thermoplastic resin A and layers B consisting mainly of thermoplastic resin B having a refractive index different from the thermoplastic resin A are laminated alternately. A laminated film, which emits an absolute light transmittance determined by irradiating linearly polarized light (X wave) vibrating in the film orientation direction, and irradiates linearly polarized light (Y wave) vibrating in a direction perpendicular to the orientation direction Among the absolute light transmittances to be determined, one absolute light transmittance is 10% or more at a wavelength of 400 nm, 70% or more at a wavelength of 420 nm, 80% or more at a wavelength of 440 nm, and the other absolute light transmittance is It is necessary to be less than 10% at a wavelength of 400 nm, less than 70% at a wavelength of 420 nm, and 80% or more at a wavelength of 440 nm.

  Examples of the thermoplastic resin used in the present invention include polyethylene, polypropylene, poly (1-butene), poly (4-methylpentene), polyisobutylene, polyisoprene, polybutadiene, polyvinylcyclohexane, polystyrene, poly (α-methyl). Polyolefin resins represented by styrene), poly (p-methylstyrene), polynorbornene, polycyclopentene etc., polyamide resins represented by nylon 6, nylon 11, nylon 12, nylon 66 etc., ethylene / propylene copolymer, Ethylene / vinylcyclohexane copolymer, ethylene / vinylcyclohexene copolymer, ethylene / alkyl acrylate copolymer, ethylene / acrylic methacrylate copolymer, ethylene / norbornene copolymer And copolymer resins of vinyl monomers represented by ethylene / vinyl acetate copolymer, propylene / butadiene copolymer, isobutylene / isoprene copolymer, vinyl chloride / vinyl acetate copolymer, etc., polyacrylate, polymethacrylate, polymethylmethacrylate, polyacrylamide, polyacrylonitrile Acrylic resins typified by: polyester resins represented by polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2, 6-naphthalate etc., poly resins represented by polyethylene oxide, polypropylene oxide, polyacrylene glycol Ether resin, diacetyl cellulose, triacetyl cellulose, propionyl cellulose, butyryl cellulose Cellulose, acetyl propionyl cellulose, cellulose ester resins represented by nitrocellulose, biodegradable polymers represented by polylactic acid, polybutyl succinate etc., and others, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, Polyacetal, polyglycolic acid, polycarbonate, polyketone, polyethersulfone, polyetheretherketone, modified polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide, polysiloxane, tetrafluoroethylene resin, trifluoroethylene resin, trifluoride resin Chlorinated ethylene resin, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride and the like can be mentioned.

  The thermoplastic resin used in the present invention is preferably a synthetic polymer, and more preferably a polyolefin, acrylic, polyester, cellulose ester, polyvinyl butyral, polycarbonate, or polyether sulfone. Among them, polyethylene, polypropylene, polymethyl methacrylate, polyesters and triacetyl cellulose are particularly preferable. In addition, these may be used alone or as two or more polymer blends or polymer alloys.

It is necessary that the thermoplastic resin B is not the same thermoplastic resin as the thermoplastic resin A, but a resin having a different refractive index. When realizing ray cutting by reflection, the wavelength of the reflected ray is uniquely determined according to the layer thickness of the resin to be laminated and the equation (1) based on the refractive index difference of two different thermoplastic resins. (In the formula (1), n _A and n _B represent the refractive index of the thermoplastic resin A and the thermoplastic resin B, respectively, and d _A and d _B each represent the layer containing the thermoplastic resin A as a main component, and the thermoplastic resin Refers to the layer thickness of the layer mainly composed of B. k is an arbitrary natural number.) Therefore, when a thermoplastic resin having the same refractive index is used, no light reflection at the thermoplastic resin interface occurs. . In order to reflect light of a specific wavelength, two parameters of resin layer thickness and refractive index difference should be precisely controlled, so it is necessary to unambiguously determine only the numerical range of refractive index difference. Although it is difficult, the difference in refractive index between the thermoplastic resin A and the thermoplastic resin B needs to be 0.01 or more, more preferably 0.03 or more, and still more preferably 0.05 or more. On the other hand, the upper limit of the difference in refractive index between the thermoplastic resin A and the thermoplastic resin B is not particularly limited as long as the effects of the present invention are not impaired, but the viewpoint of adhesion at the layer interface of alternately laminated thermoplastic resins From, it will be 0.4.

  Moreover, in addition to the difference in refractive index, it is preferable that these different thermoplastic resins A and thermoplastic resins B have different heat characteristics at the same time. Different thermal properties refer to different melting points as well as glass transition temperatures in differential scanning calorimetry (DSC). The difference in the melting point and the glass transition temperature makes it possible to highly control the orientation state of each layer in the process of stretching and heat treatment of the laminated film. By highly controlling the orientation state, it is possible to control the refractive index in the in-plane and in-plane directions of each thermoplastic resin layer, and to control the wavelength of the reflected light beam. In particular, it is preferable that the thermoplastic resin A and the thermoplastic resin B differ by 0.1 ° C. or more in the glass transition temperature and the melting point which affect the orientation state of the resin in the stretching step. However, in view of the accuracy of temperature control in the apparatus, the melting point and the glass transition temperature preferably differ by 1 ° C. or more, more preferably 3 ° C. or more, and still more preferably 5 ° C. or more. On the other hand, the upper limit of the difference between the glass transition temperature and the melting point of the thermoplastic resin A and the thermoplastic resin B is not particularly limited as long as the effects of the present invention are not impaired. It becomes.

  In some cases, only one of the thermoplastic resin A and the thermoplastic resin B may exhibit a glass transition temperature and a melting point. In this case, although the temperature difference can not be calculated, the thermal characteristics of the resin may be interpreted as being different. On the other hand, using a resin that does not exhibit a glass transition temperature or a melting point as the thermoplastic resin A and the thermoplastic resin B implies that the laminated film can not be stretched due to adhesion to the roll or clip in the stretching step It is not preferable in the present development which requires a biaxial stretching step.

  Among the thermoplastic resins described above, at least one of the thermoplastic resin A and the thermoplastic resin B is preferably made of a polyester resin from the viewpoints of strength, heat resistance, transparency and versatility. Below, the aspect of the polyester-type resin which is a preferable film base is described.

  The polyester in the present invention is a condensation polymer obtained by polymerization from a monomer containing an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid and a diol as main components. As known methods for industrial production of polyester, transesterification (transesterification method) or direct esterification reaction (direct polymerization method) is used. 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 dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenyl sulfone dicarboxylic acid etc. can be mentioned. Examples of aliphatic dicarboxylic acids include adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, 1,4-cyclohexanedicarboxylic acid, and their ester derivatives. Among these, terephthalic acid and 2,6-naphthalenedicarboxylic acid exhibiting a high refractive index are preferably used.

  Also, as the diol component, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 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 can be mentioned. Among them, ethylene glycol is preferably used.

  Furthermore, polyester resins include, for example, polyethylene terephthalate and copolymers thereof, polyethylene naphthalate and copolymers thereof, polybutylene terephthalate and copolymers thereof, polybutylene naphthalate and copolymers thereof, and further polyhexamethylene Terephthalate and its copolymer, polyhexamethylene naphthalate and its copolymer, etc. can also be used. At this time, it is preferable that one or more types of the above-mentioned dicarboxylic acid component and diol component are copolymerized as a copolymerization component which constitutes a copolymer.

  In the present invention, “laminated alternately” means that the thermoplastic resin A constituting the A layer and the thermoplastic resin B constituting the B layer are laminated in a regular arrangement in the thickness direction, BA) refers to a state in which resins are laminated according to a regular arrangement of n, B (AB) n, or A (BA) nB (n is a natural number). By alternately laminating the resins having different thermal properties in this manner, it is possible to highly control the orientation state of each layer in the step of stretching and heat treating the laminated film. When forming a laminated film having such a layer configuration, the thermoplastic resin A and the thermoplastic resin B are fed from different flow paths using two or more extruders, and a multi-manifold type feed which is a known laminating apparatus It can be made to stack using a block or a static mixer. In particular, in order to obtain the configuration of the present invention efficiently, a method using a feed block having fine slits is preferable in order to realize highly accurate lamination. When forming a laminate using a slit type feed block, the thickness of each layer and its distribution change the length and width of the slit to incline the pressure loss, or any comb in the feed block This can be achieved by finely controlling the temperature in the section. The length of the slit is the length of the comb-tooth portion forming a flow path for alternately flowing the layer A and the layer B in the slit plate. In the present invention, in order to simplify the following description, the thermoplastic resin A is described on the assumption that it has a configuration of A (BA) n (n is a natural number) located in the outermost layer. In the case of B (AB) n (n is a natural number), it is sufficient if the thermoplastic resin A and the thermoplastic resin B are interchanged and interpreted.

  In the case of the configuration of A (BA) n or B (AB) n described above, the thermoplastic resin (thermoplastic resin A in the former case, thermoplastic resin B in the latter case) is located on the outermost surface of the laminate. It is preferable that it is a thermoplastic resin which shows crystallinity. In this case, the laminated film can be obtained by the same film forming step as the single film film containing the thermoplastic resin exhibiting the crystallinity as a main component, which is preferable. When the thermoplastic resin A is made of a non-crystalline resin, when a biaxially stretched film is obtained in the same manner as a general sequential biaxially stretched film described later, adhesion to manufacturing equipment such as rolls and clips Problems such as poor film formation and deterioration of surface condition may occur.

  In addition, the configuration of A (BA) nB, that is, the configuration in which the A layer is located on one outermost surface and the B layer is located on the opposite outermost surface may be employed. In this case, when the thermoplastic resin A and / or the thermoplastic resin B is a non-crystalline resin, the same problem in film formation due to the non-crystalline resin as described above may occur. It is preferable that both the resin A and the thermoplastic resin B be a crystalline thermoplastic resin.

  Summarizing the above, as the thermoplastic resin A, it is preferable to use polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, which is a polyester type having crystallinity. Above all, it is more preferable to use polyethylene terephthalate or polyethylene naphthalate from the viewpoint that the crystallization speed is not too fast in the drawing process and the laminated structure is easily realized with high accuracy. On the other hand, it is preferable that the thermoplastic resin B is a polyester resin containing the same basic skeleton as the thermoplastic resin A also from the viewpoint of adhesion and lamination with the thermoplastic resin A. Here, the basic skeleton is a repeating unit constituting a resin, and in the case of polyethylene terephthalate, ethylene terephthalate and in the case of polyethylene naphthalate, ethylene naphthalate is the basic skeleton. By having the same skeleton, lamination accuracy is high, and delamination at the lamination interface is less likely to occur. With respect to polyethylene terephthalate, while polyethylene naphthalate is likely to orient the polymer in the surface direction, it is more likely to cause delamination, and therefore it is most preferable to use polyethylene terephthalate as the basic skeleton from the viewpoint of laminated film.

  In the case where the thermoplastic resin A and the thermoplastic resin B have polyethylene terephthalate as a basic skeleton, the thermoplastic resin B is different from the copolymerizable component in which the copolymer component which does not constitute the basic skeleton is contained in the thermoplastic resin A Alternatively, it is preferable that the amount different from the amount of the copolymerization component in the thermoplastic resin A is contained to such an extent that it does not become a main component. When polyethylene terephthalate is used as a basic skeleton, preferred copolymer components include cyclohexanedimethanol, bisphenol A ethylene oxide, spiroglycol, isophthalic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, polyethylene glycol 2000, m-polyethylene glycol 1000, m-polyethylene glycol 2000, m-polyethylene glycol 4000, m-polypropylene glycol 2000, bisphenylethylene glycol fluorene (BPEF), fumaric acid, acetoxybenzoic acid and the like. Among them, it is preferable to copolymerize spiro glycol, isophthalic acid and 2,6-naphthalene dicarboxylic acid. When spiroglycol is copolymerized, the glass transition temperature difference with polyethylene terephthalate is small, so it is difficult to be overstretched at the time of molding, and delamination is unlikely to occur. In addition, when isophthalic acid is copolymerized, the crystallinity can be greatly reduced because the position of the functional group in the benzene ring is not linear, while it exhibits high refractive index overall because of high planarity. Is possible.

  In the laminated film of the present invention, the layer A containing the above-described thermoplastic resin A as a main component, and 51 layers containing B as a main component containing a thermoplastic resin B having a refractive index different from that of the thermoplastic resin A are alternately included. It is necessary to be laminated above. By alternately laminating different thermoplastic resins, it is possible to express interference reflection which can reflect a light beam of a specific wavelength designed based on the relationship between the difference in refractive index of each layer and the layer thickness. In particular, by targeting the wavelength band that generates interference reflection to the ultraviolet light region or the high energy visible light region of wavelengths 380 nm to 440 nm, the laminated film itself has ultraviolet light cutting ability and / or high energy visible light cutting ability by reflection. It becomes possible to grant. If the number of laminations is less than 51, high reflectance can not be obtained over a wide wavelength band, and sufficient ray cutting can not be realized. In addition, in the case of a film laminated alternately by 51 or more layers, each resin is uniformly distributed as compared with a film laminated by several layers to several tens of layers, so that stable film forming properties and mechanical properties are obtained. It becomes possible. Furthermore, as the number of layers increases, there is a tendency to be able to suppress the growth of orientation in each layer, and it is easy to control optical properties such as refractive index by alternately laminating many layers. The number of layers is preferably 100 or more, more preferably 200 or more. There is no upper limit to the number of layers, but as the number of layers increases, this leads to an increase in manufacturing cost accompanying an increase in the size of the manufacturing apparatus and a deterioration in handling due to the increase in film thickness. In particular, when the film thickness becomes thick, when the thermoplastic resin is made of a crystalline polyester resin and exhibits birefringence, the absolute thickness of the layer A increases to cause rainbow marks when used as a member for image display Therefore, 2000 layers or less are practically suitable. Birefringence refers to the property that the refractive index in the direction perpendicular to the drawing direction and in the plane perpendicular to the drawing direction and in the direction perpendicular to the drawing surface show numerical values different from each other through the drawing process. It is also called "rate anisotropy".

  The laminated film of the present invention has an absolute light transmittance determined by irradiating linearly polarized light (X wave) oscillating in the film orientation direction and linearly polarized light (Y wave) oscillating in the direction perpendicular to the orientation direction. It is necessary to have a difference. The orientation direction of the laminated film is mainly influenced by the size of the draw ratio in the longitudinal direction and the width direction of the film in the biaxial stretching process described later, but the complex behavior due to the shrinkage process of the film in the heat treatment and cooling process. The stretching direction is not necessarily the orientation direction in general. Therefore, in the present invention, the orientation direction is determined by the numerical value of the orientation angle obtained by the automatic birefringence device KOBRA-AD series which can measure the orientation direction by the optical method of Oji Scientific Instruments Co., Ltd. The direction indicated by the numerical value of the orientation angle is defined as the X-axis direction, and the direction perpendicular to the orientation direction is defined as the Y-axis direction.

  Linearly polarized light refers to light oscillated in a specific plane direction including the oscillation direction of an electric field, which is extracted from natural light that is an electromagnetic wave uniformly distributed in any direction. In the laminated film of the present invention, it is important to use the linearly polarized light extracted from the natural light emitted from the light source through the linear polarizer in the spectrophotometer because the light transmittance in the state where the linearly polarized light is irradiated is important. I assume. Typical linear polarizers include polyvinyl alcohol (PVA) -iodine alignment film, "Polaroid" (registered trademark), polarized Nicol prism, etc. In the present invention, Hitachi High-Tech Science Co., Ltd. The linear polarization obtained through the linear polarization attachment attached to the spectrophotometer U-4100 is used.

  The laminated film of the present invention has an absolute light transmittance determined by irradiating linearly polarized light (X wave) vibrating in the film orientation direction and linearly polarized light (Y wave) vibrating in the direction perpendicular to the orientation direction. Among them, one absolute light transmittance is 10% or more at wavelength 400 nm, 70% or more at wavelength 420 nm, 80% or more at wavelength 440 nm, and the other absolute light transmittance is less than 10% at wavelength 400 nm It is necessary to be less than 70% at 420 nm and 80% or more at a wavelength of 440 nm. Although the method for the absolute light transmittance to indicate the above numerical value is not particularly limited, utilization of light interference reflection derived from an alternate multilayer structure of laminated films and light capable of absorbing light in the wavelength band Use of an absorbent etc. are mentioned.

  We describe the light reflection from the alternating multilayer structure of laminated films that can be utilized in the present invention. By alternately laminating thermoplastic resin layers having different refractive indices as in the laminated film of the present invention, a specific wavelength can be obtained according to the layer thickness design of each layer and the refractive index difference between two thermoplastic resins. It is possible to reflect light in the band. As for layer thickness design, it is possible to change the thickness distribution of the laminated layer to expand / contract the wavelength band to be reflected or to improve the light reflectance, and to design the cut end of the reflection band sharply or gently It also becomes possible to design. Moreover, it is also possible to shift freely by changing the thickness while keeping the lamination ratio of the two types of thermoplastic resins constituting the laminated film constant. When controlling the thickness distribution of the laminated layer and designing the cut end of the reflection band to be sharp, the sharp cut is superior to the case where general ultraviolet light absorbers and dyes such as dyes and pigments are added. Since it can be realized and an undesired visible light cut can be prevented, it can be preferably used for a material for which a narrow band and a selective light cut are required.

  As the layer thickness distribution in the laminated film of the present invention, the layer thickness distribution increasing or decreasing from one side to the opposite side in the thickness direction of the film, or the layer thickness from one side of the film to the film center Preferably, the layer thickness distribution decreases after increasing the layer thickness, or the layer thickness distribution decreases after decreasing the layer thickness from one side of the film to the center of the film. As a method of changing the layer thickness distribution, linear, equal ratio, continuous change such as difference number sequence, or 10 to about 50 layers have almost the same layer thickness, and the layer thickness changes in a step shape Preferred. Since the light reflectance of the laminated film at a specific wavelength increases as the number of layers having the same thickness increases, it is most preferable that the layer thickness distribution includes a plurality of inclined distributions of increase and decrease of the layer thickness.

  In the biaxially stretched laminated film, when the constituting thermoplastic resin is a resin exhibiting birefringence, it shows different refractive indexes in the direction of orientation in the plane of the laminated film, the direction orthogonal thereto, and the thickness direction. When the thermoplastic resin A and the thermoplastic resin B which are alternately laminated show different birefringence in the stretching plane through the biaxial stretching step, two thermoplastic resins in the orientation direction and the direction orthogonal thereto Since differences in refractive index between resins occur, the sharp cut characteristics of the reflection band, the reflection end, and the profile of the reflection band change. These in-plane refractive index differences are determined depending on the type of thermoplastic resin to be selected, but in addition, thermal characteristics such as glass transition temperature of thermoplastic resin, temperature conditions at biaxial stretching, stretching It depends on various conditions such as magnification.

  For example, it is assumed that polyethylene terephthalate in which the thermoplastic resin A exhibits birefringence as the type of thermoplastic resin and polyethylene terephthalate in which the thermoplastic resin B copolymerizes spiroglycol exhibiting no orientation is used. After biaxial stretching, only the thermoplastic resin A shows an in-plane refractive index difference. In this case, only the long wavelength side of the reflection band shifts and changes, and the width of the reflection band tends to change. In addition, when using polyethylene terephthalate obtained by copolymerizing isophthalic acid which exhibits slight birefringence after the biaxial stretching process as the thermoplastic resin B, not only the cut end of the long wavelength of the reflection band but also the cut of the short wavelength The edge also shows a tendency to shift change. Thus, the state of the shift of the end of the reflection wavelength band differs depending on the combination of thermoplastic resins having different birefringence. The reflection band, the short wavelength end, and the long wavelength end as described herein refer to the portion shown in FIG.

  In the film forming step of the laminated film of the present invention, strongly stretching the laminated film in a specific direction can increase the in-plane refractive index difference of the laminated film, and the orientation angle is uniform over the entire laminated film surface. It is preferable because it is easy to become. When a laminated film having a uniform orientation angle is mounted on a display, lamination is performed so that the polarized light obtained by transmitting light from the inside of the display through the polarizing plate has the same orientation direction or an orthogonal relationship with the alignment direction Even when the retardation of the laminated film is within the range of 300 nm to 3000 nm which is said to easily cause a decrease in visibility such as rainbow unevenness by laminating the film, the orientation angle in the film plane is Since there is no variation, problems such as rainbow unevenness will not occur.

  In particular, the orientation angle of the laminated film is strongly stretched in the biaxial stretching step to have an orientation angle in the longitudinal direction or the width direction of the film, and the productivity and the visibility in roll lamination when the film is combined with the display member It is preferable from the viewpoint of Generally, in the case of biaxial stretching, since the resin tends to be oriented in the direction in which the film is stretched more strongly in the stretching in the longitudinal direction or the width direction, the orientation angle has an orientation angle in the longitudinal direction or the width direction It is necessary that the draw ratio in one of the longitudinal direction and the width direction be higher than the draw ratio in the other. As the orientation angle of the laminated film, it is preferable that an angle formed by the direction of higher stretching (direction of high draw ratio) and the orientation direction is 10 ° or less among the stretching directions in the longitudinal direction and width direction of the laminate film. More preferably, it is 5 degrees or less, More preferably, it is 3 degrees or less. When the angle formed by the orientation angle of the laminated film and the stronger stretching direction (direction in which the stretching ratio is high) exceeds 10 °, the orientation direction varies within the display surface, although it depends on the size of the display to be bonded. In addition, rainbow unevenness may be observed, and the polarization state of light from the backlight may be changed to impair polarization performance, which may be undesirable. The direction in which the film is strongly stretched can be determined from the respective stretching magnifications of the longitudinal stretching process and the transverse stretching process described in the film forming method described later. Further, in addition to the general film forming method in the present invention described later, after the stretching in the longitudinal direction and the stretching in the width direction are performed, a second longitudinal direction and / or a second width direction stretching process are further performed. It is also possible to carry out the longitudinal stretching process and / or the second transverse stretching process, etc., after performing only the stretching in the transverse direction. In that case, in the former, a width direction obtained by multiplying the longitudinal total draw ratio obtained by multiplying the draw ratio in the longitudinal direction by the draw ratio in the second longitudinal direction, the draw ratio in the width direction, and the draw ratio in the second width direction Comparison of total draw ratio In the latter case, the strong draw axis direction is grasped by comparison of the draw ratio in the longitudinal direction and the draw ratio in the width direction with the draw ratio in the second width direction. It is possible.

  The laminated film of the present invention has an absolute light transmittance of 10% at a wavelength of 400 nm, of the polarized light (X wave) vibrating in the film orientation direction or the polarized light (Y wave) vibrating in the direction orthogonal thereto. It is necessary that the wavelength be less than 70% at a wavelength of 420 nm and 80% or more at a wavelength of 440 nm. The laminated film of the present invention can not be sufficiently cut in the ultraviolet region and high energy visible light when it is irradiated with natural light, but only by applying linearly polarized X-wave or Y-wave vibrating in a specific direction. It has the most important technical features in that the cuttability and high energy visible light cuttability (hereinafter referred to as long wavelength ultraviolet ray cuttability) are exhibited. The schematic diagram of the spectral transmission spectrum at the time of irradiating each linearly polarized light to the laminated film of this invention is described in FIG. By irradiating linearly polarized light vibrating in a direction parallel or perpendicular to the orientation angle of the laminated film, the spectral transmission spectrum of one linearly polarized light is shifted to a longer wavelength side than the spectral transmission in the case of natural light irradiation. The spectral transmission spectrum when irradiated with the other linearly polarized light shows sharp cutability while shifting to a shorter wavelength side.

  The laminated film of the present invention was mounted for display use when the absolute light transmittance of polarized light on the side capable of exhibiting long-wavelength ultraviolet cuttability is not less than 10% at 400 nm when X-wave or Y-wave linearly polarized light is applied. In such a case, the liquid crystal display can not effectively prevent the deterioration of the liquid crystal layer and the polarizer inside, and the display having a light emitting element such as an organic EL display can not effectively prevent the deterioration and degradation of the light emitting layer. In particular, for displays used in outdoor applications, when the ultraviolet region of wavelength 380 nm or less is not completely cut, sufficient image display can not be performed over a long period of time, and luminance degradation of the image display element or polarizer deterioration in image display occurs. It is not preferable because color tone changes etc. occur and visibility deteriorates. Therefore, among the X wave and the Y wave, a wavelength cut property is required such that the absolute light transmittance at a wavelength of 400 nm of polarized light exhibiting ultraviolet ray cut property on the longer wavelength side is less than 10%. The absolute light transmittance at a wavelength of 400 nm is preferably 5% or less, more preferably 3% or less. Of course, the best condition is that it be as close as possible to 0%. Furthermore, in order to achieve high transparency and high image quality, sharp ray cut (sharp cut) is required to minimize the cut property of visible light, and the absolute ray transmittance at a wavelength of 420 nm is less than 70%. By setting the absolute light transmittance at a wavelength of 440 nm to 80% or more, the most effective clear image can be displayed without the laminate film itself being strongly colored. Further, in the case of the organic EL display, it is possible to effectively cut only ultraviolet light and high energy visible light which are harmful to organic molecules constituting the display without affecting the emission wavelength of the blue light emitting element. The absolute light transmittance at a wavelength of 420 nm is more preferably 60% or less, still more preferably 50% or less. The absolute light transmittance at a wavelength of 440 nm is preferably 85% or more, more preferably 90% or more.

  On the other hand, the absolute light beam transmittance when irradiating linearly polarized light on the side different from the above among X waves or Y waves is 10% or more at 400 nm, 70% or more at 420 nm, and 80% or more at 440 nm It is necessary to show In the case of using the reflection by the alternate layered structure, the reflected external light beam is directly viewed. At this time, light rays that can be reflected and visually recognized are natural light from external light, and reflected rays of linearly polarized light in all directions in the plane are added together to show an averaged property. In order to obtain a highly transparent laminated film while exhibiting long wavelength ultraviolet ray cut properties, the wavelength band of reflected light to be recognized must not be strong in the visible light region, so a straight line exhibiting the above-mentioned long wavelength side ultraviolet ray cut off property. When the absolute light beam transmittance when irradiated with linearly polarized light different from the polarized light shows ultraviolet ray cuttability on the shorter wavelength side, the property that the long wavelength UV cuttability weakens as average is required. Specifically, the absolute light transmittance at a wavelength of 400 nm may be 10% or more, preferably 30% or more, and more preferably 50% or more. The absolute light transmittance at a wavelength of 420 nm is preferably 80% or more, more preferably 90% or more. The absolute light transmittance at a wavelength of 440 nm is preferably 90% or more. If it is a laminated film having different light ray cut properties when irradiated with two types of polarized light orthogonal to each other, deterioration of the contents of the display is prevented more than a film having a conventional laminated structure, and long wavelength ultraviolet ray cut property is effective. Since the reflection hue can be minimized while being used as it is, it is very highly transparent, and it is possible to make the image display clearer when the display is not displayed.

  The laminated film of the present invention preferably has a maximum relative light transmittance of 10% or less at a wavelength of 300 nm or more and less than 380 nm. The relative light transmittance is a light transmittance determined when natural light is used as a light source, and a detailed measurement method will be described later. In the ultraviolet region of 300 nm or more and less than 380 nm, as described above, it is a wavelength band that greatly contributes to the deterioration of the important parts of image display such as polarizers, liquid crystal molecules, and light emitting molecules inside the display. Is more preferably 5% or less, more preferably 2% or less. Of course, the best condition is that it be as close as possible to 0%.

  The laminated film of the present invention has a cutoff wavelength Λ of 400 nm or more and 440 nm or less at a wavelength of 400 nm or more, an absolute value of a reflected hue b * value of 10 or less, and a cutoff wavelength Λ of a wavelength of 400 nm or more and a reflected hue b * It is preferable that the value satisfy the relational expression of equation (2). By satisfying the formula (2), it is possible to reduce the coloring by the reflected light as much as possible, and to strongly show both the long wavelength ultraviolet ray cuttability and the high transparency which are the features of the present invention.

b *> − 0.805Λ + 320 formula (2)
The cutoff wavelength in the present invention refers to the ultraviolet region as shown in FIGS. 1 and 2 in the absolute reflection spectrum when the laminated film is irradiated with linearly polarized light having an absolute light transmittance of less than 10% at 400 nm. Among the numerical values indicating the half value of the reflectance maximum value of the reflection band, it refers to the wavelength located at the longest wavelength position. The reflection band refers to a series of bands in which the absolute value of the light reflectance is 12% or more over the wavelength of 10 nm or more. As shown in FIG. 2, when there are a plurality of peaks in the reflection band and a plurality of wavelengths indicating the half value of the reflectance maximum value, a wavelength existing at the longest wavelength position is referred to as a cutoff wavelength. . At this time, those whose reflection band does not cover the ultraviolet region and / or the high energy visible light region are excluded. For example, in the case of having reflection bands in two wavelength bands of a wavelength band of 300 nm or more and 400 nm or less and a wavelength band of 500 nm or more and 600 nm or less, the former half of the maximum value of reflectance in the wavelength band of 300 nm or more and 400 nm The cutoff wavelength 示 す shown is to be selected from the wavelength band of 300 nm to 400 nm, and the wavelength showing the same reflectance is present in the wavelength band of 500 nm to 600 nm. The absence of a reflection band in the ultraviolet region makes it not a subject of the present invention. On the other hand, in the case of having a series of reflection bands at a wavelength of 350 nm or more and 450 nm or less, since it has a reflection band of 350 nm or more and 380 nm or less in the ultraviolet region and high energy visible light region, it becomes the target reflection band in the present invention. .

  Further, as described later, the reflected hue b * value indicates the reflected hue b * value when the laminated film is irradiated with daylight (D65 light source) containing ultraviolet light. A light beam in the wavelength range of 400 nm to 440 nm corresponds to the high energy visible light region and covers the violet to blue visible light region, so the reflected light becomes bluish and the reflected hue b which is an index of yellow and blue * Reflected in the value. The relational expression expressed by equation (2) as an equation shows the correlation between the cutoff wavelength and the b * value in the relative reflection spectrum when natural light is irradiated to the laminated film of the present invention. When the laminated film of the present invention is irradiated with linearly polarized light having an absolute light transmittance of less than 10% at a wavelength of 400 nm and the absolute reflection spectrum is measured, it is compared with the relative light reflection spectrum measured by irradiating natural light. It is characterized in that it exhibits sharp ray cuttability on the longer wavelength side. Therefore, since the cutoff wavelength に お け る in the absolute ray reflection spectrum indicates a numerical value larger than the cutoff wavelength in the relative ray reflection spectrum, the inequality of the equation (2) is satisfied. When the cutoff wavelength Λ and the reflected hue b * value do not satisfy the relational expression of equation (2), there is no change in the spectral spectrum between natural light irradiation and linear polarized light irradiation, and a wavelength of 400 nm or more and 440 nm In the case where the following high energy visible light region has a cutoff wavelength, the laminated film may have strong purple to blue reflection and yellow coloration.

  The laminated film of the present invention preferably contains a UV absorber. The layer containing the ultraviolet absorber may be either an A layer mainly composed of a thermoplastic resin A or a B layer mainly composed of a thermoplastic resin B, both layers of the A layer B layer It may be. The ultraviolet absorber described in the present invention refers to an additive having a maximum wavelength in the ultraviolet region of 300 nm or more and 380 nm or less in absorbance. The term "maximum wavelength" as used in the present invention refers to the peak wavelength having the maximum absorbance when having a plurality of maximum peaks. As in the laminated film of the present invention, in the method of alternately laminating the A layer and the B layer and cutting light by reflection, the thermoplastic resin A developed by the combination of two types of thermoplastic resins, stretching conditions and heat treatment conditions It is not easy to completely cut light over the reflection wavelength band, because the light reflectance changes appropriately depending on the refractive index difference of the thermoplastic resin B, the layer thickness distribution and the film thickness. Therefore, by combining the light absorption by the containing of the ultraviolet light absorber and the light reflection by the alternate lamination of the laminated films, it is possible to more effectively exhibit sufficient ultraviolet ray cutting properties. In addition, the combined use of light absorption and light reflection increases the optical path length of the absorbed ultraviolet light, and increases the absorption efficiency as compared with the case where the reflection band does not exist in the ultraviolet light region, and facilitates complete ultraviolet light cutting performance. It is possible to achieve Furthermore, since the content can be suppressed as compared with the case of light ray cutting only by absorption, there is a great advantage in suppressing the phenomenon of precipitation on the film surface (bleed out phenomenon).

  The ultraviolet absorber may be contained as an additive inside the resin, or may be copolymerized with the resin. Many UV absorbers have low molecular weight, and when they are not high molecular weight UV absorbers, they volatilize in the air when they are melted and discharged as a sheet, and problems such as precipitation on the film surface in heat treatment processes and reliability tests Will occur. Therefore, by copolymerizing with a resin, it is possible to securely hold the ultraviolet light absorber in the layer, and even when it is contained in the layer positioned on the outermost surface, it becomes possible to clear the problem of bleed out. In the case of copolymerization with a resin, for example, in the case of copolymerizing a polyester-based resin and an ultraviolet light absorber, the hydroxy group end contained in many of the ultraviolet light absorbers is transesterified or the like in the polyester resin. It can be achieved by reacting with a carboxyl group terminal.

  It is preferable that the ultraviolet absorber contains only the layer located in the inner layer of the laminated film or the layer located in the inner layer of the laminated film more than the layer located in the outer layer of the laminated film. In particular, when the laminated film of the present invention is a laminated film in which the A layer is alternately laminated such that the A layer is both surface layers and the B layer is an inner layer, the UV absorber is most preferably contained only in the B layer. When it is contained in the A layer including the outermost layer, in the crystalline layer, the volume of the amorphous region which is a region where the additive can be retained is small, and the above-mentioned bleed out phenomenon and the phenomenon of sublimation and volatilization near the nozzle occur. As a result, the film casting machine may be contaminated and precipitates may adversely affect the processing process. When the ultraviolet absorber is contained only in the inner layer B, the layer A mainly composed of the thermoplastic resin A located on the outermost layer plays a role as a lid to prevent the precipitation of the ultraviolet absorber, and thus bleed out phenomenon Is less likely to occur and is desirable.

  The content of the ultraviolet light absorber is preferably 2.5 wt% (wt%) or less, more preferably 1.5 wt% or less, still more preferably 1.0 wt% or less based on the total weight of the laminated film . When the content is more than 2.5 wt%, the light transmittance decreases and the white turbidity (haze value) of the film increases, which may cause a problem of deterioration in visibility when mounted on a display. The lower limit of the addition concentration is 0.01 wt%, depending on the total thickness of the film, in order to make the ultraviolet ray cut by the ultraviolet ray absorber sufficient.

  The UV absorbers used in the laminated film of the present invention include UV rays having various skeletal structures including benzotriazole, benzophenone, benzoate, triazine, benzoxazinone, salicylic acid and benzooxazine. Absorbents can be used. When two or more types of UV absorbers are used in combination, they may be UV absorbers having the same skeletal structure, or may be UV absorbers having different skeletal structures. Although specific examples will be exemplified below, (*) is attached after the compound name for the ones having the maximum wavelength in the wavelength band of 320 nm or more and 380 nm or less. The ultraviolet absorber used in the present invention is preferably an ultraviolet absorber having a maximum absorption wavelength in a wavelength range of 320 nm to 380 nm. When the maximum wavelength is shorter than 320 nm, it is difficult to sufficiently exhibit the absorption performance up to the ultraviolet region on the long wavelength side. Therefore, in order to set the maximum value of the light transmittance in the ultraviolet region of wavelengths 300 nm or more and 380 nm or less to 10% or less, it is particularly preferable to use the ultraviolet absorber to which (※) is attached.

  The benzotriazole-based ultraviolet absorber is not particularly limited. For example, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole (*), 2- (2'-hydroxy-3 ', 5'-) Di-tert-butylphenyl) benzotriazole (※), 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole (※), 2- (2′-hydroxy- 3'-tert-butyl-5'-methylphenyl) benzotriazole (*), 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole (*), 2- (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) -5-chlorobenzotriazole (*), 2- (2'-hydroxy-3'-(3 ", 4", 5 ") , 6 "- Trahydrophthalimidomethyl) -5'-methylphenyl) -benzotriazole (*), 2- (5-chloro-2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol (*), 2,2'-Methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol (*), 2- (2'-hydroxy-3 ') , 5'-di-tert-pentylphenyl) benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, 2,2'-methylenebis (4-tert-octyl-6-benzotriazole) B) phenol (*), 2- (5-butyloxy-2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol (*), 2- (5-) Siloxy-2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol (*), 2- (5-octyloxy-2H-benzotriazol-2-yl) -6-tert-butyl- 4-Methylphenol (*), 2- (5-dodecyloxy-2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol (*), 2- (5-octadecyloxy-2H- Benzotriazol-2-yl) -6-tert-butyl-4-methylphenol (*), 2- (5-cyclohexyloxy-2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol (*), 2- (5-propenoxy-2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol (*), 2- (5- (4-methyl) Phenyl) oxy-2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol (*), 2- (5-benzyloxy-2H-benzotriazol-2-yl) -6-third Butyl-4-methylphenol (*), 2- (5-hexyloxy-2H-benzotriazol-2-yl) -4,6-di-tert-butylphenol (*), 2- (5-octyloxy-2H-) Benzotriazol-2-yl) -4,6-di-tert-butylphenol (*), 2- (5-dodecyloxy-2H-benzotriazol-2-yl) -4,6-di-tert-butylphenol (*), 2- (5-sec-butyloxy-2H-benzotriazol-2-yl) -4,6-di-tert-butylphenol (*) and the like.

  The benzophenone-based ultraviolet absorber is not particularly limited, and examples thereof include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 2,2'-dihydroxy-4- Methoxy-benzophenone (*), 2,2'-dihydroxy-4,4'-dimethoxy-benzophenone, 2,2 ', 4,4'-tetrahydroxy-benzophenone, 5,5'-methylene bis (2-hydroxy-4) -Methoxy benzophenone), and the like.

  The benzoate-based UV absorber is not particularly limited. For example, resorcinol monobenzoate, 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, 2,4-di-tert-butyl ester Amylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, 2,6-di-tert-butylphenyl-3 ', 5'-di-tert-butyl-4'-hydroxybenzoate, hexadecyl-3,5- Di-tert-butyl-4-hydroxybenzoate, octadecyl-3,5-di-tert-butyl-4-hydroxybenzoate and the like can be mentioned.

  The triazine-based UV absorber is not particularly limited, but 2- (2-hydroxy-4-hexyloxyphenyl) -4,6-diphenyl-s-triazine, 2- (2-hydroxy-4-propoxy-5-) Methylphenyl) -4,6-bis (2,4-dimethylphenyl) -s-triazine, 2- (2-hydroxy-4-hexyloxyphenyl) -4,6-dibiphenyl-s-triazine, 2,4 -Diphenyl-6- (2-hydroxy-4-methoxyphenyl) -s-triazine, 2,4-diphenyl-6- (2-hydroxy-4-ethoxyphenyl) -s-triazine, 2,4-diphenyl-6 -(2-hydroxy-4-propoxyphenyl) -s-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyphenyl) -s Triazine, 2,4-bis (2-hydroxy-4-octoxyphenyl) -6- (2,4-dimethylphenyl) -s-triazine, 2,4,6-tris (2-hydroxy-4-hexyloxy) -3-Methylphenyl) -s-triazine (*), 2,4,6-tris (2-hydroxy-4-octoxyphenyl) -s-triazine (*), 2- (4-isooctyloxycarbonylethoxy) Phenyl) -4,6-diphenyl-s-triazine (*), 2- (4,6-diphenyl-s-triazin-2-yl) -5- (2- (2-ethylhexanoyloxy) ethoxy) phenol Etc.

  Examples of the benzoxazine-based ultraviolet light absorber include, but are not limited to Bis (6-methyl-4H-3,1-benzoxazin-4-one), 2,2'-p-phenylenebis (6-chloro-4H-3,1-benzoxazin-4-one) (*) 2,2'-p-phenylenebis (6-methoxy-4H-3,1-benzoxazin-4-one), 2,2'-p-phenylenebis (6-hydroxy-4H-3,1-benzo Oxazin-4-one), 2,2 '-(naphthalene-2,6-diyl) bis (4H-3,1-benzoxazin-4-one) (*), 2,2'-(naphthalene-1,5) 4-Diyl) bis (4H-3, 1-benzoxadi 4-one) (※), 2,2 '- (thiophene-2,5-diyl) bis (4H-3,1-benzoxazin-4-one) (※) and the like.

  As other ultraviolet light absorbers, for example, salicylic acid based compounds such as phenyl salicylate, t-butylphenyl salicylate, p-octylphenyl salicylate and the like, and others based on natural products (for example oryzanol, shea butter, baicalin Etc.), biological systems (eg, keratinocytes, melanin, urokanin etc.) and the like can also be used. In the case of an inorganic UV absorber, it is not compatible with the base resin and causes an increase in haze, which deteriorates the visibility when displaying an image, so it is not preferable to use it in the laminated film of the present invention.

The UV absorber used in the present invention has a solubility parameter of the UV absorber of δ _UVA [(cal / cm ³ ) ^1/2 ], and a solubility parameter of the thermoplastic resin containing the UV absorber of δ _polym [(cal / cm) ³ ) ^1/2 ], it is preferable that | δ _{UVA −} δ _polym | ≦ 2.0. Here, the "thermoplastic resin containing an ultraviolet absorber" refers to the thermoplastic resin having the highest content among the thermoplastic resins in the layer to which the ultraviolet absorber is added. The dispersion parameter of the ultraviolet absorber to the resin is improved by setting the solubility parameter of the ultraviolet absorber added to the resin and the resin constituting the layer to which the ultraviolet absorber is added to a close numerical value. Furthermore, the internal haze is increased by the formation of crystal nuclei between the ultraviolet absorbers, and the haze increase due to the bleed out of the ultraviolet absorber generated after the long-term durability test is reduced, and high transparency can be maintained. From the above viewpoint, | δ _UVA −δ _polym | is more preferably 1.5 or less, still more preferably 1.0 or less.

Although the solubility parameter can be estimated by the calculation method of Hansen, Hoy, and Fedors, etc., in the present invention, the calculation method of Fedors which can be calculated relatively easily based on the molecular structural formula is used. According to the Fedors calculation method, it is thought that solubility changes depending on the aggregation energy density and molar molecular volume of the molecule depending on the type and number of substituents, and the solubility parameter is estimated according to the equation (3). Here, E _coh (cal / mol) represents cohesive energy, and V represents molar molecular volume (cm ³ / mol).

  The solubility parameter of the thermoplastic resin can be estimated using the formula of Fedor based on the repeating structural unit of the molecular chain, and the solubility parameter of the thermoplastic resin containing the structural unit derived from the copolymerization component is each structural unit The ratio can be calculated according to the ratio of The solubility parameter in the present invention is a value obtained by rounding off the second decimal place of the estimated value calculated based on Fedor's equation. In addition, as a solubility parameter of a typical thermoplastic resin, cellulose acetate: 11.0, cellulose: 15.6, polyacrylonitrile: 14.8, polyamide: 13.6, polyisobutylene: 7.7, polyethylene: 8 .0, polyethylene terephthalate: 10.7, polyvinyl chloride: 10.1, polyvinyl acetate: 9.5, polystyrene: 9.4, polyvinyl alcohol: 12.6, polybutadiene: 8.3, polymethyl methacrylate: 9.3 and the like.

Examples of the combination of the ultraviolet light absorbers having good compatibility with the above-mentioned thermoplastic resin include the following examples. When the thermoplastic resin is cellulose acetate or polyethylene terephthalate, for example, 2- (2H-benzotriazol-2-yl) -4,6-di-tert-pentylphenol (δ _UVA : 11.9), 2 , 2′-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol (δ _UVA : 12.2), 2,4,6- Tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -s-triazine (δ _UVA : 11.6), 2,4-bis (2-hydroxy-4-butoxyphenyl) -6- (2, 4- bis butoxyphenyl) -s-triazine (δ _UVA:. 12.7), etc. can be suitably used also play a thermoplastic resin is polyacrylonitrile and polyamide The 2- (5-chloro -2H- benzotriazol-2-yl) -6-tert-butyl-4-methylphenol ([delta] _UVA: 13.2) and 2,2'-p-phenylene bis (4H (-3,1-benzoxazin-4-one) (δ _UVA : 14.1) etc. It is to be noted that the preferred combination of the thermoplastic resin and the UV absorber is not limited to the above, and the formula ( Any combination satisfying 3) is preferable.

  More preferably, the ultraviolet absorber used in the present invention has the same basic molecular structure as that of the above-described ultraviolet absorber, and has an oxygen atom replaced with a sulfur atom of the same group. Specific examples thereof include ones in which an ether group is converted to a thioether group, a hydroxyl group is converted to a mercapto group, and an alkoxy group is converted to a thio group. By using the ultraviolet absorber having a substituent containing a sulfur atom, it is possible to suppress the thermal decomposition of the ultraviolet absorber when it is heated and kneaded into the resin. In addition, the use of a sulfur atom and the selection of an appropriate alkyl chain make it possible to reduce the melting point by suppressing the intermolecular force between the ultraviolet absorbers, and therefore the compatibility with the thermoplastic resin It can be enhanced. By enhancing the compatibility with the resin, it is possible to maintain high transparency even when the ultraviolet absorber is added at a relatively high concentration. In particular, the use of a sulfur atom-containing benzotriazole-based and / or triazine-based ultraviolet absorber having high heat resistance and high absorption performance in addition to good compatibility with the polyester resin which is a preferable thermoplastic resin Is most preferred. Among them, it is preferable to satisfy the relational expression of the solubility parameter of the formula (3) from the viewpoint of maintaining high transparency for a longer period of time.

  The UV absorber used in the present invention preferably has a long functional alkyl chain. Since the intermolecular interaction is suppressed and the packing of the ring structure is less likely to occur due to the longer alkyl chain, when the film is heat-treated, it becomes difficult for the ultraviolet absorbers to form a crystal structure, which causes crystallization or bleeding. It leads to suppressing the whitening of the film by out. The length of the alkyl group contained in the functional group is preferably 4 or more and 18 or less, more preferably 4 or more and 10 or less, and still more preferably 6 or more and 8 or less. If the length of the alkyl chain is longer than 18, the reaction during the synthesis of the ultraviolet absorber is difficult to progress due to steric hindrance, which results in a decrease in the yield of the ultraviolet absorber, which is not realistic.

  As additives other than the ultraviolet light absorber which can be used for the laminated film of the present invention, for example, antioxidants, light stabilizers, heat resistant stabilizers, dyes, weathering stabilizers, organic lubricants, organic or inorganic fine particles Fillers, antistatic agents, nucleating agents, flame retardants, etc. may be added to the extent that they do not deteriorate the properties of the film that should be originally satisfied. In particular, ultraviolet absorbers are susceptible to two types of effects: thermal degradation influenced by oxygen in a resin extrusion process in a film forming process, and photodegradation by reaction with ultraviolet light and oxygen. Therefore, it is preferable to use an antioxidant for the former and a light stabilizer for the latter as an additive.

  The laminated film of the present invention cuts light rays from the ultraviolet region to the high energy visible light region, and has high light transmittance in the visible light region and exhibits high transparency, so that high energy visible light with a wavelength of 400 nm or less is particularly high. In fields requiring ray cutting up to the area, for example, window films in building materials and automotive applications, films for laminating steel plates on billboards etc., light-cut films for laser surface processing, and in electronic device applications Also in the fields of photolithography material process, mold release film, display optical film, other food, medicine, ink, etc., it is possible to use as a film application for the purpose of light deterioration suppression of contents.

  In particular, since the laminated film of the present invention exhibits the property of exhibiting long wavelength ultraviolet ray cutability for transmitted polarized light and low reflected color for light reflected on the surface, it is a display, especially a polarizer. It can be preferably used as a display having The display refers to a wide variety of displays such as flat panel displays, flexible displays, touch panels, and head-up / head-mounted displays in the augmented reality (AR) / virtual reality (VR) field. More specifically, devices such as large screen vision / monitor, digital signage, PC monitor, medical monitor, in-vehicle display, television, tablet, smartphone, wearable terminal, smart window, electronic paper, digital license plate and the like can be mentioned. In addition, when mounted on a display, it may be in the state of a laminated film, or as described later, it may be in the state of a laminated sheet in which a hard coat layer or an adhesive layer is laminated on the laminated film.

  As a film for display use using a polarizer, for example, in the case of a liquid crystal display, a polarizer protective film or a retardation film constituting a polarizing plate, various surface treated films located on the front of the display having antiglare or clear hard coat, back A brightness enhancement film, an antireflective film, a transparent conductive base film used for ITO, etc. located immediately before a light, an ultraviolet protective film of a touch sensor member, etc. may be mentioned. In the case of an organic EL display, for the purpose of protecting contents from outside light, a λ / 4 retardation film or a polarizer protective film constituting a circularly polarizing plate disposed on the viewing side (upper side) of the light emitting layer. The various optical films incorporated can be mentioned. In particular, the present laminated film can exhibit long wavelength ultraviolet cuttability with respect to polarized light vibrating in a specific direction, and natural light such as external light can be reflected without affecting long wavelengths to exhibit high transparency. It is preferable to arrange | position on the visual recognition side (upper side) rather than a polarizer as an optimal application place which can utilize a characteristic. In addition, when another optical film for display is present between the polarizer, when the optical film has birefringence, the characteristics of the polarizer obtained through the polarizer are deteriorated, and sufficiently There is a possibility that the characteristics of the laminated film of this development can not be utilized. Therefore, the laminated film of the present invention is a polarizer protective film, a retardation film, and a transparent conductive film which are disposed closer to the viewing side than the polarizer while being adjacent to the polarizer, or they are functionally integrated. Most preferably, it is used as an optical film. When adjacent to the polarizer, an adhesive may be interposed for the purpose of laminating the laminated film and the polarizer.

  When the laminated film of the present invention is used as a display application having a polarizer, the absolute light transmittance at a wavelength of 400 nm is less than 10%, less than 70% at a wavelength of 420 nm, and 80 at a wavelength of 440 nm. It is preferable that the optical axis of linearly polarized light showing% or more and the transmission axis of the polarizer in the display be arranged in parallel. The term "parallel" as used herein means the angle between the transmission axis of the polarizer in the display and the optical axis of linearly polarized light showing less than 10% at 400 nm, less than 70% at 420 nm, and 80% or more at 440 nm. Represents 0 ° or more and 10 ° or less, preferably 0 ° or more and 5 ° or less. As described above, when the direction in which long-wavelength ultraviolet ray cutting properties can be exhibited and the transmission axis of the polarizer are not arranged substantially in parallel, the polarization of the display may be impaired, or problems such as rainbow unevenness may occur. Since the long wavelength ultraviolet ray cut-off property is not sufficiently indicated, the protection of the contents of the display is not sufficiently achieved and the image display is deteriorated. Of course, if, among the X and Y waves, the optical axis of linearly polarized light having an absolute light transmittance of 10% or more at a wavelength of 400 nm and the transmission axis of a polarizer in the display are arranged substantially parallel to each other Although the high transparency can be maintained when natural light of external light is reflected, the long wavelength ultraviolet ray cut property in transmitting polarized light is weakened, so that deterioration of the contents of the display may occur.

  Furthermore, the laminated film of the present invention can be preferably applied as a head-up display application having a polarizer. A head-up display is a display that displays information superimposed on a normal field of view by projecting light emitted from a display unit onto a projection member and projecting a virtual image at an infinite distance point. It is used as a display device for medical applications and also for head mounted display applications such as VR and AR. Since a normal display has a configuration in which the display unit is adjacent to the vicinity of the projection unit, light emitted by the display unit is mainly viewed from the front direction. On the other hand, the head-up display is a mode for visually recognizing a virtual image formed by the light emitted from the display unit being irradiated to the projection unit directly or through a reflecting mirror (cold mirror) or the like. That is, in the head-up display, the projection unit and the display unit are not adjacent to each other, and usually the viewer does not directly view the light from the display unit from the front (FIGS. 4 and 5). In addition, about the material which comprises a projection part, if the display of a virtual image can be performed, it will not be specifically limited, For example, glass, resin, etc. can be used.

  As described above, in the head-up display, the viewer visually recognizes the virtual image formed on the projection unit. Therefore, even if the laminated film of the present invention is used, the rainbow color observed through polarized sunglasses caused by the decrease in transparency due to the reflection band reaching the visible light region and the optical anisotropy caused by biaxial stretching There is no problem regarding visibility such as a pattern, and a clear display can be obtained for the viewer. On the other hand, the light ray cut effect inherent to the laminated film of the present invention can be obtained for a polarizer, a display panel, and a self-emission panel part constituting a display. In addition, in the head-up display, since the viewer does not directly view the display of the polarization state, it is possible to emit an iridescent pattern even when the display unit (projection member) is viewed through the polarization sunglasses. Instead, it becomes possible to visually recognize the image.

  In particular, in the case of a head-up display for vehicles, the display unit such as the display panel unit and the self-emission panel unit may be mounted inside the vehicle as shown in FIG. For example, a configuration in which light from the light emitting device is applied to the combined display unit and displayed may be used. The head-up display in FIGS. 4 and 5 will be briefly described below. In the head-up display of FIG. 4, the light emitted from the display unit 11 located inside the interior panel unit 10 is reflected by the reflecting mirror 12 and reaches the projection member 13 to form a virtual image 14 to be visually recognized. (The light path at this time is shown by 15). At this time, the viewer visually recognizes the virtual image 14 visually recognized on the projection member 13. Further, in the head-up display of FIG. 5, the virtual image 14 to be visually recognized is formed when the light from the light projecting device 16 reaches the display unit 11 built in or bonded to the projection member 13. At this time, the viewer visually recognizes the virtual image 14 visually recognized on the complex of the display unit 11 and the projection member 13.

  The arrangement of the laminated film of the present invention in the head-up display is not particularly limited as long as the effects of the present invention are not impaired. For example, in the configuration of FIG. It is preferable to arrange | position to the front surface (outer surface) of the display part 11 at the point which reduces deterioration of a structural component. Furthermore, when the laminated film of the present invention is arranged in this way, even if the laminated film exhibits optical anisotropy, the viewer does not directly view the display of the polarization state, so it is possible to use polarized sunglasses etc. It is also preferable that the rainbow pattern does not easily occur in the virtual image 14 that is also visually recognized. Further, in the configuration of FIG. 5, it is assumed that the display unit 11 is directly installed on a window glass or the like, and both surfaces of the display unit 11 may be exposed to external light. In order to reduce, light absorption may be performed by the component of the polarizing plate. In consideration of this point, in order to reduce deterioration of the polarizing plate, it is preferable to place the laminated film of the present invention on the front surface of the polarizing plate.

  Next, the preferable manufacturing method of the laminated | multilayer film of this invention is demonstrated below. Of course, the present invention is not construed as being limited to such examples.

  Thermoplastic resin A and thermoplastic resin B are prepared in the form of pellets or the like. The pellets are optionally dried in hot air or under reduced pressure and then fed to separate extruders. In the extruder, each resin heated and melted at a temperature equal to or higher than the melting point is equalized in extrusion amount by a gear pump or the like, and foreign substances, denatured resin and the like are removed through a filter or the like. These resins are formed into a desired shape by a die and then discharged into a sheet. Then, the sheet discharged from the die is extruded onto a cooling body such as a casting drum and cooled and solidified to obtain a casting film. Under the present circumstances, it is preferable to closely_contact | adhere to cooling bodies, such as a casting drum etc., by electrostatic force using a wire-like, tape-like, needle-like or knife-like electrode, and to make it harden rapidly. It is also preferable to blow air from a slit-like, spot-like or plane-like device to adhere closely to a cooling body such as a casting drum to cause rapid solidification, or to closely adhere to a cooling body with a nip roll to cause rapid solidification.

  In addition, a plurality of resins of the thermoplastic resin A and the thermoplastic resin B are sent out from different flow paths using two or more extruders, and sent to the multilayer laminating apparatus before being discharged in the form of a sheet. Although a multi-manifold die, a feed block, a static mixer, etc. can be used as a multi-layer laminating apparatus, in particular, in order to efficiently obtain the layer configuration of the laminated film of the present invention, a feed block having fine slits is used Is preferred. When such a feed block is used, the apparatus does not become extremely large, so that the amount of foreign matter generation due to thermal degradation is small, and high-precision lamination can be performed even when the number of laminations is extremely large. In addition, the lamination accuracy in the width direction is also significantly improved as compared with the prior art. Further, in this device, since the thickness of each layer can be adjusted by the shape (length, width) of the slit, it is possible to achieve an arbitrary layer thickness.

  The molten multilayer laminate thus formed in the desired layer configuration is directed to a die to obtain a casting film as described above. The obtained casting film is preferably subsequently biaxially stretched in the longitudinal direction and the width direction. The stretching may be sequentially biaxially stretched or may be simultaneously biaxially stretched. In addition, re-stretching may be performed in the longitudinal direction and / or the width direction.

  First, the case of sequential biaxial stretching will be described. Here, stretching in the longitudinal direction refers to uniaxial stretching for giving molecular orientation in the longitudinal direction to the film, which is usually performed according to the peripheral speed difference of the roll, and may be performed in one step, and plural It may be done in multiple stages using book roll pairs. The magnification of stretching varies depending on the type of resin, but is preferably 2 to 15 times, and when polyethylene terephthalate is used for any of the resins constituting the laminated film, 2 to 7 times is particularly preferably used. Moreover, it is preferable to set as extending | stretching temperature in the range of the glass transition temperature of resin which comprises laminated | multilayer film-glass transition temperature +100 degreeC.

  The uniaxially stretched film thus obtained is subjected to surface treatment such as corona treatment, flame treatment, plasma treatment and the like as necessary, and then functions such as slipperiness, adhesion, antistaticity, etc. It may be applied by in-line coating.

  Stretching in the width direction refers to stretching for giving the film orientation in the width direction. Stretching in the width direction is usually carried out by using a tenter, conveying while gripping both ends in the width direction of the film with clips to gradually increase the distance between the opposing clips. The stretching ratio of stretching varies depending on the type of resin, but usually 2 to 15 times is preferable, and 2 to 7 times is particularly preferably used when polyethylene terephthalate is used for any of the resins constituting the laminated film. Moreover, as extending | stretching temperature, the glass transition temperature of the resin which comprises a laminated film-glass transition temperature +120 degreeC is preferable.

  The thus biaxially stretched film is heat-treated in the tenter to a temperature not lower than the stretching temperature and not higher than the melting point, uniformly and slowly cooled, then cooled to room temperature and taken up. In addition, in order to provide a low orientation angle and thermal dimensional stability of the film, relaxation treatment or the like in the longitudinal direction and / or the width direction may be used in combination at the time of heat treatment to slow cooling.

  In particular, in order to develop the reflection anisotropy characteristic of the laminated film of the present invention, as described above, it is preferable that the draw ratio in the longitudinal direction and the width direction be different. At this time, it is also possible to perform stretching for the second time in the longitudinal direction or the width direction after performing stretching in the longitudinal direction and the width direction once each. This can give the laminated film a stronger orientation in a specific direction. When the second stretching in the longitudinal direction or width direction is performed, the total stretch ratio in the longitudinal direction and the width direction may be 2 to 7 times, and the magnification may be different in the longitudinal direction and the width direction. . In particular, the difference between the draw ratios in the longitudinal direction and the width direction is preferably 0.5 times to 3.0 times as an absolute value, and more preferably 1.0 times to 2.0 times. . If the magnification is different by more than 3.0 times, the laminated film may be easily torn in the strongly stretched direction, which may not be preferable. When the difference between the draw ratio in the longitudinal direction and the width direction is smaller than 0.5, the reflection anisotropy is not sufficiently expressed when irradiated with linearly polarized light in each of the alignment direction and the direction perpendicular thereto. There is.

  Subsequently, the case of simultaneous biaxial stretching will be described. In the case of simultaneous biaxial stretching, the obtained cast film is subjected to surface treatment such as corona treatment, flame treatment, plasma treatment and the like as necessary, and then, it has slipperiness, easy adhesion, antistatic property, etc. The function may be imparted by in-line coating.

  Next, the cast film is guided to a simultaneous biaxial tenter, conveyed while holding both ends of the film with clips, and simultaneously and / or stepwise drawn in the longitudinal direction and the width direction. The simultaneous biaxial stretching machine includes a pantograph system, a screw system, a drive motor system, and a linear motor system. However, a drive motor system or a drive motor system which can change the draw ratio arbitrarily and can perform relaxation processing at any place The linear motor system is preferred. Although the magnification of stretching varies depending on the type of resin, in general, the area magnification is preferably 6 to 50 times, and when polyethylene terephthalate is used for any of the resins constituting the laminated film, the area magnification is 8 to 30 times It is particularly preferably used. Moreover, in order to strongly express the orientation in a specific direction in the plane, it is also preferable to make the draw ratios in the longitudinal direction and the width direction different numerical values. The stretching speed may be the same speed, or may be stretched in the longitudinal direction and the width direction at different speeds. Moreover, as extending | stretching temperature, the glass transition temperature of the resin which comprises a laminated film-glass transition temperature +120 degreeC is preferable.

  In this way, in order to impart planarity and dimensional stability, it is preferable that the film subjected to the simultaneous biaxial stretching be subsequently subjected to a heat treatment in the tenter and not lower than the stretching temperature and not higher than the melting point. During the heat treatment, in order to suppress the distribution of the main orientation axis in the width direction, it is preferable to carry out relaxation treatment instantaneously immediately before and / or immediately after entering the heat treatment zone. The biaxially stretched film is heat-treated in this manner, uniformly annealed, cooled to room temperature and taken up. Further, if necessary, relaxation treatment may be performed in the longitudinal direction and / or the width direction at the time of heat treatment to slow cooling. A relaxation treatment is instantaneously performed immediately before and / or immediately after entering the heat treatment zone.

  The laminated film obtained as described above is trimmed to a required width via a winding device, and wound in a roll state so as not to be wound up. At the time of winding, both ends in the film width direction may be embossed to improve the winding shape.

  In the laminated film of the present invention, it is preferable that the direction in which the oriented film is more strongly oriented is the width direction. In the case of strongly stretching in the longitudinal direction, since stretching is performed by tension utilizing the circumferential speed difference between the rolls as described above, the film and the roll are rubbed at the time of stretching and the film is scratched in the width direction. A shrinking necking phenomenon may occur to easily cause thickness unevenness of the film. In stretching in the width direction, since the clip is held by the clip in the width direction and stretched, there is no problem that a scratch is generated, and it is preferable because the possibility of causing a strong neckdown is low.

  When the laminated film of the present invention is stretched, the stretching speed at the time of stretching is preferably 0.8 m / min or more and 10 m / min or less. By setting the stretching speed to the above range, appropriate heat supply can be performed to the laminated film, and uniform orientation stretching and anisotropy in the width direction can be achieved. When the drawing speed is 0.8 m / min or less, the birefringence of the resin constituting the laminated film can not be sufficiently expressed, and the anisotropy is different at any position in the width direction, which may lead to a decrease in productivity. . On the other hand, when it is larger than 10 m / min, the laminated film is rapidly stretched without sufficient supply of heat, and stretching unevenness may occur at the position in the film width direction, which may cause breakage of the film. A more preferable stretching speed is 3 m / min or more and 5 m / min or less, which can appropriately supply heat and perform uniform stretching in the width direction.

  The thickness of the laminated film of the present invention is not particularly limited, but is preferably 1 to 200 μm. According to the recent tendency toward thinning of an optical film for display use, the thickness is preferably 40 μm or less, more preferably 25 μm or less. Although there is no lower limit, it is necessary to have a certain thickness in order to provide sufficient ray-cut ability in ultraviolet light and high energy visible light region while using ultraviolet absorber addition and reflection anisotropy in combination, and also a roll In order to make the winding property stable and to form a film without breaking the film, it is practically preferable to have a thickness of 10 μm or more. If the thickness is less than 10 μm, the intended optical performance can not be imparted, and in addition, when the hard coat layer described later is provided, the laminated sheet may curl after the curing treatment.

  Next, a laminate sheet in which a hard coat layer mainly composed of a curable resin C is provided on the laminate film of the present invention will be described.

  The laminated film of the present invention has a hard coat layer (C layer) composed mainly of a curable resin C in order to add functions such as scratch resistance, dimensional stability, adhesion and adhesiveness to the upper part of the outermost layer. It can also be mentioned as a preferred embodiment that it is a laminated sheet provided on at least one side. In the case of a film for display use, a transport process is required to bond the rolled film with other display members, but when the film and the transport roll rub against each other, the film is mounted on the display There is a problem that visibility may deteriorate due to a scratch that occurs. In display applications, long-term heat resistance test under high temperature conditions at around 100 ° C, long-term heat and humidity resistance test under high humidity conditions of 90% RH to 95% RH at around 60 ° C, and from around 100 ° C to below freezing point It is required that the properties of the film do not change in long-term reliability tests under severe conditions, such as heat shock tests in which the temperature is raised and lowered over several degrees. In the case of the laminated film of the present invention which exhibits orientation and crystallization by stretching and exhibits birefringence, when subjected to a long-term reliability test, the dimensions of the film may change due to heat shrinkage. When the thickness of the film is increased due to such heat contraction, the reflection band may be shifted to cause problems such as coloring due to reflection of visible light on the longer wavelength side. Therefore, it is preferable to apply a hard coat layer contributing to dimensional stability to at least one surface of the laminated film in order to maintain film properties, particularly film dimensions. In addition, by laminating a hard coat layer having high crosslinkability, it is possible to further suppress the precipitation of oligomers, additives and the like contained in the inside of the laminated film. The hard coat layer may be coated directly on the laminated film, and coated with an in-line coating layer capable of imparting functions such as slipperiness and adhesion as described in the above-mentioned manufacturing method. It is also good.

  The in-line coating layer can not only impart functions such as easy sliding and easy adhesion, but also has the effect of improving the adhesion to the laminated film when laminating the hard coat layer containing the curable resin C as a main component. It is preferable to apply it for playing. The in-line coating layer is optionally subjected to a corona treatment on the laminated film as described in the preferred production method described later, and then a uniform film is formed using a wire meta bar, and a solvent such as water in the heat treatment step It can be formed by drying the components. The refractive index of the in-line coating layer is preferably a numerical value between the refractive index of the thermoplastic resin A constituting the laminated film and the refractive index of the curable resin C constituting the hard coat layer, and more preferably It is to show the middle value of the refractive index of both resins. For example, when using polyethylene terephthalate as the thermoplastic resin A and an acrylic resin as the curable resin C as in the examples described later, the former has a refractive index of about 1.65 after stretching, and the latter has a refractive index of 1.50. As the difference between the degree and the refractive index is increased, the adhesion may be deteriorated. Therefore, the refractive index of the coating layer preferably has a value of 1.50 or more and 1.60 or less, and more preferably 1.55 or more and 1.58 or less.

  The hard coat layer containing the curable resin C as a main component can be mentioned as a preferred embodiment in which it is preferably applied to only one side in view of the adhesion of the laminated film of the present invention to other display components via an adhesive. Although it can be done, when it is applied to one side, if the balance between the cure shrinkage of the hard coat layer and the heat shrinkage of the laminated film is not maintained, the curling problem of the member to which the laminated sheet is applied may occur. Therefore, in applications where the occurrence of curling is a problem, the hard coat layer is preferably applied to both sides of the laminated film as a preferred embodiment.

  The curable resin C used for the laminated sheet of the present invention is preferably highly transparent and durable. For example, acrylic resin, urethane resin, fluoro resin, silicone resin, polycarbonate resin, vinyl chloride resin alone or It can be mixed and used. In terms of curability, flexibility, and productivity, the curable resin C is preferably made of an active energy ray curable resin such as an acrylic resin represented by a polyacrylate resin. Moreover, when adding the abrasion resistance at the time of bending | flexion calculated | required when applying as a film for flexible displays, it is preferable that curable resin C consists of a thermosetting urethane resin.

  Hereinafter, the active energy ray curable resin used as a component of the hard coat layer will be described. Examples of monomer components constituting the active energy ray-curable resin include pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, and dipentaerythritol tetra (meth) acrylate. 2, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, bis (methacroylthiophenyl) sulfide, 2,4-dibromophenyl (meth) acrylate, 2, 3,5-Tribromophenyl (meth) acrylate, 2,2-bis (4- (meth) acryloyloxyphenyl) propane, 2,2-bis (4- (meth) acryloyloxyethoxy) Phenyl) propane, 2,2-bis (4- (meth) acryloyloxydiethoxyphenyl) propane, 2,2-bis (4- (meth) acryloylpentaethoxyphenyl) propane, 2,2-bis (4- (4- (meth) acryloyl) Meta) acryloyloxyethoxy-3,5-dibromophenyl) propane, 2,2-bis (4- (meth) acryloyloxydiethoxy-3,5-dibromophenyl) propane, 2,2-bis (4- (meth) ) Acryloyloxypentaethoxy-3,5-dibromophenyl) propane, 2,2-bis (4- (meth) acryloyloxyethoxy-3,5-dimethylphenyl) propane, 2,2-bis (4- (meth)) Acryloyloxyethoxy-3-phenylphenyl) propane, bis (4- (meth) acryloyloxyphenyl) Ruphon, bis (4- (meth) acryloyloxyethoxyphenyl) sulfone, bis (4- (meth) acryloyloxypentaethoxyphenyl) sulfone, bis (4- (meth) acryloyloxyethoxy-3-phenylphenyl) sulfone, bis (4- (meth) acryloyloxyethoxy-3,5-dimethylphenyl) sulfone, bis (4- (meth) acryloyloxyphenyl) sulfide, bis (4- (meth) acryloyloxyethoxyphenyl) sulfide, bis (4- (meth) acryloyloxyethoxyphenyl) sulfide (Meth) acryloyloxypentaethoxyphenyl) sulfide, bis (4- (meth) acryloyloxyethoxy-3-phenylphenyl) sulfide, bis (4- (meth) acryloyloxyethoxy-3,5-dimethylphenyl) sulfide, di Polyfunctional (meth) acrylic compounds such as (meth) acryloyloxyethoxy) phosphate and tri ((meth) acryloyloxyethoxy) phosphate can be used, and one or more of these can be used. .

  In addition to these polyfunctional (meth) acrylic compounds, styrene, chlorostyrene, dichlorostyrene, bromostyrene, dibromostyrene and divinyl are used to control the hardness, transparency, strength, refractive index, etc. of the active energy ray-curable resin. Benzene, vinyl toluene, 1-vinyl naphthalene, 2-vinyl naphthalene, N-vinyl pyrrolidone, phenyl (meth) acrylate, benzyl (meth) acrylate, biphenyl (meth) acrylate, diallyl phthalate, dimethallyl phthalate, diallyl biphenylate, or A reaction product of a metal such as barium, lead, antimony, titanium, tin or zinc with (meth) acrylic acid can be used. One or more of these may be used.

  As a method of curing the active energy ray curable resin, for example, a method of irradiating ultraviolet rays can be used. In this case, about 0.01 to 10 parts by weight of a photopolymerization initiator is added to the compound. It is desirable to add.

  The active energy ray-curable resin used in the present invention has isopropyl alcohol, ethyl acetate, methyl ethyl ketone, and the like insofar as the effects of the present invention are not impaired for the purpose of improving the workability at the time of coating and controlling the coating film thickness. Organic solvents such as toluene and propylene glycol monomethyl ether can be blended.

  The active energy ray in the present invention means an electromagnetic wave for polymerizing an acrylic vinyl group such as ultraviolet ray, electron beam, radiation (α ray, β ray, γ ray, etc.), and ultraviolet ray is practically simple. preferable. As an ultraviolet light source, an ultraviolet fluorescent lamp, a low pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a xenon lamp, a carbon arc lamp and the like can be used. In the case of curing with an ultraviolet light source, the oxygen concentration is preferably as low as possible in view of preventing oxygen inhibition, and curing in a nitrogen atmosphere is more preferred. In the case of the electron beam type, the apparatus is expensive and operation under an inert gas is required, but it is advantageous from the viewpoint that it is not necessary to contain a photopolymerization initiator, a photosensitizer and the like.

  The thickness of the hard coat layer should be properly adjusted depending on the method of use, but it is usually 1.0 to 6.0 μm in view of compatibility of thin film tendency for display application and hard coat performance. Preferably, it is more preferably 1.0 to 3.0 μm, and still more preferably 1.0 to 1.5 μm. When the thickness of the hard coat layer is greater than 6.0 μm, the laminated film may lose the curing shrinkage force of the hard coat layer when curing the coated substrate, and curl of the laminated sheet may occur strongly. When it apply | coats on both surfaces of laminated | multilayer film, it is preferable that the thickness of each hard-coat layer has the same thickness. When the thickness is different between the hard coat on the upper surface and the hard coat on the lower surface, the balance of shrinkage stress at the time of curing of each hard coat layer is lost, and curl may occur in the entire laminated sheet.

  As a thermosetting urethane resin used as a component of a hard coat layer containing a curable resin C as a main component for adding scratch resistance, a polycaprolactone segment and a polysiloxane segment and / or a polydimethylsiloxane segment are used. The resin which bridge | crosslinked the copolymer resin which it has with the compound which has an isocyanate group by heat reaction is preferable. By applying a thermosetting urethane resin, it is possible to make the hard coat layer tough and at the same time promote elastic recovery, and it is possible to add scratch resistance to the laminated film.

  As a curable resin C used to add adhesion and adhesiveness, when used as an optical film for a display, particularly as a laminate with a polarizer, it exhibits a good effect in close contact with PVA, It is preferable to use a photocurable resin composed of four combinations of a compound having an alicyclic epoxy group, a polyacrylate of a polyol, an oxetane compound, and a polymer having an alkyl acrylate as a monomer unit.

  The above-mentioned various ultraviolet absorbers and / or dyes may be added to the hard coat layer in the present invention. By separately adding to the inside of the laminated film and the hard coat layer, it is possible to reduce the added concentration of the ultraviolet light absorber and the dye added to the resin, and to suppress the bleed out phenomenon generated at the time of resin extrusion. preferable. Further, when a dye is added to the hard coat layer, even if bluish coloring is observed in the laminated sheet itself due to the reflected light to the viewing side, it becomes possible to reduce by absorption of the dye, and image display It is preferable from the point that clear color display becomes possible at the time of turning on and off.

  The concentration of the ultraviolet light absorber and / or dye added to the hard coat layer is preferably 10 wt% or less, more preferably 5 wt% or less, based on the entire resin composition constituting the hard coat layer. The addition concentration should be appropriately adjusted so as to achieve the target cutting performance in view of the absorption performance of the additive and the thickness of the hard coat layer involved in the cutting performance, but in the case of exceeding 10 wt%, In addition to whitening due to surface precipitation of various additives during curing of hard coat and after accelerated reliability test, ultraviolet absorber and / or pigment is precipitated at the interface of laminated film and hard coat layer, and laminated film and hard coat The adhesion of the layer may be degraded.

  In particular, as a dye that can be added to the hard coat layer (C layer) of the laminated sheet of the present invention, it is preferable to use a dye having a maximum wavelength which is maximum at a wavelength of 380 nm or more and 410 nm or less or a wavelength of 470 nm or more and 500 nm or less. When a light beam with a wavelength of 380 nm or more and 440 nm or less, which is high-energy visible light, is reflected, visible light of purple to blue may be visually recognized as the reflected light. In order to reduce the hue of the reflected light and make it closer to a transparent color, there is a method of adding an absorber exhibiting a yellow hue to obtain a neutral hue. At this time, a dye having a maximum wavelength in the wavelength band of 380 nm or more and 410 nm or less may be added for the purpose of absorbing the reflected light as it is and reducing the reflectance. A dye having a maximum wavelength at 470 nm or more and 500 nm or less may be added.

  In the present invention, as the dye, a dye which is excellent in chroma and capable of sharp cutting a narrow band wavelength may be added, or a pigment which is more excellent in heat resistance and light resistance than the dye may be used. The pigments can be roughly classified into organic pigments, inorganic pigments and classical pigments, but it is preferable to use organic pigments in view of compatibility with the thermoplastic resin to be added. The structure of the dye is not particularly limited, but is β-naphthol type, naphthol AS type, acetoacetic acid arylamide type, acetoacetic acid arylamide type, pyrazolone type, β oxynaphthoic acid type, β oxynaphthoic acid anilide type, acetoacetic acid anilide Such as azo, copper phthalocyanine, halogenated copper phthalocyanine, metal free phthalocyanine, phthalocyanine such as copper phthalocyanine lake, and others, acylamino yellow, azomethine, aniline, alizarin, anthraquinone, anthrapyrimidine, iso Indolinone, isoindoline, indigoid, indanthrone, indole, xanthene, quinacridone, quinophthalone, dioxazine, dichloroisobiolanthrone, dibromoanthrone, thulene , Thioindigo, triazine-based, triphenylmethane-based, naphthalimide, nitrone based, pyranthrone-based, pyrazolone, Furuorubin system, flavanthrone pigments, perinone pigments, perylene-based, benzotriazole-based, natural organic pigments. In particular, it is preferable to use a dye and a pigment having a maximum wavelength in the wavelength band of 380 nm or more and 410 nm or less, because the reflected light can be absorbed and coloring can be suppressed by reducing the reflectance. As such dyes, azo dyes, anthraquinone dyes, dioxazine dyes, triazine dyes, naphthalimide dyes, phthalocyanine dyes, benzylidine dyes and benzotriazole dyes can be preferably used. Moreover, it is preferable to use a dye and / or a pigment having a maximum wavelength in a wavelength band of 470 nm or more and 500 nm or less since coloration of purple to blue can be reduced by color tone correction, but as such a dye Azo type, anthraquinone type, isoindoline type, quinophthalone type, phthalocyanine type and the like.

  An adhesive layer containing a UV absorber and / or a dye may be laminated on the laminated film or laminated sheet of the present invention. The pressure-sensitive adhesive layer may be disposed on the viewing side (upper side) or the backlight side (lower side) of the laminated film or laminated sheet of the present invention in the case of a film for display. , May be arranged on both sides. When a pigment is added to the adhesive layer, the thickness is larger than that in the case where the pigment is contained in the hard coat layer, which contributes to the reduction of the additive amount.

  When achieving the target long-wavelength UV cuttability of the present invention through the reflection and / or absorption of the laminated film and the absorption of the adhesive layer, using a dye having a narrower band cuttability as the dye provides energy of Dyes themselves are susceptible to photodegradation by receiving strong ultraviolet light. Therefore, the ultraviolet ray cuttability by combined use of light reflection and light absorption of the laminated film of the present invention is utilized, and the adhesive layer contains an ultraviolet absorber and / or a dye, and the laminated film is located closer to the viewing side than the adhesive By making it into a structure, since deterioration of the pigment | dye contained in an adhesive can be fully prevented by a laminated film, long wavelength ultraviolet ray cut off property is maintained over a long period, and it becomes a more preferable aspect.

  The pressure-sensitive adhesive layer may be directly coated on a laminated film substrate and then dried to form a pressure-sensitive adhesive layer, and a pressure-sensitive adhesive sheet may be further obtained by laminating a release sheet. It may be a method of transferring onto a film substrate. The coating method can use various coating methods, such as a roll coater, a die coater, a bar coater, a lip coater, a gravure coater, and a blade coater. The thickness of the adhesive layer is preferably 5 μm or more and 150 μm or less, and more preferably 10 μm or more and 80 μm or less. When the thickness of the adhesive layer is less than 5 μm, the adhesiveness may be insufficient, and when it exceeds 150 μm, the cost of the adhesive sheet itself increases, which is not desirable. The type of pressure-sensitive adhesive is not particularly limited, but those described as a curable resin used to add the aforementioned adhesion and adhesion improvement, an acrylic optical pressure-sensitive adhesive (OCA), and It is most preferable to use a liquid acrylic optical adhesive (LOCA) because of its excellent transparency and durability.

  Hereinafter, the display of the present invention will be described. The display of the present invention comprises the laminated film of the present invention. Here, "comprised of the laminated film of the present invention" means that the laminated film or the laminated sheet of the present invention is included as a member constituting a display. Since the laminated film or the laminated sheet of the present invention exhibits a long wavelength ultraviolet ray cutting property for transmitted polarized light and a low reflection color for light reflected on the surface, such an embodiment By doing this, the visibility of the image processing apparatus can be improved, and the deterioration of the polarizer due to the long wavelength ultraviolet light can be reduced.

  Hereinafter, the present invention will be described according to examples, but the present invention is not limited to these examples. Each characteristic was measured by the following method.

(Method of measuring characteristics and method of evaluating effects)
The measuring method of the characteristic in this invention and the evaluation method of an effect are as follows.

(1) Layer Thickness, Number of Layers, Layer Structure The layer configuration of the film was determined by transmission electron microscopy (TEM) observation of a sample whose cross section was cut out using a microtome. That is, using a transmission electron microscope H-7100 FA type (manufactured by Hitachi, Ltd.), the cross section of the film was observed under the condition of an acceleration voltage of 75 kV, a cross section photograph was taken, and the layer configuration and each layer thickness were measured. In some cases, in order to obtain high contrast, a staining technique using RuO ₄ or OsO ₄ was used. In addition, according to the thickness of the thinnest layer (thin film layer) of all the layers captured in one image, if the thin film layer thickness is less than 50 nm, 100,000 times, the thin film layer thickness is 50 nm to 500 nm In the case of less than 40, 000, and in the case of 500 nm or more, the observation was carried out with a magnification of 10,000 and the layer thickness, the number of layers, and the layer structure were specified.

(2) Orientation Angle The automatic birefringence device KOBRA-21 ADH manufactured by Oji Scientific Instruments Co., Ltd. was used. A sample is cut out from a total of three locations of the laminated film width direction center and the middle between the width direction center and both width direction ends into 4 cm in the longitudinal direction x 5 cm in the width direction, each at 590 nm wavelength in the standard retardation measurement mode The refractive index maximum orientation in the film plane of was measured, and it was set as the orientation direction. In the film strongly stretched in the longitudinal direction or the width direction, the strongly stretched (higher magnification) direction was 0 °, and the angle formed by the strongly oriented axial direction was defined as the orientation angle. Of the orientation angles indicated by the three samples, the sample showing the largest numerical value was taken as the orientation angle of the present laminated film.

(3) Relative light transmittance in the case of natural light irradiation A Hitachi spectrophotometer U-4100 was used. An integrating sphere was attached, and the maximum value of the light transmittance in the wavelength region of 300 nm or more and 380 nm or less when the reflection of the aluminum oxide standard white plate (supplied with the main body) was 100% was read. As the measurement conditions, the scan speed was set to 600 nm / min, the sampling pitch was set to 1 nm, and measurement was continuously performed in the high resolution measurement mode.

(4) Absolute light transmittance at the time of irradiating linearly polarized light A spectrophotometer U-4100 manufactured by Hitachi, Ltd. was used. Using a normal incidence detector using a mirror surface, convert natural light from the light source into linearly polarized light of a specific direction via the attached polarization attachment, and continuously measure the wavelength range of 300 nm to 800 nm The absolute light transmittances at 400 nm, 420 nm and 440 nm at time were read. As the measurement conditions, the scan speed was set to 600 nm / min, the sampling pitch was set to 1 nm, and measurement was continuously performed in the high resolution measurement mode.

(5) Reflection spectrum and light reflectivity The Hitachi U-4100 spectrophotometer was used. An integrating sphere was attached, and relative light reflectance in a wavelength region of 300 nm or more and 800 nm or less was measured when reflection of an aluminum oxide standard white plate (supplied with the main body) was 100%, and a reflection spectrum in that range was obtained. As conditions, the scanning speed was set to 600 nm / min, the sampling pitch was set to 1 nm, and measurement was continuously performed.

(6) Reflection Hue b * Value The reflection hue b * of the laminated film was measured using a spectrocolorimeter CM3600 d manufactured by Konica Minolta Sensing. The b * value in the SCI mode was read at a viewing angle of 10 ° with an MVD attachment measuring 8 mm in diameter, and the light source was a D65 light source. Five points were randomly measured within a 10 cm square sample surface, and the average value was taken as the measured value.

(7) Formation of Hard Coat Layer (Examples 19 to 22)
Active energy ray-curable urethane acrylic resin (Nippon Synthetic Chemical Industry Co., Ltd. purple light UV) which comprises the hard-coat layer which added the ultraviolet absorber and / or the pigment | dye described in the item of Example 16-19 mentioned later -1700 B [refractive index: 1.50] was uniformly coated on the outermost surface of the laminated film using a bar coater. Subsequently, the accumulated irradiation intensity is 180 mJ / cm with a condensing high-pressure mercury lamp (I Graphics Co., Ltd. H04-L41) having an irradiation intensity of 120 W / cm ² set at a height of 13 cm from the surface of the hard coat layer. ^It was irradiated with ultraviolet light so as to be ² and cured to obtain a laminated sheet in which the hard coat layer was laminated on the laminated film. In addition, industrial UV checker (Nippon Battery Co., Ltd. product UVR-N1) was used for integrated irradiation intensity measurement of an ultraviolet-ray.

(8) Glass transition temperature, melting point A differential scanning calorimeter EXSTAR DSC6220 manufactured by Seiko Instruments Inc. was used. Measurement and reading of temperature were performed according to JIS-K-7122 (1987). After heating 10 mg of a thermoplastic resin sample on an aluminum pan from 25 ° C. to 300 ° C. at a rate of 10 ° C./min, rapidly cool it again, and increase the temperature from 25 ° C. to 300 ° C. at a rate of 10 ° C./min The glass transition temperature was taken as the temperature at the intersection point of the baseline when raising the temperature from room temperature and the tangent at the inflection point of the step transition portion, and the peak top of the endothermic peak was taken as the melting point.

(9) Accelerated weathering test "iPhone" (registered trademark) 6 which is a smartphone manufactured by Apple Inc. was used. The liquid crystal panel is removed, and the laminated film is bonded to the outermost surface of the polarizing plate located closest to the viewing side via the optical adhesive OCA, and then incorporated again into the housing of “iPhone” (registered trademark) 6 to promote It was a display for weathering test. The created display was installed on a Sunshine Weather Meter SS80 manufactured by Suga Test Instruments Co., Ltd. with the visible side as a light irradiation surface, and an accelerated weathering test for 500 hours was conducted. The device has a light intensity of 3 times the intensity similar to that of sunlight, and can simulate tests assuming long-term use outdoors. As the treatment conditions, the temperature in the tank was 60 ° C., the humidity in the tank was 50% RH, and the illuminance was 180 W / m ² .

(10) Evaluation of Contrast (Brightness) Measurement was performed using a brightness measuring device BM7 manufactured by Topcon Technohouse. Assuming that the luminance in the entire white display is A and the luminance in the entire black display is B, the contrast value is calculated according to the equation (4). According to the amount of contrast change before and after the accelerated weathering test, superiority and inferiority were evaluated as follows.

Contrast = B / A equation (4)
:: Contrast change after weathering test less than 3% ○: Contrast change before and after weathering test 3% to less than 5% Δ: Contrast change before and after weathering test 5% to less than 10% ×: Contrast change before and after weathering test 10% or more.

(11) Display hue evaluation The reflection colorimetric value in black display was measured using a spectrocolorimeter CM3600d manufactured by Konica Minolta Sensing, Inc. The change in the reflected hue before and after incorporating the laminated film of the present invention into a display was evaluated. Measurement conditions were a measurement diameter of 8 mm, a viewing angle of 10 °, and a light source D65, and the L value, a * value and b * value in the reflection SCI were read. According to the amount of change of the color value according to the equation (5), the superiority of the hue change was evaluated.

Amount of color change = {{(after L test-before L test) ² + (after a * test-before a test * ² + (b * after test-b * before test) ² } Formula (5)
A: hue change amount less than 2 〇: hue change amount 2 or more and less than 5 Δ: hue change amount 5 or more and less than 10 ×: hue change amount 10 or more

Example 1
As the thermoplastic resin A, polyethylene terephthalate (PET) having a refractive index of 1.58 and a melting point of 258 ° C. was used. Further, as the thermoplastic resin B, polyethylene terephthalate copolymerized with 20 mol% of cyclohexanedicarboxylic acid (CHDC) and 15 mol% of spiroglycol (SPG), which is a non-crystalline resin having a melting point of 1.55 having no melting point (PET / SPG 15 / CHDC 20) (δ _polym = 10.5) was used. The prepared crystalline polyester A and thermoplastic resin B were each introduced into two single-screw extruders, and the former was melted at 280 ° C. and the latter at 260 ° C. and kneaded. Then, after interposing 5 sheets of leaf disk filters of FSS type, respectively, while measuring with a gear pump, merge with 301 feed blocks having 301 slits, and alternately 301 layers in the thickness direction with a lamination ratio of 1.0 It was set as the laminated body laminated | stacked. Here, the slit length is designed to be stepped, and the intervals are all constant. The obtained laminate is configured such that the layer thickness is in the range of 60 nm to 80 nm, 151 layers of the thermoplastic resin A layer and 150 layers of the thermoplastic resin B layer are alternately arranged in the thickness direction. It was stacked. Also, the layer thickness distribution is a distribution in which the layer thickness monotonously increases in a stepwise manner toward the center from one end of the film in the thickness direction of the film, and then the layer thickness monotonously decreases in a stepwise manner toward the opposite end. It was The laminate is supplied to a T-die, formed into a sheet, and then quenched and solidified on a casting drum whose surface temperature is kept at 25 ° C. while applying an electrostatic application voltage of 8 kV with a wire, unstretched lamination I got a cast film.

  After heating the obtained laminated cast film with a group of rolls set at 100 ° C., the film is stretched 3.0 times in the longitudinal direction of the film while being rapidly heated from both sides of the film with a radiation heater between stretching lengths of 100 mm. Then it was cooled once. Subsequently, corona discharge treatment is applied to both sides of this laminated uniaxially stretched film in air, and the wet tension of the base film is 55 mN / m, and the treated side of the film has a slippery layer (with a meta bar of # 4 A water-based paint having a refractive index of 1.57 (containing a vinyl acetate-acrylic resin containing 3 wt% of colloidal silica with a particle size of 100 nm) was coated to form a transparent, easy-to-slip, and easy-to-adhere layer.

  The laminated uniaxially stretched film was introduced into a tenter, preheated with hot air of 90 ° C., and then stretched 5.0 times in the width direction of the film at a temperature of 140 ° C. The stretching speed in the width direction here was 4 m / min, and the temperature was constant. The stretched film was heat-treated with hot air at 210 ° C. in a tenter as it was, followed by 1% relaxation treatment in the width direction under the same temperature conditions, and then wound up to obtain a laminated film. The thickness of the laminated film was 20 μm, and by strongly stretching in the width direction, the orientation angle showed 3 °. As a result of evaluating the spectrum at the time of irradiating each linearly polarized light with respect to the direction parallel to the orientation angle and the direction perpendicular thereto, the numerical values shown in Table 1 are shown and it can be confirmed that it has reflection anisotropy The As the reflection spectrum, the reflection hue b * value indicates -6, the color of the reflection is not strongly recognized, and the film is relatively highly transparent.

  It bonded to the display for a weather test via the optical adhesive so that the transmission-axis direction of a polarizer and the width direction of laminated film might become parallel. When the brightness of the display before and after the weathering test was measured, the ultraviolet light was cut only by the reflection by the laminated structure, so the deterioration of the polarizer could not be completely suppressed, and the result showed a slight change in the brightness. However, it has a property that it can be mounted on a display and can be used outdoors even for a long time.

(Comparative example 1)
In Example 1, a feed block having a slit number of 41 was joined to form a laminate in which 41 layers were alternately laminated in the thickness direction with a lamination ratio of 1.0, and the film thickness was designed to be 10 μm. In the same manner as in Example 1, a laminated film was obtained. The thermoplastic resin A layer positioned on the outermost surface of the laminated film formed a surface thick film layer having a thickness of 3 μm. The reflection performance in the ultraviolet region and high energy visible light is not sufficient, and the drawability is not good, and the waveform of the reflection anisotropy is disturbed, which is not suitable as the concept of the laminated film in this development. The Even when mounted on a display, the deterioration of the luminance due to the deterioration of the contents became remarkable.

(Example 2)
Example 1 is carried out except that a feed block in which the number of slits is 51 is joined to form a laminate in which 51 layers are alternately stacked in the thickness direction with a lamination ratio of 1.0, and is a laminate having a thickness of 15 μm A laminated film was obtained in the same manner as Example 1. In order to improve film forming properties while reflecting ultraviolet light while the laminated film in Example 2 is formed, the thermoplastic resin A layer located on the outermost surface of the laminated film formed a surface thick film layer having a thickness of 5 μm. The performance of the laminated film of Example 2 is as shown in Table 1, and although it is slightly inferior to the Example 1 in the reflection performance, it has properties usable as a display.

(Example 3)
Example 1 is carried out except that it is made into a laminated body in which 101 layers of feed blocks having 101 slits are merged to alternately form 101 layers in the thickness direction with a lamination ratio of 1.0 and a thickness of 16 μm is used. A laminated film was obtained in the same manner as Example 1. The thermoplastic resin A layer positioned on the outermost surface of the laminated film formed a surface thick film layer having a thickness of 5 μm. The performance of the laminated film of Example 3 is as shown in Table 1, and the ultraviolet ray was reflected in a wider band and higher reflection than Example 2 and had the ability to be used as a display member.

(Example 4)
Example 1 is carried out except that it is made into a laminated body in which 201 layers of feed blocks having 201 slits are alternately joined in the thickness direction with a lamination ratio of 1.0 and a laminated body with a thickness of 15 μm is obtained. A laminated film was obtained in the same manner as Example 1. The thermoplastic resin A layer positioned on the outermost surface of the laminated film formed a surface thick film layer having a thickness of 1 μm. The performance of the laminated film of Example 4 is as shown in Table 1. The ultraviolet ray was reflected with high reflectivity over the entire ultraviolet ray area, and had the ability to be used as a display member for a long time.

(Example 5)
Example 1 is carried out except that a feed block having a slit number of 501 is joined to form a laminate in which 501 layers are alternately laminated in the thickness direction of a lamination ratio of 1.0 and a laminate having a thickness of 35 μm is obtained. A laminated film was obtained in the same manner as Example 1. By increasing the number of slits, the reflectance in the ultraviolet region is improved, and the property of being excellent in the ultraviolet ray cut-off property as compared with Example 1 is exhibited, and it has a property which can be sufficiently mounted on a display.

(Example 6)
A laminated film was obtained in the same manner as in Example 1 except that the total thickness of the film was 16 μm and the reflection wavelength band was shifted to the long wavelength side in Example 1. Even when the reflection wavelength was shifted to the long wavelength side, the reflection anisotropy was maintained, and the transmittance tended to decrease as a whole. On the other hand, the tint of the laminated film showed a tendency to intensify the blue hue due to reflection. However, the cuttability at the time of mounting in a display is good, and it has the property which can be mounted as a display member.

(Example 7)
In Example 1, after heating the laminated cast film with a group of rolls set at 100 ° C., it is stretched 3.6 times in the longitudinal direction, cooled, and subjected to a coating process to obtain 3.3 in the width direction at a temperature of 140 ° C. It was stretched twice. Then, after heating with a roll group set to 100 ° C. as in the former, a laminated film was obtained by performing a second stretching 1.2 times in the longitudinal direction. The draw ratio in the longitudinal direction was 4.3 times, and the orientation angle was 1 °. The reflection anisotropy showed a rather weak tendency as compared with Example 1 because the difference in draw ratio in the longitudinal direction and in the width direction was small. After the bonded display was prepared so that the transmission axis direction of the polarizer and the longitudinal direction of the laminated film were parallel to each other, an accelerated weathering test was carried out. It had a property that could withstand

(Example 8)
A laminated film was obtained in the same manner as in Example 1 except that the film was stretched 6.0 times in the width direction at a temperature of 140 ° C. in Example 1. By stretching more strongly in the width direction, the reflection anisotropy in the orientation direction and in the direction perpendicular to it tends to be intensified. As the reflection anisotropy is enhanced, the entire reflection spectrum is formed over a wider wavelength band, and the hue change after mounting of the display is slightly increased as compared with Example 1.

(Example 9)
A laminated film was obtained in the same manner as in Example 8 except that the film was stretched 7.0 times in the width direction at a temperature of 140 ° C. in Example 8. Although the reflection anisotropy was enhanced by stretching very strongly in the width direction, tearing in the width direction of the laminated film was clearly confirmed at the tenter outlet. The scrap samples were evaluated and had sufficient properties for mounting on a display.

(Comparative example 2)
In Example 1, after heating the laminated cast film with a group of rolls set at 100 ° C., it is stretched 3.3 times in the longitudinal direction, cooled, and subjected to a coating process to obtain 3.3 in the width direction at a temperature of 140 ° C. A laminated film was obtained in the same manner as in Example 1 except that the film was double-drawn and the draw ratio was made to coincide in the longitudinal direction and in the width direction. Although the laminated film itself did not exhibit reflection anisotropy, the orientation angle showed 39 °, but it showed a constant spectral transmission spectrum even when irradiated with linearly polarized light oscillating in any direction. Although the sharp cuttability is shown, the cuttability of the high energy visible light region is insufficient, and the result that the luminance change when mounted on the display is large is shown.

(Comparative example 3)
A laminated film was obtained in the same manner as in Comparative Example 2 except that the thickness of the laminated film was increased from 20 μm to 21 μm and the spectral transmission spectrum was shifted to the long wavelength side in Comparative Example 2. Also in this case, although the orientation angle showed 42 °, the spectral transmission spectrum showed a constant waveform even when irradiated with linearly polarized light oscillating in any direction. Although sharp-cut properties and long-wavelength ultraviolet-cut properties are exhibited, the blue hue due to reflection after mounting on a display is very strong, which is not preferable as a display member.

(Comparative example 4)
Example 1 was carried out in the same manner as Example 1, except that the film was stretched 3.3 times in the longitudinal direction with the rolls set at 100 ° C., and further stretched 3.6 times in the width direction at a temperature of 140 ° C. A laminated film was obtained. The reflection spectrum is small due to the small difference between the stretch ratio in the longitudinal direction and the width direction, and in the case of irradiation with linearly polarized light in the alignment direction and in the case of irradiation with linearly polarized light in the direction orthogonal to the alignment direction There was no difference. Since the cuttability in the ultraviolet region and the high energy visible light region is insufficient, the deterioration of the contents can not be suppressed, and the result that the change in luminance when mounted on the display is large is shown.

(Example 10)
A laminated film was obtained in the same manner as in Example 1 except that the heat treatment was carried out with hot air at 220 ° C. in a tenter in Example 1. Although the orientation angle at the widthwise position was slightly deteriorated by raising the heat treatment temperature, the rainbow unevenness was not visually recognized strongly even when mounted on a display, and had properties sufficient for use.

(Example 11)
In Example 1, a thermoplastic resin B was prepared from a benzotriazole-based ultraviolet absorber (2,2′-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6-) having a molecular weight of 650 g / mol. (2H-benzotriazol-2-yl) phenol) (δ _UVA = 12.2) was added so as to be 2 wt% with respect to the resin composition constituting B layer containing thermoplastic resin B as a main component A laminated film was obtained in the same manner as in Example 1 except for the addition of the ultraviolet light absorber, the cutability in the ultraviolet region became sufficient, while the laminated film was slightly whitened after the accelerated weathering test. The tendency is shown, and the result of the luminance change is not different from that of Example 1.

(Example 12)
In Example 1, in the thermoplastic resin B, a triazine-based ultraviolet absorber (2,4,6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -s-triazine having a molecular weight of 700 g / mol is used. Example 6 was carried out in the same manner as Example 1, except that (δ _UVA = 11.6) was added in an amount of 1.5 wt% with respect to the resin composition constituting B layer containing thermoplastic resin B as the main component. Thus, a laminated film was obtained. The triazine-based UV absorber highly efficiently absorbs ultraviolet light over a wide range, and exhibits a property of being non-crystalline and difficult to bleed out because of the long alkyl difference. The later luminance change was more suppressed, and showed the property suitable for the member of the display used over a long period of time.

(Comparative example 5)
In Example 1, polyethylene terephthalate (PET) having a melting point of 258 ° C. is used as the thermoplastic resin A and the thermoplastic resin B, and the same UV absorber as that used in Example 12 is added to the thermoplastic resin B. Into a single single-screw extruder except that the layers A and B containing the thermoplastic resins A and B as main components are added to the resin composition so as to be 0.75 wt%. A laminated film was obtained in the same manner as in Example 1 except that a membrane film was formed. Due to the single film construction, no reflection zone was generated, and the film exhibited properties as a normal ultraviolet absorbent-containing single film film. Although the reflection hue is not shown and highly transparent, the wavelength of the ultraviolet light region and the high energy visible light region can not be cut sufficiently, so that it has a property which can not be used as a member for a display used for a long time.

(Example 13)
A laminated film was obtained in the same manner as in Example 12 except that the thickness of the laminated film was 19.5 μm and the reflection wavelength band was short-wavelength shifted in Example 12. As compared with Example 12, the reflected hue can be suppressed by shifting the wavelength to a short wavelength, and the spectrum showing the long wavelength side at the time of polarized light irradiation has a property of sufficiently cutting the long wavelength ultraviolet region as in Example 12 It had desirable properties as a display member to be used for a long time.

(Example 14)
In Example 1, in the thermoplastic resin B, a benzotriazole-based ultraviolet absorber (2- (5-dodecylthio-2H-benzotriazol-2-yl) -6-tert-butyl-4- (4- (4-dodecylthio-2H) -benzotriazol-2-yl)) having a molecular weight of 454 g / mol. Similar to Example 1 except that methylphenol (δ _UVA = 11.2) was added to be 2 wt% with respect to the resin composition constituting B layer containing thermoplastic resin B as a main component. Thus, a laminated film was obtained. By the addition of the ultraviolet absorber having a sulfur atom, the absorption band was slightly shifted to the long wavelength side, and the maximum absorption wavelength showed 369 nm, thereby exhibiting the property of cutting even a light beam in the high energy visible light region. As a result, the intensity of the reflected hue was reduced, and a more highly transparent laminated film could be obtained.

(Example 15)
A laminated film was obtained in the same manner as in Example 12 except that the stretching speed in the width direction was changed to 0.8 m / min. As the drawing speed was reduced, the state of orientation was different at the widthwise position, the orientation angle was 10 ° at the widthwise position, and 1 ° at the central position. The performance is as described in the table, and showed a property which can withstand long-term use as a display member.

(Example 16)
A laminated film was obtained in the same manner as in Example 12 except that the stretching speed in the width direction was 10 m / min in Example 12. By increasing the drawing speed, the uniformity at the position in the width direction became more excellent, but film breakage was occasionally confirmed. An orientation angle of 0 ° at the center position and 2 ° at the widthwise position is shown. As described in the table, it showed excellent reflection anisotropy.

(Example 17)
A laminated film was obtained in the same manner as in Example 12 except that the stretching speed in the width direction was changed to 15 m / min in Example 12. Although the film breakage occurred frequently, when the broken laminated film was evaluated, it showed an orientation angle of 0 ° at both the center position and the width direction position, and showed excellent uniformity in the width direction.

(Example 18)
A laminated film was obtained in the same manner as in Example 12 except that the stretching speed in the width direction was changed to 0.5 m / min in Example 12. The orientation angle at the widthwise position showed a high value of 16 °, but the direction of the orientation at each position and the reflection anisotropy in the direction orthogonal thereto exhibited the same properties as in Example 11.

(Example 19)
Evaluation was performed by laminating the laminated film obtained in Example 12 so that the orientation axis direction was perpendicular to the transmission axis direction of the polarizer. As the axis became vertical, the cuttability of the transmitted light from the backlight showed the short wavelength cuttability described in the table. As a result, the ultraviolet ray cuttability tends to decrease as compared with Example 12, and in the accelerated weathering test, the amount of luminance change equivalent to that of Example 1 is shown, but the property which can withstand long-term use as a display member Indicated.

Example 20
A hard coat layer is provided on one side of the laminated film obtained in Example 12, and a naphthalimide dye having a maximum absorption wavelength of 382 nm is contained in the hard coat layer, and 1 wt% relative to the resin composition constituting the hard coat layer. A laminated film was obtained in the same manner as in Example 12 except that the additive was added to give By adding the naphthalimide dye having a maximum absorption wavelength of 382 nm, the reflected light of the laminated film can be absorbed, so that the reflected hue can be reduced as compared with Example 12, and a higher transparent laminated film can be obtained. . Although the naphthalimide dye tended to lose some cuttability after the weathering test, the properties sufficient for long-term use were shown, and the other properties were similar to those obtained in Example 12.

(Example 21)
In Example 20, the pigment in the hard coat layer is an azo-based yellow pigment having a maximum absorption wavelength of 478 nm, and the content of the pigment is 0.3 wt% with respect to the resin composition constituting the hard coat layer. A laminated film was obtained in the same manner as in Example 20 except that the additive was added. It is a pigment addition for hue adjustment, and by neutralizing the blue hue of the reflected light with a yellow pigment, the reflected hue can be brought close to neutral, and a highly transparent laminated film is obtained. Other properties were similar to those obtained in Example 20.

(Example 22)
In Example 12, a hard coat layer is provided on one side of the laminated film, and an acrylic optical pressure sensitive adhesive having 0.3 wt% of naphthalimide dye having a maximum absorption wavelength of 382 nm added to the side opposite to the hard coat layer It applied so that it might be set to 20 micrometers in thickness by bar coat. After applying the adhesive, it was dried in an oven at 100 ° C. for 2 to 3 minutes, and then subjected to an aging treatment in a hot air oven at 40 ° C. for 2 days to obtain a laminate. The optical performance of this laminate was equivalent to that of Example 20. When laminated to a display so that the hard coat layer is disposed on the foremost side on the viewing side, as shown in Example 20, the laminated film has the property of sufficiently cutting light in the ultraviolet region. The dye did not show any deterioration of pigment and showed sharp long-wavelength ultraviolet cuttability over a long period of time.

(Example 23)
In Example 20, the addition amount of the naphthalimide dye added to the hard coat layer is reduced to 0.5 wt%, and further, a naphthalimide dye having a maximum absorption wavelength of 382 nm on the face opposite to the face provided with the hard coat layer. A laminate was obtained in the same manner as in Example 20 except that an acrylic optical pressure-sensitive adhesive to which 0.3 wt% of W was added was applied to a thickness of 20 μm by bar coating. The adhesive treatment step was carried out in the same manner as in Example 22. In the laminate, the reflected hue can also be suppressed, and the effect of the dye added to the pressure-sensitive adhesive exhibited sharp long-wavelength ultraviolet cuttability over a long period of time.

  Hereinafter, the evaluation result etc. of the film of each Example and a comparative example are shown to Tables 1-4.

  When the laminated film of the present invention is disposed at the front surface position of the polarizing plate of the display so that the polarization axis direction of the polarizer and the orientation angle become substantially parallel, the linearly polarized light obtained by transmitting through the polarizer is irradiated. In addition, because it can exhibit a unique long-wavelength ultraviolet cuttability and does not exhibit such long-wavelength ultraviolet cuttability to natural light from the outside, it is highly transparent but has higher efficiency than conventional laminated films. It is possible to prevent the deterioration of the display contents over a long period of time. The display can be widely used in applications using a polarizing plate, and in particular, it can exert strong effects in the field of digital signage and in-vehicle displays, which are displays used outdoors.

1: Maximum value of reflectance 2: Half value of maximum value of reflectance 3: Cutoff wavelength 4: Reflection cut end 5 on the short wavelength side 5: Reflection cut end on the long wavelength side 6: Reflection band 7: Irradiated with natural light Spectral transmission spectrum 8 of the X-wave or Y-wave when irradiated with polarized light showing short-wavelength cuttability 9: when irradiated with polarized light showing long-wavelength cuttability of X-wave or Y-wave Spectral transmission spectrum 10: interior panel portion 11: display portion 12: reflecting mirror 13: projection member 14: virtual image 15 to be recognized visually: light path 16: light projection device

Claims (15)

A laminated film in which 51 layers or more of a layer A mainly composed of a thermoplastic resin A and a layer B mainly composed of a thermoplastic resin B having a refractive index different from that of the thermoplastic resin A are alternately laminated,
Absolute light transmittance determined by irradiating linearly polarized light (X wave) vibrating in the film orientation direction, and absolute light beam determined by irradiating linearly polarized light (Y wave) vibrating in the direction perpendicular to the orientation direction Among the transmittances, one absolute light transmittance is 10% or more at a wavelength of 400 nm, 70% or more at a wavelength of 420 nm, and 80% or more at a wavelength of 440 nm, and the other absolute light transmittance is 10% at a wavelength of 400 nm The laminated film which is less than 70% at a wavelength of 420 nm and 80% or more at a wavelength of 440 nm. The laminated film according to claim 1, wherein a maximum value of relative light transmittance at a wavelength of 300 nm or more and less than 380 nm is 10% or less. The cutoff wavelength Λ at a wavelength of 400 nm or more is 400 nm or more and 440 nm or less, the absolute value of the reflected hue b * value is 10 or less, and the cutoff wavelength Λ and the reflected hue b * value at a wavelength of 400 nm or more are The laminated film according to claim 1, which satisfies the relational expression.
b *> − 0.805Λ + 320 formula (2) The laminated film in any one of Claims 1-3 containing a ultraviolet absorber. The solubility parameter of the UV absorber is δ _UVA [(cal / cm ³ ) ^1/2 ], and the solubility parameter of the thermoplastic resin containing the UV absorber is δ _polym [(cal / cm ³ ) ^1/2 ] The laminated film according to claim 4, wherein | δ _UVA −δ _polym | ≦ 2.0. The laminated film according to claim 4 or 5, wherein the UV absorber is a benzotriazole-based and / or triazine-based UV absorber containing a sulfur atom. The laminated film according to any one of claims 1 to 6, which is used for display applications. The laminated film in any one of Claims 1-7 used for the display use which has a polarizer. When used as a display application having a polarizer, of the X and Y waves, the optical axis of linearly polarized light showing less than 10% at a wavelength of 400 nm, less than 70% at a wavelength of 420 nm, and 80% or more at a wavelength of 440 nm The laminated film according to claim 8, wherein the laminated film is used in parallel with the transmission axis of the inner polarizer. The laminated film according to claim 8 or 9, which is used as a display application having a polarizer, disposed on the viewing side inside the display rather than the polarizer. The laminated film according to any one of claims 8 to 10, which is used for a head-up display application having a polarizer. The lamination sheet which provides the hard-coat layer (C layer) which has curable resin C as a main component on at least single side | surface of the laminated film in any one of Claims 1-11. The hard coat layer (C layer) containing the curable resin C as a main component contains an ultraviolet light absorber and / or a dye having a maximum wavelength which is maximum at a wavelength of 380 nm or more and 410 nm or less or a wavelength of 470 nm or more and 500 nm or less The laminated sheet according to claim 12. A laminate comprising the laminated film according to any one of claims 1 to 11 or the laminated sheet according to claim 12 provided with an adhesive layer containing an ultraviolet light absorber and / or a dye. A display comprising the laminated film according to any one of claims 1 to 11.

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